Simple, Rapid and Sensitive Determination of Bismuth in Iron and Steel Based on In-line Preconcentration/separation Directly Coupled with Spectrophotometric Detection in a Continuous Flow System

Abstract

A novel flow injection system is presented for simple, rapid and selective determination of bismuth at sub-ppm levels in iron and steel by coupling in-line anion exchange preconcentration/separation directly with spectrophotometric detection. Bismuth in 0.5 M HCl solution was adsorbed on a small column packed with Dowex 1X8 anion exchange resin and desorbed with a small volume of 0.5 M H2SO4, which allowed effective preconcentration/separation of bismuth from a large excess of iron(III) and other coexistent elements in the steel samples. Bismuth was detected by complex formation with iodide in 0.5 M H2SO4 yielding a yellow color. Various analytical parameters were investigated, and optimal conditions and manifold configurations were established. A linear calibration using a 10 m sample loop was obtained for bismuth in the range of 0.005-0.30 ppm. The relative standard deviation for 0.1 ppm bismuth in the solution was 0.8% (n=5). The estimated limit of determination is ca. 0.2 ppm in steel sample when a 5 m sample loop (1.0 mm i.d.) is used. The results for analyses of steel samples by the present FI system correspond well with those obtained by AAS methods. The present FI system affords a rapid and simple analysis: only 12 min is required for analytical measurement after sample injection, and no complicated manual operation is involved.