High-Performance Liquid Chromatographic Determination of Phenolic Acids Isolated from Plants

Abstract

A simple and rapid method is described for the estimation by high-performance liquid chromatography of cis and trans isomers of the substituted cinnamic acids, p-coumaric (p-CA) and ferulic (FA), using p-anisic acid (p-AA) as internal standard. Chromatographic separation and quantification were performed on a reversed-phase Nova-Pak C₁₈ column with isocratic elution water-n-butanol-acetic acid (98:1.5:0.5). A flow-rate of 1.5 ml/min, a column temperature of 35°C and detection at 270 nm were employed. As little as 175ng/ml for p-CA and 63 ng/ml for FA can be estimated by this procedure with a 20 μl injection. Application of this method are illustrated by estimation of these acids in extracts, prepared with 1 M sodium hydroxide of barley straw, mixed grass hay and alfalfa hay.