Chromatography

What is chromatography?

Black ink looks as if it is just one color. In fact, it is a mixture of different colors. You can separate out the different colors using a technique called chromatography.

Special paper, rather like filter paper or blotting paper, is used.

In the above diagram a small drop of ink has been placed on the paper. The water in the beaker has soaked up into the paper. As the water moves up the paper, the colors in the ink separate out.

The resulting paper is called a chromatography.

The colors separate because the water dissolves the ink. As the water moves up the paper, it carries the particles of ink with it. Different kinds of ink particles are carried different distances before they get left behind on the paper.

Some ink does not dissolve in water-for example, the ink in a permanent marker pen. To separate the colors you have to use a liquid that the colors do dissolve in-for example, alcohol.

Using Chromatography

Chromatography is used to study the dyes used in food. Some food dyes contain only one substance. Others contain a mixture of different colored substances.