分散固相萃取-气相色谱-质谱法测定果蔬汁中6种有机磷农药的残留量

Determination of 6 organophosphorus pesticides in fruit and vegetable juice by dispersing solid phase extraction-gas chromatography-mass spectrometry

目的建立分散固相萃取-气相色谱-质谱法测定果蔬汁中6种有机磷农药残留量的分析方法。方法样品经二氯甲烷提取,采用分散固相萃取(QuEChERS)技术(C_(18) 500 mg+PSA 500 mg+GCB 60 mg)净化,氮吹浓缩后用正己烷定容,最后通过气相色谱-质谱仪测定,同时采用标准溶液曲线进行校准,内标法定量。结果本方法果蔬汁中敌敌畏、甲胺磷、乐果、毒死蜱、马拉硫磷和杀螟硫磷的检出限分别为:0.0009、0.0103、0.0095、0.0012、0.0012、0.0010 mg/kg,6种化合物在0.05~1.0 mg/L线性范围内线性关系均良好(r>0.990),在0.02、0.04、0.1 mg/kg的添加水平下,各化合物的回收率均介于73.0%~102.7%之间,相对标准偏差(n=6)在1.3%~3.7%之间,且处理后的样液在24 h内稳定。结论本方法灵敏度高,回收率、精密度和重现性均较好,准确度高,适用于对果蔬汁中6种有机磷农药残留量进行定性和定量检测。

Objective To establish an analysis method for determination of 6 kinds of organophosphorus pesticide residues in fruit and vegetable juice by dispersing solid phase extraction-gas chromatography-mass spectrometry （QuEChERS-GC-MS）. Method The samples were extracted by dichloromethane, cleaned by QuEChERS （C18 500 mg＋GCB 60 mg＋PSA 500 mg） purification, concentrated by the nitrogen blow, and then diluted with hexane to volume. At last, they were detected by GC-MS. Standard solution calibration curve was used at the same time and internal standard method was quantitated. Results The results showed that the limits of detection （LODs） of dichlorvos, methamidophos, dimethoate, chlorpyrifos, malathion and fenitrothion were 0.0009, 0.0103, 0.0095, 0.0012, 0.0012 and 0.0010 mg/kg, respectively. There were good linear relationships for 6 compounds in the linear range of 0.05-1.0 mg/L （r〉0.990）. At the spiked levels of 0.02, 0.04 and 0.1 mg/kg, the recoveries of all compounds were between 73.0%-102.7%, relative standard deviations （n=6） were between 1.3%-3.7%, and the processed samples were stable within 24 h. Couelusion This method has high sensitivity, good recovery, precision and reproducibility, and high accuracy, which is suitable for qualitative and quantitative detection of 6 organophosphorus pesticide residues in fruit and vegetable juice.