Analysis of free and esterified sterols in fats and oils by flash chromatography, gas chromatography and electrospray tandem mass spectrometry

Characterizing Edible Oils by Oblique-Incidence Reflectivity Difference Combined with Machine Learning Algorithms

Due to the significant price differences among different types of edible oils, expensive oils like olive oil are often blended with cheaper edible oils. This practice of adulteration in edible oils, aimed at increasing profits for producers, poses a major concern for consumers. Furthermore, adulteration in edible oils can lead to various health issues impacting consumer well-being. In order to meet the requirements of fast, non-destructive, universal, accurate, and reliable quality testing for edible oil, the oblique-incidence reflectivity difference (OIRD) method combined with machine learning algorithms was introduced to detect a variety of edible oils. The prediction accuracy of Gradient Boosting, K-Nearest Neighbor, and Random Forest models all exceeded 95%. Moreover, the contribution rates of the OIRD signal, DC signal, and fundamental frequency signal to the classification results were 45.7%, 34.1%, and 20.2%, respectively. In a quality evaluation experiment on olive oil, the feature importance scores of three signals reached 63.4%, 18.9%, and 17.6%. The results suggested that the feature importance score of the OIRD signal was significantly higher than that of the DC and fundamental frequency signals. The experimental results indicate that the OIRD method can serve as a powerful tool for detecting edible oils.

In-House Validation of an SPE-GC-FID Method for the Detection of Free and Esterified Hydroxylated Minor Compounds in Virgin Olive Oils

Minor compounds in vegetable oils are distributed between free and esterified forms, and the ratio of these two fractions could represent an important parameter for assessment of oil authenticity. A simple method based on offline SPE-GC-FID for the analysis of free and esterified hydroxylated minor compounds in olive and sunflower oils has been developed and in-house validated. A satisfactory repeatability relative standard deviation (<7.5%) was obtained in all cases. The method, which requires simple instrumentation, allows for reliable quantification in a single chromatographic run with the advantages of minimizing sample manipulation, use of toxic solvents and reagents, and time consumption. The analytical procedure was applied to pure oil samples, including 15 authentic extra virgin olive oils collected from different European countries (Spain, Italy, Greece, and Portugal). Finally, the proposed SPE-GC-FID methodology could detect changes in the ratio between the free and esterified forms in pure extra virgin olive oil when mixed with refined sunflower oil at different percentages of 2, 5, 10, 15, and 20% (w/w) to simulate adulteration.

Simultaneous determination of tocopherols, carotenoids and phytosterols in edible vegetable oil by ultrasound-assisted saponification, LLE and LC-MS/MS

A method was developed to simultaneously determine eight bioactive compounds in edible oil based on ultrasound-assisted saponification, liquid-liquid extraction and liquid chromatography coupled with tandem mass spectrometry. Central composite design was employed to optimize ultrasonic temperature and time of saponification. Sample treatment was conducted by ultrasound-assisted saponification at temperature of 75 °C for 40 min. Limits of detection and limits of quantification ranged from 2.0 to 3.2 and from 6.1 to 10.0 ng/mL, respectively. Linear correlations were obtained (R² > 0.99) and the recoveries at three spiked levels were between 81.7% and 112.0%. This method was employed to determine eight compounds in camellia oils and olive oils. As results, the contents of stigmasterol, δ-tocopherol, γ-tocopherol, β-carotene and lutein in camellia oils were significantly higher than those in olive oils (p < 0.05). The proposed method can be successfully used to determination of these eight active compounds in camellia oil and other edible oils.

Quantification of Cholesterol and Cholesteryl Ester by Direct Flow Injection High-Resolution Fourier Transform Mass Spectrometry Utilizing Species-Specific Response Factors

The quantification of free cholesterol (FC) and cholesteryl ester (CE) in mammalian samples is of great interest for basic science and clinical lipidomics. Here, we evaluated the feasibility of direct flow injection analysis (FIA) coupled to electrospray ionization high-resolution mass spectrometry (ESI-HRMS) to quantify FC and CE in lipid extracts from human serum, cultured cells, and mouse liver. Despite poor ionization efficiency of FC, the limit of quantitation was sufficient for precise and accurate quantification of FC by multiplexed HRMS (MSX) analysis without using a derivatization step. However, it was demonstrated that, upon full scan Fourier transform MS (FTMS) quantification, CE species show substantial differences in their analytical responses depending on number of double bonds, length of the acyl chain, infused lipid concentration, and other lipid components. A major determinant for these response differences is their susceptibility to in-source fragmentation. In particular, introduction of double bonds lowers the degree of in-source fragmentation. Therefore, CE species-specific response factors need to be applied for CE quantification by FTMS to achieve accurate concentrations. Method validation demonstrated that FIA-ESI-HRMS (MSX and FTMS) is applicable for quantification of FC and CE in samples used in basic science as well as clinical studies such as cultured cells, tissue homogenates, and serum.

Absolute quantification of cholesteryl esters using liquid chromatography-tandem mass spectrometry uncovers novel diagnostic potential of urinary sediment

BACKGROUND

Urine has been utilized as a source of biomarkers in renal disease. However, urinary lipids have not attracted much attention so far. Here we studied urinary cholesteryl ester (CE) and its relevance in renal disease.

METHODS

Quantitative analysis of CE molecular species in serum, urinary supernatant, and urinary sediment from patients with renal disease (N=64) and non-renal disease (N=23) was carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and deuterated CEs as internal standards.

RESULTS

Validation study showed good precision and accuracy of LC-MS/MS. Many CE species were detected in the urinary sediment and supernatant in the renal disease group, whereas only a few CE species were detected in the other group. In the renal disease group, the sum of the concentrations of all CE species showed a significant correlation between the sediment and the supernatant from urinary samples (r=0.876, p<0.001); however, the composition of CEs was significantly different between them. Further, the composition of CEs of the supernatant was similar to that of the serum.

CONCLUSIONS

Our LC-MS/MS analysis uncovered a distinct CE profile in urinary sediment from patients with renal disease, suggesting a possible contribution of CEs in urothelial cells to the development of renal disease.

Liquid chromatography-quadrupole time of flight tandem mass spectrometry-based targeted metabolomic study for varietal discrimination of grapes according to plant sterols content

Grapevine and derived products are rich in a wide range of compounds and its quality mainly depends on its metabolites, as a result of viticulture practices. Plant sterols, also called phytosterols (PS), are secondary metabolites regarded as bioactive substance present in grape berries and other plant-based food. The present study deals with a metabolomic approach focusing on phytosterols family in six varieties of Rioja grapes (Cabernet Sauvignon, Tempranillo, Graciano, Garnacha, White Garnacha and Viura), in order to find significant differences among them. Liquid chromatography- mass spectrometry with a quadrupole-time of flight mass analyzer (LC-QTOF) was used to find as many metabolites as possible in the different grape berry fractions, and using statistics to help finding significant clustering of the metabolic profile of pulp, peel and seeds in relation to the variety. The best chromatographic and detection conditions were achieved by gas phase ionization via atmospheric pressure chemical ionization (APCI) in positive mode. Furthermore, analysis with electrospray (ESI) is also needed for phytosterol derivatives confirmation. Putative compounds of interest in the analyzed samples were found by an automated compound extraction algorithm (Molecular Feature Extraction, MFE) and an initial differential expression from the data was created with the aid of commercial software. Once the data were collected, the results were filtered, aligned and normalized, and evaluating applying one-way analysis of variance (ANOVA) with a 95% significance level. For sample class prediction, partial least square-discriminant analysis (PLS-DA) is used as a supervised pattern recognition method and excellent separation among the grape varieties is shown. An overall accuracy of 93.3% (pulp samples), 100.0% (peel) or 96.7% (seeds) in discriminating between grape varieties was achieved when comparing the different fractions. In general, 7 PS derivatives were identified with ID scores higher than 84%.

PBRM1 Regulates the Expression of Genes Involved in Metabolism and Cell Adhesion in Renal Clear Cell Carcinoma

Polybromo-1 (PBRM1) is a component of the PBAF (Polybromo-associated-BRG1- or BRM-associated factors) chromatin remodeling complex and is the second most frequently mutated gene in clear-cell renal cell Carcinoma (ccRCC). Mutation of PBRM1 is believed to be an early event in carcinogenesis, however its function as a tumor suppressor is not understood. In this study, we have employed Next Generation Sequencing to profile the differentially expressed genes upon PBRM1 re-expression in a cellular model of ccRCC. PBRM1 re-expression led to upregulation of genes involved in cellular adhesion, carbohydrate metabolism, apoptotic process and response to hypoxia, and a downregulation of genes involved in different stages of cell division. The decrease in cellular proliferation upon PBRM1 re-expression was confirmed, validating the functional role of PBRM1 as a tumor suppressor in a cell-based model. In addition, we identified a role for PBRM1 in regulating metabolic pathways known to be important for driving ccRCC, including the regulation of hypoxia response genes, PI3K signaling, glucose uptake, and cholesterol homeostasis. Of particular novelty is the identification of cell adhesion as a major downstream process uniquely regulated by PBRM1 expression. Cytoskeletal reorganization was induced upon PBRM1 reexpression as evidenced from the increase in the number of cells displaying cortical actin, a hallmark of epithelial cells. Genes involved in cell adhesion featured prominently in our transcriptional dataset and overlapped with genes uniquely regulated by PBRM1 in clinical specimens of ccRCC. Genes involved in cell adhesion serve as tumor suppressor and maybe involved in inhibiting cell migration. Here we report for the first time genes linked to cell adhesion serve as downstream targets of PBRM1, and hope to lay the foundation of future studies focusing on the role of chromatin remodelers in bringing about these alterations during malignancies.

Analysis of sitosteryl oleate esters in phytosterols esters enriched foods by HPLC-ESI-MS(2.)

Phytosteryl esters (PE)-enriched spreads are marketed for eating and cooking purposes. Temperature and also light exposure are the major factors leading to the formation of PE oxides in food matrix. In this study a high-speed HPLC-MS(2) method was developed to analyze the major PE present in PE-enriched spreads: sitosteryl oleate (SO) and its oxidation products, by using synthesized compounds as standards. This analytical method was used to quantify seven SO oxides formed in PE-enriched spreads after heating at different temperatures for varying time periods and after prolonged exposure to sunlight. Quantification of remaining native SO was also performed after these different treatments. It was found that under specific heating conditions the decrease of the SO amount was much more important compared to the formation of SO oxides showing that many other products are formed. In contrast to heating, sunlight radiation did not result in the degradation of SO and very few oxides were formed.

A method for simultaneous analysis of phytosterols and phytosterol esters in tobacco leaves using non aqueous reversed phase chromatography and atmospheric pressure chemical ionization mass spectrometry detector

While numerous analytical methods for phytosterols have been reported, the similar polarity and large molecules of phytosterol esters have made the methods lengthy and complicated. For this reason, an analytical method that could completely separate phytosterol esters including the higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid in addition to phytosterols without preliminary separation was developed. The separation was accomplished by non-aqueous reversed phase chromatography technique using only acetone and acetonitrile. An atmospheric pressure chemical ionization/mass spectrometry detector configured at selected ion monitoring mode was hyphenated with the separation system to detect phytosterols and phytosterol esters. Twenty-four types of these were consequently separated and then identified with their authentic components. The calibration curve was drawn in the range of about 5 to 25,000 ng/mL with a regression coefficient over 0.999. The limit of detection and limit of quantification, respectively, ranged from 0.9 to 3.0 ng/mL and from 3.0 to 11.0 ng/mL. Recovery rates ranged from 80 to 120%. The quantification results were subjected to statistical analysis and hierarchical clustering analysis, and were used to determine the differences in the amounts of phytosterols and phytosterol esters across tobacco leaves. The newly developed method succeeded in clarifying the whole composition of phytosterols and phytosterol esters in tobacco leaves and in explaining compositional differences across the variety of tobacco leaves.

Quantitative profiling of major neutral lipid classes in human meibum by direct infusion electrospray ionization mass spectrometry

PURPOSE

The purpose of this investigation was to better understand lipid composition in human meibum.

METHODS

Intact lipids in meibum samples were detected by direct infusion electrospray ionization mass spectrometry (ESI-MS) analysis in positive detection mode using sodium iodide (NaI) as an additive. The peak intensities of all major types of lipid species, that is, wax esters (WEs), cholesteryl esters (CEs), and diesters (DEs) were corrected for peak overlapping and isotopic distribution; an additional ionization efficiency correction was performed for WEs and CEs, which was simplified by the observation that the corresponding ionization efficiency was primarily dependent on the specific lipid class and saturation degree of the lipids while independent of the carbon chain length. A set of WE and CE standards was spiked in meibum samples for ionization efficiency determination and absolute quantitation.

RESULTS

The absolute amount (μmol/mg) for each of 51 WEs and 31 CEs in meibum samples was determined. The summed masses for 51 WEs and 31 CEs accounted for 48 ± 4% and 40 ± 2%, respectively, of the total meibum lipids. The mass percentages of saturated and unsaturated species were determined to be 75 ± 2% and 25 ± 1% for CEs and 14 ± 1% and 86 ± 1% for WEs. The profiles for two types of DEs were also obtained, which include 42 α,ω Type II DEs, and 21 ω Type I-St DEs.

CONCLUSIONS

Major neutral lipid classes in meibum samples were quantitatively profiled by ESI-MS analysis with NaI additive.

Cholesterol efflux analyses using stable isotopes and mass spectrometry

Cholesterol efflux from macrophages and the vascular wall is the initial step of the cardiovascular protective reverse cholesterol transport process. This study demonstrates a mass spectrometry based assay to measure the cellular and medium content of [d(7)]cholesterol and unlabeled cholesterol that can be used to measure cholesterol efflux from cell lines. Using a triple-quadrupole electrospray ionization-MS instrument in direct infusion mode, product ion scanning for m/z 83, neutral loss (NL) 375.5 scanning, and NL 368.5 scanning were used to detect cholesterol (as an acetylated derivative), [d(7)]cholesteryl ester (CE), and unlabeled CE, respectively. The same mass of [d(7)]cholesterol was substituted for [(3)H]cholesterol under standard efflux assay conditions. At the end of [d(7)]cholesterol loading, the intracellular mass of [d(7)]cholesterol was twofold greater than that of unlabeled cholesterol, and the intracellular [d(7)]CE profile was similar to that of unlabeled CE. Efflux of cholesterol to apolipoprotein A-I and high-density lipoproteins was similar comparing efflux of either [d(7)]cholesterol or [(3)H]cholesterol as measured by following efflux of the tracers only. This technique also can be used to assess the efflux of unlabeled cholesterol to acceptors in medium that are initially cholesterol-free (e.g., apolipoprotein A-I). Taken together, this mass spectrometry-based assay provides new molecular detail to assess cholesterol efflux.

Electrospray ionization tandem mass spectrometry of sodiated adducts of cholesteryl esters

Cholesteryl esters (CE) are important lipid storage molecules. The present study demonstrates that sodiated adducts of CE molecular species form positive ions that can be detected in both survey scan mode as well as by exploiting class-specific fragmentation in MS/MS scan modes. A common neutral loss for CE is the loss of cholestane (NL 368.5), which can be used to specifically quantify tissue CE molecular species. Using this MS/MS technique, CE molecular species were quantified in mouse monocyte-derived macrophages (J774 cells) incubated with either linoleic (18:2) or arachidonic acid (20:4). These studies revealed that arachidonic acid was not only incorporated into the CE pool, but also was elongated resulting in the accumulation of 22:4 and 24:4 CE molecular species in macrophages. Additionally, this technique was used to quantify CE molecular species present in crude lipid extracts from plasma of female mice fed a Western diet, which led to an enrichment in CE molecular species containing monounsaturated fatty acids compared to female mice fed a normal chow diet. Last, NL 368.5 spectra revealed the oxidation of the aliphatic fatty acid residues of CE molecular species containing polyunsaturated fatty acids. Taken together, these studies demonstrate the utility of using sodiated adducts of CE in conjunction with direct infusion electrospray ionization tandem mass spectrometry to rapidly quantify CE molecular species in biological samples.

Analysis of cholesteryl esters and diacylglycerols using lithiated adducts and electrospray ionization-tandem mass spectrometry

Cholesteryl ester (CE) and diacylglycerol (DAG) molecular species are important lipid storage and signaling molecules. Mass spectrometric analyses of these lipids are complicated by the presence of isobaric molecular ions shared by these lipid classes and by relatively poor electrospray ionization, which is a consequence of an inherently weak dipole moment in these lipid classes. The current study demonstrates that lithiated adducts of CE and DAG molecular ions have enhanced ionization and lipid class-specific fragmentation in tandem mass spectrometry (MS/MS) scan modes, thereby allowing the implementation of strategies capable of lipid class-specific detection. Using neutral loss (NL) mode for the loss of cholestane from cholesterol esters (NL 368.5) and specific selected reaction monitoring for DAG molecular species, the response of specific molecular species to that of internal standards was determined. CE and DAG molecular species were quantified in human coronary artery endothelial cells (HCAECs) incubated with both palmitic acid and oleic acid. Furthermore, NL 368.5 spectra revealed the oxidation of the aliphatic fatty acid residues of CE molecular species. Taken together, these studies demonstrate a new analytical approach to assessing CE and DAG molecular species that exploits the utility of lithiated adducts in conjunction with MS/MS approaches.

Separation and identification of neutral cereal lipids by normal phase high-performance liquid chromatography, using evaporative light-scattering and electrospray mass spectrometry for detection

A novel method was developed for the analysis of molecular species in neutral lipid classes, using separation by normal phase high-performance liquid chromatography, followed by detection by evaporative light-scattering and electrospray ionization tandem mass spectrometry. Monoacid standards, i.e. sterol esters, triacylglycerols, fatty acids, diacylglycerols, free sterols and monoacylglycerols, were separated to baseline on microbore 3 microm-silica gel columns. Complete or partial separation of molecular species in each lipid class permitted identification by automatic tandem mass spectrometry of ammonium adducts, produced via positive electrospray ionization. After optimization of the method, separation and identification of molecular species of various lipid classes was comprehensively tested by analysis of neutral lipids from the free lipid extract of maize flour.

Distribution of free and esterified ergosterols in the medicinal fungus Ganoderma lucidum

The fruiting bodies, spores, and lipid from the spores of Ganoderma lucidum have been widely used for medicinal purpose in China. Ergosterol content may be a suitable marker for evaluating the quality of ganoderma spore and ganoderma spore lipid (GSL) products. A gradient reversed-phase high-performance liquid chromatography method was developed for the simultaneous determination of free and esterified ergosterols in G. lucidum. The contents of free and esterified ergosterols in the different parts (the stipe, pileus, tubes, and spores) of G. lucidum and GSL were determined. The results showed that total ergosterol levels in the stipe, pileus, tubes, and spores of G. lucidum were between 0.8 and 1.6 mg/g. The relative abundances of free to esterified ergosterol were different in the different parts of G. lucidum. The spores and the tubes, the hymenophore tissue that contains the spore-producing cells, have a considerably higher percentage of ergosteryl esters (41.9 and 39.7% of total ergosterol) in comparison with the pileus and stipe tissues (3.6 and 6.2%).

Automated identification and quantification of glycerophospholipid molecular species by multiple precursor ion scanning

We report a method for the identification and quantification of glycerophospholipid molecular species that is based on the simultaneous automated acquisition and processing of 41 precursor ion spectra, specific for acyl anions of common fatty acids moieties and several lipid class-specific fragment ions. Absolute quantification of identified species was linear within a concentration range of 10 nM-100 microM and was achieved by spiking into total lipid extracts a set of synthetic lipid standards with diheptadecanoyl (17:0/17:0) fatty acid moieties, representing six common classes of glycerophospholipids. The automated analysis of total lipid extracts was powered by a robotic nanoflow ion source and produced currently the most detailed description of the glycerophospholipidome.

Quantification of free and esterified sterols in Portuguese olive oils by solid-phase extraction and gas chromatography–mass spectrometry

A simple and accurate method based on solid-phase extraction (SPE), transesterification and gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative analysis of free and esterified sterols of olive oil. In order to achieve better separation of esterified and free sterols, silica and alumina SPE adsorbents were tested. Separations by silica provided more reproducible results. The transesterification of both sterol fractions was found to be more user friendly than saponification as a method to liberate the sterols from the respective esters. The free sterols were then silylated with N,O-bis-trimethylsilyltrifluoroacetamide (BSTFA) with 1% of trimethylchlorosilane (TMCS). The most favourable conditions for exploitation of this reagent were established. The optimized methodology was suitable for evaluation of free and esterified sterols in Protected Designation of Origin (PDO) olive oils and monovarietal olive oils with different maturation indices. The prevailing phytosterols in all olive oils were beta-sitosterol and campesterol. The free sterols predominated, although they seemed to decrease with the maturation of the olive fruits.

Determination of ergosterol in ganoderma spore lipid from the germinating spores of Ganoderma lucidum by high-performance liquid chromatography

A gradient reversed-phase high-performance liquid chromatography (HPLC) method was developed for the separation and determination of free ergosterol in ganoderma spore lipid (GSL) extracted from the sporoderm-broken germinating spores of Ganoderma lucidum. Sodium hydroxide in methanol was added for the hydrolysis of ergosteryl esters to determine the total content of ergosterol in GSL by HPLC. A 0.04 M concentration of sodium hydroxide in reaction mixtures was appropriate for the complete hydrolysis of ergosteryl esters without a significant loss of ergosterol during saponification. In addition, the ergosterol content in four commercial GSL softgel supplements from four different firms was determined. The results showed that the ergosterol content in these samples had significant differences. Ergosterol content may be a suitable marker for evaluating the quality of GSL products.

Analysis of phytosterols in foods

Phytosterols are bioactive compounds, one of their most studied and outstanding properties being their cholesterol-lowering activity. This explains the growing interest in the phytosterol contents of foods as either intrinsic or added components. The different steps (extraction, saponification, clean up, chromatographic determination) of plant sterol determination are reviewed, and emphasis is placed on the methods used to assay different phytosterols in food.

High throughput quantification of cholesterol and cholesteryl ester by electrospray ionization tandem mass spectrometry (ESI-MS/MS)

Analysis of free cholesterol (FC) is not well suited for electrospray ionization (ESI); however, cholesteryl ester (CE) form ammonium adducts in positive ion mode and generate a fragment ion of m/z 369 upon collision-induced fragmentation. In order to allow parallel analysis of FC and CE using ESI tandem mass spectrometry (ESI-MS/MS), we developed an acetyl chloride derivatization method to convert FC to cholesteryl acetate (CE 2:0). Derivatization conditions were chosen to provide a quantitative conversion of FC to CE 2:0 without transesterification of naturally occurring CE species. FC and CE were analyzed by direct flow injection analysis using a fragment of m/z 369 in a combination of selected reaction monitoring (SRM) and precursor ion scan for FC and CE, respectively. Quantification was achieved using deuterated D(7)-FC and CE 17:0/CE 22:0 as internal standards as well as calibration lines generated by addition of FC and naturally occurring CE species to the respective sample matrix. The developed assay showed a precision and detection limit sufficient for routine analysis. A run time of 1.3 min and automated data analysis allow high throughput analysis. Loading of human skin fibroblast and monocyte derived macrophages with stable isotope labeled FC showed a potential application of this method in metabolism studies. Together with existing mass spectrometry methodologies for lipid analysis, the present methodology will provide a useful tool for clinical and biochemical studies and expands the lipid spectrum that can be analyzed from one lipid sample on a single instrumental platform.

Analysis of fatty acid steryl esters in tetraploid and hexaploid wheats: identification and comparison between chromatographic methods

Fatty acid steryl esters (FASE) in whole meal of 14 genotypes of tetraploid wheats (Triticum dicocconand T. durum) and 17 genotypes of hexaploid wheats (T. spelta and T. aestivum) were analyzed using different chromatographic strategies. By both GC-FID and HPLC-ELSD, tetraploid wheats are lacking two major peaks. The amounts of FASE, calculated on the basis of the GC-FID analysis, were double in hexaploid species as compared to tetraploids (40 and 20 mg/100 g db, respectively). HPLC with ESI-MS detection enabled the identification of FASE by the characteristic fragmentations and ion-adducts of each molecule. The distribution of steryl residues was not different between the wheat species: the main class of steryl derivatives found was the beta-sitosteryl derivatives, followed by campesteryl derivatives with small amounts of stigmasteryl esters. The esterified fatty acids explain the difference between the hexaploid and tetraploid wheats. In particular, small amounts of campesteryl and beta-sitosteryl, while no trace of stigmasteryl palmitates, were found in T. durum or its hulled ancestor T. dicoccon. Steryl oleates were not detectable in T. aestivum or its hulled ancestor T. spelta, which is consistent with the filogenesis of tetraploid and hexaploid species. Both chromatographic techniques (GC and HPLC) showed that FASE are useful to discriminate between hexaploid and tetraploid wheats from both qualitative and quantitative points of view.

Characterization of vegetable oils: detailed compositional fingerprints derived from electrospray ionization fourier transform ion cyclotron resonance mass spectrometry

Adulteration of vegetable oil is of concern for both commercial and health reasons. Compositional based fingerprints can potentially reveal both the oil source and its possible adulteration. Here, electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) resolves and identifies literally thousands of distinct chemical components of commercial canola, olive, and soybean oils, without extraction or other wet chemical separation pretreatment. In negative-ion ESI FT-ICR MS, the acidic components of soybean oil are easily distinguished from those of canola and olive oil based on relative abundances of C(18) fatty acids, whereas olive oil differs from canola and soybean oil based on relative abundances of tocopherols. In positive-ion ESI FT-ICR MS, the three oils are readily distinguished according to the relative abundances of di- and triacylglycerols with various numbers of double bonds in the fatty acid chains. We demonstrate the detection of soybean oil as an adulterant of olive oil, based on relative abundances of members of each of several chemical families. We suggest that the detailed chemical compositions of vegetable oils can be used to characterize them and to detect and identify adulterants.

Analysis of plant sterol and stanol esters in cholesterol-lowering spreads and beverages using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectroscopy

Plant sterol and stanol esters were separated on a Luna hexyl-phenyl column using a gradient of acetonitrile (90-100%) in water. The eluted compounds were detected by atmospheric pressure chemical ionization (APCI)-mass spectroscopy (MS) in the positive mode. Sterol and stanol esters produced [M + H - HOOCR](+) ions. Application of the hyphenated technique-LC-MS-allowed differentiation between a number of esters of sitosterol, campesterol, stigmasterol, and (tentatively) avenasterol, as well as sitostanol and campestanol esters. With cholesteryl decanoate used as the internal standard, the method showed good linearity, precision, and reproducibility. The method required minimal sample pretreatment and can be applied to samples with high water content (juices) as well as samples with high oil content (margarine spreads). The method could be useful for the analysis of sterol and stanol esters in fortified food products.

Recent advances in the application of mass spectrometry in food-related analysis

A review is presented on recent applications of mass spectrometry (MS)-based techniques for the analysis of compounds of food concern. Substances discussed are naturally occurring compounds in food products such as lipids, oligosaccharides, proteins, vitamins, flavonoids and related substances, phenolic compounds and aroma compounds. Among xenobiotics, applications of MS techniques for the analysis of pesticides, drug residues, toxins, amines and migrants from packaging are overviewed. Advances in the analysis of trace metals of nutritional and toxicological interest by MS with inductively coupled plasma (ICP) source are presented. The main features of mass spectrometry combined with separation instruments are discussed in food-related analysis. Examples of mass spectrometry and tandem MS (MS-MS) are provided. The development and application of matrix-assisted laser desorption ionization (MALDI) and electrospray (ESI) to the analysis of peptides and proteins in food is discussed. This survey will attempt to cover the state-of-the-art up from 1999 to 2001.