S.O’Brien
Donald High School
Year 12 Chemistry Chapter 1: What is Chemical Analysis?
1.1 Chemical analysis
The packaging on any processed foods must contain a label that provides you with
nutrition information so you can make healthy diet choices. This information comes from
chemical analysis.
Figure 1: an example of what is included on food labels and how they are recorded.
Analytical chemists are employed in a range of industries, from food manufacturing to
environmental monitoring and forensic science. They use a range of techniques and
technologies to determine the identity, quality and quantity of the chemical that make
up our world.
Chemical analysis is used to answer many other important industrial and environmental
questions.
 Is the amount of mineral in this ore body high enough to make the mine
profitable?
 What mineral deficiencies does this soil have? What type of fertiliser is needed
and how much should be added to address this problem?
 Is the sugar content of my grapes high enough to make a quality wine?
 What additives have been added to this food? Does the amount comply with
those specified in the food standards?
Chemists can answer these questions by analysing food and other substances to
determine their composition.
S.O’Brien
Donald High School
1.2 Quality control
In most processes that convert raw materials into a manufactured product, information
is needed about the composition of the raw materials and also about the final product.
So that quality of the final product is consistent.
Chemists have developed methods to determine the composition of the raw materials
and the quality of the final product. These are methods of quality control.
Chemical analysis of the chemical composition of a substance 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: identification of chemicals in plant extracts
The fragrant oils of many eucalypt species were first extracted by Australian settlers
in the 1800s. These pioneers found that the oils could be used as perfumes and
disinfectants, and they are still widely used for those purposes today. The identification
of substances present in plant oils is one example of qualitative analysis. Chemists are
now investigating some of the plants used in the bush medicines of Aboriginal people and
early settlers.
Qualitative analysis can identify the types of chemicals present in a substance. It can
also give information about the structure of newly discovered compounds such as
potential new drugs.
Analytical techniques are used to separate, identify and determine the composition and
structure of biologically active compounds that may be used as drugs or medicine.
Quantitative analysis aflatoxins in peanuts
A common mould that grows on nut and cereal crops produces substances known as
aflatoxins. Aflatoxins are amoung the most powerful cancer-causing substances known.
In Australia, the National Health and Medical Research Council has set a maximum
permitted level of aflatoxins of 15 g/kg in peanuts and products such as peanut butter.
Analytical techniques such as gas chromatography, liquid chromatography and mass
spectrometry are used to measure the level of aflatoxins in peanuts.
Question: 1
1.3 Analytical techniques
The most appropriate chemical technique to use depends on factors including the nature
of the sample, the nature of the chemical under analysis, the concentration of that
S.O’Brien
Donald High School
chemical, the accuracy required, the time available, and, not least, the cost and benefits
in carrying out the analysis.
Many different chemical and physical properties can be used as a basis for qualitative
analysis. These properties are then compared with the properties of known substances.
Summary of Techniques
Technique
Analysis by mass
Gravimetric analysis
Volumetric analysis
Acid-base titration
Redox titrations
Chromatographic analysis
Paper
Thin-layer
Gas
High Performance Liquid
Spectroscopic analysis
Flame tests
Atomic emission (AES)
Atomic absorption (AAS)
Ultraviolet-visible (UV)
Infrared (IR)
Nuclear magnetic resonance (NMR)
Mass spectrometry
Physical or Chemical Properties
A number of the techniques listed above are often combined in a single composite
instrument to give a more sensitive or faster analysis.
Questions: 2, 5 & 8
Summary notes: should already be written for this chapter
 Objectives
 Key terms