High-throughput determination of phenolic compounds in extra virgin olive oil using dispersive liquid-liquid microextraction-CZE

ROMINA PAULA MONASTERIO; MARIA DE LOS ANGELES FERNANDEZ; VERONICA CAROLINA SOTO VARGAS; MARIA FERNANDA SILVA

Baltimore

Simposio; 19th International Symposium on Electro- and Liquid Phase-separation Techniques; 2012

Oklahoma State University

The beneficial effects of the consumption of extra virgin olive oils (EVOOs) on human health are well-known and related to the characteristic fatty acid composition, and the presence of minor components, such as phenolic compounds (antioxidant properties). These compounds extend olive oils? shelf life by delaying oxidation reactions and improve some sensory properties including pungency, astringency, bitterness and flavor. Chemically, olive oil consists mainly of glycerols, which account for more than 98% of its total weigh. In addition, it contains about 2% of other, nearly 250 minor components including phenolic compounds. The amounts and composition of these compounds in EVOO depends on several factors such as olive cultivar, degree of maturation and agronomic and technological aspects of production. A simple methodology using dispersive liquid?liquid microextraction (DLLME) combined with CZE has been applied for the simultaneous determination of phenolic compounds of nutraceutic interest (caffeic, gallic, vanillic, syringic, p-coumaric acids and oleuropein, apigenin, luteolin, 3- hydroxytyrosol and tyrosol) in EVOO. The methodology developed shows significant advantages over the low throughput-current methods that use large volumes of organic solvents. Also, the evaporation step is time consuming and may affect the stability of the analytes. On the other hand, trace amounts of analytes cannot be detected due to the small mass used. Optimum DLLME conditions were as follows: extraction of 20 g of EVOO with 300 mL boric acid 30 mM pH= 9.50 and 300 mL carbon tetrachloride, extractant and dispersive solvents, respectively. The BGE that provided complete resolution of the ten analytes was boric acid 30 mM, pH= 9.50. The short time of extraction, centrifugation and electrophoretic steps allow the selective determination of phenolic compounds in oil with satisfactory sensitivities, recoveries and relative standard deviations (RSD), compatible with levels present in the sample. The optimized methodology was applied for the analysis of experimental and commercial EVOOs. The new approach may help for the classification of olive oils according to varietal origin.