Determination of Organophosphorus Pesticides in Groundwater by Gas Chromatography Coupled with Closed Ultrasound Circulating Purge Needle Trap
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摘要:
基于针捕集适于免溶剂提取气态介质样品的特点, 通过蠕动泵将针捕集与水样组成闭合循环吹扫系统, 提高目标物的水样/顶空亨利系数, 建立了针捕集闭合循环提取耦合气相色谱快速分析地下水中4种半挥发性有机磷农药(敌敌畏、甲拌磷、甲基对硫磷、马拉硫磷)的方法, 该方法集采样、提取、净化、浓缩、色谱进样于一体。确定了针捕集提取水样最佳条件为:采样流速11.11 mL/min, 水样提取温度40℃, 在此条件下获得浓度均为1 mg/L的4种有机磷农药的针捕集吸附穿透体积, 其中甲基对硫磷最大为600 mL。以5 μg/L、50 μg/L和200 μg/L三个浓度水平的加标平均回收率为62.3%~103.0%, 除敌敌畏低浓度水平的RSD为26.1%外, 其余组分的RSD < 7.7%;方法检出限为0.016~0.157 μg/L, 接近或优于现行国标及相关研究结果。
Abstract:Based on the merits of solvent-free extraction of gaseous samples by needle trap, closed circulating purge system consisting of needle trap and water sample by peristaltic pump is established to enhance the Henry's law constant of analytes in the gas/liquid phase. In this study, the method for determination of dichlorvos, phorate, methyl parathion and malathion in groundwater by circulating extraction with needle trap coupled with Gas Chromatography was established. This method integrated sampling, extraction, purification, concentration, and chromatography. The optimum conditions for the extraction by needle trap include sampling flow rate of 11.11 mL/min and extraction temperature of 40℃. Under these conditions, the maximum breakthrough volume of 1 mg/L methyl parathion is 600 mL. The recoveries range from 62.3% to 103.0% for 5 μg/L, 50 μg/L and 200 μg/L analytes. Low level dichlorvos has a relative standard deviation of 26.1%, and other components are lower than 7.7%. The detection limits of the proposed method range from 0.016 to 0.157 μg/L, close to, or better than the current standard results and related study results.
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Key words:
- groundwater /
- organophosphorus /
- needle trap /
- extraction by purge /
- Gas Chromatography
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表 1 方法线性范围、相关系数、加标回收率和检出限
Table 1. Linear range, correlation coefficients, spiked recovery and detection limits of the method
目标物线性范围
(μg/L)相关
系数基质加标浓度
5 μg/L基质加标浓度
50 μg/L基质加标浓度
200 μg/L方法
检出限
(μg/L)平均
回收率
(%)RSD
(%)平均
回收率
(%)RSD
(%)平均
回收率
(%)RSD
(%)敌敌畏 50~200 0.9953 62.3 26.1 76.1 7.7 87.0 6.9 0.157 甲拌磷 5~500 0.9825 72.3 6.8 90.2 6.5 103.0 4.8 0.016 甲基对硫磷 5~500 0.9923 68.6 7.2 95.0 6.4 95.0 3.4 0.051 马拉硫磷 10~200 0.9989 74.9 7.5 93.9 4.3 91.0 4.3 0.063 
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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] EPA Method 524. 2, Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry[S]. 1995.
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