Gas-liquid chromatographic determination of pentachlorophenol in milk

A gas-liquid chromatographic (GLC) method developed by other workers for determining pentachlorophenol (PCP) in water has been adapted for determining PCP in raw and homogenized milk. PCP is extracted from milk with benzene and from the benzene into a potassium carbonate solution. Acetic anhydride is added to the aqueous solution to form PCP acetate, which is extracted into hexane and then determined by electron capture GLC. Duplicate determinations of PCP in milk fortified at levels of 0.02, 0.2, and 2.0 ppm gave respective average recoveries of 80.0, 87.2, and 85.0%. PCP levels as low as 0.005 ppm can be detected in 20 g milk.