己唑醇在水稻田中的残留及消解动态

Residues and Dissipation Dynamics of Hexaconazole in Rice Field

采用气相色谱-电子捕获检测器(GC-ECD)测定了己唑醇在田水、土壤、水稻植株和糙米、稻壳样品中的消解动态及最终残留。田水样品用二氯甲烷萃取,土壤、水稻植株、糙米和稻壳样品用甲醇提取,提取液经柱层析净化、GC-ECD检测。当己唑醇在田水中的添加浓度为0.005~1.0mg/kg时,其回收率为94.38%~97.28%之间,相对标准偏差(RSD)为1.93%~2.87%,在土壤、植株、糙米和稻壳中的添加浓度为0.02~2.0mg/kg时,其平均回收率在86.20%~96.30%之间,RSD为2.25%~6.39%;己唑醇的最小检出量为2.0×10^(-11)g,在田水中的最低检测浓度为0.005mg/kg,土壤、水稻植株、糙米和稻壳中的最低检测浓度为0.02mg/kg。消解动态试验结果显示,己唑醇在水稻植株、土壤以及田水中的消解动态规律均符合一级动力学方程,其半衰期分别为4.12~7.33d,11.77~23.18d和2.89~7.17d;最终残留试验结果表明,药后45d糙米中的己唑醇最终残留量为0.085 7mg/kg,低于我国规定的最大残留限量值0.1mg/kg,建议在稻田上使用50%己唑醇可湿性粉剂时,施药剂量为75~112.5g.a.i/ha,施药2~3次,安全间隔期为45 d。

The residual dynamics and final residues of hexaconazole in paddy water,soil,plant,brown rice and rice hull samples in supervised field residue trials were determined by gas chromatography equipped with electron capture detector(GC-ECD).Paddy water samples were extracted with methylene chloride and soil,plant,brown rice and rice hull samples were extracted with methanol.The extracts were cleaned up by column chromatography and determined by GC-ECD.Under the fortified level from 0.005 to 1.0mg/L for water,the recovery ranged from94.38%to 97.28%with the relative standard deviations of 1.93%~2.87%.Under the fortified level from 0.02 to 2.0mg/kg for soil,plant,brown rice and rice hull,the recovery ranged from86.20%to 96.30%with the relative standard deviations of 2.25%~6.39%.The limit of detection(LOD) was 2.0×10^(-11)g,and the limit of quantification(LOQ) of the method was 0.005mg/L for paddy water,0.02mg/kg for soil,plant,brown rice and rice hull.The results showed that the dynamicrules were consistent with the first order kinetics equation,and that the half-life of hexaconazole was 4.12~7.33 days in plant,11.77~23.18 days in soil and 2.89~7.17 days in paddy water,respectively.The results of residue testsindicated that the finalresidues in brown rice were less 0.085 7mg/kg after 45 days,below the MRL of China(0.1mg/kg).Hexaconazole 50%WPwas recommendedto be used in rice fieldat the dosage of 75~112.5g.a.i/ha,the pre-harvest interval of 45 days and the maximum application frequency of three times.