KECS9B: Forensic analysis of food dyes can be used to determine the mix of coloured substances in certain food drinks such as sports drinks.

Curriculum Topics
Chemistry: Properties and structure of materials
Chemistry: Properties of pure substances and mixtures

Description
Forensic analysis of food dyes can be used to determine the mix of coloured substances in certain food drinks such as sports drinks. This can be useful in an investigation that seeks to find the source of certain contaminants or “poison” that is believed to be contained in a sports drink. The colour of the sports drink could conceal the contaminant but spectroscopy can reveal the contents and identify the contaminant.

Principle
Food dye colours have a characteristic absorption peak that can be used as an identifier. Other coloured solutions also have characteristic peaks that can also act an identifier. In this case comparison of absorption graphs can be used to identify possible components of a solution.

Tasks
1. Measure and analyze the visible light absorbance spectra of samples of aqueous food dye mixtures to determine the absorbance spectrum for each sample.
2. Use the absorbance spectra graphs of food dyes to determine the composition of the colouring agents in samples of sports drinks.
3. Determine which sports drink contains “poison” food colouring solution.

Ideas for Extended Investigations
1. Develop a procedure using a spectrophotometer that could be used to determine the concentration of food colouring in a sample.
2. Investigate the role of other ingredients in a sports drink sample in determining the concentration of food dye colour.

Last edited 22nd Aug 2018