USE OF TRIETHYLENETETRAMINEHEXAACETIC ACID COMBINED WITH FIELD AMPLIFIED SAMPLE INJECTION IN SPECIATION ANALYSIS BY CAPILLARY-ELECTROPHORESIS

Simultaneous speciation of lead, mercury, and selenium was carried out by capillary electrophoresis. The method used a polyaminocarboxylic a cid, triethylenetetraminehexaacetic acid (TTHA), as an off-column comp lexing agent to form W-absorbing complexes with the analytes for direc t UV detection. TTHA was also added to the background electrolyte for the on-column complexations of the analytes, as well as for improving resolution and detection. To describe the migration behavior of the co mplexes, a theoretical model, considerating pH value and the concentra tions of TTHA and SDS, was proposed. The parameters in the model were calculated on the basis of the experimental data, by nonlinear regress ion. The results were in good agreement with those from the literature . The model can be used for the prediction of migration behavior and f or the optimization of the separation conditions. Field-amplified stac king injection was performed because the complexes were charged. Up to 1500-fold on-line enrichment and down to sub-nanogram-per-milliliter detection limits were obtained for the analytes under the optimal stac king conditions. Finally, the applicability of the method was evaluate d on seawater samples.