In-Capillary Derivatization and Preconcentration for CE of Metal Ions as Their Phenanthroline Complexes

A simple and automated method involving in-capillary derivatization and in-capillary preconcentration was developed for the simultaneous determination of metal ions by capillary zone electrophoresis. Fe(II), Zn(II), Cu(II) and Cd(II) were derivatized using 1,10-phenanthroline as the derivatizing agent. The in-capillary derivatization and in-capillary preconcentration via large volume injection were performed sequentially as follows: 60 mmol L^?1 1,10-phenanthroline was first hydrodynamically injected (0.2 psi) for 2 s; metal ions were introduced by hydrodynamic injection (0.5 psi) for 60 s; 0.2 mol L^?1 acetate pH 5.5 containing 20 % methanol was used as the running buffer. Four metal ions can be determined within 8 min using 16 kV. The resulting preconcentration factors were in the range 12–21. Good linearity was obtained for concentrations of 0.1–8.0 mg L^?1 (r ² > 0.990). The mean recoveries of the metal ions evaluated by fortification of wine samples were in the range 90–102 %. The limits of detection ranged from 0.05 to 0.2 mg L^?1. The proposed method can be applied for directly determining metal ions in wine samples.