InstrumentationDeals with the theoretical and practical aspects of different instruments and instrumental techniques involved in Analytical Chemistry,

Which is a branch of chemistry involving separation, identification and determination of components of a sample

1 M = 1 mole/1 liter solution

Classification of analyteClassification of analyte

• Major component 1-100%Major component 1-100%

• Minor component 0.01 to <1.00%Minor component 0.01 to <1.00%

• Trace component 1ppb – 100 ppmTrace component 1ppb – 100 ppm

• Ultra-trace component <1ppbUltra-trace component <1ppb

Analytical method on the basis of Analytical method on the basis of sample sizesample size

MethodMethod Weight mgWeight mg Volume µlVolume µl

MesoMeso >100>100 >100>100

Semi-microSemi-micro 10-10010-100 50-10050-100

MicroMicro 1-<101-<10 <50<50

Ultra microUltra micro <1<1

Problems•Prepare a solution of 1 Molar HCl

•Prepare a solution of 1 Molar NaOH

•Prepare a solution of 1 Molar H2SO4

•Prepare a solution of 1 Molar Oxalic acid dihydrate

•Prepare a solution of 1 Normal Oxalic acid dihydrate

Problem

• You have a stock solution of NaOH having concentration of 1 M, prepare 500 mL solutions of 0.1N, 0.2N, 0.3N using dilution equation

Problem

•What is pCl and pNa of a 5.00g/L solution of NaCl?

Na Cl NaCl Given Molar pNa/pCl

23 35.5 58.5 5g/L0.08547

0 1.068186

Selecting an Analytical Selecting an Analytical TechniqueTechnique1. What accuracy and precision is 1. What accuracy and precision is

required?required?2. How much sample is available?2. How much sample is available?3. What is the concentration range of the 3. What is the concentration range of the

analyte?analyte?4. What components of the sample cause 4. What components of the sample cause

interference?interference?5. What are the physical and chemical 5. What are the physical and chemical

properties of the sample matrix or properties of the sample matrix or interfering species?interfering species?

6. How many samples are to be analyzed?6. How many samples are to be analyzed?

Defining the problem first:

Numerical Criteria for Selecting Analytical Numerical Criteria for Selecting Analytical TechniqueTechnique

1. Precision1. Precision2. Bias 2. Bias ((A systematic error occurring in a A systematic error occurring in a

chemical measurement that is inherent in the chemical measurement that is inherent in the method itself or caused by some artifact in the method itself or caused by some artifact in the system, such as a temperature effect)system, such as a temperature effect)

3. Sensitivity (LOD and LOQ)3. Sensitivity (LOD and LOQ)

4. Detection Limits4. Detection Limits

5. Concentration Range5. Concentration Range

6. Selectivity6. Selectivity

Other Characteristics to Be Other Characteristics to Be Considered in Method of ChoiceConsidered in Method of Choice

1. Speed1. Speed

2. Ease and Convenience2. Ease and Convenience

3. Cost and availability of instrument3. Cost and availability of instrument

4. Per-sample cost4. Per-sample cost

SamplingSampling•Homogeneous materials Homogeneous materials (grab sample, (grab sample,

random)random)

•Heterogeneous materialsHeterogeneous materials (Several (Several samples are required) that includesamples are required) that include

1- Gross sampling1- Gross sampling2- Laboratory sample (taken from gross sampling 2- Laboratory sample (taken from gross sampling

and homogenized)and homogenized)3- Analysis samples (taken from laboratory sample)3- Analysis samples (taken from laboratory sample)4- Biological fluids (sampling time and 4- Biological fluids (sampling time and

preservation)preservation)5- Storage of the samples (suitable containers, low 5- Storage of the samples (suitable containers, low

temp)temp)6- Urine samples (acidified pH4.5) 6- Urine samples (acidified pH4.5)

Preparation of samples Preparation of samples

• Weighing of the sampleWeighing of the sample

• Samples are prepared in replicatesSamples are prepared in replicates

• Solid samples must be dissolvedSolid samples must be dissolved

• Ashing or digestion for trace metalsAshing or digestion for trace metals

• Preparation of blankPreparation of blank

Chemical separationChemical separation

• Includes precipitation, extraction, Includes precipitation, extraction, chromatography, dialysis and chromatography, dialysis and distillation,distillation,

andand

1- Eliminates interferences (analyte 1- Eliminates interferences (analyte away from matrix)away from matrix)

2- Provides suitable selectivity in 2- Provides suitable selectivity in measurementmeasurement

Classification of Analytical Classification of Analytical MethodsMethods

1-Classical methods1-Classical methods– GravimetricGravimetric– TitrimetricTitrimetric

2-Instrumental methods2-Instrumental methods– SpectroscopySpectroscopy– ElectroanalyticalElectroanalytical– ChromatographyChromatography

Data AnalysisData Analysis• The concentration of analyte in the sample The concentration of analyte in the sample

solution is used to calculate the solution is used to calculate the concentration of analyte in the original concentration of analyte in the original sample, and is expressed in relative termssample, and is expressed in relative terms

• Precision is expressed by SD of RSDPrecision is expressed by SD of RSD• FinallyFinally

Critical evaluation of results (To see Critical evaluation of results (To see whether results relate to the analytical whether results relate to the analytical problem, as stated before the experiment problem, as stated before the experiment