Separation and determination of alantolactone and isoalantolactone in traditional Chinese herbs by capillary electrophoresis

A simple micellar electrokinetic chromatography (MEKC) method, using a 20 mM borate buffer (pH 8.0) with 25 mM SDS in the presence of 10% (V/V) methanol, was established for the identification and determination of two isomers, alantolactone (AL) and isoalantolactone (IAL), in the extracts of Inula helenium L. and Inula racemosa Hook f. Regression equations revealed linear relationships (correlation coefficients: 0.9990 for AL, 0.9991 for IAL) between the peak area of AL and IAL and their concentration. The relative standard deviations of the migration time and peak area of the two constituents were 1.51, 1.62 and 2.01, 1.98%, respectively. The recoveries of the two constituents ranged between 95–105% for AL and 93–108% for IAL.