甲草胺在水稻上的残留及消解动态

采用气相色谱电子捕获检测(GC-ECD)建立了水稻中除草剂甲草胺的残留分析方法。样品经乙酸乙酯提取,乙二氨基-N-丙基硅烷(PSA)和石墨化炭黑(GCB)净化后采用GC-ECD检测。结果表明:在0.01~1mg/L范围内甲草胺浓度与响应值线性关系良好,相关系数(r)为0.998 8。当甲草胺在水稻植株、稻壳、糙米、田水和土壤中的添加水平为0.01~0.5mg/kg时,平均回收率为79.5%~113.6%,相对标准偏差(RSD)为2.5%~12.7%。甲草胺的最低检出浓度为0.01mg/kg。采用该方法对甲草胺在田间水稻中的消解动态和最终残留进行了测定。甲草胺在稻田植株和田水样品中的消解均符合一级动力学方程。半衰期分别为11.17~26.65d和1.56~1.78d,属于易降解农药。

Residue and degradation dynamics of alachlor in rice

A residue analytical method of alachlor in paddy was established by using gas chromatography equipped with an electron-capture detector (GC-ECD). The samples were extracted with ethyl acetate, purified with primary secondary amine (PSA) and graphitized carbon black (GCB), and analyzed by GC-ECD.The method revealed excellent linearity (r=0.998 8) for alachlor in the range of 0.01-1 mg/L.The recoveries ranged from 79.5% to 113.6% for the target compound at three spiking levels from 0.01 to 0.5 mg/kg with relative standard deviations (RSD) of 2.5%-12.7% in all matrices. The limit of detection (LOD) was 0.01 mg/kg. The decline study of alachlor residue in rice plants and paddy water showed that the decline curves accorded with the first-order kinetics equation, and the half-life of alachlor was 11.17-26.65 d in rice plants and 1.56-1.78 d in paddy water, respectively. Alachlor is an easily degradable pesticide.