二氰蒽醌和吡唑醚菌酯在苹果中的残留及消解动态

Residue and dissipation dynamics of dithianon and pyraclostrobin in apples

建立了超高效液相色谱-二极管阵列检测器检测二氰蒽醌和吡唑醚菌酯在苹果中残留量的分析方法,并对2种农药在苹果中的消解动态及最终残留量进行了研究。结果表明：在0.1～5 mg/kg添加水平下,二氰蒽醌和吡唑醚菌酯在苹果中的平均回收率为72%～98%,相对标准偏差为2.0%～9.7%;2种农药在苹果中的定量限均为0.1 mg/kg。二氰蒽醌和吡唑醚菌酯在苹果中的消解半衰期分别为3.0～6.5 d和13.5～23.6 d。采用16%唑醚·氰蒽醌水分散粒剂对水施药有效成分质量浓度为0.43和0.64 g/L,分别施药3～4次,距最后一次施药21 d时,苹果中二氰蒽醌残留量为〈0.1～0.80 mg/kg,吡唑醚菌酯残留量为〈0.10～0.34 mg/kg,均低于中国国家标准中规定的苹果中二氰蒽醌和吡唑醚菌酯最大残留限量值5.0 mg/kg和0.5 mg/kg。建议采用16%唑醚·氰蒽醌水分散粒剂在苹果上的最大施药剂量为有效成分质量浓度0.43 g/L,施药间隔期7 d,最多施药3次,安全间隔期为21 d。

A rapid analytical method for simultaneous determination of dithianon and pyraclostrobin in apple samples was developed using ultra high liquid chromatography with photo-diode array. Residues and dissipation of dithianon and pyraclostrobin in apples were investigated. At the fortified level from 0.1 mg/kg to 5 mg/kg, the recoveries of dithianon and pyraclostrobin ranged from 72% to 98% with the relative standard deviations varied from 2.0 % to 9.7 %. The limit of quantification（LOQ） of this method was 0.1 mg/kg. The half-lives of dithianon and pyraclostrobin in apples were 3.0-6.5 d and 13.5-23.6 d,respectively. When the recommended dosage（0.43 g a.i./L） and 1.5 times of the recommended dosage（0.64 g a.i./L） of 16% pyraclostrobin·dithianon were sprayed for 3-4 times, the terminal residues of dithianon and pyraclostrobin at the 21 th day after the last application ranged from 0.1 mg/kg to 0.80 mg/kg and from 0.1 mg/kg to 0.34 mg/kg, respectively, which were below the maximum residue limits of dithianon（5.0 mg/kg） and pyraclostrobin（0.5 mg/kg） in apples. It is recommendated that, for the prevention of anthrax of apples, the security interval of 16% pyraclostrobin·dithianon water dispersible granules is 21 days, when sprayed for 3 times at the dose of 0.43 a.i.g/L.