饮用水中氯化物的氯离子选择电极测定法

Determination of Chloride in Drinking Water by Chloride Ion-Selective Electrode

目的建立一种简单、快捷、准确、实用的氯离子选择电极测定水中氯化物的方法。方法以氯离子选择电极为指示电极,双液接饱和甘汞电极为参比电极,应用标准曲线法直接测定水中氯化物。在0.1mol/LKNO3介质中,待电位平衡后,记录相应的电位值E(mV)。以标准溶液的E对-logc作曲线回归,根据样品的E值,由回归曲线求得Cl-的含量。结果方法的线性范围:10-5～100mol/L,最理想的范围为10-4～10-1mol/L,重复测定11次,斜率平均53.5,标准差0.667,平均相关系数0.9999,在含Cl-3.545mg/L的溶液中,50倍的BrO-3、NO-2、CH3COO-、SO42-、F-、CrO42-,10倍的CO32-不干扰;Br-、I-严重正干扰。回收率范围94.2%～102.2%,平均98.1%,变异系数2.8%,电极适宜的pH值范围2～10。电极法结果与国标法结果比较,经统计学处理,差异无显著意义。结论电极法的优点是操作简单,快速,不受色度干扰,准确,可用于水中氯化物的测定。

Objective To establish a simple,rapid,accurate and practical method for determination of chloride in drinking water by chloride ion-selective electrode.Methods The chlorine ion-selective electrode was used as indicator electrode and type217saturated calomel electrode of the double salt bridge(the lower salt bridge was filled with a solution of0.1mol/L potassium nitrate)was used as reference electrode.The contents of chloride in water were calculated using the calibration curve method in the electrolyte containing0.1mol/L potassium nitrate.Results The linear range of the method was10 -5 -10 0 mol/L and the best lin ear range was10 -4 -10 -1 mol/L with r=0.9999and the slope=53.5±0.667.The detection limit,recovery rate and coefficient of variation(CV)were0.3545mg /L,94.2%-102.2%(mean98.1%)and2.8%respectively.The suitable pH for the determination of the method was2-10.In the solution containing3.545mg/L chloride,50times more BrO -3 ,NO -2 ,CH 3 COO - ,SO 42- ,F - ,CrO 42- and10times more CO 32- could not interfere with the detection,but Br - and I - were interfering factors.The re-sults obtained by the chlorine ion-selective electrode method and the national standard determination method showed no statistic differences.Conclusion The method was easy to operate,rapid,accurate and suitable for determination of chloride in water.