Determination of trace selenium in calcium by reduced gasification/ICP-AES method after distillation with hydroiodic acid

To determine trace amounts of selenium in calcium, a separating gathering method, in which selenium is distilled as the halogenide, was applied. A prescribed sample is added to phosphoric acid (15 w/v% ), hydroiodic acid (2.0 w/v% ) and metallic zinc solution (0.2 w/v% ) for distillation. The absorption collecting solution for selenium consisted of a mixed solution of perchloric acid-potassium permanganate-oxalic acid. By using the reduced gasification/ICP-AES method, a quantitative analytical method for trace amounts of selenium after prereduction of selenium(VI) to selenium(IV) in collecting solution was developed. The relative standard deviation (n=8) of selenium coexisting with 5000 μg cm-3 of calcium was 2.0%. The limit of detection was 0.05 ng cm -3. When this method was applied to determine trace amounts of selenium in calcium carbonate, highly accurate result (2±0.05 ng cm-3) were obtained.