α-ナフトールベンゼインを指示薬とした非水滴定への簡易化コンプリメンタリートリスティミュラス法の応用

概要

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In non-aqueous titration, some indicators have no simple color change but pass successively through a wide range of the color shades. Dull color change of the indicator introduces a large indicator error at the end point of the titration. To ensure accuracy, the chemical stoichiometric relationship between color transition of the indicator and the equivalence point was considered. The color transition of the indicator was calculated by simplified complementary tristimulus colorimetry (simplified CTS method) in which the steps for reading absorbance in the three ranges of absorption spectra were simplified. The calculation of the color transition made us possible to derive the theoretical equation for the determination without indicator error. In a visual titration by using an indicator, the color shade at the end point of non-aqueous titration had been decided empirically without theoretical treatise. Then by using the simplified CTS method, the color shade at the equivalence point of the titration could be known previously from the theoretical relationship between the titration ratio and the concentration of free titrant. As a typical example of these sujects, 3 ml of 10^<-2>M glycine was titrated with α-naphtholbenzein as an indicator and perchloric acid as a titrant in anhydrous acetic acid. (Recovery : 97.3%)
社団法人日本薬学会の論文
1982-05-25