Determination of trace amounts of platinum in manganese nodules by solvent extraction/graphite furnace AAS.

Abstract

A rapid and precise method for the determination of Pt in manganese nodules and crusts is presented. The sample of 0.1 g was decomposed with 8 ml of aqua regia and filtered. The filtrate was evaporated to dryness, then dissolved in 20 ml of 20% tartaric acid with heating. After the addition of 0.5 ml iron (III) chloride solution (20 mg Fe/ml) and 0.5 ml of 1% 1, 3-diphenylthiourea in acetone, the mixture was heated for 5 min at about 100°C. The solution was extracted with 1 ml of 1, 2-dichloroethane for 5 min. Platinum in the organic phase was determined by graphite furnace AAS. The limit of detection is 0.05 ppm, and the relative standard deviation in the determination of 0.01 μg to 1.0 μg of Pt is 4 to 16%. The method is satisfactorily applied to USGS manganese nodule reference samples and the manganese nodules and crusts collected from the Central Pacific Ocean, Antarctic Ocean and Ogasawara Plateau.