SUPERCRITICAL-FLUID EXTRACTION OF PHENOL COMPOUNDS FROM OLIVE LEAVES

A clean, highly selective supercritical fluid extraction (SFE) method for the isolation of phenols from olive leaf samples was examined. Tot al phenol extracts were determined using the Folin-Ciocalteu reagent. Dried, ground, sieved olive leaf samples (30 mg) are subjected to SFE, using carbon dioxide modified with 10% methanol at 334 bar. 100 degre es C (CO2 density 0.70 g ml(-1)) at a liquid flow-rate of 2 ml min(-1) for 140 min. Diatomaceous earth is used to reduce the void volume of the extraction vessel. The influence of extraction variables such as m odifier content, pressure, temperature, flow-rate, extraction time, an d collection/elution variables, were studied. Supercritical fluid extr acts were screened for acid compounds such as carboxylic acids and phe nols using Electrospray-MS (in the negative ionization mode). SFE was found to produce higher phenol recoveries than sonication in liquid so lvents such as nehexane, diethyl ether and ethyl acetate, However, the extraction yield obtained was only 45%, using liquid methanol. (C) 19 98 Elsevier Science B.V. All rights reserved.