Abstract
In order to determine trace amounts of As, Bi, Sb and Sn in low alloy steels by ICP-OES, the authors investigated a separation and pre-concentration procedure using a co-precipitation technique with manganese(IV) oxide (MnO2). After dissolving the sample, these analyte elements in the solution were precipitated together with MnO2 formed by a reaction between Mn(II) and Mn(VII). The collected precipitate was decomposed in a mixed HNO3 and H2SO4 solution together with the filter paper, and heated to fume. Then, the analyte elements were analyzed by ICP-OES. The authors investigated the influence of both coexisting acids and elements on the separation of the analyte elements by co-precipitation so as to optimize the conditions for the analytical procedure. Not only As, Sb and Sn in a HNO3 solution, but also Bi and Sn in a H2SO4 solution could be simultaneously and quantitatively separated from the iron matrix by co-precipitating with MnO2. Using 41.9 mg of Mn(VII) as the reagent for co-precipitation could prevent a decrease in the recoveries of the analyte elements due to interfering with precipitating MnO2 by chromium ; accordingly, the authors applied the proposed method to the analysis of samples containing 5-7.5mass% chromium. In determinations of As, Bi, Sb and Sn in certified reference materials, good agreement between the certified values and the analytical values was obtained. The detection limits (3σ of blank values) obtained were sub-μg g−1 levels for all of the analyte elements. Therefore, the authors confirmed that the proposed method was useful for simultaneous determination of trace As, Bi, Sb and Sn in the low alloy steels.
