指示薬の変色率をパラメータとするアミノピリンの滴定法

Abstract

Concentration of compound AB can be determined by acid base titration from Eq. 1. CAB=[CH-{(KaIND·((1-φ))/φ)+CIND·(1-φ)}]·(1+KaAB/KaIND·φ/((1-φ))) (1) CAB : molar concentration of AB, CIND : molar concentration of indicator, CH : hydrogen concentration of the solution, KaAB : acid dissociation constant of AB, KaIND : acid dissociation constant of indicator, φ : color transition ratio of indicator. In Eq. 1 value of φ can be measured by complementary tristimulus colorimetry (CTS method). Values of CH, CIND, KaAB and KaIND are determined by using an appropriate kind of method before the titration. AB can be determined by setting the values of parameter to the Eq. 1. By this principle aminopyrine (2.2-2.85g) could be determined by adding a prescribed amount of 0.5 N HCl standard solution in ±2% and by using bromphenol blue as a indicator.