ADSORPTIVE STRIPPING VOLTAMMETRY OF TRACE THALLIUM

A highly selective and sensitive adsorptive stripping voltammetric procedure for trace measurements of thallium in presence of o-cresolphthalein (OCP) is described. The response is not affected by the presence of excess tin, lead or indium, which can interfere severely in analogous anodic stripping measurements. The adsorptive strategy also offers enhanced sensitivity over anodic stripping measurements. The detection limit is 60 ng/l (3 x 10(-10) M) with 2-min accumulation, and the relative standard deviation (at the 5 mug/l level) is 3.6%. Optimal conditions were found to be 0.01 M sodium hydroxide containing 5 X 10(-7) M OCP, a preconcentration potential of -0.30 V and a differential pulse waveform.