饮用水中三氯乙醛含量的直接和间接测定方法比较分析  

A Comparison of Direct and Indirect Methods of Determination of Chloral in Drinking Water

作　　者：凌云飞 芮文武 桂萍[1] 郭风巧 邬晶晶 朱良琪 吴玲娟 张勇 LING Yunfei;RUI Wenwu;GUI Ping;GUO Fengqiao;WU Jingjing;ZHU Liangqi;WU Lingjuan;ZHANG Yong(China Academy of Urban Planning&Design,Beijing100044,China;Suzhou Planning&Design Research Institute Co.,Ltd.,Suzhou 215006,China)

机构地区：[1]中国城市规划设计研究院,北京100044 [2]苏州规划设计研究院股份有限公司,苏州215006

出　　处：《理化检验（化学分册）》2020年第11期1158-1162,共5页Physical Testing and Chemical Analysis(Part B:Chemical Analysis)

基　　金：饮用水全流程水质监测技术及标准化研究(2014ZX07402-001)。

摘　　要：为了减少超标结果的误判、降低检测频次,分别采用间接测定法吹扫捕集-气相色谱法(P&T-GC)和直接测定法液液萃取-气相色谱法(LLE-GC)对存在三氯乙醛含量超标情况(测定值大于国家标准GB 5749-2006规定的限值10μg·L^-1)的7个城市的35个出厂水和管网水样品进行了测定,并对产生这2种方法结果差异的原因进行了分析。方法验证结果显示,这2种方法均能满足质量控制要求,但P&T-GC的平行性优于LLE-GC的。这2种方法的测定结果显示:57.1%样品的P&T-GC测定结果大于10μg·L^-1,而LLE-GC的测定结果均小于规定的限值,t检验结果显示这2种方法存在显著性差异。分析原因发现,水中存在的三氯乙酸通过衍生化转化为三氯甲烷的生成能力越强,P&T-GC测得的三氯乙醛含量越高,而对LLE-GC的测定结果的影响不大;采样点与出厂水出水口的距离越远,P&T-GC和LLE-GC测得的三氯乙醛含量越高,但P&T-GC的增加幅度约为后者的5倍。因此,在采用P&T-GC测得实际水样中三氧乙醛含量超标时,建议采用LLE-GC进行复测和确认。In order to reduce the misjudgment of results out of specification and the frequency of detection,the indirect method of purge and trap-gas chromatography(P&T-GC)and the direct method of liquid-liquid extraction-gas chromatography(LLE-GC)were used for determination of 35finished water samples and pipe network water samples in 7cities with their determined results of chloral greater than limit(10μg·L-1)specified by national standard of GB 5749-2006,and the reasons for the difference between the results of these two methods were also analyzed.Results of method verification showed that both of two methods could meet the quality control requirements,but the parallelism of P&T-GC was better than that of LLE-GC.Determined results of these two methods showed that results of chloral in 57.1%of samples determined by P&T-GC were over 10μg·L-1,while results obtained by LLE-GC were less than the specified limit.The t-test results showed that a significant difference was found between the two methods,and the reasons for it were analyzed.As shown by results that the stronger the ability of trichloroacetic acid coexisting in water to be converted into trichloromethane by derivatization,the higher the content of chloral determined by P&T-GC,but this trend was not found in LLE-GC;the farther the distance between the sampling point and the outlet of the water plant was,the higher the content of chloral determined by P&T-GC and LLE-GC,but the increase of P&T-GC was about 5times than that of the latter.Therefore,LLE-GC was recommended to retest and confirm results out of specification of actual water sample determined by P&T-GC.

关 键 词：吹扫捕集-气相色谱法 液液萃取-气相色谱法 三氯乙醛 饮用水 方法比较 

分 类 号：O657.7[理学—分析化学]