TRIPLE-PULSE VOLTAMMETRY AND POLAROGRAPHY

The faradaic response of a slow electron transfer to a triple pulse of potentials was derived for the planar approximations of a static mercury drop electrode and the dropping mercury electrode. The analytical solution obtained for a static mercury drop electrode is subject to no constraints in the time interval over which the different potentials are applied. The effects of the formation of the double layer have not been taken into account in the mathematical treatment. The solution obtained was verified by comparising of the analytical solution to experimentally measured l-t curves for some completely reversible, completely irreversible, and quasi-reversible processes, namely the reduction of Cd(II), Cr(III), and Zn(II), respectively. The use of a triple pulse of potentials to develop new voltametric and polarographic techniques, improving on the performance of double-pulse techniques, is discussed. Among these we propose the double differential pulse (DDP) technique which involves using the current function l1 - 2l2 + l3 where l(j) is the current corresponding to potential pulse E(j). We also propose the square well pulse (SWP) technique which relies on the current function l3 + l2 - 2l1 for a time ratio t2/t3 = 0.283. Finally, the solution for the previously reported reverse differential normal pulse (RDNP) technique was obtained. The features and performance of these techniques are discussed.