表面解吸化学电离质谱法快速检测蔬菜中痕量氨基甲酸酯

Determination of Carbamate Pesticides in Vegetables by Surface Desorption Atomospheric Pressure Chemical Ionization Mass Spectrometry

采用自行研制的表面解吸常压化学电离源(SDAPCI),样品未经预处理用质谱法直接测定了克百威、灭多威和异丙威3种氨基甲酸酯农药在蔬菜表面的残留,并用串联质谱法对所获得的信号离子进行结构鉴定,排除了检测结果的假阳性。结果表明,克百威和灭多威分别形成m/z222和m/z163的质子化的分子离子信号,异丙威形成m/z193的自由基阳离子信号。串联质谱实验表明,3种氨基甲酸酯农药分子的裂解规律与其分子结构相吻合。表面解吸常压化学电离质谱法对待测样品无污染,方法检测限低于1.0×10-14g/cm2,单个样品的测定时间平均少于1s,特别适合于对批量样品进行快速检测。

Surface desorption atmospheric chemical ionization mass spectrometry （SDAPCI-MS） was used to directly determine pesticide residue on the surface of vegetables without any toxic chemical contamination. Three carbamate pesticides, carbofuran, isoprocarb and methomyl, were determined, and the structure of the molecular ions of each analyte was confirmed by collision-induced dissociation （CID） to exclude the fake positive conclusion. The results show that the carbofuran and methomyl exhibit protonated molecular ion signals at m/z 222 and m/z 163 respectively, but the isoprocarb displays free radical cation signal at m/z 193 under these conditions. The tandem mass spectrometry shows that the fragmentation regularity of the three carbamate pesticides coincide with their molecular structures. The detection limit of this method was found to be less than 1.0×10^-14 g/cm^2, and the detection time less than 1 s. SDAPCI-MS is a good method to inspect bulk samples nondestructively without sample pretreatment.