Differential-pulse voltammetric determination of phosphate as molybdovanadophosphate at a glassy carbon electrode and assessment of eluents for the flow injection voltammetric determination of phosphate, silicate, arsenate and germanate

Abstract

The redox behaviour of molybdovanadophosphate at a glassy carbon electrode is described and a procedure is given for the voltammetric determination of phosphate as molybdovanadophosphate at a glassy carbon electrode in a static system. Procedures are also given for the voltammetric flow injection determination of phosphate, silicate, arsenate and germanate by the injection of heteropolyacids pre-formed in various aqueous, aqueous acetone and aqueous ethanolic reagents into eluents consisting of the reagent blank. This procedure effectively eliminates the background signal of the blank and allows precise determinations to be made. Plots of electrode potential against the current obtained are given.

Silicate and phosphate can be determined at 10^–7 and 10^–6M levels, respectively. Arsenate has only been determined at the 10^–5M level, and the precise determination of germanate is difficult owing to adsorption at the glassy carbon electrode.