Simultaneous analysis of lead, mercury and selenium species by capillary electrophoresis with combined ethylenediaminetetraacetic acid complexation and field-amplified stacking injection.

In this study, speciation analysis was carried out for multispecies of lead, mercury and selenium by capillary electrophoresis (CE) with combined complexation and field-amplified stacking injection (FASI). Ethylenediaminetetraacetic acid (EDTA) was added to the sample mixture to form UV-absorbing complexes with the analytes, thus enabling direct UV detection. It was also used in the running electrolyte to improve resolution. Under optimal conditions, ten analytes were baseline-separated within 20 min. The influence of operational conditions (pH, EDTA concentration, sodium dodecyl sulfate concentration) on the electrophoretic behavior of the species was studied. The analyte-related parameters were calculated based on the migration equation. Enhancement of detection, up to 1700-fold, was achieved for the charged complexes with FASI, and sub-ng/mL detection limits were obtained. The performance of this method was compared with high-performance liquid chromatography, gas chromatography and other CE procedures.