Automated Pretreatment System for the Speciation of Cr(III) and Cr(VI) Using Dual Mini-Columns Packed with Newly Synthesized Chitosan Resin and ME-03 Resin

Chitosan resin possessing the 4-hydroxyphthalic acid moiety (CCTS-HPA resin) was synthesized. This resin could adsorb chromium(VI) at pH 3 to 5, whereas chromium(III) could not be retained in the acidic region. The CCTS-HPA resin was used for collecting chromium(VI), and ME-03 resin was used for collecting chromium(III) before their measurement by ICP-AES measurement. Both resins were packed in mini-columns and installed serially in a laboratory-assembled automated pretreatment system (Auto-Pret System). The system provides a highly sensitive and fully automated procedure for the speciation of chromium(III) and chromium(VI). The proposed system was successfully applied to speciation of chromium(III) and chromium(VI) using 5 ml of water samples. The detection limits (S/N = 3) of chromium(III) and chromium(VI) were 0.06 and 0.04 µg l-1, respectively, along with an analysis time of 7 min 45 s for both chromium species. The lowest determinable concentrations for both chromium species were about 0.5 µg l-1, which was enough for the speciation of chromium in water samples.