QuEChERS-高效液相色谱-串联质谱法测定牛生乳中12种脂溶性农药及其3种代谢物残留

    Determination of 12 lipid soluble pesticides and three metabolites in raw milk by QuEChERS-high performance liquid chromatography-tandem mass spectrometry

    • 摘要: 采用QuEChERS前处理结合高效液相色谱-串联质谱(HPLC-MS/MS)建立了牛生乳中12种脂溶性农药及其3种代谢物的多残留分析方法,包括抑霉唑、环丙唑醇、啶氧菌酯、吡氟酰草胺、茚虫威、虱螨脲、乙螨唑、唑螨酯、炔草酯及其代谢物炔草酸、肟菌酯及其代谢物肟菌酸、氟吡乙禾灵、氟吡甲禾灵及其代谢物氟吡禾灵。样品经10 mL体积分数为1%的甲酸乙腈提取,冷冻5 h后经100 mg C18净化,上清液过0.22 μm有机系滤膜后,采用HPLC-MS/MS测定。结果表明:15种目标分析物在0.01~1 mg/L范围内,其进样质量浓度与峰面积间具有良好线性关系,决定系数 (R2) ≥ 0.9954。在0.01、0.1和1 mg/kg 3个添加水平下,15种目标分析物在牛生乳中的平均回收率在87%~109%之间,相对标准偏差为0.30%~11% (n = 5),方法的定量限在0.001~0.01 mg/kg之间,检出限在0.0003~0.003 mg/kg之间,满足农药残留分析的要求。利用该方法对我国牛生乳3个主产区30份抽检样品进行测定。结果显示:21份样品中乙螨唑的残留量大于方法的检出限,但小于方法定量限,1份样品中乙螨唑的残留量为0.0036 mg/kg;其余14种目标物的残留量均小于方法的检出限。该方法适用于牛生乳中农药残留的快速检测,可为我国牛生乳中12种脂溶性农药的最大残留限量(MRLs)的建立及膳食风险评估提供参考。

       

      Abstract: A multi-residue analytical method for 12 lipid soluble pesticides and three metabolites in raw milk was established using QuEChERS sample preparation combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The target compounds included imazalil, cyproconazole, picoxystrobin, diflufenican, indoxacarb, lufenuron, etoxazol, fenpyroximate, clodinafop-propargyl and its metabolites clodinafop, trifloxystrobin and its metabolites trifloxystrobin acid, haloxyfop-etotyl, haloxyfop-methyl and their metabolite haloxyfop. The sample was extracted by 10 mL of 1% formic acid in acetonitrile, cleaned-up by 100 mg C18 after being frozen for 5 h. The supernatant was filtered through a 0.22 μm organic membrane and determined by HPLC-MS/MS. The results showed that there were good linearity between the mass concentration and peak area of the 15 target analytes in the range of 0.01 to 1 mg/L, and the determination coefficient (R2) were higher than 0.9954. The average recoveries of the 15 target analytes in raw milk at the three spiked levels of 0.01, 0.1 and 1 mg/kg ranged from 87% to 109%, with relative standard deviations of 0.30% to 11% (n = 5). The limits of quantification (LOQ) of the method ranged from 0.001 to 0.01 mg/kg, and the limits of detection (LOD) were 0.0003-0.003 mg/kg. The validation results met the requirements of the pesticide residue analysis. The method was used to determine 30 samples from three main producing areas of raw milk in China. The results showed that the residue of etoxazol in 21 samples was greater than the LOD, but lower than the LOQ. The residue of etofenprox in the other sample was 0.0036 mg/kg. The residual amounts of the remaining 14 target compounds were all lower than their LODs. The method is suitable for the rapid determination of pesticide residues in raw milk, and provides a reference for the establishment of maximum residue limits (MRLs) of the 12 lipid soluble pesticides in raw milk and the dietary risk assessment in China.

       

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