Gas Chromatography Essential Hardware

and Operations

Tracy J Benson

Dan F Smith Department of Chemical Engineering

Lamar University

December 3 2009

Definitions

  13 Chromatography13 a13 general13 term13 applied13 to13 a13 wide13 variety13 of13 separa6on13 techniques13 based13 upon13 the13 sample13 par66oning13 between13 a13 moving13 phase13 which13 can13 be13 gas13 or13 liquid13 and13 a13 sta6onary13 phase13 which13 may13 be13 either13 a13 liquid13 or13 solidrdquondash13 [Johnson13 and13 Stevenson13 1978]13

 Phases 13 13

Technique13 13 13 Phase13 113 13 13 13 Phase13 213 13 chromatography 13 sta6onary13 13 13 13 mobile13 13

13 extrac6on13 13 13 raffinateextractant13 Dialysis 13 13 retentatediffusate13

Definitions

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte a substance that is the subject of chemical analysis Analyte a substance that is the subject of chemical analysis 10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Chromatography is an equilibrium-driven process

AmobilehArrAstationary

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Equilibrium constant (K) partition coefficient expressed as the Equilibrium constant (K) partition coefficient expressed as the molar concentration of the analytein the stationary phase divided by the molar concentration of the analytein the mobile phase

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte retention time (tR) the elapsed time between analyte injection and analytepeak reaching a detector at the end of the column

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Mobile phase retention time (tM) the time necessary for the Mobile phase retention time (tM) the time necessary for the mobile phase to pass through the column

Introduction

bull GC is most widely used analytical technique in the world ndash Over 50 years in development ndash Over 25000 in use in US ndash Worldwide market gt $1billion bull GC is premier technique for separation and analysis of volatile compounds ndash Gases liquids dissolved solids ndash Organic and inorganic materials ndash MW from 2 to gt 1000

bull Fast analysis ndash Typically minutes (even sec) ndash Can be automated bull Small samples (microlof injection microganalyte needed) bull High resolution ndash Record N ~ 13 x 106

bull Reliable relatively simple and cheap bull Non-destructive ndash Allows on-line coupling eg to MS bull Sensitive detectors (easy ppm often ppb) bull Highly accurate quantification (1-5 Relative Std Dev)

Advantages of GC

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Definitions

  13 Chromatography13 a13 general13 term13 applied13 to13 a13 wide13 variety13 of13 separa6on13 techniques13 based13 upon13 the13 sample13 par66oning13 between13 a13 moving13 phase13 which13 can13 be13 gas13 or13 liquid13 and13 a13 sta6onary13 phase13 which13 may13 be13 either13 a13 liquid13 or13 solidrdquondash13 [Johnson13 and13 Stevenson13 1978]13

 Phases 13 13

Technique13 13 13 Phase13 113 13 13 13 Phase13 213 13 chromatography 13 sta6onary13 13 13 13 mobile13 13

13 extrac6on13 13 13 raffinateextractant13 Dialysis 13 13 retentatediffusate13

Definitions

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte a substance that is the subject of chemical analysis Analyte a substance that is the subject of chemical analysis 10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Chromatography is an equilibrium-driven process

AmobilehArrAstationary

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Equilibrium constant (K) partition coefficient expressed as the Equilibrium constant (K) partition coefficient expressed as the molar concentration of the analytein the stationary phase divided by the molar concentration of the analytein the mobile phase

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte retention time (tR) the elapsed time between analyte injection and analytepeak reaching a detector at the end of the column

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Mobile phase retention time (tM) the time necessary for the Mobile phase retention time (tM) the time necessary for the mobile phase to pass through the column

Introduction

bull GC is most widely used analytical technique in the world ndash Over 50 years in development ndash Over 25000 in use in US ndash Worldwide market gt $1billion bull GC is premier technique for separation and analysis of volatile compounds ndash Gases liquids dissolved solids ndash Organic and inorganic materials ndash MW from 2 to gt 1000

bull Fast analysis ndash Typically minutes (even sec) ndash Can be automated bull Small samples (microlof injection microganalyte needed) bull High resolution ndash Record N ~ 13 x 106

bull Reliable relatively simple and cheap bull Non-destructive ndash Allows on-line coupling eg to MS bull Sensitive detectors (easy ppm often ppb) bull Highly accurate quantification (1-5 Relative Std Dev)

Advantages of GC

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Definitions

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte a substance that is the subject of chemical analysis Analyte a substance that is the subject of chemical analysis 10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Chromatography is an equilibrium-driven process

AmobilehArrAstationary

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Equilibrium constant (K) partition coefficient expressed as the Equilibrium constant (K) partition coefficient expressed as the molar concentration of the analytein the stationary phase divided by the molar concentration of the analytein the mobile phase

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703Analyte retention time (tR) the elapsed time between analyte injection and analytepeak reaching a detector at the end of the column

10485761048577104857810485791048580104858110485821048583104858410485851048586104858710485881048589104859010485911048592104859310485941048595104859610485971048598104859910486001048601104860210486031048604104860510486061048607104860810486091048610104861110486121048613104861410486151048616104861710486181048619104862010486211048622104862310486241048625104862610486271048628104862910486301048631104863210486331048634104863510486361048637104863810486391048640104864110486421048643104864410486451048646104864710486481048649104865010486511048652104865310486541048655104865610486571048658104865910486601048661104866210486631048664104866510486661048667104866810486691048670104867110486721048673104867410486751048676104867710486781048679104868010486811048682104868310486841048685104868610486871048688104868910486901048691104869210486931048694104869510486961048697104869810486991048700104870110487021048703 Mobile phase retention time (tM) the time necessary for the Mobile phase retention time (tM) the time necessary for the mobile phase to pass through the column

Introduction

bull GC is most widely used analytical technique in the world ndash Over 50 years in development ndash Over 25000 in use in US ndash Worldwide market gt $1billion bull GC is premier technique for separation and analysis of volatile compounds ndash Gases liquids dissolved solids ndash Organic and inorganic materials ndash MW from 2 to gt 1000

bull Fast analysis ndash Typically minutes (even sec) ndash Can be automated bull Small samples (microlof injection microganalyte needed) bull High resolution ndash Record N ~ 13 x 106

bull Reliable relatively simple and cheap bull Non-destructive ndash Allows on-line coupling eg to MS bull Sensitive detectors (easy ppm often ppb) bull Highly accurate quantification (1-5 Relative Std Dev)

Advantages of GC

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Introduction

bull GC is most widely used analytical technique in the world ndash Over 50 years in development ndash Over 25000 in use in US ndash Worldwide market gt $1billion bull GC is premier technique for separation and analysis of volatile compounds ndash Gases liquids dissolved solids ndash Organic and inorganic materials ndash MW from 2 to gt 1000

bull Fast analysis ndash Typically minutes (even sec) ndash Can be automated bull Small samples (microlof injection microganalyte needed) bull High resolution ndash Record N ~ 13 x 106

bull Reliable relatively simple and cheap bull Non-destructive ndash Allows on-line coupling eg to MS bull Sensitive detectors (easy ppm often ppb) bull Highly accurate quantification (1-5 Relative Std Dev)

Advantages of GC

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

bull Fast analysis ndash Typically minutes (even sec) ndash Can be automated bull Small samples (microlof injection microganalyte needed) bull High resolution ndash Record N ~ 13 x 106

bull Reliable relatively simple and cheap bull Non-destructive ndash Allows on-line coupling eg to MS bull Sensitive detectors (easy ppm often ppb) bull Highly accurate quantification (1-5 Relative Std Dev)

Advantages of GC

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

bull Limited to volatile samples ndash T of column limited to ~ 380 degC ndash Need Pvap of analyte ~ 60 torr at that T ndash Analytes should have bp below 500 degC bull Not suitable for thermally labile samples bull Some samples may require intensive preparation ndash Samples must be soluble and not react with the column bull Requires spectroscopy (usually MS) to confirm the peak identity

Disadvantages of GC

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Instrument Overview GC-MS Configuration

Other Analyzers Flame ionization Thermal conductivity Electron-capture Atomic Emission Flame photometric and more

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

bull Carrier gas Mobile phase (H2 He N2) ndash Flows continuously throughout instrument ndash Carries the sample vapor through the column to detector bull Necessary properties ndash INERT bull Does not chemically interact with sample ndash COMPATIBLE with detector bull No noise or explosions ndash HIGHLY PURIFIED bull Impurities will degrade column and cause noise in detector bull ldquoResearch graderdquo is expensive but is necessary

Carrier Gas Properties

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Flow Rate of Carrier Gas

bull Flow rates must be precisely controlled ndash Reproducible retention times minimize detector drift bull Flow rates of carrier gas ndash Linear flow rate (cms) u = Ltr ndash Volumetric flow rate (mLmin) u (π r2) L is length of column tr is retention time r is the internal radius of column bull Flow rate depends on type of column ndash Packed column 25-100 mLmin ndash Capillary column microLmin to 1 mLmin bull Flow rate will decrease as column T increases ndash Viscosity of carrier gas increases with T

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

bull Properties ndash Versatile rapid quantitative ndash Introduce sample to column as a sharp symmetric band bull Heated injection port ndash Vaporize sample (50 degC gtanalyte bp) ndash Low enough to avoid degradation bull Packed columns ndash Flash vaporizer or on-column bull Capillary columns ndash Split 1-2 Higher resolution ndash Splitless ~100 Trace analysis

Injection Process 13

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

SplitSplitless Injector

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

On ndash Column Injector

 Cool injector to below boiling point of solvent  Quickly raise injector temperature after injection of sample  Offers less discrimination for ldquoheavyrdquo molecules (ie acylglycerides)

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Types of GC Columns

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Packed GC Columns

bull Easy to make and use bull Limited resolution (N lt 8000) bull Outside Solid tubing usually made of stainless steel ndash Because of strength ndash Glass when more inert substrate is needed bull Inside Tightly packed with inert support ndash Solid supports should be inert and have high surface area ndash Typically diatomaceous earth or fluorocarbon polymer bull Stationary liquid phase is coated on the solid support ndash 3-10 by weight of the solid support

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Open (Capillary) Columns

bull Most common and efficient bull High resolution (N gt 100000) bull Outside Solid tubing made from fused silica ndash Inert flexible strong and easy to use bull Inside Column is an open tube ndash Very low resistance to flow ndash Long lengths possible ( L gt 100 m) bull Stationary phase is a thin uniform liquid film coated on the wall of the tubing

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

bull Packed Column ndash Lower resolution ndash Fewer peaks (16) ndash Fewer plates

bull Capillary Column ndash Small sample needed ndash Better resolution ndash More peaks ndash Faster Analysis

Column Type vs Separation

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Column Efficiency   13 Rate13 Theory13 of13 Chromatography13

 More13 realis6c13 descrip6on13 of13 how13 peak13 broadening13 occurs13  Van13 Deemter13 Equa6on13 13

13 13 HETP13 =13 A+Bμ13 +13 Cμ13

where13 A13 is13 the13 eddy13 diffusion13 term13 B13 is13 the13 longitudinal13 diffusion13 term13 C13 is13 the13 resistance13 to13 mass13 transfer13 coefficient13 and13 μ13 is13 the13 linear13 velocity13

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Stationary Phases for GC

bull Hundreds of SP have been used ndash Only requirements are bull Low vapor pressure bull Thermal stability bull Low viscosity (for fast mass transfer) bull High selectivity for compounds of interest

bull How do you decide ndash Literature searches ndash Ask around talk to manufacturers ndash Trial and error

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Typical Stationary Phases

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Derivatization

bull If changing the column wonrsquot help you may change the separation by changing the analyte ndash Cause a non-volatile sample to become volatile ndash Improves selectabilityof derivative bull Example silynation ndash Introduce trimethylsilyl group to make sample volatile

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Common GC Detectors

  Flame Ionization Detector (FID)  Thermal Conductivity Detector (TCD)   Electron Capture Detector (ECD)   Flame Photometric Detector (FPD)   Mass Spectrometer (MS)

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

Comparison of Various Common GC Detectors

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

FIDDetects analytes by measuring an electrical current generated by electrons from burning carbon particles in the sample

Great for organic compounds

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

TCD Detects changes in thermal conductivity such as when organic molecules displace some of the carrier gas cause a temperature rise in the element which is sensed as a change in resistance The TCD is not as sensitive as other detectors but it is non-specific and non-destructive

Particularly suited for fixed gas analysis (ie CO CO2 O2 H2 etc)

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

ECDuses a radioactive Beta emitter (electrons) to ionize some of the carrier gas and produce a current between a biased pair of electrodes When organic molecules that contain electronegative functional groups such as halogens phosphorous and nitro groups pass by the detector they capture some of the electrons and reduce the current measured between the electrodes The ECD is as sensitive as the FID but has a limited dynamic range and finds its greatest application in analysis of halogenated compounds

Particularly suited for halides nitrates nitriles peroxides anhydrides and organometallics13

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

MSThe only method of detection that can offer true identification of the analyte Productions of ions stems from bombardment by electrons to produce a fragmentation of ions from the parent compound The pattern of fragmentation is governed by gas-phase reactions and are rather unique for any type of compound

Acetone13 CH3COCH313 Ephedrine13

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis

References

bull Braithwaite and Smith ndash Chromatographic Methods bull Grant ndash Capillary Gas Chromatography bull McNair and Miller ndash Basic Gas Chromatography bull Rubinson ndash Contemporary Instrumental Analysis bull Skoog Holler and Nieman ndash Principles of Instrumental Analysis