采用液相色谱-串联质谱法( LC-MS/MS)研究了白菜中涕灭威及其代谢物的残留动态行为.按农民常用施药量(3 000 g/hm2)将涕灭威沟施予田地后,定期取样检测,并建立其残留行为的数学模型.结果表明,用 LC-MS/MS 测定涕灭威及其代谢物,在0. 005~0. 2 mg/L范围内线性关系良好,平均回收率为78. 9%~108. 5%,相对标准偏差为2. 03%~8. 91%( n=8).涕灭威在白菜中的浓度升高和降低的过程均符合一级动力学模型( c=0. 020e0. 136t和c=0. 65e-0. 059t ),相关系数( r2 )分别为0. 888和0. 979,半衰期为29. 1天.代谢产物涕灭威砜和涕灭威亚砜在白菜中的浓度降低时同样符合一级动力学方程( c=23. 4e-0. 044t和 c=4. 54e-0. 027t ),r2 分别为 0. 916 和 0. 972.涕灭威、涕灭威砜和涕灭威亚砜在白菜中的含量要降到国内外限量要求 0. 01 mg/kg,分别需要 70. 7、226. 6 和 176. 3 天.白菜生长周期为120天,收获时涕灭威砜和涕灭威亚砜含量仍超过国内外限量要求.因此,在本文施药量下,涕灭威不能使用.该数据为涕灭威的安全使用和农药残留动态行为研究提供了理论依据.
A liquid chromatography-tandem mass spectrometry ( LC-MS/MS ) method was developed for the study of dynamic behavior of aldicarb and its metabolite residues in cabbage. Aldicarb was applied onto cultivated cabbages. The pesticides concentrations were measured periodically(between application and harvest),and modeled to illustrate the dynamic behav-ior. The results showed that the liner ranges of aldicarb and its metabolites were from 0. 005 to 0. 2 mg/L,and the recoveries ranged from 78. 9% to 108. 5% with the relative standard devia-tions of 2. 03%-8. 91%( n=8 ). The aldicarb in cabbage increased at first with the first-order kinetic equation model of c=0. 020e0.136t with the correlation coefficient(r2)of 0. 888,and then decreased with the equation of c=0. 65e-0. 059t with the r2 of 0. 979 and the half-life of 29. 1 d. The reducing processes of aldicarb-sulfone and aldicarb-sulfoxide both matched the first-order kinetic equations(c=23. 4e-0.044t and c=4. 54e-0.027t)with r2 of 0. 916 and 0. 972 respectively. To meet the limitation requirement of 0. 01 mg/kg,70. 7,226. 6 and 176. 3 d were respectively nec-essary for aldicarb,aldicarb-sulfone and aldicarb-sulfoxide. Final residues of aldicarb-sulfone and aldicarb-sulfoxide were still more than the limitation requirements,indicating that aldicarb should not be used in vegetables of growth cycle shorter than 120 d. This study provided theoretical basis for dynamic behavior of aldicarb residue and its safe use in vegetables.
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