SEPARATION OF RARE-EARTH IONS BY ISOTACHOPHORESIS AND CAPILLARY-ZONE-ELECTROPHORESIS

The simultaneous separations of 15 rare-earth (RE) ions including yttr ium and lanthanide both by isotachophoresis (ITP) and by capillary zon e electrophoresis (CZE) were achieved by using the developed electroly te systems containing alpha-hydroxyisobutyric acid (HIBA) as main comp lexing agent and malonic acid as the assistant one. The successful sep aration of Y3+ from Dy3+ without loss of the separation of Eu3+ and Gd 3+ was briefly summarized. Based on the assumed equilibria existed in steady state zone while using such an electrolyte system with binary c omplexing agents, the effective mobilities of the RE complex ions and the qualitative indicies (R-E, the ratio of the specific conductivity of the sample zone to that of the leading zone) for the RE complex zon e were theoretically simulated. The reason for the successful separati on was clarified from the view of complex formation, and the simulated isotachopherogram for an optimum electrolyte system was then obtained . The validity of the simulation was checked by comparison of the simu lated R-E with the observed ones. Furthermore, the historic sample did ym prepared from a RE ore by Brauner was analyzed by ITP-particle-indu ced X-ray emission as well as by CZE, where the supporting electrolyte for CZE analysis is 30 mM creatinine containing 3 mM HIBA and 0.4 mM malonic acid buffered by 2-ethylbutryric acid to pH 4.8. (C) 1998 Else vier Science B.V.