PREVENTION OF PEAK OVERLAP IN THE CAPILLARY ELECTROPHORETIC SEPARATION OF INORGANIC CATIONS BY USE OF A POSITIVELY CHARGED COATED CAPILLARY

The use of a quaternary amine-coated capillary in the separation of al kali and alkaline earth cations yielded a decisively better resolution than is possible with a conventional fused-silica capillary. Improved resolution is required in particular when sample solutions contain sm all amounts of cations in the presence of others with much higher conc entrations. The determination of, for example, Mg2+ in seawater is not possible with standard conditions, as the large Naf peak overlaps str ongly with the peak due to Mg2+, With the coated capillary, baseline r esolved separations without peak overlapping could readily be obtained for seawater, albeit at a somewhat longer analysis time. The approach might also be useful in the analysis of other cations and types of sa mples. (C) 1997 Elsevier Science B.V.