HPLC-UV residue analytical method for monosulfuron [N-[( 4' -methyl) pyrimidin- 2' -yl]-2-nitrophenylsulfonyl urea] in soil and wheat was developed. Monosulfuron residues were recovered by solvent extract...HPLC-UV residue analytical method for monosulfuron [N-[( 4' -methyl) pyrimidin- 2' -yl]-2-nitrophenylsulfonyl urea] in soil and wheat was developed. Monosulfuron residues were recovered by solvent extraction, followed by liquid-liquid partition, and C 18 cartrige clean-up. Excellent method recoveries ranging from 95%—104% for both fortified soil and wheat grain were obtained with coefficients of variation 1.5%—11.8%. The minimum detectable quantities in soil and wheat were both 4 ng, the limit of detection was 0.02 mg/kg. When monosulfuron was applied according to double dosage of maximum recommended use direction(120 g ai/hm 2 of 10% monosulfuron wettable powder sprayed for once during development of wheat) in field studies conducted in Shandong Province and near Beijing, monosulfuron residues was not detected in soil and wheat samples collected 75 d after application. Laboratory soil degradation studies showed that monosulfuron degraded faster in acidic soil and strong alkaline soil than in neutral or weak alkaline soil. Half lives in Jiangxi soil, Shijiazhuang soil, Jiangsu soil and Heilongjiang soil were 41, 48, 87 and 84 d respectively. Monosulfuron residues dissipated rapidly in Shandong and Beijing field test sites with half-lives of less than 14 d.展开更多
Fourteen new derivatives of avermectin B_(1a) and ivermectin B_(1a) were synthesized from C_5-O-triphenylsilyl avermectin B_(1a) and ivermectin B_(1a)(yield from 40% to 83%). Their chemical structures were characteriz...Fourteen new derivatives of avermectin B_(1a) and ivermectin B_(1a) were synthesized from C_5-O-triphenylsilyl avermectin B_(1a) and ivermectin B_(1a)(yield from 40% to 83%). Their chemical structures were characterized by means of IR, ()~1H NMR, ()^(13)C NMR and FAB-MS spectrometries. Some of them show excellent insecticidal activity.展开更多
文摘HPLC-UV residue analytical method for monosulfuron [N-[( 4' -methyl) pyrimidin- 2' -yl]-2-nitrophenylsulfonyl urea] in soil and wheat was developed. Monosulfuron residues were recovered by solvent extraction, followed by liquid-liquid partition, and C 18 cartrige clean-up. Excellent method recoveries ranging from 95%—104% for both fortified soil and wheat grain were obtained with coefficients of variation 1.5%—11.8%. The minimum detectable quantities in soil and wheat were both 4 ng, the limit of detection was 0.02 mg/kg. When monosulfuron was applied according to double dosage of maximum recommended use direction(120 g ai/hm 2 of 10% monosulfuron wettable powder sprayed for once during development of wheat) in field studies conducted in Shandong Province and near Beijing, monosulfuron residues was not detected in soil and wheat samples collected 75 d after application. Laboratory soil degradation studies showed that monosulfuron degraded faster in acidic soil and strong alkaline soil than in neutral or weak alkaline soil. Half lives in Jiangxi soil, Shijiazhuang soil, Jiangsu soil and Heilongjiang soil were 41, 48, 87 and 84 d respectively. Monosulfuron residues dissipated rapidly in Shandong and Beijing field test sites with half-lives of less than 14 d.
文摘Fourteen new derivatives of avermectin B_(1a) and ivermectin B_(1a) were synthesized from C_5-O-triphenylsilyl avermectin B_(1a) and ivermectin B_(1a)(yield from 40% to 83%). Their chemical structures were characterized by means of IR, ()~1H NMR, ()^(13)C NMR and FAB-MS spectrometries. Some of them show excellent insecticidal activity.
