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(IV) was adsorbed on a mercury electrode in the form of catechol complexes. The differential-pulse polarogram exhibited a well defined cathodic peak at –0.61 V versus Ag-AgCl. From normal- and reverse-pulse polarography, the peak was ascribed to the reduction of germanium-catechol 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 As^III and Sn^II. From a calibration graph of peak current in the differential-pulse mode, the contents of germanium in aluminium-germanium alloys were determined as an application of this technique.