壬菌铜和吡唑醚菌酯在苹果和土壤中的残留及消解动态

建立了同时测定苹果及其土壤中壬菌铜和吡唑醚菌酯残留的分散固相萃取-高效液相色谱-串联质谱（DSPE-HPLC-MS/MS）方法，并采用该方法研究了24%吡唑醚菌酯·壬菌铜微乳剂在苹果和土壤中的残留及消解动态。其中壬菌铜以硫化钠为破络剂，将其转化为壬基酚磺酸后进行检测。样品用乙腈提取，同时加入硫化钠，经N-丙基乙二胺（PSA）净化后，采用C₁₈色谱柱，以甲醇-水为流动相梯度洗脱分离，于多反应监测模式下经正负离子同时扫描进行定性，基质匹配标准曲线外标法定量。结果表明:在0.1~10 mg/kg添加水平下，壬菌铜在苹果及土壤中的回收率范围为92%~103%，相对标准偏差（RSD）为1.3%~5.1%；在0.01~1 mg/kg添加水平下，吡唑醚菌酯在苹果及土壤中的回收率范围为96%~105%，RSD为2.4%~4.6%。苹果及土壤中壬菌铜和吡唑醚菌酯的最低检测浓度（LOQ）分别为0.1和0.01 mg/kg。2014-2015年，中国宁夏、北京和山东两年三地的田间残留试验表明:壬菌铜在苹果和土壤中的消解半衰期分别为2.7~5.4和2.0~5.8 d，吡唑醚菌酯在苹果和土壤中的消解半衰期分别为4.3~8.3和3.6~10.2 d；采用24%吡唑醚菌酯·壬菌铜微乳剂，分别按推荐剂量（有效成分300 mg/kg）和推荐剂量的1.5倍（有效成分450 mg/kg）于苹果幼果期施药，最多施药4次，距末次施药14 d时，壬菌铜在苹果中的最大残留量为0.31 mg/kg，远低于日本规定的最大允许残留限量（MRL）值（5 mg/kg），吡唑醚菌酯在苹果中的最大残留量为0.27 mg/kg，低于中国规定的MRL值（0.5 mg/kg）。

Determination and dissipation dynamics of cuppric nonyl phenolsulfonate and pyraclostrobin in apples and soil

A rapid analytical method for simultaneous determination of cuppric nonyl phenolsulfonate and pyraclostrobin in apples and soil was developed using dispersive solid phase extraction and high performance liquid chromatography-tandem mass spectrometry (DSPE-HPLC-MS/MS). Residues and dissipation of cuppric nonyl phenolsulfonate and pyraclostrobin in apples and soil were investigated. Cuppric nonyl phenolsulfonate was transformed into nonyl phenol sulfonic acid by using sodium sulfide as the complex-breaking agent. Samples were extracted by acetonitrile with the addition of sodium sulfide and then cleaned up by primary secondary amine(PSA), followed by separation on a reversed phase C₁₈ column using methol-water as mobile phase with a gradient elution program. Qualitative and quantitative analyses were performed with electrospray ionization in both negative and positive ion modes under multiple reaction monitoring (MRM) mode. The results showed that the recoveries of cuppric nonyl phenolsulfonate at the spiked level of 0.1-10 mg/kg in apple and soil samples were in the range of 92%~103%, with relative standard deviation of 1.3%-5.1%; the recoveries of pyraclostrobin at spiked level of 0.01-1 mg/kg in apple and soil samples were in the range of 96%-105%, with relative standard deviation of 2.4%-4.6%; the limits of quantification (LOQs) of cuppric nonyl phenolsulfonate and pyraclostrobin in apple and soil samples were 0.1mg/kg and 0.01 mg/kg, respectively. Field experiments carried out in Ningxia, Shandong and Beijing during 2014-2015 showed that the half-lives of cuppric nonyl phenolsulfonate were 2.7-5.4 d in apples and 2.0-5.8 d in soil, and half-lives of pyraclostrobin were 4.3-8.3 d in apples and 3.6-10.2 d in soil. When the recommended dosage and 1.5 times of the recommended dosage (300 mg/kg and 450 mg/kg) of cuppric nonyl phenolsulfonate and pyraclostrobin (21% ME) were sprayed for 3-4 times at the young fruit period, the maximum residual concentration of cuppric nonyl phenolsulfonate and pyraclostrobin in apples with an harvest interval of 14 days was 0.31mg/kg and 0.27 mg/kg respectively, which were below the maximum residue limits (MRL) in apples for cuppric nonyl phenolsulfonate defined by Japan (5 mg/kg) and the MRL for pyraclostrobin in apple defined by China (0.5 mg/kg).