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Quantitative Determination of Food Dyes


Learning Objectives:

Students use Beer's Law and the technique of spectrometry to determine the amount of food dye present in powdered drink mixes.

Procedures:

Students first use spectrometry to acquire the spectra of three food dyes; FD&C Yellow 5, FD&C Red 40, and FD&C Blue 1. In doing so, they find the wavelength at which each absorbs a maximum amount of light. Next, they construct a standard calibration curve for each dye from a series of solutions of known concentrations. They can use the formula of this curve to quantitatively determine the amounts of these food dyes present in any other solution.