基于酶抑制原理的电喷雾质谱法快速筛查蔬菜中氨基甲酸酯类农药残留

摘要

采用电喷雾质谱( ESI-MS),通过测定乙酰胆碱酯酶( Acetylcholinesterase, AChE)的抑制率,建立了蔬菜中氨基甲酸酯类农药( Carbamate pesticides, CBPs)残留的快速筛查方法。样品经QuEChERS方法简单处理后,以硫代乙酰胆碱为底物,与AChE发生酶促反应,用ESI-MS法测定底物转化成产物硫代胆碱的转化率,进而计算得到AChE的抑制率。本实验优化了酶促反应温度、时间及浓度等条件,考察了10种常见CBPs农药浓度与AChE抑制率的关系,研究了实际蔬菜样品存在的基质效应,以不含农药的空白蔬菜样品的酶抑制率的3倍确立了方法的检出限。结果表明,方法检出限可达到0.01~0.05 mg/kg,优于现行的农药残留快速筛查国家标准,完全满足食品安全国家标准对食品中农药最大残留限量的要求,且具有良好的抗基质干扰能力,可有效避免假阳性结果的出现,并通过了液相色谱-串联质谱法的验证。本方法简便快速、灵敏可靠,适用于蔬菜中氨基甲酸酯类农药的快速、高通量筛查。%Arapidscreeningmethodforthedeterminationofcarbamatepesticides(CBPs)residuesin vegetables by measuring acetylcholinesterase ( AChE ) inhibition rate using electrospray ionization mass spectrometry ( ESI-MS ) has been established. After pretreatment by QuEChERS method, sample solution reacts with AChE using acetylthiocholine as substrate. AChE inhibition rate was calculated by determination of the conversion of substrate to product ( thiocholine) using ESI-MS. The temperature, time and concentration conditions of enzymatic reactions have been optimized. The relationship between the concentration of 10 kinds of common CBPs and AChE inhibition rate was researched. Matrix effects of real vegetables were studied. The limit of detection ( LOD) , which was measured by 3 times of enzyme inhibition rate of pesticide-free vegetable samples, was 0. 01-0. 05 mg/kg. The results showed that the method was better than the current national standard method of china for rapid screening of pesticide residues and fully meet the requirements of maximum residue limits( MRL) for pesticides in food of national food safety standard. False positive results were avoided effectively due to its good ability of resistance matrix interference. The reliability was proved by analyzing vegetables with liquid chromatography-tandem mass spectrometry. The method is simple, rapid, sensitive, reliable, and can be used for the rapid, high-throughput screening of CBPs in vegetables.