EFFECT OF SAMPLE-PREPARATION METHODS ON THE HPLC QUANTITATION OF SOME PHENOLIC ACIDS IN PLANT MATERIALS

Abstract

SUMMARY The extraction yield of phenolic acids from Sambucus nigra L. inflorescence and Polygonum aviculare foliage has been determined for different methods of liquid–solid extraction – Soxhlet extraction, ultrasonicfication (USAE), microwave-assisted extraction (MASE), and accelerated solvent extraction (ASE). Methanol was used as extractant. The crude extracts were evaporated to dryness and prepared for fractionation of the phenolic acids by liquid–liquid extraction (LLE) or solid-phase extraction (SPE). Samples containing the phenolic acid fraction were analysed by RP-HPLC. Quantitative analysis was performed by the external standard method and use of a calibration plot for each standard. It was found that yield depends primarily on the plant material from which the phenolic acid fraction was extracted. For Sambucus nigra L. inflorescence the most effective was exhaustive extraction in a Soxhlet apparatus. For Polygonum aviculare foliage the most effective methods were MASE and USAE. Both LLE and SPE gave similar recoveries and repeatability.