Food quality and authenticity screening via easy ambient sonic-spray ionization mass spectrometry.

This review is the first to summarize a decade of studies testing the use of easy ambient sonic-spray ionization mass spectrometry (EASI-MS) and its several sister techniques, Venturi (V-EASI), thermal imprinting (TI-EASI) and Spartan (S-EASI) mass spectrometry in food quality control and authentication. Since minimal or no sample preparation is required, such ambient desorption/ionization techniques have been shown to provide direct, fast and selective fingerprinting characterization at the molecular level based on the pools of the most typical components. They have also been found to be applicable on intact, undisturbed samples or on simple solvent extracts. Fundamentals of EASI-MS and its sister techniques, including mechanisms, devices, parameters and strategies, as well as the many applications reported for food analysis, are summarized and discussed.

Nanoassisted laser desorption-ionization-MS imaging of tumors.

The ability of nanoassisted laser desorption-ionization mass spectrometry (NALDI-MS) imaging to provide selective chemical monitoring with proper spatial distribution of lipid profiles from tumor tissues after plate imprinting has been tested. NALDI-MS imaging identified and mapped several potential lipid biomarkers in a murine model of melanoma tumor (inoculation of B16/F10 cells). It also confirmed that the in vivo treatment of tumor bearing mice with synthetic supplement containing phosphoethanolamine (PHO-S) promoted an accentuated decrease in relative abundance of the tumor biomarkers. NALDI-MS imaging is a matrix-free LDI protocol based on the selective imprinting of lipids in the NALDI plate followed by the removal of the tissue. It therefore provides good quality and selective chemical images with preservation of spatial distribution and less interference from tissue material. The test case described herein illustrates the potential of chemically selective NALDI-MS imaging for biomarker discovery.

Administration of a murine diet supplemented with conjugated linoleic acid increases the expression and activity of hepatic uncoupling proteins.

Daily intake of conjugated linoleic acid (CLA) has been shown to reduce body fat accumulation and to increase body metabolism; this latter effect has been often associated with the up-regulation of uncoupling proteins (UCPs). Here we addressed the effects of a CLA-supplemented murine diet (~2 % CLA mixture, cis-9, trans-10 and trans-10, cis-12 isomers; 45 % of each isomer on alternating days) on mitochondrial energetics, UCP2 expression/activity in the liver and other associated morphological and functional parameters, in C57BL/6 mice. Diet supplementation with CLA reduced both lipid accumulation in adipose tissues and triacylglycerol plasma levels, but did not augment hepatic lipid storage. Livers of mice fed a diet supplemented with CLA showed high UCP2 mRNA levels and the isolated hepatic mitochondria showed indications of UCP activity: in the presence of guanosine diphosphate, the higher stimulation of respiration promoted by linoleic acid in mitochondria from the CLA mice was almost completely reduced to the level of the stimulation from the control mice. Despite the increased generation of reactive oxygen species through oxi-reduction reactions involving NAD(+)/NADH in the Krebs cycle, no oxidative stress was observed in the liver. In addition, in the absence of free fatty acids, basal respiration rates and the phosphorylating efficiency of mitochondria were preserved. These results indicate a beneficial and secure dose of CLA for diet supplementation in mice, which induces UCP2 overexpression and UCP activity in mitochondria while preserving the lipid composition and redox state of the liver.

Distinct hepatic lipid profile of hypertriglyceridemic mice determined by easy ambient sonic-spray ionization mass spectrometry.

Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) was used to interrogate the hepatic lipid profiles of hypertriglyceridemic and control normotriglyceridemic mice. The analyses of ex vivo complex lipid mixtures were made directly with EASI-MS without accompanying separation steps. Intense ions for phosphatidylcholines and triacylglycerols were observed in the positive ion mode whereas the spectra in the negative ion mode provided profiles of phosphatidylethanolamines and phosphatidylinositol. EASI-MS was coupled to high-performance thin-layer chromatography for analysis of free fatty acids. Fourier transform-ion cyclotron resonance-mass spectrometry was also employed to confirm the identity of the detected lipids. We demonstrated higher incorporation of oleic acid in phosphatidylcholine and triacylglycerol composition, higher relative abundance of arachidonic acid containing phosphatidylinositol, and overall distinct free fatty acid profile in the livers of genetic hypertriglyceridemic mice. We propose that these alterations in liver lipid composition are related to the higher tissue and body metabolic rates described in these hypertriglyceridemic mice.

Instantaneous characterization of vegetable oils via TAG and FFA profiles by easy ambient sonic-spray ionization mass spectrometry.

A fast and reliable method is presented for the analysis of vegetable oils. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to efficiently desorb and ionize the main oil constituents from an inert surface under ambient conditions and to provide comprehensive triacylglyceride (TAG) and free fatty acid (FFA) profiles detected mainly as either [TAG + Na](+) or [FFA-H](-) ions. EASI(+/-)-MS analysis is simple, easily implemented, requires just a tiny droplet of the oil and is performed without any pre-separation or chemical manipulation. It also causes no fragmentation of TAG ions hence diacylglyceride (DAG) and monoacylglyceride (MAG) profiles and contents can also be measured. The EASI(+/-)-MS profiles of TAG and FFA permit authentication and quality control and can be used, for instance, to access levels of adulteration, acidity, oxidation or hydrolysis of vegetable oils in general.

Ambient mass spectrometry: bringing MS into the "real world".

Mass spectrometry has recently undergone a second contemporary revolution with the introduction of a new group of desorption/ionization (DI) techniques known collectively as ambient mass spectrometry. Performed in an open atmosphere directly on samples in their natural environments or matrices, or by using auxiliary surfaces, ambient mass spectrometry (MS) has greatly simplified and increased the speed of MS analysis. Since its debut in 2004 there has been explosive growth in the applications and variants of ambient MS, and a very comprehensive set of techniques based on different desorption and ionization mechanisms is now available. Most types of molecules with a large range of masses and polarities can be ionized with great ease and simplicity with the outstanding combination of the speed, selectivity, and sensitivity of MS detection. This review describes and compares the basis of ionization and the concepts of the most promising ambient MS techniques known to date and illustrates, via typical analytical and bioanalytical applications, how ambient MS is helping to bring MS analysis deeper than ever into the "real world" open atmosphere environment--to wherever MS is needed.

Assessing the Metabolic Impact of Ground Chia Seed in Overweight and Obese Prepubescent Children: Results of a Double-Blind Randomized Clinical Trial.

Childhood obesity is a medical condition of major public health concern. Chia seeds are used to treat certain noncommunicable diseases, and they are rich in omega-3 fatty acids, which contribute to the absorption of vitamins. A randomized double-blind clinical trial of 30 obese children was performed. The sample was composed of prepubertal 5- to 10-year-old children of both sexes with body mass indexes equal to or above the 95th percentile who were recruited through the Pediatric Department of the Faculdade de Medicina do ABC. Blood samples were drawn, the children were weighed and measured, and a 24-h dietary recall was obtained before and after the treatment. Not only were significant differences observed for fibrinogen (P = .011) but a correlation between the changes in markers and the presence of fibers was also observed for two inflammatory parameters: tumor necrosis factor-α (P = .027) and nuclear factor-κß (P = .059). These results indicate that chia seeds may have anti-inflammatory effects related to their fiber content in the context of childhood obesity.

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).

Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station.

Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 µm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices. Graphical Abstract ᅟ.

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.

Brazil nut oil: quality control via triacylglycerol profiles provided by easy ambient sonic-spray ionization mass spectrometry.

Brazil nut oil is one of the important Amazonian natural products in the global market. Despite its health benefits and applications in food and cosmetic industries, authentication and quality control of the oil are far from satisfactory. Several samples of Amazonian Brazil nut oil (authentic oils of different geographic origins, commercial oils, and oils adulterated with soybean oil) were evaluated by easy ambient sonic-spray ionization mass spectrometry (EASI-MS). The samples were characterized on the basis of triacylglycerol profiles, and their major ions were subjected to chemometric treatment (principal component analysis). The ambient mass spectrometry analysis and the set of major ions allowed the characterization of authentic oils, commercial oils, and adulterated oils (5% soybean oil) in a few minutes and without sample preparation. Therefore, it is shown that quality control of Amazonian vegetable oils can be readily accomplished by EASI-MS.

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.

Natural and artificial markers of gasoline detected by membrane introduction mass spectrometry.

A few hydrocarbons in gasoline display relatively high solubility in water and may function therefore as its characteristic set of natural markers. These markers are detected from an aqueous gasoline extract via membrane introduction mass spectrometry (MIMS) producing characteristic chemical profiles. MIMS adds a second selectivity criterion detecting only the water soluble hydrocarbons that most easily permeate through a silicone membrane. MIMS screening and the use of artificial markers for gasoline with similar chemical properties (high water solubility and membrane permeability) as those of its natural markers is proposed. MIMS provides a reliable screening method for natural and artificial markers in gasoline for its typification and to monitor adulteration and origin.

Analysis of fuels via easy ambient sonic-spray ionization mass spectrometry.

The desorption and ionization of analytes directly from surfaces or natural matrices under ambient conditions has greatly simplified chemical analysis by mass spectrometry. Among the currently available set of such techniques, easy ambient sonic-spray ionization (EASI) is one of the simplest and most easily implemented. Fuels are among the most important and most complex classes of chemical mixtures and a challenge for fast and comprehensive chemical analysis. This review summarizes the applications of EASI-MS for fast, simple and nearly sample-preparation-free analysis of various fuels, focusing in typification, adulteration and quality control.

Quantitation of trace phenolic compounds in water by trap-and-release membrane introduction mass spectrometry after acetylation.

Trap-and-release membrane introduction mass spectrometry (T&R-MIMS) with a removable direct insertion membrane probe (DIMP) is used to quantitate a variety of trace phenolic compounds in water after acetylation. The procedure is simple, rapid and robust, producing linear and reproducible responses for phenolic compounds with varying polarities. Acetylation minimizes the polarity effects of ring substituents; hence, T&R-MIMS of the acetylated phenols provides lower and more uniform limits of detection (LODs) (2-15 microg L(-1)) than those obtained by direct T&R-MIMS analysis of the non-derivatized phenols.

Heterogenous photocatalysis: an emerging technology for remediation of VOC contaminated environments

Heterogeneous photocatalysis has been studied in the last two decades for the treatment of contaminated water and wastewaters, and more recently, in the clean up process of contaminated atmosphere. Scientific principles of the method and a survey of the recent literature for aqueous and gas-phase photocatalytic oxidation of volatile organic compounds (VOCs) are presented. The influence of different parameters, types of photoreactors and kinetics of photodegradation are discussed.