Stripping voltammetry with adsorptive accumulation for trace measurements of titanium

Abstract

A sensitive stripping voltammetric procedure for determining titanium is described. The chelates of titanium with various dihydroxyazo dyes are adsorbed on the hanging mercury drop electrode, and the reduction current of the accumulated chelate is measured by voltammetry. Cyclic voltammetry is used to characterize the redox and interfacial processes. Optimal experimental conditions were found to be a stirred acetate buffer (pH 5.1) solution containing 1.5 × 10 −6 M solochrome violet RS, a preconcentration potential of −0.42 V, and a linear scan stripping mode. The chelate peak is separated from that of the free dye by 110 mV. There is a linear relationship between the preconcentration time and peak height at low surface coverages. With a 5 min preconcentration period the detection limit is 7 × 10 −10 M (0.035 ppb). Linearity prevails using short preconcentration times. The relative standard deviation at 1 × 10 −7 M is 3.4%. The possible interferences by other trance metals are investigated. Simultaneous determination of titanium(IV) and Fe(III) is illustrated. The merits of the described procedure are demonstrated in the analysis of sea, river and rain waters.