CHE301 Handouts

Topic 1:

Introduction-I

• Study of methods for determining the composition of substances
• qualitative (what?)
• quantitative (how much?)
• Chemical analysis includes any aspect of the chemical characterization of a sample material.
• Analytical Chemistry is basically study of testing methods for determining composition of substances. This determination may be limited to qualitative results or quantitative estimation. Qualitative means what substances are present in composition.
• Whereas the percentage of components in a mixture is called quantitative estimation.
• Chemical analysis includes any aspect of chemical characterization, starting from collection of sample, extraction, sample preparation, instrumental analysis to statistical evaluation of collected data.

Detection / Qualitative:

Does the sample contain substance X?

Identification / Qualitative:

What is the identity of the substance in the sample?

Estimation / Quantitation:

How much of substance X is in the sample?

Separation:

• How can the species of interest (analyte) be separated from the sample matrix for better quantitation and identification? Quality control in the

process industries

• of starting materials
• of intermediates
• of products
• Environmental analysis
• Monitoring and control of pollutants
• Clinical and biological studies
• Measurement of nutrients
• Measurement of drug levels in body fluids
• Geological assays
• Measurement of metal concentrations in ores and minerals
• Determination of oil/gas concentrations in rocks
• Fundamental and applied research
• Chemical engineering: how much conversion (or separation) do we obtain under specific conditions?
• Organic molecule synthesis: what compound have we made?

Topic 2

Introduction-II

In this module we will discuss about steps in analysis.

We must understand here the two terms; matrix and analyte An analyte, component (in clinical chemistry) or chemical species, is a substance or chemical constituent that is of interest in an analytical procedure.

While in chemical analysis, matrix refers to the components of a sample other than the analyte of interest. The matrix can have a considerable effect on the way the analysis is conducted and the quality of the results obtained; such effects are called matrix effects.

• Sampling

• Grab and composite
• Types of sampling pattern
• Sample preparation
• Dilution / concentration
• Wet digestion
• Dry ashing
• Selection of Analytical Methods
• Standard analytical methods

Validated Method

First step in analysis is Sampling. The results of your analysis simply depend upon the sampling. Sampling technique, sampling type and sampling pattern depend upon the matrix, location, variability of constituents, bulk of bags or product etc.

Sample may collect at some particular time and location are called grab sample or many grab samples may combine to form composites.

From 100 of Kg, 1000 of litters or acres of land we collect the sample in grams. And to analyse we have to finalize just 2-3 gram of sample, or maximum 100 mL of liquid. Some time sample need dilution while some time we have to concentrate a sample. To analyse we have to digest or extract our analyte from the sample. This is called sample preparation.