摘要
酰胺类农药在除草剂中应用广泛且易渗透转移到地表水和浅层地下水中,有机氯农药曾在环境中大量应用,且半衰期长,不易降解,这两类农药对人体都有较大的危害.但现行标准中无同时测定水体中酰胺类农药和有机氯农药的方法,为了提高工作效率和综合筛选评价需要,目前急需建立一种能够同时测定两类农药的方法.通过液液萃取增加环境样品的富集倍数,将定容好的样品经过气相色谱分离,以保留时间和特征离子定性和定量.鉴于GC法和LC法用于定性时容易出现结果假阳性,该文选择液液萃取GC/MS法,通过大量实验讨论了样品萃取pH值,萃取溶剂种类,萃取次数,萃取溶剂体积等条件对两类农药测定的影响,得到了良好的准确度与精密度,确定了最优条件,即 pH 为中性,萃取溶剂为正己烷,萃取次数为 1 次,250 mL水样萃取溶剂体积 25 mL 为最优条件.相关系数为 0.996～0.9999,检出限为 0.021～0.054 μg/L,加标回收率为65.9%～105.9%,精密度为 1.70%～8.50%.并在饮用水源地和长江支流检测实际水样开展了方法验证,2 个饮用水水源地点位上所有目标物均未检出,3 个支流上的点位有异丙甲草胺、乙草胺等 7 种农药检出,其余 25 种农药未检出;通过对实际水样的检测,证明了该方法在实际应用中的可行性.
Abstract
Amide pesticides are widely used in herbicides and are easy to penetrate and transfer to surface water and shallow groundwater.Organochlorine pesticides have been widely used in the environment with long half-lives and are not easily degraded.Both types of pesticides pose significant harm to human health.However,there is no method in the current standards for simultaneous determination of amide pesticides and organochlorine pesticides in water.In order to improve work efficiency and meet the needs of comprehensive screening and evaluation,there is an urgent need to establish a method that can simultaneously determine both types of pesticides.By increasing the enrichment factor of environmental samples through liquid-liquid extraction,the fixed volume samples are separated by gas chromatography to determine the retention time and characteristic ions for qualitative and quantitative analysis.Considering that GC and LC methods are prone to false positive results when used for qualitative analysis,this article chooses liquid-liquid extraction GC/MS method and discusses the effects of sample extraction pH value,extraction solvent type,extraction frequency,and extraction solvent volume on the determination of the two types of pesticides through a large number of experiments.Good accuracy and precision have been obtained,and the optimal conditions have been determined,namely pH being neutral,extraction solvent being n-hexane,and extraction frequency being 1,The optimal condition is to extract a solvent volume of 25mL from a 250mL water sample.The correlation coefficient is 0.996～0.9999,and the detection limit is 0.021～0.054 μ G/L,with a recovery rate of 65.9%～105.9%and a precision of 1.70%～8.50%.And method validation was carried out on actual water samples from drinking water sources and Yangtze River tributaries.All target substances were not detected at 2 drinking water source locations,7 pesticides such as metoclopramide and acetochlor were detected at 3 tributary locations,and the remaining 25 pesticides were not detected.The feasibility of this method in practical applications has been demonstrated through the detection of actual water samples.
基金项目
三峡库区生态环境教育部工程研究中心开放基金(2022)(KF2022-03)
NETL
NSTL
万方数据