Separation selectivity of some ethylenediaminetetraacetic acid and cyclohexane-1,2-diaminetetraacetic acid complexes in column and ion electrokinetic chromatography.

The complexes of Mn2+, Cd2+, Fe3+, Pb2+, Ni2+, Co2+, Zn2+ and Cu2+ with EDTA and cyclohexane-1,2-diaminetetraacetic acid (CDTA) were separated and detected in column and ion electrokinetic chromatography with suppressed conductivity and direct UV detection, respectively. In column ion chromatography (IC) these complexes were separated on an IonPac AS4A anion-exchange column (Dionex, USA). Parameters of carrier electrolyte, which were examined in the ion electrokinetic chromatography (IEKC) mode, include polymer and sulfate concentrations. In IEKC separation selectivity of complexes with poly(diallyldimethylammonium) cation as modifier is similar as for an IonPac AS4A column both for EDTA and CDTA chelates. It was shown that the ion-exchange capacity of the electrokinetic system is more than 100-times lower than the capacity of the IC column for the same peak resolution. In comparison with column main advantages of electrokinetic version are high separation efficiency (220,000-390,000 theoretical plates) and the absence of the analyte interaction with the sorbent matrix.