HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF FENTHION AND ITS METABOLITES

The biotransformation of fenthion in animals and plants leads to five major metabolites: fenthion sulphoxide, fenthion sulphone, fenthion oxygen analogue (fenoxon), fenoxon sulphoxide and fenoxon sulphone. According to the FAO, the maximum residue limit for fenthion in different commodities includes the sum of the active ingredient and the above metabolites, expressed as fenthion. In this paper, a reversed-phase high-performance liquid chromatographic method is described which allows a rapid determination of fenthion and its major metabolites. A satisfactory separation was achieved with an RP-18 column and water-acetonitrile (50:50, v/v) as the mobile phase. Under these conditions the detection limits for fenthion and its major metabolites ranged from 0.005 to 0.02 ppm.