Girenko Dmitry V, Gyrenko Al'ona A, Nikolenko Nikolai V
Ukrainian State University of Chemical Technology, Gagarin ave. 8, 49005 Dnepropetrovsk, Ukraine.
Int J Anal Chem. 2019 May 2;2019:2360420. doi: 10.1155/2019/2360420. eCollection 2019.
The method of iodometric determination of chlorates impurities in sodium hypochlorite solutions for medical and veterinary purposes was developed. This method does not require sophisticated equipment and can be implemented directly where the solutions are used. The method is based on the different rates of interaction of ClO and ClO with iodide ions depending on the acidity of the medium. We have shown that blank titration is advisable to improve the accuracy of the determination of low concentrations of chlorates in the matrix of hypochlorite which is present in excess since in this case possible systematic errors due to the presence of oxidizing impurities in the reagents are prevented. To quantify the low concentrations of chlorates, we proposed to remove 85-95% of hypochlorite ions by means of reducing their excess with sodium sulfite at pH 10.5. The solution of sodium sulfite does not require standardization before each analysis in the proposed procedure. The possibility of quantitative determination of chlorate impurities in the range of 2-50 mg/L in the presence of 50-500-fold excess of sodium hypochlorite with an error of 5% has been proved. The expanded uncertainty of chlorate determination did not exceed 0.6 mg/L.
开发了用于医学和兽医学目的的次氯酸钠溶液中氯酸盐杂质的碘量法测定方法。该方法不需要复杂的设备，并且可以在溶液使用地点直接实施。该方法基于ClO和ClO与碘离子的相互作用速率因介质酸度而异。我们已经表明，对于存在过量次氯酸盐基质中低浓度氯酸盐的测定，建议进行空白滴定以提高准确性，因为在这种情况下可以防止由于试剂中存在氧化性杂质而可能产生的系统误差。为了定量低浓度的氯酸盐，我们建议在pH 10.5下用亚硫酸钠还原过量的次氯酸盐离子，以去除85-95%的次氯酸盐离子。在所提出的程序中，每次分析前亚硫酸钠溶液不需要标准化。已证明在存在50-500倍过量次氯酸钠的情况下，能够定量测定2-50 mg/L范围内的氯酸盐杂质，误差为5%。氯酸盐测定的扩展不确定度不超过0.6 mg/L。
