气相色谱-负化学电离源-飞行时间质谱测定烟草中有机氯农药残留

采用QuEChERS前处理方法,建立了气相色谱-负化学电离源-飞行时间质谱(GC-NCI-TOF-MS)检测烟草中10种有机氯农药残留的分析方法。样品采用乙酸乙酯-正己烷(1 : 1, v/v)溶液提取,提取液经N-丙基乙二胺(PSA)、无水硫酸镁分散固相萃取净化,用GC-NCI-TOF-MS检测分析。根据有机氯化合物特征离子的精确质量数、同位素离子峰簇、碎片离子丰度比和保留时间对目标物定性鉴定,外标法定量。10种有机氯农药的线性关系良好,相关系数 (r²)均大于0.997;相对标准偏差小于6.5%;检出限为0.04~0.80 μ g/kg;加标回收率为77.2%~93.0%。该方法简单快速、灵敏度高、准确性好,适用于烟草中有机氯农药残留的定性分析和定量检测。

Determination of organochlorine pesticide residues in tobacco by gas chromatography-negative chemical ionization-time of flight mass spectrometry

A method was developed for the determination of 10 organochlorine pesticide (OCP) residues in tobacco by gas chromatography-negative chemical ionization-time of flight mass spectrometry (GC-NCI-TOF-MS) coupled with QuEChERS method. The extraction and purification procedures for tobacco samples, the chromatographic conditions and TOF-MS conditions of the analytes were critically examined. Tobacco samples were extracted with ethyl acetate-hexane (1 : 1, v/v) and cleaned up by primary secondary amine (PSA) and MgSO₄, then detected by GC-NCI-TOF-MS. Accurate mass analysis, isotopic peak clusters, fragment ion abundance ratio and retention time were employed to qualitative identification and external standard method was used for quantitative determination. The results indicated that the correlation coefficients (r²) were better than 0.997, and the relative standard deviations (RSDs) were less than 6.5%. The limits of detection and the limits of quantification were 0.04 to 0.80 μ g/kg and 0.13 to 2.64 μ g/kg, respectively. The recoveries of the 10 organochlorine pesticides at three spiked levels ranged from 77.2% to 93.0%. It was proved that the method is simple, rapid, with high accuracy and high sensitive. It is appropriate for the detection and determination of organochlorinepesticide residues in tobacco samples.