The metabolism of dimethoate and its N-butyl homologues in tomato plants has been studied by use of 32P and 35S labelled initial products. The preparation of thiol-35S-labelled dimethoate is described. Formation and break down of dimethoxon and N-tert.-butyl-dimethoxon have been measured by radio-thin layer chromatography. The calculated biological half times have been compared with those in aqueous buffer solutions; remarkable differences between dimethoate and dimethoxon derivatives have been

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... observed. The extension of the N-alkyl chain causes a more rapid biological breakdown. The technique described is also useful for the comparison of other organophosphorus compounds (OPC).