Science Project Using Paper Chromatography

Goal of this project is to use paper chromatography to see which dyes are used in the coatings of your favorite colored candies.

Why do different compounds travel different distance on the piece of paper?

How is an Rf value useful?

What is chromatography used for?

Candy with colored coatings- Skittles and M & M’s

At least 30 strips of paper- coffee filters or chromatography paper 3 cm by 9 cm

Wide-mouth jar

Pencil

Ruler

Tape

Water

Toothpicks

Food coloring ( red, green and blue)

1. Do your background research so that you are knowledgeable about the terms, concepts and questions above.

2. Use a pencil to lightly label which candy color or food coloring will be spotted on each paper strip.

3. Draw a pencil line 2 cm from the edge of each strip of paper.

4. Next you need to extract some dye from each candy you wish to test. Set the candy down on a clean plate in a drop of water. Leave it for a minute to allow the dye to dissolve. Remove candy, then dip a clean toothpick into the now-colored drop of water. Spot the candy dye solution onto the chromatography paper by touching the toothpick to the chromatography strip, right in the center of the origin line. Allow the spot to dry, then repeat the spotting at least three more times. You want to make sure to have enough dye on the chromatography paper so that you can see the dye components when they separate out on the paper. Make five separate strips for each candy you want to test.

5. Repeat step 4 for each color of candy you want to test ( at least three different colors).

6. You also need to prepare chromatography strips with food coloring dyes. These will be your known compounds, with which you will compare the “unknown” candy dyes. For each food coloring color, use the same procedure as in step 4. You’ll use a drop of food coloring as the source for dipping your clean toothpick.

7. Prepare a 1% salt solution for the chromatography solvent. Add 1/8 teaspoon of salt to 3 cups of water ( 1g of salt to 1L of water). Shake or stir until the salt is completely dissolved.

8. Pour a small amount of the salt solution into the wide-mouthed jar. You’ll tape the strip to a pencil and rest the pencil on top pf the jar so that the strip hangs into the jar.