Chromatography

Chromatography of many kinds is widely used throughout the chemical industry. Environmental testing laboratories look for trace quantities of contaminants such as PCBs in waste oil, and pesticides such as DDT in groundwater. The Environmental Protection Agency uses chromatography to test drinking water and to monitor air quality. Pharmaceutical companies use chromatography both to prepare large quantities of extremely pure materials, and also to analyze the purified compounds for trace contaminants.

A growing use of chromatography in the pharmaceutical industry is for the separation of chiral compounds. These compounds have molecules that differ slightly in the way their atoms are oriented in space. Although identical in almost every other way, including molecular weight, element composition, and physical properties, the two different forms—called optical isomers, or enantiomers—can have enormous differences in their biological activity. The compound thalidomide, for example, has two optical isomers. One causes birth defects when women take it early in pregnancy; the other isomer does not. Because this compound looks promising for the treatment of certain drug-resistant illnesses, it is important that the benign form be separated completely from the dangerous isomer.

Chromatography is used for quality control in the food industry, by separating and analyzing additives, vitamins, preservatives, proteins, and amino acids. It can also separate and detect contaminants such as aflatoxin, a cancer-causing chemical produced by a mold on peanuts. Chromatography can be used for purposes as varied as finding drug compounds in urine or other body fluids, to looking for traces of flammable chemicals in burned material from possible arson sites.