The decline and residues of hexaconazole in tomato and soil.

The decline and terminal residues of hexaconazole in tomato and soil in open field were studied. Hexaconazole residues were determined by gas chromatography coupled with an electron capture detector. Recoveries were between 89% and 110% with RSD of 2.99-5.88% in tomato and 90-119% with RSD of 1.15-5.76% in soil at spiked levels of 0.01, 0.1, and 1 mg/kg, respectively. The limit of detection of hexaconazole was 6.3 × 10(-12) g. The decline rates of hexaconazole were described using first-order kinetics and the mean half-lives of hexaconazole in tomato and soil were 4.3 and 18.1 days, respectively. The terminal residues in tomato at interval of 7 days at the dosage of 150 g.a.i./hm(2) for three or four times were all below 0.1 mg/kg. This work would be the guidance of establishing the maximum residue limit of hexaconazole in tomato in China.