Abstract： Based on precipitation reaction of barium and sulfate radical, rhodizonic acid disodium salt was discolored by excess barium, the method ofdetermining sulfate radical by barium chloride titration withrhodizonic acid disodium salt test paper as indicator has been established. The filter paper was dipped in rhodizonic acid disodium salt mixing solution,rhodizonic acid disodium salt test paper can be used as the external indicator for the determination of sulfate radical. The effect of test paper production, acidity and coexisting ion influence were discussed and investigated. The result shows that：the filter paper will be dipped in rhodizonic acid disodium salt solution, sodium acetate solution will be joined together to soak , and then test paper will be separated from each other at 110 ℃ or so in the dark, which can be dried rapidly. The dried test paper has better performance in coloring, the stability has been improved notably. In the medium of pH 4-6,test paper discolored sensitively and responsed rapidly, the determination will not be interfered by the most common ions . This method was used in the water sample analysis,compared with gravimetric method, the measured value was consistent , and the relative standard deviation (RSD, n=7) of the method were between 0.30%-0.42%.
董亦斌. 玫瑰红酸钠试纸作外指示剂-氯化钡滴定法测定水中硫酸根[J]. 冶金分析, 2013, 33(4): 61-63.
DONG Yi-bin. Determination of sulfate radical in water by barium chloride titration with sodium rhodizonate test paper as external indicator. , 2013, 33(4): 61-63.
