Rapid analysis of sennoside A and B in health teas by capillary electrophoresis

A method for determinations of sennoside A (SA) and sennoside B (SB) included in "health tea" by capillary electrophoresis (CE) was developed. A 0.02M sodium berate solution adjusted to pH 10.8 was used for the running buffer. SA and SE were detected at UV 260 nm. C.V. (%) of migration times for SA and SE were 0.07 and 0.06%, and that of the peak area was 1.3%. The detection limits of SA and SE were 2 ppm. As CE has high theoretical plates, the refinement of sample was simplified and the time for analyzing extracts was shortened to about 1/3 of that by HPLC. Six samples of "health tea," advertised with a likely effect of losing weight, were examined and SA and SE were detected from three of the samples. The total concentrations of SA and SE were 0.11-0.28%.