Peak resolution by semiderivative voltammetry

Abstract

One of the limitations of dynamic electrochemistry, when used as a quantitative analytical technique, is the resolution of overlapping waves, Approaches used in the past have been either time intensive methods using many blanks, or have relied on many empirical peak parameters, Using an approach based on semidifferential voltammetry, two new techniques have been developed for rapid peak deconvolution. The first. NIFITl, is an iterative stripping routine, while the second, BIMFIT, is based on sequential simplex optimization. Both approaches were characterized by deconvolution of synthetic fused peak systems. subsequently, both WE!re applied to semidifferentited linear scan voltammograms of Cd{sup 2+} , Pb{sup 2+} and In{sup 3+} and to semidifferentiated linear scan anodic stripping voltammograms of Cd{sup 2+} , ln{sup 3+} and Tl{sup +}. Deconvolutions were directly characterized by peak height, peak potential and peak halfwidth, as well as by the total squared deviation of the fit peaks from the real fused peaks. Studies of individual peaks as well as of standard additions to fused peaks showed both methods worked well, with excellent deconvolution efficiencies. Synthetic data were totally deconvoluted with peak separation as small as 25 mv, while real systems were deconvoluted with separations below 40 mv. Peak parameters obtained from these deconvolutions allow observations of electrode processes, even in systems containing overlapping peaks.