QuEChERS-气相色谱-串联质谱法同时测定饲草中10种农药残留

建立了同时测定饲草中敌敌畏、乙酰甲胺磷、乐果、莠去津、乙草胺、马拉硫磷、倍硫磷、毒死蜱、氯氰菊酯和溴氰菊酯10种农药残留的QuEChERS/气相色谱-串联质谱（GC-MS/MS）方法。样品经饱和氯化钠溶液浸泡10~15 min、乙腈匀浆提取1 min，上清液以无水MgSO₄、N-丙基乙二胺（PSA）、C₁₈和石墨化碳黑（GCB）（质量比30:10:10:1）为吸附剂进行基质分散萃取净化，浓缩后用乙酸乙酯定容，通过HB-5MS气相色谱柱（30 m×250 μm，0.25 μm）分离，采用串联质谱在多反应监测模式（MRM）下检测分析。结果表明:在1~200 μg/L范围内，10种农药的进样质量浓度与其对应的峰面积间呈良好的线性关系，相关系数均大于0.99，该方法检出限（LOD）为0.001 5~0.015，定量限（LOQ）为0.005~0.05 mg/kg。在0.05、0.2和1.0 mg/kg 3个添加水平下，10种农药在饲草中的平均回收率为75%~110%，相对标准偏差（RSD）为1.7%~11.6%。利用该方法对山东省100批次饲草产品中的农药残留进行检测，共检出8种农药，其中毒死蜱的检出率较高，其在青贮料和干草料中的残留量分别在0.002~0.447和0.002~3.502 mg/kg之间，其他农药的检出率则较低，在0.027~0.428 mg/kg之间。参照国内外最大允许残留限量（MRL）值，毒死蜱、乐果、乙草胺、马拉硫磷、氯氰菊酯和溴氰菊酯在饲草中的残留水平是安全的；而莠去津和倍硫磷尚未规定其在饲草中的MRL值。该方法简单、快速、灵敏、准确，能够满足大批量饲草中农药残留的检测需要。

Simultaneous determination of ten pesticide residues in forage grass using QuEChERS-gas chromatography-tandem mass spectrometry

A multi-residue determination method was developed for the simultaneous detection of 10 pesticide (dichlorvos, acephate, dimethoate, atrazine, acetochlor, malathion, fenthion, chlorpyrifos, cypermethrin, deltamethrin) residues in forage grass, using QuEChERS method and gas chromatography-tandem mass spectrometry (GC-MS/MS). The homogenized sample was dispersed by sodium chloride solution. Then the analytes were extracted with acetonitrile. Dispersive solid phase exaction (DSPE) was carried out for the analytes purification, using anhydrous magnesium sulfate, primary secondary amine (PSA), C₁₈ and graphitized carbon black (GCB). Ethyl acetate was used as solvent substitution after solvent evaporation under nitrogen. The 10 pesticide residues were then analyzed by GC-MS/MS using capillary column HB-5MS (30 m×250 μm, 0.25 μm) and multiple reaction monitoring (MRM). All the correlation coefficients of calibration curves were over 0.99 in the linear concentration ranged from 1 to 200 μg/L. The limits of detection (LODs) were 0.001 5-0.015 mg/kg and the limits of quantitation (LOQs) were 0.005-0.05 mg/kg. The average recoveries of the 10 pesticides at 3 spiked concentration level, 0.05, 0.2 and 1.0 mg/kg, varied from 75% to 110%, with the relative standard deviations (RSDs) ranged from 1.7% to 11.6%. This method was utilized to detect the real samples in Shandong. 100 batches of forage grass were selected, and residues of 8 pesticides in those samples were detected. According to MRLs from China, USA and Japan, the residues in the samples were safe. The QuEChERS-GC-MS/MS method was established as a simple, rapid, cost-effective, sensitive and accurate method to detect the above 10 pesticide residues in forage grass.