FRACTIONATION OF [C-14] METOLACHLOR METABOLITES BY CENTRIFUGAL PARTITION CHROMATOGRAPHY

Metolachlor ethylphenyl)-N-(2-methoxy-1-methylethyl)acetamide) is one of the most widely used and important herbicides throughout the world. In order to understand the biodegradation pathways for this compound it is essential to develop large scale separation and purification pro cedures for its metabolites. However, analyzing crude plant extracts f or these compounds poses several problems. In particular, the complex matrix and low levels of many metabolites requires a preparative separ ation and detection procedure that is both sensitive and robust. The u se of [C-14] labeled compounds and scintillation counting satisfies th e sensitivity requirement but creates an additional problem when using preparative LC. Irreversible adsorption to the stationary phase frequ ently occurs when analyzing ''real-world'' biological samples or extra cts thereof. This is particularly undesirable if the matrix contains r adioactive components. This problem can be avoided by using a techniqu e with a liquid stationary phase such as centrifugal partition chromat ography (CPC). CPC is used for the preparative fractionation of [C-14] metolachlor metabolites contained in crude corn plant extract. Also, a rapid analytical HPLC method is developed for the separation of stand ard non-radiolabeled metolachlor metabolites on a dimethylphenyl-deriv atized beta-cyclodextrin stationary phase.