Theoretical and experimental resolution of semi-derivative linear scan voltammetry

New procedures, based on the transformation of voltammetric current by semi -differentiation, have been proposed to improve resolution in linear scan v oltammetry (LSV). For a reversible charge transfer, the obtained shape of t he current semi-derivative is fully symmetrical and even in the case of an irreversible electrode reaction it is considerably more symmetrical compare d with the original LSV signal. To evaluate and compare the resolution of s emi-derivative linear scan voltammetry (SDLSV) with other techniques, theor etical calculations were performed to determine the qualitative resolution as well as the quantitative resolution defined in our previous work. The fo llowing quantities have been calculated: (i) the minimal difference in the peak potentials of two depolarisers, necessary to obtain two distinct peaks on an SDLSV record, (ii) the difference in the peak potentials enabling th e determination of the depolarisers with only a 1% systematic error, due to overlapping. Verification of the developed theory was performed experiment ally using a set of solutions containing two electroactive components in 1 M HCl: Pb(II)-TI(I), Pb(II)-In(III), Pb(II)-Cd(II), TI(I)-In(III), TI(I)-Cd (II), and In(III)-Cd(II). The proposed mathematical approach and experiment al procedures enable a simultaneous SDLSV determination of two or even more depolarisers with a minimal error.