Budi Hastuti, S.Pd., M.Si.

INTRODUCTION

Two step analysis:

1. Identify Qualitative Analysis2. Estimation Quantitative Analysis

Method Classical / conventional Modern

Analytical scale Macro, semimakro Ultramikro,Micro

Submikro

ANALYSIS covers 3 aspects comprehensively:1. Data collection2. Data processing, interpretation3. Judgement, decision making / conclusions

Analytical Chemystry is a science that identify the types of components in a sample (qualitative analysis) and determine the relative amounts of each component (quantitative analysis).

Generally, phase separation is necessary to isolate the components in the samples analyzed.

The method used distinguished role in 2 groups namely: Classical Methods Instrumental Methods

CLASSICAL METHODS - also called wet method

1. Separation of analytes - extraction, distillation, precipitation (precipitation), filtration (filtering), etc..

2. Qualitative Analysis - boiling point, freezing point, color, odor, density, reactivity, refractive index, etc..

3. Quantitative Analysis - gravimetric and volumetric analysis.

The classic analytical The modern analytical Long way since the beginning

of analytical chemistry

Dispensable complicated tools

sufficient sample quantaty is needed (macro, semi-macro)

Based on chemical reactions and the Stoichiometry equation

based of matter-matter interactions

A new way, consistent development of science and technology

It takes more complicated contraption

small sample size (micro, ultramikro, submikro)

Based on the measurement of physical quantities of non stoichiometry

Based of energy-matter interactions

Sensitive Fast Selective and specific Objective Often non-destructive Easily automated

expensive tools Utilization and complexmaintenance Need a special technician Need additional tools, calibration and

standardization of cheese (sometimes difficult)

needs a good environment

Instrumental Methodexploit the physical properties of an analyte to obtain information, both qualitative and quantitative.

Separation of analytes- Can be done in 2 ways:a. Physical separation: - Chromatography - Electrophoresisb. Spectroscopic separation: isolate the signal that appears in spectroscophy

Instrumental Method1. Separation of analytes2. Qualitative Analysis * X-Ray Spectroscopy * Infrared Spectroscopy (IR) * mass spectroscopy (MS) * nuclear magnetic spectroscopy (NMR)3. Quantitive Analysis * UV-Vis Spectroscopy *  Atomic absorption & emission spectroscopy

(AAS and AES) * mass spectroscopy (MS) * Conductivity (pH)

Type method of Instrumental

To determine the appropriate analytical method (the best), the analyst should ask the following things:

a. Is accuracy required?b. How many samples are available?c. How much range of concentrations found in the sample?d. Are there any components in the sample that cause interference?e. How physical and chemical properties of the matrix contained in the sample?f. How many samples to be analyzed?

Performance characteristics

Precision Absolute standard deviation Relative standard deviation Coefficient of variation Variance

Accuracy/Bias Absolute systematic error Relative systematic error

Sensitivity Calibration Analytical

Detection Limit Blank plus three times Std.

Dev. of blank Limit of Linearity (LOL)

Selectivity Effects of interferences Coefficient of Selectivity

The criteria used to compare several analytical methods

The other criteria that need to be considered in the selection of analytical methods:

a Velocity analysis b Convenience analysismethods c Operator skill level d Cost and availability of equipment

(instruments) e Cost of analysis every sample

Performance characteristics1. PRECISION

Measure reproducibility of a determination set

a) a) Absolute standard deviation (Absolute standard deviation (ss)) 1

)( 2_

1

N

xxs

N

i

i

_xsRSDb) b) Relative standard deviation (Relative standard deviation (RSDRSD))

%100 _ xsCVc) c) Coefficient of variance (Coefficient of variance (CVCV))

/ nsSEc) c) Standard error of mean (Standard error of mean (SESE))

Performance characteristics2. ACCURACY (BIAS)

Measure the error of an analytical method.

a) a) Absolute bias (Absolute bias (EEaa)) xEa

100 Error %

xa) a) Persen bias (Persen bias (% error% error))

Performance characteristics3. SENSITIVITY

The ability to distinguish effect of increasing concentration on instrument response.

SS = signal or instrument response = signal or instrument responseSSblbl = signal from blank sample = signal from blank samplecc = sample concentration = sample concentrationm m = = calibration sensitivitycalibration sensitivity(slope of calibration curve)(slope of calibration curve)

a)a) Calibration sensitivity (Calibration sensitivity (mm)) blSmcS

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1Concentration (c )

Sign

al (S

)

m2

m1

Sbl

Sm1

C

Sm2

b)b) Analytical sensitivity Analytical sensitivity (()) Ss

m

= analytical sensitivity= analytical sensitivitym = calibration sensitivitym = calibration sensitivityssSS = std. dev. in signal measurement = std. dev. in signal measurement

Performance characteristics4. DETECTION LIMIT

Concentration / minimum analyte mass that still can be detected (still can be distinguished from the noise) by a analysis method based on certain confidence level (usually 95%)

a)a) Minimum detectable signal (Minimum detectable signal (SSmm) )

blblavgm ksSS ,

SSmm = minimum detectable signal= minimum detectable signalSSavg,blavg,bl = = average signal of the blankaverage signal of the blankssblbl = = standard deviation in the blank signal standard deviation in the blank signalk k = multiple of variation in the blank signal= multiple of variation in the blank signal

• • The analytical signal must be larger than the blank signal (The analytical signal must be larger than the blank signal (SSavg,blavg,bl) by some factor () by some factor (kk) of ) of the standard deviation in the blank (the standard deviation in the blank (ssblbl). ). kk is usually set to a value of three.is usually set to a value of three.

b)b) Minimum detectable concentration (Minimum detectable concentration (ccmm) )

• • Limit of Detection (Limit of Detection (LODLOD)) mSS

c blavgmm

, ccmm = minimum detectable concentration= minimum detectable concentration

mm = slope of the calibration curve = slope of the calibration curve • • Expressed in terms of Expressed in terms of ssblbl

mksc bl

m

Performance characteristics5. SELECTIVITY

Degree an analytical method is free from interference that contained on the sample matrix

S

cA

Sbl

mA = slope

mB = slope

mC = slope

cB cC

)(

/

/

,, blCACBABAA

, ACAC

, ABAB

blCCBBAA

SckckcmS

mmk

mmk

ScmcmcmS

k is the selectivity coefficient

K value ranging from 0 (not selective) up to a certain figure. Increase k, the methods more selective