嘧菌酯在大豆中的残留及消解动态

Residues and decline study of azoxystrobin in soybean

建立了大豆中嘧菌酯残留的气相色谱测定方法,并研究了其在植株和大豆籽粒中的消解动态和最终残留。样品经乙腈提取,弗罗里硅土玻璃层析柱净化,通过气相色谱-电子捕获检测器(GC-ECD)测定。结果表明,在0.025、0.25、2.0 mg/kg 3个添加水平下,嘧菌酯的平均回收率为93.4%～101.1%,相对标准偏差(RSD)为1.2%～7.5%;最小检出量为1×10-12 g,最低检测浓度为0.025 mg/kg。施药剂量为推荐剂量的1.5倍(有效成分337.5 g/hm2)时,嘧菌酯在大豆植株中的半衰期为0.8～3.6 d。在225、337.5 g/hm2剂量下施药3～4次,测得收获期大豆中嘧菌酯的残留量均低于国际食品法典委员会(CAC)规定的最大残留限量(MRL)0.5 mg/kg。按照推荐剂量225 g/hm2处理,建议我国嘧菌酯在大豆上的MRL值可暂定为0.5 mg/kg,安全间隔期为14 d,施药次数不超过3次。

A gas chromatography method was developed for determining azoxystrobin residues in soybean.The samples were extracted with acetonitrile,and cleaned up by glass column chromatography with Florisil and determined by gas chromatograph with electronic capture detector（GC-ECD）.Results showed that the fortified concentration of azoxystrobin from 0.1 mg/kg to 2.0 mg/kg,the ranges of average recoveries and coefficient variation of the method were 93.4% to 101.1%,1.2% to 7.5% respectively.The limit of detection was estimated to be 1×10-12 g,and the limit of quantification was 0.025 mg/kg.With high dosage 337.5 g a.i./ha,the half-life of azoxystrobin was 0.8 to 3.6 days in the soybean plant.Soybean plant was treated for three and four times with the dosages of 225 g a.i./ha and 337.5 g a.i./ha,the results revealed that the azoxystrobin residues in soybean were all below the MRL of CAC（0.5 mg/kg）.Recommended dosage 225 g a.i./ha of azoxystrobin 25% SC was suggested to apply in soybean,the MRL of azoxystrobin in soybean may be suggested to set at 0.5 mg/kg.It＇s recommended that the preharvest interval of azoxystrobin in soybean set at 14 days,the maximum application times below three.