Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Based on computer-assisted calculations, six screened indicators were prepared and used for visual titration end point indication. Three of them were evaluated in terms of objective colour characteristics. Their colour changes were characterized in the CIE-xy (1931) international colorimetric system, by the Helmholtz coordinates, complementary Q_x, Q_y coordinates, perceptibility and course of the ΔJ/ΔpH = f(pH) function. In addition, new indices were introduced, viz. partial quality indices I_E, I_p and I_m, related with the colour difference between the two indicator species (I_E), their colour purity (I_p) and the experimenter's ability to remember the colour in the titration end point (I_m). Summed up, the three indices constitute the total quality index of the chemical indicator I_t. These indices were employed for comparing the single and the corresponding screened indicators.