A simple method for calculating acidity parameters, suggested in a previous
publication (React. Funct. Polym. 38 (1998) 73), as well as constants for
the modified Henderson-Hasselbach equation, is described. It follows from a
nalysis of the shape of potentiometric titration curves of ion exchangers t
hat along with the vertical inflection at the equivalence point, they have
a horizontal inflection at half neutralization. The pH value and the tangen
t of the titration curve at that point are simply related to the acidity pa
rameters of resins. The derived equations allow ready determination directl
y from the titration curve. (C) 2000 Elsevier Science B.V. All rights reser
ved.