饮用水中二氯乙酸、三氯乙酸的自动顶空-气相色谱测定法

Determination of dichloroacetic acid and trichloroacetic acid in drinking water by headspace gas chromatography

目的建立自动顶空-气相色谱法测定饮用水中二氯乙酸(DCAA)、三氯乙酸(TCAA)的分析方法。方法准确移取10 m L待测水样于20 mL顶空瓶中,依次加入5 g无水硫酸钠、50μL硫酸溶液(1 mol/L)、150μL四丁基硫酸氢铵溶液(1 mol/L)、500μL硫酸二甲酯及300μL正戊烷立即加盖密封并充分震荡混匀2 min,自动顶空-气相色谱法测定,外标法定量。结果本法二氯乙酸在5~300μg/L、三氯乙酸在10~600μg/L范围内线性关系良好,相关系数(r)均大于0.999,二氯乙酸、三氯乙酸方法检出限(LOD)分别为0.60和0.24μg/L。饮用水中二氯乙酸和三氯乙酸平均加标回收率在96.1%~114.2%,相对标准偏差(RSD)在3.82%~9.36%。结论本法简单、灵敏、准确,适用于饮用水中二氯乙酸和三氯乙酸的检测。

Objective To establish an automatic headspace gas chromatography method for the determination of dichloroacetic acid(DCAA) and trichloroacetic acid(TCAA) in drinking water. Methods 10 mL drinking water sample was removed into a 20 mL headspace vial,and added 5 g anhydrous sodium sulfate,50 μL sulfuric acid solution(1.0 mol/L),150 μL tetrabutylammonium hydrogen sulfate solution(1.0 mol/L),500 μL dimethyl sulfate and 300 μL n-pentane successively. The target compounds were detected by automatic headspace gas chromatography and quantified with the external standard method. Results DCAA and TCAA had good linearity in the range of 5-300 and 10-600 μg/L respectively,with the correlation coefficients(r) higher than 0.999. The limit of detection(LOD) for DCAA and TCAA was 0.60 and 0.24 μg/L respectively. The average recoveries of DCAA and TCAA in drinking water were 96.1%-114.2%,and the relative standard deviations(RSD)were 3.82%-9.36%. Conclusion The developed method was shown to be convenient,sensitive,and accurate. It is suitable for the determination of dichloroacetic acid and trichloroacetic acid in drinking water.