Analysis of Food Dyes in Beverages

Product Details

Big Idea 1, Investigation 1, Primary Learning Objective 1.15

Food dyes are everywhere—from food to drink to cosmetics! How much food dye is actually contained in these products? This advanced-inquiry lab allows students to utilize spectroscopy and graphical analysis to determine the concentration of dye in a sports drink.

The lab begins with an introductory activity in which students prepare a series of standard dilutions of an FD&C Blue 1 stock solution. Students then measure the percent transmittance of each and graph the results to identify an optimum linear relationship among various functions (T, %T, log T and A) for a Beer’s law calibration curve. A Beer’s law plot of absorbance as a function of concentration may then be used to calculate the concentration of any “unknown” solution. Using this introductory procedure as a model, students design guided-inquiry experiments to determine the concentration of food dye(s) in sports drinks and other consumer beverages. Additional dyes (FD&C Yellow 5 and Red 40) and samples of sports drinks are included in the kit for optional extension or cooperative class inquiry studies.

Use this investigation to develop—and test—skills in preparing accurate serial dilutions, understanding spectroscopic measurements and extrapolating from graphical data.

Complete for 24 students working in pairs. Refill kit includes chemicals and consumable items. A version of this lab is available as a Wet/Dry Advanced Inquiry Laboratory Kit for One Period (Catalog No. AP8497).

2024 CED Alignment:  

Unit 3 - Properties of Substances and Mixtures  

Topic 3.13 - Beer-Lambert Law 

Description of the Lab  

Students apply Beer's Law to determine the concentration of FD&C dyes in commercial beverages. This lab helps them connect spectrophotometric data to real-world chemistry and reinforces careful graphing and quantitative analysis. 

Learning Objective 

• LO 3.13.A – Explain the amount of light absorbed by a solution or molecules or ions in relationship to the concentration, path length, and molar absorptivity. 

Skills Students Will Learn 

• 3.A – Represent chemical phenomena using appropriate graphing techniques, including correct scale and units. 
  In this lab: Students generate and interpret a calibration curve for dye concentration. 

• 5.F – Calculate, estimate, or predict an unknown quantity from known quantities by selecting and following a logical computational pathway and attending to precision (e.g., performing dimensional analysis and attending to significant figures). 
  In this lab: Students calculate unknown dye concentrations using Beer's Law. 

• 6.B – Support a claim with evidence from experimental data. 
  In this lab: Students justify conclusions about concentration based on absorbance data.