非接触热解析封闭式低温等离子体电离源质谱法快速分析3种农药残留

Rapid Analysis of Three Kinds of Pesticide Residues by Non-contact Thermal Desorbing and Closing Low Temperature Plasma Ionization Mass Spectrometry

利用低温等离子体电离源微型离子阱质谱建立了一种常压离子化质谱直接、快速、定量分析农药残留的新方法.低温等离子体电离源与质谱进样口处于封闭金属腔体内部,在负离子探测模式下,将样品放置于低温等离子体电离源前的采样平台上,利用卤素灯快速无接触热解析样品.结果表明,封闭离子源更具优势,通过对加热时间、辅助气流流量等条件的优化,实现了对3种农药在0.5～ 10 mg/L范围内的定量分析,相对标准偏差控制在11％左右,5 s内的样品检出限均在Pg量级.该检测方法无需样品前处理,样品可直接检测,分析时间快,有望广泛应用于有机和绿色果蔬中农药残留的快速检测.

A new method was established for the direct, rapid and quantitative analysis of pesticide residues, dimethoate chlorothalonil and malathion by low temperature plasma （LTP） ionization miniature ion trap mass spectrometer. The LTP ionization probe and sample inlet of ion trap mass spectrometry were enclosed in a metal cavity. With non-contact heating, the samples placed on the sample platform were desorbed into gaseous phase and ionized by LTP ionization probe. The results showed that closed ionization had an edge over the opened ionization. The quantitative analysis of 3 pesticides within the range of 0.5-10 mg/L was realized by optimizing heating time and flow rate of air, and the relative standard deviations of signal intensity is less than 11%. LODs of pesticide, which were obtained within 5 s, were as low as several hundred pictograms. The results showed that the method could be used for the analysis of pesticide residue on green and organic fruits or vegetables.