1999 Volume 85 Issue 2 Pages 135-137
Fluoride separation-molybdosilicic acid blue spectrophotometry was applied to the determination of trace amounts of silicon in niobium and tantalum samples. After the sample was dissolved in hydrofluoric acid and nitric acid, the silicon was evolved by heating to 300°C in the presence of sulfuric acid. The liberated silicon tetra-fluoride was absorbed into the solution containing boric acid by sucking the evolved gas at a flow rate of 300 ml/min. Then the silicon in the absorbent was determined by Molybdenum Blue spectrophotometry. By this method, silicon at ppm level in commercially available metals was successfully determined. Recovery was 105% for niobium sample and the detection limit given by 3σ of blank value was 0.6ppm silicon in the metal sample.
