Colors of Grape Kool-Aid by Liquid Chromatography

Chemical Technology I – Experiment #3

Introduction

You will be given a solution of Grape Kool-Aid. This solution will be separated into its two (2) colored components using a Waters Sep-Pak C18 cartridge.

Procedure

1. Condition the Sep-Pak cartridge using 10 mL of pure methanol. To do this, simply aspirate 10 mL of pure methanol into the syringe. Place the Sep-Pak onto the syringe (long end towards syringe) and slowly (2 minutes) push the 10 mL of pure methanol through the cartridge. Collect the methanol in a beaker and at the end of the lab discard in the Organic Waste Container under the hood.

2. Remove Syringe from the Sep-Pak and aspirate 10 mL of distilled water into syringe barrel. Replace the Sep-Pak (long end towards syringe) and flush the cartridge slowly (2 minutes) with the 10 mL of water.

3. Remove Syringe from the Sep-Pak and aspirate 2 mL of Grape Kool-Aid into the syringe barrel. Put the Sep-Pak back onto the syringe and very slowly depress the plunger to load the 2 mL of Kool-Aid onto the head of the cartridge bed.

4. Remove Syringe from the Sep-Pak and aspirate 10 mL of 5.0% 2-propanol solution. Put the Sep-Pak back onto the syringe and very slowly (5 minutes) depress the plunger to elute the red food color into a 10 mL beaker.

5. Remove Syringe from the Sep-Pak and aspirate 10 mL of 35.0% 2-propanol solution. . Put the Sep-Pak back onto the syringe and very slowly (5 minutes) depress the plunger to elute the blue food color into a 10 mL beaker.

6. Mix the contents of the 2 test tubes together. Is there any difference between the color of this mixture and the original grape Kool-Aid solution? Which color dye was the least soluble in 2-propanol?

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