Determination of gentiopicroside in extracts of Centaurium erythreae and Gentiana lutea by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography has been developed as a promising method for the determination of gentiopicroside in plant samples. The separation conditions have been optimised with respect to the different parameters including SDS concentration, pH, and ion strength of the background electrolyte, and temperature of capillary. A buffer consisting of 100 mM SDS in 20 mM sodium dihydrogen phosphate, 20 mM disodium tetraborate pH 8.6 was found to be the most suitable electrolyte for this separation. The applied voltage of 28 kV (positive polarity) and the temperature of capillary 20 degrees C gave the best analysis of gentiopicroside. The linear detection range for concentration versus peak area for the assay is from 5 to 500 mu g. mL(-1) (correlation coefficient 0.9998) with a detection limit of 0.3 1.18. . mL(-1). The inter-day reproducibility of the peak area was below 2.5% and the inter-day reproducibility of the migration time was below 0.16%.