Simultaneous capillary electrophoretic separation of small anions and cations after complexation with ethylenediaminetetraacetic acid

A new approach for simultaneous separation of small inorganic and organic anions and metal cations by capillary electrophoresis is demonstrated. Metal cations in the sample are transformed into their chelates with EDTA and are separated together with the anions using an anionic separation mode. Simultaneous separation of 19 common anions and cations was achieved in about 6 min with the electrolyte containing 5 mM K2CrO4, 3 mM boric acid, 35 microM cetyltrimethylammonium bromide and 12 microM EDTA at pH 8. Limits of detection (s/n = 3) were in the range from 4 ppb for Cl- up to 1250 ppb for Cu-EDTA and RSDs of peak areas ranged from 1.4% for Cl- up to 8.5% for Mn-EDTA chelate. The practical applicability of the method was demonstrated on the analysis of anions and cations in various water samples.