Basics of spectrophotometry

This kit will allow you learn about the nature of light, the spectrum and colors. Transmission and absorption of light by chemicals diluted in a liquid, Beer-Lambert law.

We will use a spectrophotometer to measure how colored food dies absorb light at different wavelengths. We will create a calibration curve, and use it to find out the concentration of a mystery sample.

We will cover the following theoretical subjects:

  • The Nature of light. Spectrum, wavelengths and colors.

  • How chemicals absorb light, and how we can use this properly to determine their concentration.

  • Transmittance, Absorbance, Beer-Lambert law.

For the practical part, we will use a DI-Lambda spectrophotometer and food-safe dies to demonstrate these principles.

  • We will measure which wavelengths of light are absorbed by dies of different colors, and which ones can pass through.

  • We will make serial dilutions of a food die to create a calibration curve.

  • We will measure the absorbance of a mystery sample and find out its concentration using the calibration table.

Optional: Use Excel to fit a line to the calibration curve, and to calculate the absorbance of the mystery sample with more precision.

Kit contents

This kit is intended for a classroom of up to 30, working in groups of 2-3 students.

It includes:

1 2
Food-safe color dies 25mL 2x red , 2x green, 2x yellow, 2x blue
Distilled water 100mL 2x
Plastic spectrophotometry cuvettes 50
Plastic pipettes 1mL 50
Printed materials for teachers 2x (free download)
Printed materials for students 10x (free download)
You will also need