五步碘量法测定消毒剂中二氧化氯的方法改进

IMPROVEMENT OF FIVE-STEP IODOMETRY FOR MEASURING CHLORINE DIOXIDE IN DISINFECTANT

目的改进五步碘量法对二氧化氯测定方法,以便更准确地检测消毒剂中二氧化氯含量。方法采用调整测定试液pH值和延长吹氮气时间的措施进行了实际样品检测。结果改进五步碘量法测定中,样品溶液中氧化性物质的总浓度在1000-3000mg/L,取样量为2-5ml为佳。测定不同样品需要将磷酸盐缓冲溶液pH值调节到7.0,pH值随缓冲液加入量的变化而变化,达到一定量后pH值趋于稳定。同一种二氧化氯样品的不同次取样,吹氮时将样品溶液吹至无色,测得二氧化氯含量存在差别;吹至无色后再继续吹不同时间,测得二氧化氯量基本一致,在吹至无色后,再继续吹30min即可。结论在改进五步碘量法操作中,采用控制样品液氧化物总浓度,适当调整试液酸碱度和延长吹氮气时间,可保证二氧化氯测定浓度准确性。

Objective To improve five-step iodometry method for measuring chlorine dioxide in order to measure chlorine dioxide in disinfectants more accurately.Methods Measures of regulating pH value of the test solution to be measured and prolonging time of blowing nitrogen gas were used to carry out measurement of actual sample.Results In measurement with improving five-step iodometry method,it was optimal that the total concentration of the oxides in the sample solution was 1000-3000 mg/L and the sample volume was 2-5 ml.For measuring different samples,it was necessary to adjust the pH value of phosphate buffer solution to 7.0.The pH value was changed with change in amount of the buffer solution added and became stable after adding certain amount.For different samples taken from the same chlorine dioxide sample,the chlorine dioxide contents measured were different if the nitrogen gas was blown till the sample solution became colorless,while the chlorine dioxide contents measured were essentially identical if the nitrogen was blown further for a different periods of time after the sample solution became colorless.Blowing for additional 30 min after the sample solution became colorless was adequate.Conclusions In the operation of improving five-step iodometry,controlling the total concentration of oxides in sample solution,adjusting pH value of the test solution and prolonging the time of blowing nitrogen can ensure the accuracy of measurement of chlorine dioxide concentration.