Determination of acidity constants of acid-base indicators by second-derivative spectrophotometry

A method for calculation of acid-base dissociation constants of monoprotic weak organic acids whose acid and base species have overlapping spectra fro m absorptiometric and pH measurements is described. It has been shown that the second-derivative spectrophotometry can effectively be used for determi ning the dissociation constants, when dissociation constants obtained for m ethyl orange and bromothymol blue were compared with the values given in th e literature. (C) 2000 Elsevier Science B.V. All rights reserved.