Two-Phase Aqueous Extraction of Chromium and its Application to Speciation Analysis of Chromium in Plasma

 This work proposes a new extraction method for chromium based on the two-phase aqueous system isopropyl alcohol-ammonium sulfate-ammonium thiocyanate (i-PrOH-(NH₄)₂SO₄-NH₄SCN), and the related experimental conditions are optimized. The results show that chromium (III) can be quantitatively extracted under the selected conditions: 4 mL of i-PrOH, 200 μL of 2 mol/L sulfuric acid, 1 mL of 4 mol/L NH₄SCN and 3 mL of saturated (NH₄)₂SO₄ solution (V_total=10 mL). Application of the proposed method to speciation analysis of plasma chromium was also investigated and satisfactory results were obtained. Received May 22, 1999. Revision November 8, 1999.