Dissipation kinetics and residues analysis of pendimethalin in soil and maize under field conditions

Herbicides play an important role in the production of crops, but their residues may cause numerous human/environmental problems. Dissipation kinetics of pendimethalin and residues in soil, maize straw and cobs in winter maize under field conditions were studied by gas chromatograph-electron capture detector (GC-ECD). Dissipation followed the first order kinetics and accounted by a biphasic pattern. The half-life for initial phase and later phase was 11.70 and 34.13 days for recommended and 9.19 and 46.81 days for double dose, respectively. Percent recovery from cobs, straw and soil samples varied from 76.2-88.5, 76.6-84.4, and 85.0-89.5%. The limit of quantification was 0.001 mu g/g of sample. At harvest pendimethalin residues were below detectable limit in soil, maize cobs and maize plant at both application rates (1 and 2 kg/ha). Pendimethalin is safe for use and does not appear to pose any health hazard to consumers or harm to the environment.