Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The formation of ionic associates of atropine and quinine with bromothymol blue, metanil yellow and cresol red was studied by extraction spectrophotometry. In aqueous solutions, formation of ionic associates was only observed for quinine with bromothymol blue; ionic associates of both dyes with all of the three dyes could be, however, studied by their extraction into chloroform. The conditional extraction constants were calculated for the equilibria involved. The ability of atropine, quinine and bromothymol blue to be extracted into chloroform was examined in dependence on pH and ionic strength of the aqueous phase. The pH_1/2 value corresponding to 50% extraction recovery decreases with increasing ionic strength for quinine whereas for atropine the extraction recovery is only slightly affected by a higher ionic strength and for bromothymol blue the pH_1/2 (E = 50%) value increases with increasing ionic strength.