日本分析化学会 Acta Medica Okayama 0910-6340 18 10 2002 Adsorption Behavior of Mercury and Precious Metals on Cross- Linked Chitosan and the Removal of Ultratrace Amounts of Mercury in Concentrated Hydrochloric Acid by a Column Treatment with Cross-Linked Chitosan 1121 1125 EN Koji Oshita Mitsuko Oshima Yun-hua Gao Kyue-Hyung Lee Shoji Motomizu Cross-linked chitosan was synthesized with chitosan and ethylene glycol diglycidyl ether. The adsorption behavior of trace amounts of metal ions on the cross-linked chitosan was systematically examined by packing it in a mini-column, passing a metal solution through it and measuring metal ions in the effluent by ICP-MS. The cross-linked chitosan adsorbed mercury and precious metals (Pd, Pt, and Au) at pH values from acidic to neutral. Especially, mercury in concentrated hydrochloric acids could be adsorbed on cross-linked chitosan quantitatively by an anion-exchange mechanism in the form of a stable chloride complex. This method was applied to the removal of mercury from commercially available hydrochloric acid; more than 97% of mercury was removed, and the residual mercury in the hydrochloric acid (Grade: for trace analysis) was found to be 0.15 ppb. Mercury adsorbed on the cross-linked chitosan could be easily desorbed with an eluent containing 1 M hydrochloric acid and 0.05 M thiourea. The thus-refreshed crosslinked chitosan could be repeatedly used for the removal of mercury in hydrochloric acid. No potential conflict of interest relevant to this article was reported.

日本分析化学会 Acta Medica Okayama 0910-6340 16 12 2000 Adsorption Behavior of Metal Ions on Cross-linked Chitosan and the Determination of Oxoanions after Pretreatment with a Chitosan Column 1303 1308 EN Yunhua Gao Kyue-Hyung Lee Mitsuko Oshima Shoji Motomizu The adsorption behavior of 60 elements at the 10 ng ml(-1) level on high-porous cross-linked chitosan in a packed mini-column was systematically examined. The chitosan used could adsorb anionic species quantitatively as oxoanions or chloro complex anions of metals, such as Ti, V, Mo, W, Ga, Bi, Au(III), Pt(IV) and Pd(II), in sample solutions by an ion-exchange mechanism, and could adsorb some metal ions by a chelating mechanism. Most of the metal ions adsorbed on the chitosan were eluted with 1 M nitric acid, and other noble metals, such as Au, Pt and Pd, were eluted by a solution containing 1 M hydrochloric acid and 0.05 M thiourea. The adsorption fraction of metal ions was investigated by measuring metal ions in eluates by ICP-MS. By using the proposed column pretreatment method, metal ions present as their oxoanions in river-water samples, such as Ti, V, Mo, W, Ga and Bi, were collected on the cross-linked chitosan, eluted and determined. The method was applied to an analysis of reference materials distributed by the Japan Society for Analytical Chemistry: JAC 0031 and JAC 0032. The analytical results agreed closely with other reference values. No potential conflict of interest relevant to this article was reported.