固相萃取-液相色谱-串联质谱法测定蔬菜中4种有机磷农药及其代谢产物

在蔬菜种植中经常使用的有机磷农药马拉硫磷、甲基对硫磷、敌百虫及乙酰甲胺磷可能转化的主要代谢产物分别为O，O-二甲基二硫代磷酸酯、对硝基酚、敌敌畏及甲胺磷。根据蔬菜色素等基质的含量不同采用不同的净化方法，色素含量高的蔬菜采用活性炭和弗罗里硅土串联固相萃取小柱净化，其他蔬菜采用弗罗里硅土固相萃取小柱净化。色谱分离选择ACQUITY UPLC BEH HILIC色谱柱，以乙腈和5 mmol/L乙酸铵水溶液为流动相进行梯度洗脱，得到的分离效果较好；质谱采用电喷雾正或负离子电离、多反应监测模式检测。液相色谱-质谱检测的基质效应为15.3%~45.1%；4种有机磷农药及其代谢物的方法回收率为76.9%~102.8%，相对标准偏差为5.92%~10.19%；定量限范围为0.001~0.01 mg/L；在0.01~1.00 mg/L范围内线性相关系数为0.9982~0.9999。方法具有良好的回收率、相对标准偏差、定量限及线性关系，适合蔬菜中有机磷及代谢物的检测，应用该检测方法对农贸市场购买的白菜、辣椒、西红柿及洋葱进行了检测。

Determination of four organophosphorus pesticides and their metabolites in vegetables using solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry

Organophosphorus pesticides (OPs), malathion, methyl parathion, trichlorfon, and acephate were used frequently in vegetable cultivation, mainly metabolized into O,O-dimethyl dithiophosphate, 4-nitrophenol, dimethyl dichloroviny phosphate (DDVP) and methamidophos, respectively. A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of the organophosphorus pesticides and their metabolites. According to the difference of coloring matter contents in vegetable matrix, the pre-treatment for vegetables with high coloring matter contents were performed using activated carbon coupled with a Florisil solid-phase extraction column, and others were purified by a Florisil solid-phase extraction column. A hydrophilic interaction chromatographic column (ACQUITY UPLC BEH HILIC) was used with acetonitrile-5 mmol/L ammonium acetate as mobile phases. The MS/MS detection was performed under positive or negative electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The results showed that the matrix effect of the LC-MS/MS was 15.3%-45.1%, the recoveries of the four organophosphorus pesticides and their metabolites were 76.9%-102.8%, the precision ranged from 5.92% to 10.19%, the limits of quantification ranged from 0.001 to 0.01 mg/L, and the linear correlation coefficients were 0.9982-0.9999 in the range of 0.01-1.00 mg/L. This method was applied in the analysis of Chinese cabbages, hot peppers, tomatoes and onions from markets. This method can be applied in rapid detection of the organophosphorus pesticides and their metabolites in vegetables.