Catalytic Adsorptive Stripping Voltammetry of Germanium(IV) in the Presence of Gallic Acid and Vanadium(IV)‐EDTA

Abstract

A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)-gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)-EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO 4 (pH1.6), 6.0 Â 10 À3 mol/L GA, 3.0 Â 10 À3 mol/L V(IV), 4.0 Â 10 À3 mol/L EDTA, an accumulation potential of À 0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0 Â 10 À11 to 1.0 Â 10 À8 mol/L and the detection limit is 2 Â 10 À11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0 Â 10 À10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results.

Bismuth film electrode and chloranilic acid as a new alternative for simple, fast and sensitive Ge(iv) quantification by adsorptive stripping voltammetry

“…interferences also concern adsorptive voltammetric determination of germanium using as a working electrode the mercury electrodes 19,20 as well as BiFE as we have proved in this work. The measurements were performed by testing the inuence of different kinds of surfactants on the germanium signal, such as Triton X-100 (non-ionic), cetyltrimethylammonium bromide (CTAB-cationic), sodium dodecylsulfate (SDS-anionic), and rhamnolipid (biosurfactant), humic acids (HA), fulvic acids (FA), and natural organic matrix (NOM).…”

“…The major advantages of this method are simple and cheap apparatus featuring fast response and high sensitivity, affording adsorptive accumulation of the determined metal as a complex. In the literature several complexing agents for adsorptive accumulation of germanium were employed such as pyrogallol, 12 3,4-dihydroxybenzaldehyde (DHB), 13 pyrocatechol violet, 14 catechol, 15-18 gallic acid, 19 and recently chloranilic acid.…”

Selection of Optimal Ligand and Vanadium(IV) Complexonate for Sensitive Catalytic Adsorptive Stripping Voltammetric Quantification of Germanium

“…À [18], Ge(IV)-pyrogallol-BrO 3 À [19], Ge(IV)-o-catechol-V(IV) [20], and Ge-gallic acid in the presence of V(IV)-EDTA complex [21].…”

Determination of Total Germanium in Chinese Herbal Remedies by Square-Wave Catalytic Adsorptive Cathodic Stripping Voltammetry at an Improved Bismuth Film Electrode

“…Various analytical methods for determining the trace and ultratrace levels of germanium in medicine [4], food [5][6][7], water [8], and soil [5] have been reported, for example, inductively coupled plasma-mass spectrometry (ICP-MS) connected with solid phase extraction [4,8] and combination of hydride generation [9], graphite furnace atomic absorption spectroscopy (GF AAS) [6,10], the spectrophotometric method [11], the hydride generation atomic fluorescence spectrometry method [12], the luminol chemiluminescence flow method [13], and electrochemical methods [5,7,[14][15][16]. Among these methods, electrochemical methods show obvious advantages in accuracy, sensitivity, simplicity, low cost, and analytical speed [7].…”

“…Adsorptive stripping voltammetry (AdSV) is well suited to determine the trace metal elements. The AdSV procedures developed for the determination of germanium were based on the adsorptive accumulation of a germanium complex on the hanging mercury drop electrode (HMDE) [5,[14][15][16][17][18] or the mercury film electrode (MFE) [7]. Despite the advantages of mercury electrodes for stripping voltammetry, the toxicity of mercury or mercury salts could not be neglected since mercury causes risks to public health 2 International Journal of Electrochemistry and unavoidably contaminates the environment in practice.…”