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By now, your pastel-colored basket filled with jelly beans, Bunny Mix M&M’s, Cadbury Creme Eggs and maybe even a Peep or two is becoming a thing of the past. But before you enjoy what’s left of your holiday candy, let’s use a few pieces to conduct a sweet experiment! In this week’s Saturday Science from LiveScience, find out which dyes the candy makers used to make your favorite candies so colorful!
Materials:
- 15 pieces of hard-shell, colorful candies (such as M&M’s): 5 each of 3 different colors you wish to test
- Coffee filters
- Scissors
- Pencil
- Ruler
- Pie plate or jar lid
- Transparent plastic cup or clear drinking glass
- Disposable pipette or clean eyedropper
- 4 wooden or plastic coffee stirrers
- Measuring cup and measuring spoons
- Container large enough to hold 4 cups of water
- Wide-mouth glass jar
- 2 mini binder clips
- Red, green and blue food coloring
- Salt
- Water
Process
Prepare your test strips:
- Cut coffee filters into 30 test strips that are 1 inch by 3 inches.
- Use a pencil to lightly label each strip: 3 strips for each color of candy and 3 strips for each color of food coloring.
- Draw a light pencil line across the width of each strip about half an inch from the bottom. This will be the starting line for your test drop of candy dye.
Extract dye from candies:
- Put some water in a cup. Use the eyedropper to move a single drop of water to the pie plate. Carefully set a single candy in the drop of water. Let rest for at least three minutes while the dye dissolves out of the candy into the water.
- Remove and discard the candy.
- Touch the tip of a coffee stirrer to the colored drop and transfer a droplet of colored water to the middle of the starting line on the appropriate test strip. Allow the droplet to dry completely.
- Repeat step “c.” three more times. You are layering a total of four drops of dye on your starting line.
- Prepare four more test strips with identical candies (for example, a total of 5 test strips prepared from 5 brown M&M’s).
- Prepare 5 test strips for each type of candy you are testing.
- In a similar manner, prepare 5 strips for each of the colors of food coloring. These will be your “known” dye colors. Later you will be comparing the strips prepared from the candy dyes to the dyes in these “known” colors.
Prepare the solvent:
- Dissolve 1/8 teaspoon of salt in 4 cups of water.
- Stir until the salt is completely dissolved.
Do the chromatography:
- Pour a small amount of the salt solution into the bottom of a transparent cup or drinking glass.
- Clip two chromatography strips to a coffee stirrer and balance the stirrer across the top of the cup or drinking glass. The strips should hang down into the glass.
- If needed, add more salt solution so the bottom edge of the test strip just touches the surface of the solvent (the salt water). Your starting line with the drop of color should be just above the surface of the salt water.
- Allow the solvent to creep up the strip by capillary action, carrying dye with it until it is half an inch from the top of the strip.
- Allow the test strips to dry. Use a pencil to mark how far the dye traveled up the strip.
- Compare the dyes extracted from the candy to the “known” food color dyes. What colors do you see on the chromatogram?
Summary
When you compared the dyes extracted from the candy to the food coloring dyes, could you tell which food dyes were used to color the candy?
If you answered yes, great job! You properly separated the different colors that make up the candies’ dyes. This process of separating different components of a mixture is called chromatography. According to LiveScience, when you added the test strip to the solvent, the mixture separated and the components flowed up the paper at different rates. The pattern that the separated substances made is your "chromatogram,” which you can now use to determine which dyes were used to make your candy colorful!
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