Trace determination of germanium by means of adsorption waves in differential-pulse polarography

Abstract

An electrochemical technique for the detection of trace amounts of germanium was developed, in which germanium(1V) was adsorbed on a mercury electrode in the form of catechol complexes. The differentialpulse polarogram exhibited a well defined cathodic peak at -0.61 V versus Ag -AgCI. From normal-and reverse-pulse polarography, the peak was ascribed to the reduction of germaniumcatechol complexes adsorbed on the mercury electrode at a potential more positive than the peak potential. Electric charge evaluated from the cyclic voltammetric peak indicated that the complexes were adsorbed only sparsely on the electrode. Optimum conditions were 3.2 mmol dm-3 catechol, 0.7 mol dm-3 acetate buffer (pH 4.5), 0.1 mol dm-3 sodium perchlorate and -100 mV modulation amplitude. Foreign ions interfering with the detection were As111 and Sn". From a calibration graph of peak current in the differential-pulse mode, the contents of germanium in aluminiumgermanium alloys were determined as an application of this technique.

Adsorptive Stripping Voltammetric Determination of Germanium in Zinc Plant Electrolyte

“…An important criterion for ligands to be suitable for the adsorptive stripping voltammetric determination of germanium appears to be the presence of at least two hydroxy groups which are at positions ortho to each other as occurs in catechol (2,3-dihydroxybenzene) [7], 1,2,3,-trihydroxybenzene [8] and epinepherine (3,4-dihydroxy-a-(methylaminomethyl) benzyl alchohol) [9]. These hydroxy sites are used to complex germanium prior to adsorption of the metal complex onto the HMDE.…”

“…Figure 1 shows the structure of the 6 ligands examined in this study. Catechol and pyrogallol have been used by other authors [7,8] while four new ligands alizarin red, pyrocatechol violet, fluorone black and quercetin are considered in our work. The suitability of ligand in the context of the present work is based on its ability to give a welldefined adsorptive stripping voltammetric signal, which is not interfered by other metal ions such as cadmium and zinc ions, present in the zinc plant electrolyte.…”

“…However, DPASV is limited to certain elements in Groups Ib, IIb, IIIb, IVb and Vb of the periodic table. Whilst the irreversible electrochemical characteristics associated with reduction of germanium(IV) [6] has usually made DPASV unsuitable for determining trace concentration of this element, recent publications have shown that germanium can be determined accurately down to sub parts per billion levels after complexation with catechol, pyrogallol and adrenalin [7][8][9] and using differential pulse adsorptive stripping voltammetry (DPAdSV). These determinations have been made on vegetable, metal alloy and ore samples.…”

Direct Voltammetric Specific Recognition of Dopamine Using AlIII-DA Complexes at the Hanging Mercury Drop Electrode

“…In recent years, there are some reports with regard to the interaction between some catecholamines and other metal ions such as Fe III , Ge IV , Bi III , Pb II , Co II , and Cd II at the HMDE, [20][21][22][23][24] but the investigation of Al III -DA at the HMDE has never been reported before. In this paper, the electrochemical behaviors of Al III -DA at the HMDE have been investigated systemically.…”