Determination of four polyphenolic active ingredients from a pharmaceutical preparation by capillary zone electrophoresis with amperometric detection

The simultaneous determination of four active ingredients in Nao Xue Shuan Tablets, including ferulic acid, protocatechuic aldehyde, caffeic acid and protocatechuic acid was performed by capillary zone electrophoresis with amperometric detection (CZE-AD). The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CZE-AD were investigated. Under the optimum conditions, the four analytes could be perfectly separated within 18 min. A 300 μm diameter carbon-disc electrode had a good response at +0.95 V (vs. SCE) for the four analytes. The response was linear over three orders of magnitude with detection limits (S/N = 3) as low as 10^-8 or 10^-9 g/mL for the analytes. The assay results were satisfactory with recoveries in the range of 85.2-93.0% and RSDs less than 3.3%.