Rapid adsorptive cathodic stripping voltammetry of zinc complexes in sea water

Abstract

The effects of the potential scan speed on the adsorptive cathodic stripping voltammetric determination of zinc-tetramethylenedithiocarbamate complexes in sea water were investigated. It was observed that an increase in scan speed increases the peak height and peak width, shifts the peak potential towards negative values and increases the capacitance background current. These effects were explained by taking into account the ohmic drop at high scan speeds. Several advantages of using a high scan speed in the determination of zinc were found. The faradaic current and sensitivity of the determination are noticeably increased as the whole electroactive substance is reduced in a shorter time. The stirring or turbulent motion of the solution during the scan does not perturb the zinc peak as the complete scan is done in a few milliseconds. Oxygen interference is less severe as the metal and oxygen reduction currents are now in the same current range. The entire analysis time can be markedly reduced as the purging, collection and quiescence time can be decreased. The method is proposed for use on-board oceanographic vessels where its advantages are especially valuable. All results were obtained using a laboratory-designed polarograph able to operate at very high scan speeds.