Absorptiometric Determination of Micro-amounts of Iron in Nuclear Grade Graphite and Urania-Graphite Fuel; Nitroso R Salt Method after Coprecipitation of Iron with Manganese Dioxide

Abstract

Abstract An absorptiometric determination of micro-amounts of iron with nitroso R salt was satisfactorily applied to the routine analysis of nuclear grade graphite. An ashed sample is brought into a solution and the color of iron is developed by the reagent with the aid of hydroxylamine sulfate. Adjustment of pH to the optimum range is easily made by the addition of a definite amount of an acetate buffer. The intensity of the color is measured at 715 mμ. The range of the determination covers 2 to 75 p. p. m. when 1 g. of a sample is taken, the final volume being 25 ml. In the case of a sample of urania-graphite fuel, the ash is fumed with perchloric acid and a preliminary separation is made by coprecipitation with manganese dioxide which is produced by the oxidation of manganese (II) ion with hydrogen peroxide in a hot ammoniacal carbonate solution. The recovery of iron is quantitative and the removal of diverse ions is satisfactory. All of the uranium is also removed here. Contamination with foreign iron from a drill used for sampling and from the platinum or percelain crucibles used is negligible. The effect of diverse ions on the absorptiometry was also examined.