蔬菜和水果中有机磷农药的双柱气相色谱测定法

Study on Application of Confirmatory Determination of Organophosphorus Pesticides in Vegetables and Fruits by Dual-column-dual-detector Gas Chromatography Method

目的建立蔬菜和水果中有机磷农药残留的双柱气相色谱检测法。方法向样品中加入适量水和硫酸钠,用乙酸乙酯振荡、离心、提取样品中残留的有机磷农药,提取液经浓缩、活性炭柱净化,然后用配有的毛细管柱DB-1701(中等极性)和HP-5(弱极性)、火焰光度检测器(FPD)和氮磷检测器(NPD)的气相色谱仪测定。以两种组合保留时间与标准品误差均不超过5%,定量误差不超过10%作为确证条件,以两者外标法定量平均值作为检测结果。结果在0.02～1.00 mg/L范围内,甲胺磷、乙酰甲胺磷、甲拌磷、乐果、毒死蜱、甲基对硫磷、马拉硫磷、杀螟硫磷、三唑磷的均呈线性关系,检出低限在0.01～0.02mg/kg,相关系数均大于0.996。9种有机磷农药在0.02、0.1、1.0mg/kg水平的回收率为84.0%～106.0%, RSD为3.0%～9.2%。结论该方法的准确度和精密度符合残留分析质量的要求,并且能有效区分目标化合物和各种干扰物,满足日常检测的确证需要。

Objective To develop a dual-column-dual-detector gas chromatography method for confirmatory determination of organophosphorus pesticides in vegetables and fruits. Methods After adding water and sodium sulphate, the sample was vortexed and centrifuged with ethyl acetate. The extract was concentrated then purified with active carbon SPE column. The residues were undergoing simultaneous confirmatory determination and external standard quantification using gas chromatography with dualcolumn（DB-1701 and HP-5） and dual-detector（nitrogen phosphorus deteetor-NPD and flame photometric detector-FPD）. While in both combinations the differences of the retention times between the sample and the standard material are not larger than 5%,at the same time the difference of the quantification results are not more than 10%,the target pesticide can be confirmed. Results It was showed that the limit of detection （LOD） for 9 organophosphorus pesticides （methamidophos, acephate, phorate, dimethoate, chlorpyrifos, methyl parathion, malathion, fenitrothion, triazophos） were as low as 0.01 -0.02 mg/kg respectively. The recovery rates for spiked standards ranged from 84.0% to 106.0%, with coefficients of variation of 3.0%-9.2%. Conclusion The precision and accuracy of this method conforms to the requirement of residues analysis,and by using this method target pesticide residues can be effectively resolved from various interferences, which meets the need for daily work of residues detection.