Determination of Active Ingredients of Origanum Vulgare L. and Its Medicinal Preparations by Capillary Electrophoresis with Electrochemical Detection

Abstract

A method based on capillary electrophoresis with electrochemical detection (CE‐ED) has been developed for the first time for the separation and determination of isovanillic acid, vanillic acid, quercetin, rosmarinic acid, caffeic acid, and protocatechuic acid in Origanum vulgare L. and its medicinal preparations. The effects of working electrode potential, pH level, concentration of running buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmol L⁻¹ borate buffer (pH 8.7) within 21 min. A 300‐µm diameter carbon disk electrode has a good response at +0.95 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 4×10⁻⁸ g mL⁻¹ to 2×10⁻⁷ g mL⁻¹ for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results.

Keywords:

• Capillary electrophoresis
• electrochemical detection
• Origanum vulgare L.

This work is supported financially by the Natural Science Research Foundation of the Shanghai Science and Technology Committee (Grant No. 04ZR14041).