Parametric Signal Fitting by Gaussian Peak Adjustment: implementation of 2D transversal constraints and its application for the determination of pKa and complexation constants by differential pulse voltammetry.

A new method, GPA2D, is presented as a significant improvement of the previously described Gaussian Peak Adjustment (GPA) which includes, for the first time, transversal constraints to increase the consistency of the resolution along the different signals of a voltammetric dataset. The constraints deal with the evolution of peak potentials versus pH and with the implementation of chemical equilibrium constants. Moreover, pkavolt, a new tool for the pKa determination, is proposed as an example of the great versatility of the PSF-GPA (Parametric Signal Fitting by Gaussian Peak Adjustment) methodology. GPA2D and pkavolt have been successfully tested on the systems Cd(ii):phytochelatin, Cu(ii):6-benzylaminopurine, Cd(ii):1,10-phenanthroline, Zn(ii):oxalate and captopril drug by determining formation constants (metal complex systems) or pKa values (captopril).