Development and validation of a high-performance liquid chromatographic method for the analysis of antioxidative phenolic compounds in fennel using a narrow bore reversed phase C18 column

A simple high-performance liquid chromatography (HPLC) method for the separation and quantitative determination of the main antioxidant phenolic compounds from bitter fennel, Foeniculum vulgare, was developed. The use of a narrow bore reversed phase (RP) C18 column and an acidic mobile phase enabled ten compounds (caffeoylquinic acids, dicaffeoylquinic acids, flavonoids and rosmarinic acid) to be separated within a 40 min time analysis. The method was validated to demonstrate its selectivity, linearity, precision, accuracy and robustness. In addition, some parameters were studied to optimize the complete extraction of the phenolic compounds. The method was applied to the evaluation of three different fennel materials: distilled and non-distilled aerial parts, as well as defatted fruits. Distilled fennel was found to contain a higher proportion of antioxidant phenolic compounds than the non-distilled plan material.