Determination of trace amounts of bismuth in ferrous alloys by solvent extraction followed by atomic-absorption spectrophotometry

Abstract

A method is described for the atomic-absorption spectrophotometric determination of 2 to 130 µg g^–1 of bismuth in cast irons and stainless steels. From an aqueous solution of an alloy, 2·3 M in hydrochloric acid, 0·09 M in ascorbic acid and 0·2 M in potassium iodide, the bismuth was extracted quantitatively into isobutyl methyl ketone, by shaking the mixture once, while the base elements remained in the aqueous phase. After concentrating it, the organic phase was nebulised into an air-acetylene flame of a Unicam SP90 atomic-absorption spectrophotometer. The standard deviations in the errors from the means for various cast irons and stainless steels were 1·2 and 1·4 µg g^–1, respectively. The results of applying the solvent-extraction procedure to twenty-seven other elements of interest to the steelmaker are also reported.