The application of the thin-layer chromatographic-enzyme inhibition technique to organochlorine insecticides

Abstract

The application of the thin-layer chromatographic-enzymatic technique to lindane, pp′-DDT, methoxychlor, heptachlor, aldrin, dieldrin and endrin has been investigated. By use of this technique, lindane in amounts of 500 ng or more is detected, whereas the other pesticides tested remain undetected up to 10 µg. Positive results for the tests for organophosphorus and carbamate pesticides with the thin-layer chromatographic-enzymatic technique therefore require corroboration from other tests to exclude the possibility of the presence of lindane. Kinetic enzymatic studies have shown that lindane is a non-competitive inhibitor of carboxylesterase, the predominant enzyme of liver homogenate, which is responsible for the hydrolysis of a chromogenic substrate. Lindane does not inhibit the cholinesterase in liver homogenate.