顶空-气相色谱法测定水中三氯甲烷和四氯化碳方法的改进

改进了顶空-气相色谱法测定水中三氯甲烷和四氯化碳的方法,对平衡温度和平衡时间进行了优化,对不同溶剂配制的标准使用液和不同方法制作的工作曲线对测定结果的影响进行了比较.试验结果表明,样品最佳平衡温度和时间分别为50℃和35 min.采用甲醇代替标准中规定的纯水配制标准使用液,采用微量进样针取样到预先密封的顶空瓶中,三氯甲烷和四氯化碳在较宽的质量浓度范围内(分别为1~100μg/L和0.1~10μg/L)线性关系良好,相关系数达到0.999以上,方法检出限分别为0.027和0.0014μg/L.三氯甲烷和四氯化碳的回收率分别为98.3%~103.0%和94.3%~105.0%,相对标准偏差分别为0.76%~1.23%和1.96%~2.47%.方法拓宽了标准方法中的工作曲线范围,准确度高,操作简单,适用于环境水和饮用水的大批量分析.

Improved Method of Headspace-Gas Chromatography for Determination of Trichloromethane and Carbon Tetrachloride in Water

The method of headspace-gas chromatography (HS-GC) for the determination of trichloromethane and carbon tetrachloride in water was improved. The equilibrium temperature and time were optimized. The influence of different solvents on standard working solution preparation was investigated, and the different preparation modes of working curves were compared. The results showed that the optimal equilibrium temperature and time were 50 ℃ and 35 min, respectively. When the methanol standard working solution was used instead of pure water, and the standard working solution was injected into the pre-sealed headspace bottle with micro injection needle, all the linear relationship of trichloromethane and carbon tetrachloride were good in a wide range of mass concentration (1~100 μg/L and 0.1~10 μg/L, respectively), and all the correlation coefficient were above 0.999. The limits of detection were 0.027 μg/L for trichloromethane and 0.001 4 μg/L for carbon tetrachloride. The recoveries were 98.3%~103.0% and 94.3%~105.0%, respectively, and relative standard deviations were 0.76%~1.23% and 1.96%~2.47%, respectively. The above results indicated that the HS-GC method is accurate, convenient and has a wider linear range, which is suitable for the analysis of bulk samples of environmental and drinking water.