How to Do Chromatography Using a Coffee Filter
Chromatography is a method chemists use to separate pigments that have been mixed together to form colored inks or dyes. You can do your own chromatography using coffee filters as the chromatography paper and the inks from black magic markers as your test substances. Chromatography will show you that black ink is really a mixture of red, green, blue and yellow pigments.
Instructions
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Pour about 1/2 inch of water in one cup. Put 1/2 inch of alcohol in the other cup.
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Flatten some coffee filters and smooth out the ridges. Cut some 1-inch strips out of the middle sections of the filters.
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Put a sample dot of ink from each marker at the bottom of a filter strip (one dot per strip). Make the dot about 1/2 an inch from the edge of the strip. Keep track of which samples are from water soluble markers and which ones are from permanent markers.
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Take a strip that has a water soluble ink sample on it and lower it into the water in the cup until the dot is just above the water line. Fold the top edge of the strip over the cup (or tape it in place) so that it remains upright and does not fall down into the cup. Do the same with any other samples from water soluble markers.
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Take a strip that has a permanent ink dot on it and lower it into the alcohol until the dot is just above the liquid. Fold the top edge of the strip over the cup, just as you did for the water soluble samples. Do the same for any other strips that have permanent marker samples on them.
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Wait and watch for about 15 minutes. You will observe the water and alcohol creeping up the strips very slowly. As they go up, the ink will begin "bleeding" and traveling up the strip.
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Observe the strips after the liquids have traveled all the way, or most of the way, to the top of the strips. You should see a band of colors stretching up the strip. These colors were mixed together to make the black. Black water soluble markers often contain blue, green, red or yellow dyes. The pigments that have the greatest chemical attraction to the paper will separate out first and will appear at the bottom. The pigments that have the greatest chemical attraction to the water or alcohol will separate out last and will appear at the top.
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Take the strips out and let them dry. The colors should stay intact.
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Tips & Warnings
Try "radial chromatography": put the dot in the center of a round filter and add liquid in the center, right on top of the dot. The colors should spread outward, in a circular band. This is called "radial chromatography."
Isopropyl alcohol is toxic and should not be ingested.
