Chapter 1: What is chemical analysis?
Where is chemical analysis important? To know accurately what chemicals are in something is a right that
today is taken for granted. This ranges from products we buy to substances that are found in the
environment.
The manufacturer and the consumer have an obvious interest in the chemical composition of the
product, and would expect control measures to be adequate and appropriate for maintaining its
composition. Control measures include process control (monitoring steps in the chemical manufacturing
process) and quality control (monitoring final product).
Government agencies employ chemists who check the quality of products and the environment to make
sure that the products conform to legislative requirements that ultimately protect the community. These
chemists determine what chemical and how much is in a product. They may verify that certain substances
are not present or that they do not exceed set maximum limits.
Analytical chemists use a range of techniques and technologies to determine the identity, quality and
quantity of the chemicals that make up our world.
Chemical Analysis seeks to answer two questions:
 What chemicals are present in the substance? (Qualitative Analysis)
 How much of each chemical is present? (Quantitative Analysis)
Qualitative Analysis:
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Can identify the types of chemicals present in a substance
Give information about the structure of newly discovered compounds
Quantitative Analysis:
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Provides information about the amount of chemicals present in a substance
Often includes stoichiometry, determining number of moles
The most appropriate analytical technique to use depends on factors including:
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The nature of the sample
The nature of the chemical under analysis (how it reacts)
Concentration of the chemical
Accuracy required
Time available
Cost and benefit in carrying out analysis
Your Turn – Classify the following as qualitative or quantitative types of analysis:
a) A pregnancy test in which a chemical is added to a sample of urine and a colour change is sought
b) A chlorine test in which the colour of a chemical is compared against reference standards to
estimate the chlorine level in a home swimming pool
c) Placement of a detector in the exhaust pipe of a car during a tune-up procedure to measure the
level of carbon monoxide levels
d) Testing for monosodium glutamate (MSG) in a sample of food claimed to be MSG free
It may be possible to analyse the same chemical by a range of chemical techniques, each adding a
different piece of information. A number of the techniques are often combined in a single instrument to
give a more sensitive or faster analysis.
Gravimetric Analysis
Titrations
Atomic absorption
spectrometer
High performance Liquid
Chromatography
UV Spectrometer
Technique
Gravimetric analysis
Physical/Chemical Property
Analysis by mass
Mass of chemical, isolated from a
mixture or precipitated in a reaction
(Ch 2)
Acid-Base Titrations
(Ch 4)
Redox Titrations (Ch 5)
Paper
Thin-layer
Gas
High Performance Liquid
(Ch 6)
Flame tests
Atomic Emission (AES)
Atomic Absorption (AAS)
Ultraviolet-visible (UV)
Infrared (IR)
Nuclear-magnetic resonance
(NMR)
(Ch 7)
Mass spectrometry
Example of Analysis
Percentage of stored in a silo
Concentration of salt in jar food
Volumetric Analysis
Neutralisation reactions by acid or base
Reactant as oxidant or reductant
Chromatographic Analysis
Adsorption onto a stationary phase and
solubility in a mobile phase
Concentration of Ammonia in window cleaner
Concentration of Hydrogen Peroxide in hair
bleach
Analysis of codeine in tablet
Concentration of alcohol in blood
Spectroscopic Analysis
Absorption or emission of part of the
electromagnetic spectrum
Mass Spectrometry
Mass/charge ratio of ionised compound
(Ch 8)
Monitoring levels of Ca in blood (AES)
Conc. Of Cu in “gold” bracelet (AAS)
Amount of Aspirin in tablet (UV)
Determine structure of new drug (IR, NMR)
Identification of lead isotope ratios in
meteors
Identification of structure of new types of
drugs
Chapters 3 – 5 are described as ‘wet chemical techniques’. They can be carried out using simple equipment in a laboratory.
Chapters 6 – 8 look at instrumental methods of chemical analysis.