双柱定性气相色谱电子捕获检测器测定上海市饮用水中微量碘化物

目的 对目前国家生活饮用水标准检验方法中气相色谱测定碘化物的色谱条件、定性定量方法等进行改进和优化,并以该法测定上海市饮用水中碘化物含量.方法 先以气相色谱与质谱联用鉴定衍生化产物碘丁酮,再用双毛细管柱配合电子捕获检测器对碘丁酮进行定性定量分析,最后分别采集上海市以长江、黄浦江及其内河为水源的3家水厂原水和出厂水各100 ml测定水样中碘化物水平.结果 经质谱鉴定发现碘化物衍生化后生成碘丁酮存在2个同分异构体,即1-碘-2-丁酮和3-碘-2-丁酮.采用双毛细管柱定性分析显示,碘丁酮分离度好,整个色谱分离时间为19.33 min.选择响应值较高的3-碘-2-丁酮进行定量检测,方法线性范围为1～100μg/L,确定系数r2=0.9997;方法检出限为13 ng/L;样品加标回收率为97.68%～104.37%,相对标准偏差为2.14%～4.41%.该方法测定3家上海市不同水源水厂的原水和出厂水中碘化物含量结果发现,原水中碘化物浓度以黄浦江最高(15.14μg/L),内河次之(6.97 μg/L),长江最低(3.55μg/L);除水厂2出厂水中碘化物浓度下降外(水厂2原水中碘化物浓度为15.14 μg/L,出厂水中为1.81μg/L),水厂1和3均呈略微上升(水厂1和3原水中碘化物浓度分别为3.55、6.97 μg/L,出厂水中分别为5.92、9.62μg/L).所有水样经平行双样测定的相对偏差均≤9.73%.结论 改进后的方法灵敏度更高、定性定量更准确,适用于水中微量碘化物的分析.

Determination of trace iodide in drinking water in Shanghai by two columns and gas chromatography with electron capture detection

Objective To modify and optimize gas chromatographic conditions, qualitative and quantitative method on the base of the actual national standard detection method for drinking water on testing iodide with gas chromatography, and detect iodide in drinking water of Shanghai.Methods Iodobutanone derivative was identified by gas chromatography/mass spectrometry, then two capillary columns coupled to electron capture detector were made by qualitative and quantitative analysis.Finally, 100 ml water samples were collected respectively from raw water and finished water of three plants in which water sources were Yangtse river, Huangpu river, and inner river respectively and detected by this developed method.Results The results of mass spectrometry showed that iodide would form iodobutanone which could generate 1-iodo-2-butanone and 3-iodo-2-butanone isomers by derivatization.The data of qualitative analysis by two capillary columns revealed that iodobutanone was separated completely and the total time of chromatogram separation was 19.33 min.3-iodo-2-butanone with the high response value was selected to quantitatively analyse.The linear range was 1 - 100 μg/L,and the coefficient of determination (r2) was 0.9997.The limit of detection was 13 ng/L.Recoveries were between 97.68% and 104.37% ,and relative standard deviations were between 2.14% and 4.41%.The results of iodide detected by this method in raw water and finished water in three plants in Shanghai showed that the ranking of iodide's concentration in raw water was Huangpu river (15.14 μg/L) ＞ inner river (6.97 μg/L) ＞ Yangtse river (3.55 μg/L).The level of iodide in finished water of plant 1 (3.55 μg/L and 5.92 μg/L for raw and finished water respectively) and 3 ( 6.97 μg/L and 9.62 μg/L for raw and finished water respectively) increased slightly except for plant 2( 15.14 μg/L and 1.81 μg/L for raw and finished water respectively).The relative standard deviations of all water samples measured in duplicate were less than 9.73%.Conclusion The improved method possesses higher degree of sensitivity and accuracy of qualitative and quantitative analysis than actual national standard detection method, and it is fit for trace analysis of iodide in water.