CHROMATOGRAPH

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References: 9

This uses a group of methods for separating a mixture of substances into their component parts. Chromatography is a misnomer for the techniques since the colour of the components is not really used for identifying substances in modern techniques. There are four basic types of chromatograph using one phase or substrate which may be liquid or solid through which the test substance (gas or liquid) moves. A common feature of these methods is that the difference in rate of movement of the components of the test sample (plus reagents) is used to identify the separate components.

In the clinical laboratory these methods are used to detect complex substances such as drugs and hormones. Examples of chromatographs are the gas-liquid chromatograph (GLC) and the thin layer chromatograph (TLC). Both these are being superseded by high-performance liquid chromatography (HPLC), although some compounds can only be measured by GLC.