Catalytic Adsorptive Stripping Voltammetric Determination of Germanium Employing the Oxidizing Properties of V(IV)-HEDTA Complex and Bismuth-Modified Carbon-Based Electrodes.

An efficient procedure that may be used to determine germanium traces and combines the advantages of catalytic adsorptive stripping voltammetry (CAdSV) with the convenience of screen-printed electrodes was developed. To induce the CAdSV response of the germanium(IV)-catechol complex, the vanadium(IV)-HEDTA compound was employed in combination with various bismuth-modified homogeneous (glassy carbon, gold coated with a bismuth layer via physical vapor deposition) and heterogeneous (screen-printed carbon, mesoporous carbon, graphene and reduced graphene oxide, polymer-encapsuled carbon fiber) electrodes. This solution had never before been implemented for this purpose. To achieve the most favorable performance of the working electrode, the parameters of bismuth deposition were optimized using a central composite design methodology. SEM imaging and contact angle measurements confirmed the long-term stability and high chemical resistance of the electrodes against the oxidizing action of V(IV)-HEDTA. Under optimized conditions, the method made it possible to detect nanomolar concentrations of germanium with favorable detection limits, high sensitivity, and a wide linear range of 5-90 nM of Ge(IV).

Review of the catalytic voltammetric determination of titanium traces.

Catalytic and catalytic adsorptive stripping voltammetry are some of the most sensitive analytical methods. A review of various catalytic and catalytic adsorptive systems of titanium and their use in voltammetric analysis is presented. The mechanisms of catalytic reactions are discussed in detail. In addition to a survey of literature (91 references), catalytic polarographic, voltammetric and catalytic adsorptive stripping voltammetric determination of titanium traces at liquid mercury and metallic films electrodes are discussed briefly. Moreover, the application of the redox systems Ti(IV)/Ti(III) for the indirect determination of voltammetrically inactive oxidizers participating in catalytic reactions (e.g. chlorates) and voltammetrically inactive ligands (e.g. organic acids and thiocyanates) is also presented.