AN ABSORPTION SPECTROMETRIC STUDY OF MOLYBDOGERMANIC ACID . METHODS FOR DETERMINATION OF GERMANIUM

As the result of a spectrophotometric study of molybdogermanic acid, the conditions required for the formation of a stable form of this heteropoly acid were determined. On the basis of the formation of a stable molybdogermanic acid, four absorption spectrometric methods were developed for the determination of germanium. A direct ultraviolet spectrophotometric method most suitable for determining 1.2-4 ppm germanium in aqueous solution was developed. By extracting molybdogermanic acid with a (1:4) 1-pentanol:diethyl ether mixture, an analogous direct ultraviolet spectrophotometric method having an optimum concentration range of 1 to 3.1 ppm of germanium resulted. An indirect ultraviolet spectrophotometric method based on measurement of the absorptivity of the molybdate resulting from the decomposition of molybdogermanic acid is suitable for the determination of 0.3 to 1.15 ppm of germanium. The molybdate resulting from the decomposition of the heteropoly acid can also be measured by atomic absorption spectrom try at the 313.3 mµ resonance line of molybdenum. This indirect atomic absorption spectrometric method has a percentual concentration limit (PCL) of 0.05 ppm of germanium and shows conformity to Beer's law for the 0 to 1.6 ppm range. © 1969, American Chemical Society. All rights reserved.