Determination of Phenols, Flavones, and Lignans in Virgin Olive Oils by Solid-Phase Extraction and High-Performance Liquid Chromatography with Diode Array Ultraviolet Detection

Abstract

A simple analytical method for the quantitative determination of phenols, flavones, and lignans in virgin olive oils was developed. The polar fraction was isolated from small amounts of oil sample (2.5 g) by solid-phase extraction (SPE) using diol-phase cartridges, and the extract was analyzed by reversed-phase HPLC coupled with diode array UV detection. Chromatographic separation of pinoresinol, cinnamic acid, and 1-acetoxypinoresinol was achieved. Repeatability (RSD < 6.5%), recovery (> 90%), and response factors for each identified component were determined. SPE on amino-phase cartridges was used for isolating acidic phenols and as an aid for phenol identification. For the first time, 2-(4-hydroxyphenyl)ethyl acetate was detected in olive oils. The aldehydic structure of the ligstroside aglycon was confirmed by NMR spectroscopy. The colorimetric determination of total o-diphenolic compounds by reaction with molybdate was consistent with their HPLC determination. Differences between results obtained by liquid-liquid extraction and SPE were not statistically significant.

Phenolic Molecules in Virgin Olive Oils: a Survey of Their Sensory Properties, Health Effects, Antioxidant Activity and Analytical Methods. An Overview of the Last Decade Alessandra

“…Summary of separation of phenolic compounds in the polar fraction of VOO using HPLC-NMR (as coupled techniques or by NMR as off-line technique after HPLC). GC-MS [192] [174] reported the first application of the hyphenated LC-SPE-NMR technique using postcolumn solid-phase extraction to direct identification of new phenolic compounds in the polar fraction of VOO. The addition of a post-column SPE system to replace of the loop system of the LC-NMR, resulted in higher sensitivity (significant increase of the signal to noise [S/N] ratio); in fact, S/N improvements by up to a factor of 4 could be demonstrated with this new technology [16].…”

Cold-pressed pumpkin seed (<em>Cucurbita pepo</em> L.) oils from the central Anatolia region of Turkey: Characterization of phytosterols, squalene, tocols, phenolic acids, carotenoids and fatty acid bioactive compounds

“…The phenolic acids were extracted according to the method of Mateos et al, (2001) with some modifications. 2.500±0.001 g of PSO sample were weighed, and dissolved in 6 mL of hexane.…”

Characterisation of Phenolic Compounds in Oils Produced From Frosted Olives

“…Other reference compounds used for peak identification were vanillin, cinnamic acid, vanillic acid, mandelic acid and tyrosol (Sigma Aldrich) and caffeic acid (TCI -Tokyo Kasei Kogyo Co). Individuals phenols were identify by comparison with commercial standards supplied and references chromatograms (Mateos, R. et al, 2001;Garcia, A., Brenes, M. and Romero, C., 2001). The quantification was carried out at 280 nm.…”