STUDY OF ISOTACHOPHORETIC SEPARATION BEHAVIOR OF METAL-CATIONS BY MEANS OF PARTICLE-INDUCED X-RAY-EMISSION .1. SEPARATION OF 20 METAL-CATIONS USING AN ACETIC-ACID BUFFER SYSTEM AND ALPHA-HYDROXYISOBUTYRIC ACID COMPLEX-FORMING SYSTEM

Twenty metal ions were separated isotachophoretically and the zones were fractionated and analysed off-line by particle-induced X-ray emission (PIXE). The recovery, migration order and separation efficiency were studied in relation to the use of a complexing agent, alpha-hydroxyisobutyric acid (HIB). The migration order using the WNH4Ac system [aqueous solution (W) of NH4+ as the leading ion and acetate (Ac) ion as the pH-buffering counter ion, pH = 4.8] was Ba, Sr, Ca, Na, Mg, (Mn, Fe(II), Co), Ni, Zn, La, Ce, Cd, Y, Li, Lu, Gd, (Cu, Pb) and Zr(IV)O, Fe(III)). The order using the WNH4Ac-HIB system was Ba, Sr, Ca, Na, Mg, Mn, Fe(II), Cd, Co, Li, Ni, Zn, La, Pb, Ce, Gd, Cu, Y, Zr(IV)O, Lu. The recovery of the metal cations was 100% with both electrolyte systems, except for Fe(II) and Zr(IV)O. The low recovery of Zr(IV)O was due to hydroxyl complex formation and that of Fe(II) to hydroxyl complex formation of Fe(III), the oxidation product of Fe(II). For these ions, the recovery with the WNH4Ac-HIB system was lower than that with the WNH4Ac system.