Simultaneous determination of iridoids, phenylpropanoids and flavonoids in Lippia alba extracts by micellar electrokinetic capillary chromatography

A new method for the determination of three different classes of secondary metabolites (flavonoids, iridoids and phenylpropanoids) present in extracts of Lippia alba leaves based on CE is described. The capillary electrophoretic separation of these compounds was possible employing a 50 mM borax buffer containing 75 mM SDS and 5% isopropanol as organic modifier. The analytes could be well resolved in 25 min and accurately determined in different chemotypes of Lippia alba specimens. Method validation assured the compliance of the assay to International Conference on Harmonization standards (ICH) (correlation coefficients ≥0.9944, LOD 23.0-65.0 μg ml−1 and LOQ 38.0-119.0 μg ml−1, recovery rates from 97 to 101%, intermediate precision ≤2.1%, and repeatability ≤5.0%). The proposed method was compared with a previously validated HPLC method using eight samples as well as by statistical means (t-test). In all the samples, T calculated was less than T critical with a significance level of 5%, thus demonstrating that CE is a good alternative for the separation and quantification of polar compounds in plant extracts.