Determination of Phenolic Compounds in the Hull and Flour of Buckwheat (Fagopyrum esculentum Moench) by Capillary Electrophoresis with Electrochemical Detection

Abstract

A simple, reliable and reproducible method, based on capillary electrophoresis with electrochemical detection (CE‐ED), for the determination of phenolic compounds of buckwheat (Fagopyrum esculentum Moench) hulls and flour was reported. The mainly phenolic components consist of (−)‐epicatechin, rutin, hyperoside, and quercetin. Operated in a wall‐jet configuration, a 300 µm diameter carbon disk electrode was used as the working electrode, which exhibits good response at +0.90 V (versus SCE) for all relevant analytes. The potential effects of working electrode, pH and concentration of buffer, separation voltage, and injection time on CE‐ED were investigated. Under the optimum conditions, the analytes can be separated in a 50 mmol/L borate buffer (pH = 8.7) within 16 min. The response was linear over three orders of magnitude with detection limit (S/N = 3) ranging from 2 × 10⁻⁷ g/mL to 5 × 10⁻⁷ g/mL for all analytes. This method has been used for the determination of phenolic compounds in buchwheat (Fagopyrum esculentum Moench) hulls and flour, and the assay result was satisfactory.

Keywords:

• Buckwheat
• Phenolics
• Capillary electrophoresis
• Electrochemical detection

Acknowledgements

The authors are grateful for the financial support provided by the National Science Fund, China (No. 20375013) and Science Fund for Young Creative Scholars, Fujian, China (No. 2003J037).