The effect of surfactant micelles on the dissociation constants and transition points and transition intervals of acid–base indicators

The effects of cetyltrimethylammonium (CTAB), sodiumdodecylsulfate (SDS) and pol(oxyethylene)(9.5)p-(1,1,3,3-tetramethyl; Triton X-100) on the dissociation constants, transition points and transition intervals of thymol blue and bromothymol blue were studied. The experimental results indicated that surfactant micelles remarkably affected dissociation constants, transition points and transition intervals of the acid–base indicators, and the application ranges of acid–base indicators became wider and the titration accuracy increased when an appropriate surfactant micellar solution was chosen as a titration medium.