What is chromatography and what is it used for?
(Lansing State Journal, September 22,1993)


Chromatography refers to a set of techniques used to separate different compounds.  The word comes from the Greek chromatos (color) and graphein (to write).  So, as one might guess, chromatography involves separating chemicals and identifying them by color.

Chromatography has many uses.  It is commonly used in laboratories to isolate new compounds, analyze subtle differences between different environmental samples, and even in the sequencing of DNA.

To perform chromatography, one needs two things a matrix and a color indicator.  A matrix is simply the material to which a sample is applied.  the material is often porous, acting as a filter that affects the rate of flow of a sample.  Special beads with different pore sizes are commonly used to separate proteins in biochemistry labs.

The matrix may interact with a sample, and depending on the chemical properties of both, affect its flow.  Paper is one such matrix, and is commonly used to analyze mixtures of sugars.

The color indicator may be the compound itself.  Some organic compounds are bright yellow or orange, which makes them easy to identify on a chromatogram.  Others need to react with other chemicals to become colored.  Dyes specific for particular chemical properties can be used to identify samples.  For example, rhodamine dye can be applied to visualize fats and oils.

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