Effect of sample-preparation methods on the quantification of selected flavonoids in plant materials by high performance liquid chromatography

Abstract

Extraction yield of flavonoids from plant material Sambucus nigra L. inflorescence and Polygonum aviculare herb was determined by use of various methods of liquid-solid extraction - Soxhlet extraction, ultrasonification (USAE), microwaveassisted extraction (MASE), and accelerated solvent extraction (ASE). Methanol was used as extractant. Crude extracts were evaporated to dryness and prepared to achieve fractionation of flavonoids by LLE or SPE. Samples containing the flavonoid fraction were analysed by RP-HPLC. For quantitative purposes the external standard method with a calibration plot for every standard was used. It was found that yield depends first of all on the plant material from which flavonoid fraction was extracted. For Sambucus nigra L. inflorescence the most effective method was exhaustive extraction in a Soxhlet apparatus. For Polygonum aviculare the most effective method was ASE. The best purification method was SPE on C18 adsorbent, which resulted in the highest recoveries and repeatabilities. © 2008 Akadémiai Kiadó, Budapest.