Microemulsion electrokinetic chromatography of diphenylhydrazones of dicarbonyl sugars

A mixture of diphenylhydrazones of dicarbonyl sugars was separated by microemulsion electrokinetic chromatography. Separations were carried out with a laboratory-made capillary electrophoresis apparatus using an untreated fused-silica capillary [70 cm (effective length 65 cm)x50 mu m I.D.] at 20 kV; detection was at 220 nm. The microemulsion system was composed of 5 mM berate buffer, pH 8.0 (89.27%, w/w), sodium dodecyl sulphate (SDS; 3.31%, w/w), n-butanol (6.61%, w/w) and n-octanol (0.81%, w/w). Separation by microemulsion electrokinetic chromatography was significantly better then separation obtained by routine micellar electrokinetic chromatography with SDS and was characterized by a much higher efficiency (theoretical plates ranged from 100.10(3) to 254.10(3)). SDS-micellar electrokinetic chromatography resolved only one compound from a joint peak of two sugars and from a cluster peak consisting of seven compounds. Applicability to the analysis of biological samples was also demonstrated.