A program for the simultaneous potentiometric determination of protonation constants and electrode calibration parameters

Résumé fourni par la source

A program for the potentiometric determination of the protonation constants of mononuclear polyprotic substances is described. A maximum of twelve parameters can be determined simultaneously, including up to six protonation constants, four electrode calibration parameters, the protolysis constant of the solvent and the titrant concentration. Optimization is carried out by using the non-simplified Newton-Raphson method, which is potentiated by the Marquardt algorithm and a distance speeding-up coefficient. A direct search method is also used to improve the initial set of values. Variances are calculated very accurately, since the real Hessian function is used. Statistical weights and ionic strength corrections are also considered. The program has been tested by using simulated titration curves of polyprotic acids with close constants.

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