摘要:
近年来,以氨基酸为前体物的含氮氯代消毒副产物成为饮用水安全保障研究领域的热点问题,其中氯代亚胺是具有嗅味特征的含氮消毒副产物,化学结构为 R-CH=NCl。本研究基于气相色谱-质谱(GC/MS)法和高效液相色谱-质谱(HPLC/MS)法,鉴定识别了源于苯丙氨酸(phenylalanine,Phe)等氯代亚胺类消毒副产物；通过 GC/MS 谱图对其他未知消毒副产物进行定性分析,解析了苯丙氨酸氯消毒过程的转化规律。结果表明：在氯化过程中,缬氨酸(valine,Val)可生成异丙基氯代亚胺(isobutyrochloraldi-mine)副产物；苯丙氨酸可生成氯代苯乙亚胺(chlorophenylacetaldimine)、苯乙醛(phenylacetaldehyde)和二苯基吡啶(2,6-diphenylpyridine)等副产物；其反应途径为 Phe 与氯反应进行一氯取代和二氯取代生成氯代Phe 和二氯代 Phe,二氯代 Phe 能分解生成氯代苯乙亚胺类物质。采用液液萃取-HPLC 分离提纯氯代苯乙亚胺,以 GC/MS 定量分析饮用水中氯代亚胺类消毒副产物的含量水平。结果发现,在某城市4座水厂的出厂水中均检出氯代苯乙亚胺,浓度为5.03~11.26μg/L。这说明原水中存在氨基酸类溶解性有机氮时,消毒过程会产生氯代亚胺类消毒副产物,导致饮用水存在此类消毒副产物的污染风险。
Abstract:
Nitrogenous disinfection byproducts (N-DBP)in drinking water attract more and more attention,among which chloraldimines are one kind of off-flavor N-DBP gen-erated from different kinds of amino acids,posing the general chemical structure as R-CH=NCl.Based on GC/MS and HPLC/MS,chloroaldmines originated from valine and phenylalanine were identified.The other unknown by-products of phenylalanine were identified by GC/MS and the transformation pathway of phenylalanine was pro-posed.The results show that chlorination of valine (Val)can induce isobutyrochloraldi-mine,while phenylalanine (Phe)can induce chlorophenylacetaldimine,phenylacetalde-hyde and 2,6-diphenylpyridine.Phe reacts with chlorine to produce chlorophenylalanine and dichlorophenylalanine,which can decompose and transform to phenylacetaldehyde. Dichlorophenylalanine can also produce N-chlorophenylacetaldimine. HPLC coupled with liquid-liquid extraction was emplyed to purify chlorophenylacetaldimine, and GC/MS was used to determine the concentration.Occurrence of chlorophenylacetaldi-mine was measured,and the concentration ranged from 5.03-1 1.26 μg/L in four drink-ing water treatment plants of a certain city.Results show that the contamination risk of chloroaldmine exists in drinking water.
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