氯氟吡氧乙酸在小麦和土壤中的检测方法及其残留动态

RESIDUE DETECTION AND DEGRADATION OF FLUROXYPYR IN WHEAT AND SOIL

为了解氯氟吡氧乙酸在小麦和土壤中的消解动态及其残留状况,建立了氯氟吡氧乙酸在小麦和土壤中的液相色谱分析方法,并在天津、山东和江苏三地开展了氯氟吡氧乙酸在小麦和土壤中残留田间试验研究.结果表明,采用乙酸乙酯和10%H3PO4(含4%KC l)振荡提取小麦和土壤中的氯氟吡氧乙酸,氯仿萃取,弗罗里硅土固相萃取柱净化,乙醚/石油醚(体积比为3∶97)混合液洗脱,减压浓缩,N2吹干,乙腈定容,液相色谱仪带二极管阵列检测器(DAD)进行测定,小麦植株、籽粒和土壤中氯氟吡氧乙酸的添加回收率分别为91.3%—100.2%、82.0%—90.9%和81.0%—99.7%,变异系数分别为3.2%—8.7%、3.1%—9.6%和3.1%—5.3%;氯氟吡氧乙酸在小麦和土壤中的最小检出量为3.57×10-10g,最低检出浓度为0.005 m.gkg-1.在小麦苗期喷雾施用19%苯磺隆.氯氟吡氧乙酸可湿性粉剂,氯氟吡氧乙酸在小麦植株和土壤中的残留消解动态规律符合方程Ct=C0e-kt,消解半衰期分别为7.22—9.65 d和7.99—9.92 d.在小麦芽后茎叶期喷雾施用19%苯磺隆.氯氟吡氧乙酸可湿性粉剂1次,其制剂施用量为0.06—0.09.gm-2,在小麦收获时,氯氟吡氧乙酸在小麦籽粒中的残留量均低于方法最低检出浓度.表明按推荐剂量和1.5倍在小麦芽后茎叶期喷雾施用19%苯磺隆.氯氟吡氧乙酸可湿性粉剂1次,氯氟吡氧乙酸在小麦籽粒上的残留是安全的.

In order to understand clearly residue pollution and degradation trends of fluroxypyr in wheat and soil,an analytical method of liquid chromatography was established for determining fluroxypyr residue in wheat and soil,and the residue and degradation of fluroxypyr were also investigated.Fluroxypyr residue was extracted first with ethyl acetate and 2 mL 10%H3PO4（including 4%KCl） then with chloroform,purified using Florisil soild phase extraction,and determined by HPLC equipped with a DAD detector.The experimental results showed that the average recovery of fluroxypyr stood in a range of 81%—100.2% at five spiking levels from 0.05 mg·kg-1 to 1 mg·kg-1 with relative standard deviations of 3.1%—9.6% in wheat and soil.Limit of detection was 3.57×10-10g and the lowest concentration detected was 0.005 mg·kg-1 in wheat and soil.An control and contrast trial experiments were carried out in Tianjin,Shandong province and Jiangsu province.The degradation of fluroxypyr in wheat and soil could be described with an equation Ct=C0e-kt.The half-life of fluroxypyr was 7.22—9.65 d and 7.99—9.92 d in wheat and soli,respectively.When 19% tribenuron-methly and fluroxypyr wettable power was applied once with dosages of 0.06—0.09 g·m-2 in the seedling stage,the final residues of the fluroxypyr were below the lowest detectable concentration（0.005 mg·kg-1） in wheat.