Qualitative and Quantitative Analysis of Food Dyes >> Step 4 : Part 1

Qualitative and Quantitative Analysis of Food Dyes

Step 4 - Part 1: Determining the concentration of the unknown dye


You are now ready to prepare a 50 mL sample of your drink according to the package instructions. You will then transfer about 10mL of this solution to a vial for the colourimetric measurement. The measurement can be performed on a mixture of dyes provided the analytical wavelenghts of the two dyes present in the drink are far apart.

In this step you will measure the absorbance of the dye, Blue #1. In the next part, you will repeat the calibration and the absorbance measurements for the red dye component of the drink.

The instructions on the packet are: dissolve the content of the package (6g) in 2L of water.

How many g of the powdered drink are required to prepare 50mL of this drink according to the package instructions? (see calculation below)



Once the drink has been prepared, the vial is measured in the colourimeter. Use the colourimeter simulation below to measure the absorbance of the unknown sample (purple vial). Once you have measured the absorbance of your sample, use your graph to determine the concentration of the solution and enter your answer into the question below the simulation. If you get stuck, tutors are included to walk you through determining the concentration of your drink sample.

Now that you have measured the absorbance of your sample, use your graph to determine the concentration of the solution and enter your answer into the tutor below.

The following tutors are a step by step walkthrough that show the details on how to solve the above problem.