Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, E-14071 Córdoba, Spain.
J Chromatogr A. 2013 Sep 13;1307:158-65. doi: 10.1016/j.chroma.2013.07.065. Epub 2013 Jul 23.
Low-molecular-mass aldehydes (LMMAs) are water disinfection by-products formed by the reaction of ozone and/or chlorine with natural organic matter in water. LMMAs are mutagenic and carcinogenic compounds, which are detected at ng/L levels in water. An analytical method that allows simultaneous derivatisation and extraction of LMMAs in water has been developed using the classical static headspace technique coupled with gas chromatography-mass spectrometry (HS-GC-MS). Important parameters controlling the derivatisation of LMMAs with o-2,3,4,5,6-pentafluorobenzylhydroxylamine, oxime-products extraction and headspace generation were optimised to obtain the highest sensitivity, completing the entire process in 20min. For the first time the derivatisation reaction was carried out at alkaline pH adjusted with sodium hydrogen carbonate which exerts a significant enhancement effect on the derivatisation efficiency of the aldehydes; up to 20-fold with respect to those obtained in weak acid media as recommended by EPA Method 556.1. The addition of 200μL of n-hexane, as a chemical modifier, favoured the volatilisation of oxime-products, increasing the sensitivity of the method. The proposed method allows the achieving of detection limits from 2 to 80ng/L and has excellent precision (RSD average value of 6.4%) and accuracy (recovery ranging from 97% to 99%) for LMMA quantifications in drinking water samples. Finally, the HS-GC-MS method was validated relative to EPA Method 556.1 for the analysis of drinking water samples subjected to several disinfection treatments.
低相对分子质量醛类（LMMAs）是臭氧和/或氯与水中天然有机物反应形成的水消毒副产物。LMMAs 是致突变和致癌的化合物，在水中以 ng/L 水平检测到。本研究采用经典静态顶空技术与气相色谱-质谱联用（HS-GC-MS）联用，开发了一种可同时衍生和提取水中 LMMAs 的分析方法。使用邻-2,3,4,5,6-五氟苯羟胺对 LMMAs 进行衍生化、肟产物提取和顶空生成的重要参数进行了优化，以获得最高的灵敏度，整个过程在 20min 内完成。首次在碳酸氢钠调节的碱性 pH 下进行衍生化反应，这对醛类的衍生化效率有显著的增强作用；与 EPA 方法 556.1 推荐的弱酸介质相比，提高了 20 倍。添加 200μL 正己烷作为化学修饰剂，有利于肟产物的挥发，提高了方法的灵敏度。该方法可实现检测限为 2-80ng/L，在饮用水样品中对 LMMAs 的定量具有极好的精密度（RSD 平均值为 6.4%）和准确性（回收率在 97%-99%之间）。最后，相对于 EPA 方法 556.1 对经过多种消毒处理的饮用水样品进行了 HS-GC-MS 方法验证。
