丙二酸碘量法与改良五步碘量法测定二氧化氯含量的方法探讨

Discussion on the determination of chlorine dioxide content by malonic acid method and modified five step method

目的探讨国家标准测定方法在测定二氧化氯含量上遇到的难点和需要改进的建议。方法采用丙二酸碘量法测定样本,测定结果与改良五步碘量法测定的结果进行分析比较。结果改良五步碘量法在测定稳定二氧化氯溶液时,必须按产品说明书先活化样品后测定,测定结果为23 068.6 mg/L;丙二酸碘量法无需活化直接吸取样品测定,测定结果为24 309.0 mg/L。2种方法在测定二氧化氯固体释放剂二氧化氯释放量时,均需按产品说明书先活化样品后测定,均需另取一份样品通入高纯氮赶氯气和二氧化氯测定亚氯酸根含量,操作步骤繁琐。改良五步碘量法测定结果为2 222.0 mg/L,丙二酸碘量法测定结果为1 826.5 mg/L,结果偏低。结论在测定稳定二氧化氯溶液时,丙二酸碘量法无需活化直接吸取样品测定,操作简单,在实际运用时方便准确。在测定二氧化氯固体释放剂二氧化氯释放量时,丙二酸碘量法测定结果偏低,分析实验原理测定结果数据应除以0.8进行修正。

Objective To discuss the difficulties which the national standard met in the determination of chlorine dioxide content and propose suggestions for its modification. Methods The samples were measured by the method of malonic acid,and the results were compared with the results of the modified five step method. Results In the determination of stable chlorine dioxide solution,the modified five step method must be activated by the product specification and then determined. The result was23 068. 6 mg/L; while the malonic acid method needed no activation and performed direct absorption of samples for detection,and the result was 24 309. 0 mg/L. The tow methods,in determination of solid chlorine dioxide releasing agent release amount of chlorine dioxide,need to be performed according to the product specification,activation first and detection later,which both required to take another sample into high purity nitrogen and chlorine dioxide for the determination of chlorite content,so the operating steps are complicated. The result of modified five step method was 2 222. 0 mg/L,and the results of malonic acid was1 826. 5 mg/L,and the results were lower. Conclusion When determining stable chlorine dioxide solution,malonic acid iodometry needs no activation and performs direct absorbing samples for determination,so the method is simple,convenient and accurate in practical application. When determining the amount of chlorine dioxide released from solid chlorine dioxide,the determination result of malonic acid was low,and the results of the experiment should be divided by 0. 8.