Determination of eleven flavonoids in chamomile and linden extracts by capillary electrophoresis
A sensitive, dependable, simple and rapid method based on capillary electrophoresis with diode array detection (CE-DAD) was developed for identification and determination of eleven flavonoids (apigetrin, naringin, naringenin, catechin, galangin, apigenin, luteolin, quercetin, myricetin, kaempferol, and kaempferide) in chamomile and linden flower extracts. Several parameters which influence the separation were investigated to determine the optimum conditions. At room temperature, the eleven flavonoids could be well separated within 11 min. in a 55 cm length capillary at a separation voltage of 24 kV with 40 mM borate buffer (pH 8.9). Under optimum conditions, linearity was achieved within the concentration ranges of 2.5–100.0 μM for all analytes except myricetin and luteolin (5.0–100.0 μM) with correlation coefficients ≥ 0.999. The method was successfully applied to the determination of flavonoids in plant samples such as chamomile and linden flowers with satisfactory recoveries.