GRAPHITE-FURNACE AAS DETERMINATION OF SIL VER IN SEAWATER AFTER SOLVENT-EXTRACTION AND BACK-EXTRACTION

A method for the determination of silver at ng/l levels in seawater is described. Silver is extracted as the thiocyanato complex with trioct ylmethylammonium chloride is xylene and subsequently back-extracted in to 0.1 mi of nitric acid and 0.1 mi of 500 mu g/ml indium solution. Th e back-extracted solution containing indium as a matrix modifier is su itable for the determination of silver by graphite furnace AAS. The de tection limit was found to be 1.3 ng/l of silver in the initial soluti on based on a 150-fold preconcentration with a combined extraction and back-extraction. The proposed method is simple and rapid for the dete rmination of ultra-trace amounts of silver in seawater.