Simultaneous analysis of natural pigments and E-141i in olive oils by liquid chromatography–tandem mass spectrometry

Abstract

This work describes the development of an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of carotenoids (ß-carotene, lutein, ß-criptoxanthin, neoxanthin, violaxanthin) and chlorophylls, as well as their related compounds (chlorophyll A and B, pheophytin A and B and the banned dyes Cu-pyropheophytin A, Cu-pheophytin A and B) in olive oils. For this purpose, the feasibility of electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the ionization of these compounds was evaluated and compared. Tandem mass spectrometry (MS/MS) fragmentation was discussed for each family of compounds and the most characteristic and abundant product ions were selected to propose a selective and sensitive UHPLC-MS/MS method. The best results were obtained using APCI and APPI, while ESI provided the worst signal-to-noise ratio (S/N) for all compounds. For the analysis of olive oils, a simple solid phase extraction (SPE) with silica cartridges was applied before the determination by UHPLC-MS/MS (APCI and APPI) in multiple reaction monitoring (MRM) mode. Method quality parameters were stablished and the results demonstrate the good performance of the new methods, providing low limits of detection (0.004 -0.9 mg L-1), high extraction efficiencies (62 − 95%) and low matrix effects (<25%). The developed UHPLC-API-MS/MS (APCI and APPI) methods were applied to the analysis of olive oil samples and ß-carotene, pheophytin A, pheophytin B and lutein were detected and quantified in all of them at concentrations ranging from 0.1 to 9.5 mg L-1.

Importance of some minor compounds in olive oil authenticity and quality

“…The artificial neural networks applied to visible spectroscopic data could be used to determine varietal quantifications based on the pigment profile of monovarietal extra virgin olive oils at 10% and 2.8% for the linear and non-linear models, respectively Aroca-Santosa, Cancilla, Pérez-Pérez, Moral, and Torrecilla (2016) Detection of possible fraud markers Ultra-high-performance liquid chromatography tandem mass spectrometry coupled with two types of atmospheric pressure ionizations (chemical and photoionization) were found efficient in determining natural color pigments (carotenoids, chlorophylls and chlorophyll derivatives) as well as artificial ones (E141i) in olive oils. These methods were applicable in pigment profile identification as well as the detection of possible exogenous adulterants Arrizabalaga-Larrañaga, Rodríguez, Medina, Santos, and Moyano (2019) Cultivar differentiation Five different Greek olive oil cultivars were successfully characterized and classified based on acidity, total chlorophylls and carotenoids, myristic, margaric, stearic, arachidic, and eicosenoic acids at a rate of 91.9% and 81.1% by using original and cross-validation methods, respectively Karabagias et al (2019) Geographical differentiation Geographical discrimination power of several chemical parameters (total phenol content, fatty acid and phenol profile, total carotene and chlorophyll content and oxidative stability) and mid-infrared spectroscopy on olive oils was investigated. It was found that combination of chemical parameters was better than mid-IR spectroscopy in classification of monovarietal olive oil obtained from geographically close regions of Turkey Uncu and Ozen (2016) Cultivar discrimination Monovarietal extra virgin olive oils could be classified up to 94.4% according to their variety by using Raman spectroscopy highly correlated with both carotenoid and fatty acid composition of olive oils.…”

Determination of capsaicinoids and carotenoids for the characterization and geographical origin authentication of paprika by UHPLC–APCI–HRMS

“…The chromatographic separation of all target compounds was performed in a reversed-phase UHPLC Accucore C18 column, under a quaternary gradient elution with water, methanol, acetonitrile, and acetone as the mobile phase components. The gradient elution was based on a chromatographic method previously developed for the separation of chlorophylls and carotenoids (Arrizabalaga-Larrañaga, Rodríguez, Medina, Santos, & Moyano, 2019). However, some modifications were required to deal with the simultaneous determination of capsaicinoids and carotenoids.…”

Development of an accurate and direct method for the green food colorants detection

“…As a consequence of the isotope profile of copper, the isotopic distribution of copper chlorophyll derivatives ( Figure 2) shows an isotopic pattern that resembles the significant abundance of Cu 64.9272 (44.6%) to the isotope pattern of copper. As an example, Figure 2A displays the isotopic pattern of copper pyropheophytin a (C 53 H 70 CuN 4 O 3 ), the main chlorophyll derivative in lipophilic green food colorants (E-141i) (Roca et al, 2010;Fang et al, 2015;Arrizabalaga-Larrañaga, Rodríguez, Medina, Santos, & Moyano, 2019), which was calculated with the Compass Isotope Pattern software (section 2.3). For this copper chlorophyll compound, the abundance of the third isotope is higher (0.62747) than the second one (0.59716), as can be confirmed in Figure 3A with the authentic standard of copper pyropheophytin a.…”