introduction of gc-ms

GC-MS The world leader in serving science

Single Quadruple and Ion Trap

2

Vacuum SystemIonization Method Mass Analyzer Detector Data System

GC

Atmosphere

3

Mass Spectrometry

4

What is Mass SpectrometryThe basis of MS (mass spectrometry) is the production of ions that are subsequently separated or filtered according to their mass-to-charge (m/z) ratio and detected. The resulting mass spectrum is a plot of the (relative) abundance of the produced ions as a function of the m/z ratio.

5

254.2 100 507.3

% 334.3 194.2 399.7 0 100 200 300 400 500 600 m/z

6

4S Sensitivity () Speed () Specificity () Stoichiometry ()7

HEWLET PACKAR T D 5972A Mass Selective Detecto r

1.0 DEG/MI N

HEWLETT PACKARD

Sample

Gas ChromatographB

Mass Spectrometer (MS)A BC

D C B ASample

A

C

D

D

Separation8

Identification

GC-MS v.s GCGC-MS GC-MS GC-MS (S/N) GCMS

9

The world leader in serving science

Ionization Methods

Electron Impact

Ionization Methods CI (NICI; PICI) Ionization EI

Soft

Hard Fragments

No FragmentsSoft ionization gives low fragmentation Molecular weight determination Produces theoretical spectra High sensitivity (low pg levels)11

EI Spectra from TRACE DSQ

HCB spectra from 2 pg up to 60 ngScan EI+ 100 % 0 100 % 0 100 % 0 50 71 71 71 2 pg HCB 107 142 177 214 249 284 282 288 253 Scan EI+ 200 pg HCB 107 142 179 214 249 284 282 288 253 Scan EI+ 60 ng HCB 107 100 142 150 177 214 200 249 250 284 282 288 253 300 m/z 350

12

CIP Spectra Comparison of EI with PCI using methane and ammoniaScan EI+ 100 % 51 0 100 % 0 100 % 0 50 100 150 183 105 105 77 76 78 106 182 152 181 183 Scan CI+ 183 184 211 223 benzophenone methane CI+ Scan CI+ 200 201 200 benzophenone ammonia CI+ 217 250 300 m/z 350 benzophenone, EI

13

Electron IonizationGCMS

Most common method of ionization for GC-MS Used as both a qualitative and quanitative tool Produces mass spectra of molecules Fragmentation fingerprints Combine with retention time for positive identification

Use single ion for quantitation with one or more ions for verification

14


Ionization Methods

Chemical Ionization


Ionization Methods Positive Ion Chemical Ionization

Reagent gas reacts with electrons to form reactive species

Result is softer ionization which results in primary formation of molecular ions.

Main use is molecular weight confirmation17

PICI SummaryMolecular weight information

Increased selectivity for many compounds

Selectivity affected by reagent gas

CI High pressure CI produces true CI spectra (including adduct ions for confirmation)18


Ionization Methods Negative Ion Chemical Ionization

NICI Reagent gas reacts with electrons to form plasma of thermal electrons

Ionization is favored by molecules which have a high electron affinity electron capture

Useful for selective analysis in heavy matricies, ie.e pesticide in food or waste matrix.20

NICI Summary Molecular weight information Highly sensitive and selective - ideal for analytes in complex matrices

21

DetectorElectron Multiplier (Most common) Faraday Cup Photomultiplier Conversion Dynode Array Detector Charge (or Inductive) Detector22


MS Detection

Answers the two most frequently asked questions in Analytical chemistry IDENTITY - What is in this sample?

QUANTITY - How much of it is in this sample?

24

How does an MS detector do this?

MS detectors constantly acquire Mass Spectra 1-5 spectra are acquired per second i.e. mass range 50-550 amu, scan rate 5 scan/sec, ~ 2500 amu/s A chromatographic run is defined by thousands of mass spectra

25

Chromatograms?

100

TIC TIC

If we zoom into this region... region...%

50 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25

Time Time

26

Chromatograms close-up

100

TIC

%

At this scale the trace is made from many data points

78 2.12 2.14 2.16 2.18 2.20 2.22 2.24 2.26 2.28

Time

27

Mass Spectrumproduced by scanning the MS between 50 and 300 amu whilst compound elutes into the system

100

240

%

2410 60 80 100 120 140 160 180 200 220 240 260 280 300

28

What is a Mass Spectrum?

A mass spectrum is a chemical fingerprint It contains: Molecular weight information Structural information

29

Each position on the chromatogram has a unique mass spectrum

30

Trace produced by summing all observed masses in each scan

Total Ion Chromatogram or TIC

31

Data View - ChromatogramWe can also just show the data for a specific mass This lets us see only the information from a single compound

32

Mass chromatogram

100 100

240.27 240.27 1.41e5 1.41e5

% %

Mass 240TIC TIC 4.67e5 4.67e5

0 0 100 100

% %

TIC0 0 1.40 1.40 1.60 1.60 1.80 1.80 2.00 2.00 2.20 2.20 2.40 2.40 2.60 2.60 2.80 2.80 3.00 3.00 Time Time

33

Data View - Extracted ion trace

Removes the effect of background Increases signal to noise Separates co-eluting peaks

34

Data View - Extracted ion trace2 closely eluting peaks as seen on the TIC. But each peak represents a different compound with a different mass spectral fingerprint.

100

TIC 1.57e5

%

0 11.00 12.00

Time

35

Data View - Extracted ion trace254.2 100 507.3 100 % 194.2 0 100 100 200 300 194.2 400 500 600 % 334.3 399.7 m/z TIC 1.57e5

%

226.2 0 100 200 300

402.2 460.2 400 500

580.4 600 m/z 0 11.00 12.00 Time

36

Separating co-eluting peaks

100 % 0 100 % 0 100 % 0 10.50 11.00 11.50 12.00 12.50

254.23 5.81e4

194.20 6.14e4

TIC 1.57e5

Time

37

Extracted ion tracesExtracted ion traces give better S/N removing background Separating co-eluting peaks

Extracted ion traces can also be used for: PEAK TRACKING ACCURATE QUANTITATION

38

Peak TrackingTIC of explosives mixture

100

0.52

TIC 2.21e6

Which one is HMX?% 3.25 1.67 2.00

3.82

5.65 5.72 5.59

5.81 4.95 4.25

0

1.00

2.00

3.00

4.00

5.00

6.00

Time

39

Peak TrackingMass spectrum of HMX100 84

89 %

113 237

72 59 0 40 60 80 100 120 69 106

131 158 140 160 180

205 m/z 260

200

220

240

40

Peak Tracking

100

2.00

%

Mass Chromatogram m/z 2370.52 3.82 5.65 5.81 1.672.00 3.25 4.95 4.25

0 100

%

TICTime 6.00 7.00 8.00 9.00

0 1.00 2.00 3.00 4.00 5.00

41

Data View - Options

Total Ion Chromatogram The best way to view the whole chromatogram and all peaks visible

Extracted Ion Traces The best way to see data from just one compound

42

m/zMS Spectrum

SIC (Selected Ion Chromatogram) TIC (Total Ion Chromatogram) Retention time

43

SCAN mode V m/z V650

SCAN

V50 0.5sec 0.5sec ime44

SIM(Selected Ion Monitoring) mode V m/z SIM100 % 97 85 50

V97 V85

80.0

85.0

90.0

95.0

100.0

0.2sec 0.2sec 0.2sec Time45

Scan & SIM ModeSIM 152 72 54

m/z

TIC : Scan Mode Retention time46

Summary so far...MS detectors acquire mass spectra which can be used for: Molecular weight determination A TIC chromatogram An extracted ion chromatogramImproves s/n Removes matrix Separates co-eluting peaks

47

GCoven MS

48

49

50

liner) 51

52

1.() 2.() 53

54

55

56


The World of Mass Analyzers

Quadrupole RFDC amu Ion Trap RF Magnetic Sector Time of FlightTOF 58

Ion Source Body Lens 1 & 2

Quadrupole

S NA

Phosphor

+ +

PUMP -ve Ion Dynode

S NRepeller Trap Prefilters

+ve Ion Dynode

Source Magnet GC

59


Single Quadrupole Mass Analyzers

61

Quadrupole Arrangement

+/-(U+Vocost)

-/+(U+Vocost)

Ion beam62

+ +

+

Ions scanned by varying the DC/RF voltage across the quadrupoles DC/RF63

100

10

500

64

Quadrupole Illustration of Mass Separation

65

(Scan Mode) Full Scan Library Search SIM (Selected Ion Monitoring) Sequential Full Scan SIM events SIM 66

Full Scan MSQ0 Q1

Q1 M/Z

Q0

Q1

DETECTOR

67

Full ScanR T : 7 9 .9 7 - 8 9 .2 6 8 4 .6 4 N 2 T 9 0 3 L : .7 1 E 7 IC F : M S 3 0 7 0 7 0 4 _ 4 0 7 0 8 1 4 4 3 1 1 0 0 9 5 9 0 8 5 8 0 7 5 7 0 6 5 Relative Abundance 6 0 5 5 8 4 .4 9 5 0 4 5 4 0 3 5 3 0 2 5 2 0 8 4 .1 0 1 5 1 0 5 0 8 0 8 1 8 2 8 3 8 4 T im e (m in ) 8 5 8 6 8 7 8 8 8 9 8 0 .8 1 8 1 .2 4 8 1 .6 1 8 2 .0 6 8 2 .1 9 8 3 .1 6 8 3 .4 0 8 4 .2 6 8 3 .4 7 8 5 .6 2 8 5 .2 9 8 6 .3 2 8 5 .9 5 8 6 .7 1 8 7 .1 4 8 7 .3 7 8 7 .8 0 8 8 .1 1 8 8 .5 3 8 8 .8 9 8 3 .6 3

TIC

9 3 0 7 0 7 0 4 _ 0 4 0 7 0 8 1 4 4 3 3 1 # 1 2 9 9 2 T : + c F u ll m s [ 5 0 . 0 0 - 4 0 0 . 0 0 ] 1 0 0 9 5 9 0 8 5 8 0 7 5 7 0 9 8 .1 6 5 Relative Abundance 6 0 5 5 5 0 4 5 4 0 3 5 3 0 2 5 2 0 7 2 .1 1 5 1 0 8 1 .1 5 0 6 0 8 0 1 0 0 7 0 .0 6 9 .1 8 4 .1 9 9 .1 5 6 .0

R T :

8 4 .6 5

A V :

1

N L :

5 .9 4 E 6 1 7 2 .1

One Click Library Search

Spectrum

1 7 3 .2 1 2 8 .0 1 1 6 .1 1 2 0 1 4 4 .1 1 5 5 .1 1 6 0 1 7 4 .1 1 8 0 2 0 2 .1 2 0 0 2 2 5 .1 2 2 0 m 2 4 6 .1 2 4 0 /z 2 6 9 .1 2 6 0 2 8 1 .0 2 8 0 2 9 8 .9 3 0 0 3 2 7 .2 3 2 0 3 4 0 3 5 5 .0 3 6 0 3 6 3 .0

1 4 2 .1 1 4 0

3 8 6 .1 3 8 0 4 0 0

68

EIC Co-eluting 254.2 100 507.3

100

TIC 1.57e5

% 334.3 194.2 399.7 0 100 200 300 400 500 600 m/z

%100 194.2

%

226.2 0 100 200 300

402.2 460.2 400 500

580.4 m/z 600

0 11.00 12.00

Time

69

co-eluting peaks100 % 0 194.20 6.14e4

Mass 254

254.23 5.81e4

100 % 0

Mass 194

100 % 0

TIC

TIC 1.57e5

Time 10.50 11.00 11.50 12.00 12.50

70

Improving Sensitivity

Single Ion Monitoring Multiple Ion Monitoring

71

SIM MIM SIM Set quadrupole to pass a single characteristic ion during a retention time window in the chromatogram 10100 Increases sensitivity 10-100X Lose spectral specificity72

SIM MIMMIM 25 Monitor 2 to 5 characteristic ions in addition to SIM quanitiation ion Set acceptable qualifier ion ratios to confirm detection More qualifier ions boost confidence but reduce sensitivity gains73

SIM MS/MS

74

Ions

of all m/z stored until time to detect

External Ionization Ion Trap Mass Analyzer

Step 2 - Ion Ejection Step 1 - Store Ions75

Basic Steps Mass-selective Ejection

Ion Injection

Ion Trapping

7

76

Scan functions

Full Scan

SIM (Selected Ion Monitoring)

MSn Isolate a parent ion and fragment to form daughter ions.

77

Full Scan MS

1. Inject

2. Detect

78

Single-Ion Monitoring (SIM)

1. Inject

3. Detect

2. Isolate

79

Isolation of Ionsqz (wo) Ions at different qz values oscillate at different frequencies (wo)

qz0.0 0.9087

o 80

q z 2 2

Analytical Benefits of MS/MS Increased selectivity Concentration of analyte too low Chemical interferences too high (complex matrix)

Structural characterization Provides information about chemical structure of unknown compounds

Ease of use Routine GC/MS/MS is as practical as GC/MS81

What is Sensitivity? Sensitivity is a function of the Signal to Noise Signal/Noise = Sensitivity To improve Sensitivity Increase Signal or Reduce Noise82

How we improve Sensitivity

S/N Sensitivity Quadrupoles use SIM to increase S Ion trap uses MS/MS to reduce N

83

84

MS/MS 1. Inject 3. Fragment

2. Isolate

4. Detect

85

MS/MS EI EI MS/MS

Isolation Event

Collisional Activation Event86

MS/MS Analytical BenefitsIncreased selectivity Advantageous when concentration of analyte is low compared to chemical interferences (complex matrix)

Structural characterization Provides information about chemical structure of unknown compounds

Ease of use Routine GC/MS/MS is as practical as GC/MS87

MS/MS

MS Less sensitive than MS Can only analyze for target analytes

88

GC/MS Ion Trap (MSn) Scan MS/MS

SIM MS/MS

89

Should I sell Single Quadrupole of Ion Traps?

ISQ

ITQ 1100 GC/MSn

90

Table of ContrastsIon TrapsMass Separation in time High sensitivity Full Scan Selectivity of MS/MS

Single QuadrupolesMass Separation in space Lower sensitivity Full Scan High sensitivity SIM Library Search

91

Outcomes of ContrastsIon TrapsMass Separation in Time High sensitivity Full Scan by Trapping over Time Lower sensitivity SIM Multiple stages of MS For Confirmation/ And Structure Elucidation92

Single QuadrupolesMass Separation in Space Allows for Fast GC Lower sensitivity Full Scan High sensitivity SIM By scanning a single ion over time No multiple stages of MS

Thank you for your attention

93

introduction of gc-ms

Documents