Identification and determination of oligomeric stilbenes in the roots of Caragana species by capillary electrophoresis.

A method based on capillary electrophoresis with electrochemical detection (CE-ED) was employed for the determination of one alkaloid (hypaphorine) and the four oligomeric stilbenes, pallidol, kobophenol A, miyabenol C and (+)-alpha-viniferin in the roots of Caragana species. The five analytes could be well separated within 12 min in a 40 cm length capillary at a separation voltage of 12 kV in a 100 mmol/L borate buffer (pH 10.0). The response was linear over about 3 orders of magnitude for all investigated analytes with detection limits (S/N = 3) ranging from 0.0385 to 0.111 mg/L. The five constituents presented in Caragana sinica can also be detected in the roots of other Caragana species, but their contents were quite different. It is demonstrated that CE-ED is a useful technique for the investigation of some electroactive constituents in plants.