Matrix Modification with Metal Nitrates and Organic Compounds for the Determination of Germanium by Graphite-Furnace Atomic Absorption Spectrometry

Abstract

A mixture of cobalt and aluminum nitrates proved to be useful as a matrix modifier for determination of germanium by graphite-furnace atomic absorption spectrometry. These metal nitrates acted as a thermal stabilizer for germanium in the furnace before atomization, and atomic absorption sensitivity for the analyte was improved by a factor of about 40 over that in the absence of metal nitrate. For the removal of chloride interference in the determination of germanium, a mixture of ammonium acetate with these metal nitrates was suitable as an additive, because chloride formation of aluminum was masked by acetate and the volatile ammonium chloride formed could be easily removed from the furnace. The tolerable concentration of coexisting chlorides was about 10 or more times greater than that in the absence of ammonium acetate. The sulfate interference could also be removed by the addition of a mixture of ascorbic acid and ammonium-EDTA with cobalt and aluminum nitrates. EDTA acted as a masking agent and the formed ammonium sulfate could be easily removed from the furnace. The tolerable concentration of coexisting sulfates was also about 200 times greater than that in the absence of these organic reagents.