Degradation and residues of carbofuran in soil and sweet corn (Zea mays L. var. saccharata Bailey)
1990
Aran Ngampongsai
Residual levels of carbofuran and their metabolites (3-hydroxycarbofuran, 3-ketocarbofuran) were then analyzed by gas chromatography. Carbofuran could be detected in soil only at 30 and 45 days after application. The residual levels ranged from 0.523-1.276 ppm at 30 days and decreased to 0.285-0.696 ppm at 45 days. The metabolites 3-hydroxycarbofuran and 3-ketocarbofuran in soil could not be detected. In stems carbofuran and 3-hydroxycarbofuran were found and the major portions of total carbamates in the form of 3-hydroxycarbofuran ranged from 2.187-3.178 ppm at 30 days and decreased sharply to 0.140-1.487 ppm at 45 days after application. The trace of carbofuran ranging from 0.045-0.093 ppm was detected only at 30 days in stems. The trace of residual levels of carbofuran ranging from 0.020-0.123 ppm was also found in leaves at 30 days but it could not be detected at 45, 60 and 75 days after application. 3-hydroxycarbofuran could be found at the harvest time (75 days) in grains. The residual levels ranging from 0.190-0.689 ppm were above the FAO/WHO maximum residue limits of 0.1 ppm. 3-ketocarbofuran could not be detected in soil and all parts of the sweet corn plants in this experiment.
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