Target transform fitting in a voltammetric study of metal complexation.

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Computational Chemistry

Background:

• Differential pulse polarography is a sensitive electrochemical technique.
• Analyzing successive metal complexation systems requires robust data analysis methods.
• Existing methods may struggle with the presence of unknown species.

Purpose of the Study:

• To propose and validate Target Transform Fitting (TTF) as a hard-model based method for analyzing differential pulse polarograms in successive metal complexation.
• To accurately estimate stability constants, E(1/2) values, and diffusion coefficients.
• To assess the method's reliability in the presence of unknown species.

Main Methods:

• Utilized Target Transform Fitting (TTF) with pre-defined models for complexation equilibria and polarogram shapes.
• Employed a two-stage fitting process: first, estimating E(1/2) values; second, determining overall formation constants using non-linear fitting.
• Applied the Rank Annihilation (RA) method for diffusion coefficient calculations.

Main Results:

• Successfully estimated stability constants and E(1/2) values for species in a successive complexation system.
• Demonstrated accurate analysis even when unknown species were present in the data.
• Validated the method using simulated data and experimental polarograms of Cd(II) and 1,10-phenanthroline.

Conclusions:

• Target Transform Fitting (TTF) provides a reliable and accurate hard-model approach for analyzing complex electrochemical data from successive metal complexation.
• The method's robustness allows for correct analysis despite the presence of unanticipated species.
• TTF offers a valuable tool for electrochemical data analysis in complex chemical systems.