Ionization Linear Ion Trap Research Articles

Infrared Photodissociation Spectroscopy of Water-Tagged Ions with a Widely Tunable Quantum Cascade Laser for Planetary Science Applications.

This work presents a benchtop method for collecting the room temperature gas phase infrared (IR) action spectra of protonated amino acids and their isomers. The adopted setup uses a minimally modified commercial electrospray ionization linear ion trap mass spectrometer (ESI-LIT-MS) coupled to a broadband continuous wave (cw) quantum cascade laser (QCL) source. This approach leverages messenger assisted action spectroscopic techniques using water-tagged molecular ions with complex formation, irradiation, and subsequent analysis, all taking place within a single linear ion trap stage. This configuration thus circumvents the use of multiple mass selection and analysis stages, cryogenic buffer cells, and complex high-power laser systems typically called upon to execute these techniques. The benchtop action spectrometer is used to collect the 935-1600 cm-1 (6.2-10.7 μm) IR action spectrum of a collection of amino acids and a dipeptide with results cross referenced against literature examples obtained with a free electron laser source. Recorded IR spectra are used for the analysis of binary mixture samples composed of constitutional isomers α-alanine and β-alanine with ratios determined to ∼4% measurement uncertainty without the aid of a front-end separation stage. This turn-key QCL-based approach is a major step in showing the viability of tag-based action spectroscopic techniques for use in future in situ planetary science sensors and general analytical applications.

Rapid analysis of pharmaceutical and personal care products by soft microwave-based plasma ionization-linear ion trap mass spectrometer (SMPI-LTQ) in natural water.

In this study, a soft microwave plasma torch (SMPT) combined with a mass spectrometer (MS) was used for the first time as an analytical method to detect and analyze various pharmaceutical and personal care products (PPCPs) in aquatic environments without the need for sample pretreatment. For this purpose, ambient SMPT was used to generate plasma for ionizing the analyte molecules. Accordingly, nine PPCPs were identified by the SMPT-MS, and their identification was verified by collision-induced dissociation (CID). The technique's performance was verified with known PPCP samples, and the limits of detection (LOD) and quantification (LOQ) obtained over a linear range of 50-1 μg/L were 1.56 to 2.81 and 2.07 to 3.62 μg/L, respectively, with the standard addition recovery rate falling between 87.14 and 115.16%. These results show that the method has excellent sensitivity and selectivity, suggesting that SMPT can rapidly and directly detect PPCPs in environmental water, making it a promising method for rapid water quality inspection.

Comparison of APCI orbitrap MS and GCxGC/EI TOF MS for the hydrocarbon analysis of heavy base oils

The performance of positive-ion mode atmospheric pressure chemical ionization linear quadrupole ion trap orbitrap mass spectrometry (APCI LQIT Orbitrap MS) has been compared to that of two-dimensional gas chromatography coupled with positive-ion mode electron ionization time-of-flight mass spectrometry (GCxGC/EI TOF MS) for the analysis of group III heavy base oils. Upon APCI, all compounds were predominantly ionized via protonation. However, protonated alkanes are not stable and predominantly generated [M−H]+ ions via elimination of a hydrogen molecule from the protonated molecule. The high-resolution APCI mass spectra provided elemental composition information for the compounds while low-resolution APCI mass spectra were used for semiquantitative evaluation of the relative amounts of the compounds. Ions corresponding to compounds in seven hydrocarbon classes, i.e., (1) linear and branched alkanes, (2) monocycloalkanes, (3) dicycloalkanes, (4) tricycloalkanes and alkylbenzenes, (5) tetracycloalkanes, (6) pentacycloalkanes, and (7) hexacycloalkanes were identified. On the other hand, the GCxGC/EI TOF MS method enabled the chromatographic separation of most analytes. The measured EI mass spectra were used for the identification of the compounds while the GC peak areas were used for semiquantitative evaluation. The detected compounds were classified into three different hydrocarbon classes, (1) linear and branched alkanes, (2) cycloalkanes, and (3) aromatic hydrocarbons. The (+)APCI LQIT Orbitrap MS method was found to be faster and to provide more information for the larger compounds in the samples. For example, polycycloalkanes were only detected by using (+)APCI MS. However, no aromatic compounds were detected. Data processing was more straightforward than when using the GCxGC/EI TOF MS method. However, the latter method provided more accurate results for aromatic hydrocarbons and small alkanes as the analysis of small alkanes by using (+)APCI MS is limited due to the fact that [M−H]+ ions of small alkanes overlap with alkane fragment ions. Both light and heavy aliphatic and aromatic hydrocarbons were detected by using the GCxGC/EI TOF MS method but not polycycloalkanes. Therefore, these two methods complement each other, and each has different strengths and weaknesses.

Identification and Quantification of Urinary Microbial Phenolic Metabolites by HPLC-ESI-LTQ-Orbitrap-HRMS and Their Relationship with Dietary Polyphenols in Adolescents.

This study aimed to develop and validate a liquid chromatography/electrospray ionization-linear ion trap quadrupole-Orbitrap-high-resolution mass spectrometry (HPLC/ESI-LTQ-Orbitrap-HRMS) method to identify and quantify urinary microbial phenolic metabolites (MPM), as well as to explore the relationship between MPM and dietary (poly)phenols in Spanish adolescents. A total of 601 spot urine samples of adolescents aged 12.02 ± 0.41 years were analyzed. The quantitative method was validated for linearity, limit of detection, limit of quantification, recovery, intra- and inter-day accuracy and precision, as well as postpreparative stability according to the criteria established by the Association of Official Agricultural Chemists International. A total of 17 aglycones and 37 phase II MPM were identified and quantified in 601 spot urine samples. Phenolic acids were the most abundant urinary MPM, whereas stilbenes, hydroxytyrosol, and enterodiol were the least abundant. Urinary hydroxycoumarin acids (urolithins) were positively correlated with flavonoid and total (poly)phenol intake. An HPLC-ESI-LTQ-Orbitrap-HRMS method was developed and fully validated to quantify MPM. The new method was performed accurately and is suitable for MPM quantification in large epidemiological studies. Urinary lignans and urolithins are proposed as potential biomarkers of grain and nut intake in an adolescent population.

Synthesis and analytical differentiation of a novel synthetic cathinone 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidin-1-yl)butan-1-one (5-PPDI) and its regioisomers

The differentiation of a controlled drug from uncontrolled novel compounds related to regioisomers is a significant issue in forensics. The compound 1-(2,3-dihydro-1H-inden-5-yl)-2-(pyrrolidin-1-yl)butan-1-one (5-PPDI) is a novel synthetic cathinone first identified in 2015 as a new psychoactive substance. 5-PPDI is the indanyl analog of α-PBP, a typical synthetic cathinone, as well as the aliphatic ring analog of MDPBP, a synthetic cathinone with a heterocyclic ring. 5-PPDI can have three possible regioisomers, 1-(2,3-dihydro-1H-inden-1-yl)-2-(pyrrolidin-1-yl)butan-1-one (1-PPDI), 1-(2,3-dihydro-1H-inden-2-yl)-2-(pyrrolidin-1-yl)butan-1-one (2-PPDI), and 1-(2,3-dihydro-1H-inden-4-yl)-2-(pyrrolidin-1-yl)butan-1-one (4-PPDI), differing by the substituted position of the alkyl side-chain. In this study, 5-PPDI and its three regioisomers were synthesized from commercially available precursor compounds and analyzed by gas chromatography/electron ionization–quadrupole mass spectrometry (GC/EI–Q-MS) and by liquid chromatography/electrospray ionization–linear ion trap mass spectrometry (LC/ESI–LIT–MS). The four PPDI isomers could be differentiated by GC/EI–Q-MS with three types of separation columns and by 2nd generation product ion spectra (MS3) analysis using ESI–LIT–MS.

Comprehensive Identification of Glycosphingolipids in Human Plasma Using Hydrophilic Interaction Liquid Chromatography-Electrospray Ionization Mass Spectrometry.

Glycosphingolipids (GSL) represent a highly heterogeneous class of lipids with many cellular functions, implicated in a wide spectrum of human diseases. Their isolation, detection, and comprehensive structural analysis is a challenging task due to the structural diversity of GSL molecules. In this work, GSL subclasses are isolated from human plasma using an optimized monophasic ethanol–water solvent system capable to recover a broad range of GSL species. Obtained deproteinized plasma is subsequently purified and concentrated by C18-based solid-phase extraction (SPE). The hydrophilic interaction liquid chromatography coupled to electrospray ionization linear ion trap tandem mass spectrometry (HILIC-ESI-LIT-MS/MS) is used for GSL analysis in the human plasma extract. Our results provide an in-depth profiling and structural characterization of glycosphingolipid and some phospholipid subclasses identified in the human plasma based on their retention times and the interpretation of tandem mass spectra. The structural composition of particular lipid species is readily characterized based on the detailed interpretation of mass spectrometry (MS) and tandem mass spectrometry (MS/MS) spectra and further confirmed by specific fragmentation behavior following predictable patterns, which yields to the unambiguous identification of 154 GSL species within 7 lipid subclasses and 77 phospholipids representing the highest number of GSL species ever reported in the human plasma. The developed HILIC-ESI-MS/MS method can be used for further clinical and biological research of GSL in the human blood or other biological samples.

High expression of tissue O-linked glycans is associated with a malignant phenotype of cholangiocarcinoma.

ObjectiveThis study aimed to investigate the expression of O-linked glycoprotein glycans in tissue of patients with cholangiocarcinoma compared with adjacent normal tissue.MethodsSixty patients with cholangiocarcinoma were included in the study. Permethylated O-linked glycans from intrahepatic cholangiocarcinoma tissue and adjacent normal tissue were analyzed using nano-spray ionization-linear ion trap mass spectrometry. Histochemistry of peanut agglutinin lectin was used for detection and localization of galactose (Gal) 1, N-acetyl-galactosamine (GalNAc) 1.ResultsO-linked glycans from patients with cholangiocarcinoma were composed of di- to hexa-saccharides with a terminal galactose and sialic acids (N-acetylneuraminic acid [NeuAc]). A total of eight O-linked glycan structures were detected. Gal1GalNAc1 and Gal2 N-acetyl-glucosamine 1 GalNAc1 expression was significantly higher in tissue from patients with cholangiocarcinoma compared with adjacent normal tissue, while NeuAc1Gal1GalNAc1 expression was significantly lower. High Gal1GalNAc1 expression was significantly associated with the late stage of cholangiocarcinoma (stages II–IV), lymphatic invasion, and vascular invasion.ConclusionOur study shows expression of O-linked glycans in progression of cholangiocarcinoma and highlights the association of Gal1GalNAc1 with lymphatic and vascular invasion of cholangiocarcinoma.

Investigation of interactions between cytochrome c and ginsenosides by native mass spectrometry and molecular docking simulations.

Ginsenosides are considered to be the main functional components in ginseng and possess various important pharmacological activities. The study of the interactions between ginsenosides and proteins is indispensable for understanding the pharmacological activities of ginsenosides. In this work, the interactions of ginsenosides with cytochrome c (cyt c) were investigated by native mass spectrometry and molecular docking simulations. The interactions of four ginsenosides (Rb1 , Rb3 , Rf, Rg1 ) and cyt c in NH4 OAc solution were investigated by electrospray ionization linear ion trap mass spectrometry (ESI-LTQ-MS). Molecular docking simulations of cyt c complexes were carried out by AutoDock. The native mass spectrometry results showed that the four ginsenosides were directly bound to cyt c, with stoichiometric ratios of 1:1 and 2:1 in NH4 OAc. The order of relative binding abilities of ginsenosides to cyt c obtained by ESI-MS was Rb1 > Rb3 > Rf > Rg1 , which was consistent with the docking results. Moreover, molecular docking simulations also indicated potential binding sites of cyt c and ginsenosides. Hydrogen-bond interaction played a very important role in cyt c binding with ginsenosides. It has been demonstrated that native MS is a useful tool to investigate the interactions of ginsenosides with cyt c. Molecular docking is a good complement to ESI analysis, and can provide information on potential binding sites of cyt c-ginsenoside complexess. This strategy will be helpful to further understand the interactions of proteins and small molecules.

Ganglioside GM2: a potential biomarker for cholangiocarcinoma.

ObjectiveTo investigate the expression of glycosphingolipids in serum and tissue from patients with cholangiocarcinoma compared with healthy controls.MethodsNanospray ionization-linear ion trap mass spectrometry (NSI-MSn) was used to demonstrate the comparative structural glycomics of glycosphingolipids in serum from patients with cholangiocarcinoma (n=15), compared with healthy controls (n = 15). GM2 expression in cholangiocarcinoma tissues (n = 60) was evaluated by immunohistochemistry.ResultsEleven glycosphingolipids were detected by NSI-MSn: CMH (ceramide monohexose), Lac-Cer (galactose (Gal)β1-4 glucose (Glc)β1-1'-ceramide), Gb3 (Galα1-4Galβ1-4Glcβ1-1'-ceramide), Gb4/Lc4 (N-acetylgalactosamine (GalNAc)β1-3Galα1-4Galβ1-4Glcβ1-1'-ceramide/Galβ1-4 N-acetylglucosamine (GlcNAc)β1-3Galβ1-4Glcβ1-1'-ceramide), GM3 (N-acetylneuraminic acid (NeuAc)2-3Galβ1-4Glcβ1-1'-ceramide), GM2 (GalNAcβ1-4[NeuAc2-3]Galβ1-4Glcβ1-1'-ceramide), GM1 (Galβ1-3GalNAcβ1-4[NeuAc2-3]Galβ1-4Glcβ1-1'-ceramide), hFA (hydroxylated fatty acid)-CMH, hFA-Lac-Cer, hFA-Gb3, and hFA-GM3. Lac-Cer was the most abundant structure among the lactosides and globosides (normal, 24.40% ± 0.11%; tumor, 24.61% ± 2.10%), while GM3 predominated among the gangliosides (normal, 29.14% ± 1.31%; tumor, 30.53% ± 4.04%). The two glycosphingolipids that significantly differed between healthy controls and patients with cholangiocarcinoma were Gb3 and GM2. High expression of GM2 was associated with vascular invasion in tissue from patients with cholangiocarcinoma.ConclusionsAltered expression of glycosphingolipids in tissue and serum from patients with cholangiocarcinoma may contribute to tumor growth and progression. The ganglioside GM2, which significantly increased in the serum of patients with cholangiocarcinoma, represents a promising target as a biomarker for cholangiocarcinoma.

Untargeted Metabolomics Analytical Strategy Based on Liquid Chromatography/Electrospray Ionization Linear Ion Trap Quadrupole/Orbitrap Mass Spectrometry for Discovering New Polyphenol Metabolites in Human Biofluids after Acute Ingestion of Vaccinium myrtillus Berry Supplement.

In this work, liquid chromatography, coupled with an electrospray ionization hybrid linear ion trap quadrupole/Orbitrap mass spectrometry, has been used to accurately identify polyphenol metabolites in human serum and urine after acute ingestion of a V. myrtillus berry supplement. The supplement was obtained by cryo-milling of bilberries, which were freeze-dried within 1week after their harvesting, to maintain the berry native composition. Thirty-six derivatives of benzoic acids, hydroxyhippuric acids, cinnamic acids, phenylpropionic acids, phenylvaleric acids, phenylpentenoic acids and abscisic acid, together with two berry-native anthocyanins, one flavonol metabolite and two catechol derivatives were putatively identified in the investigated biofluids. The annotated compounds included 13 metabolites, among glucuronides and sulphates of phenylvaleric and phenylpentenoic acids, which have been identified for the first time in human biofluids after ingestion of V. myrtillus berries. It should be emphasized that the presence of phenylvaleric and phenylpentenoic acid derivatives is in agreement with their origin from fruit native flavanol monomers and oligomers, which are widely distributed in Vaccinium berries, but usually overlooked in metabolomics studies regarding bilberry. The identification of these compounds confirmed the key-role of untargeted metabolomics approach in the discovery of new metabolites which could be biologically active. Graphical Abstract.

Increased expression of the high-mannose M6N2 and NeuAc3H3N3M3N2F tri-antennary N-glycans in cholangiocarcinoma.

Changes in protein glycosylation have been reported in various types of cancer, including cholangiocarcinoma (CCA). Nanospray ionization-linear ion trap mass spectrometry (NSI-MSn) was used in the present study to determine the comparative structural glycomics of the N-linked glycans in the serum of patients with CCA compared with healthy controls. A total of 5 high-mannose and 4 complex N-linked glycans were detected. Mannose7-N-acetyl-glucosamine2 was the most abundant structure among the high-mannose types (control 12.12±2.54 vs. CCA 9.27±2.66%), whereas NeuAc2H2N2M3N2 predominated the complex types (control 61.17±2.55 vs. CCA 64.68±4.23%). The expression of 3 different N-glycans differed significantly between the CCA cases and controls. These included mannose6-N-acetyl-glucosamine2 (P=0.044), mannose9-N-acetyl-glucosamine2 (Ρ=0.030) and NeuAc3H3N3M3N2F (Ρ=0.002). These three glycan structures may therefore be associated with tumor progression in CCA and may be useful for its diagnosis.

Overexpression of ceramide synthase 1 increases C18-ceramide and leads to lethal autophagy in human glioma.

Ceramide synthase 1 (CERS1) is the most highly expressed CERS in the central nervous system, and ceramide with an 18-carbon–containing fatty acid chain (C18-ceramide) in the brain plays important roles in signaling and sphingolipid development. However, the roles of CERS1 and C18-ceramide in glioma are largely unknown. In the present study, measured by electrospray ionization linear ion trap mass spectrometry, C18-ceramide was significantly lower in glioma tumor tissues compared with controls (P < 0.001), indicating that C18-ceramide might have a role in glioma. These roles were examined by reconstitution of C18-ceramide in U251 and A172 glioma cells via addition of exogenous C18-ceramide or overexpression of CERS1, which has been shown to specifically induce the generation of C18-ceramide. Overexpression of CERS1 or adding exogenous C18-ceramide inhibited cell viability and induced cell death by activating endoplasmic reticulum stress, which induced lethal autophagy and inhibited PI3K/AKT signal pathway in U251 and A172 glioma cells. Moreover, overexpression of CERS1 or adding exogenous C18-ceramide increased the sensitivity of U251 and A172 glioma cells to teniposide (VM-26). Thus, the combined therapy of CERS1/C18-ceramide and VM-26 may be a novel therapeutic strategy for the treatment of human glioma.

Enhancing structural characterisation of glucuronidated O-linked glycans using negative mode ion trap higher energy collision-induced dissociation mass spectrometry.

High protein production and secretion with eukaryotic glycosylation machinery make T. reesei RUT-C30 a suitable expression host for recombinant proteins. The N-glycosylation of secreted proteins of RUT-C30 is known to vary depending on culture nutrients but O-glycosylation has been less extensively studied. O-Glycans and glycopeptides from secreted proteins were separated by porous graphitised carbon and C-18 liquid chromatography, respectively. O-Glycans were analysed in negative ion mode by electrospray ionisation linear ion trap mass spectrometry and glycopeptides in positive ion mode by electrospray ionisation hybrid quadrupole-orbitrap mass spectrometry. Tandem mass spectrometry was used on O-glycans and glycopeptides including ion trap higher energy collision-induced dissociation (tHCD) to detect glycan fragments not detectable with standard ion trap fragmentation. tHCD allowed targeted MS3 experiments to be performed on structures containing hexuronic acid, which was not possible with ion trap CID, validating this novel O-glycan composition. Positive mode C18-LC/ESI-MS/MS was used to identify and characterise glycopeptides found to be modified with this class of O-glycans, identifying cellobiohydrolase I as a carrier of these novel O-glycans. Negative mode ion trap higher energy collision-induced dissociation allowed detection and targeted MS3 experiments to be performed on the hexuronic acid substituent of O-glycan structures, which was not possible with ion trap CID, validating the novel O-glycan composition to include hexuronic acid. Using glycopeptide analysis, this novel O-glycan composition was found to be present on the catalytic domain of cellobiohydrolase I, the most abundant secreted protein by T. reesei. These are the first reported O-glycans to contain acidic sugars in fungi and they could have significant implications for cellobiohydrolase I structure and activity as well as the activity of recombinant proteins expressed in this host system. Copyright © 2017 John Wiley & Sons, Ltd.

Differential Expression of O-glycoprotein Glycans in Cholangiocarcinoma Cell Lines.

Protein glycosylation is the most common posttranslational modification in mammalian cells. Aberrant protein glycosylation has been reported in various diseases, including cancer. We identified and quantified the glycan structures of O-linked glycoprotein from cholangiocarcinoma (CCA) cell lines from different histological types and compared their profiles by nanospray ionization-linear ion trap mass spectrometry (NSI-MSn). Five human CCA cell lines, K100, M055, M139, M213 and M214 were characterized. The results showed that the O-linked glycans of the CCA cell lines comprised tri- to hexa-saccharides with terminal galactose and sialic acids: NeuAc1Gal1GalNAc1, Gal2GlcNAc1GalNAc1, NeuAc2Gal1GalNAc1 NeuAc1Gal2GlcNAc1GalNAc1 and NeuAc2Gal2GlcNAc1GalNAc1 All five CCA cell lines showed a similar glycan pattern, but with differences in their quantities. NeuAc1Gal1GalNAc1 proved to be the most abundant structure in poorly differentiated adenocarcinoma (K100; 57.1%), moderately differentiated adenocarcinoma (M055; 42.6%) and squamous cell carcinoma (M139; 43.0%), while moderately to poorly differentiated adenocarcinoma (M214; 40.1%) and adenosquamous cell carcinoma (M213; 34.7%) appeared dominated by NeuAc2Gal1GalNAc1. These results demonstrate differential expression of the O-linked glycans in the different histological types of CCA. All five CCA cell lines have abundant terminal sialic acid (NeuAc) O-linked glycans, suggesting an important role for sialic acid in cancer cells. Our structural analyses of glycans may provide important information regarding physiology of disease-related glycoproteins in CCA.

Analysis and fragmentation mechanisms of hirsutinolide-type sesquiterpene lactones by ultra-high-performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry.

Hirsutinolide-type sesquiterpene lactones (SLs) are natural biologically active compounds mainly found in the genus Vernonia. Very few studies have been published about the fragmentation mechanisms of SLs generally and none about hirsutinolides, although they have drawn attention through their biological and taxonomical interest. This work aims to propose a mass spectrometry fragmentation pattern for hirsutinolides in order to detect and to identify them in a botanical extract. The fragmentation pathways of six pure hirsutinolides isolated from Pseudelephantopus spiralis were established by positive ion electrospray high-resolution linear ion trap Orbitrap tandem mass spectrometry (ESI(+)-HRMS(n) ). A resolutive, hyphenated ultra-high-performance liquid chromatography (UHPLC) coupled to diode array detection (DAD) and ESI(+)-HRMS(n) method was then implemented to separate and analyze them. The ionization behaviour and diagnostic product ions were investigated by both methods. The UHPLC/DAD-ESI-HRMS(n) method was applied for the dereplication of a plant extract. For the six standard compounds, the main fragmentation pattern consists first in the loss of the side chain in the C-8 position followed by the loss of the substituent in the C-13 position. UHPLC/HRMS analyses of hirsutinolides mainly produced sodiated molecules or [M+H-H2 O](+) ions. The high-abundance product ions at m/z 299 and 259 were established to be the characteristic diagnostic ions of the hirsutinolide core. The analysis of a P. spiralis extract further led to the identification of two putative hirsutinolides. The UHPLC/DAD-HRMS(n) method combining characteristic fragmentation patterns and the profiles of the product ions generated in the MS and MS/MS spectra is an effective technique for characterizing hirsutinolide-type SLs.

Absorbable polymer degradation responding to artificial plaque composition

Event Abstract Back to Event Absorbable polymer degradation responding to artificial plaque composition Aleer Yol1 and Ji Guo1 1 U.S. Food and Drug Adminstration, Center for Devices and Radiological Health, United States Introduction: New generation of drug-eluting stents (DES) are composed of absorbable polymers like Poly(lactic-co-glycolic acid) (PLGA). To assess the safety and efficacy of DES, it is critical to know the degradation behavior of these polymers upon stent application. It is well established that the composition of atherosclerotic vessels can vary dramatically with patients’ age and gender [1],[2]. These physical and chemical differences in the local vascular environment may impact the degradation pathway and rate. If the effect is significant, treatment with the same device, such as a DES using biodegradable polymers or a completely absorbable stents, may lead to different clinical outcomes. Although there is evidence that local environment impacts the degradation pathway, the extent of the impact has not been quantified. Our study used artificial plaques to assess potential differences in degradation of absorbable polymers with respect to known physiological differences in the composition and chemistry of atherosclerotic plaque. Materials and Methods: Poly(lactic-co-glycolic acid)with L/G 50:50, (PLGA 50) (Durect Corp), Gelatin (from bovine skin, type B; Sigma-Aldrich), Glutaraldehyde (GTA) (Fisher Scientific, 25%), Phospholipid (Avanti Polar Lipids), Cholesterol (Sigma-Aldrich), cholesteryl palmitate (Sigma-Aldrich), cholesteryl oleate (Alfa Aesar), cholesteryl linoleate (Sigma-Aldrich), Water (Fisher Scientific) and Acetonitrile (Sigma-Aldrich) were used as received. PLGA 50 films were prepared by casting 30% PLGA solution in dichloromethane at the bottom of 20 mL scintillation vials. Artificial plaque was prepared according to our previous studies [3] and was mounted on top of each PLGA film. PLGA films were degraded in the presence of artificial plaque at 37 °C and sampled weekly for analysis. PLGA degradants extracted from the artificial plaques were analyzed with an electrospray ionization (ESI) linear ion trap mass spectrometer (MS) (Thermo). Molecular weights of residual polymer films were monitored by gel permeation chromatography (GPC) (Waters). Results and Discussion: PLGA 50 films were degraded in contact with three different artificial plaque, no lipids, 0.022% lipids (w/w), and 0.034% lipids (w/w), respectively. There is no observable difference in degradation rate of PLGA films in the presence of three artificial plaques, as the silimiar molecular weights are recorded for these films at same timepoints. Though it is not feasible to measure the mass loss directly, MS analysis revealed that mass loss occurred earlier for PLGA films degraded in the presence of an artificial plaque with the highest lipid content (0.034%). We also found the major degradation products varied when of PLGA films degraded in artificial plaques with different compositions, as shown in Figure 1. At week five of degradation, the degradants with long glycolic units significantly diminished when PLGA films were degraded in artificial plaques with large amounts of lipids (Figure 1c). Conclusion: We assessed the impacts of artificial plaque composition on the degradation of PLGA 50. It is clear that plaque chemistry and composition influence the degradation behavior of absorbable polymers, such as mass loss and the amount and type of degradation products. This research will strongly facilitate the evaluation of the safety and efficacy of DES containing absorbable polymers. FDA Office of Women’s Health

Identification of Glycoside Compounds from Tobacco by High Performance Liquid Chromatography/Electrospray Ionization Linear Ion-Trap Tandem Mass Spectrometry Coupled with Electrospray Ionization Orbitrap Mass Spectrometry

In order to comprehensively screen and identify the glycoside compounds in tobacco, a simple, rapid and sensitive method of high performance liquid chromatography/electrospray ionization linear ion-trap tandem mass spectrometry (HPLC-ESI-LIT/MSn) coupled with electrospray ionization orbitrap mass spectrometry (ESI-Orbitrap-MS) was developed for the first time. As a result, twenty-two glycoside compounds, including eleven alcoholic glycosides, eight phenolic glycosides, two ester glycosides and an indole glycoside, were reliably identified from tobacco with high mass accuracy (within 5 mDa). Among them, four compounds were confirmed as novel molecules and other four compounds, as far as we know, were not reported previously in tobacco. This study provided a useful tool to identify the new structures of glycoside compounds in natural products, especially when there were no reference compounds available.

Identification of phenolic compounds in red wine extract samples and zebrafish embryos by HPLC-ESI-LTQ-Orbitrap-MS

The zebrafish embryo is a highly interesting biological model with applications in different scientific fields, such as biomedicine, pharmacology and toxicology. In this study, we used liquid chromatography/electrospray ionisation-linear ion trap quadrupole-Orbitrap-mass spectrometry (HPLC/ESI-LTQ-Orbitrap-MS) to identify the polyphenol compounds in a red wine extract and zebrafish embryos. Phenolic compounds and anthocyanin metabolites were determined in zebrafish embryos previously exposed to the red wine extract. Compounds were identified by injection in a high-resolution system (LTQ-Orbitrap) using accurate mass measurements in MS, MS2 and MS3 modes. To our knowledge, this research constitutes the first comprehensive identification of phenolic compounds in zebrafish by HPLC coupled to high-resolution mass spectrometry.

Single-run HPLC/ESI-LITMS profiling of ginsenosides in plant extracts and ginseng based products.

A rapid single-run analytical approach suitable to achieve a comprehensive characterization of ginsenosides - the main bioactive compounds present in plant materials from Panax species and ginseng-based products - was developed. The method is based on high-performance liquid chromatography coupled with electrospray positive ionization linear ion trap mass spectrometry (HPLC/ESI-LITMS). The main ions in the ESI-LITMS spectra were attributed to molecular adducts with sodium and potassium and fragments corresponding to cleavage of the glycosidic bonds. The simplicity of the approach allows laborious sample preparation and sophisticated spectral information-dependent acquisition to be avoided, and provides an opportunity for rapid screening. The method may replace existing HPLC-DAD profiling approaches. The results of this study indicate that HPLC/ESI-LITMS is applicable for quality control purposes on processed products and allows the rapid and direct identification of ginsenosides in crude plant extracts.

Analysis of breast cancer-associated glycosphingolipids using electrospray ionization-linear ion trap quadrupole mass spectrometry

Abnormal glycosphingolipids (GSLs) are expressed in many human tumors. These tumor-associated GSLs may have important roles in tumor progression. However, they are hard to be detected because of their low concentration and the limited availability of antibodies and lectins that recognize them. Thus, mass spectrometry is an effective method to analyze GSLs with high sensitivity. Here, we use electrospray ionization-linear ion trap quadrupole mass spectrometry (ESI-LTQ-MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) to determine the structure of a certain GSL in human breast cancer tissue. To obtain the breast cancer-associated GSLs, we applied relative abundance contrast of GSLs and signal-to-noise ratio (SNR) analyses. We also used α1,2 fucosidase and fucosyltransferases as tools in the structural analysis. Based on this analysis, we identified the ion with m/z 1184 molecular ion as fucosyl-lactoceramide (Fuc-LacCer) with a C16 fatty acid ceramide. Quantitative analysis of GSLs revealed both Fuc-LacCer and Globo-H increased in breast cancer tissues. However, these two breast cancer-associated GSLs had different roles. The results of SNR analysis suggested the abnormal Fuc-LacCer is specific to breast cancer. The GSL profiling of breast cancer cells showed fucosyltransferase 1 contributed to the biosynthesis of Globo-H and Fuc-LacCer. In conclusion, MS analysis identified an accumulation of Fuc-LacCer in breast cancer tissue. Our findings provide GSL profiles of human breast cancer and develop an MS method for the study of cancer-associated GSLs.