Supercritical fluid extraction of resveratrol from grape skin of Vitis vinifera and determination by HPLC.

Supercritical fluid extraction of resveratrol from grape skin of Vitis vinifera was studied. Extraction variables such pressure, modifier concentration (ethanol), and extraction time were optimised. Final extraction conditions were: 40 degrees C, 150 bar, 7.5% ethanol and extraction time 15 min. Extraction recovery and precision (variation coefficient between 0.2 and 1.0%) were calculated. The resveratrol content in the ethanolic extract was determined by HPLC with UV detection at 306 nm. Acetic acid-methanol-water was used as the mobile phase, and C-18 and C-8 columns were tested, instrumental parameters were optimised, and analytical parameters were calculated (lineal interval 0-75 mg l(-1), detection limit 0.1 mg l(-1), sensitivity 125530 mg(-1) mg l(-1), coefficient variation 0.8-1.6%). Six different varieties of grape skin, from the same geographical area and representative of the wine elaboration, were analysed.