噻虫胺和灭蝇胺在韭菜中的消解动态及初步膳食风险评估

Dissipation Dynamics and Preliminary Dietary Risk Assessment of Clothianidin and Cyromazine in Chinese Chives

建立了QuEChERS-液相色谱-质谱联用(LC-MS/MS)同时测定韭菜中噻虫胺和灭蝇胺残留量的分析方法,并采用该方法研究了这2种农药在韭菜中的消解动态及最终残留量。样品经乙腈提取,用N-丙基乙二胺(PSA)、C_(18)和石墨化碳(PC)净化,正离子电离,多反应监测模式,LC-MS/MS测定,外标法定量。结果表明:在0.005～1.000 mg/kg添加水平下,噻虫胺在韭菜中的平均回收率为90.0%～95.9%,相对标准偏差(RSD)为1.7%～3.3%;灭蝇胺在韭菜中的平均回收率为94.7～98.7%,RSD为0.8%～3.0%。样品中噻虫胺和灭蝇胺的定量限(LOQ)分别为0.010、0.005 mg/kg。噻虫胺和灭蝇胺在韭菜中残留量均未检出。20%噻虫胺·灭蝇胺悬浮剂按有效成分1 800 g/hm^2施药2次,施药间隔期为45 d,安全间隔期20 d,噻虫胺在韭菜中的残留量均<0.01 mg/kg,灭蝇胺在韭菜中的残留量均<0.005 mg/kg。

In this study, a simple and practical QuEChERS-based liquid chromatography-tandem mass spectrometry(LC-MS/MS) method was established to measure the residues of clothianidin and cyromazine in Chinese chives. The samples were extracted by acetonitrile and cleaned by primary secondary amine(PSA), C18 and pesticarb(PC) sorbent, and then were measured by LC-MS/MS operated in the positive electrospray ionization(ESI) mode. The data were collected in multiple reaction monitoring(MRM) mode. The results showed the average recoveries of clothianidin in Chinese chives were 90.0%~95.9% at the four spiking levels from 0.005 to 1.0 mg/kg with the relative standard deviations(RSDs) of 1.7%~3.3%. The average recoveries of cyromazine were 94.7~98.7% with the RSDs of 0.8%~3.0%. The limits of quantitation(LOQs) of clothianidin and cyromazine were 0.01 mg/kg and 0.005 mg/kg,respectively. The dissipation dynamic study showed that clothianidin and cyromazine in Chinese chives were not detected out. When 20% clothianidin-cyromazine SC was applied for 2 times at an interval of 45 days with the dose of 1 800 g/hm^2, the residue of clothianidin was less than 0.01 mg/kg and that of cyromazine was below 0.005 mg/kg on the 20 th day after the last spray.