QuEChERS样品前处理-液相色谱-串联质谱法测定蔬菜中66种有机磷农药残留量方法评估

比较了两种版本QuEChERS方法(即发表于2003年未加缓冲盐的原创QuEChERS方法及加乙酸盐缓冲液的AOAC 2007.01方法)提取蔬菜中66种有机磷农药(OPPS)的有效性;考察了乙二胺-N-丙基硅烷(PSA)及C18吸附剂对66种OPPS的吸附作用;以提取后添加法评估了青花菜、番茄、枝豆、萝卜、大葱基质中各目标物液相色谱-串联质谱(LC-MS/MS)分析的基质效应。结果表明,加入乙酸盐缓冲液的QuEChERS方法对一些OPPS有较高及较稳定的回收率;PSA及C18吸附剂可吸附二溴磷,QuEChERS样品前处理方法不适于二溴磷分析;5种样品基质中青花菜的基质效应最大。据此采用AOAC 2007.01方法并优化LC-MS/MS分析参数,一次进样监测132对离子对(每个化合物2对离子对)分析蔬菜中66种OPPS残留量,除二溴磷外,65种OPPS在5种基质(青花菜、番茄、枝豆、萝卜、大葱)、3个添加水平(10、40、80 μg/kg)的回收率为55%～122%,相对标准偏差为1.6%～18%,定量限(以信噪比(S/N)≥10计)为0.1～8 μg/kg。以上结果说明该法有效、耐用、灵敏,符合法规残留限量监测要求。

Evaluation of QuEchERS methods for the analysis of 66 organophosphorus pesticide residues in vegetables by liquid chromatography-tandem mass spectrometry

A comparison was made between the two versions of QuEChERS sample preparation method for the extraction of 66 organophosphorus pesticides (OPPS) in vegetables. The two QuEChERS methods were the original method without buffer published in 2003, and the AOAC Official Method 2007. 01 with acetate buffer. The adsorption behaviors of primary secondary amine (PSA) sorbent and C18 sorbent on the OPPS were studied. The method of after-extraction addition was used to evaluate matrix effects for OPPS in matrix of broccoli, tomato, green soybean, radish and shallot during liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. As a result, the QuEChERS method with acetate buffer gave higher and more consistent recoveries for some of OPPS. The PSA sorbent and C18 sorbent can adsorb dibrom, so the QuEChERS method was not suitable for the analysis of dibrom. The maximum matrix effects were in the extracts of broccoli during LC-MS/MS analysis. In this article, OPPS were extracted using the QuEChERS method with acetate buffer, and analysed by LC-MS/MS under the optimized conditions with monitoring 132 MS/MS transitions of precursor ions (two for each pesticide) in one single run. Recoveries for all but dibrom at fortification levels of 10, 40, 80 microg/kg in broccoli, tomato, green soybean, radish and shallot ranged from 55% to 122% with relative standard deviations of 1.6% - 18%. The limits of quantification (S/N > or = 10) were 0.1 - 8 microg/kg. Based on these results, the analytical method was proven to be highly efficient, robust and sensitive, and suitable for the monitoring of the maximum residue limits (MRLs) of 66 OPPS in vegetables.