Paper Chromatography

This technique provides an easy way to separate the components of a mixture.

Autoradiography

If the mixture contains molecules that have been labeled with a radioactive isotope, these can be located by placing the chromatogram next to a sheet of X-ray film. The location of dark spots on the developed film (because of radiation emitted by the isotope) can be correlated with the position of the substances on the chromatogram.

An Example

The figure (courtesy of Dr. James A. Bassham) shows autoradiograms of the type that were essential in working out the dark reactions of photosynthesis.

The dark spots show the radioactive compounds produced

of photosynthesis by the green alga Scenedesmus. The alga was supplied with carbon dioxide labeled with 14C, a radioactive isotope of carbon. The small rectangle and circle (lower right-hand corners) mark the spots where the cell extract was applied.
Links to two other chromatographic methods
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7 January 2011