柱前衍生-气相色谱法测定饮用水中的2,4-滴

Determination of 2,4-D in drinking water by pre-column derivatization-gas chromatography

目的建立柱前衍生-气相色谱法测定饮用水中的2,4-滴的方法。方法取200 ml经过酸化的水样(p H值<1),用二氯甲烷萃取,无水硫酸钠脱水,旋转蒸发仪浓缩至近干,加入甲醇∶三氟化硼乙醚(9∶1,V/V)溶液于90℃加热30 min衍生,放冷后用正己烷提取,上清液经HP-5色谱柱(30 m×320μm,0.25μm)分离后,ECD检测,标准曲线法定量。结果2,4-滴在0μg/L^100μg/L时保持良好的线性关系(r=0.9993)。线性范围比国家标准法扩大了4倍。回归方程y=283.20x+240.9,方法最低检出质量浓度为0.039μg/L,低于国家标准要求的0.05μg/L。相对标准偏差(RSD)为1.2%。分别做了低、中、高3个浓度的加标回收实验,回收率为91.2%~102.8%。结论本方法简便、快速、准确、灵敏度高、反应条件容易控制,适用于基层实验室对饮用水中2,4-滴的检测。

Objective To establish a method for the determination of 2,4-D in drinking water by pre-colum derivatization-gas chromatography.Methods A total of 200 ml acidified water sample(p H<1)was extracted with dichloromethane,dehydrated with anhydrous sodium sulfate,then was concentrated to near dryness by rotary evaporator.The extracted solution was derivatized with boron trifluoride-diethyl-ether(9:1,V/V)in methanol at 90℃water bath for 30 min.After derivatization,the derivative was extracted with n-hexane,then separated with HP-5 column(30 m×320μm,0.25μm)and detected with ECD.The quantification was based on standard curve method.Results A good linear relationship was obtained within0μg/L-100μg/L(r=0.9993),which was four times wider than the national standard method.The regressive equation was y=283.20 x+240.9,with detection limit of 0.039μg/L which was less than the national standard requirement of 0.05μg/L.The relative standard deviation(RSD)of the method was 1.2%.The standard addition recovery experiments of low,medium and high concentration in drinking water were carried out.The recovery rates were within 91.2%-102.8%.Conclusion The method is simple,rapid,accurate,and sensitive,and it is suitable for the detection of 2,4-D in drinking water in grassroots laboratories.