May 14, 2010

Happy Birthday, Mikhail Tsvett

This Russian botanist (plant scientist), born on this day in 1872, discovered chromatography. He was trying to separate a mixture of plant pigments that were very similar to each other. One method he tried was trickling the mixture through a glass tube packed with calcium carbonate powder. As the liquid trickled down through the powder, each kind of pigment stuck to the powder with its own unique amount of strength. This created a series of bands (or stripes), and each band was a different pigment.
Using his new technique, Tsvett discovered several new plant pigments. He named the technique chromatography, the resulting bands a chromatograph, and the new pigments carotenoids.
Although Western scientists did not discover Tsvett's work for 30 years, his technique is now used all over the world.

Felt Pen Chromatography

This will work with any water-based felt-tipped pen, but it's most fun to use a bunch of different brands of black markers. (Again, remember, they have to be water-based markers! Don'
Another felt pen chromatography experiment, using blotter paper, is described on the website Dad Can Do. Yes Mag also writes up the experiment (with slightly different instructions—but lots of photos!)

Chalk Chromatography

Test red, yellow, green and blue food coloring to see if they are made of various substances. Instead of using coffee filters or blotter paper, use white chalk. At the end of the experiment, you will have cool-looking chalk with a colorful outer decoration.

Get instructions here.

Leaf Chromatography

Squeeze some “leaf juice” onto the coffee filter to test for pigments in plant leaves. This experiment is more like Tsvett's original research. Get instructions here.

T-Shirt Chromatography
Get an old (or cheap-and-new) white T-shirt for this activity. This time, use alcohol rather than water, and permanent markers rather than water-based ones. Follow the instructions carefully to make a unique Tee to wear.

Did You Know...?

Forensic science (crime-scene investigation) can involve chromatography to see what type of pen was used in a crucial piece of evidence. Unfortunately, the test would tend to destroy the evidence—so I'm sure that CSI scientists test only part of a small part of the message, letter, or other ink sample.