酸分解-中和滴定法による粒状洗剤中の炭酸塩の定量

概要

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A simple and rapid method for the determination of carbonate was developed. A carbonate sample was decomposed in a hydrochloric acid solution and the evolved carbon dioxide was absorbed in a barium hydroxide solution. The absorption was carried out with apparatus consisting of two gas washing bottles with a circulating air pump (Fig.-1). The air pump was operated for 5min to fix carbon dioxide completely in the barium hydroxide solution to form BaCO<SUB>3</SUB>. Finally, the excess barium hydroxide was titrated with a standard solution of 1N hydrochloric acid using phenolphthalein as an indicator. Removal of precipitated barium carbonate during titration was unnecessary. The determination required about 10min per sample with a recovery of more than 99% and a coefficient of variation within 0.5%.<BR>The proposed method was applied to the determination of sodium carbonate in various commercial granulate detergents. The results were compared with those from an autoanalyzer method. Good agreement was obtained with both methods, thus concluding the content of sodium carbonate in a granulated detergent can be determined more conveniently by the proposed method.
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