Direct determination of phenolic secoiridoids in olive oil by ultra-high performance liquid chromatography-triple quadruple mass spectrometry analysis

Abstract

In recent years, a large number of biological properties and an important role in the organoleptic characteristics of olive oil have been attributed to phenolic secoiridoids, such as oleacein, oleocanthal, oleuropein aglycone and ligstroside aglycone. Consequently, quantifying them is of great interest for the olive oil sector. Currently, there is no consensus in which analytical method must be use to accurately determine these compounds in olive oil, mainly owing to the lack of reference standards for calibration. In this work, analytical standards of phenolic secoiridoids have been used to develop a quantitative and rapid analytical method by UHPLC-MS/MS, in which sample extraction is not carried out. Simple dilutions of the sample with dry tetrahydrofuran and dry acetonitrile were performed before analysing them. It is worth noting that under these conditions the generation of artefacts such as acetals and hemiacetals of the aldehydic forms is highly reduced. The detection and quantification was performed with a Xevo TQS tandem quadrupole mass spectrometer. The method was validated at four concentration levels and finally applied to six samples of extra virgin olive oil.

Green Route for the Isolation and Purification of Hyrdoxytyrosol, Tyrosol, Oleacein and Oleocanthal from Extra Virgin Olive Oil

“…Though not of interest in this work, another minor compound eluted at 6.9 min ( Figure 2 ) was detected, and tentatively characterized by means of chromatographic retention factor, UV-visible spectrum and MS spectrum. The compound displays the UV-visible features of EVOO catechols, and an [M−H] − pseudomolecular ion at 377.11 m / z , as reported in the literature for oleuropein aglycone [ 37 , 38 , 39 ]( Figure 5 ).…”

Concentration of Potentially Bioactive Compounds in Italian Extra Virgin Olive Oils from Various Sources by Using LC-MS and Multivariate Data Analysis

“…Oleuropein aglycone was the most common secoiridoid in olive oil ranging from 39.5 to 1785.9 mg kg −1 for EVOOs and from 116.7 to 736.8 mg kg −1 for COOs. These results are in agreement with the outcomes of other authors using Italian and Spanish EVOOs [23,40].…”

“…Ligstroside and oleuropein aglycones and their decarboxymethylated forms, namely oleocanthal (DCL) and oleacin (DCO) are the most common secoiridoids in olive oils. Oleuropein aglycone and oleacin are hydroxytyrosol esters, while the other two are tyrosol derivatives [39,40]. Following the European Union recommendation, secoiridoids are important compounds in the health claim for olive oil [27].…”

Tyrosol and Hydroxytyrosol Determination in Extra Virgin Olive Oil with Direct Liquid Electron Ionization-Tandem Mass Spectrometry

“…Recently, paper spray tandem mass spectrometry was applied to quantify free and total Tyr and Htyr with good results in terms of reliability, rapidity, and sensitivity [35]. Alternatively, EVOO was characterized by the direct determination of the secoiridoids without the hydrolysis of the sample [36].…”