Analysing substances

Substances can be analysed using a variety of methods including paper chromatography, gas chromatography and mass spectrometry.

Methods of analysis

Chemists can use many different methods to analyse substances. Some methods rely on chemical analysis, while others rely on machines.

Paper chromatography

Paper chromatography is used to analyse coloured substances, such as the coloured pigments in plants and artificial colours used as food additives.

Paper chromatography works because some of the coloured substances are better at dissolving in the liquid than they are at bonding with the paper, so they travel further up the paper.

The animation shows what happens during paper chromatography.

Chromotography

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Two substances are likely to be the same if they have the same colour and they travel the same distance up the paper.

Instrumental methods of analysis

Instrumental methods of analysis rely on machines. There are several different types of instrumental analysis. Some are suitable for detecting and identifyingelements, while others are better suited to compounds. In general, instrumental methods of analysis are:

• Fast
• Accurate (they reliably identify elements and compounds)
• Sensitive (they can detect very small amounts of a substance in a small amount of sample)