Supercritical fluid extraction and HPLC determination of relevant polyphenolic compounds in grape skin

摘要: The polyphenols determined are: (+)-catechin, (–)-epicatechin, rutin, quercetin and trans-resveratrol. Suitable conditions of supercritical fluid extraction were established using ethanol as a modifier the polarity solvent (supercritical carbon dioxide). Final were: 20% v/v ethanol, 60°C, 250 bars flow rate 2 mL/min. Static step time dynamic selected grape skin sample. extract was collected in water; more polar ((+)-catechin (–)-epicatechin) remain solution but trans-resveratrol precipitate this medium, thereby extracted filtered. (+)-Catechin (–)-epicatechin liquid fraction, while solid containing trans-resveratrol, solved with ethanol/H2O (40:60). HPLC determination carried out at C18 stationary phase, ethanol/water/acetic acid mobile phases UV-visible diode array detection. Due to significant differences between polyphenols, two different used. An (5:93:2) phase used determine (+)-catechin (280 nm) nm). On other hand, rutin (254 nm), (306 resolved (40:58:2) phase. Instrumental parameters optimised analytical obtained. method validated applied five varieties Vitis vinifera from geographical area Valencia.