Gabriel D. Fernandes

Direct characterization of commercial lecithins by easy ambient sonic-spray ionization mass spectrometry

Commercial lecithins are composed mainly of phospholipids and triacylglycerols. The analysis of the commercial lecithins, including their fraction of phospholipids, normally involves laborious and expensive protocols. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to be an efficient technique for the analysis of lipids. Samples of commercial lecithins including standards, refined, deoiled and modified soy lecithin were tested. Characteristic profiles of phosphatidylcholines and triacylglycerols are detected by EASI(+)-MS, whereas EASI(-)-MS provided phosphatidylethanolamines, glycophospholipids and free fatty acids profiles. Acetylated lecithins also displayed characteristic acetylated derivatives. EASI-MS data was also compared to MALDI-MS, and found to display richer compositional information. The industrial process applied to lecithin fabrication was also characterised via typical EASI-MS profiles. EASI-MS both in its positive and negative ion modes offers a direct, fast and efficient technique able to characterise commercial lecithin.

Rapid fingerprinting of sterols and related compounds in vegetable and animal oils and phytosterol enriched- margarines by transmission mode direct analysis in real time mass spectrometry.

Plant-derived sterols, often referred to as phytosterols, are important constituents of plant membranes where they assist in maintaining phospholipid bilayer stability. Consumption of phytosterols has been suggested to positively affect human health by reducing cholesterol levels in blood via inhibition of its absorption in the small intestine, thus protecting against heart attack and stroke. Sterols are challenging analytes for mass spectrometry, since their low polarity makes them difficult to ionize by both electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI), typically requiring derivatization steps to overcome their low ionization efficiencies. We present a fast and reliable method to characterize the composition of phytosterols in vegetable oils and enriched margarines. The method requires no derivatization steps or sample extraction procedures thanks to the use of transmission mode direct analysis in real time mass spectrometry (TM-DART-MS).

Quantitation of triacylglycerols in vegetable oils and fats by easy ambient sonic-spray ionization mass spectrometry

This innovative mass spectrometric technique provides simple, quick, and reliable quantitative analysis of triacylglycerols in vegetable oils and fats. The easy ambient sonic-spray ionization mass spectrometry (EASI-MS) technique provides simple, quick, and reliable qualitative analysis of triacylglycerols (TAG) in vegetable oils. The use of this ambient mass spectrometry technique, which does not require separation or derivatization before analysis, for precise quantitative analyses has yet to be demonstrated. In this study, the TAG composition of edible vegetable oils, hydrogenated vegetable oils and cocoa butter was quantitated by EASI-MS. The results were compared with those obtained by theoretical predictions of the TAG composition performed by a software projection, which uses a mathematical algorithm of distribution of the fatty acids (FA) in the TAG molecule, and by the direct gas chromatography method (GC-FID). Acceptable correlation coefficients were observed between the three methods during the analysis of vegetable oils and hydrogenated vegetable oils. EASI-MS offers not only simplicity, speed and selectivity for oil analysis but also precise quantitation of the TAG composition. Therefore, EASI-MS is a promising substitute for the more demanding and time-consuming standard protocols, which require separation and sometimes derivatization before analysis.

High throughput MS techniques for caviar lipidomics

The lipid profile of Sturgeon roe (caviar) was monitored by matrix assisted laser desorption/ionization mass spectrometry (MALDI(+)-MS), thermal imprinting easy ambient sonic-spray ionization mass spectrometry (TI-EASI(+)-MS) and electrospray mass spectrometry (ESI(+)-MS). Freshly salted and commercially salted pasteurized caviar samples of Atlantic sturgeon (Acipenser sturio) were stored either at +4 °C or at room temperature for 4 weeks. The different types of chemical information achieved by these MS techniques were compared: MALDI(+)-MS detects mainly phospholipids (PL) whereas TI-EASI(+)-MS allows monitoring of both triacylglycerols (TAG) and PL. ESI(+) coupled to Fourier transform ion cyclotron resonance high resolution mass spectrometer (FT-ICR-MS) and MS/MS experiments were used to fully characterize the detected lipids, ensure the absence of oxidation products in the degradation process and confirm the high efficiency of the thermal imprinting extraction. TI-EASI(+)-MS, via a more comprehensive profiling and easier operation, has therefore been demonstrated to provide caviar lipidomic profiles and discriminate its changes as a function of storage time and temperature. The data have also confirmed that hydrolysis is the main process of lipid degradation in caviar.

Chemical Characterization of Major and Minor Compounds of Nut Oils: Almond, Hazelnut, and Pecan Nut

The aim of this work was to characterize the major and minor compounds of laboratory-extracted and commercial oils from sweet almond, hazelnut, and pecan nut. Oils from sweet almond, hazelnut, and pecan nut were obtained by means of an expeller system, while the corresponding commercial oils were provided from Vital Âtman (BR). The contents of triacylglycerols, fatty acids, aliphatic and terpenic alcohols, desmethyl-, methyl-, and dimethylsterols, squalene, and tocopherols were determined. Oleic, palmitic, and linoleic acids were the main fatty acids. Desmethylsterols were the principal minor compounds with β-sitosterol being the most abundant component. Low amounts of aliphatic and terpenic alcohols were also found. The major tocopherol in hazelnut and sweet almond oils was α-tocopherol, whereas γ-tocopherol prevailed in pecan nut oil. Principal component analysis made it possible for us to differentiate among samples, as well as to distinguish between commercial and laboratory-extracted oils. Heatmap highlighted the main variables featuring each sample. Globally, these results have brought a new approach on nut oil characterization.

Analysis of methanol and ethanol in virgin olive oil

Graphical abstract

TAG, DAG and FFA profiles of dry-cured ham by easy ambient sonic-spray ionization mass spectrometry after thermal imprinting

Espectrometria de massas ambiente com ionizacao por sonic-spray (EASI-MS), uma tecnica de espectrometria de massas ambiente recem desenvolvida, foi diretamente utilizada para a obtencao do perfil de triacilglicerois (TAG), diacilglicerois (DAG) e acidos graxos livres (FFA) em diferentes tipos de presuntos crus curados, apos impressao termica. A tecnica e simples, rapida e confiavel, alem de nao requerer nenhum tipo de hidrolise, derivatizacao ou separacao cromatografica, o que representa vantagens sobre outros procedimentos analiticos normalmente utilizados para este proposito. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS), a recently developed ambient mass spectrometry technique, was used for the direct analysis of triacylglycerols (TAG), diacylglycerols (DAG) and free fatty acids (FFA) in different types of dry-cured ham, after thermal imprinting. The technique is simple, fast and reliable, not requiring hydrolysis, derivatization or chromatographic separation, which represents advantages over other analytical procedures usually used for this purpose.

Desorption/ionization efficiencies of triacylglycerols and phospholipids via EASI-MS

Knowledge of the major effects governing desorption/ionization efficiency is required for the development and application of ambient mass spectrometry. Although all triacylglycerols (TAG) have the same favorable protonation and cationization sites, their desorption/ionization efficiencies can vary dramatically during easy ambient sonic-spray ionization because of structural differences in the carbon chain. To quantify this somewhat surprising and drastic effect, we have performed a systematic investigation of desorption/ionization efficiencies as a function of unsaturation and length for TAG as well as for diacylglycerols, monoacylglycerols and several phospholipids (PL). Affinities for Na(+) as a function of unsaturation level have also been assayed via comprehensive metadynamics calculations to understand the influence of this phenomenon on the ionization efficiency. The results suggest that dipole-dipole interactions within a carbon chain tuned by unsaturation sites govern ionization efficiency of TAG and PL.

Comparative Study of Phytosterol Derivatives in Monovarietal Olive Oils

Plant sterols and their derivatives are minor compounds that have been extensively studied in vegetable oils, mainly in olive oil, where they are closely related with its identity. The objective of this work is to determine the content of free and esterified steryl glucosides and their profiles in olive oil in relation to different geographical situation of olive orchards, cultivar, farming modality, and sampling time. The orchards under study were located in the outer ring of the submetropolitan area of Madrid (Spain), where olives from Cornicabra, Manzanilla Cacereña, Manzanilla Castellana, and Picual varieties were grown under traditional and organic modes, and harvested in four different samplings. Conclusions state that cultivar, farming mode, and light exposure do not have outstanding effects, whereas pedoclimate might affect the steryl glucoside presence in a substantial way. Further studies are being carried out presently in order to confirm such statement. Also glucoside derivative profiles are discussed, and reasons for differences with results in previous studies pointed out.