Evaluating the potential of LC coupled to three alternative detection systems (ESI-IT, APCI-TOF and DAD) for the targeted determination of triterpenic acids and dialcohols in olive tissues

Abstract

Herewith the development of a rapid and powerful LC methodology (with three different detectors) is presented to determine triterpenic acids and dialcohols in extracts from Olea europaea tissues (olive skin, pulp and leaves). After the proper optimization of the LC, DAD and MS conditions (and the comprehensive characterization of the behaviour of each analyte in ESI and APCI (with accurate m/z signals and, in ESI, with MS/MS data too), the method was fully validated. DAD, ESI-IT MS and APCI-QTOF MS were used as detection systems to give different alternatives to carry out the accurate determination of these analytes, evaluate their analytical performance, advantages and drawbacks, and check whether the quantitative results achieved by the three platforms were in good agreement. ESI-IT MS gave the lowest detection limits (3-455 μg/L) followed by APCI-QTOF MS (22-408 μg/L); in contrast, DAD (83-600 μg/L) had the widest dynamic range. The RSD values for inter-day repeatability were found below 11.82 % in all the cases. No statistically significant differences were found among the quantitative results from the three detectors. Olive leaves showed the highest concentration levels of ursolic acid (1.8 mg/g), erythrodiol (1.6 mg/g) and uvaol (1.2 mg/g), whereas the olive skin was the richest matrix in terms of maslinic (80 mg/g), betulinic (0.20 mg/g), and oleanolic (26 mg/g) acids. Concentration values of triterpenic acids were established by first time for skinless olive pulp, and were found around 65, 1.2, 55 and 4.4 μg/g for maslinic, betulinic, oleanolic and ursolic acids, respectively.