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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 chromatographic method for the determination of azoxystrobin in soybean was established and its digestion dynamics and final residues in plant and soybean seeds were studied. The samples were extracted with acetonitrile and purified with Florisil glass, and determined by gas chromatography-electron capture detector (GC-ECD). The results showed that the average recoveries of azoxystrobin were 93.4% ~ 101.1% and the relative standard deviations (RSDs) were 1.2% ~ 7.5% at the three levels of 0.025,0.25,2.0 mg / kg. The minimum detectable amount 1 × 10-12 g, the lowest detection concentration of 0.025 mg / kg. The half-life of azoxystrobin in soybean plants ranged from 0.8 to 3.6 days at a dose of 1.5 times the recommended dose (active ingredient 337.5 g / hm2). The application of 225,337.5 g / hm2 for 3 to 4 times showed that the residual amount of azoxystrobin in the harvesting period was lower than the MRL of 0.5 mg / kg as stipulated by the International Codex Alimentarius Commission (CAC) . According to the recommended dosage of 225 g / hm2, it is suggested that the MRL value of azoxystrobin in soybean should be tentatively set at 0.5 mg / kg, the safety interval should be 14 days, and the application times should not exceed 3 times.