戊唑醇在葡萄和土壤中的残留和消解动态

建立了葡萄中戊唑醇残留的气相色谱测定方法,并研究了其在葡萄和土壤中的消解动态。土壤用乙腈提取,无需净化,葡萄样品用甲醇提取,二氯甲烷液液分配净化后用气相色谱-氮磷检测器(GC-NPD)测定。结果表明:在 0.01、0.1、1 mg/kg 3个添加水平下,戊唑醇的平均回收率为85.0%~98.8%,相对标准偏差(RSD)为2.9%~10.4%;最小检出量为1×10-11g,最低检测浓度为0.01 mg/kg。采用250 g/L戊唑醇水乳剂按有效成分187.5 mg/L剂量(推荐剂量的1.5倍)施药,戊唑醇在葡萄中的半衰期为9.8~12.2 d,在土壤中的半衰期为8.2~17.3 d,药后28、35 d葡萄中的最终残留量≤0.81 mg/kg,低于国际食品法典委员会(CAC)和中国规定的最大残留限量2.0 mg/kg。建议在葡萄上使用250 g/L戊唑醇水乳剂时,施药剂量最高为有效成分187.5 mg/L,施药2~3次,采收间隔期为28 d。

Study on residues and dissipation of tebuconazole in grapes and soil

A gas chromatography method was developed for determining tebuconazole residues in grapes and soil.The samples were extracted with acetonitrile or methanol, cleaned up by methylene dichloride and determined by gas chromatograph with Nitrogen Phosphorus Detector (GC-NPD).Results showed that at fortified levels of 0.01 to 1 mg/kg,the ranges of average recoveries and relative standard deviations of the method were 85.0% to 98.8%,2.9% to 10.4% respectively.The limit of detection was estimated to be 1×10^-11 g,and the limit of quantification was 0.01 mg/kg.Sprayed with high dosage of 187.5 mg(a.i)/L,the half-life of tebuconazole was 9.8 to 12.2 days in grapes and 8.2 to 17.3 days in soil.Terminal residues in grapes were less 0.81 mg/kg after 28 and 35 days,below the MRL of CAC and China(2.0 mg/kg).Recommended dosage of 187.5 mg(a.i)/L for tebuconazole 250 g/L EW was suggested to apply in grapes with preharvest interval at 28 days and maximum application below three times.