透析用水中游离氯与氯胺的测定

Detection of chlorine and chloramines in dialysis water

目的透析用水中游离氯和氯胺浓度超标会对人体造成巨大危害,而我国目前大多数透析中心只能检测游离氯,本研究通过检测自来水和透析用水中游离氯和氯胺含量,评估了单独检测游离氯的安全性,并评估了目前常用的TMB目视比色法的准确性。方法以DPD分光光度法为金标准,同时采用DPD分光光度法和TMB目视比色法对北京市9家透析中心的自来水和透析用水中游离氯和氯胺浓度进行检测,每家血液透析中心检测2d,每天检测10次,每次间隔1h;对透析用水中游离氯和氯胺浓度进行相关性分析,P<0.05认为有统计学意义;对DPD分光光度法和TMB目视比色法的检测结果进行Kappa检验。结果在各个时点,各透析中心的透析用水中游离氯和氯胺浓度均在国家标准范围之内;透析用水中游离氯和氯胺浓度之间不存在线性相关关系(r=0.14,P=0.146);同DPD分光光度法相比,TMB目视比色法所测得游离氯结果的假阴性率为100%,kappa值为0,所测总氯结果的假阴性率10.67%,kappa值为0.88。结论单独检测游离氯是不安全的,必须同时检测总氯浓度;同DPD分光光度法相比,TMB目视比色法测得的游离氯和总氯结果存在一定的假阴性率,建议有条件的单位尽量采用DPD分光光度法。

Objective Exceeding chlorine and chloramines in dialysis water is harmful to human body, but most dialysis centers in China can only measure chlorine content. The aim of the current study was to evaluate the safety only based on chlorine content, as well as the accuracy of TMB visual colorimetry. Methods Levels of chlorine and chloramines in dialysis water and tap water were measured using both TMB visual colorimetry and DPD spectrophotometry, and values from DPD spectrophotometric method were used as the golden standards. Dialysis water and tap water from 9 dialysis centers were assayed every hour and ten times per day for two days. Linear regression was used to explore the relationship between chlorine and chloramines in dialysis water, and P 0.05 was considered statistically significant. Kappa test was used to compare the difference between the values from DPD spectrophotometry and those from TMB visual colorimetry. Results Concentrations of chlorine and chloramines in dialysis water were below the standards recommended by AAMI at every time point. There was no linear relationship between chlorine and chloramines contents in dialysis water （r =0.14, P =0.1460）. TMB visual colorimetry gave a false negative rate of 100% with kappa=0 for free chlorine measurement, and a false negative rate of 10.67% with kappa=0.88 for total chlorine measurement as compared with the values from DPD spectrophotometry, Conclusion For dialysis water, monitoring free chlorine alone is probably unsafe, and chloramines or total chlorine should also be measured. Compared to DPD spectrophotometry, TMB visual colorimetry gives a remarkable false negative rate, suggesting the preferential use of DPD spectrophotometry method if possible.