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Schistosomiasis is a parasitic infection which affects more than 200 million people globally.Metabolic reprogramming was analyzed by matrix-assisted laser desorption/ionization mass spectrometry imaging, liquid chromatography with high-resolution mass spectrometry, metabolite quantification, confocal laser scanning microscopy, live cell imaging, quantitative real-time PCR, western blotting, assessment of DNA damage, and immunohistology in hamster models and functional experiments in human cell lines. Major results were validated in human biopsies.The infection withOur findings indicate thatThe authors demonstrate that soluble egg products of the parasite

The obligate intracellular apicomplexan parasites Toxoplasma gondii and Besnoitia besnoiti are important causes of disease in both humans and cattle. To date, effective specific treatments are lacking for both infections. To counteract severe symptoms leading to, e.g., disabilities and even abortion in the case of human toxoplasmosis and bovine besnoitiosis, novel targets are required for development of drugs and vaccines. A promising emerging technique for molecular characterization of organisms is high-resolution atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization (AP-SMALDI) mass spectrometry imaging (MSI) which enables semiquantitative visualization of metabolite distributions. MSI was here used to trace and characterize lipid metabolites in primary bovine umbilical vein endothelial cells (BUVECs) upon infection with tachyzoites, an early and pathogenic fast-replicating life stage of T. gondii and B. besnoiti. A cell bulk, derived from noninfected controls and parasite-infected cell pellets, was analyzed by AP-SMALDI MSI in technical and biological triplicates. Multivariate statistical analysis including hierarchical clustering and principle component analysis revealed infection-specific metabolites in both positive- and negative-ion mode, identified by combining database search and LC-MS2 experiments. MSI analyses of host cell monolayers were conducted at 5 μm lateral resolution, allowing single apicomplexan-infected cells to be allocated. This is the first mass spectrometry imaging study on intracellular T. gondii and B. besnoiti infections and the first detailed metabolomic characterization of B. besnoiti tachyzoites. MSI was used here as an efficient tool to discriminate infected from noninfected cells at the single-cell level in vitro.

The distribution of atherosclerotic lesions in the aorta and its branches of ApoE knockout (ApoE−/−) mice is like that of patients with atherosclerosis. By using high-resolution MALDI mass spectrometry imaging (MSI), we aimed at characterizing universally applicable physiological biomarkers by comparing the murine lipid marker profile with that of human atherosclerotic arteries. Therefore, the aorta or carotid artery of male ApoE−/− mice at different ages, human arteries with documented atherosclerotic changes originated from amputated limbs, and corresponding controls were analysed. Obtained data were subjected to multivariate statistical analysis to identify potential biomarkers. Thirty-one m/z values corresponding to individual lipid species of cholesterol esters, lysophosphatidylcholines, lysophosphatidylethanolamines, and cholesterol derivatives were found to be specific in aortic atherosclerotic plaques of old ApoE−/− mice. The lipid composition at related vessel positions of young ApoE−/− mice was more comparable with wild-type mice. Twenty-six m/z values of the murine lipid markers were found in human atherosclerotic peripheral arteries but also control vessels and showed a more patient-dependent diverse distribution. Extensive data analysis without marker preselection based on mouse data revealed lysophosphatidylcholine and glucosylated cholesterol species, the latter not being detected in the murine atherosclerotic tissue, as specific potential novel human atherosclerotic vessel markers. Despite the heterogeneous lipid profile of atherosclerotic peripheral arteries derived from human patients, we identified lipids specifically colocalized to atherosclerotic human tissue and plaques in ApoE−/− mice. These data highlight species-dependent differences in lipid profiles between peripheral artery disease and aortic atherosclerosis.

Schistosomiasis, caused by the human parasiteSchistosoma mansoni, is one of the WHO-listed neglected tropical diseases (NTDs), and it has severe impact on morbidity and mortality, especially in Africa. Not only the adult worms but also their eggs are responsible for health problems. Up to 50% of the eggs produced by the female worms are not excreted with the feces but are trapped in the host tissue, such as the liver, where they provoke immune responses and a change in the lipid profile. We built up a database with 372 infection markers found in livers ofS. mansoni-infected hamsters, using LC–MS/MS for identification, followed by statistical analysis. Most of them belong to the lipid classes of phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and triglycerides (TGs). We assigned some of these markers to specific anatomical structures by applying high-resolution MALDI MSI to cryosections of hamster liver and generating ion images based on the marker list from the LC–MS/MS experiments. Furthermore, enrichment and depletion of several markers were visualized.Graphic Abstract

Schistosoma mansoni is a parasitic flatworm causing schistosomiasis, an infectious disease affecting several hundred million people worldwide. Schistosomes live dioeciously, and upon pairing with the male, the female starts massive egg production, which causes pathology. Praziquantel (PZQ) is the only drug used, but it has an inherent risk of resistance development. Therefore, alternatives are needed. In the context of drug repurposing, the cancer drug imatinib was tested, showing high efficacy against S. mansoni in vitro. Besides the gonads, imatinib mainly affected the integrity of the intestine in males and females. In this study, we investigated the potential uptake and distribution of imatinib in adult schistosomes including its distribution kinetics. To this end, we applied for the first time atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) for drug imaging in paired S. mansoni. Our results indicate that imatinib was present in the esophagus and intestine of the male as early as 20 min after in vitro exposure, suggesting an oral uptake route. After one hour, the drug was also found inside the paired female. The detection of the main metabolite, N-desmethyl imatinib, indicated metabolization of the drug. Additionally, a marker signal for the female ovary was successfully applied to facilitate further conclusions regarding organ tropism of imatinib. Our results demonstrate that AP-SMALDI MSI is a useful method to study the uptake, tissue distribution, and metabolization of imatinib in S. mansoni. The results suggest using AP-SMALDI MSI also for investigating other antiparasitic compounds and their metabolites in schistosomes and other parasites. Graphical abstract

The obligate intracellular apicomplexan parasites

A general-purpose desorption electrospray ionization (DESI) source is presented which is not bound to the laboratory site. It allows autarkic operation for a few hours and can be connected to different types of (autarkic or non-autarkic) mass spectrometers via an atmospheric-pressure interface. Technical characteristics are described as well as results from direct surface analysis of consumer goods such as plastics, fruit peels or pills, or from living objects such as human skin, demonstrating the detection of various target compounds such as plasticizers, pesticides, drugs or sun blockers. Quantitative analysis is demonstrated for phthalates in plastics. The geometry of the sample, the sample table and the sprayer were modified and characterized for optimization of the method. The autarkic ion source has a total size of 48.4 × 27.0 × 18.0 cm (l × w × h) and a total mass of 7 kg. The source delivers 5.5 bar pressurized air and an adjustable solvent flow rate down to 1.5 μl min−1 for the DESI sprayer. A rechargeable 25.6 V battery allows autarkic runtimes of more than 3.5 hours. Source optimization and characterization was done on an orbital trapping mass spectrometer. Connected to a portable mass spectrometer, the developed device makes DESI suitable for on-site analyses in e.g. consumer protection, border control or homeland security.

Ambient ionization techniques are typically used to analyze samples in their native states with minimal or no sample pretreatment prior to mass spectrometric (MS) analysis. Desorption electrospray ionization (DESI) and direct analysis in real time (DART) were systematically investigated in this work for direct solid analysis of depolymerized lignin samples, with the goal of rapidly fingerprinting these samples, to efficiently characterize the subunits of this renewable energy source. High resolution MS was required for enhanced selectivity in this study due to the inherent structural complexity of lignin. DESI provided results across a broader mass range (up to m/z 700) than DART and also ionized saturated compounds of low oxygen-to-carbon (O/C) ratios and low double bond equivalents (DBE). While DART detected the same core lignin monomeric and dimeric compounds as seen with DESI and electrospray ionization (ESI), results were restricted to a narrower mass range to m/z 500, due to thermal degradation and losses of methoxy groups. In contrast to DESI and ESI, the DART spectra were nearly void of saturated components. On a structural level, the core lignin compounds were visually fingerprinted and ionization method performances critically assessed by employing simplified Kendrick-based data mining approaches. A novel simplified data visualization approach was developed in this work based on modified Kendrick mass defect (KMD) filtering for lignin subunits and plotting the mass defect values against the degree of unsaturation. Direct visualization of monomeric, dimeric and trimeric lignin species was simplified by the KMD separation plots, easily allowing the core lignin compounds to be visually identified and compared. Modified KMD bases, namely methoxy and phenol bases, which represent monomer-specific lignin constituents, were successfully used to classify and group the complex mixture of lignin species. Further separation of methoxy-related lignin species was successfully achieved by employing the more specific phenolic KMD base.

Direct analysis of fruit and vegetable surfaces is an important tool for in situ detection of food contaminants such as pesticides. We tested three different ways to prepare samples for the qualitative desorption electrospray ionization mass spectrometry (DESI-MS) analysis of 32 pesticides found on nine authentic fruits collected from food control. Best recovery rates for topically applied pesticides (88%) were found by analyzing the surface of a glass slide which had been rubbed against the surface of the food. Pesticide concentration in all samples was at or below the maximum residue level allowed. In addition to the high sensitivity of the method for qualitative analysis, quantitative or, at least, semi-quantitative information is needed in food control. We developed a DESI-MS method for the simultaneous determination of linear calibration curves of multiple pesticides of the same chemical class using normalization to one internal standard (ISTD). The method was first optimized for food extracts and subsequently evaluated for the quantification of pesticides in three authentic food extracts. Next, pesticides and the ISTD were applied directly onto food surfaces, and the corresponding calibration curves were obtained. The determination of linear calibration curves was still feasible, as demonstrated for three different food surfaces. This proof-of-principle method was used to simultaneously quantify two pesticides on an authentic sample, showing that the method developed could serve as a fast and simple preselective tool for disclosure of pesticide regulation violations. Graphical Abstract Multiple pesticide residues were detected and quantified in-situ from an authentic set of food items and extracts in a proof of principle study.

Background and Purpose The colonic surface epithelium produces acetylcholine, released after the binding of propionate to GPCRs for this short-chain fatty acid (SCFA). This epithelial acetylcholine then induces anion secretion via stimulation of acetylcholine receptors. The key enzyme responsible for acetylcholine synthesis, choline acetyltransferase, is known to be unselective as regards the fatty acid used for esterification of choline. As the colonic epithelium is permanently exposed to high concentrations of different SCFAs produced by bacterial fermentation, we investigated whether choline esters other than acetylcholine, propionylcholine and butyrylcholine, are produced by the colonic epithelium, too, and whether these ‘atypical’ esters are able to stimulate the acetylcholine receptors involved in the regulation of colonic ion transport. Experimental Approach Desorption electrospray ionization mass spectroscopy (DESI-MS), Ussing chamber and Ca2+-imaging experiments were performed on rat distal colon. Key Results DESI-MS analyses revealed the production of acetylcholine, propionylcholine and butyrylcholine in the surface epithelium. Relative expression rates were 2–3% in comparison with acetylcholine. In Ussing chamber experiments, both atypical choline esters caused a concentration-dependent increase in short-circuit current, that is, stimulated anion secretion. Inhibitor experiments in the absence and presence of the submucosal plexus revealed the involvement of neuronal and epithelial acetylcholine receptors. While butyrylcholine obviously stimulated both nicotinic and muscarinic receptors, propionylcholine predominantly acted on muscarinic receptors. Conclusions and Implications These results suggest a novel pathway for communication between intestinal microbes producing SCFA and the host via modification of epithelial production of choline esters involved in the paracrine regulation of the colonic epithelium.

Schistosomes are parasitic platyhelminthes that cause schistosomiasis, which is a life-threatening infectious disease for humans in the tropics and subtropics worldwide. Within the human host, female and male schistosomes develop and pair as a prerequisite for egg production. Part of the eggs get lodged in organs such as the gut, spleen, and liver, where they cause severe inflammatory processes, including liver fibrosis, which is one of the most serious pathological symptoms. High-resolution atmospheric-pressure scanning microprobe matrix-assisted laser desorption/ionization (AP-SMALDI) mass spectrometry imaging (MSI) has been used as a powerful tool to investigate adult schistosomes at the topographic molecular level. An MSI-compatible protocol was developed, covering critical sample preparation steps and focusing on obtaining artifact-free, longitudinal cryosections. Planar, consecutive sections were prepared from ∼400 μm thick S. mansoni worm couples, comparing several microembedding approaches. High-resolution MSI at both, 10 and 5 μm lateral resolution unraveled anatomical structures and differential abundances of glycerophospholipids and saccharides in females and males. In addition, glycerophospholipids occurred differentially abundant in worm tissues of the female, such as the gut, which is essential for nutrient uptake and subsequent metabolism. Fragment ions of isobaric phospholipids were investigated by on-tissue MS

Acetylcholine and atypical esters of choline such as propionyl- and butyrylcholine are produced by the colonic epithelium and are released when epithelial receptors for short-chain fatty acids (SCFA) are stimulated by propionate. It is assumed that the SCFA used by the choline acetyltransferase (ChAT), the central enzyme for the production of these choline esters, originate from the colonic lumen, where they are synthesized during the bacterial fermentation of carbohydrates. Therefore, it seemed to be of interest to study whether the non-neuronal cholinergic system in the colonic epithelium is affected by maneuvers intended to stimulate or to inhibit colonic fermentation by changing the intestinal microbiota. In two series of experiments, rats were either fed with a high fiber diet (15.5% (w/v) crude fibers in comparison to 4.6% (w/w) in the control diet) or treated orally with the antibiotic vancomycin. High fiber diet induced an unexpected decrease in the luminal concentration of SCFA in the colon, but an increase in the caecum, suggesting an upregulation of colonic SCFA absorption, whereas vancomycin treatment resulted in the expected strong reduction of SCFA concentration in colon and caecum. MALDI MS analysis revealed a decrease in the colonic content of propionylcholine by high fiber diet and by vancomycin. High fiber diet caused a significant downregulation of ChAT expression on protein and mRNA level. Despite a modest increase in tissue conductance during the high fiber diet, main barrier and transport properties of the epithelium such as basal short-circuit current (Isc), the flux of the paracellularly transported marker, fluorescein, or the Isc induced by epithelial acetylcholine release evoked by propionate remained unaltered. These results suggest a remarkable stability of the non-neuronal cholinergic system in colonic epithelium against changes in the luminal environment underlying its biological importance for intestinal homeostasis.

Macrophages are large phagocytes playing a crucial role in the development and progression of atherosclerosis. The phenotypic polarization and activation of macrophages in atherosclerotic plaques depends on their complex micro-environment and at the same time has a major impact on the vulnerability or stability of advanced atherosclerotic lesions. Many in vitro and in vivo studies have been designed to define markers for macrophage subtypes to better understand the mechanism of plaque progression but they have rather added to the confusion. Nonetheless, some of the in vitro defined macrophage subtypes, like the pro-inflammatory M1 or the anti-inflammatory M2a/b/c macrophage, have been shown to be present in atherosclerotic plaques. Herein, we developed a comprehensive workflow to distinguish between human in vitro differentiated pro-inflammatory M1 and anti-inflammatory M2a and M2c macrophages. The cells were analyzed using qPCR and FACS analyses for defining suitable markers on the transcript (mRNA) and protein level as well as MALDI MSI for the assignment of metabolic markers, which can be used for the identification of the corresponding macrophage subtypes in atherosclerotic plaques. Data obtained using both qPCR and FACS analyses were in agreement with the literature. For the analysis of the macrophages with MALDI MSI, a comprehensive workflow was developed and the obtained data were subjected to different statistical analysis methods like principal component analysis (PCA) to define markers for each macrophage type. Our MALDI MSI results revealed that the method produces reliable and reproducible results but that the heterogeneity of the monocytes derived from different donors is too high to define universal markers on the metabolic level. Moreover, the results show that a sample set of three biological replicates is not sufficient to obtain representative data and therefore we recommend performing ring experiments in which the samples are measured by different laboratories.

Distribution of pesticides both on the surface of leaves and in cross sections of plant stem and leaves was investigated using desorption electrospray ionization mass spectrometry imaging (DESI-MSI) with a spatial resolution of 50-100 μm. Two commercially available insecticide sprays containing different contact pesticides were applied onto leaves of Cotoneaster horizontalis, and the distributions of all active ingredients were directly analyzed. The first spray contained pyrethrins and rapeseed oil, both known as natural insecticides. Each component showed an inhomogeneous spreading throughout the leaf, based on substance polarity and solubility. The second spray contained the synthetic insecticides imidacloprid and methiocarb. Imidacloprid accumulated on the border of the leaf, while methiocarb was distributed more homogenously. In order to investigate the incorporation of a systemically acting pesticide into Kalanchoe blossfeldiana, a commercially available insecticide tablet containing dimethoate was spiked to the soil of the plant. Cross sections of the stem and leaf were obtained 25 and 60 days after application. Dimethoate was mainly detected in the transport system of the plant after 25 days, while it was found to be homogenously distributed in a leaf section after 60 days.

Phthalates are used as plasticizes in many everyday items, but some of them are known as hormone disruptors, being especially harmful during childhood. The European Union therefore restricted their application in children's toys and certain food packaging to 0.1%w. Due to the ever increasing number of plastic-containing consumer goods, rapid screening methods are needed to ensure and improve consumer safety in the future. In this study we evaluated the performance of desorption electrospray ionization (DESI) mass spectrometry (MS) for rapid quantitative screening of phthalates in toys. DESI allowed for direct surface sampling of the toys under atmospheric conditions with minimal sample preparation, while the high performance mass spectrometer used provided a high sensitivity and reliable identification via accurate mass measurements, high mass resolving power and MS/MS capabilities. External calibration curves for six banned phthalates (DBP, BBP, DEHP, DNOP, DINP and DIDP) were obtained from matrix-matched reference materials. Coefficients of determination were greater than 0.985, LOQs ranged from 0.02%w (DIDP) to 2.26%w (DINP) and the relative standard deviation of the calibration curve slope was less than 7.8% for intraday and 11.4% for interday comparison. The phthalate contents of eleven authentic samples were determined in a proof-of-concept approach using DESI MS and results were compared to those from confirmatory methods. The phthalate content was correctly assigned with relative deviations ranging from -20% to +10% for the majority of samples. Given further optimization and automation, DESI MS is likely to become a useful tool for rapid and accurate phthalate screening in the future.

Food adulteration is a threat to public health and the economy. In order to determine food adulteration efficiently, rapid and easy-to-use on-site analytical methods are needed. In this study, a miniaturized mass spectrometer in combination with three ambient ionization methods was used for food authentication. The chemical fingerprints of three milk types, five fish species, and two coffee types were measured using electrospray ionization, desorption electrospray ionization, and low temperature plasma ionization. Minimum sample preparation was needed for the analysis of liquid and solid food samples. Mass spectrometric data was processed using the laboratory-built software MS food classifier, which allows for the definition of specific food profiles from reference data sets using multivariate statistical methods and the subsequent classification of unknown data. Applicability of the obtained mass spectrometric fingerprints for food authentication was evaluated using different data processing methods, leave-10%-out cross-validation, and real-time classification of new data. Classification accuracy of 100% was achieved for the differentiation of milk types and fish species, and a classification accuracy of 96.4% was achieved for coffee types in cross-validation experiments. Measurement of two milk mixtures yielded correct classification of94%. For real-time classification, the accuracies were comparable. Functionality of the software program and its performance is described. Processing time for a reference data set and a newly acquired spectrum was found to be 12 s and 2 s, respectively. These proof-of-principle experiments show that the combination of a miniaturized mass spectrometer, ambient ionization, and statistical analysis is suitable for on-site real-time food authentication.

Organic UV filters in personal care products (PCPs) have been persistently reported as a potential threat to human health. In order to guarantee consumers ’ safety, the dose of these compounds in PCPs needs to be monitored. Here, a methodology based on reactive low temperature plasma ionization (LTP) mass spectrometry (MS) has been developed for the determination of common organic UV filters in PCPs including benzophenone-3, ethylhexyl dimethyl p-aminobenzoic acid, ethylhexyl methoxycinnamate, 4-methylbenzylidene camphor, octocrylene, and ethylhexyl salicylate. The experiments were carried out in transmission geometry where the LTP ion source, samples loaded on a stainless steel mesh, and the MS inlet were aligned coaxially. Four chemicals, ammonia, ammonium formate, aniline, and methylamine were considered as reactive additives allowing reactions with the UV filters through different mechanisms. Methylamine-induced reactive LTP-MS showed the most prominent improvement on the detection of UV filter compounds. Compared to direct LTP-MS, the developed method improved the detection limits of UV filters more than 10 fold. Moreover, the method enabled fast semi-quantitative screening of UV filters in authentic PCPs. Concentrations of active ingredients in eight authentic PCPs as determined with reactive LTP-MS were found comparable to values offered by the cosmetic companies and corresponding HPLC data. The methodology provides high throughput analysis (70 s per sample) and sensitive identification of organic UV filters. Lowest detectable concentrations ranged from 0.13 µg/g for 4-methylbenzylidene camphor to 7.67 µg/g for octocrylene in spiked cream. In addition, it shows the potential to be used as a screening tool for legal authentications of these chemicals in the future due to its semi-quantitative determination of UV filters in PCPs without tedious sample preparation and time-consuming chromatographic separation.

BACKGROUND AND PURPOSE Recent studies detected the expression of proteins involved in cholinergic metabolism in airway epithelial cells, although the function of this non-neuronal cholinergic system is not known in detail. Thus, this study focused on the effect of luminal ACh as a regulator of transepithelial ion transport in epithelial cells. EXPERIMENTAL APPROACH RT-PCR experiments were performed using mouse tracheal epithelial cells for ChAT and organic cation transporter (OCT) transcripts. Components of tracheal airway lining fluid were analysed with desorption electrospray ionization (DESI) MS. Effects of nicotine on mouse tracheal epithelial ion transport were examined with Ussing-chamber experiments. KEY RESULTS Transcripts encoding ChAT and OCT1–3 were detected in mouse tracheal epithelial cells. The DESI experiments identified ACh in the airway lining fluid. Luminal ACh induced an immediate, dose-dependent increase in the transepithelial ion current (EC50: 23.3 µM), characterized by a transient peak and sustained plateau current. This response was not affected by the Na+-channel inhibitor amiloride. The Cl--channel inhibitor niflumic acid or the K+-channel blocker Ba2+ attenuated the ACh effect. The calcium ionophore A23187 mimicked the ACh effect. Luminal nicotine or muscarine increased the ion current. Experiments with receptor gene-deficient animals revealed the participation of muscarinic receptor subtypes M1 and M3. CONCLUSIONS AND IMPLICATIONS The presence of luminal ACh and activation of transepithelial ion currents by luminal ACh receptors identifies a novel non-neuronal cholinergic pathway in the airway lining fluid. This pathway could represent a novel drug target in the airways.

Negative ion desorption electrospray ionization (DESI) was used for the analysis of an ex vivo tissue sample set comprising primary colorectal adenocarcinoma samples and colorectal adenocarcinoma liver metastasis samples. Frozen sections (12 μm thick) were analyzed by means of DESI imaging mass spectrometry (IMS) with spatial resolution of 100 μm using a computer-controlled DESI imaging stage mounted on a high resolution Orbitrap mass spectrometer. DESI-IMS data were found to predominantly feature complex lipids, including phosphatidyl-inositols, phophatidyl-ethanolamines, phosphatidyl-serines, phosphatidyl-ethanolamine plasmalogens, phosphatidic acids, phosphatidyl-glycerols, ceramides, sphingolipids, and sulfatides among others. Molecular constituents were identified based on their exact mass and MS/MS fragmentation spectra. An identified set of molecules was found to be in good agreement with previously reported DESI imaging data. Different histological tissue types were found to yield characteristic mass spectrometric data in each individual section. Histological features were identified by comparison to hematoxylin-eosin stained neighboring sections. Ions specific to certain histological tissue types (connective tissue, smooth muscle, healthy mucosa, healthy liver parenchyma, and adenocarcinoma) were identified by semi-automated screening of data. While each section featured a number of tissue-specific species, no potential global biomarker was found in the full sample set for any of the tissue types. As an alternative approach, data were analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA) which resulted in efficient separation of data points based on their histological types. A pixel-by-pixel tissue identification method was developed, featuring the PCA/LDA analysis of authentic data set, and localization of unknowns in the resulting 60D, histologically assigned LDA space. Novel approach was found to yield results which are in 95% agreement with the results of classical histology. KRAS mutation status was determined for each sample by standard molecular biology methods and a similar PCA/LDA approach was developed to assess the feasibility of the determination of this important parameter using solely DESI imaging data. Results showed that the mutant and wild-type samples fully separated. DESI-MS and molecular biology results were in agreement in 90% of the cases.

The triglyceride composition and oxidation behavior of edible oil and margarine samples were analyzed by desorption electrospray ionization mass spectrometry (DESI-MS). For the characterization of the lipids, the chain length and the degree of unsaturation of the fatty acids were determined. The measurements were carried out in positive ion mode; the triglycerides were detected as alkali metal or ammonium adducts. The DESI solvent was water/methanol 1:1 (v/v); measurements were carried out both with and without the addition, as an ionizing agent, of ammonium acetate that enhances the signal intensity of the ammonium adduct ions. The spectra were interpreted for both cases and intensities were compared. Triglyceride monomers and dimers were observed in the spectra. Tandem mass spectrometric (MS/MS) measurements were carried out to determine the structure of the triglycerides. It was demonstrated that the terminal fatty acids in the sn1- or sn3-position are more likely to be cleaved than the internal fatty acid (sn2-position). Characteristic triglyceride patterns were obtained using a simple and rapid sample preparation protocol comprising the simple deposition of samples onto a glass carrier surface. The triglyceride data was analyzed by principal component analysis (PCA). The different edible oils were clearly separated and the hydrogenated derivatives were identified by their triglyceride spectra. The oxidation of the oil samples was observed and the oxidation products were detected and identified. This method provides a fast and simple technique for the detection and analysis of triglycerides in oil- or fat-containing samples ranging from food items to tissue samples. The potential application areas include nutritional studies, the food industry and cosmetics.