气相色谱法测定饮用水中挥发性卤代烃的不确定度评定

目的建立自动顶空毛细柱气相色谱法测定饮用水中三氯甲烷、四氯化碳、二氯一溴甲烷、一氯二溴甲烷、三溴甲烷等挥发性卤代烃的不确定度评定方法，以评定测量结果的质量。方法根据GB／T5750．8—2006（（生活饮用水标准检验方法》建立数学模型，逐一分析量化测量过程中的不确定度分量，计算合成标准不确定度和扩展不确定度。结果三氯甲烷含量为5．88μg／L时，U=0．42μg/WL，k=2；四氯化碳含量为1．98μg/L时，U=0．18μg/E，％=2；二氯一溴甲烷含量为12．60μg/L时，U=0．72μg/WE，k=2；一氯二溴甲烷含量为6．00μg/WL时，U：0．36μg/L，k=2；三溴甲烷含量为5．55μg／L时，U=0．38μg/WE，％=2。结论曲线拟合和标准溶液带来的不确定度是测量结果不确定度的主要来源，此方法适用于饮用水中挥发性卤代烃的不确定度评定。

The uncertainty evaluation for the determination of volatile halogenated hydrocarbons in drinking water by gas chromatographic method

Objective To establish the method of uncertainty evaluation for determination of chloroform, carbon tetrachlo- ride, Bromodichloromethane, chlorodibromomethane and tribromethane in drinking water by automatic headspace capillary gas chromatography method, assess the quality of the measurement results. Methods According to GB/T 5750. 8 - 2006, the mathematical model was established, quantitative component of uncertainty was analyzed in the measurement process, combined standard uncertainty and expanded uncertainty were calculated. Results When Chloroform content was 5.88 μg/ L, U was 0. 42 μg/L, k = 2 ; Carbon tetrachloride content wasl. 98 μg/L, U was 0. 18μg/L, k = 2 ; Bromodichloromethane content was 12. 60μg/L, U was 0. 72 μg/L, k = 2 ;chlorodibromomethane content was 6. 00μg/L, U was 0. 36 μg/L, k = 2 ; tribromethane was 5.55 μg/L, U was 0. 38 μg/L,k = 2. Conclusion Curve fitting and standard solution offered by uncer-tainty are the main sources of uncertainty in measurement, This method is suitable for volatile halocarbons in drinking water of uncertainty.