饮用水中高分子量消毒副产物的检测识别方法

Detection and identification of high-molecular-weight disinfection byproducts in drinking water

消毒是饮用水处理过程中的重要步骤,但普遍采用的氯系消毒剂在杀灭细菌病毒的同时,能产生大量具有“三致”效应的卤代消毒副产物(DBPs),严重威胁了饮用水的化学安全.研究人员已在饮用水中陆续检测并识别出700多种DBPs,但这些已知DBPs均为分子量小于800 Da的低分子量DBPs,目前对高分子量DBPs的认识还较为有限.本研究建立了基于基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)的高分子量DBPs检测方法,发现在基质为2,5-二羟基苯甲酸,阳离子化试剂为三氟乙酸钠,使用三明治法点靶,反射-正离子模式,90%激光强度时,信噪比和信号重现性达到最优,信噪比之和达到了136.2,变异系数(CV)则为4.77%.利用上述方法,在模拟饮用水中检测到5种新的高分子量DBPs.在此基础上,通过同位素模式分析、TOF/TOF串联质谱和数据库验证,建立了针对未知高分子量DBPs的分子式/结构式识别方法,确定新的高分子量DBPs为寡糖羧酸类物质.

Disinfection is an important step in drinking water treatment process.However,disinfectants such as chlorine or chloramine can generate numerous halogenated disinfection byproducts(DBPs)with carcinogenicity,teratogenicity,and mutagenicity,which pose great threat to drinking water safety.More than 700 DBPs have been detected and identified in drinking water by researchers.The molecular weights of these known DBPs are all below 800 Da,and the understanding of high-molecular-weight DBPs is very limited.In this study,a detection method for high-molecular-weight DBPs was established based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS).It was found that when the matrix was 2,5-dihydroxybenzoic acid,the cationization agent was sodium trifluoroacetate,the sandwich deposition method was used,the reflection-positive ion mode was applied,and the laser intensity was 90%,the highest signal intensity of high-molecular-weight DBPs could be obtained.At such condition,the signal reproducibility was maximized,the sum of the signal-to-noise ratio of new high-molecular-weight DBPs reached 136.2,and the coefficient of variation(CV)was 4.77%.Five new high-molecular-weight DBPs were detected in simulated drinking water using the above method.On such basis,a formula/structure identification method for unknown high-molecular-weight DBPs was established by isotopic pattern analysis,TOF/TOF tandem mass spectrometry,and database verification.With this method,the five new high-molecular-weight DBPs were determined to be oligosaccharide carboxylic acids.