Quantitative and qualitative analysis of flavonoid markers in Frucus aurantii of different geographical origin by capillary electrophoresis with electrochemical detection.

A capillary electrophoresis with electrochemical detection (CE-ED) method was developed for the simultaneous determination of four major flavonoid markers (synephrine, naringin, hesperidin and naringenin) in Frucus aurantii of different geographical origin. Operated in a wall-jet configuration, a 300 microm diameter carbon disc electrode was used as the working electrode, which exhibits a good response at +0.85 V (versus saturated calomel electrode) for the analytes. Under the optimum conditions, the analytes were baseline separated within 20 min in a 80 mmol/L borax buffer (pH 8.45). The intra-day relative standard deviations (R.S.D.) and inter-day R.S.D.s were based on the analysis of the standard solution on the same day and on the following 6 consecutive days. The intra-day R.S.D.s ranged from 0.8% (naringin) to 3.6% (hesperidin). The inter-day R.S.D.s ranged from 1.2% (hesperidin) to 4.6% (naringenin). Calibration curves were linear in ranges between 0.05 and 1000 microg/mL for the markers. Limits of detection ranged from a low of 1 x 10(-8)g/mL (hesperidin) to a high of 5 x 10(-7)g/mL (naringin). The method was successfully used in the analysis of F. aurantii of different geographical origin with relatively simple extraction procedures, and the assay results were satisfactory.