全自动电位滴定法测定水中氯化物

Determination of Chloride in Water by Automatic Potentiometric Titration Method

为了实现快速准确测定水中氯化物含量,建立了一种全自动电位滴定法测定水中氯化物的分析方法,对取样体积进行了优化,研究了CO_(3)^(2-)、S^(2-)、I^(-)、Br^(-)等对氯化物测定结果的影响,并就干扰离子的消除提出了有效的方法,结果表明,最佳取样体积为50 mL,水样中加入1 mL硝酸溶液(2+98)可消除S^(2-)、CO_(3)^(2-)的干扰,当水样中I^(-)、Br^(-)浓度高于5 mg/L时仪器可自动校正并扣除干扰。方法的检出限为0.19 mg/L,大大低于国家标准GB/T 11896—1989中规定的10 mg/L的要求,方法用于测定地表水、地下水和工业废水实际样品,精密度为1.9%~2.3%,加标回收率为91.9%~99.0%。采用全自动电位滴定法测定水中氯化物检出限低、精密度和正确度良好。方法的建立为复杂环境水样中氯化物的准确测定提供了有益的技术支撑。

In order to achieve rapid and accurate determination of chloride content in water,a fully automatic potentiometric titration method for the determination of chloride in water was established.The sampling volume was optimized,and the effects of CO_(3)^(2-),S^(2-),I^(-),Br^(-),etc.on the chloride determination results were studied.Furthermore,an effective method for eliminating interfering ions was proposed.The results showed that the optimal sampling volume of this method was 50 mL.The interference of S^(2-),CO_(3)^(2-)can be eliminated by adding 1 mL(2+98)nitric acid solution to the water sample.When the concentration of I^(-)and Br^(-)in the water sample higher than 5 mg/L,the instrument can automatically correct and deduct the interference.The detection limit of this method was 0.19 mg/L,which was much lower than the requirement of 10 mg/L specified in the national standard GB/T 11896—1989.The method used to determine actual samples of surface water,groundwater,and industrial wastewater,with a precision of 1.9%-2.3%,and corresponding spiked recovery rate of 91.9%-99.0%.The fully automatic potentiometric titration method was used to determine chloride in water with low detection limit,good precision and accuracy.The establishment of the method provided a useful technical support for the accurate determination of chloride in complex environmental water samples.