REDUCTIVE COPRECIPITATION AS A SEPARATION METHOD FOR THE DETERMINATION OF GOLD, PALLADIUM, PLATINUM, RHODIUM, SILVER, SELENIUM AND TELLURIUM IN GEOLOGICAL SAMPLES BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

A method for the separation of Au, Pd, Pt, Rh, Ag, Te and Se from geological samples at trace levels is presented. The elements are separated from the matrix after dissolution by reductive coprecipitation using mercury as a collector and tin(II) chloride as a reductant. The efficiency of coprecipitation is studied by varying the acidity of the solutions and the amount of collector. The analyte elements are determined by graphite furnace atomic absorption spectrometry. In the determination of volatile elements (Te, Au and Ag), matrix modification with iridium is used. Selenium is determined with a mixed matrix modifier containing ascorbic acid and iridium. The method is tested by analysing geochemical reference samples. © 1990.