Key Laboratory of Public Health and Safety, Ministry of Education, Department of Environment Health, School of Public Health, Fudan University, Shanghai, China.
PLoS One. 2013 Apr 16;8(4):e60858. doi: 10.1371/journal.pone.0060858. Print 2013.
An optimized method is presented using liquid-liquid extraction and derivatization for the extraction of iodoacetic acid (IAA) and other haloacetic acids (HAA9) and direct extraction of iodoform (IF) and other trihalomethanes (THM4) from drinking water, followed by detection by gas chromatography with electron capture detection (GC-ECD). A Doehlert experimental design was performed to determine the optimum conditions for the five most significant factors in the derivatization step: namely, the volume and concentration of acidic methanol (optimized values = 15%, 1 mL), the volume and concentration of Na2SO4 solution (129 g/L, 8.5 mL), and the volume of saturated NaHCO3 solution (1 mL). Also, derivatization time and temperature were optimized by a two-variable Doehlert design, resulting in the following optimized parameters: an extraction time of 11 minutes for IF and THM4 and 14 minutes for IAA and HAA9; mass of anhydrous Na2SO4 of 4 g for IF and THM4 and 16 g for IAA and HAA9; derivatization time of 160 min and temperature at 40°C. Under optimal conditions, the optimized procedure achieves excellent linearity (R(2) ranges 0.9990-0.9998), low detection limits (0.0008-0.2 µg/L), low quantification limits (0.008-0.4 µg/L), and good recovery (86.6%-106.3%). Intra- and inter-day precision were less than 8.9% and 8.8%, respectively. The method was validated by applying it to the analysis of raw, flocculated, settled, and finished waters collected from a water treatment plant in China.
本文提出了一种优化的液-液萃取和衍生化方法，用于从饮用水中提取碘乙酸（IAA）和其他卤乙酸（HAA9），以及直接提取碘仿（IF）和其他三卤甲烷（THM4），然后通过带有电子捕获检测（GC-ECD）的气相色谱法进行检测。采用 Doehlert 实验设计确定了衍生化步骤中五个最重要因素的最佳条件：即酸性甲醇的体积和浓度（优化值= 15%，1 mL）、Na2SO4 溶液的体积和浓度（129 g/L，8.5 mL），以及饱和 NaHCO3 溶液的体积（1 mL）。此外，通过双变量 Doehlert 设计优化了衍生化时间和温度，得到以下优化参数：IF 和 THM4 的萃取时间为 11 分钟，IAA 和 HAA9 的萃取时间为 14 分钟；IF 和 THM4 的无水 Na2SO4 质量为 4 g，IAA 和 HAA9 的无水 Na2SO4 质量为 16 g；衍生化时间为 160 min，温度为 40°C。在最佳条件下，优化后的方法具有良好的线性（R2 范围为 0.9990-0.9998）、低检测限（0.0008-0.2 µg/L）、低定量限（0.008-0.4 µg/L）和良好的回收率（86.6%-106.3%）。日内和日间精密度均小于 8.9%和 8.8%。该方法已应用于中国某水厂原水、絮凝水、沉淀水和出水的分析验证。
