Pre-concentration of non-uniform field electrophoresis for sample introduction of capillary electrophoresis

A new sample introduction method of capillary electrophoresis, in which fie ld-amplified sample injection was combined with a pre-concentration of non- uniform field electrophoresis, is presented in this paper, With an addition al pre-concentration voltage applied to sample solution, a non-uniform elec tric field was generated, with which analytical cations or anions were pre- concentrated around an electrode adjacent to the injection end of capillary . After the pre-concentration, analytical ions were injected into the capil lary and stacked at the boundary between sample and buffer solution inside capillary by field-amplified injection technique. In contrast to the conven tional field-amplified injection, larger concentration factor and higher an alytical sensitivity were obtained with the improved pre-concentration meth od. Its concentration factor was about 10 similar to 15 fold as that of fie ld-amplified sample injection. (C) 2001 Elsevier Science B.V. All rights re served.