Analysis of phenolic acids in honeys of different floral origin by solid-phase extraction and high-performance liquid chromatography

The determination of 18 aromatic and arylaliphatic carboxylic acids in honey from different floral origin using solid-phase extraction (SPE) and reversed-phase high performance liquid chromatography (RP-HPLC) is reported. The behaviour of the solutes on SPE cartridges was predicted from preliminary calculations involving the pK(a) constants of the carboxylic groups, the n-octanol:water partition coefficients and the distribution coefficients at different pH values of the conditioning and washing solvents. The proposed SPE isolation and pre-concentration of the acids was achieved on reversed-phase Bond Elut C18 cartridges using an acetonitrile:tetrahydrofuran (1:1, v/v) elution system. RP-HPLC separations were performed on a Spherisorb ODS-2 column using linear gradient elution with a mobile phase composed of 20 mm phosphate buffer (pH 2.92) and methanol, and with UV detection. The reported SPE and RP-HPLC methods were applied to the analysis of 49 authentic honey samples from various floral sources and the results indicate that they may serve with respect to the quantitative control of a number of phenolic acids in plant-derived foods and medicinal plants.