HIGHLY SENSITIVE AND SELECTIVE MEASUREMENTS OF LEAD BY STRIPPING VOLTAMMETRY POTENTIOMETRY FOLLOWING ADSORPTIVE ACCUMULATION OF THE LEAD-O-CRESOLPHTHALEXON COMPLEX

A very sensitive and selective stripping procedure for trace measurements of lead, based on the adsorptive accumulation of the lead-o-cresolphthalexon (OCP) complex onto various mercury electrodes is described. The technique offers enhanced sensitivity over analogous stripping measurements of lead (with a detection limit of 40 ng 1(-1) after 2 min accumulation). Even more significant is the improved selectivity in the presence of a large excess of thallium or tin (which commonly interfere in anodic stripping measurements). Both voltammetric and potentiometric stripping modes can be employed to probe the reduction of the lead-OCP complex. The reported coupling of the new method with disposable screen-printed electrodes holds a great promise for decentralized testing of lead. Applicability to assays of drinking water is illustrated.