Analysis of Rare Flavonoid C-glycosides in Celtis Australis L. by Micellar Electrokinetic Chromatography

This manuscript reports on the first analytical procedure for the determination of flavonoids in Celtis australis. The capillary electrophoretic separation of 8 compounds, most of them flavone C-glycosides, was possible using a borax buffer with pH 9.0, which contained 25mM SDS as detergent and 7.5% of n-butanol as organic modifier. Method validation revealed that the developed assay is repeatable (sigma(rel)<or=4.0%), precise (inter-day sigma(rel)<or=6.7%, intra-day sigma(rel)</=3.9%), accurate (recovery rates from 96.8 to 102.3%), sensitive (LOD: 2.2-1.6microg/ml) and linear (R(2)>or=0.9996) within the tested concentration range. The quantitative analysis of several C. australis samples showed that isovitexin is the most abundant representative (0.06-0.09%), at a rather uniform content of total flavonoids of approx. 0.3% in all specimens.