苯噻草胺在稻田水及土壤中的消解动态

研究建立了稻田水和土壤中苯噻草胺残留的检测方法。稻田水经过滤后直接进高效液相色谱-串联质谱(HPLC-MS/MS)仪分析,方法的线性范围为0.1~10 μ g/L,相关系数(R2)为0.999 3,检出限(LOD)为0.03 μ g/L,定量限(LOQ)为0.1 μ g/L;当样品中苯噻草胺的添加水平为0.1~10 μ g/L时,平均回收率在98.4%~103.2%之间,相对标准偏差(RSD)在1.9%~3.4%之间。土壤经乙腈提取,硅胶固相萃取柱净化后用高效液相色谱(带二极管阵列检测器,HPLC-DAD)仪检测,方法的线性范围为0.1 ~2 mg/L,R2为0.998 5,LOD为0.006 mg/kg,LOQ为0.02 mg/kg;当样品中苯噻草胺的添加水平为0.02~1 mg/kg时,平均回收率在75.2%~86.1%之间,RSD在3.3%~7.5%之间。采用所建立方法对北京、南京两地2009年苯噻草胺在稻田水及土壤中的消解动态进行了检测。结果表明:其在稻田水及土壤中的消解动态曲线符合一级动力学方程;苯噻草胺在稻田水中消解迅速,半衰期分别为2.1 d(北京)和1.6 d(南京);其在土壤中的消解速率两地间差异较大,且比水中的慢,半衰期分别为12.3 d(北京)和3.7 d(南京)。

Residue decline study of mefenacet in paddy water and paddy soil

A method for the determination of the mefenacet residue in the paddy water and soil was established.The paddy water sample was filtrated and then analyzed by high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS).The linear range was 0.1-10 μ g/L with the linear correlation coefficient of 0.999 3.The limit of detection (LOD) was 0.03 μ g/L and the limit of quantification(LOQ) was 0.1 μ g/L.The average fortification recovery was 98.4%-103.2% with relative standard deviation(RSD) of 1.9%-3.4% when mefenacet was spiked at 0.1-10 μ g/L level in paddy water.The soil was extracted with the acetonitrile and cleaned up by the silica gel SPE column,then analyzed by high performance liquid chromatography with diode-array detector(HPLC-DAD).The linear range was 0.1-2 mg/L with the linear correlation coefficient of 0.998 5.The LOD was 0.006 mg/kg and LOQ was 0.02 mg/kg.The average recovery was 75.2%-86.1% with RSD 3.3%-7.5% when mefenacet was spiked at 0.02-1 mg/kg level in paddy soil.The method was used to detect the decline of mefenacet in the paddy water and soil in Beijing and Nanjing in 2009.The decline study of mefenacet in paddy water and soil suggested that the decline curves accorded with the first-order kinetics equation.Mefenacet declined fast in paddy water.The half-life of mefenacet in paddy water was 2.1 d(Beijing) and 1.6 d(Nanjing),respectively.The rate of decline in the paddy soil has an evident difference,and mefenacet declined slower in the paddy soil than in the paddy water.The half-life of mefenacet in paddy soil was 12.3 d(Beijing) and 3.7 d(Nanjing),respectively.