酸碱滴定法测定天然石膏中的碳酸盐(无水碳酸)

建立了用溴百里酚蓝—酚红作指示剂,酸碱滴定法测定天然石膏中碳酸盐的方法。在确定了试验条件的基础上,对石膏国家一级标准物质GBW03109a和GBE03110分析,相对标准偏差分别为0.08%、1.05%;分析3个天然石膏样品,相对标准偏差分别为1.47%、1.67%和0.25%;对试样进行加标回收,回收率在95.53%～97.02%之间;方法检出限为0.15%。表明用该方法测试,结果准确可靠。

Determination of carbonate (anhydride carbonate) in natural gypsum by acid-base titration

The authors establish a method of acid-base titration to determine carbonate (anhydride carbonate) in natural gypsum, with bromothymol blue-phenol red as an indicator. National first-class standard substance of both GBW03109a and GBE03110 are determined, the relative standard deviation (RSD) is 0.08% and 1.05%, and three natural gypsum samples are also determined, the RSD is 1.47%,1.67% and 0.25%. Through recovery test of standard substance addition, the recovery rate is ranged from 95.53%~97.02%. Detection limit of the method is 0.15%. It is concluded that the determination results are satisfactory, exact and reliable.