Accurate determination of phenolic compounds from extra virgin olive oil by direct injection of the diluted samples into a LC-MS system: no need of applying any extraction protocol

OLMO-GARCÍA, LUCÍA; BAJOUB, AADIL; MONASTERIO, ROMINA P.; CARRASCO-PANCORBO, ALEGRÍA; FERNÁNDEZ-GUTIÉRREZ, ALBERTO

Estocolmo

Encuentro; XIX Euroanalysis 2017, Europe's Analytical Chemistry Meeting; 2017

Europe's Analytical Chemistry Meeting

A LC-MS method involving direct injection of extra-virgin olive oil (EVOO) -after a simple dilution- for determining its phenolic compounds has been developed. The most appropriate solvent for sample dilution had to be chosen, as well as the optimum oil/solvent ratio. It was also necessary to develop a column cleaning strategy and establish the maximum number of injections to be carried out before routine cleanings. Then, the analytical parameters of the method were evaluated, establishing LOD (from 3.3 to 31.6 µg/L) and LOQ, precision (RSD values for inter-day repeatability were found between 3.49 and 6.12%), and trueness (within the range 89.9-102.3% for 1.0 mg/L) and checking possible matrix effect (which was no significant). Three kinds of calibration were used: external standard, standard addition and calibration in a phenols-free matrix, which was subsequently applied to quantify the phenolic compounds in 16 EVOOs (from 6 cultivars). A total of 21 compounds were determined without the need of using any extraction protocol. Apart from time saving, the greatest advantages of the implementation of the VOO direct injection into the LC (after a simple dilution) are the prevention of partial and selective recovery of some phenolic compounds after the extraction and their possible partial oxidation, or the creation of artificial isomers during the sample preparation.