Polarographic current–voltage curves of fluorescein. Part I. Effect of pressure-head of mercury on mean current

Abstract

It has been shown, from a study of polarograms and of the effect of pressure-head of mercury on mean current, that in alkaline solutions fluorescein undergoes reduction at the dropping-mercury electrode in two steps; the first polarographic wave is entirely diffusion-controlled, and the second is an irreversible one, each being a one-electron process. In the acidic range, a single-step irreversible reduction occurs, which has been proved to be due to competition of kinetics with diffusion. In strong acids, however, mean currents over the single polarographic wave depend approximately on the square-root of the mercury pressure, as for a reversible wave. A new method is thus available, instead of the more sophisticated techniques, to determine the nature of polarographic current–voltage curves.