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Sample records for 252cf-plasma desorption mass

  1. Application of 252Cf plasma desorption mass spectrometry in dental research

    NASA Astrophysics Data System (ADS)

    Fritsch, Hans-Walter; Schmidt, Lothar; Köhl, Peter; Jungclas, Hartmut; Duschner, Heins

    1993-07-01

    Topically applied fluorides introduced in dental hygiene products elevate the concentration levels of fluoride in oral fluids and thus also affect chemical reactions of enamel de- and remineralisation. The chemical reactions on the surface of tooth enamel still are a subject of controversy. Here 252Cf-plasma desorption mass spectrometry and argon ion etching are used to analyse the molecular structure of the upper layes of enamel. The mass spectrum of untreated enamel is characterised by a series of cluster ions containing phosphate. It is evident that under certain conditions the molecular structure of the surface enamel is completely transformed by treatment with fluorides. The result of the degradation and precipitation processes is reflected by a total replacement of the phosphate by fluoride in the measured cluster ion distribution. Stepwise etching of the upper layers by Ar+ ions reveals the transition from a nearly pure CaF2 structure to the unchanged composition of the enamel mineral.

  2. Combination of HPLC and 252-Cf plasma desorption mass spectrometry for identifying composition of ginseng tinctures.

    PubMed

    Elkin, Y N; Makhankov, V V; Uvarova, N L; Bondarenko, P V; Zubarev, R A; Knysh, A N

    1993-03-01

    The 252-Cf plasma desorption mass spectrometry (252-Cf PDMS) determination or confirmation of the ginsenoside saponins has been proposed to investigate the composition of high performance liquid chromatography (HPLC) peaks of ginseng tinctures and galenic preparations. That ionization technique is well suitable for the analysis of natural mixtures of these saponins. The 252-Cf PD mass spectra of standard ginsenosides Rb1, Rb2, Rc, Re, Rg1, Rd, NG-R2, Z-R1 contain the peaks of two types of ions, namely, molecular adduct ions (MAI) and aglycone ions. By mass the latter may be referred to either protopanaxadiol or protopanaxatriol. The masses of MAI and aglycone ions are determined by the carbohydrate chains. The collected HPLC fractions of P ginseng tincture can be tested for content of ginsenosides. After studying two MAI peaks from the 252-Cf PD mass spectra of the basic ginsenosides, an example of distinction between two galenic preparations from different Panax has been shown. PMID:8352021

  3. Analusis by 252Cf plasma desorption mass spectrometry of Bordetella pertussis endotoxin after nitrous deamination

    NASA Astrophysics Data System (ADS)

    Deprun, C.; Karibian, D.; Caroff, M.

    1993-07-01

    Endotoxic lipopolysaccharides (LPSs) are the major components of Gram-negative bacterial outer membrane. Like many amphipathic molecules, they pose problems of heterogeneity, purity, solubility, and aggregation. Nevertheless, PDMS has recently have been applied to unmodified endotoxins composed of LPS having uip to five sugar units in their saccharide chain. The B. Pertussis LPSs, most of which have a dodecasaccharide domain, ahve been analysed by classical methods and the masses of the separate lipid and saccharide domains determined after rupture of the bond linking them. However, the acid treatment employed for these and most chemical analyses can also modify structures in the vicinity of the bond. In order to investigate this biologically-important region, the endotoxin was treated to nitrous deamination, which shortens the saccharide chain to five sugars, but preserves the acid-labile region of the LPS. The PDM spectrum of this derivative, which required new conditions for its desorption, confirmed the structure analysis and demonstrated the presence of at least four molecular species.

  4. Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

    NASA Astrophysics Data System (ADS)

    Schmidt, Lothar; Danigel, Harald; Jungclas, Hartmut

    1982-07-01

    A 252Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures.

  5. Plasma Desorption Mass Spectrometry: Coming of Age.

    ERIC Educational Resources Information Center

    Cotter, Robert J.

    1988-01-01

    Discusses the history and development of Plasma Desorption Mass Spectrometry to determine molecular weights and structures of proteins and polymers. Outlines theory, instrumentation, and sample preparation commonly used. Gives several examples of resulting spectra. (ML)

  6. Laser-desorption mass spectrometry/mass spectrometry and the mechanism of desorption ionization

    SciTech Connect

    Zakett, D.; Schoen, A.E.; Cooks, R.G.; Hemberger, P.H.

    1981-03-11

    This paper reports sucrose mass spectra obtained by combining laser desorption with mass spectrometry/mass spectrometry. Remarkable similarities in fragmentation behavior with secondary ion mass spectra (SIMS) provide evidence for mechanistic similarities between SIMS and laser desorption (LD). Attachment of alkali metals to organic molecules (cationization) is a common feature of desorption ionization. This process also occurs during laser desorption of involatile compounds which further indicates the existence of underlying similarities between LD and SIMS. Steady ion currents (several thousand ions per laser pulse) of cationized sucrose are obtained for relatively long periods (minutes).

  7. Protein surface topology-probing by selective chemical modification and mass spectrometric peptide mapping.

    PubMed Central

    Suckau, D; Mak, M; Przybylski, M

    1992-01-01

    Aminoacetylation of lysine residues and the modification of arginine by 1,2-cyclohexanedione to N7,N8-(dihydroxy-1,2-cyclohexylidene)arginine were used for probing the surface topology of hen-eggwhite lysozyme as a model protein. The molecular identification of lysine and arginine modification sites was provided by molecular weight determinations of modified and unmodified tryptic peptide mixtures (peptide mapping) using 252Cf plasma desorption mass spectrometry. At conditions of limited chemical modification, mass-spectrometric peptide-mapping analyses of lysozyme derivatives enabled the direct assignment of relative reactivities of lysine and arginine residues at different reaction times and reagent concentrations. The relative reactivities of lysine residues showed a direct correlation with their surface accessibilities from x-ray structure data. For the reaction with 1,2-cyclohexanedione, a selective modification at Arg-5, -125, -112, and -73 was identified, and an inverse correlation of relative reactivities with the surface accessibility ratios of the N7- and the N8-guanidino functions was obtained. By examination of the x-ray structural data of lysozyme, this selective modification was attributed to intramolecular catalysis because of the presence of neighboring proton acceptor groups, such as the Asp-119 carboxylate group for Arg-125 and the Trp-123 and Arg-125 carbonyl groups for Arg-5. PMID:1608973

  8. Laser desorption mass spectrometry for biomolecule detection and its applications

    NASA Astrophysics Data System (ADS)

    Winston Chen, C. H.; Sammartano, L. J.; Isola, N. R.; Allman, S. L.

    2001-08-01

    During the past few years, we developed and used laser desorption mass spectrometry for biomolecule detections. Matrix-assisted laser desorption/ionization (MALDI) was successfully used to detect DNA fragments with the size larger than 3000 base pairs. It was also successfully used to sequence DNA with both enzymatic and chemical degradation methods to produce DNA ladders. We also developed MALDI with fragmentation for direct DNA sequencing for short DNA probes. Since laser desorption mass spectrometry for DNA detection has the advantages of fast speed and no need of labeling, it has a great potential for molecular diagnosis for disease and person identification by DNA fingerprinting. We applied laser desorption mass spectrometry to succeed in the diagnosis of cystic fibrosis and several other nerve degenerative diseases such as Huntington's disease. We also succeeded in demonstrating DNA typing for forensic applications.

  9. Charge Assisted Laser Desorption/Ionization Mass Spectrometry of Droplets

    PubMed Central

    Jorabchi, Kaveh; Westphall, Michael S.; Smith, Lloyd M.

    2008-01-01

    We propose and evaluate a new mechanism to account for analyte ion signal enhancement in ultraviolet-laser desorption mass spectrometry of droplets in the presence of corona ions. Our new insights are based on timing control of corona ion production, laser desorption, and peptide ion extraction achieved by a novel pulsed corona apparatus. We demonstrate that droplet charging rather than gas-phase ion-neutral reactions is the major contributor to analyte ion generation from an electrically isolated droplet. Implications of the new mechanism, termed charge assisted laser desorption/ionization (CALDI), are discussed and contrasted to those of the laser desorption atmospheric pressure chemical ionization method (LD-APCI). It is also demonstrated that analyte ion generation in CALDI occurs with external electric fields about one order of magnitude lower than those needed for atmospheric pressure matrix assisted laser desorption/ionization or electrospray ionization of droplets. PMID:18387311

  10. Desorption electrospray ionization-mass spectrometry of proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Desorption electrospray ionization-mass spectrometry (DESI-MS) was evaluated for the detection of proteins ranging in molecular mass from 12 to 66 kDa. Proteins were uniformly deposited on a solid surface without pretreatment and analyzed with a DESI source coupled to a quadrupole ion trap mass spec...

  11. Desorption electrospray ionization mass spectrometry of intact bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Desorption electrospray ionization (DESI) mass spectrometry (MS) was used to differentiate 7 bacterial species based on their measured DESI-mass spectral profile. Both Gram positive and Gram negative bacteria were tested and included Escherichia coli, Staphyloccocus aureus, Enterococcus sp., Bordete...

  12. Quantitative matrix-assisted laser desorption/ionization mass spectrometry

    PubMed Central

    Roder, Heinrich; Hunsucker, Stephen W.

    2008-01-01

    This review summarizes the essential characteristics of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF MS), especially as they relate to its applications in quantitative analysis. Approaches to quantification by MALDI-TOF MS are presented and published applications are critically reviewed. PMID:19106161

  13. Laser desorption postionization mass spectrometry imaging of biological targets.

    PubMed

    Akhmetov, Artem; Bhardwaj, Chhavi; Hanley, Luke

    2015-01-01

    Laser desorption photoionization mass spectrometry (LDPI-MS) utilizes two separate light sources for desorption and photoionization of species from a solid surface. This technique has been applied to study a wide variety of molecular analytes in biological systems, but is not yet available in commercial instruments. For this reason, a generalized protocol is presented here for the use of LDPI-MS imaging to detect small molecules within intact biological samples. Examples are provided here for LDPI-MS imaging of an antibiotic within a tooth root canal and a metabolite within a coculture bacterial biofilm. PMID:25361678

  14. Laser desorption in an ion trap mass spectrometer

    SciTech Connect

    Eiden, G.C.; Cisper, M.E.; Alexander, M.L.; Hemberger, P.H.; Nogar, N.S.

    1993-02-01

    Laser desorption in a ion-trap mass spectrometer shows significant promise for both qualitative and trace analysis. Several aspects of this methodology are discussed in this work. We previously demonstrated the generation of both negative and positive ions by laser desorption directly within a quadrupole ion trap. In the present work, we explore various combinations of d.c., r.f., and time-varying fields in order to optimize laser generated signals. In addition, we report on the application of this method to analyze samples containing compounds such as amines, metal complexes, carbon clusters, and polynuclear aromatic hydrocarbons. In some cases the ability to rapidly switch between positive and negative ion modes provides sufficient specificity to distinguish different compounds of a mixture with a single stage of mass spectrometry. In other experiments, we combined intensity variation studies with tandem mass spectrometry experiments and positive and negative ion detection to further enhance specificity.

  15. Laser desorption lamp ionization source for ion trap mass spectrometry.

    PubMed

    Wu, Qinghao; Zare, Richard N

    2015-01-01

    A two-step laser desorption lamp ionization source coupled to an ion trap mass spectrometer (LDLI-ITMS) has been constructed and characterized. The pulsed infrared (IR) output of an Nd:YAG laser (1064 nm) is directed to a target inside a chamber evacuated to ~15 Pa causing desorption of molecules from the target's surface. The desorbed molecules are ionized by a vacuum ultraviolet (VUV) lamp (filled with xenon, major wavelength at 148 nm). The resulting ions are stored and detected in a three-dimensional quadrupole ion trap modified from a Finnigan Mat LCQ mass spectrometer operated at a pressure of ≥ 0.004 Pa. The limit of detection for desorbed coronene molecules is 1.5 pmol, which is about two orders of magnitude more sensitive than laser desorption laser ionization mass spectrometry using a fluorine excimer laser (157 nm) as the ionization source. The mass spectrum of four standard aromatic compounds (pyrene, coronene, rubrene and 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine (OPC)) shows that parent ions dominate. By increasing the infrared laser power, this instrument is capable of detecting inorganic compounds. PMID:25601688

  16. Characterization of polymer decomposition products by laser desorption mass spectrometry

    NASA Technical Reports Server (NTRS)

    Pallix, Joan B.; Lincoln, Kenneth A.; Miglionico, Charles J.; Roybal, Robert E.; Stein, Charles; Shively, Jon H.

    1993-01-01

    Laser desorption mass spectrometry has been used to characterize the ash-like substances formed on the surfaces of polymer matrix composites (PMC's) during exposure on LDEF. In an effort to minimize fragmentation, material was removed from the sample surfaces by laser desorption and desorbed neutrals were ionized by electron impact. Ions were detected in a time-of-flight mass analyzer which allows the entire mass spectrum to be collected for each laser shot. The method is ideal for these studies because only a small amount of ash is available for analysis. Three sets of samples were studied including C/polysulfone, C/polyimide and C/phenolic. Each set contains leading and trailing edge LDEF samples and their respective controls. In each case, the mass spectrum of the ash shows a number of high mass peaks which can be assigned to fragments of the associated polymer. These high mass peaks are not observed in the spectra of the control samples. In general, the results indicate that the ash is formed from decomposition of the polymer matrix.

  17. Unexpected Analyte Oxidation during Desorption Electrospray Ionization - Mass Spectrometry

    SciTech Connect

    Pasilis, Sofie P; Kertesz, Vilmos; Van Berkel, Gary J

    2008-01-01

    During the analysis of surface spotted analytes using desorption electrospray ionization mass spectrometry (DESI-MS), abundant ions are sometimes observed that appear to be the result of oxygen addition reactions. In this investigation, the effect of sample aging, the ambient lab environment, spray voltage, analyte surface concentration, and surface type on this oxidative modification of spotted analytes, exemplified by tamoxifen and reserpine, during analysis by desorption electrospray ionization mass spectrometry was studied. Simple exposure of the samples to air and to ambient lighting increased the extent of oxidation. Increased spray voltage lead also to increased analyte oxidation, possibly as a result of oxidative species formed electrochemically at the emitter electrode or in the gas - phase by discharge processes. These oxidative species are carried by the spray and impinge on and react with the sampled analyte during desorption/ionization. The relative abundance of oxidized species was more significant for analysis of deposited analyte having a relatively low surface concentration. Increasing spray solvent flow rate and addition of hydroquinone as a redox buffer to the spray solvent were found to decrease, but not entirely eliminate, analyte oxidation during analysis. The major parameters that both minimize and maximize analyte oxidation were identified and DESI-MS operational recommendations to avoid these unwanted reactions are suggested.

  18. Improved Imaging Resolution in Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Kertesz, Vilmos; Van Berkel, Gary J

    2008-01-01

    Imaging resolution of desorption electrospray ionization mass spectrometry (DESI-MS) was investigated using printed patterns on paper and thin-layer chromatography (TLC) plate surfaces. Resolution approaching 40 m was achieved with a typical DESI-MS setup, which is approximately 5 times better than the best resolution reported previously. This improvement was accomplished with careful control of operational parameters (particularly spray tip-to-surface distance, solvent flow rate, and spacing of lane scans). Also, an appropriately strong analyte/surface interaction and uniform surface texture on the size scale no larger that the desired imaging resolution were required to achieve this resolution. Overall, conditions providing the smallest possible effective desorption/ionization area in the DESI impact plume region and minimizing the analyte redistribution on the surface during analysis led to the improved DESI-MS imaging resolution.

  19. Laser desorption mass spectrometry for DNA analysis and sequencing

    SciTech Connect

    Chen, C.H.; Taranenko, N.I.; Tang, K.; Allman, S.L.

    1995-03-01

    Laser desorption mass spectrometry has been considered as a potential new method for fast DNA sequencing. Our approach is to use matrix-assisted laser desorption to produce parent ions of DNA segments and a time-of-flight mass spectrometer to identify the sizes of DNA segments. Thus, the approach is similar to gel electrophoresis sequencing using Sanger`s enzymatic method. However, gel, radioactive tagging, and dye labeling are not required. In addition, the sequencing process can possibly be finished within a few hundred microseconds instead of hours and days. In order to use mass spectrometry for fast DNA sequencing, the following three criteria need to be satisfied. They are (1) detection of large DNA segments, (2) sensitivity reaching the femtomole region, and (3) mass resolution good enough to separate DNA segments of a single nucleotide difference. It has been very difficult to detect large DNA segments by mass spectrometry before due to the fragile chemical properties of DNA and low detection sensitivity of DNA ions. We discovered several new matrices to increase the production of DNA ions. By innovative design of a mass spectrometer, we can increase the ion energy up to 45 KeV to enhance the detection sensitivity. Recently, we succeeded in detecting a DNA segment with 500 nucleotides. The sensitivity was 100 femtomole. Thus, we have fulfilled two key criteria for using mass spectrometry for fast DNA sequencing. The major effort in the near future is to improve the resolution. Different approaches are being pursued. When high resolution of mass spectrometry can be achieved and automation of sample preparation is developed, the sequencing speed to reach 500 megabases per year can be feasible.

  20. Counting Molecules by Desorption Ionization and Mass Spectrometry/Mass Spectrometry.

    ERIC Educational Resources Information Center

    Cooks, R. G.; Busch, K. L.

    1982-01-01

    Discusses two newer methods in mass spectrometry and shows how they can increase signal and signal-to-noise ratios, respectively. The first method, desorption ionization (DI), increases sensitivity while the second method, mass spectrometry/mass spectrometry (MS/MS), increases specificity. Together, the two methods offer improved analytical…

  1. The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

    NASA Astrophysics Data System (ADS)

    Rogers, Kevin; Milnes, John; Gormally, John

    1993-02-01

    Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

  2. Californium-252 plasma desorption with Fourier transform mass spectroscopy

    SciTech Connect

    Loo, J.A; Williams, E.R.; Amster, I.J.; Furlong, J.J.P.; Wang, B.H.; McLafferty, F.W.; Chait, B.T.; Field, F.H.

    1987-01-01

    Plasma desorption (PD) such, as that induced by the 100-MeV fission products of /sup 252/Cf, is a particularly promising ionization method for large molecules, yielding molecular ion species even from trypsin, molecular weight 23,463. Further, with trypsin using nitrocellulose as the substrate, (M + 3H)/sup 3 +/ is the most abundant molecular ion species and (M + 6H)/sup 6 +/ is measurable, which greatly extends the mass values (m) observable for instruments with an upper m/z limit (z = number of charges). However, a 50-..mu..Ci /sup 252/Cf source only produces 55,000 fissions s/sup -1/, yielding ion currents that are generally much too low for scanning instruments. An instrument with unusual capabilities for these, as well as for simultaneous ion detection over a wide mass range, is the Fourier transform (FT) mass spectrometer. With FTMS, Hunt has measured (M + H)/sup +/ ions of cytochrome c, molecular weight 12,384, ionized in an exterior fast-atom-bombardment source. Here the authors describe techniques for obtaining PD/FT mass spectra for a variety of compounds with abundant molecular ion species of masses as high as 2016 (alamethicin).

  3. Laser Desorption Mass Spectrometry for DNA Sequencing and Analysis

    NASA Astrophysics Data System (ADS)

    Chen, C. H. Winston; Taranenko, N. I.; Golovlev, V. V.; Isola, N. R.; Allman, S. L.

    1998-03-01

    Rapid DNA sequencing and/or analysis is critically important for biomedical research. In the past, gel electrophoresis has been the primary tool to achieve DNA analysis and sequencing. However, gel electrophoresis is a time-consuming and labor-extensive process. Recently, we have developed and used laser desorption mass spectrometry (LDMS) to achieve sequencing of ss-DNA longer than 100 nucleotides. With LDMS, we succeeded in sequencing DNA in seconds instead of hours or days required by gel electrophoresis. In addition to sequencing, we also applied LDMS for the detection of DNA probes for hybridization LDMS was also used to detect short tandem repeats for forensic applications. Clinical applications for disease diagnosis such as cystic fibrosis caused by base deletion and point mutation have also been demonstrated. Experimental details will be presented in the meeting. abstract.

  4. Laser desorption mass spectrometry for point mutation detection

    SciTech Connect

    Taranenko, N.I.; Chung, C.N.; Zhu, Y.F.

    1996-12-31

    A point mutation can be associated with the pathogenesis of inherited or acquired diseases. Laser desorption mass spectrometry coupled with allele specific polymerase chain reaction (PCR) was first used for point mutation detection. G551D is one of several mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene present in 1-3% of the mutant CFTR alleles in most European populations. In this work, two different approaches were pursued to detect G551D point mutation in the cystic fibrosis gene. The strategy is to amplify the desired region of DNA template by PCR using two primers that overlap one base at the site of the point mutation and which vary in size. If the two primers based on the normal sequence match the target DNA sequence, a normal PCR product will be produced. However, if the alternately sized primers that match the mutant sequence recognize the target DNA, an abnormal PCR product will be produced. Thus, the mass spectrometer can be used to identify patients that are homozygous normal, heterozygous for a mutation or homozygous abnormal at a mutation site. Another approach to identify similar mutations is the use of sequence specific restriction enzymes which respond to changes in the DNA sequence. Mass spectrometry is used to detect the length of the restriction fragments by digestion of a PCR generated target fragment. 21 refs., 10 figs., 2 tabs.

  5. Laser desorption mass spectrometry for point mutation detection

    SciTech Connect

    Taranenko, N.I.; Chung, C.N.; Zhu, Y.F.

    1996-10-01

    A point mutation can be associated with the pathogenesis of inherited or acquired diseases. Laser desorption mass spectrometry coupled with allele specific polymerase chain reaction (PCR) was first used for point mutation detection. G551D is one of several mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene present in 1-3% of the mutant CFTR alleles in most European populations. In this work, two different approaches were pursued to detect G551D point mutation in the cystic fibrosis gene. The strategy is to amplify the desired region of DNA template by PCR using two primers that overlap one base at the site of the point mutation and which vary in size. If the two primers based on the normal sequence match the target DNA sequence, a normal PCR product will be produced. However, if the alternately sized primers that match the mutant sequence recognize the target DNA, an abnormal PCR product will be produced. Thus, the mass spectrometer can be used to identify patients that are homozygous normal, heterozygous for a mutation or homozygous abnormal at a mutation site. Another approach to identify similar mutations is the use of sequence specific restriction enzymes which respond to changes in the DNA sequence. Mass spectrometry is used to detect the length of the restriction fragments generated by digestion of a PCR generated target fragment. 21 refs., 10 figs., 2 tabs.

  6. Exploring the high-mass components of humic acid by laser desorption ionization mass spectrometry.

    PubMed

    Chilom, Gabriela; Chilom, Ovidiu; Rice, James A

    2008-05-01

    Leonardite and Elliot soil humic acids have been analyzed by laser desorption ionization mass spectrometry (LDI MS) in the m/z 4000-200,000 range. Positive ion mass spectra for each humic acid obtained under optimum conditions showed a broad high-mass distribution between m/z 20,000 and 80,000. The dependence of the mass distribution on instrumental parameters and solution conditions was used to investigate the nature of the high-mass peaks from humic acid spectra. Our data suggests that macromolecular ions and humic acid aggregates have the same probability of occurrence while cluster ion formation has a low probability of occurrence. PMID:18421699

  7. Multistage Reactive Transmission-Mode Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Peters, Kevin C; Comi, Troy J; Perry, Richard H

    2015-09-01

    Elucidating reaction mechanisms is important for advancing many areas of science such as catalyst development. It is often difficult to probe fast reactions at ambient conditions with high temporal resolution. In addition, systems involving reagents that cross-react require analytical methods that can minimize interaction time and specify their order of introduction into the reacting system. Here, we explore the utility of transmission mode desorption electrospray ionization (TM-DESI) for reaction monitoring by directing a microdroplet spray towards a series of meshes with micrometer-sized openings coated with reagents, an approach we call multistage reactive TM-DESI (TM (n) -DESI, where n refers to the number of meshes; n = 2 in this report). Various stages of the reaction are initiated at each mesh surface, generating intermediates and products in microdroplet reaction vessels traveling towards the mass spectrometer. Using this method, we investigated the reactivity of iron porphyrin catalytic hydroxylation of propranolol and other substrates. Our experimental results indicate that TM (n) -DESI provides the ability to spatially separate reagents and control their order of introduction into the reacting system, thereby minimizing unwanted reactions that lead to catalyst deactivation and degradation products. In addition, comparison with DESI-MS analyses (the Zare and Latour laboratories published results suggesting accessible reaction times <1 ms) of the reduction of dichlorophenolindophenol by L-ascorbic acid suggest that TM (1) -DESI can access reaction times less than 1 ms. Multiple meshes allow sequential stages of desorption/ionization per MS scan, increasing the number of analytes and reactions that can be characterized in a single experiment. PMID:26091888

  8. Imaging of Biological Tissues by Desorption Electrospray Ionization Mass Spectrometry

    PubMed Central

    Fernández, Facundo M.

    2013-01-01

    Mass spectrometry imaging (MSI) provides untargeted molecular information with the highest specificity and spatial resolution for investigating biological tissues at the hundreds to tens of microns scale. When performed under ambient conditions, sample pre-treatment becomes unnecessary, thus simplifying the protocol while maintaining the high quality of information obtained. Desorption electrospray ionization (DESI) is a spray-based ambient MSI technique that allows for the direct sampling of surfaces in the open air, even in vivo. When used with a software-controlled sample stage, the sample is rastered underneath the DESI ionization probe, and through the time domain, m/z information is correlated with the chemical species' spatial distribution. The fidelity of the DESI-MSI output depends on the source orientation and positioning with respect to the sample surface and mass spectrometer inlet. Herein, we review how to prepare tissue sections for DESI imaging and additional experimental conditions that directly affect image quality. Specifically, we describe the protocol for the imaging of rat brain tissue sections by DESI-MSI. PMID:23892773

  9. The laser desorption/laser ionization mass spectra of some indole derivatives and alkaloids

    NASA Astrophysics Data System (ADS)

    Rogers, Kevin; Milnes, John; Gormally, John

    1992-06-01

    The laser desorption and laser ionization mass spectra of some indole derivatives and alkaloids are described with particular reference to their modes of fragmentation. Mass spectra of yohimbine, reserpine, quinine and quinidine are presented. Full experimental details are given.

  10. Solvent jet desorption capillary photoionization-mass spectrometry.

    PubMed

    Haapala, Markus; Teppo, Jaakko; Ollikainen, Elisa; Kiiski, Iiro; Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

    2015-03-17

    A new ambient mass spectrometry method, solvent jet desorption capillary photoionization (DCPI), is described. The method uses a solvent jet generated by a coaxial nebulizer operated at ambient conditions with nitrogen as nebulizer gas. The solvent jet is directed onto a sample surface, from which analytes are extracted into the solvent and ejected from the surface in secondary droplets formed in collisions between the jet and the sample surface. The secondary droplets are directed into the heated capillary photoionization (CPI) device, where the droplets are vaporized and the gaseous analytes are ionized by 10 eV photons generated by a vacuum ultraviolet (VUV) krypton discharge lamp. As the CPI device is directly connected to the extended capillary inlet of the MS, high ion transfer efficiency to the vacuum of MS is achieved. The solvent jet DCPI provides several advantages: high sensitivity for nonpolar and polar compounds with limit of detection down to low fmol levels, capability of analyzing small and large molecules, and good spatial resolution (250 μm). Two ionization mechanisms are involved in DCPI: atmospheric pressure photoionization, capable of ionizing polar and nonpolar compounds, and solvent assisted inlet ionization capable of ionizing larger molecules like peptides. The feasibility of DCPI was successfully tested in the analysis of polar and nonpolar compounds in sage leaves and chili pepper. PMID:25715054

  11. Laser desorption mass spectrometry for fast DNA analysis

    SciTech Connect

    Chen, C.H.; Ch`ang, L.Y.; Taranenko, N.I.; Allman, S.L.; Tang, K.; Matteson, K.J.

    1995-09-01

    During the past few years, major effort has been directed toward developing mass spectrometry to measure biopolymers because of the great potential benefit to biomedical research. Hellenkamp and his co-workers were the first to report that large polypeptide molecules can be ionized and detected without significant fragmentation when a greater number of nicotinic acid molecules are used as a matrix. This method is now well known as matrix-assisted laser desorption/ionization (MALDI). Since then, various groups have reported measurements of very large proteins by MALDI. Reliable protein analysis by MALDI is more or less well established. However, the application of MALDI to nucleic acids analysis has been found to be much more difficult. Most research on the measurement of nucleic acid by MALDI were stimulated by the Human Genome Project. Up to now, the only method for reliable routine analysis of nucleic acid is gel electrophoresis. Different sizes of nucleic acids can be separated in gel medium when a high electric field is applied to the gel. However, the time needed to separate different sizes of DNA segments usually takes from several minutes to several hours. If MALDI can be successfully used for nucleic acids analysis, the analysis time can be reduced to less than I millisecond. In addition, no tagging with radioactive materials or chemical dyes is needed. In this work, we will review recent progress related to MALDI for DNA analysis.

  12. Liquid Beam Ion Desorption Mass Spectrometry for Evaluating CASSINI Data

    NASA Astrophysics Data System (ADS)

    Stolz, Ferdinand; Reviol, Rene; Srama, Ralf; Trieloff, Mario; Postberg, Frank; Abel, Bernd

    2013-04-01

    Saturn's moon Enceladus emits plumes of ice particles from an area near its south pole which are detected and chemically analyzed by the Cosmic Dust Analyzer (CDA) on board the CASSINI spacecraft. Studying these ice particles provides unique insights into Enceladus geological properties. Technically the CDA is a time-of-flight mass spectrometer which delivers mass spectra of the particles and their fragments. Since interpretation of the available CDA data is particularly challenging we employ a laboratory experiment to imitate experimental conditions in space. Key part of our experimental setup is a micron-sized water beam in high vacuum. This beam is rapidly heated up by an infrared laser pulse, which is tuned to excite the OH-stretch vibration of water molecules. This causes the water beam to dissipate into small droplets, some of which carry a net charge even though the laser energy is well below the molecular ionisation energy. The charged droplets are then analyzed in a time-of-flight mass spectrometer. With this experimental setup we successfully simulated the space born ice particles measured at Enceladus. By varying the laser intensity in our experiments, we can vary the amount of energy deposited in the liquid beam, and thus model different particle velocities. Also, variation of solute concentration in the water beam provides valuable information about ice particle composition. Some examples for anorganic solutes studied so far are sodium chloride, ammonia and hydrogen sulfite. A special feature of our experimental technique is that desorption of particles from the liquid beam is particularly soft. This is explained by the fact that all laser energy is absorbed by the water molecules. In this way molecular bonds of solutes stay intact and molecular solutes are transferred into the droplet phase without getting destroyed. This is particularly interesting in the context of analyzing organic compounds - some of which have been detected at Enceladus. Using

  13. Desorption electrospray ionisation mass spectrometry and tandem mass spectrometry of low molecular weight synthetic polymers.

    PubMed

    Jackson, Anthony T; Williams, Jonathan P; Scrivens, James H

    2006-01-01

    A range of low molecular weight synthetic polymers has been characterised by means of desorption electrospray ionisation (DESI) combined with both mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Accurate mass experiments were used to aid the structural determination of some of the oligomeric materials. The polymers analysed were poly(ethylene glycol) (PEG), polypropylene glycol (PPG), poly(methyl methacrylate) (PMMA) and poly(alpha-methyl styrene). An application of the technique for characterisation of a polymer used as part of an active ingredient in a pharmaceutical tablet is described. The mass spectra and tandem mass spectra of all of the polymers were obtained in seconds, indicating the sensitivity of the technique. PMID:16912984

  14. Desorption Mass Spectrometry for Nonvolatile Compounds Using an Ultrasonic Cutter

    NASA Astrophysics Data System (ADS)

    Habib, Ahsan; Ninomiya, Satoshi; Chen, Lee Chuin; Usmanov, Dilshadbek T.; Hiraoka, Kenzo

    2014-07-01

    In this work, desorption of nonvolatile analytes induced by friction was studied. The nonvolatile compounds deposited on the perfluoroalkoxy substrate were gently touched by an ultrasonic cutter oscillating with a frequency of 40 kHz. The desorbed molecules were ionized by a dielectric barrier discharge (DBD) ion source. Efficient desorption of samples such as drugs, pharmaceuticals, amino acids, and explosives was observed. The limits of detection for these compounds were about 1 ng. Many compounds were detected in their protonated forms without undergoing significant fragmentation. When the DBD was off, no ions for the neutral samples could be detected, meaning that only desorption along with little ionization took place by the present technique.

  15. Sample-matrix effects in infrared laser neutral desorption, multiphoton-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beavis, R. C.; Lindner, J.; Grotemeyer, J.; Schlag, E. W.

    1988-05-01

    Sample-matrix effects in laser evaporation of intact neutral molecules (LEIM) prior to multiphoton ionization mass spectrometry (MUPI MS) are studied. The results show that a strong influence exists in adding matrix materials to the sample upon the desorption step. Using sugars as matrix leads to a suppression of pyrolysis products in small peptides by the laser desorption. As a result mass spectrometric signals due to the pyrolysis products are avoided.

  16. A Combined Desorption Ionization by Charge Exchange (DICE) and Desorption Electrospray Ionization (DESI) Source for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chan, Chang-Ching; Bolgar, Mark S.; Miller, Scott A.; Attygalle, Athula B.

    2011-01-01

    A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H]+ or [M + metal]+ ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies.

  17. A combined desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) source for mass spectrometry.

    PubMed

    Chan, Chang-Ching; Bolgar, Mark S; Miller, Scott A; Attygalle, Athula B

    2011-01-01

    A source that couples the desorption ionization by charge exchange (DICE) and desorption electrospray ionization (DESI) techniques together was demonstrated to broaden the range of compounds that can be analyzed in a single mass spectrometric experiment under ambient conditions. A tee union was used to mix the spray reagents into a partially immiscible blend before this mixture was passed through a conventional electrospray (ES) probe capillary. Using this technique, compounds that are ionized more efficiently by the DICE method and those that are ionized better with the DESI procedure could be analyzed simultaneously. For example, hydroquinone, which is not detected when subjected to DESI-MS in the positive-ion generation mode, or the sodium adduct of guaifenesin, which is not detected when examined by DICE-MS, could both be detected in one experiment when the two techniques were combined. The combined technique was able to generate the molecular ion, proton and metal adduct from the same compound. When coupled to a tandem mass spectrometer, the combined source enabled the generation of product ion spectra from the molecular ion and the [M + H](+) or [M + metal](+) ions of the same compound without the need to physically change the source from DICE to DESI. The ability to record CID spectra of both the molecular ion and adduct ions in a single mass spectrometric experiment adds a new dimension to the array of mass spectrometric methods available for structural studies. PMID:21472555

  18. Speciation of arsenic oxides using laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Allen, T M; Bezabeh, D Z; Smith, C H; McCauley, E M; Jones, A D; Chang, D P; Kennedy, I M; Kelly, P B

    1996-11-15

    Positive and negative ion mass spectra of arsenic trioxide (As2O3) and arsenic pentaoxide (As2O5) have been obtained by single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 nm was used for the simultaneous desorption and ionization of the solid sample. High-mass cluster ions that are unique to the oxidation state of each oxide sample appear in the negative ion mass spectra. The As2O3 produces As3O5-, while the As2O5 yields As3O8-. The formation of unique negative cluster ions presents the capability for arsenic oxidation state speciation by laser desorption/ionization mass spectrometry. The ability of time-of-flight mass spectrometry to examine the relative amounts of each arsenic oxide present in a series of mixtures is discussed. Application of our speciation technique to a model incinerator sample is demonstrated. PMID:8916457

  19. Spatially resolved thermal desorption/ionization coupled with mass spectrometry

    SciTech Connect

    Jesse, Stephen; Van Berkel, Gary J; Ovchinnikova, Olga S

    2013-02-26

    A system and method for sub-micron analysis of a chemical composition of a specimen are described. The method includes providing a specimen for evaluation and a thermal desorption probe, thermally desorbing an analyte from a target site of said specimen using the thermally active tip to form a gaseous analyte, ionizing the gaseous analyte to form an ionized analyte, and analyzing a chemical composition of the ionized analyte. The thermally desorbing step can include heating said thermally active tip to above 200.degree. C., and positioning the target site and the thermally active tip such that the heating step forms the gaseous analyte. The thermal desorption probe can include a thermally active tip extending from a cantilever body and an apex of the thermally active tip can have a radius of 250 nm or less.

  20. Surface-assisted laser desorption ionization mass spectrometry techniques for application in forensics.

    PubMed

    Guinan, Taryn; Kirkbride, Paul; Pigou, Paul E; Ronci, Maurizio; Kobus, Hilton; Voelcker, Nicolas H

    2015-01-01

    Matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) is an excellent analytical technique for the rapid and sensitive analysis of macromolecules (>700 Da), such as peptides, proteins, nucleic acids, and synthetic polymers. However, the detection of smaller organic molecules with masses below 700 Da using MALDI-MS is challenging due to the appearance of matrix adducts and matrix fragment peaks in the same spectral range. Recently, nanostructured substrates have been developed that facilitate matrix-free laser desorption ionization (LDI), contributing to an emerging analytical paradigm referred to as surface-assisted laser desorption ionization (SALDI) MS. Since SALDI enables the detection of small organic molecules, it is rapidly growing in popularity, including in the field of forensics. At the same time, SALDI also holds significant potential as a high throughput analytical tool in roadside, work place and athlete drug testing. In this review, we discuss recent advances in SALDI techniques such as desorption ionization on porous silicon (DIOS), nano-initiator mass spectrometry (NIMS) and nano assisted laser desorption ionization (NALDI™) and compare their strengths and weaknesses with particular focus on forensic applications. These include the detection of illicit drug molecules and their metabolites in biological matrices and small molecule detection from forensic samples including banknotes and fingerprints. Finally, the review highlights recent advances in mass spectrometry imaging (MSI) using SALDI techniques. PMID:24916100

  1. Electrospray-assisted laser desorption/ionization mass spectrometry for direct ambient analysis of solids.

    PubMed

    Shiea, Jentaie; Huang, Min-Zon; Hsu, Hsiu-Jung; Lee, Chi-Yang; Yuan, Cheng-Hui; Beech, Iwona; Sunner, Jan

    2005-01-01

    A new method of electrospray-assisted laser desorption/ionization (ELDI) mass spectrometry, which combines laser desorption with post-ionization by electrospray, was applied to rapid analysis of solid materials under ambient conditions. Analytes were desorbed from solid metallic and insulating substrata using a pulsed nitrogen laser. Post-ionization produced high-quality mass spectra characteristic of electrospray, including protein multiple charging. For the first time, mass spectra of intact proteins were obtained using laser desorption without adding a matrix. Bovine cytochrome c and an illicit drug containing methaqualone were chosen in this study to demonstrate the applicability of ELDI to the analysis of proteins and synthetic organic compounds. PMID:16299699

  2. Laser desorption and matrix-assisted laser desorption/ionization mass spectrometry of 29-kDa Au:SR cluster compounds.

    PubMed

    Schaaff, T Gregory

    2004-11-01

    Positive and negative ions generated by laser-based ionization methods from three gold:thiolate cluster compounds are mass analyzed by time-of-flight mass spectrometry. The three compounds have similar inorganic core masses ( approximately 29 kDa, approximately 145 Au atoms) but different n-alkanethiolate ligands associated with each cluster compound (Au:SR, R = butane, hexane, dodecane). Irradiation of neat films (laser desorption/ionization) and films generated by dilution of the cluster compounds in an organic acid matrix (matrix-assisted laser desorption/ionization) with a nitrogen laser (337 nm) produced distinct ion abundances that are relevant to different structural aspects of the cluster compound. Laser desorption/ionization of neat Au:SR compound films produces ions consistent with the inorganic core mass (i.e., devoid of original hydrocarbon content). Matrix-assisted laser desorption/ionization produces either ions with m/z values consistent with the core mass of the cluster compounds or ions with m/z values consistent with the approximate molecular weight of the cluster compounds, depending on ionization conditions. The ion abundances, and ionization conditions under which they are detected, provide insight into desorption/ionization processes for these unique cluster compounds as well as other analytes typically studied by matrix-assisted laser desorption/ionization. PMID:15516109

  3. High-speed tandem mass spectrometric in situ imaging by nanospray desorption electrospray ionization mass spectrometry.

    PubMed

    Lanekoff, Ingela; Burnum-Johnson, Kristin; Thomas, Mathew; Short, Joshua; Carson, James P; Cha, Jeeyeon; Dey, Sudhansu K; Yang, Pengxiang; Prieto Conaway, Maria C; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis of the fragment ions (m/Δm = 17 500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of a large number of metabolites and lipids from 92 selected m/z windows (±1 Da) with a spatial resolution of better than 150 μm. Mouse uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pretreatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 μm/s, while higher-energy collision-induced dissociation (HCD) spectra were acquired for a targeted inclusion list of 92 m/z values at a rate of ∼6.3 spectra/s. Molecular ions and their corresponding fragments, separated by high-resolution mass analysis, were assigned on the basis of accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric and isomeric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isomeric and isobaric phospholipids that are difficult to separate in full-scan mode. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules. PMID:24040919

  4. High-Speed Tandem Mass Spectrometric in Situ Imaging by Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Short, Joshua TL; Carson, James P.; Cha, Jeeyeon; Dey, Sudhansu K.; Yang, Pengxiang; Prieto Conaway, Maria C.; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis (m/m=17,500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of more than 300 molecules from 92 selected m/z windows (± 1 Da) with a spatial resolution of better than 150 um. Uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pre-treatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 um/s while acquiring higher-energy collision-induced dissociation (HCD) spectra for a targeted inclusion list of 92 m/z values at a rate of ~6.3 spectra/s. Molecular ions and their corresponding fragments, separated using high-resolution mass analysis, were assigned based on accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isobaric sodium and potassium adducts of phospholipids. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules.

  5. Novel sampling methods for use with thermal desorption ion trap mass spectrometry

    SciTech Connect

    Barshick, S.A.; Buchanan, M.V.

    1994-12-31

    Novel sampling approaches have been investigated to improve the analytical utility of thermal desorption Direct Sampling Ion Trap Mass Spectrometry (DSITMS). Because DSITMS involves the direct introduction of samples into an ion trap mass spectrometer, problems with detection capabilities (sensitivity and selectivity) can often occur when performing trace analysis in complex matrices. Various sampling approaches have been evaluated to improve thermal desorption detection capabilities and to extend the utilities of DSITMS methodologies without significantly increasing analysis times or the cost-effectiveness of DSITMS methods. Three sampling approaches have been investigated including solid phase microextraction (SPME), solid phase extraction columns (SPEC), and purge and trap.

  6. Fossil fuel characterization using laser desorption mass spectrometry: Applications and limitations

    SciTech Connect

    Hunt, J.E.; Winans, R.E.

    1995-08-01

    Laser desorption mass spectroscopy (LDMS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI) are applicable to the high molecular weight compounds in fossil fuels which resist intact ionization. LD or MALDI of coals and extracts do not show reproducible ion intensity over mass 2000. This paper describes the scope and limitations of LD and MALD in time-of-flight mass spectrometers applied to high molecular weight molecules such as proteins and polymers. Coal was also analyzed. It is concluded that the sample preparation step is perhaps the most important part in MALDI. Observed high mass ions in coal may be from contaminant proteins. Optimal matrices must be found. Finally, the mass spectrum is senstive to number average molecular weight; a low value, however, does not preclude presence of high molecular weight species.

  7. Rapid screening of pharmaceutical drugs using thermal desorption - SALDI mass spectrometry

    NASA Astrophysics Data System (ADS)

    Grechnikov, A. A.; Kubasov, A. E.; Georgieva, V. B.; Borodkov, A. S.; Nikiforov, S. M.; Simanovsky, Ya O.; Alimpiev, S. S.

    2012-12-01

    A novel approach to the rapid screening of pharmaceutical drugs by surface assisted laser desorption-ionization (SALDI) mass spectrometry with the rotating ball interface coupled with temperature programmed thermal desorption has been developed. Analytes were thermally desorbed and deposited onto the surface of amorphous silicon substrate attached to the rotating ball. The ball was rotated and the deposited analytes were analyzed using SALDI. The effectiveness of coupling SALDI mass spectrometry with thermal desorption was evaluated by the direct and rapid analysis of tablets containing lidocaine, diphenhydramine and propranolol without any sample pretreatment. The overall duration of the screening procedure was 30÷40 sec. Real urine samples were studied for drug analysis. It is shown that with simple preparation steps, urine samples can be quantitatively analyzed using the proposed technique with the detection limits in the range of 0.2÷0.5 ng/ml.

  8. Laser desorption mass spectrometry for high-throughput DNA analysis and its applications

    NASA Astrophysics Data System (ADS)

    Chen, C. H. Winston; Golovlev, Valeri V.; Taranenko, N. I.; Allman, S. L.; Isola, Narayana R.; Potter, N. T.; Matteson, K. J.; Chang, Linus Y.

    1999-05-01

    Laser desorption mass spectrometry (LDMS) has been developed for DNA sequencing, disease diagnosis, and DNA fingerprinting for forensic applications. With LDMS, the speed of DNA analysis can be much faster than conventional gel electrophoresis. No dye or radioactive tagging to DNA segments for detection is needed. LDMS is emerging as a new alternative technology for DNA analysis.

  9. Laser Desorption Mass Spectrometry for High Throughput DNA Analysis and Its Applications

    SciTech Connect

    Allman, S.L.; Chen, C.H.; Golovlev, V.V.; Isola, N.R.; Matteson, K.J.; Potter, N.T.; Taranenko, N.I.

    1999-01-23

    Laser desorption mass spectrometry (LDMS) has been developed for DNA sequencing, disease diagnosis, and DNA Fingerprinting for forensic applications. With LDMS, the speed of DNA analysis can be much faster than conventional gel electrophoresis. No dye or radioactive tagging to DNA segments for detection is needed. LDMS is emerging as a new alternative technology for DNA analysis.

  10. Identification of Bacteria Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

    ERIC Educational Resources Information Center

    Kedney, Mollie G.; Strunk, Kevin B.; Giaquinto, Lisa M.; Wagner, Jennifer A.; Pollack, Sidney; Patton, Walter A.

    2007-01-01

    Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS or simply MALDI) has become ubiquitous in the identification and analysis of biomacromolecules. As a technique that allows for the molecular weight determination of otherwise nonvolatile molecules, MALDI has had a profound impact in the molecular…

  11. Laser desorption time-of-flight mass spectrometer DNA analyzer. Final report

    SciTech Connect

    Chen, C.H.W.; Martin, S.A.

    1997-02-01

    The objective of this project is the development of a laser desorption time-of-flight mass spectrometer DNA analyzer which can be broadly used for biomedical research. Tasks include: pulsed ion extraction to improve resolution; two-component matrices to enhance ionization; and solid phase DNA purification.

  12. Ambient mass spectrometry imaging: plasma assisted laser desorption ionization mass spectrometry imaging and its applications.

    PubMed

    Feng, Baosheng; Zhang, Jialing; Chang, Cuilan; Li, Liping; Li, Min; Xiong, Xingchuang; Guo, Chengan; Tang, Fei; Bai, Yu; Liu, Huwei

    2014-05-01

    Mass spectrometry imaging (MSI) has been widely used in many research areas for the advantages of providing informative molecular distribution with high specificity. Among the recent progress, ambient MSI has attracted increasing interests owing to its characteristics of ambient, in situ, and nonpretreatment analysis. Here, we are presenting the ambient MSI for traditional Chinese medicines (TCMs) and authentication of work of art and documents using plasma assisted laser desorption ionization mass spectrometry (PALDI-MS). Compared with current ambient MSI methods, an excellent average resolution of 60 μm × 60 μm pixel size was achieved using this system. The feasibility of PALDI-based MSI was confirmed by seal imaging, and its authentication applications were demonstrated by imaging of printed Chinese characters. Imaging of the Radix Scutellariae slice showed that the two active components, baicalein and wogonin, mainly were distributed in the epidermis of the root, which proposed an approach for distinguishing TCMs' origins and the distribution of active components of TCMs and exploring the environmental effects of plant growth. PALDI-MS imaging provides a strong complement for the MSI strategy with the enhanced spatial resolution, which is promising in many research fields, such as artwork identification, TCMs' and botanic research, pharmaceutical applications, etc. PMID:24670045

  13. Laser desorption mass spectrometry: Technical limitations, fundamentals, and application to coal

    SciTech Connect

    Hunt, J.E.; Winans, R.E.

    1995-12-31

    Objective of this study is to assess scope and limitations of laser desorption (LD) and matrix-assisted laser desorption (MALDI) as applied to coals. LD and MALDI mass spectrometry are increasingly used to detect intact molecular species, such as proteins with masses from 1000 to 100,000 amu and beyond. MALDI is also being used for high molecular weight polymers. A good example, related to coal-type systems, is the report on lignin mass spectrometry by MALDI. The mass spectrum shows a wide molecular distribution of several hundred to larger than 16000, with the center of gravity of the distribution around 2600. Results are interpreted in terms of oligomeric lignin molecules. Thus, if there are indeed large molecular species in a polymeric content in coals or coal extracts, MALDI is an attractive technique.

  14. Study of the Thermal Decomposition of Some Components of Biomass by Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Palianytsia, Borys; Kulik, Tetiana; Dudik, Olesia; Cherniavska, Tetiana; Tonkha, Oksana

    The investigation of thermal transformations of lignin samples have been carried out using temperature programmed desorption mass spectrometry method (TPD-MS). Main stages and products of lignin pyrolysis have been identified. The first stages (Tmax = 230 °C and Tmax = 300 °C) are attributed to thermal transformations of lignin peripheral polysaccharide fragments such as hemicellulose and cellulose respectively. The second stage (Tmax = 335 °C) is associated with desorption of lignin structural elements in the molecular forms as a result of depolymerization processes of polymeric blocks of lignin. The third stage (Tmax = 370 °C) correspond to a deeper decomposition of lignin and characterized by desorption of smaller structural fragments in molecular forms (m/z = 110, pyrocatechol). Pressure-temperature curves of pyrolysis of lignin samples have been analyzed.

  15. Graphene matrix for signal enhancement in ambient plasma assisted laser desorption ionization mass spectrometry.

    PubMed

    Chang, Cuilan; Li, Xianjiang; Bai, Yu; Xu, Gege; Feng, Baosheng; Liao, Yiping; Liu, Huwei

    2013-09-30

    In this work, the signal intensity of ambient plasma assisted laser desorption ionization mass spectrometry (PALDI-MS) was significantly increased with graphene as matrix. The graphene functions as a substrate to trap analytes, absorb energy from the visible laser irradiation and transfer energy to the analytes to facilitate the laser desorption process. The desorbed analytes are further ionized by helium plasma and analyzed by MS. Compared with a traditional organic matrix, α-cyano-4-hydroxycinnamic acid (CHCA), graphene exhibited much higher desorption efficiency for most of the compounds benefitting from the strong optical absorption at 532nm. The performance has been confirmed by the facile analysis of more than forty compounds with various structures. Additionally, this method was successfully applied to distinguish three kinds of Chinese tea leaves by detecting the endogenous caffeine and theanine, which proved the utility, facility and convenience of this method for rapid screening of main components in real samples. PMID:23953441

  16. Remote mass spectrometric sampling of electrospray- and desorption electrospray-generated ions using an air ejector.

    PubMed

    Dixon, R Brent; Bereman, Michael S; Muddiman, David C; Hawkridge, Adam M

    2007-10-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data are presented. PMID:17716909

  17. Remote Mass Spectrometric Sampling of Electrospray- and Desorption Electrospray-Generated Ions Using an Air Ejector

    PubMed Central

    Dixon, R. Brent; Bereman, Michael S.; Muddiman, David C.; Hawkridge, Adam M.

    2007-01-01

    A commercial air ejector was coupled to an electrospray ionization linear ion trap mass spectrometer (LTQ) to transport remotely generated ions from both electrospray (ESI) and desorption electrospray ionization (DESI) sources. We demonstrate the remote analysis of a series of analyte ions that range from small molecules and polymers to polypeptides using the AE-LTQ interface. The details of the ESI-AE-LTQ and DESI-AE-LTQ experimental configurations are described and preliminary mass spectrometric data is presented. PMID:17716909

  18. Deblurring molecular images using desorption electrospray ionization mass spectrometry

    PubMed Central

    Parry, R. Mitchell; Galhena, Asiri S.; Fernandez, Facundo M.; Wang, May D.

    2016-01-01

    Traditional imaging techniques for studying the spatial distribution of biological molecules such as proteins, metabolites, and lipids, require the a priori selection of a handful of target molecules. Imaging mass spectrometry provides a means to analyze thousands of molecules at a time within a tissue sample, adding spatial detail to proteomic, metabolomic, and lipidomic studies. Compared to traditional microscopic images, mass spectrometric images have reduced spatial resolution and require a destructive acquisition process. In order to increase spatial detail, we propose a constrained acquisition path and signal degradation model enabling the use of a general image deblurring algorithm. Our analysis shows the potential of this approach and supports prior observations that the effect of the sprayer focuses on a central region much smaller than the extent of the spray. PMID:19963935

  19. Laser desorption fast gas chromatography-mass spectrometry in supersonic molecular beams.

    PubMed

    Shahar, T; Dagan, S; Amirav, A

    1998-06-01

    A novel method for fast analysis is presented. It is based on laser desorption injection followed by fast gas chromatography-mass spectrometry (GC-MS) in supersonic molecular beams. The sample was placed in an open air or purged laser desorption compartment, held at atmospheric pressure and near room temperature conditions. Desorption was performed with a XeCl Excimer pulsed laser with pulse energy of typically 3 mJ on the surface. About 20 pulses at 50 Hz were applied for sample injection, resulting in about 0.4 s injection time and one or a few micrograms sample vapor or small particles. The laser desorbed sample was further thermally vaporized at a heated frit glass filter located at the fast GC inlet. Ultrafast GC separation and quantification was achieved with a 50-cm-long megabore column operated with a high carrier gas flow rate of up to 240 mL/min. The high carrier gas flow rate provided effective and efficient entrainment of the laser desorbed species in the sweeping gas. Following the fast GC separation, the sample was analyzed by mass spectrometry in supersonic molecular beams. Both electron ionization and hyperthermal surface ionization were employed for enhanced selectivity and sensitivity. Typical laser desorption analysis time was under 10 s. The laser desorption fast GC-MS was studied and demonstrated with the following sample/matrices combinations, all without sample preparation or extraction: (a) traces of dioctylphthalate plasticizer oil on stainless steel surface and the efficiency of its cleaning; (b) the detection of methylparathion and aldicarb pesticides on orange leaves; (c) water surface analysis for the presence of methylparathion pesticide; (d) caffeine analysis in regular and decaffeinated coffee powder; (e) paracetamol and codeine drug analysis in pain relieving drug tablets; (f) caffeine trace analysis in raw urine; (g) blood analysis for the presence of 1 ppm lidocaine drug. The features and advantages of the laser desorption fast GC

  20. Determining fatty acids by desorption/ionization mass spectrometry using thin-layer chromatography substrates.

    PubMed

    Mirabelli, Mario F; Coviello, Giuseppe; Volmer, Dietrich A

    2015-06-01

    In this study, we demonstrate the application of ambient mass spectrometry for measuring fatty acids from various biological sample matrices such as olive oil, fish oil, salmon, and human serum. Optimum performance was obtained after spotting samples onto thin-layer chromatography (TLC) plates as sample substrates for a custom-built solvent-assisted desorption/ionization mass spectrometry (DI-MS) interface. Good to excellent linearities (coefficients of determination, 0.9856 to 0.9977) and reproducibilities (average 6 % relative standard deviation (RSD) using syringe deposition) were obtained after application of an internal standard. Signal suppression phenomena were minimized by separating the analytes by TLC to some extent prior to DI-MS, leading to a fourfold increase of signal-to-noise ratios as compared to single spot mixture analysis without TLC separation. Graphical Abstract Solvent-assisted desorption/ionization-mass spectrometry. PMID:25814272

  1. Matrix-assisted laser desorption fourier transform mass spectrometry for biological compounds

    SciTech Connect

    Hettich, R.; Buchanan, M.

    1990-01-01

    The recent development of matrix-assisted UV laser desorption (LD) mass spectrometry has made possible the ionization and detection of extremely large molecules (with molecular weights exceeding 100,000 Daltons). This technique has generated enormous interest in the biological community for the direct examination of large peptides and oligonucleotides. Although this matrix-assisted ionization method has been developed and used almost exclusively with time-of-flight (TOF) mass spectrometers, research is currently in progress to demonstrate this technique with trapped ion mass spectrometers, such as Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The potential capabilities of FTMS for wide mass range, high resolution measurement, and ion trapping experiments suggest that this instrumental technique should be useful for the detailed structural characterization of large ions generated by the matrix-assisted technique. We have recently demonstrated that matrix-assisted ultraviolet laser desorption can be successfully used with FTMS for the ionization of small peptides. The objective of this report is to summarize the application and current limitations of matrix-assisted laser desorption FTMS for the characterization of peptides and oligonucleotides at the isomeric level. 4 refs., 3 figs., 2 tabs.

  2. Ambient diode laser desorption dielectric barrier discharge ionization mass spectrometry of nonvolatile chemicals.

    PubMed

    Gilbert-López, Bienvenida; Schilling, Michael; Ahlmann, Norman; Michels, Antje; Hayen, Heiko; Molina-Díaz, Antonio; García-Reyes, Juan F; Franzke, Joachim

    2013-03-19

    In this work, the combined use of desorption by a continuous wave near-infrared diode laser and ionization by a dielectric barrier discharge-based probe (laser desorption dielectric barrier discharge ionization mass spectrometry (LD-DBDI-MS)) is presented as an ambient ionization method for the mass spectrometric detection of nonvolatile chemicals on surfaces. A separation of desorption and ionization processes could be verified. The use of the diode laser is motivated by its low cost, ease of use, and small size. To achieve an efficient desorption, the glass substrates are coated at the back side with a black point (target point, where the sample is deposited) in order to absorb the energy offered by the diode laser radiation. Subsequent ionization is accomplished by a helium plasmajet generated in the dielectric barrier discharge source. Examples on the application of this approach are shown in both positive and negative ionization modes. A wide variety of multiclass species with low vapor pressure were tested including pesticides, pharmaceuticals and explosives (reserpine, roxithromycin, propazine, prochloraz, spinosad, ampicillin, dicloxacillin, enrofloxacin, tetracycline, oxytetracycline, erythromycin, spinosad, cyclo-1,3,5,7-tetramethylene tetranitrate (HMX), and cyclo-1,3,5-trimethylene trinitramine (RDX)). A comparative evaluation revealed that the use of the laser is advantageous, compared to just heating the substrate surface. PMID:23419061

  3. Note: A versatile mass spectrometer chamber for molecular beam and temperature programmed desorption experiments

    NASA Astrophysics Data System (ADS)

    Tonks, James P.; Galloway, Ewan C.; King, Martin O.; Kerherve, Gwilherm; Watts, John F.

    2016-08-01

    A dual purpose mass spectrometer chamber capable of performing molecular beam scattering (MBS) and temperature programmed desorption (TPD) is detailed. Two simple features of this design allow it to perform these techniques. First, the diameter of entrance aperture to the mass spectrometer can be varied to maximize signal for TPD or to maximize angular resolution for MBS. Second, the mass spectrometer chamber can be radially translated so that it can be positioned close to the sample to maximize signal or far from the sample to maximize angular resolution. The performance of this system is described and compares well with systems designed for only one of these techniques.

  4. Note: A versatile mass spectrometer chamber for molecular beam and temperature programmed desorption experiments.

    PubMed

    Tonks, James P; Galloway, Ewan C; King, Martin O; Kerherve, Gwilherm; Watts, John F

    2016-08-01

    A dual purpose mass spectrometer chamber capable of performing molecular beam scattering (MBS) and temperature programmed desorption (TPD) is detailed. Two simple features of this design allow it to perform these techniques. First, the diameter of entrance aperture to the mass spectrometer can be varied to maximize signal for TPD or to maximize angular resolution for MBS. Second, the mass spectrometer chamber can be radially translated so that it can be positioned close to the sample to maximize signal or far from the sample to maximize angular resolution. The performance of this system is described and compares well with systems designed for only one of these techniques. PMID:27587173

  5. Identification of fleeting electrochemical reaction intermediates using desorption electrospray ionization mass spectrometry.

    PubMed

    Brown, Timothy A; Chen, Hao; Zare, Richard N

    2015-06-17

    We report a new method for the mass spectrometric detection of fleeting reaction intermediates in electrochemical reactions utilizing a "waterwheel" working electrode setup. This setup takes inspiration from desorption electrospray ionization (DESI) mass spectrometry, where the sampling time is on the order of milliseconds, to sample directly from the surface of a working electrode for mass spectrometric analysis. We present data that show the formation of a diimine intermediate of the electrochemical oxidation of uric acid that has a lifetime in solution of 23 ms as well as data that provide evidence for the formation of a similar diimine species from the electrooxidation of xanthine, which has not been previously observed. PMID:26030136

  6. Recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry.

    PubMed

    Wang, Jing; Liu, Qian; Liang, Yong; Jiang, Guibin

    2016-04-01

    Carbon nanomaterials have attracted great interest over past decades owing to their unique physical properties, versatile functionalization chemistry, and biological compatibility. In this article, we review recent progress in application of carbon nanomaterials in laser desorption/ionization mass spectrometry (LDI MS). Various types of carbon nanomaterials, including fullerenes, carbon nanotubes, graphene, carbon nanodots, nanodiamond, nanofibers, nanohorns, and their derivative forms, are involved. The applications of these materials as new matrices or probes in matrix-assisted or surface-enhanced laser desorption/ionization mass spectrometry (MALDI or SELDI MS) are discussed. Finally, we summarize current challenges and give our perspectives on the future of applications of carbon nanomaterials in LDI MS. Graphical Abstract Carbon nanomaterials (e.g., fullerenes, carbon nanotubes, graphene, nanodiamond, etc.) can be used as novel matrices or probes in MALDI or SELDI MS. PMID:26753968

  7. Comparison of Three Plasma Sources for Ambient Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    McKay, Kirsty; Salter, Tara L.; Bowfield, Andrew; Walsh, James L.; Gilmore, Ian S.; Bradley, James W.

    2014-09-01

    Plasma-based desorption/ionization sources are an important ionization technique for ambient surface analysis mass spectrometry. In this paper, we compare and contrast three competing plasma based desorption/ionization sources: a radio-frequency (rf) plasma needle, a dielectric barrier plasma jet, and a low-temperature plasma probe. The ambient composition of the three sources and their effectiveness at analyzing a range of pharmaceuticals and polymers were assessed. Results show that the background mass spectrum of each source was dominated by air species, with the rf needle producing a richer ion spectrum consisting mainly of ionized water clusters. It was also seen that each source produced different ion fragments of the analytes under investigation: this is thought to be due to different substrate heating, different ion transport mechanisms, and different electric field orientations. The rf needle was found to fragment the analytes least and as a result it was able to detect larger polymer ions than the other sources.

  8. Role of the support material on laser desorption/ionization mass spectra.

    PubMed

    Gruszecka, A; Szymanska-Chargot, M; Smolira, A; Cytawa, J; Michalak, L

    2008-04-01

    We report the results of experimental studies on the effects of sample supports in laser desorption/ionization mass spectrometry (LDI-MS). LDI time-of-flight (TOF) mass spectra obtained for C(60) and insulin samples deposited onto standard stainless steel substrate and/or onto some non-metallic materials (glass, scotch tape, floppy disc foil, Teflon foil, photocopy film), all recorded under identical, typical experimental conditions, have been compared with regard to their intensity and quality. The LDI investigations show that compared with stainless steel, glass and floppy disc foil sample supports boost (2-3.5 times) ion yields for C(60)(+) and C(60)(-) ions, respectively. The stainless steel and scotch tape sample supports are the best for the mass resolution of positive ions and the formation of (C(60))(n)(-) (n desorption/ionization (MALDI) we did not observe significant differences in sensitivity for the support materials tested. A mechanism of ion formation in the desorption plume is suggested. PMID:18302166

  9. Thin-Layer Chromatography/Desorption Electrospray Ionization Mass Spectrometry: Investigation of Goldenseal Alkaloids

    SciTech Connect

    Van Berkel, Gary J; Tomkins, Bruce A; Kertesz, Vilmos

    2007-01-01

    Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cm x 10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed RF value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile proving superior to methanol. The detection levels (ca. 5 ng each or 14 -28 pmol) in mass spectral full scan mode were determined statistically from the calibration curves (2.5 - 100 pmol) for the standards berberine, palmatine and hydrastinine spotted as a mixture and separated on the plates. Qualitative screening of the major alkaloids present in six different over-the-counter "goldenseal" dietary supplements was accomplished by obtaining full scan mass spectra during surface scans along the development lane in the direction of increasing RF value. In one sample, alkaloids were detected that strongly suggested the presence of at least one additional herb undeclared on the product label. These same data indicated the misidentification of one of the alkaloids in the TLC literature. Quantities of the alkaloids present in two of the samples determined using the mass spectral data were in reasonable agreement with the label values indicating the quantitative ability of

  10. The Application of Ultrafast Laser Pulses to Laser Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Cui, Yang

    Ultrashort femtosecond laser pulses display exceptional performance for the selective ablation of materials, includes metals, semiconductors, and biological tissues. They do not damage the remaining unablated portion of a sample, which permits the possibility of depth profiling by repeat sampling at the same location. With sufficiently micro-focused fs laser pulse length beam, high lateral resolution mass spectrometry imaging is possible, while sample damage may degrade ultimate lateral resolution in some other methods. Combining imaging and depth profiling could ultimately leads to tomographical mass spectrometry or 3D imaging MS. Laser postionization, a "soft" ionization method, was combined with ultrafast laser desorption for enhanced molecular analysis. A customized femtosecond laser desorption/ablation postionization time-of-flight mass spectrometer was designed and built. The construction and performance of both phases including the VUV source are detailed. Instrument control software was written to operate this instrument, and many automated experiments were successfully demonstrated by this software. Elemental and molecular analysis was carried out on the instrument and demonstrated exceptional performance for fs laser pulse sampling of small areas. Studies demonstrated the imaging and depth profiling capability of fs-LDPI on metals, semiconductors and intact biofilm tissues. Attempts were made to reach the limit of lateral resolution of imaging by fs-LDPI-MS. The results showed similar lateral resolution of <2 mum for both fs 800 nm and 400 nm desorption beams. To improve the repetition rate for high speed imaging application, an alternative LDPI scheme was designed and constructed. The fs 800 beam was tripled to 267 nm and delivered into the ion source as an ionization laser, while a ns 349 nm pulse laser was used for desorption. Preliminary data showed certain intact molecular ions can be detected. Fragmentation tendency was measured against various

  11. Laser desorption/ionization mass spectrometry on nanostructured semiconductor substrates: DIOS(TM) and QuickMass(TM)

    NASA Astrophysics Data System (ADS)

    Law, K. P.

    2010-02-01

    In the era of systems biology, new analytical platforms are under demand. Desorption/ionization on silicon mass spectrometry (DIOS-MS) is a promising high throughput laser mass spectrometry approach that has attracted a lot of attention, and has been commercialized. Another substrate material manufactured by physical method has also been made commercially available under the trade name of QuickMass(TM). These two commercial substrates, DIOS(TM) and QuickMass(TM), were investigated independently from the manufacturers and were characterized by a number of advanced surface techniques. This work determined (1) the correlation between the substrate physicochemical properties and their LDI activity, (2) the feasibility of metabolic profiling from complex biological matrices and (3) the laser desorption/ionization mechanism. The DIOS(TM) substrate was characterized with a thick nano-sized porous layer, a high surface concentration of fluorocarbon and silicon oxides and super-hydrophobicity. In contrast, the QuickMass(TM) substrate consisted of a non-porous germanium thin-film. The relatively high ionization efficiency obtained from the DIOS(TM) substrate was contributed to the fluorosilane manufacturing processes and its porous morphology. Despite the QuickMass(TM) substrate being less effective, it was noted that the use of germanium affords a self-cleaning mechanism and suppresses background interference of mass spectra. The suitability of DIOS(TM) substrates for metabolic profiling of complex biological matrices was demonstrated. DIOS mass spectra of human blood plasma, human urine and animal liver tissue extracts were produced. Suitable extraction methods were found to be important, but relatively simplified approaches were sufficient. Further investigations of the DIOS desorption/ionization mechanism were carried out. The previously proposed sub-surface state reaction could be a molten-solid interfacial state reaction of the substrate and this had a significant

  12. Molecular Weight Determinations of Proteins by Californium Plasma Desorption Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Sundqvist, B.; Roepstorff, Peter; Fohlman, J.; Hedin, A.; Hakansson, P.; Kamensky, I.; Lindberg, M.; Salehpour, M.; Sawe, G.

    1984-11-01

    The plasma desorption mass spectrometry method is used to determine the molecular weights of larger molecules than before, to determine the molecular weights of proteins and peptides in mixtures, and to monitor protein modification reactions. Proteins up to molecular weight 25,000 can now be studied with a mass spectrometric technique. Protein-peptide mixtures that could not be resolved with conventional techniques were successfully analyzed by this technique. The precision of the method is good enough to permit one to follow the different steps in the conversion of porcine insulin to human insulin.

  13. Forensic applications of desorption electrospray ionisation mass spectrometry (DESI-MS).

    PubMed

    Morelato, Marie; Beavis, Alison; Kirkbride, Paul; Roux, Claude

    2013-03-10

    Desorption electrospray ionisation mass spectrometry (DESI-MS) is an emerging analytical technique that enables in situ mass spectrometric analysis of specimens under ambient conditions. It has been successfully applied to a large range of forensically relevant materials. This review assesses and highlights forensic applications of DESI-MS including the analysis and detection of illicit drugs, explosives, chemical warfare agents, inks and documents, fingermarks, gunshot residues and drugs of abuse in urine and plasma specimens. The minimal specimen preparation required for analysis and the sensitivity of detection achieved offer great advantages, especially in the field of forensic science. PMID:23498998

  14. The Need for Speed in Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry

    PubMed Central

    Prentice, Boone M.; Caprioli, Richard M.

    2016-01-01

    Imaging mass spectrometry (IMS) has emerged as a powerful analytical tool enabling the direct molecular mapping of many types of tissue. Specifically, matrix-assisted laser desorption/ ionization (MALDI) represents one of the most broadly applicable IMS technologies. In recent years, advances in solid state laser technology, mass spectrometry instrumentation, computer technology, and experimental methodology have produced IMS systems capable of unprecedented data acquisition speeds (>50 pixels/second). In applications of this technology, throughput is an important consideration when designing an IMS experiment. As IMS becomes more widely adopted, continual improvements in experimental setups will be important to address biologically and clinically relevant time scales.

  15. Brominated Tyrosine and Polyelectrolyte Multilayer Analysis by Laser Desorption VUV Postionization and Secondary Ion Mass Spectrometry

    PubMed Central

    Melvin Blaze, M.T.; Takahashi, Lynelle K.; Zhou, Jia; Ahmed, Musahid; Gasper, Gerald L.; Pleticha, F. Douglas; Hanley, Luke

    2011-01-01

    The small molecular analyte 3,5-dibromotyrosine (Br2Y) and chitosan-alginate polyelectrolyte multilayers (PEM) with and without adsorbed Br2Y were analyzed by laser desorption postionization mass spectrometry (LDPI-MS). LDPI-MS using 7.87 eV laser and tunable 8 – 12.5 eV synchrotron vacuum ultraviolet (VUV) radiation found that desorption of clusters from Br2Y films allowed detection by ≤8 eV single photon ionization. Thermal desorption and electronic structure calculations determined the ionization energy of Br2Y to be ~8.3±0.1 eV and further indicated that the lower ionization energies of clusters permitted their detection at ≤8 eV photon energies. However, single photon ionization could only detect Br2Y adsorbed within PEMs when using either higher photon energies or matrix addition to the sample. All samples were also analyzed by 25 keV Bi3+ secondary ion mass spectrometry (SIMS), with the negative ion spectra showing strong parent ion signal which complemented that observed by LDPI-MS. However, the negative ion SIMS appeared strongly dependent on the high electron affinity of this specific analyte and the analyte’s condensed phase environment. PMID:21548612

  16. Laser Desorption Ionization Mass Spectrometry Imaging of Drosophila Brain Using Matrix Sublimation versus Modification with Nanoparticles.

    PubMed

    Phan, Nhu T N; Mohammadi, Amir Saeid; Dowlatshahi Pour, Masoumeh; Ewing, Andrew G

    2016-02-01

    Laser desorption ionization mass spectrometry (LDI-MS) is used to image brain lipids in the fruit fly, Drosophila, a common invertebrate model organism in biological and neurological studies. Three different sample preparation methods, including sublimation with two common organic matrixes for matrix-assisted laser desorption ionization (MALDI) and surface-assisted laser desorption ionization (SALDI) using gold nanoparticles, are examined for sample profiling and imaging the fly brain. Recrystallization with trifluoroacetic acid following matrix deposition in MALDI is shown to increase the incorporation of biomolecules with one matrix, resulting in more efficient ionization, but not for the other matrix. The key finding here is that the mass fragments observed for the fly brain slices with different surface modifications are significantly different. Thus, these approaches can be combined to provide complementary analysis of chemical composition, particularly for the small metabolites, diacylglycerides, phosphatidylcholines, and triacylglycerides, in the fly brain. Furthermore, imaging appears to be beneficial using modification with gold nanoparticles in place of matrix in this application showing its potential for cellular and subcellular imaging. The imaging protocol developed here with both MALDI and SALDI provides the best and most diverse lipid chemical images of the fly brain to date with LDI. PMID:26705612

  17. Pyroelectricity Assisted Infrared-Laser Desorption Ionization (PAI-LDI) for Atmospheric Pressure Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Li, Yanyan; Ma, Xiaoxiao; Wei, Zhenwei; Gong, Xiaoyun; Yang, Chengdui; Zhang, Sichun; Zhang, Xinrong

    2015-08-01

    A new atmospheric pressure ionization method termed pyroelectricity-assisted infrared laser desorption ionization (PAI-LDI) was developed in this study. The pyroelectric material served as both sample target plate and enhancing ionization substrate, and an IR laser with wavelength of 1064 nm was employed to realize direct desorption and ionization of the analytes. The mass spectra of various compounds obtained on pyroelectric material were compared with those of other substrates. For the five standard substances tested in this work, LiNbO3 substrate produced the highest ion yield and the signal intensity was about 10 times higher than that when copper was used as substrate. For 1-adamantylamine, as low as 20 pg (132.2 fmol) was successfully detected. The active ingredient in (Compound Paracetamol and 1-Adamantylamine Hydrochloride Capsules), 1-adamantylamine, can be sensitively detected at an amount as low as 150 pg, when the medicine stock solution was diluted with urine. Monosaccharide and oligosaccharides in Allium Cepa L. juice was also successfully identified with PAI-LDI. The method did not require matrix-assisted external high voltage or other extra facility-assisted set-ups for desorption/ionization. This study suggested exciting application prospect of pyroelectric materials in matrix- and electricity-free atmospheric pressure mass spectrometry research.

  18. Brominated Tyrosine and Polyelectrolyte Multilayer Analysis by Laser Desorption VUV Postionization and Secondary Ion Mass Spectrometry

    SciTech Connect

    University of Illinois at Chicago; Blaze, Melvin M. T.; Takahashi, Lynelle; Zhou, Jia; Ahmed, Musahid; Gasper, Gerald; Pleticha, F. Douglas; Hanley, Luke

    2011-03-14

    The small molecular analyte 3,5-dibromotyrosine (Br2Y) and chitosan-alginate polyelectrolyte multilayers (PEM) with and without adsorbed Br2Y were analyzed by laser desorption postionization mass spectrometry (LDPI-MS). LDPI-MS using 7.87 eV laser and tunable 8 ? 12.5 eV synchrotron vacuum ultraviolet (VUV) radiation found that desorption of clusters from Br2Y films allowed detection by≤8 eV single photon ionization. Thermal desorption and electronic structure calculations determined the ionization energy of Br2Y to be ~;;8.3?0.1 eV and further indicated that the lower ionization energies of clusters permitted their detection at≤8 eV photon energies. However, single photon ionization could only detect Br2Y adsorbed within PEMs when using either higher photon energies or matrix addition to the sample. All samples were also analyzed by 25 keV Bi3 + secondary ion mass spectrometry (SIMS), with the negative ion spectra showing strong parent ion signal which complemented that observed by LDPI-MS. The negative ion SIMS depended strongly on the high electron affinity of this specific analyte and the analyte?s condensed phase environment.

  19. Fast Differential Analysis of Propolis Using Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

    PubMed Central

    Huang, Xue-yong; Guo, Xia-li; Luo, Huo-lin; Fang, Xiao-wei; Zhu, Teng-gao; Zhang, Xing-lei; Chen, Huan-wen; Luo, Li-ping

    2015-01-01

    Mass spectral fingerprints of 24 raw propolis samples, including 23 from China and one from the United States, were directly obtained using surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) without sample pretreatment. Under the optimized experimental conditions, the most abundant signals were detected in the mass ranges of 70 to 500 m/z and 200 to 350 m/z, respectively. Principal component analyses (PCA) for the two mass ranges showed similarities in that the colors had a significant correlation with the first two PCs; in contrast there was no correlation with the climatic zones from which the samples originated. Analytes such as chrysin, pinocembrin, and quercetin were detected and identified using multiple stage mass spectrometry within 3 min. Therefore, SDAPCI-MS can be used for rapid and reliable high-throughput analysis of propolis. PMID:26339245

  20. Development of Laser Desorption Imaging Mass Spectrometry Methods to Investigate the Molecular Composition of Latent Fingermarks

    NASA Astrophysics Data System (ADS)

    Lauzon, Nidia; Dufresne, Martin; Chauhan, Vinita; Chaurand, Pierre

    2015-06-01

    For a century, fingermark analysis has been one of the most important and common methods in forensic investigations. Modern chemical analysis technologies have added the potential to determine the molecular composition of fingermarks and possibly identify chemicals a suspect may have come into contact with. Improvements in analytical detection of the molecular composition of fingermarks is therefore of great importance. In this regard, matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) imaging mass spectrometry (IMS) have proven to be useful technologies for fingermark analysis. In these analyses, the choice of ionizing agent and its mode of deposition are critical steps for the identification of molecular markers. Here we propose two novel and complementary IMS approaches for endogenous and exogenous substance detection in fingermarks: sublimation of 2-mercaptobenzothiazol (2-MBT) matrix and silver sputtering.

  1. Silica-fiber microextraction for laser desorption ion trap mass spectrometry

    SciTech Connect

    Cisper, M.E.; Earl, W.L.; Nogar, N.S.; Hemberger, P.H. )

    1994-06-01

    We have coupled sample collection by solid-phase microextraction on disposable fused silica optical fibers with analysis by laser desorption ion trap mass spectrometry for rapid screening of organic contaminants in complex matrices. Because the silica-fiber probe serves as both the sampling medium and the sample support for laser desorption, traditional methods of sample preparation are eliminated with the expected gains in speed and simplicity. Pyrene was the benchmark compound in these experiments but we show that the technique is also applicable to other polycyclic aromatic hydrocarbons (PAHs) and semivolatile compounds, laser dyes, pesticides, and peptides. Derivatizing the silica fiber improves the analyte collection efficiency, and firing the laser during a ring electrode rf ramp promotes dependable trapping of laser-desorbed ions. 32 refs., 5 figs.

  2. Development of laser desorption imaging mass spectrometry methods to investigate the molecular composition of latent fingermarks.

    PubMed

    Lauzon, Nidia; Dufresne, Martin; Chauhan, Vinita; Chaurand, Pierre

    2015-06-01

    For a century, fingermark analysis has been one of the most important and common methods in forensic investigations. Modern chemical analysis technologies have added the potential to determine the molecular composition of fingermarks and possibly identify chemicals a suspect may have come into contact with. Improvements in analytical detection of the molecular composition of fingermarks is therefore of great importance. In this regard, matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) imaging mass spectrometry (IMS) have proven to be useful technologies for fingermark analysis. In these analyses, the choice of ionizing agent and its mode of deposition are critical steps for the identification of molecular markers. Here we propose two novel and complementary IMS approaches for endogenous and exogenous substance detection in fingermarks: sublimation of 2-mercaptobenzothiazol (2-MBT) matrix and silver sputtering. PMID:25846823

  3. Nanospray Desorption Electrospray Ionization: an Ambient Method for Liquid-Extraction Surface Sampling in Mass Spectrometry

    SciTech Connect

    Roach, Patrick J.; Laskin, Julia; Laskin, Alexander

    2010-08-17

    A novel nanospray desorption electrospray ionization (nano-DESI) approach is presented and its analytical applications are demonstrated for trace analysis of complex organic analytes deposited on substrates. In this approach the analyte is probed by a micro-droplet of charged solvent formed at the junction between two capillaries. One primary capillary is used to create and maintain a charged micro-droplet of solvent on the substrate while a second capillary is used to create a self-aspirating nanospray that delivers solvent dissolved analyte to the inlet of a mass spectrometer. This approach enables efficient separation of desorption and ionization events, thus providing better control over transport and ionization of the analyte. In this letter we present the basics of the nano-DESI approach and demonstrate its analytical capabilities. Specifically, we demonstrate significant improvement of the limits of detection and the stability of the signal as compared to the traditional DESI and discuss imaging applications.

  4. Infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging analysis of biospecimens.

    PubMed

    Bokhart, M T; Muddiman, D C

    2016-09-21

    Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) is a technique well suited for analysis of biological specimens. This tutorial review focuses on recent advancements and applications of IR-MALDESI MSI to better understand key biological questions. Through optimization of user-defined source parameters, comprehensive and quantitative MSI data can be obtained for a variety of analytes. The effect of an ice matrix layer is well defined in the context of desorption dynamics and resulting ion abundance. Optimized parameters and careful control of conditions affords quantitative MSI data which provides valuable information for targeted, label-free drug distribution studies and untargeted metabolomic datasets. Challenges and limitations of MSI using IR-MALDESI are addressed in the context of the bioimaging field. PMID:27484166

  5. Ambient Femtosecond Laser Vaporization and Nanosecond Laser Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Flanigan, Paul; Levis, Robert

    2014-06-01

    Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of <100 fs to enable matrix-free laser vaporization with little or no fragmentation. When coupled to electrospray ionization, femtosecond laser vaporization provides a universal, rapid mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 1013 W cm-2 desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.

  6. High-resolution atmospheric pressure infrared laser desorption/ionization mass spectrometry imaging of biological tissue.

    PubMed

    Römpp, Andreas; Schäfer, Karl Christian; Guenther, Sabine; Wang, Zheng; Köstler, Martin; Leisner, Arne; Paschke, Carmen; Schramm, Thorsten; Spengler, Bernhard

    2013-09-01

    An atmospheric pressure laser desorption/ionization mass spectrometry imaging ion source has been developed that combines high spatial resolution and high mass resolution for the in situ analysis of biological tissue. The system is based on an infrared laser system working at 2.94 to 3.10 μm wavelength, employing a Nd:YAG laser-pumped optical parametrical oscillator. A Raman-shifted Nd:YAG laser system was also tested as an alternative irradiation source. A dedicated optical setup was used to focus the laser beam, coaxially with the ion optical axis and normal to the sample surface, to a spot size of 30 μm in diameter. No additional matrix was needed for laser desorption/ionization. A cooling stage was developed to reduce evaporation of physiological cell water. Ions were formed under atmospheric pressure and transferred by an extended heated capillary into the atmospheric pressure inlet of an orbital trapping mass spectrometer. Various phospholipid compounds were detected, identified, and imaged at a pixel resolution of up to 25 μm from mouse brain tissue sections. Mass accuracies of better than 2 ppm and a mass resolution of 30,000 at m/z = 400 were achieved for these measurements. PMID:23877173

  7. A new method for analysis of reactive adsorbed intermediates: Bismuth postdosing in thermal desorption mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Campbell, Charles T.; Rodriguez, J. A.; Henn, F. C.; Campbell, J. M.; Dalton, P. J.; Seimanides, S. G.

    1988-05-01

    A new method which should have relatively general applicability for the identification and quantitative analysis of reactive adsorbed molecular intermediates in surface reactions will be described, and the first examples of its application will be presented. When a reactive intermediate is generated on a surface, it often has a tendency to dissociate before desorbing. Since dissociation generally requires additional free sites on the surface, dissociation can be suppressed and desorption correspondingly enhanced if the free sites on the surface can be properly poisoned. We have found that bismuth adatoms are very good inert site blockers, which can be postdosed to the surface of a transition metal containing a reactive adsorbed hydrocarbon without destroying the hydrocarbon. Whereas in the absence of bismuth, the hydrocarbon would completely dehydrogenate during thermal desorption spectroscopy (TDS) and liberate only H2 into the gas phase, after bismuth postdosing the reactive hydrocarbon desorbs intact for mass spectral identification and quantitative analysis. This method has been used to prove that adsorbed benzene is the initial product of the dehydrogenation of cyclohexane on Pt(111) at ˜235 K. In the absence of bismuth, this benzene all dissociates during TDS to liberate only H2, leaving graphitic carbon residue on the surface. When one-third monolayer of Bi is postdosed at 110 K, the dehydrogenation pathway is sterically poisoned and the adsorbed benzene quantitatively desorbs during TDS, where it is unambiguously identified by mass spectroscopy. By briefly heating the reactive adsorbed intermediate to increasing temperatures prior to Bi deposition, the thermal stability limits of the intermediate and the kinetic parameters for its dissociation can be established. This is demonstrated for the dehydrogenation reaction of adsorbed cyclopentene on Pt(111). Bismuth postdosing in thermal desorption mass spectroscopy (BPTDS) should be a very useful but

  8. Analysis of sexual assault evidence by desorption electrospray ionization mass spectrometry.

    PubMed

    Mirabelli, Mario F; Chramow, Alexander; Cabral, Elaine C; Ifa, Demian R

    2013-07-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) is employed in the forensic analysis of chemical components present in condoms and imaging of latent fingerprints as circumstantial evidence of sexual assault. Polymers such as nonoxynol-9, polyethylene glycol, and polydimethylsiloxane, as well as small molecules additives such as N-methylmorpholine, N-octylamine, N,N-dibutyl formamide, and isonox 132, commonly used in lubricated condom formulations, were successfully characterized by DESI. The results suggest that DESI-MS is useful for identification of this type of evidence, and it has advantages over conventional extractive techniques, in terms of speed of analysis and ease of use. PMID:23832933

  9. Desorption Electrospray Ionization Mass Spectrometry for Lipid Characterization and Biological Tissue Imaging

    PubMed Central

    Eberlin, Livia S.; Ferreira, Christina R.; Dill, Allison L.; Ifa, Demian R.; Cooks, R. Graham

    2011-01-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) imaging of biological samples allows untargeted analysis and structural characterization of lipids ionized from the near-surface region of a sample under ambient conditions. DESI is a powerful and sensitive MS ionization method for 2D and 3D imaging of lipids from direct and unmodified complex biological samples. This review describes the strengths and limitations of DESI-MS for lipid characterization and imaging together with the technical workflow and a survey of applications. Included are discussions of lipid mapping and biomarker discovery as well as a perspective on the future of DESI imaging. PMID:21645635

  10. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    SciTech Connect

    Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F; Hanley, Luke

    2010-08-04

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.

  11. Laser desorption/ionization mass spectrometry of lipids using etched silver substrates.

    PubMed

    Schnapp, Andreas; Niehoff, Ann-Christin; Koch, Annika; Dreisewerd, Klaus

    2016-07-15

    Silver-assisted laser desorption/ionization mass spectrometry can be used for the analysis of small molecules. For example, adduct formation with silver cations enables the molecular analysis of long-chain hydrocarbons, which are difficult to ionize via conventional matrix-assisted laser desorption ionization (MALDI). Here we used highly porous silver foils, produced by etching with nitric acid, as sample substrates for LDI mass spectrometry. As model system for the analysis of complex lipid mixtures, cuticular extracts of fruit flies (Drosophila melanogaster) and worker bees (Apis mellifera) were investigated. The mass spectra obtained by spotting extract onto the etched silver substrates demonstrate the sensitive detection of numerous lipid classes such as long-chain saturated and unsaturated hydrocarbons, fatty acyl alcohols, wax esters, and triacylglycerols. MS imaging of cuticular surfaces with a lateral resolution of a few tens of micrometers became possible after blotting, i.e., after transferring lipids by physical contact with the substrate. The examples of pheromone-producing male hindwings of the squinting bush brown butterfly (Bicyclus anynana) and a fingermark are shown. Because the substrates are also easy to produce, they provide a viable alternative to colloidal silver nanoparticles and other so far described silver substrates. PMID:26827933

  12. Imaging of Proteins in Tissue Samples Using Nanospray Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Hsu, Cheng-Chih; Chou, Pi-Tai; Zare, Richard N

    2015-11-17

    Chemical maps of tissue samples provide important information on biological processes therein. Recently, advances in tissue imaging have been achieved using ambient ionization techniques, such as desorption electrospray ionization mass spectrometry (DESI-MS), but such techniques have been almost exclusively confined to the mapping of lipids and metabolites. We report here the use of nanospray desorption electrospray ionization (nanoDESI) that allows us to image proteins in tissue samples in a label-free manner at atmospheric pressure with only minimum sample preparation. Multiply charged proteins with masses up to 15 kDa were successfully detected by nanoDESI using an LTQ Orbitrap mass spectrometer. In an adult mice brain section, expression of proteins including ubiquitin, β-thymosin, myelin basic protein, and hemoglobin were spatially mapped and characterized. We also determined the location of methylation on myelin basic protein. This imaging modality was further implemented to MYC-induced lymphomas. We observed an array of truncated proteins in the region where normal thymus cells were infiltrated by tumor cells, in contrast to healthy tissue. PMID:26509582

  13. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    PubMed Central

    Gasper, Gerald L.; Takahashi, Lynelle K.; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F.; Hanley, Luke

    2010-01-01

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 – 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics and extracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms. PMID:20712373

  14. Removal of mercury contamination on primary mass standards by hydrogen plasma and thermal desorption

    NASA Astrophysics Data System (ADS)

    Fuchs, P.; Marti, K.; Russi, S.

    2013-02-01

    The removal of a high mercury contamination on a Pt reference mass by thermal desorption was studied directly by x-ray photoemission spectroscopy (XPS). Subsequently the contamination mechanism was investigated. Samples of PtIr and AuPt exposed to vapour of mercury in air were studied using XPS and gravimetric mass determination. We find an extremely rapid mercury contamination which takes place within minutes and reaches an initial equilibrium state after 2 h to 4 h. Roughly 1 to 2 monolayers of mercury adsorbs directly on the metal surface. A natural contamination of carbon and oxygen compounds is at the top. Due to the accumulation of mercury, we find a gain in mass which corresponds to 20 µg to 26 µg for a PtIr standard. XPS data from a historical Pt standard give strong evidence for further average mercury accumulation of (1.3 ± 0.1) µg/year during a period of more than a century. This can be explained by a two-step mechanism presented in this study. The speed of contamination depends on the initial surface conditions. Polishing activates the surface and results in an enhanced accumulation of mercury. Natural contamination by C and O can delay but not prevent contamination. We further demonstrate that the mercury contamination can be removed by both hydrogen plasma and thermal desorption. The removal of mercury by hydrogen plasma can directly be attributed to the synthesis of gaseous mercury dihydrides at low pressures.

  15. Identification of Microalgae by Laser Desorption/Ionization Mass Spectrometry Coupled with Multiple Nanomatrices.

    PubMed

    Peng, Lung-Hsiang; Unnikrishnan, Binesh; Shih, Chi-Yu; Hsiung, Tung-Ming; Chang, Jeng; Hsu, Pang-Hung; Chiu, Tai-Chia; Huang, Chih-Ching

    2016-04-01

    In this study, we demonstrate a simple method to identify microalgae by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using three different substrates: HgSe, HgTe, and HgTeSe nanostructures. The fragmentation/ionization processes of complex molecules in algae varied according to the heat absorption and transfer efficiency of the nanostructured matrices (NMs). Therefore, the mass spectra obtained for microalgae showed different patterns of m/z values for different NMs. The spectra contained both significant and nonsignificant peaks. Constructing a Venn diagram with the significant peaks obtained for algae when using HgSe, HgTe, and HgTeSe NMs in m/z ratio range 100-1000, a unique relationship among the three sets of values was obtained. This unique relationship of sets is different for each species of microalgae. Therefore, by observing the particular relationship of sets, we successfully identified different algae such as Isochrysis galbana, Emiliania huxleyi, Thalassiosira weissflogii, Nannochloris sp., Skeletonema cf. costatum, and Tetraselmis chui. This simple and cost-effective SALDI-MS analysis method coupled with multi-nanomaterials as substrates may be extended to identify other microalgae and microorganisms in real samples. Graphical Abstract Identification of microalgae by surface-assisted laser desorption/ionization mass spectrometry coupled with three different mercury-based nanosubstrates. PMID:26842733

  16. Desorption electrospray ionization mass spectrometry: direct toxicological screening and analysis of illicit Ecstasy tablets.

    PubMed

    Leuthold, Luc Alexis; Mandscheff, Jean-François; Fathi, Marc; Giroud, Christian; Augsburger, Marc; Varesio, Emmanuel; Hopfgartner, Gérard

    2006-01-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) was used as a simple and rapid way to analyze drug tablets and powders without sample preparation. Experiments were performed with a home-made DESI source coupled to a triple-quadrupole linear-ion trap (QqQ(LIT)) mass spectrometer. Twenty-one commercial drugs as well as some illicit Ecstasy tablets and powders were analyzed. MS spectra almost exclusively showed the protonated or deprotonated ion of the drug after directing the pneumatically assisted electrospray onto the tablet's surface. With some tablets, inhomogeneity of the surface resulted in different spectra depending on the spot analyzed, thus showing that DESI could be used for imaging. Directly triggered MS/MS spectra were used for confirmatory analysis, with analysis times often below 10 s per tablet. For illicit Ecstasy tablets, DESI-MS, GC/MS and LC/MS analyses provided similar qualitative results for the main analytes. With MS/MS spectra library comparison or exact mass measurements, this technique could become very powerful for the rapid analysis of unknown tablets and shows the great potential of desorption techniques as an alternative to solution-based analysis. PMID:16331738

  17. Desorption atmospheric pressure photoionization-mass spectrometry in routine analysis of confiscated drugs.

    PubMed

    Kauppila, Tiina J; Flink, Anu; Haapala, Markus; Laakkonen, Ulla-Maija; Aalberg, Laura; Ketola, Raimo A; Kostiainen, Risto

    2011-07-15

    A comprehensive study was made, where desorption atmospheric pressure photoionization (DAPPI) was applied to the direct analysis of confiscated drugs and pharmaceuticals of various forms and matrices. The analyzed samples included herbal products [Catha edulis (khat), Psilocybe mushrooms, opium and Spice], designer drugs in tablet and powder form [e.g. meta-chlorophenylpiperazine (mCPP), 3-fluoromethamphetamine (3-FMA), methylenedioxypyrovalerone (MDPV) and methylone], and anabolic steroids in oil and tablets. The analyses were performed with ion trap mass spectrometer in MS and MS(2) modes and the obtained spectra were compared with GC-MS results. Contamination of the mass spectrometer was avoided by careful adjustment of the distance of the sample from the mass spectrometer inlet. DAPPI proved to be a fast and specific analysis technique, which does not require any sample preparation, and which therefore suits well to this type of forensic analysis. PMID:21474259

  18. Imaging of Lipids and Metabolites Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela; Laskin, Julia

    2015-01-17

    In recent years, mass spectroscopy imaging (MSI) has emerged as a foundational technique in metabolomics and drug screening providing deeper understanding of complex mechanistic pathways within biochemical systems and biological organisms. We have been invited to contribute a chapter to a new Springer series volume, entitled “Mass Spectrometry Imaging of Small Molecules”. The volume is planned for the highly successful lab protocol series Methods in Molecular Biology, published by Humana Press, USA. The volume is aimed to equip readers with step-by-step mass spectrometric imaging protocols and bring rapidly maturing methods of MS imaging to life science researchers. The chapter will provide a detailed protocol of ambient MSI by use of nanospray desorption electrospray ionization.

  19. Matrix assisted laser desorption ionization-time of flight mass spectrometry analysis of hyaluronan oligosaccharides

    PubMed Central

    Sakai, Shinobu; Hirano, Kana; Toyoda, Hidenao; Linhardt, Robert J.; Toida, Toshihiko

    2014-01-01

    A new method is presented for the identification of oligosaccharides obtained by enzymatic digestion of hyaluronan (HA) with bacterial hyaluronidase (E.C. 4.2.2.1, from Streptomyces hyalurolyticus) using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS). Mixtures containing HA oligosaccharides of tetrasaccharide (4-mer)–34-mer were analyzed using this method. The carboxyl groups of the glucuronate residues in the prepared HA oligomers, were modified as the acidic form (—COOH), sodium salts (—COONa), organic ammonium salts, or methylesters before MALDI-TOFMS measurement. Among these samples, the methylester form of glucuronate residues in HA oligosaccharides, prepared by methylation using trimethylsilyl diazomethane, afforded high sensitivity for spectra. This simple modification method for carboxyl group methylation of acidic polysaccharides [Hirano et al., Carbohydr. Res., 340, (2005) 2297–2304] provides samples suitable for MALDI-TOF mass spectrometric analysis throughout a significantly enhanced range of masses. PMID:17543609

  20. Thin-layer chromatography/desorption electrospray ionization mass spectrometry: investigation of goldenseal alkaloids.

    PubMed

    Van Berkel, Gary J; Tomkins, Bruce A; Kertesz, Vilmos

    2007-04-01

    Desorption electrospray ionization mass spectrometry was investigated as a means to qualitatively identify and to quantify analytes directly from developed normal-phase thin-layer chromatography plates. The atmospheric sampling capillary of a commercial ion trap mass spectrometer was extended to permit sampling and ionization of analytes in bands separated on intact TLC plates (up to 10 cmx10 cm). A surface positioning software package and the appropriate hardware enabled computer-controlled surface scanning along the length of development lanes or at fixed Rf value across the plates versus the stationary desorption electrospray emitter. Goldenseal (Hydrastis canadensis) and related alkaloids and commercial dietary supplements were used as standards and samples. Alkaloid standards and samples were spotted and separated on aluminum- or glass-backed plates using established literature methods. The mass spectral signal levels as a function of desorption spray solvent were investigated with acetonitrile proving superior to methanol. The detection levels (approximately 5 ng each or 14-28 pmol) in mass spectral full-scan mode were determined statistically from the calibration curves (2.5-100 pmol) for the standards berberine, palmatine, and hydrastinine spotted as a mixture and separated on the plates. Qualitative screening of the major alkaloids present in six different over-the-counter "goldenseal" dietary supplements was accomplished by obtaining full-scan mass spectra during surface scans along the development lane in the direction of increasing Rf value. In one sample, alkaloids were detected that strongly suggested the presence of at least one additional herb undeclared on the product label. These same data indicated the misidentification of one of the alkaloids in the TLC literature. Quantities of the alkaloids present in two of the samples determined using the mass spectral data were in reasonable agreement with the label values, indicating the quantitative

  1. Trace Level Detection of Explosives in Solution Using Leidenfrost Phenomenon Assisted Thermal Desorption Ambient Mass Spectrometry

    PubMed Central

    Saha, Subhrakanti; Mandal, Mridul Kanti; Chen, Lee Chuin; Ninomiya, Satoshi; Shida, Yasuo; Hiraoka, Kenzo

    2013-01-01

    The present paper demonstrates the detection of explosives in solution using thermal desorption technique at a temperature higher than Leidenfrost temperature of the solvent in combination with low temperature plasma (LTP) ionization. Leidenfrost temperature of a solvent is the temperature above which the solvent droplet starts levitation instead of splashing when placed on a hot metallic surface. During this desorption process, slow and gentle solvent evaporation takes place, which leads to the pre-concentration of less-volatile explosive molecules in the droplet and the explosive molecules are released at the last moment of droplet evaporation. The limits of detection for explosives studied by using this thermal desorption LTP ionization method varied in a range of 1 to 10 parts per billion (ppb) using a droplet volume of 20 μL (absolute sample amount 90–630 fmol). As LTP ionization method was applied and ion–molecule reactions took place in ambient atmosphere, various ion–molecule adduct species like [M+NO2]−, [M+NO3]−, [M+HCO3]−, [M+HCO4]− were generated together with [M−H]− peak. Each peak was unambiguously identified using ‘Exactive Orbitrap’ mass spectrometer in negative ionization mode within 3 ppm deviation compared to its exact mass. This newly developed technique was successfully applied to detect four explosives contained in the pond water and soil sample with minor sample pre-treatment and the explosives were detected with ppb levels. The present method is simple, rapid and can detect trace levels of explosives with high specificity from solutions. PMID:24349927

  2. Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

    2009-06-01

    The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

  3. Analytical laser induced liquid beam desorption mass spectrometry of protonated amino acids and their non-covalently bound aggregates

    NASA Astrophysics Data System (ADS)

    Charvat, A.; Lugovoj, E.; Faubel, M.; Abel, B.

    2002-09-01

    We have used analytical laser induced liquid beam desorption in combination with high resolution mass spectrometry (m/Δ mgeq 1 000) for the study of protonated amino acids (ornithine, citrulline, lysine, arginine) and their non-covalently bound complexes in the gas phase desorbed from water solutions. We report studies in which the desorption mechanism has been investigated. The results imply that biomolecule desorption at our conditions is a single step process involving laser heating of the solvent above its supercritical temperature, a rapid expansion, ion recombination and finally isolation and desorption of only a small fraction of preformed ions and charged aggregates. In addition, we report an investigation of the aqueous solution concentration and pH-dependence of the laser induced desorption of protonated species (monomers and dimers). The experimental findings suggest that the desorption process depends critically upon the proton affinity of the molecules, the concentration of other ions, and of the pH value of the solution. Therefore the ion concentrations measured in the gas phase very likely reflect solution properties (equilibrium concentrations). Arginine self-assembles large non-covalent singly protonated multimers (n=1...8) when sampled by IR laser induced water beam desorption mass spectrometry. The structures of these aggregates may resemble those of the solid state and may be preformed in solution prior to desorption. A desorption of mixtures of amino acids in water solution enabled us to study (mixed) protonated dimers, one of the various applications of the present technique. Reasons for preferred dimerization leading to simple cases of molecular recognition as well as less preferred binding is discussed in terms of the number of specific H-bonds that can be established in the clusters.

  4. Electrospray-assisted laser desorption/ionization and tandem mass spectrometry of peptides and proteins.

    PubMed

    Peng, Ivory X; Shiea, Jentaie; Ogorzalek Loo, Rachel R; Loo, Joseph A

    2007-01-01

    We have constructed an electrospray-assisted laser desorption/ionization (ELDI) source which utilizes a nitrogen laser pulse to desorb intact molecules from matrix-containing sample solution droplets, followed by electrospray ionization (ESI) post-ionization. The ELDI source is coupled to a quadrupole ion trap mass spectrometer and allows sampling under ambient conditions. Preliminary data showed that ELDI produces ESI-like multiply charged peptides and proteins up to 29 kDa carbonic anhydrase and 66 kDa bovine albumin from single-protein solutions, as well as from complex digest mixtures. The generated multiply charged polypeptides enable efficient tandem mass spectrometric (MS/MS)-based peptide sequencing. ELDI-MS/MS of protein digests and small intact proteins was performed both by collisionally activated dissociation (CAD) and by nozzle-skimmer dissociation (NSD). ELDI-MS/MS may be a useful tool for protein sequencing analysis and top-down proteomics study, and may complement matrix-assisted laser desorption/ionization (MALDI)-based measurements. PMID:17639579

  5. Direct protein detection from biological media through electrospray-assisted laser desorption ionization/mass spectrometry.

    PubMed

    Huang, Min-Zong; Hsu, Hsiu-Jung; Lee, Jen-Yih; Jeng, Jingyueh; Shiea, Jentaie

    2006-05-01

    We report here using a novel technology-electrospray-assisted laser desorption ionization (ELDI)/mass spectrometry-for the rapid and sensitive detection of the major proteins that exist in dried biological fluids (e.g., blood, tears, saliva, serum), bacterial cultures, and tissues (e.g., porcine liver and heart) under ambient conditions. This technique required essentially no sample pretreatment. The proteins in the samples were desorbed using a pulsed nitrogen laser without the assistance of an organic matrix. The desorbed protein molecules were then post-ionized through their fusion into the charged solvent droplets produced from the electrospray of an acidic methanol solution; electrospray ionization (ESI) proceeded from the newly formed droplets to generate the ESI-like protein ions. This new ionization approach combines some of the features of electrospray ionization with those of matrix-assisted laser desorption ionization (MALDI), that is, sampling of a solid surface with spatial resolution, generating ESI-like mass spectra of the desorbed proteins, and operating under ambient conditions. PMID:16674100

  6. Laser desorption mass spectrometry and small angle neutron scattering of heavy fossil materials

    SciTech Connect

    Hunt, J.E.; Winans, R.E.; Thiyagarajan, P.

    1997-09-01

    The determination of the structural building blocks and the molecular weight range of heavy hydrocarbon materials is of crucial importance in research on their reactivity and for their processing. The chemically and physically heterogenous nature of heavy hydrocarbon materials, such as coals, heavy petroleum fractions, and residues, dictates that their structure and reactivity patterns be complicated. The problem is further complicated by the fact that the molecular structure and molecular weight distribution of these materials is not dependent on a single molecule, but on a complex mixture of molecules which vary among coals and heavy petroleum samples. Laser Desorption mass spectrometry (LDMS) is emerging as a technique for molecular weight determination having found widespread use in biological polymer research, but is still a relatively new technique in the fossil fuel area. Small angle neutron scattering (SANS) provides information on the size and shape of heavy fossil materials. SANS offers the advantages of high penetration power even in thick cells at high temperatures and high contrast for hydrocarbon systems dispersed in deuterated solvents. LDMS coupled with time of flight has the advantages of high sensitivity and transmission and high mass range. We have used LDMS to examine various heavy fossil-derived materials including: long chain hydrocarbons, asphaltenes from petroleum vacuum resids, and coals. This paper describes the application of laser desorption and small angle neutron scattering techniques to the analysis of components in coals, petroleum resids and unsaturated polymers.

  7. Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

    NASA Astrophysics Data System (ADS)

    Winter, Gregory T.; Wilhide, Joshua A.; LaCourse, William R.

    2016-02-01

    Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

  8. Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography.

    PubMed

    Winter, Gregory T; Wilhide, Joshua A; LaCourse, William R

    2016-02-01

    Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot. PMID:26471042

  9. Molecular Surface Sampling and Chemical Imaging using Proximal Probe Thermal Desorption/Secondary Ionization Mass Spectrometry

    SciTech Connect

    Ovchinnikova, Olga S; Kertesz, Vilmos; Van Berkel, Gary J

    2011-01-01

    Proximal probe thermal desorption/secondary ionization mass spectrometry was studied and applied to molecular surface sampling and chemical imaging using printed patterns on photopaper as test substrates. With the use of a circular cross section proximal probe with a tip diameter of 50 m and fixed temperature (350 C), the influence of probe-to-surface distance, lane scan spacing, and surface scan speed on signal quality and spatial resolution were studied and optimized. As a compromise between signal amplitude, signal reproducibility, and data acquisition time, a surface scan speed of 100 m/s, probe-to-paper surface distance of 5 m, and lane spacing of 10 m were used for imaging. Under those conditions the proximal probe thermal desorption/secondary ionization mass spectrometry method was able to achieve a spatial resolution of about 50 m as determined by the ability to distinguish surface patterns of known dimensions that were printed on the paper substrate. It is expected that spatial resolution and chemical image quality could be further improved by using probes of smaller cross section size and by incorporating a means to maintain a fixed optimal probe-to-surface distance real time, continuously adapting to the changing topography of the surface during a lane scan.

  10. Microfabricated glow discharge plasma (MFGDP) for ambient desorption/ionization mass spectrometry.

    PubMed

    Ding, Xuelu; Zhan, Xuefang; Yuan, Xin; Zhao, Zhongjun; Duan, Yixiang

    2013-10-01

    A novel ambient ionization technique for mass spectrometry, microfabricated glow discharge plasma (MFGDP), is reported. This device is made of a millimeter-sized ceramic cavity with two platinum electrodes positioned face-to-face. He or Ar plasma can be generated by a direct current voltage of several hundreds of volts requiring a total power below 4 W. The thermal plume temperature of the He plasma was measured and found to be between 25 and 80 °C at a normal discharge current. Gaseous, liquid, creamy, and solid samples with molecular weights up to 1.5 kDa could be examined in both positive and negative mode, giving limits of detection (LOD) at or below the fg/mm(2) level. The relative standard deviation (RSD) of manual sampling ranged from 10% to ~20%, while correlation coefficients of the working curve (R(2)) are all above 0.98 with the addition of internal standards. The ionization mechanisms are examed via both optical and mass spectrometry. Due to the low temperature characteristics of the microplasma, nonthermal momentum desorption is considered to dominate the desorption process. PMID:24000803

  11. Laser desorption time-of-flight mass spectrometry of vacuum UV photo-processed methanol ice

    NASA Astrophysics Data System (ADS)

    Paardekooper, D. M.; Bossa, J.-B.; Linnartz, H.

    2016-07-01

    Context. Methanol in the interstellar medium mainly forms upon sequential hydrogenation of solid CO. With typical abundances of up to 15% (with respect to water) it is an important constituent of interstellar ices where it is considered as a precursor in the formation of large and complex organic molecules (COMs), e.g. upon vacuum UV (VUV) photo-processing or exposure to cosmic rays. Aims: This study aims at detecting novel complex organic molecules formed during the VUV photo-processing of methanol ice in the laboratory using a technique more sensitive than regular surface diagnostic tools. In addition, the formation kinetics of the main photo-products of methanol are unravelled for an astronomically relevant temperature (20 K) and radiation dose. Methods: The VUV photo-processing of CH3OH ice is studied by applying laser desorption post-ionisation time-of-flight mass spectrometry (LDPI TOF-MS), and analysed by combining molecule-specific fragmentation and desorption features. Results: The mass spectra correspond to fragment ions originating from a number of previously recorded molecules and from new COMs, such as the series (CO)xH, with x = 3 and y < 3x-1, to which prebiotic glycerin belongs. The formation of these large COMs has not been reported in earlier photolysis studies and suggests that such complex species may form in the solid state under interstellar conditions.

  12. Heavy resid asphaltene characterization using high resolution and laser desorption mass spectrometry

    SciTech Connect

    Hunt, J.E.; Kim, Y.; Winans, R.E.

    1995-12-31

    Resid is the nondistillable portion of crude oil, generally thought to consist largely of unsaturated molecules of considerable size and ring number. Such molecules must be upgraded to more saturated compounds if they are to be used as fuel sources. Current processing of resid is performed though coking, thermal and catalytic cracking, deasphalting and hydroprocessing. Thermal treatments, however, produce large quantities of low-value coke and hydroprocessing is expensive. Asphaltenes comprise the most process resistant portion of the resid. They contain high concentrations of heteroatoms and a high degree of unsaturation. Because these undesirable characteristics are concentrated in asphaltenes, finding an improved method of upgrading asphaltenes is a prerequisite to improving the upgrading of whole resid to viable fuel. Asphaltenes have, at present, only an operational definition. They are insoluble in straight chain saturated hydrocarbons. Very little is known about the structure of compounds in asphaltenes. They are a highly diverse group of compounds that are resistant to analysis by conventional methods. Conclusions about the structures of asphaltenes tends to be speculative. In this study desorption electron impact (HREIMS), chemical ionization high resolution mass spectrometry (HRCIMS), and laser desorption mass spectrometry (LD) have been applied to deasphalted oils (DAO) and asphaltenes derived from heavy Maya resid. LD data should yield information on the high molecular weight aromatic compounds, while HRMS can provide molecular characterization.

  13. Desorption ElectroSpray Ionization - Orbitrap Mass Spectrometry of synthetic polymers and copolymers.

    PubMed

    Friia, Manel; Legros, Véronique; Tortajada, Jeanine; Buchmann, William

    2012-08-01

    Desorption ElectroSpray Ionization (DESI) - Orbitrap Mass Spectrometry (MS) was evaluated as a new tool for the characterization of various industrial synthetic polymers (poly(ethylene glycol), poly(propylene glycol), poly(methylmethacrylate), poly(dimethylsiloxane)) and copolymers, with masses ranging from 500 g.mol(-1) up to more than 20 000 g.mol(-1) . Satisfying results in terms of signal stability and sensitivity were obtained from hydrophobic surfaces (HTC Prosolia) with a mixture water/methanol (10/90) as spray solvent in the presence of sodium salt. Taking into account the formation of multiplied charged species by DESI-MS, a strategy based on the use of a deconvolution software followed by the automatic assignment of the ions was described allowing the rapid determination of M(n) , M(w) and PDI values. DESI-Orbitrap MS results were compared to those obtained from matrix-assisted laser desorption/ionization- time-of-flight MS and gel permeation chromatography. An application of DESI-Orbitrap MS for the detection and identification of polymers directly from cosmetics was described. PMID:22899511

  14. Multivariate analysis of progressive thermal desorption coupled gas chromatography-mass spectrometry.

    SciTech Connect

    Van Benthem, Mark Hilary; Mowry, Curtis Dale; Kotula, Paul Gabriel; Borek, Theodore Thaddeus, III

    2010-09-01

    Thermal decomposition of poly dimethyl siloxane compounds, Sylgard{reg_sign} 184 and 186, were examined using thermal desorption coupled gas chromatography-mass spectrometry (TD/GC-MS) and multivariate analysis. This work describes a method of producing multiway data using a stepped thermal desorption. The technique involves sequentially heating a sample of the material of interest with subsequent analysis in a commercial GC/MS system. The decomposition chromatograms were analyzed using multivariate analysis tools including principal component analysis (PCA), factor rotation employing the varimax criterion, and multivariate curve resolution. The results of the analysis show seven components related to offgassing of various fractions of siloxanes that vary as a function of temperature. Thermal desorption coupled with gas chromatography-mass spectrometry (TD/GC-MS) is a powerful analytical technique for analyzing chemical mixtures. It has great potential in numerous analytic areas including materials analysis, sports medicine, in the detection of designer drugs; and biological research for metabolomics. Data analysis is complicated, far from automated and can result in high false positive or false negative rates. We have demonstrated a step-wise TD/GC-MS technique that removes more volatile compounds from a sample before extracting the less volatile compounds. This creates an additional dimension of separation before the GC column, while simultaneously generating three-way data. Sandia's proven multivariate analysis methods, when applied to these data, have several advantages over current commercial options. It also has demonstrated potential for success in finding and enabling identification of trace compounds. Several challenges remain, however, including understanding the sources of noise in the data, outlier detection, improving the data pretreatment and analysis methods, developing a software tool for ease of use by the chemist, and demonstrating our belief that

  15. Ammonium Ion Exchanged Zeolite for Laser Desorption/Ionization Mass Spectrometry of Phosphorylated Peptides

    PubMed Central

    Yang, Mengrui; Fujino, Tatsuya

    2015-01-01

    α-Cyano-4-hydroxycinnamic acid (CHCA), an organic matrix molecule for matrix-assisted laser desorption/ionization mass spectrometry, was adsorbed to NH4+-type zeolite surface, and this new matrix was used for the detection of low-molecular-weight compounds. It was found that this matrix could simplify the mass spectrum in the low-molecular-weight region and prevent interference from fragments and alkali metal ion adducted species. CHCA adsorbed to NH4+-type ZSM5 zeolite (CHCA/NH4ZSM5) was used to measure atropine and aconitine, two toxic alkaloids in plants. In addition, CHCA/NH4ZSM5 enabled us to detect phosphorylated peptides; peaks of the protonated peptides had higher intensities than the peaks observed using CHCA only. PMID:26448749

  16. Matrix-Assisted Laser Desorption Ionization Imaging Mass Spectrometry: In Situ Molecular Mapping

    PubMed Central

    Angel, Peggi M.; Caprioli, Richard M.

    2013-01-01

    Matrix-assisted laser desorption ionization imaging mass spectrometry (IMS) is a relatively new imaging modality that allows mapping of a wide range of biomolecules within a thin tissue section. The technology uses a laser beam to directly desorb and ionize molecules from discrete locations on the tissue that are subsequently recorded in a mass spectrometer. IMS is distinguished by the ability to directly measure molecules in situ ranging from small metabolites to proteins, reporting hundreds to thousands of expression patterns from a single imaging experiment. This article reviews recent advances in IMS technology, applications, and experimental strategies that allow it to significantly aid in the discovery and understanding of molecular processes in biological and clinical samples. PMID:23259809

  17. Atomic Force Microscope Controlled Topographical Imaging and Proximal Probe Thermal Desorption/Ionization Mass Spectrometry Imaging

    SciTech Connect

    Ovchinnikova, Olga S; Kjoller, Kevin; Hurst, Gregory {Greg} B; Pelletier, Dale A; Van Berkel, Gary J

    2014-01-01

    This paper reports on the development of a hybrid atmospheric pressure atomic force microscopy/mass spectrometry imaging system utilizing nano-thermal analysis probes for thermal desorption surface sampling with subsequent atmospheric pressure chemical ionization and mass analysis. The basic instrumental setup and the general operation of the system were discussed and optimized performance metrics were presented. The ability to correlate topographic images of a surface with atomic force microscopy and a mass spectral chemical image of the same surface, utilizing the same probe without moving the sample from the system, was demonstrated. Co-registered mass spectral chemical images and atomic force microscopy topographical images were obtained from inked patterns on paper as well as from a living bacterial colony on an agar gel. Spatial resolution of the topography images based on pixel size (0.2 m x 0.8 m) was better than the resolution of the mass spectral images (2.5 m x 2.0 m), which were limited by current mass spectral data acquisition rate and system detection levels.

  18. Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

    2011-04-15

    Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. PMID:21416534

  19. Cobalt coated substrate for matrix-free analysis of small molecules by laser desorption/ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yalcin, Talat; Li, Liang

    2009-12-01

    Small molecule analysis is one of the most challenging issues in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. We have developed a cobalt coated substrate as a target for matrix-free analysis of small molecules in laser desorption/ionization mass spectrometry. Cobalt coating of 60-70 nm thickness has been characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and laser induced breakdown spectroscopy. This target facilitates hundreds of samples to be spotted and analyzed without mixing any matrices, in a very short time. This can save a lot of time and money and can be a very practical approach for the analysis of small molecules by laser desorption/ionization mass spectrometry.

  20. Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

    SciTech Connect

    Jill R. Scott; Beizhan Yan; Daphne L. Stoner; J. Michelle Kotler; Nancy W. Hinman

    2007-04-01

    Identification of mineral-associated biosignatures is of significance for retrieving biochemical information from geological records here on Earth and detecting signs of life on other planets, such as Mars. The importance of the geomatrix for identifying amino acids (e.g., histidine, threonine, and cysteine) and small proteins (e.g., gramicidin S) was investigated by laser desorption Fourier transform mass spectrometry. The investigated geomatrices include analogues of Fe-bearing minerals such as hematite and Na-bearing evaporites (e.g., halite). Samples were prepared by two methods: 1) application of analyte to the geomatrix surface and 2) production of homogenous analyte:geomatrix mixtures. Comparison of the two sample preparation methods revealed that the mixing method produces a better signal/noise ratio than surface application for the analyses of amino acids. The composition of the geomatrix has a profound influence on the detection of biomolecules. Peaks corresponding to the cation-attached biomolecular ions were observed for the Na-bearing evaporite analogue. No detectable peaks for the biomolecular ion species were observed when the biomolecules were associated with Fe-bearing minerals. Instead, only minor peaks were observed that may correspond to ions from fragments of the biomolecules. Depending on the underlying mineral composition, geomatrix-assisted laser desorption/ionization shows promise for directly identifying biosignatures associated with minerals.

  1. Characterization of ballpoint pen inks by thermal and desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2005-09-01

    The characterization of ink on paper is of importance for dating and comparing questioned ink entries in forensic document examination. Inks are commonly characterized by their colorant profile that is identified by well-established analytical methods. Numerous ink formulations show identical colorant profiles, though. In order to differentiate inks that are not distinguishable by colorant analysis, a method for the characterization of colorless ink ingredients, namely binders, solvents and additives is necessary. In this paper, we propose a technique for the analysis of colorless compounds in ballpoint inks using direct thermal desorption of the ink on paper followed by chemical analysis of the desorbed volatile compounds by gas chromatography-mass spectrometry. As compared to liquid extraction and subsequent analysis of the extracts, the technique avoids possible contamination risks. Sensitivity is very high due to the enrichment of volatile components by thermal desorption. Even from old samples, the chromatograms obtained by the method enable the determination of binder polymers, solvents and additives. Pure binders as used by ink manufacturers were analyzed for unambiguous assignment of analytical results to specific polymers. To prove the practical applicability, we analyzed 121 ballpoint pens, not all having the same colorant profile, and grouped the pens into resin and solvent categories. PMID:16225233

  2. Electroless plating of silver nanoparticles on porous silicon for laser desorption/ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yan, Hong; Xu, Ning; Huang, Wen-Yi; Han, Huan-Mei; Xiao, Shou-Jun

    2009-03-01

    An improved DIOS (desorption ionization on porous silicon) method for laser desorption/ionization mass spectrometry (LDI MS) by electroless plating of silver nanoparticles (AgNPs) on porous silicon (PSi) was developed. By addition of 4-aminothiophenol (4-ATP) into the AgNO3 plating solution, the plating speed can be slowed down and simultaneously 4-ATP self-assembled monolayers (SAMs) on AgNPs (4-ATP/AgNPs) were formed. Both AgNPs and 4-ATP/AgNPs coated PSi substrates present much higher stability, sensitivity and reproducibility for LDI MS than the un-treated porous silicon ones. Their shelf life in air was tested for several weeks to a month and their mass spectra still displayed the same high quality and sensitivity as the freshly prepared ones. And more 4-ATP SAMs partly play a role of matrix to increase the ionization efficiency. A small organic molecule of tetrapyridinporphyrin (TPyP), oligomers of polyethylene glycol (PEG 400 and 2300), and a peptide of oxytocin were used as examples to demonstrate the feasibility of the silver-plated PSi as a matrix-free-like method for LDI MS. This approach can obtain limits of detection to femtomoles for TPyP, subpicomoles for oxytocin, and picomoles for PEG 400 and 2300, comparable to the traditional matrix method and much better than the DIOS method. It simplifies the sample preparation as a matrix-free-like method without addition of matrix molecules and homogenizes the sample spread over the spot for better and more even mass signals.

  3. Isomeric differentiation of polycyclic aromatic hydrocarbons using silver nitrate reactive desorption electrospray ionization mass spectrometry

    PubMed Central

    Eftekhari, Mohammad; Ismail, Ali I.; Zare, Richard N.

    2014-01-01

    RATIONALE Polycyclic aromatic hydrocarbons (PAHs) are nonpolar and difficult to detect by desorption electrospray ionization. We present a new detection method based on cationization with silver ions, which has the added advantage of being able to differentiate PAHs with the same mass but different structure. METHODS 9,10-Diphenylanthracene and triptycene, in addition to four different groups of PAH isomers: (1) anthracene and phenanthrene, (2) pyrene and fluoranthene, (3) benz[a]anthracene, benz[b]anthracene (tetracene), and chrysene (4) benzo[a]pyrene and benzo[k]fluoranthene, were deposited on a paper surface and bombarded with methanol droplets containing silver nitrate. The resulting microdroplets entered a quadruple mass spectrometer for mass analysis. RESULTS The mass spectrum shows [PAH]+, [Ag + OH + PAH]+, and [Ag(PAH)n]+ n (n = 1, 2) (and [PAH + O2]+ in the case of benz[b]anthracene) ions. PAHs having a bay structure, such as phenanthrene, showed a different tendency to interact with silver ions from those PAHs having a linear arrangement of the fused benzene rings, such as anthracene. The ratios of the [PAH]+ peak intensity to that of [Ag–PAH]+, [Ag + OH + PAH]+, [Ag(PAH)2]+, and [PAH + O2]+ were used to differentiate the PAH isomers sharing the same molecular formula with different structures. For isomeric mixtures the [PAH]+ to [Ag + OH + PAH]+ ratio was found to be the most useful parameter. The uncertainty in the mole fraction of an isomeric mixture was ±0.09, 0.13, ±0.25, and ±0.1 for phenanthrene-anthracene, fl benz[a] anthracene-chrysene, and benzo[a]pyrene-benzo[k]fluoranthene, respectively. CONCLUSIONS A simple method has been developed for the detection of PAHs in desorption electrospray ionization mass spectrometry based on Ag(I) cationization. The method showed a capability to differentiate PAHs isomers (having the same molecular mass) in isomeric mixture with an uncertainty in the mole fraction of about 0.1. At high inlet temperature

  4. Analysis of mainstream and sidestream cigarette smoke particulate matter by laser desorption mass spectrometry.

    PubMed

    Schramm, Sébastien; Carré, Vincent; Scheffler, Jean-Luc; Aubriet, Frédéric

    2011-01-01

    Laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI-FTICRMS) was used to investigate particulate matter (PM) associated with mainstream (MSS) and sidestream cigarette smokes (SSS). The high mass resolution and the high mass measurement accuracy allowed a molecular formula for each detected signal in the 150-500 m/z range to be assigned. The high number of peaks observed in mass spectra required additional data processing to extract information. In this context, Kendrick maps and Van Krevelen diagrams were drawn. These postacquisition treatments were used to more easily compare different cigarette smokes: (i) MSS from different cigarettes and (ii) MSS and SSS from the same cigarette. In both ion detection modes, most of the detected species were found to be attributed to C(6-31)H(2-35)N(0-7)O(0-9) compounds. The compounds observed in the study of SSS appeared to be more unsaturated and less oxygenated than those observed when MSS of the same cigarette was investigated. PMID:21126024

  5. Direct analysis of Stevia leaves for diterpene glycosides by desorption electrospray ionization mass spectrometry.

    PubMed

    Jackson, Ayanna U; Tata, Alessandra; Wu, Chunping; Perry, Richard H; Haas, George; West, Leslie; Cooks, R Graham

    2009-05-01

    The analysis of Stevia leaves has been demonstrated without any sample preparation using desorption electrospray ionization (DESI) mass spectrometry. Direct rapid analysis was achieved using minimal amounts of sample ( approximately 0.15 cm x 0.15 cm leaf fragment). Characteristic constituents of the Stevia plant are observed in both the positive and negative ion modes including a series of diterpene 'sweet' glycosides. The presence of the glycosides was confirmed via tandem mass spectrometry analysis using collision-induced dissociation and further supported by exact mass measurements using an LTQ-Orbitrap. The analysis of both untreated and hexane-extracted dry leaves proved that DESI can be successfully used to analyze untreated leaf fragments as identical profiles were obtained from both types of samples. Characterization and semi-quantitative determination of the glycosides was achieved based on the glycoside profile within the full mass spectrum. In addition, the presence of characteristic glycosides in an all-natural commercial Stevia dietary supplement was confirmed. This study provides an example of the application of DESI to direct screening of plant materials, in this case diterpene glycosides. PMID:19381377

  6. Direct Surface Analysis of Fungal Species by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

    SciTech Connect

    Valentine, Nancy B. ); Wahl, Jon H. ); Kingsley, Mark T. ); Wahl, Karen L. )

    2001-12-01

    Intact spores and/or hyphae of Aspergillus niger, Rhizopus oryzae, Trichoderma reesei and Phanerochaete chrysosporium are analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This study investigates various methods of sample preparation and matrices to determine optimum collection and analysis criteria for fungal analysis by MALDI-MS. Fungi are applied to the MALDI sample target as untreated, sonicated, acid/heat treated, or blotted directly from the fungal culture with double-stick tape. Ferulic acid or sinapinic acid matrix solution is layered over the dried samples and analyzed by MALDI-MS. Statistical analysis of the data show that simply using double stick tape to collect and transfer to a MALDI sample plate typically worked as well as the other preparation methods, but requires the least sample handling.

  7. Shotgun Approach for Quantitative Imaging of Phospholipids Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Thomas, Mathew; Laskin, Julia

    2014-02-04

    Mass spectrometry imaging (MSI) has been extensively used for determining spatial distributions of molecules in biological samples, and there is increasing interest in using MSI for quantification. Nanospray desorption electrospray ionization, or nano-DESI, is an ambient MSI technique where a solvent is used for localized extraction of molecules followed by nanoelectrospray ionization. Doping the nano-DESI solvent with carefully selected standards enables online quantification during MSI experiments. In this proof-of-principle study, we demonstrate this quantification approach can be extended to provide shotgun-like quantification of phospholipids in thin brain tissue sections. Specifically, two phosphatidylcholine (PC) standards were added to the nano-DESI solvent for simultaneous imaging and quantification of 22 PC species observed in nano-DESI MSI. Furthermore, by combining the quantitative data obtained in the individual pixels, we demonstrate quantification of these PC species in seven different regions of a rat brain tissue section.

  8. Development and Applications of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Zheng, Qiuling; Chen, Hao

    2016-06-12

    Desorption electrospray ionization mass spectrometry (DESI-MS) is a recent advance in the field of analytical chemistry. This review surveys the development of liquid sample DESI-MS (LS-DESI-MS), a variant form of DESI-MS that focuses on fast analysis of liquid samples, and its novel analy-tical applications in bioanalysis, proteomics, and reaction kinetics. Due to the capability of directly ionizing liquid samples, liquid sample DESI (LS-DESI) has been successfully used to couple MS with various analytical techniques, such as microfluidics, microextraction, electrochemistry, and chromatography. This review also covers these hyphenated techniques. In addition, several closely related ionization methods, including transmission mode DESI, thermally assisted DESI, and continuous flow-extractive DESI, are briefly discussed. The capabilities of LS-DESI extend and/or complement the utilities of traditional DESI and electrospray ionization and will find extensive and valuable analytical application in the future. PMID:27145689

  9. Development and Applications of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zheng, Qiuling; Chen, Hao

    2016-06-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) is a recent advance in the field of analytical chemistry. This review surveys the development of liquid sample DESI-MS (LS-DESI-MS), a variant form of DESI-MS that focuses on fast analysis of liquid samples, and its novel analy-tical applications in bioanalysis, proteomics, and reaction kinetics. Due to the capability of directly ionizing liquid samples, liquid sample DESI (LS-DESI) has been successfully used to couple MS with various analytical techniques, such as microfluidics, microextraction, electrochemistry, and chromatography. This review also covers these hyphenated techniques. In addition, several closely related ionization methods, including transmission mode DESI, thermally assisted DESI, and continuous flow–extractive DESI, are briefly discussed. The capabilities of LS-DESI extend and/or complement the utilities of traditional DESI and electrospray ionization and will find extensive and valuable analytical application in the future.

  10. Molecular Characterization of Organic Aerosols Using Nanospray Desorption/Electrospray Ionization-Mass Spectrometry

    SciTech Connect

    Roach, Patrick J.; Laskin, Julia; Laskin, Alexander

    2010-10-01

    Nanospray desorption electrospray ionization (Nano-DESI) combined with high-resolution mass spectrometry (HR/MS) is a promising approach for detailed chemical characterization of atmospheric organic aerosol (OA) collected in laboratory and field experiments. In Nano-DESI analyte is desorbed into a solvent bridge formed between two capillaries and the analysis surface, which enables fast and efficient characterization of OA collected on substrates without special sample preparation. Stable signals achieved using Nano-DESI make it possible to obtain high-quality HR/MS data using only a small amount of material (<10 ng). Furthermore, Nano-DESI enables efficient detection of chemically labile compounds in OA, which is important for understanding chemical aging phenomena.

  11. Reconstruction and feature selection for desorption electrospray ionization mass spectroscopy imagery

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhu, Liangjia; Norton, Isaiah; Agar, Nathalie Y. R.; Tannenbaum, Allen

    2014-03-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) provides a highly sensitive imaging technique for differentiating normal and cancerous tissue at the molecular level. This can be very useful, especially under intra-operative conditions where the surgeon has to make crucial decision about the tumor boundary. In such situations, the time it takes for imaging and data analysis becomes a critical factor. Therefore, in this work we utilize compressive sensing to perform the sparse sampling of the tissue, which halves the scanning time. Furthermore, sparse feature selection is performed, which not only reduces the dimension of data from about 104 to less than 50, and thus significantly shortens the analysis time. This procedure also identifies biochemically important molecules for further pathological analysis. The methods are validated on brain and breast tumor data sets.

  12. Miniaturizing sample spots for matrix-assisted laser desorption/ionization mass spectrometry

    PubMed Central

    Tu, Tingting; Gross, Michael L.

    2009-01-01

    The trend of miniaturization in bioanalytical chemistry is shifting from technical development to practical application. In matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), progress in miniaturizing sample spots has been driven by the needs to increase sensitivity and speed, to interface with other analytical microtechnologies, and to develop miniaturized instrumentation. We review recent developments in miniaturizing sample spots for MALDI-MS. We cover both target modification and microdispensing technologies, and we emphasize the benefits with respect to sensitivity, throughput and automation. We hope that this review will encourage further method development and application of miniaturized sample spots for MALDI-MS, so as to expand applications in analytical chemistry, protein science and molecular biology. PMID:20161086

  13. Direct analysis of samples by mass spectrometry: From elements to bio-molecules using laser ablation inductively couple plasma mass spectrometry and laser desorption/ionization mass spectrometry

    SciTech Connect

    Perdian, David C.

    2009-01-01

    Mass spectrometric methods that are able to analyze solid samples or biological materials with little or no sample preparation are invaluable to science as well as society. Fundamental research that has discovered experimental and instrumental parameters that inhibit fractionation effects that occur during the quantification of elemental species in solid samples by laser ablation inductively coupled plasma mass spectrometry is described. Research that determines the effectiveness of novel laser desorption/ionization mass spectrometric methods for the molecular analysis of biological tissues at atmospheric pressure and at high spatial resolution is also described. A spatial resolution is achieved that is able to analyze samples at the single cell level.

  14. Non-traditional applications of laser desorption/ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    McAlpin, Casey R.

    Seven studies were carried out using laser desorption/ionization mass spectrometry (LDI MS) to develop enhanced methodologies for a variety of analyte systems by investigating analyte chemistries, ionization processes, and elimination of spectral interferences. Applications of LDI and matrix assisted laser/desorption/ionization (MALDI) have been previously limited by poorly understood ionization phenomena, and spectral interferences from matrices. Matrix assisted laser desorption ionization MS is well suited to the analysis of proteins. However, the proteins associated with bacteriophages often form complexes which are too massive for detection with a standard MALDI mass spectrometer. As such, methodologies for pretreatment of these samples are discussed in detail in the first chapter. Pretreatment of bacteriophage samples with reducing agents disrupted disulfide linkages and allowed enhanced detection of bacteriophage proteins. The second chapter focuses on the use of MALDI MS for lipid compounds whose molecular mass is significantly less than the proteins for which MALDI is most often applied. The use of MALDI MS for lipid analysis presented unique challenges such as matrix interference and differential ionization efficiencies. It was observed that optimization of the matrix system, and addition of cationization reagents mitigated these challenges and resulted in an enhanced methodology for MALDI MS of lipids. One of the challenges commonly encountered in efforts to expand MALDI MS applications is as previously mentioned interferences introduced by organic matrix molecules. The third chapter focuses on the development of a novel inorganic matrix replacement system called metal oxide laser ionization mass spectrometry (MOLI MS). In contrast to other matrix replacements, considerable effort was devoted to elucidating the ionization mechanism. It was shown that chemisorption of analytes to the metal oxide surface produced acidic adsorbed species which then

  15. Rapid drug detection in oral samples by porous silicon assisted laser desorption/ionization mass spectrometry.

    PubMed

    Lowe, Rachel D; Guild, Georgia E; Harpas, Peter; Kirkbride, Paul; Hoffmann, Peter; Voelcker, Nicolas H; Kobus, Hilton

    2009-11-01

    The demand for analysis of oral fluid for illicit drugs has arisen with the increased adoption of roadside testing, particularly in countries where changes in legislation allow random roadside testing of drivers for the presence of a palette of illicit drugs such as methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA) and Delta9-tetrahydrocannabinol (THC). Oral samples are currently tested for such drugs at the roadside using an immunoassay-based commercial test kit. Positive roadside tests are sent for confirmatory laboratory analysis, traditionally by means of gas chromatography/mass spectrometry (GC/MS). We present here an alternative rapid analysis technique, porous silicon assisted laser desorption/ionization time-of-flight mass spectrometry (pSi LDI-MS), for the high-throughput analysis of oral fluids. This technique alleviates the need for sample derivatization, requires only sub-microliter sample volumes and allows fast analysis (of the order of seconds). In this study, the application of the technique is demonstrated with real samples from actual roadside testing. The analysis of oral samples resulted in detection of MA and MDMA with no extraction and analysis of THC after ethyl acetate extraction. We propose that, subject to miniaturization of a suitable mass spectrometer, this technique is well suited to underpin the deployment of oral fluid testing in the clinic, workplace and on the roadside. PMID:19844964

  16. High-Resolution Desorption Electrospray Ionization Mass Spectrometry for Chemical Characterization of Organic Aerosols

    SciTech Connect

    Laskin, Julia; Laskin, Alexander; Roach, Patrick J.; Slysz, Gordon W.; Anderson, Gordon A.; Nizkorodov, Serguei; Bones, David L.; Nguyen, Lucas

    2010-03-01

    Characterization of the chemical composition and chemical transformations of secondary organic aerosol (SOA) is both a major challenge and the area of greatest uncertainty in current aerosol research. This study presents the first application of desorption electrospray ionization combined with high-resolution mass spectrometry (DESI-MS) for detailed chemical characterization and studies of chemical aging of OA collected on Teflon substrates. DESI-MS offers unique advantages both for detailed characterization of chemically labile components in OA that cannot be detected using more traditional electrospray ionization mass spectrometry (ESI-MS) and for studying chemical aging of OA. DESI-MS enables rapid characterization of OA samples collected on substrates by eliminating the sample preparation stage. In addition, it enables detection and structural characterization of chemically labile molecules in OA samples by minimizing the residence time of analyte in the solvent. SOA produced by the ozonolysis of limonene (LSOA) was allowed to react with gaseous ammonia. Chemical aging resulted in measurable changes in the optical properties of LSOA observed using UV- visible spectroscopy. DESI-MS combined with tandem mass spectrometry experiments (MS/MS) enabled identification of species in aged LSOA responsible for absorption of the visible light. Detailed analysis of the experimental data allowed us to identify chemical changes induced by reactions of LSOA constituents with ammonia and distinguish between different mechanisms of chemical aging.

  17. New strategies for characterizing ancient proteins using matrix-assisted laser desorption ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ostrom, Peggy H.; Schall, Michael; Gandhi, Hasand; Shen, Tun-Li; Hauschka, Peter V.; Strahler, John R.; Gage, Douglas A.

    2000-03-01

    Structural characterization of ancient proteins is confounded by the small quantity of material remaining in fossils, difficulties in purification, and the inability to obtain sequence information by classical Edman degradation. We present a microbore reversed phase high performance liquid chromatography (rpHPLC) method for partial purification of small quantities (picomoles) of the bone protein osteocalcin (OC) and subsequent characterization of this material by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The presence of OC in the modern and ancient samples was suggested by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and radioimmunoassay (RIA). The SDS-PAGE of material isolated from 800 yr BP and 10,000 yr BP bones demonstrates a band consistent with the molecular weight of OC and the RIA indicated OC in concentrations of 0.2 to 450ng/mg of bone for samples between 800 and 53,000 yr BP. In modern samples, we demonstrate the use of MALDI-MS to confirm the molecular weight of intact OC and to sequence OC via peptide mass mapping and a novel derivatization approach with post-source decay analysis. MALDI-MS data for three ancient samples with RIA-confirmed osteocalcin (800 yr BP, 10,000 yr BP and 53,000 yr BP) indicate peaks with a molecular mass within the range of modern OC.

  18. Laser desorption time-of-flight mass spectrometry of ultraviolet photo-processed ices

    SciTech Connect

    Paardekooper, D. M. Bossa, J.-B.; Isokoski, K.; Linnartz, H.

    2014-10-01

    A new ultra-high vacuum experiment is described that allows studying photo-induced chemical processes in interstellar ice analogues. MATRI²CES - a Mass Analytical Tool to study Reactions in Interstellar ICES applies a new concept by combining laser desorption and time-of-flight mass spectrometry with the ultimate goal to characterize in situ and in real time the solid state evolution of organic compounds upon UV photolysis for astronomically relevant ice mixtures and temperatures. The performance of the experimental setup is demonstrated by the kinetic analysis of the different photoproducts of pure methane (CH₄) ice at 20 K. A quantitative approach provides formation yields of several new species with up to four carbon atoms. Convincing evidence is found for the formation of even larger species. Typical mass resolutions obtained range from M/ΔM ~320 to ~400 for CH₄ and argon, respectively. Additional tests show that the typical detection limit (in monolayers) is ⩽0.02 ML, substantially more sensitive than the regular techniques used to investigate chemical processes in interstellar ices.

  19. Thin-layer chromatography and mass spectrometry coupled using desorption electrospray ionization.

    PubMed

    Van Berkel, Gary J; Ford, Michael J; Deibel, Michael A

    2005-03-01

    Desorption electrospray ionization (DESI) was demonstrated as a means to couple thin-layer chromatography (TLC) with mass spectrometry. The experimental setup and its optimization are described. Development lanes were scanned by moving the TLC plate under computer control while directing the stationary DESI emitter charged droplet plume at the TLC plate surface. Mass spectral data were recorded in either selected reaction monitoring mode or in full scan ion trap mode using a hybrid triple quadrupole linear ion trap mass spectrometer. Fundamentals and practical applications of the technique were demonstrated in positive ion mode using selected reaction monitoring detection of rhodamine dyes separated on hydrophobic reversed-phase C8 plates and reversed-phase C2 plates, in negative ion full scan mode using a selection of FD&C dyes separated on a wettable reversed-phase C18 plate, and in positive ion full scan mode using a mixture of aspirin, acetaminophen, and caffeine from an over-the-counter pain medication separated on a normal-phase silica gel plate. PMID:15732898

  20. Analysis of insect cuticular hydrocarbons using matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Cvacka, Josef; Jiros, Pavel; Sobotník, Jan; Hanus, Robert; Svatos, Ales

    2006-02-01

    Insect cuticular hydrocarbons (CHCs) were probed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry with a lithium 2,5-dihydroxybenzoate matrix. CHC profiles were obtained for 12 species of diverse insect taxa (termites, ants, a cockroach, and a flesh fly). MALDI spectra revealed the presence of high molecular weight CHCs on the insect cuticle. Hydrocarbons with more than 70 carbon atoms, both saturated and unsaturated, were detected. When compared with gas chromatography/mass spectrometry (GC/MS), MALDI-TOF covered a wider range of CHCs and enabled CHCs of considerably higher molecular weight to be detected. Good congruity between GC/MS and MALDI-TOF was observed in the overlapping region of molecular weights. Moreover, a number of previously undiscovered hydrocarbons were detected in the high mass range beyond the analytical capabilities of current GC/MS instruments. MALDI was shown to hold potential to become an alternative analytical method for insect CHC analyses. The ability of MALDI to discriminate among species varying in the degree of their relatedness was found to be similar to GC/MS. However, neither MALDI-MS nor GC/MS data were able to describe the phylogenetic relationships. PMID:16555131

  1. Laser desorption/ionization mass spectrometry of diesel particulate matter with charge-transfer complexes.

    PubMed

    Carré, Vincent; Vernex-Loset, Lionel; Krier, Gabriel; Manuelli, Pascal; Muller, Jean-François

    2004-07-15

    Polycyclic aromatic hydrocarbons (PAHs) are often associated with complex matrixes such as exhaust diesel particulate matter (DPM), which complicates their study. In that case, laser desorption/ionization mass spectrometry is one of the techniques which ensures their direct analysis in the solid state. We demonstrate in this paper that the use of charge-transfer pi-complexing agents allows us to selectively detect by Fourier transform ion cyclotron resonance mass spectrometry PAHs adsorbed on diesel particles with high sensitivity. 2,4,7-trinitro-9-fluorenone and 7,7',8,8'-tetracyanoquinodimethane pi-acceptor compounds form charge-transfer complexes with PAHs and prevent their evaporation in the mass spectrometer during analysis. Moreover, the production of PAH molecular ions is dramatically increased by laser irradiation of these complexes at short wavelength (221.7 nm) and low power density (5 x 10(6) W cm(-)(2)). This methodology is applied for the first time to the examination of DPM collected during the new European driving cycle for light-duty vehicles. Differentiation criteria may coherently be assigned to engine operating mode (engine temperature, driving conditions). DPM samples can also be easily distinguished in negative ions according to the high sensitivity of this detection mode to sulfate compounds. PMID:15253632

  2. Identification of Fatty Acids, Phospholipids, and Their Oxidation Products Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry and Electrospray Ionization Mass Spectrometry

    ERIC Educational Resources Information Center

    Harmon, Christopher W.; Mang, Stephen A.; Greaves, John; Finlayson-Pitts, Barbara J.

    2010-01-01

    Electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have found increasing application in the analysis of biological samples. Using these techniques to solve problems in analytical chemistry should be an essential component of the training of undergraduate chemists. We…

  3. Atmospheric pressure laser-induced acoustic desorption chemical ionization mass spectrometry for analysis of saturated hydrocarbons.

    PubMed

    Nyadong, Leonard; Quinn, John P; Hsu, Chang S; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2012-08-21

    We present atmospheric pressure laser-induced acoustic desorption chemical ionization (AP/LIAD-CI) with O(2) carrier/reagent gas as a powerful new approach for the analysis of saturated hydrocarbon mixtures. Nonthermal sample vaporization with subsequent chemical ionization generates abundant ion signals for straight-chain, branched, and cycloalkanes with minimal or no fragmentation. [M - H](+) is the dominant species for straight-chain and branched alkanes. For cycloalkanes, M(+•) species dominate the mass spectrum at lower capillary temperature (<100 °C) and [M - H](+) at higher temperature (>200 °C). The mass spectrum for a straight-chain alkane mixture (C(21)-C(40)) shows comparable ionization efficiency for all components. AP/LIAD-CI produces molecular weight distributions similar to those for gel permeation chromatography for polyethylene polymers, Polywax 500 and Polywax 655. Coupling of the technique to Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for the analysis of complex hydrocarbon mixtures provides unparalleled mass resolution and accuracy to facilitate unambiguous elemental composition assignments, e.g., 1754 peaks (rms error = 175 ppb) corresponding to a paraffin series (C(12)-C(49), double-bond equivalents, DBE = 0) and higher DBE series corresponding to cycloparaffins containing one to eight rings. Isoabundance-contoured plots of DBE versus carbon number highlight steranes (DBE = 4) of carbon number C(27)-C(30) and hopanes of C(29)-C(35) (DBE = 5), with sterane-to-hopane ratio in good agreement with field ionization (FI) mass spectrometry analysis, but performed at atmospheric pressure. The overall speciation of nonpolar, aliphatic hydrocarbon base oil species offers a promising diagnostic probe to characterize crude oil and its products. PMID:22881221

  4. Desorption electrospray ionization mass spectrometry for trace analysis of agrochemicals in food.

    PubMed

    García-Reyes, Juan F; Jackson, Ayanna U; Molina-Díaz, Antonio; Cooks, R Graham

    2009-01-15

    Desorption electrospray ionization (DESI) is applied to the rapid, in situ, direct qualitative and quantitative (ultra)trace analysis of agrochemicals in foodstuffs. To evaluate the potential of DESI mass spectrometry (MS) in toxic residue testing in food, 16 representative multiclass agricultural chemicals (pesticides, insecticides, herbicides, and fungicides) were selected (namely, ametryn, amitraz, azoxystrobin, bitertanol, buprofezin, imazalil, imazalil metabolite, isofenphos-methyl, malathion, nitenpyram, prochloraz, spinosad, terbuthylazine, thiabendazole, and thiacloprid). The DESI-MS experiments were performed using 3 microL of solution spotted onto conventional smooth poly(tetrafluoroethylene) (PTFE) surfaces, with examination by MS and tandem mass spectrometry (MS/MS) using an ion trap mass spectrometer. Optimization of the spray solvent led to the use of acetonitrile/water (80:20) (v/v), with 1% formic acid. Most of the compounds tested showed remarkable sensitivity in the positive ion mode, approaching that attainable with conventional direct infusion electrospray mass spectrometry. To evaluate the potential of the proposed approach in real samples, different experiments were performed including the direct DESI-MS/MS analysis of fruit peels and also of fruit/vegetable extracts. The results proved that DESI allows the detection and confirmation of traces of agrochemicals in actual market-purchased samples. In addition, MS/MS confirmation of selected pesticides in spiked vegetable extracts was obtained at absolute levels as low as 1 pg for ametryn. Quantitation of imazalil residues was also undertaken using an isotopically labeled standard. The data obtained were in agreement with those from the liquid chromatography mass spectrometry (LC-MS) reference method, with relative standard deviation (RSD) values consistently below 15%. The results obtained demonstrate the sensitivity of DESI as they meet the stringent European Union pesticide regulation

  5. Transmission geometry laser desorption atmospheric pressure photochemical ionization mass spectrometry for analysis of complex organic mixtures.

    PubMed

    Nyadong, Leonard; Mapolelo, Mmilili M; Hendrickson, Christopher L; Rodgers, Ryan P; Marshall, Alan G

    2014-11-18

    We present laser desorption atmospheric pressure photochemical ionization mass spectrometry (LD/APPCI MS) for rapid throughput analysis of complex organic mixtures, without the need for matrix, electric discharge, secondary electrospray, or solvents/vaporizers. Analytes dried on a microscope slide are vaporized in transmission geometry by a laser beam aligned with the atmospheric pressure inlet of the mass spectrometer. The laser beam initiates a cascade of reactions in the region between the glass slide and MS inlet, leading to generation of reagent ions for chemical ionization of vaporized analyte. Positive analyte ions are generated predominantly by proton transfer, charge exchange, and hydride abstraction, whereas negative ions are generated by electron capture or proton transfer reactions, enabling simultaneous analysis of saturated, unsaturated, and heteroatom-containing hydrocarbons. The absence of matrix interference renders LD/APPCI MS particularly useful for analysis of small molecules (<2000 Da) such as those present in petroleum crude oil and petroleum deposits. [M + H](+) and M(+•) dominate the positive-ion mass spectra for olefins and polyaromatic hydrocarbons, whereas saturated hydrocarbons are observed mainly as [M - H](+) and/or M(+•). Heteroatom-containing hydrocarbons are observed predominantly as [M + H](+). [M - H](-) and M(-•) are the dominant negative ions observed for analytes of lower gas-phase basicity or higher electron affinity than O2. The source was coupled with a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS) to resolve and identify thousands of peaks from Athabasca bitumen heavy vacuum gas oil distillates (400-425 and 500-538 °C), enabling simultaneous characterization of their polar and nonpolar composition. We also applied LD/APPCI FTICR MS for rapid analysis of sodium and calcium naphthenate deposits with little to no sample pretreatment to provide mass spectral fingerprints that enable

  6. Flash Desorption/Mass Spectrometry for the Analysis of Less- and Nonvolatile Samples Using a Linearly Driven Heated Metal Filament

    NASA Astrophysics Data System (ADS)

    Usmanov, Dilshadbek T.; Ninomiya, Satoshi; Hiraoka, Kenzo

    2013-11-01

    In this paper, the important issue of the desorption of less- and nonvolatile compounds with minimal sample decomposition in ambient mass spectrometry is approached using ambient flash desorption mass spectrometry. The preheated stainless steel filament was driven down and up along the vertical axis in 0.3 s. At the lowest position, it touched the surface of the sample with an invasion depth of 0.1 mm in 50 ms (flash heating) and was removed from the surface (fast cooling). The heating rate corresponds to ~104 °C/s at the filament temperature of 500 °C. The desorbed gaseous molecules were ionized by using a dielectric barrier discharge ion source, and the produced ions were detected by a time-of-flight (TOF) mass spectrometer. Less-volatile samples, such as pharmaceutical tablets, narcotics, explosives, and C60 gave molecular and protonated molecule ions as major ions with thermal decomposition minimally suppressed. For synthetic polymers (PMMA, PLA, and PS), the mass spectra reflected their backbone structures because of the suppression of the sequential thermal decompositions of the primary products. The present technique appears to be suitable for high-throughput qualitative analyses of many types of solid samples in the range from a few ng to 10 μg with minimal sample consumption. Some contribution from tribodesorption in addition to thermal desorption was suggested for the desorption processes. [Figure not available: see fulltext.

  7. Development of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) for plant metabolite analysis

    SciTech Connect

    Korte, Andrew R

    2014-12-01

    This thesis presents efforts to improve the methodology of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) as a method for analysis of metabolites from plant tissue samples. The first chapter consists of a general introduction to the technique of MALDI-MSI, and the sixth and final chapter provides a brief summary and an outlook on future work.

  8. Atmospheric Pressure-Thermal Desorption (AP-TD)/Electrospray Ionization-Mass Spectrometry for the Rapid Analysis of Bacillus Spores

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A technique is described where an atmospheric pressure-thermal desorption (AP-TD) device and electrospray ionization (ESI)-mass spectrometry are coupled and used for the rapid analysis of Bacillus spores in complex matrices. The resulting AP-TD/ESI-MS technique combines the generation of volatile co...

  9. On-probe pyrolysis desorption ecectrospray ionization (DESI) mass spectrometry for the analysis of non-volatile pyrolysis products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An on-probe pyrolyzer has been constructed and interfaced with desorption electrospray ionization (DESI) mass spectrometry (MS) for the rapid analysis of non-volatile pyrolysis products. The detection and analysis of non-volatile pyrolysis products of peptides, proteins and the synthetic polymer pol...

  10. Flash desorption/mass spectrometry for the analysis of less- and nonvolatile samples using a linearly driven heated metal filament.

    PubMed

    Usmanov, Dilshadbek T; Ninomiya, Satoshi; Hiraoka, Kenzo

    2013-11-01

    In this paper, the important issue of the desorption of less- and nonvolatile compounds with minimal sample decomposition in ambient mass spectrometry is approached using ambient flash desorption mass spectrometry. The preheated stainless steel filament was driven down and up along the vertical axis in 0.3 s. At the lowest position, it touched the surface of the sample with an invasion depth of 0.1 mm in 50 ms (flash heating) and was removed from the surface (fast cooling). The heating rate corresponds to ~10(4) °C/s at the filament temperature of 500 °C. The desorbed gaseous molecules were ionized by using a dielectric barrier discharge ion source, and the produced ions were detected by a time-of-flight (TOF) mass spectrometer. Less-volatile samples, such as pharmaceutical tablets, narcotics, explosives, and C60 gave molecular and protonated molecule ions as major ions with thermal decomposition minimally suppressed. For synthetic polymers (PMMA, PLA, and PS), the mass spectra reflected their backbone structures because of the suppression of the sequential thermal decompositions of the primary products. The present technique appears to be suitable for high-throughput qualitative analyses of many types of solid samples in the range from a few ng to 10 μg with minimal sample consumption. Some contribution from tribodesorption in addition to thermal desorption was suggested for the desorption processes. Figure ᅟ PMID:23982934

  11. Identification of colorants in pigmented pen inks by laser desorption mass spectrometry.

    PubMed

    Papson, Kaitlin; Stachura, Sylwia; Boralsky, Luke; Allison, John

    2008-01-01

    Pigments are rapidly replacing dyes as colorants in pen and printer inks, due to their superior colors and stability. Unfortunately, tools commonly used in questioned document examination for analyzing pen inks, such as TLC, cannot be used for the analysis of insoluble pigments on paper. Laser desorption mass spectrometry is demonstrated here as a tool for analyzing pigment-based pen inks. A pulsed nitrogen laser can be focused onto a pen stroke from a pigmented ink pen on paper, and positive and negative ions representative of the pigment can be generated for subsequent mass spectrometric analysis. Targeted pens for this work were a set of Uni-ball 207 pigmented ink pens containing blue, light blue, orange, green, violet, red, pink, and black inks. Copper phthalocyanine was identified as the pigment used to make both blue inks. A mixture of halogenated copper phthalocyanines were identified in the green ink. Unexpectedly, the pink ink was found to contain a red pigment, Pigment Red 12, treated with a mixture of water-soluble dyes. Each sample yielded ions representative of the pigments present. PMID:18279246

  12. Desorption Electrospray Ionization Mass Spectrometry Reveals Lipid Metabolism of Individual Oocytes and Embryos

    PubMed Central

    González-Serrano, Andrés Felipe; Pirro, Valentina; Ferreira, Christina R.; Oliveri, Paolo; Eberlin, Livia S.; Heinzmann, Julia; Lucas-Hahn, Andrea; Niemann, Heiner; Cooks, Robert Graham

    2013-01-01

    Alteration of maternal lipid metabolism early in development has been shown to trigger obesity, insulin resistance, type 2 diabetes and cardiovascular diseases later in life in humans and animal models. Here, we set out to determine (i) lipid composition dynamics in single oocytes and preimplantation embryos by high mass resolution desorption electrospray ionization mass spectrometry (DESI-MS), using the bovine species as biological model, (ii) the metabolically most relevant lipid compounds by multivariate data analysis and (iii) lipid upstream metabolism by quantitative real-time PCR (qRT-PCR) analysis of several target genes (ACAT1, CPT 1b, FASN, SREBP1 and SCAP). Bovine oocytes and blastocysts were individually analyzed by DESI-MS in both positive and negative ion modes, without lipid extraction and under ambient conditions, and were profiled for free fatty acids (FFA), phospholipids (PL), cholesterol-related molecules, and triacylglycerols (TAG). Principal component analysis (PCA) and linear discriminant analysis (LDA), performed for the first time on DESI-MS fused data, allowed unequivocal discrimination between oocytes and blastocysts based on specific lipid profiles. This analytical approach resulted in broad and detailed lipid annotation of single oocytes and blastocysts. Results of DESI-MS and transcript regulation analysis demonstrate that blastocysts produced in vitro and their in vivo counterparts differed significantly in the homeostasis of cholesterol and FFA metabolism. These results should assist in the production of viable and healthy embryos by elucidating in vivo embryonic lipid metabolism. PMID:24073231

  13. Laser desorption ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons

    SciTech Connect

    Bezabeth, D.Z.; McCauley, E.M.; Kelly, P.B.; Jones, A.D.

    1994-12-31

    Polycyclic aromatic hydrocarbon (PAH) are of interest to the environmental community due to their ubiquitous presence and the carcinogenic activity of many members of this class of compounds. Recent attention has been focused on nitro-substituted PAH (nitro-PAH) because of their demonstrated mutagenic and carcinogenic activities. Nitro-PAH are found in diesel exhaust, urban air particulates, coal fly ash, and cigarette smoke. The concentration of nitro-PAH in the environment is typically one to two orders of magnitude less than the unsubstituted PAH. However, the biological activity of nitro-PAH is several orders of magnitude greater than the unsubstituted PAH. Hence, there is a need for an analytical technique which combines sensitivity as well as selectivity for nitro-PAH to allow detection of nitro-PAH over the large background of PAH in the environment. This laboratory is presently investigating the use of laser desorption ionization time-of-flight mass spectrometry as a screening method for nitro-PAH. Previous work in this laboratory examined the positive ion spectra of several nitro-PAH. Weak molecular ion peaks were observed, however, the majority of the detected ions were low mass fragments. The unsubstituted PAH were also found to produce intense positive molecular ion signals in contrast to the very weak molecular signals from the nitro-PAH. Thus, identification of the individual nitro-PAH in an environmental sample would be difficult using only the positive ion spectra.

  14. High throughput volatile fatty acid skin metabolite profiling by thermal desorption secondary electrospray ionisation mass spectrometry.

    PubMed

    Martin, Helen J; Reynolds, James C; Riazanskaia, Svetlana; Thomas, C L Paul

    2014-09-01

    The non-invasive nature of volatile organic compound (VOC) sampling from skin makes this a priority in the development of new screening and diagnostic assays. Evaluation of recent literature highlights the tension between the analytical utility of ambient ionisation approaches for skin profiling and the practicality of undertaking larger campaigns (higher statistical power), or undertaking research in remote locations. This study describes how VOC may be sampled from skin and recovered from a polydimethylsilicone sampling coupon and analysed by thermal desorption (TD) interfaced to secondary electrospray ionisation (SESI) time-of-flight mass spectrometry (MS) for the high throughput screening of volatile fatty acids (VFAs) from human skin. Analysis times were reduced by 79% compared to gas chromatography-mass spectrometry methods (GC-MS) and limits of detection in the range 300 to 900 pg cm(-2) for VFA skin concentrations were obtained. Using body odour as a surrogate model for clinical testing 10 Filipino participants, 5 high and 5 low odour, were sampled in Manilla and the samples returned to the UK and screened by TD-SESI-MS and TD-GC-MS for malodour precursors with greater than >95% agreement between the two analytical techniques. Eight additional VFAs were also identified by both techniques with chains 4 to 15 carbons long being observed. TD-SESI-MS appears to have significant potential for the high throughput targeted screening of volatile biomarkers in human skin. PMID:24992564

  15. Detection of malaria parasites in blood by laser desorption mass spectrometry.

    PubMed

    Demirev, P A; Feldman, A B; Kongkasuriyachai, D; Scholl, P; Sullivan, D; Kumar, N

    2002-07-15

    A novel method for the in vitro detection of the protozoan Plasmodium, the causative agent of malaria, has been developed. It comprises a protocol for cleanup of whole blood samples, followed by direct ultraviolet laser desorption (LD) time-of-flight mass spectrometry. Intense ion signals are observed from intact ferriprotoporphyrin IX (heme), sequestered by malaria parasites during their growth in human red blood cells. The LD mass spectrum of the heme is structure-specific, and the signal intensities are correlated with the sample parasitemia (number of parasites per unit volume of blood). Parasitemia levels on the order of 10 parasites/microL blood can be unambiguously detected by this method. Consideration of laser beam parameters (spot size, rastering across the sample surface) and actual sample consumption suggests that the detection limits can be further improved by at least an order of magnitude. The influence of experimental factors, such as desorbed ion polarity, laser exposure and fluence, sample size, and parasite growth stage, on the threshold for parasite detection is also addressed. PMID:12139027

  16. An Automated Platform for High-Resolution Tissue Imaging Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Heath, Brandi S.; Liyu, Andrey V.; Thomas, Mathew; Carson, James P.; Laskin, Julia

    2012-10-02

    An automated platform has been developed for acquisition and visualization of mass spectrometry imaging (MSI) data using nanospray desorption electrospray ionization (nano-DESI). The new system enables robust operation of the nano-DESI imaging source over many hours. This is achieved by controlling the distance between the sample and the probe by mounting the sample holder onto an automated XYZ stage and defining the tilt of the sample plane. This approach is useful for imaging of relatively flat samples such as thin tissue sections. Custom software called MSI QuickView was developed for visualization of large data sets generated in imaging experiments. MSI QuickView enables fast visualization of the imaging data during data acquisition and detailed processing after the entire image is acquired. The performance of the system is demonstrated by imaging rat brain tissue sections. High resolution mass analysis combined with MS/MS experiments enabled identification of lipids and metabolites in the tissue section. In addition, high dynamic range and sensitivity of the technique allowed us to generate ion images of low-abundance isobaric lipids. High-spatial resolution image acquired over a small region of the tissue section revealed the spatial distribution of an abundant brain metabolite, creatine, in the white and gray matter that is consistent with the literature data obtained using magnetic resonance spectroscopy.

  17. Towards monitoring of protein purification by matrix-assisted laser desorption ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jensen, Charlotte; Haebel, Sophie; Andersen, Svend Olav; Roepstorff, Peter

    1997-01-01

    The purpose of the present study is to investigate if Matrix-Assisted Laser Desorption Ionization (MALDI) Mass Spectrometry (MS) can be used as a general method for monitoring protein purification procedures. With this aim, the compatibility of MALDI/MS with protein samples containing various buffers, salts and detergents commonly used in protein purification is examined. The pH value of the sample during the crystallization process is found to be the critical point. As long as the pH value is kept below 2 by the addition of sufficiently concentrated trifluoroacetic acid (TFA), spectra can be obtained from solutions containing high concentrations of buffer or salts and up to 0.2% of sodium dodecyl sulfate (SDS). Reference spectra can be obtained by MALDI/MS of proteins electroeluted from electrophoretic gels as demonstrated using 2D-PAGE and further specificity obtained by preparing mass spectrometric peptide maps from the eluate. The value of the concept is demonstrated by relating the proteins purified from an extract of meal worm cuticle proteins with 2D-PAGE of the total extract. Finally a general strategy for monitoring protein purification by MALDI/MS is outlined and discussed.

  18. Exploration of Microplasma Probe Desorption/Ionization Mass Spectrometry (MPPDI-MS) for Biologically Related Analysis.

    PubMed

    Zhao, Zhongjun; Wang, Bo; Duan, Yixiang

    2016-02-01

    To expand the applications of glow discharge microplasma into biological analysis, an innovative ambient ion source for mass spectrometry, microplasma probe desorption/ionization mass spectrometry (MPPDI-MS), has been developed and demonstrated. Electrodes and a sampling tube were creatively combined using a stainless steel syringe needle, and efficient methods of introduction for biological samples in solid, liquid, and gaseous phases like phospholipid and amino acids were specially designed. Based on the active species generated by glow discharge plasma, simplified protonated spectra were obtained without extra solvent spray assistance. The method is easy to operate and versatile and especially has the ability to distinguish the isomeric compounds of ketone and aldehyde. Quantitative results of this method for different biological samples in different phases were also performed well. It was proved that with further improvement, this sensitive and selective analysis using MPPDI-MS with minimal invasiveness will be an ingenious tool in disease diagnosis and single-cell detections in the future. PMID:26758529

  19. Study of Electrochemical Reactions Using Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Liu, Pengyuan; Lanekoff, Ingela T.; Laskin, Julia; Dewald, Howard D.; Chen, Hao

    2012-07-03

    The combination of electrochemistry (EC) and mass spectrometry (MS) is a powerful analytical tool for studying mechanisms of redox reactions, identification of products and intermediates, and online derivatization/recognition of analytes. This work reports a new coupling interface for EC/MS by employing nanospray desorption electrospray ionization (nano-DESI), a recently developed ambient ionization method. We demonstrate online coupling of nano-DESI-MS with a traditional electrochemical flow cell, in which the electrolyzed solution emanating from the cell is ionized by nano-DESI for MS analysis. Furthermore, we show first coupling of nano-DESI-MS with an interdigitated array (IDA) electrode enabling chemical analysis of electrolyzed samples directly from electrode surfaces. Because of its inherent sensitivity, nano-DESI enables chemical analysis of small volumes and concentrations of sample solution. Specifically, good-quality signal of dopamine and its oxidized form, dopamine ortho-quinone, was obtained using 10 μL of 1 μM solution of dopamine on the IDA. Oxidation of dopamine, reduction of benzodiazepines, and electrochemical derivatization of thiol groups were used to demonstrate the performance of the technique. Our results show the potential of nano-DESI as a novel interface for electrochemical mass spectrometry research.

  20. Detection of trace ink compounds in erased handwritings using electrospray-assisted laser desorption ionization mass spectrometry.

    PubMed

    Kao, Yi-Ying; Cheng, Sy-Chyi; Cheng, Chu-Nian; Shiea, Jentaie; Ho, Hsiu-O

    2014-06-01

    Writings made with erasable pens on paper surfaces can either be rubbed off with an eraser or rendered invisible by changing the temperature of the ink. However, trace ink compounds still remain in the paper fibers even after rubbing or rendering. The detection of these ink compounds from erased handwritings will be helpful in knowing the written history of the paper. In this study, electrospray-assisted laser desorption ionization/mass spectrometry was used to characterize trace ink compounds remaining in visible and invisible ink lines. The ink compounds were desorbed from the paper surface by irradiating the handwritings with a pulsed laser beam; the desorbed analytes were subsequently ionized in an electrospray plume and detected by a quadrupole time-of-flight mass spectrometry mass analyzer. Because of the high spatial resolution of the laser beam, electrospray-assisted laser desorption ionization/mass spectrometry analysis resulted in minimal damage to the sample documents. PMID:24913397

  1. Nanostructured silicon surface modifications for as a selective matrix-free laser desorption/ionization mass spectrometry.

    PubMed

    Tsao, C W; Lin, C H; Cheng, Y C; Chien, C C; Chang, C C; Chen, W Y

    2012-06-01

    Matrix-assisted laser desorption/ionization mass spectrometry is an established soft ionization method that is widely applied to analyze biomolecules. The UV-absorbing organic matrix is essential for biomolecule ionization; however, it also creates matrix background interference, which results in problematic analyses of biomolecules of less than 700 Da. Therefore, this study investigates hydrophilic, hydrophobic cationic, anionic and immobilized metal ion surface chemical modifications to advance nanostructured silicon mass spectrometry performance (nSi-MS). This investigation provides information required for a possible novel mass spectroscopy that combines surface-enhanced and nanostructured silicon surface-assisted laser desorption/ionization mass spectrometry for the selective detection of specific compounds of a mixture. PMID:22531330

  2. Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization

    PubMed Central

    Lu, Mei; Wolff, Chloe; Cui, Weidong

    2013-01-01

    Recently we have shown that, as a versatile ionization technique, desorption electrospray ionization (DESI) can serve as a useful interface to combine electrochemistry (EC) with mass spectrometry (MS). In this study, the EC/DESI-MS method has been further applied to investigate some aqueous phase redox reactions of biological significance, including the reduction of peptide disulfide bonds and nitroaromatics as well as the oxidation of phenothiazines. It was found that knotted/enclosed disulfide bonds in the peptides apamin and endothelin could be electrochemically cleaved. Subsequent tandem MS analysis of the resulting reduced peptide ions using collision-induced dissociation (CID) and electron-capture dissociation (ECD) gave rise to extensive fragment ions, providing a fast protocol for sequencing peptides with complicated disulfide bond linkages. Flunitrazepam and clonazepam, a class of nitroaromatic drugs, are known to undergo reduction into amines which was proposed to involve nitroso and N-hydroxyl intermediates. Now in this study, these corresponding intermediate ions were successfully intercepted and their structures were confirmed by CID. This provides mass spectrometric evidence for the mechanism of the nitro to amine conversion process during nitroreduction, an important redox reaction involved in carcinogenesis. In addition, the well-known oxidation reaction of chlorpromazine was also examined. The putative transient one-electron transfer product, the chlorpromazine radical cation (m/z 318), was captured by MS, for the first time, and its structure was also verified by CID. In addition to these observations, some features of the DESI-interfaced electrochemical mass spectrometry were discussed, such as simple instrumentation and the lack of background signal. These results further demonstrate the feasibility of EC/DESI-MS for the study of the biology-relevant redox chemistry and would find applications in proteomics and drug development research. PMID

  3. Online Investigation of Aqueous-Phase Electrochemical Reactions by Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Lu, Mei; Liu, Yong; Helmy, Roy; Martin, Gary E; Dewald, Howard D; Chen, Hao

    2015-10-01

    Electrochemistry (EC) combined with mass spectrometry (MS) is a powerful tool for elucidation of electrochemical reaction mechanisms. However, direct online analysis of electrochemical reaction in aqueous phase was rarely explored. This paper presents the online investigation of several electrochemical reactions with biological relevance in the aqueous phase, such as nitrosothiol reduction, carbohydrate oxidation, and carbamazepine oxidation using desorption electrospray ionization mass spectrometry (DESI-MS). It was found that electroreduction of nitrosothiols [e.g., nitrosylated insulin B (13-23)] leads to free thiols by loss of NO, as confirmed by online MS analysis for the first time. The characteristic mass shift of 29 Da and the reduced intensity provide a quick way to identify nitrosylated species. Equally importantly, upon collision-induced dissociation (CID), the reduced peptide ion produces more fragment ions than its nitrosylated precursor ion (presumably the backbone fragmentation cannot compete with the facile NO loss for the precursor ion), thus facilitating peptide sequencing. In the case of saccharide oxidation, it was found that glucose undergoes electro-oxidation to produce gluconic acid at alkaline pH, but not at neutral and acidic pHs. Such a pH-dependent electrochemical behavior was also observed for disaccharides such as maltose and cellobiose. Upon electrochemical oxidation, carbamazepine was found to undergo ring contraction and amide bond cleavage, which parallels the oxidative metabolism observed for this drug in leucocytes. The mechanistic information of these redox reactions revealed by EC/DESI-MS would be of value in nitroso-proteome research and carbohydrate/drug metabolic studies. PMID:26242804

  4. Online Investigation of Aqueous-Phase Electrochemical Reactions by Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Lu, Mei; Liu, Yong; Helmy, Roy; Martin, Gary E.; Dewald, Howard D.; Chen, Hao

    2015-08-01

    Electrochemistry (EC) combined with mass spectrometry (MS) is a powerful tool for elucidation of electrochemical reaction mechanisms. However, direct online analysis of electrochemical reaction in aqueous phase was rarely explored. This paper presents the online investigation of several electrochemical reactions with biological relevance in the aqueous phase, such as nitrosothiol reduction, carbohydrate oxidation, and carbamazepine oxidation using desorption electrospray ionization mass spectrometry (DESI-MS). It was found that electroreduction of nitrosothiols [e.g., nitrosylated insulin B (13-23)] leads to free thiols by loss of NO, as confirmed by online MS analysis for the first time. The characteristic mass shift of 29 Da and the reduced intensity provide a quick way to identify nitrosylated species. Equally importantly, upon collision-induced dissociation (CID), the reduced peptide ion produces more fragment ions than its nitrosylated precursor ion (presumably the backbone fragmentation cannot compete with the facile NO loss for the precursor ion), thus facilitating peptide sequencing. In the case of saccharide oxidation, it was found that glucose undergoes electro-oxidation to produce gluconic acid at alkaline pH, but not at neutral and acidic pHs. Such a pH-dependent electrochemical behavior was also observed for disaccharides such as maltose and cellobiose. Upon electrochemical oxidation, carbamazepine was found to undergo ring contraction and amide bond cleavage, which parallels the oxidative metabolism observed for this drug in leucocytes. The mechanistic information of these redox reactions revealed by EC/DESI-MS would be of value in nitroso-proteome research and carbohydrate/drug metabolic studies.

  5. Characterization of the Cathode Electrolyte Interface in Lithium Ion Batteries by Desorption Electrospray Ionization Mass Spectrometry.

    PubMed

    Liu, Yao-Min; G Nicolau, Bruno; Esbenshade, Jennifer L; Gewirth, Andrew A

    2016-07-19

    The solid electrolyte interface (SEI) formed via electrolyte decomposition on the anode of lithium ion batteries is largely responsible for the stable cycling of conventional lithium ion batteries. Similarly, there is a lesser-known analogous layer on the cathode side of a lithium ion battery, termed the cathode electrolyte interface (CEI), whose composition and role are debated. To confirm the existence and composition of the CEI, desorption electrospray ionization mass spectrometry (DESI-MS) is applied to study common lithium ion battery cathodes. We observe CEI formation on the LiMn2O4 cathode material after cycling between 3.5 and 4.5 V vs Li/Li(+) in electrolyte solution containing 1 M LiPF6 or LiClO4 in 1:1 (v/v) ethylene carbonate (EC) and dimethyl carbonate (DMC). Intact poly(ethylene glycol) dimethyl ether is identified as the electrolyte degradation product on the cathode surface by the high mass-resolution Orbitrap mass spectrometer. When EC is paired with ethyl methyl carbonate (EMC), poly(ethylene glycol) dimethyl ether, poly(ethylene glycol) ethyl methyl ether, and poly(ethylene glycol) are found on the surface simultaneously. The presence of ethoxy and methoxy end groups indicates both methoxide and ethoxide are produced and involved in the process of oligomerization. Au surfaces cycled under different electrochemical windows as model systems for Li-ion battery anodes are also examined. Interestingly, the identical oligomeric species to those found in the CEI are found on Au surfaces after running five cycles between 2.0 and 0.1 V vs Li/Li(+) in half-cells. These results show that DESI-MS provides intact molecular information on battery electrodes, enabling deeper understanding of the SEI or CEI composition. PMID:27346184

  6. The dissociation kinetics of NO on Rh(111) as studied by temperature programmed static secondary ion mass spectrometry and desorption

    NASA Astrophysics Data System (ADS)

    Borg, H. J.; Reijerse, J. F. C.-J. M.; van Santen, R. A.; Niemantsverdriet, J. W.

    1994-12-01

    Temperature programmed static secondary ion mass spectrometry (TPSSIMS) and temperature programmed desorption (TPD) have been used to study the kinetics of adsorption, dissociation, and desorption of NO on Rh(111). At 100 K, NO adsorption is molecular and proceeds via mobile precursor state kinetics with a high initial sticking probability. SSIMS indicates the presence of two distinct NO adsorption states, indicative of threefold adsorption at low coverage, and occupation of bridge sites at higher coverages. Three characteristic coverage regimes appear with respect to NO dissociation. At low coverages θNO<0.25 ML, NO dissociates completely at temperatures between 275 and 340 K. If we neglect lateral interactions and assume pure first order dissociation kinetics, we find effective values for the activation barrier and preexponential factor of 40±6 kJ/mol and 106±1 s-1 for the dissociation of 0.15-0.20 ML NO. However, if we assume that a NO molecule needs an ensemble of three to four vacant sites in order to dissociate, the preexponential factor and activation energy are ˜1011 s-1 and 65 kJ/mol, in better agreement with transition state theory expectations. The Nads and Oads dissociation products desorb as N2 and O2, respectively, with desorption parameters Edes=118±10 kJ/mol and νdes=1010.1±1.0 s-1 for N2 in the zero coverage limit. At higher coverages, the desorption kinetics of N2 is strongly influenced by the presence of coadsorbed oxygen. In the medium coverage range 0.25<θNO<0.50 ML, part of the NO desorbs molecularly, with an estimated desorption barrier of 113±10 kJ/mol and a preexponential of 1013.5±1.0 s-1. Dissociation of NO becomes progressively inhibited due to site blocking, the onset shifting from 275 K at 0.25 ML to 400 K, coinciding with the NO desorption temperature, at a coverage of 0.50 ML. The accumulation of nitrogen and oxygen atoms on the highly covered surface causes a destabilization of the nitrogen atoms, which results in an

  7. Merits of online electrochemistry liquid sample desorption electrospray ionization mass spectrometry (EC/LS DESI MS).

    PubMed

    Looi, Wen Donq; Brown, Blake; Chamand, Laura; Brajter-Toth, Anna

    2016-03-01

    A new online electrochemistry/liquid sample desorption electrospray ionization mass spectrometry (EC/LS DESI MS) system with a simple electrochemical thin-layer flow-through cell was developed and tested using N,N-dimethyl-p-phenylenediamine (DMPA) as a model probe. Although oxidation of DMPA is observed as a result of ionization of LS in positive ion mode LS DESI, application of voltage to the online electrochemical (EC) cell in EC/LS DESI MS increases yields of oxidation products. An advantage of LS DESI MS is its sensitivity in aqueous electrolyte solutions, which improves efficiency of electrochemical reactions in EC/LS DESI MS. In highly conductive low pH aqueous buffer solutions, oxidation efficiency is close to 100 %. EC/ESI MS typically requires mixed aqueous/organic solvents and low electrolyte concentrations for efficient ionization in MS, limiting efficiency of electrochemistry online with MS. Independently, the results verify higher electrochemical oxidation efficiency during positive mode ESI than during LS DESI. Graphical abstract Detection of DMPA oxidation in online electrochemical cell with EC/LS DESI MS. PMID:26886744

  8. Identification of organic pigments in automotive coatings using laser desorption mass spectrometry.

    PubMed

    Stachura, Sylwia; Desiderio, Vincent J; Allison, John

    2007-05-01

    When one looks at an automotive coating, one sees color due to pigments. Modern organic pigments, with high molar absorptivities, may be only minor components of the mixture. Laser desorption mass spectrometry (LDMS) has been shown to be a useful tool for the analysis of colorants such as pen ink dyes. Here, LDMS is used to determine its utility for the identification of pigments, in simple media and in more complex paints. Small paint chips can be introduced into the LDMS instrument, and when an ultraviolet laser is focused on a portion of a chip, ions representative of the pigment(s) are selectively formed. Some pigments such as quinacridones and copper phthalocyanine are very stable and are desorbed and ionized intact. In contrast, benzimidazolones, which contain some single-skeletal bonds, form fragment ions. This method proves to be sensitive and convenient, as no sample preparation is required. The presence of inorganic pigments in addition to modern organic pigments can be determined, and pigments can be directly identified in actual automotive paint chip samples. PMID:17456087

  9. Selective detection of homocysteine by laser desorption/ionization mass spectrometry.

    PubMed

    Su, Chih-Lin; Tseng, Wei-Lung

    2006-01-01

    This article describes the use of 2,3-naphthalenedicarboxaldehyde (NDA) as a selective probe for the determination of homocysteine (HCys) via fluorescence measurement and laser desorption/ionization mass spectrometry (LDI-MS). The derivatives of three aminothiols-HCys, glutathione (GSH), and gamma-glutamylcysteine (gamma-Glu-Cys)-with NDA under alkaline conditions possess different fluorescence emission characteristics, which allow us to identify them from amines, amino acids, and thiols. By selecting appropriate pH and excitation wavelengths, the limits of detection (LODs) at a signal-to-noise ratio of 3 were 5.2, 1.4 and 16 nM for HCys, GSH and gamma-Glu-Cys, respectively. Additionally, strong UV absorption of the NDA-HCys derivative was further observed at 331 nm; it could be directly detected by LDI-MS with a 337-nm nitrogen laser. Selective detection of HCys has been achieved by conducting the LDI-MS of the NDA-HCys derivative, which was found at m/z 406.9. The lowest detectable concentration of the NDA-HCys derivative in this approach was 500 nM. Quantitative determination of HCys in urine samples was accomplished by LDI-MS. Also, a calibration curve was created from plasma samples spiked with standard HCys (20-100 microM). The experimental results suggest that our proposed methods have great potential in clinical diagnosis and metabolomics application. PMID:17044125

  10. Imaging Nicotine in Rat Brain Tissue by Use of Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Thomas, Mathew; Carson, James P.; Smith, Jordan N.; Timchalk, Charles; Laskin, Julia

    2013-01-15

    Imaging mass spectrometry offers simultaneous detection of drugs, drug metabolites and endogenous substances in a single experiment. This is important when evaluating effects of a drug on a complex organ system such as the brain, where there is a need to understand how regional drug distribution impacts function. Nicotine is an addictive drug and its action in the brain is of high interest. Here we use nanospray desorption electrospray ionization, nano-DESI, imaging to discover the localization of nicotine in rat brain tissue after in vivo administration of nicotine. Nano-DESI is a new ambient technique that enables spatially-resolved analysis of tissue samples without special sample pretreatment. We demonstrate high sensitivity of nano-DESI imaging that enables detection of only 0.7 fmole nicotine per pixel in the complex brain matrix. Furthermore, by adding deuterated nicotine to the solvent, we examined how matrix effects, ion suppression, and normalization affect the observed nicotine distribution. Finally, we provide preliminary results suggesting that nicotine localizes to the hippocampal substructure called dentate gyrus.

  11. Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

    PubMed Central

    Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

    2010-01-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. Four APCI reagent systems were tested: the traditionally used mixture of methanol and water, neat benzene, neat carbon disulfide, and nitrogen gas (no liquid reagent). The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar amount of fragmentation was observed for these reagents. When the experiment was performed without a liquid reagent(nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to form stable molecular ions. PMID:21472571

  12. Distribution of terfenadine and its metabolites in locusts studied by desorption electrospray ionization mass spectrometry imaging.

    PubMed

    Olsen, Line Rørbæk; Hansen, Steen Honoré; Janfelt, Christian

    2015-03-01

    Desorption electrospray ionization (DESI) mass spectrometry (MS) imaging was used to image locusts dosed with the antihistamine drug terfenadine. The study was conducted in order to elucidate a relatively high elimination rate of terfenadine from the locust hemolymph. In this one of the few MS imaging studies on insects, a method for cryosectioning of whole locusts was developed, and the distributions of a number of endogenous compounds are reported, including betaine and a number of amino acids and phospholipids. Terfenadine was detected in the stomach region and the intestine walls, whereas three different metabolites-terfenadine acid (fexofenadine), terfenadine glucoside, and terfenadine phosphate-were detected in significantly smaller amounts and only in the unexcreted feces in the lower part of the intestine. The use of MS/MS imaging was necessary in order to detect the metabolites. With use of DESI-MS imaging, no colocalization of the drug and the metabolites was observed, suggesting a very rapid excretion of metabolites into the feces. Additional liquid chromatography-MS investigations were performed on hemolymph and feces and showed some abundance of terfenadine and the three metabolites, although at low levels, in both the hemolymph and the feces. PMID:25404166

  13. Application of desorption electrospray ionization mass spectrometry imaging in breast cancer margin analysis

    PubMed Central

    Calligaris, David; Caragacianu, Diana; Liu, Xiaohui; Norton, Isaiah; Thompson, Christopher J.; Richardson, Andrea L.; Golshan, Mehra; Easterling, Michael L.; Santagata, Sandro; Dillon, Deborah A.; Jolesz, Ferenc A.; Agar, Nathalie Y. R.

    2014-01-01

    Distinguishing tumor from normal glandular breast tissue is an important step in breast-conserving surgery. Because this distinction can be challenging in the operative setting, up to 40% of patients require an additional operation when traditional approaches are used. Here, we present a proof-of-concept study to determine the feasibility of using desorption electrospray ionization mass spectrometry imaging (DESI-MSI) for identifying and differentiating tumor from normal breast tissue. We show that tumor margins can be identified using the spatial distributions and varying intensities of different lipids. Several fatty acids, including oleic acid, were more abundant in the cancerous tissue than in normal tissues. The cancer margins delineated by the molecular images from DESI-MSI were consistent with those margins obtained from histological staining. Our findings prove the feasibility of classifying cancerous and normal breast tissues using ambient ionization MSI. The results suggest that an MS-based method could be developed for the rapid intraoperative detection of residual cancer tissue during breast-conserving surgery. PMID:25246570

  14. Metabolic Profiling Directly from the Petri Dish Using Nanospray Desorption Electrospray Ionization Imaging Mass Spectrometry

    SciTech Connect

    Watrous, Jeramie D.; Roach, Patrick J.; Heath, Brandi S.; Alexandrov, Theodore; Laskin, Julia; Dorrestein, Pieter C.

    2013-11-05

    Understanding molecular interaction pathways in complex biological systems constitutes a treasure trove of knowledge that might facilitate the specific, chemical manipulation of the countless microbiological systems that occur throughout our world. However, there is a lack of methodologies that allow the direct investigation of chemical gradients and interactions in living biological systems, in real time. Here, we report the use of nanospray desorption electrospray ionization (nanoDESI) imaging mass spectrometry for in vivo metabolic profiling of living bacterial colonies directly from the Petri dish with absolutely no sample preparation needed. Using this technique, we investigated single colonies of Shewanella oneidensis MR-1, Bacillus subtilis 3610, and Streptomyces coelicolor A3(2) as well as a mixed biofilm of S. oneidensis MR-1 and B. subtilis 3610. Data from B. subtilis 3610 and S. coelicolor A3(2) provided a means of validation for the method while data from S. oneidensis MR-1 and the mixed biofilm showed a wide range of compounds that this bacterium uses for the dissimilatory reduction of extracellular metal oxides, including riboflavin, iron-bound heme and heme biosynthetic intermediates, and the siderophore putrebactin.

  15. Sequence analysis of chitooligosaccharides by matrix-assisted laser desorption ionization postsource decay mass spectrometry.

    PubMed

    Bahrke, Sven; Einarsson, Jon M; Gislason, Johannes; Haebel, Sophie; Letzel, Matthias C; Peter-Katalinić, Jasna; Peter, Martin G

    2002-01-01

    Chitin/chitosan oligosaccharides composed of 2-acetamido-2-deoxy-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-D-glucopyranose (GlcN) were prepared by chemical degradation of chitin or chitosan and separated by gel permeation chromatography. Oligosaccharides obtained after enzymatic hydrolysis of chitosan [F(A) 0.19] with a fungal chitinase were derivatized by reductive amination with 2-aminoacridone and sequenced by matrix-assisted laser desorption ionization time-of-flight postsource decay (PSD) mass spectrometry (MS). The sequence of a trimer, D1A2, was established as D-A-A. The composition of a hexamer D3A3 was ca. 65% D-A-D-D-A-A and 35% D-D-A-D-A-A. The PSD MS of a nonamer D5A4-amac revealed four isobaric species D-X-Y-D-X-Y-D-A-A, where A is GlcNAc, D is GlcN, and X and Y (X not equal Y) are mutually either D or A. This structure motif was also observed in a dodecamer D7A5 which was composed of eight isobaric sequences of the general formula (D-X-Y)(3)-D-A-A. PMID:12099813

  16. Laser-Induced Acoustic Desorption/Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Gao, Jinshan; Borton, David J.; Owen, Benjamin C.; Jin, Zhicheng; Hurt, Matt; Amundson, Lucas M.; Madden, Jeremy T.; Qian, Kuangnan; Kenttämaa, Hilkka I.

    2011-03-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a commercial linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. From the four APCI reagent systems tested, neat carbon disulfide provided the best results. The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar but minor amount of fragmentation was observed for these two reagents. When the experiment was performed without a liquid reagent (nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to predominantly form stable molecular ions.

  17. Thermal desorption gas chromatography with mass spectrometry study of outgassing from polymethacrylimide foam (Rohacell®).

    PubMed

    Carrasco-Correa, Enrique J; Herrero-Martínez, José M; Consuegra, Lina; Ramis-Ramos, Guillermo; Sanz, Rafael Mata; Martínez, Benito Gimeno; Esbert, Vicente E Boria; García-Baquero, David Raboso

    2015-09-01

    Polymethacrylimide foams are used as light structural materials in outer-space devices; however, the foam closed cells contain volatile compounds that are outgassed even at low temperatures. These compounds ignite as plasmas under outer-space radiation and the intense radio-frequency fields used in communications. Since plasmas may cause spacecraft fatal events, the conditions in which they are ignited should be investigated. Therefore, qualitative and quantitative knowledge about polymethacrylimide foam outgassing should be established. Using thermogravimetric analysis, weight losses reached 3% at ca. 200°C. Thermal desorption gas chromatography with mass spectrometry detection was used to study the offgassed compounds. Using successive 4 min heating cycles at 125°C, each one corresponding to an injection, significant amounts of nitrogen (25.3%), water (2.6%), isobutylene (11.3%), tert-butanol (2.9%), 1-propanol (11.9%), hexane (25.3%), propyl methacrylate (1.4%), higher hydrocarbons (11.3%), fatty acids (2.2%) and their esters (1.3%), and other compounds were outgassed. Other compounds were observed during the main stage of thermal destruction (220-280°C). A similar study at 175°C revealed the extreme difficulty in fully outgassing polar compounds from polymethacrylimide foams by baking and showed the different compositions of the offgassed atmosphere that can be expected in the long term. PMID:26106018

  18. Tracing origins of complex pharmaceutical preparations using surface desorption atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Zhang, Xinglei; Jia, Bin; Huang, Keke; Hu, Bin; Chen, Rong; Chen, Huanwen

    2010-10-01

    A novel strategy to trace the origins of commercial pharmaceutical products has been developed based on the direct chemical profiling of the pharmaceutical products by surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS). Besides the unambiguous identification of active drug components, various compounds present in the matrixes are simultaneously detected without sample pretreatment, providing valuable information for drug quality control and origin differentiation. Four sources of commercial amoxicillin products made by different manufacturers have been successfully differentiated. This strategy has been extended to secerning six sources of Liuwei Dihuang Teapills, which are herbal medicine preparations with extremely complex matrixes. The photolysis status of chemical drug products and the inferior natural herd medicine products prepared with different processes (e.g., extra heating) were also screened using the method reported here. The limit of detection achieved in the MS/MS experiments was estimated to be 1 ng/g for amoxicillin inside the capsule product. Our experimental data demonstrate that DAPCI-MS is a useful tool for rapid pharmaceutical analysis, showing promising perspectives for tracking the entire pharmaceutical supply chain to prevent counterfeit intrusions. PMID:20809628

  19. Matrix assisted laser desorption ionization mass spectrometry imaging identifies markers of ageing and osteoarthritic cartilage

    PubMed Central

    2014-01-01

    Introduction Cartilage protein distribution and the changes that occur in cartilage ageing and disease are essential in understanding the process of cartilage ageing and age related diseases such as osteoarthritis. The aim of this study was to investigate the peptide profiles in ageing and osteoarthritic (OA) cartilage sections using matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI). Methods The distribution of proteins in young, old and OA equine cartilage was compared following tryptic digestion of cartilage slices and MALDI-MSI undertaken with a MALDI SYNAPT™ HDMS system. Protein identification was undertaken using database searches following multivariate analysis. Peptide intensity differences between young, ageing and OA cartilage were imaged with Biomap software. Analysis of aggrecanase specific cleavage patterns of a crude cartilage proteoglycan extract were used to validate some of the differences in peptide intensity identified. Immunohistochemistry studies validated the differences in protein abundance. Results Young, old and OA equine cartilage was discriminated based on their peptide signature using discriminant analysis. Proteins including aggrecan core protein, fibromodulin, and cartilage oligomeric matrix protein were identified and localised. Fibronectin peptides displayed a stronger intensity in OA cartilage. Age-specific protein markers for collectin-43 and cartilage oligomeric matrix protein were identified. In addition potential fibromodulin and biglycan peptides targeted for degradation in OA were detected. Conclusions MALDI-MSI provided a novel platform to study cartilage ageing and disease enabling age and disease specific peptides in cartilage to be elucidated and spatially resolved. PMID:24886698

  20. Chemical Analysis of Organic Aerosols Using Reactive Nanospray Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Laskin, A.; Laskin, J.; Nizkorodov, S.

    2013-12-01

    Nanospray Desorption Electrospray Ionization (nano-DESI) technique integrated with high resolution mass spectrometry (HR-MS) enables molecular level analysis of organic aerosol (OA) samples. In nano-DESI, analyte is desorbed into a small volume solvent bridge formed between two capillaries positioned in contact with analyte and enables fast and efficient characterization of OA collected on substrates without sample preparation. We report applications of the nano-DESI/HR-MS approach in a number of our recent studies focused on molecular identification of organic compounds in laboratory and in field collected OA samples. Reactive nano-DESI approach where selected reagent is added to the solvent is used for examining the presence of individual species containing specific functional groups and for their quantification within complex mixtures of OA. Specifically, we use the Girard's reagent T (GT) to probe and quantify carbonyl compounds in the SOA mixtures. We estimate for the first time the amounts of dimers and trimers in the SOA mixtures. We found that the most abundant dimer in limonene/O3 SOA was detected at the ˜0.5 pg level and the total amount of dimers and trimers in the analyzed sample was ˜11 pg. Understanding of the OA composition at the molecular level allowed us to identify key aging reactions, including the transformation of carbonyls to imines and carbonyl-imine oligomerization, that may contribute to the formation of brown carbon in the atmosphere.

  1. Rapid detection of terbufos in stomach contents using desorption electrospray ionization mass spectrometry.

    PubMed

    Wilson, Christina R; Mulligan, Christopher C; Strueh, Kurt D; Stevenson, Gregory W; Hooser, Stephen B

    2014-03-26

    Desorption electrospray ionization mass spectrometry (DESI-MS) is an emerging analytical technique that permits the rapid and direct analysis of biological or environmental samples under ambient conditions. Highlighting the versatility of this technique, DESI-MS has been used for the rapid detection of illicit drugs, chemical warfare agents, agricultural chemicals, and pharmaceuticals from a variety of sample matrices. In diagnostic veterinary toxicology, analyzing samples using traditional analytical instrumentation typically includes extensive sample extraction procedures, which can be time consuming and labor intensive. Therefore, efforts to expedite sample analyses are a constant goal for diagnostic toxicology laboratories. In the current report, DESI-MS was used to directly analyze stomach contents from a dog exposed to the organophosphate insecticide terbufos. The total DESI-MS analysis time required to confirm the presence of terbufos and diagnose organophosphate poisoning in this case was approximately 5 min. This highlights the potential of this analytical technique in the field of veterinary toxicology for the rapid diagnosis and detection of toxicants in biological samples. PMID:24670950

  2. Rapid determination of nicotine in urine by direct thermal desorption ion trap mass spectrometry

    SciTech Connect

    Wise, M.B.; Ilgner, R.H.; Guerin, M.R.

    1990-01-01

    The measurement of nicotine and cotinine in physiological fluids (urine, blood serum, and saliva) is widely used as a means of assessing human exposure to environmental tobacco smoke (ETS). Although numerous analytical methods exist for these measurements, they generally involve extensive sample preparation which increases cost and decreases sample throughput. We report the use of thermal desorption directly into an ion trap mass spectrometer (ITMS) for the rapid determination of nicotine and cotinine in urine. A 1{mu}L aliquot of urine is injected into a specially designed inlet and flash vaporized directly into an ITMS through an open-split capillary restrictor interface. Isobutane chemical ionization is used to generate (M+H){sup +} ions of the analytes and collision induced dissociation is used to generate characteristic fragment ions which are used to confirm their identity. Quantification is achieved by integrating the ion current for the characteristic ions and comparing with an external working curve. Detection limits are approximately 50 pg per analyte and the sample turnaround time is approximately 3 minutes without the need for extensive sample preparation. 12 refs., 5 figs.

  3. Direct analysis of ethylenediaminetetraacetic acid (EDTA) on concrete by reactive-desorption electrospray ionization mass spectrometry.

    PubMed

    Lebeau, D; Reiller, P E; Lamouroux, C

    2015-01-01

    Analysis of organic ligands such as ethylenediaminetetraacetic acid (EDTA) is today an important challenge due to their ability to increase the mobility of radionuclides and metals. Reactive desorption electrospray ionization mass spectrometry (reactive-DESI-MS) was used for direct analysis of EDTA on concrete samples. EDTA forms complexes and those with Fe(III) ions are among the most thermodynamically favored. This complexing capacity was used to improve the specific detection of EDTA directly on a concrete matrix by doping the solvent spray of DESI with a solution of FeCl3 to selectively create the complex between EDTA and Fe(III). Thus, EDTA sensitivity was largely improved by two orders of magnitude with reactive-DESI-MS experiments thanks to the specific detection of EDTA as a [EDTA-4H+Fe(III)](-) complex. The proof of principle that reactive DESI can be applied to concrete samples to detect EDTA has been demonstrated. Its capacity for semi-quantitative determination and localization of EDTA under ambient conditions and with very little sample preparation, minimizing sample manipulations and solvent volumes, two important conditions for the development of new methodologies in the field of analytical chemistry, has been shown. PMID:25476391

  4. Metabolic profiling directly from the Petri dish using nanospray desorption electrospray ionization imaging mass spectrometry.

    PubMed

    Watrous, Jeramie; Roach, Patrick; Heath, Brandi; Alexandrov, Theodore; Laskin, Julia; Dorrestein, Pieter C

    2013-11-01

    Understanding molecular interaction pathways in complex biological systems constitutes a treasure trove of knowledge that might facilitate the specific, chemical manipulation of the countless microbiological systems that occur throughout our world. However, there is a lack of methodologies that allow the direct investigation of chemical gradients and interactions in living biological systems, in real time. Here, we report the use of nanospray desorption electrospray ionization (nanoDESI) imaging mass spectrometry for in vivo metabolic profiling of living bacterial colonies directly from the Petri dish with absolutely no sample preparation needed. Using this technique, we investigated single colonies of Shewanella oneidensis MR-1, Bacillus subtilis 3610, and Streptomyces coelicolor A3(2) as well as a mixed biofilm of S. oneidensis MR-1 and B. subtilis 3610. Data from B. subtilis 3610 and S. coelicolor A3(2) provided a means of validation for the method while data from S. oneidensis MR-1 and the mixed biofilm showed a wide range of compounds that this bacterium uses for the dissimilatory reduction of extracellular metal oxides, including riboflavin, iron-bound heme and heme biosynthetic intermediates, and the siderophore putrebactin. PMID:24047514

  5. Beer fingerprinting by Matrix-Assisted Laser Desorption-Ionisation-Time of Flight Mass Spectrometry.

    PubMed

    Šedo, Ondrej; Márová, Ivana; Zdráhal, Zbyněk

    2012-11-15

    A method allowing parallel fingerprinting of proteins and maltooligosaccharides directly from untreated beer samples is presented. These two classes of compounds were detected by Matrix-Assisted Laser Desorption-Ionisation-Time of Flight-Mass Spectrometry (MALDI-TOF-MS) analysis of beer mixed with 2,5-dihydroxybenzoic acid solution. The maltooligosaccharide profiles acquired from the MALDI sample spot center were not found characteristic for beers of different source and technology. On the other hand, according to profiles containing protein signals acquired from crystals formed on the border of the MALDI sample spot, we were able to distinguish beer samples of the same brand produced by different breweries. The discriminatory abilities of the method were further examined on a set of 17 lager beers, where the fingerprints containing protein signals enabled resolution of majority of examined brands. We propose MALDI-TOF-MS profiling as a rapid tool for beer brewing technology process monitoring, quality control, and determination of beer authenticity. PMID:22868116

  6. Field desorption mass spectroscopy monitoring of changes in hydrocarbon type composition during petroleum biodegradation

    SciTech Connect

    Huesemann, M.H.

    1995-12-31

    A comprehensive petroleum hydrocarbon characterization procedure involving group type separation, boiling point distribution, and hydrocarbon typing by field desorption mass spectroscopy (FDMS) has been developed to quantify changes in hydrocarbon type composition during bioremediation of petroleum-contaminated soils. FDMS is able to quantify the concentration of hundreds of specific hydrocarbon types based on their respective hydrogen deficiency (z-number) and molecular weight (carbon number). Analytical results from two bioremediation experiments involving soil contaminated with crude oil and motor oil indicate that alkanes and two-ring saturates (naphthenes) were readily biodegradable. In addition, low-molecular-weight hydrocarbons generally were biodegraded to a larger extent than those of high molecular weight. More importantly, it was found that the extent of biodegradation of specific hydrocarbon types was comparable between treatments and appeared to be unaffected by the petroleum contaminant source, soil type, or experimental conditions. It was therefore concluded that in these studies the extent of total petroleum hydrocarbon (TPH) biodegradation is primarily affected by the molecular composition of the petroleum hydrocarbons present in the contaminated soil.

  7. Direct detection of chloramphenicol in honey by neutral desorption-extractive electrospray ionization mass spectrometry.

    PubMed

    Huang, X Y; Fang, X W; Zhang, X; Dai, X M; Guo, X L; Chen, H W; Luo, L P

    2014-11-01

    Herein, we constructed a platform of neutral desorption-extractive electrospray ionization mass spectrometry (ND-EESI-MS) for direct and rapid detection of chloramphenicol (CAP) in honey samples diluted with methanol. Under the optimized working conditions, the quantitative information of CAP residues was acquired effectively by EESI-Ion Trap MS (n) . Using heated methanol-N2 as spray reagent, we reduced the limit of determination (LOD) from 73.3 ng/mL to 0.3 ng/mL, and the CAP detection is linear in the range of 1-5000 ng/mL (R = 0.9947). For the honey samples with CAP of 10, 100, and 1000 ng/mL, the recoveries were 133.0, 80.6, and 101.1%, and the relative standard deviations were 5.96, 8.82, and 8.71%, respectively. The reproducibility assays showed the stability of this method. Therefore, this ND-EESI-MS method is powerful for direct, rapid, and quantitative CAP analysis in honey samples with high sensitivity, precision, and specificity. PMID:25277102

  8. Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

    PubMed

    Bibi, Aisha; Ju, Huangxian

    2016-04-01

    A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27041659

  9. Leidenfrost Phenomenon-assisted Thermal Desorption (LPTD) and Its Application to Open Ion Sources at Atmospheric Pressure Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Saha, Subhrakanti; Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

    2013-03-01

    This work describes the development and application of a new thermal desorption technique that makes use of the Leidenfrost phenomenon in open ion sources at atmospheric pressure for direct mass spectrometric detection of ultratrace levels of illicit, therapeutic, and stimulant drugs, toxicants, and peptides (molecular weight above 1 kDa) in their unaltered state from complex real world samples without or with minor sample pretreatment. A low temperature dielectric barrier discharge ion source was used throughout the experiments and the analytical figures of merit of this technique were investigated. Further, this desorption technique coupled with other ionization sources such as electrospray ionization (ESI) and dc corona discharge atmospheric pressure chemical ionization (APCI) in open atmosphere was also investigated. The use of the high-resolution `Exactive Orbitrap' mass spectrometer provided unambiguous identification of trace levels of the targeted compounds from complex mixtures and background noise; the limits of detection for various small organic molecules and peptides treated with this technique were at the level of parts per trillion and 10-9 M, respectively. The high sensitivity of the present technique is attributed to the spontaneous enrichment of analyte molecules during the slow evaporation of the solvent, as well as to the sequential desorption of molecules from complex mixtures based on their volatilities. This newly developed desorption technique is simple and fast, while molecular ions are observed as the major ions.

  10. Leidenfrost phenomenon-assisted thermal desorption (LPTD) and its application to open ion sources at atmospheric pressure mass spectrometry.

    PubMed

    Saha, Subhrakanti; Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

    2013-03-01

    This work describes the development and application of a new thermal desorption technique that makes use of the Leidenfrost phenomenon in open ion sources at atmospheric pressure for direct mass spectrometric detection of ultratrace levels of illicit, therapeutic, and stimulant drugs, toxicants, and peptides (molecular weight above 1 kDa) in their unaltered state from complex real world samples without or with minor sample pretreatment. A low temperature dielectric barrier discharge ion source was used throughout the experiments and the analytical figures of merit of this technique were investigated. Further, this desorption technique coupled with other ionization sources such as electrospray ionization (ESI) and dc corona discharge atmospheric pressure chemical ionization (APCI) in open atmosphere was also investigated. The use of the high-resolution 'Exactive Orbitrap' mass spectrometer provided unambiguous identification of trace levels of the targeted compounds from complex mixtures and background noise; the limits of detection for various small organic molecules and peptides treated with this technique were at the level of parts per trillion and 10(-9) M, respectively. The high sensitivity of the present technique is attributed to the spontaneous enrichment of analyte molecules during the slow evaporation of the solvent, as well as to the sequential desorption of molecules from complex mixtures based on their volatilities. This newly developed desorption technique is simple and fast, while molecular ions are observed as the major ions. PMID:23423791

  11. Enhanced capabilities for imaging gangliosides in murine brain with matrix-assisted laser desorption/ionization and desorption electrospray ionization mass spectrometry coupled to ion mobility separation.

    PubMed

    Škrášková, Karolina; Claude, Emmanuelle; Jones, Emrys A; Towers, Mark; Ellis, Shane R; Heeren, Ron M A

    2016-07-15

    The increased interest in lipidomics calls for improved yet simplified methods of lipid analysis. Over the past two decades, mass spectrometry imaging (MSI) has been established as a powerful technique for the analysis of molecular distribution of a variety of compounds across tissue surfaces. Matrix-assisted laser desorption/ionization (MALDI) MSI is widely used to study the spatial distribution of common lipids. However, a thorough sample preparation and necessity of vacuum for efficient ionization might hamper its use for high-throughput lipid analysis. Desorption electrospray ionization (DESI) is a relatively young MS technique. In DESI, ionization of molecules occurs under ambient conditions, which alleviates sample preparation. Moreover, DESI does not require the application of an external matrix, making the detection of low mass species more feasible due to the lack of chemical matrix background. However, irrespective of the ionization method, the final information obtained during an MSI experiment is very complex and its analysis becomes challenging. It was shown that coupling MSI to ion mobility separation (IMS) simplifies imaging data interpretation. Here we employed DESI and MALDI MSI for a lipidomic analysis of the murine brain using the same IMS-enabled instrument. We report for the first time on the DESI IMS-MSI of multiply sialylated ganglioside species, as well as their acetylated versions, which we detected directly from the murine brain tissue. We show that poly-sialylated gangliosides can be imaged as multiply charged ions using DESI, while they are clearly separated from the rest of the lipid classes based on their charge state using ion mobility. This represents a major improvement in MSI of intact fragile lipid species. We additionally show that complementary lipid information is reached under particular conditions when DESI is compared to MALDI MSI. PMID:26922843

  12. Qualitative analysis of seized cocaine samples using desorption electrospray ionization- mass spectrometry (DESI-MS).

    PubMed

    Stojanovska, Natasha; Tahtouh, Mark; Kelly, Tamsin; Beavis, Alison; Fu, Shanlin

    2015-05-01

    Desorption electrospray ionization - mass spectrometry (DESI-MS) is a useful technique for the qualitative analysis of compounds found in seized drug material. In this study, DESI-MS was utilized in the screening analysis of illicit cocaine samples. The technique was also applied to the geographical origin determination of these samples. The limit of detection was determined to be 24.3 µg (or 3.47 µg/mm(2) ) and the analysis time was less than 1 minute per sample. The intra-day and inter-day precision for the detection of cocaine was 11 % and 42 %, respectively; therefore the quantitative data provided by DESI-MS was limited in its use for accurate determination of cocaine concentration in a sample. Using the quadrupole time-of-flight (QTOF) mass spectrometer, the presence of cocaine and impurities detected were confirmed by accurate tandem MS data. The qualitative chemical profiles obtained using DESI-MS were compared to two popular analysis techniques, GC-MS and LC-MS. The effects of a range of adulterants including caffeine, procaine, levamisole, lignocaine, paracetamol, and atropine on the detectability of cocaine were also investigated. It was found that the addition of these adulterants in a cocaine sample did not prevent the detection of the analyte itself (there was slight enhancement in some samples), which was useful in drug detection. The detection of truxillines in the seized samples by DESI-MS aided in the preliminary determination of geographical origin, i.e., Bolivian, Peruvian or Colombian leaf origin. The application of DESI-MS to the qualitative analysis and screening of seized cocaine samples demonstrates the potential and applicability of the technique to the fast chemical profiling of illicit samples. PMID:24943809

  13. Mapping Lipid Alterations in Traumatically Injured Rat Spinal Cord by Desorption Electrospray Ionization Imaging Mass Spectrometry

    PubMed Central

    Girod, Marion; Shi, Yunzhou; Cheng, Ji-Xin; Cooks, R. Graham

    2010-01-01

    Desorption electrospray ionization (DESI) mass spectrometry is used in an imaging mode to interrogate the lipid profiles of 15 µm thin tissues cross sections of injured rat spinal cord and normal healthy tissue. Increased relative intensities of fatty acids, diacylglycerols and lysolipids (between +120% and +240%) as well as a small decrease in intensities of lipids (−30%) were visualized in the lesion epi-center and adjacent areas after spinal cord injury. This indicates the hydrolysis of lipids during the demyelination process due to activation of phospholipase A2 enzyme. In addition, signals corresponding to oxidative degradation products, such as prostaglandin and hydroxyeicosatetraenoic acid, exhibited increased signal intensity by a factor of two in the negative ion mode in lesions relative to the normal healthy tissue. Analysis of malondialdehyde, a product of lipid peroxidation and marker of oxidative stress, was accomplished in the ambient environment using reactive DESI mass spectrometry imaging. This was achieved by electrospraying reagent solution containing dinitrophenylhydrazine as high velocity charged droplets onto the tissue section. The hydrazine reacts selectively and rapidly with the carbonyl groups of malondialdehyde and signal intensity of twice the intensity was detected in the lesions compared to healthy spinal cord. With a small amount of tissue sample, DESI-MS imaging provides information on the composition and distribution of specific compounds (limited by the occurrence of isomeric lipids with very similar fragmentation patterns) in lesions after spinal cord injury in comparison with normal healthy tissue allowing identification of the extent of the lesion and its repair. PMID:21142140

  14. Atmospheric pressure glow discharge desorption mass spectrometry for rapid screening of pesticides in food.

    PubMed

    Jecklin, Matthias Conradin; Gamez, Gerardo; Touboul, David; Zenobi, Renato

    2008-09-01

    Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS/MS) is used for the analysis of trace amounts of pesticides in fruit juices and on fruit peel. The APGD source was rebuilt after Andrade et al. (Andrade et al., Anal. Chem. 2008; 80: 2646-2653; 2654-2663) and mounted onto a hybrid quadrupole time-of-flight mass spectrometer. Apple, cranberry, grape and orange juices as well as fruit peel and salad leaves were spiked with aqueous solutions containing trace amounts of the pesticides alachlor, atrazine, carbendazim, carbofuran, dinoseb, isoproturon, metolachlor, metolcarb, propoxur and simazine. Best limits of determination (LODs) of pesticides in the fruit juices were achieved for metolcarb (1 microg/L in apple juice), carbofuran and dinoseb (2 microg/L in apple juice); for the analysis of apple skin best LODs were 10 pg/cm(2) of atrazine, metolcarb and propoxur which corresponds to an estimated concentration of 0.01 microg/kg apple, taking into account the surface area and the weight of the apple. The measured LODs were within or below the allowed maximum residue levels (MRLs) decreed by the European Union (1-500 microg/kg for pesticides in fruit juice and 0.01-5 microg/kg for apple skin). No sample pretreatment (extraction, pre-concentration, chromatographic separation) was necessary to analyze these pesticides by direct desorption/ionization using APGD-MS and to identify them using MS/MS. This makes APGD-MS a powerful high-throughput tool for the investigation of very low amounts of pesticides in fruit juices and on fruit peel/vegetable skin. PMID:18697232

  15. Characterization of Coordination Complexes by Desorption Electrospray Mass Spectrometry with a Capillary Target

    SciTech Connect

    Gary S. Groenewold; Anthony D. Appelhans; Michael E. McIlwain; Garold L. Gresham

    2011-03-01

    Metal coordination complexes were formed directly from liquid surfaces using desorption electrospray ionization (DESI) mass spectrometry. The approach is attractive because it separates complexities of ESI spray droplet formation from delivery of the analyte solution, and thereby gets around difficulty resulting from alteration of the spray process by changes in solution chemistry. Cs+, Ba2+, and La3+ coordination complexes were formed using 18-crown-6 (18c6) and triethylphosphate (TEP) as ligands (L), that had the general formula [Mn+(NO3-)n-1(L)m]+. Formation of singly charged cation complexes was preferred, with charge reduction at the metal site accomplished by attachment of nitrate. Using TEP as a model phosphoryl ligand, alkali metals coordinate with up to three ligands, with Cs+ preferring fewer than Na+. Ba2+ and La3+ are formed as ion pair complexes [Ba(NO3)]+ and [La(NO3)2]+, and both will coordinate with up to four TEP ligands. Using 18c6, Cs+ forms a bis-ligand complex. In contrast, [Ba(NO3)]+ prefers a single 18c6 ligand, while La forms mainly [La(NO3)2(18c6)]+, for which DFT calculations suggested a structure in which the nitrate ligands occupy pseudo-axial positions on opposing sides of the crown. Lower abundances of bis-18c6 complexes were also formed together with doubly charged [La(NO3)(18c6)n]2+ complexes (n = 2 – 4). The results suggest an alternative strategy for probing metal speciation in solution that is less perturbed by the droplet formation and ionization mechanisms operating in conventional electrospray ionization mass spectrometry.

  16. Structural features of lipoarabinomannan from Mycobacterium bovis BCG. Determination of molecular mass by laser desorption mass spectrometry.

    PubMed

    Venisse, A; Berjeaud, J M; Chaurand, P; Gilleron, M; Puzo, G

    1993-06-15

    It was recently shown that mycobacterial lipoarabinomannan (LAM) can be classified into two types (Chatterjee, D., Lowell, K., Rivoire B., McNeil M. R., and Brennan, P. J. (1992) J. Biol. Chem. 267, 6234-6239) according to the presence or absence of mannosyl residues (Manp) located at the nonreducing end of the oligoarabinosyl side chains. These two types of LAM were found in a pathogenic Mycobacterium tuberculosis strain and in an avirulent M. tuberculosis strain, respectively, suggesting that LAM with Manp characterizes virulent and "disease-inducing strains." We now report the structure of the LAM from Mycobacterium bovis Bacille Calmette-Guérin (BCG) strain Pasteur, largely used throughout the world as vaccine against tuberculosis. Using an up-to-date analytical approach, we found that the LAM of M. bovis BCG belongs to the class of LAMs capped with Manp. By means of two-dimensional homonuclear and heteronuclear scalar coupling NMR analysis and methylation data, the sugar spin system assignments were partially established, revealing that the LAM contained two types of terminal Manp and 2-O-linked Manp. From the following four-step process: (i) partial hydrolysis of deacylated LAM (dLAM), (ii) oligosaccharide derivatization with aminobenzoic ethyl ester, (iii) HPLC purification, (iv) FAB/MS-MS analysis; it was shown that the dimannosyl unit alpha-D-Manp-(1-->2)-alpha-D-Manp is the major residue capping the termini of the arabinan of the LAM. In this report, LAM molecular mass determination was established using matrix-assisted UV-laser desorption/ionization mass spectrometry which reveals that the LAM molecular mass is around 17.4 kDa. The similarity of the LAM structures between M. bovis BCG and M. tuberculosis H37Rv is discussed in regard to their function in the immunopathology of mycobacterial infection. PMID:8509380

  17. Matrix-assisted laser-desorption-ionization mass spectrometry of proteins using a free-electron laser

    SciTech Connect

    Cramer, R.; Hillenkamp, F.; Haglund, R.

    1995-12-31

    Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) is one of the most promising techniques for spectral fingerprinting large molecules, such as proteins, oligonucleotides and carbohydrates. In the usual implementation of this technique, the analyte molecule is dissolved in an aromatic liquid matrix material which resonantly absorbs ultraviolet laser light. Resonant absorption by {pi}-{pi}* transitions volatilizes the matrix and initiates subsequent charge transfer to the analyte molecules, which are detected by time-of-flight mass spectrometry. Recent MALDI-MS studies with Er:YAG (2.94 {mu}m) and CO{sub 2}{sup 4} (9.4-10.6 {mu}m) lasers suggest that them is significant unexplored potential for mass spectrometry of macromolecules, including oligonucleotide, in the mid-infrared. Preliminary experiments show that it is possible to capitalize on the rich rovibronic absorption spectrum of virtually all organics to initiate resonant desorption in matrix material over the entire range of pH values. However, the mechanism of charge transfer is particularly problematic for infrared MALDI because of the low photon energy. In this paper, we report the results of MALI-MS studies on small proteins using the Vanderbilt FEL and several matrix materials. Proteins with masses up to roughly 6,000 amu were detected with high resolution in a linear time-of-flight mass spectrometer. By varying the pulse duration using a broadband Pockels cell, we have been able to compare the results of relatively long (5 {mu}s) and short (0.1 {mu}s) irradiation on the desorption and ionization processes. Compared to uv-MALDI spectra of identical analytes obtained with a nitrogen laser (337 nm) in the same time-of-flight spectrometer, the infrared results appear to show that the desorption and ionization process goes on over a somewhat longer time scale.

  18. Analysis of colorectal adenocarcinoma tissue by desorption electrospray ionization mass spectrometric imaging.

    PubMed

    Gerbig, Stefanie; Golf, Ottmar; Balog, Julia; Denes, Julia; Baranyai, Zsolt; Zarand, Attila; Raso, Erzsebet; Timar, Jozsef; Takats, Zoltan

    2012-06-01

    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

  19. Ionic liquids as matrices in microfluidic sample deposition for high-mass matrix- assisted laser desorption/ionization mass spectrometry.

    PubMed

    Weidmann, Simon; Kemmerling, Simon; Mädler, Stefanie; Stahlberg, Henning; Braun, Thomas; Zenobi, Renato

    2012-01-01

    Sample preparation for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) via a microfluidic deposition device using ionic liquid matrices addresses several problems of standard protocols with crystalline matrices, such as the heterogeneity of sample spots due to the co-crystallization of sample and matrix and the limited capability for high-throughput analysis. Since ionic liquid matrices do not solidify during the measurement, the resulting sample spots are homogeneous. The use of these matrices is also beneficial for automated sample preparation, since crystallization of the matrix is avoided and, thus, no clogging of the spotting device can occur. The applicability of ionic liquids to the analysis of biomolecules with high molecular weights, up to ≈ 1 MDa is shown, as well as a good sensitivity (5 fmol) for recombinant human fibronectin, a protein with a molecular weight of 226 kDa. Microfluidic sample deposition of proteins with high molecular weights will, in the future, allow parallel sample preparation for MALDI-MS and for electron microscopy. PMID:22837434

  20. The Effect of Culture Conditions on Microorganism Identification by Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

    SciTech Connect

    Valentine, Nancy B.; Wunschel, Sharon C.; Wunschel, David S.; Petersen, Catherine E.; Wahl, Karen L.

    2005-01-01

    Abstract Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used to identify bacteria based upon protein signatures. This research shows that while some different proteins are produced by vegetative bacteria when they are cultured in different growth media, positive identification with MALDI-TOF MS is still possible with the protocol established at Pacific Northwest National Laboratory (PNNL)(11). A core set of small proteins remain constant under at least four different culture media conditions including minimal medium -M9, rich media - tryptic soy broth (TSB) or Luria-Bertani (LB) broth and blood agar plates such that analysis of the intact cells by matrix-assisted laser desorption/ionization mass spectrometry allows for consistent identification.

  1. Development of matrix-assisted ultraviolet laser desorption/ionization mass spectrometry for the structural analysis of glycoproteins

    SciTech Connect

    Chevrier, M.R.

    1993-01-01

    This thesis describes the design, construction and characterization of an ultraviolet laser desorption time-of-flight [TOF] mass spectrometer and its subsequent application to glycoprotein structural analysis utilizing matrix-assisted laser desorption/ionization [MALDI] mass spectrometry. At the inception of this work, commercial mass spectrometers utilizing MALDI were not available, and most reports of the phenomena utilized the 266 nm wavelength provided by frequency-quadrupled Nd:YAG lasers. This work involved the design and construction of a high-voltage-extraction linear TOF mass analyzer equipped with a multiple sample inlet system and a 337 manometer, 600 picosecond pulsed nitrogen laser. In MALDI the [open quotes]matrix[close quotes], a strong absorber of a laser wavelength, is co-crystallized with the analyte. The laser photons absorbed by the matrix lead to ionization of the analyte and subsequent desorption from the surface into the gas phase. While nicotinic acid and caffeic acid were reported as effective matrices at 266 and 355 nm, respectively, several other matrices were examined for their efficiency at 337 nm, including [alpha]-cyano-4-hydroxy cinnamic acid and gentisic acid, which proved to be advantageous for glycoconjugate analysis. Glycoproteins, phosphoproteins, nucleic acids, and proteolytic digests were all successfully analyzed using the pulsed nitrogen laser. Analysis of numerous peptides and proteins demonstrated femtomolar sensitivity, mass range in excess of 350 kiloDaltons, mass resolution circa 700, and mass accuracy better than 0.1%. The completed instrument was utilized to analyze glycopeptides for carbohydrate sites and microheterogeneity, by performing MALDI mass spectrometry [MALDI/MS] following enzymatic and chemical reactions. In many cases, unfractionated or partially fractionated mixtures were analyzed directly thereby reducing preparative chromatography.

  2. Rapid Detection of OXA-48-Producing Enterobacteriaceae by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Oviaño, Marina; Barba, Maria José; Fernández, Begoña; Ortega, Adriana; Aracil, Belén; Oteo, Jesús; Campos, José; Bou, Germán

    2016-03-01

    A rapid and sensitive (100%) matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) assay was developed to detect OXA-48-type producers, using 161 previously characterized clinical isolates. Ertapenem was monitored to detect carbapenem resistance, and temocillin was included in the assay as a marker for OXA-48-producers. Structural analysis of temocillin is described. Data are obtained within 60 min. PMID:26677247

  3. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air. PMID:26493981

  4. Gold nanoparticles assisted laser desorption/ionization mass spectrometry and applications: from simple molecules to intact cells.

    PubMed

    Abdelhamid, Hani Nasser; Wu, Hui-Fen

    2016-07-01

    Gold nanoparticles (AuNPs) assisted laser desorption/ionization mass spectrometry (GALDI-MS) provided new horizons and offered many functions for various applications. This review summarized AuNPs applications for analytical, biotechnology and proteomics. AuNPs efficiently absorbed the laser radiation and transferred the energy to the analyte for the desorption/ionization process. The unique features of AuNPs such as large surface area and high absorption coefficient lead not only to high resolution, low interference and low limit of detection, but also offered selective detection for certain species. AuNPs provided an excellent surface for the analysis of several species such as small molecules, biomarkers, proteins and cells (pathogenic bacteria or cancer cells). AuNPs played many roles such as surface for LDI-MS, probe and stationary phase for separation or preconcentration. AuNPs modified various surface chemistry was applied for a wide range of different wavelength. AuNPs severed as a source of Au(+) ions that were suitable for analyte cationisation. Characterization of Au nanoclusters (AuNCs) by mass spectrometry, pros and cons were also highlighted. Graphical Abstract Schematic representation of the analysis by Gold Nanoparticles Assisted Laser Desorption/Ionization Mass Spectrometry (GALDI-MS). PMID:26973236

  5. High-throughput proteomics using matrix-assisted laser desorption/ ionization mass spectrometry.

    PubMed

    Cramer, Rainer; Gobom, Johan; Nordhoff, Eckhard

    2005-06-01

    It has become evident that the mystery of life will not be deciphered just by decoding its blueprint, the genetic code. In the life and biomedical sciences, research efforts are now shifting from pure gene analysis to the analysis of all biomolecules involved in the machinery of life. One area of these postgenomic research fields is proteomics. Although proteomics, which basically encompasses the analysis of proteins, is not a new concept, it is far from being a research field that can rely on routine and large-scale analyses. At the time the term proteomics was coined, a gold-rush mentality was created, promising vast and quick riches (i.e., solutions to the immensely complex questions of life and disease). Predictably, the reality has been quite different. The complexity of proteomes and the wide variations in the abundances and chemical properties of their constituents has rendered the use of systematic analytical approaches only partially successful, and biologically meaningful results have been slow to arrive. However, to learn more about how cells and, hence, life works, it is essential to understand the proteins and their complex interactions in their native environment. This is why proteomics will be an important part of the biomedical sciences for the foreseeable future. Therefore, any advances in providing the tools that make protein analysis a more routine and large-scale business, ideally using automated and rapid analytical procedures, are highly sought after. This review will provide some basics, thoughts and ideas on the exploitation of matrix-assisted laser desorption/ ionization in biological mass spectrometry - one of the most commonly used analytical tools in proteomics - for high-throughput analyses. PMID:16000086

  6. Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry.

    PubMed

    Bügler, Jürgen H; Buchner, Hans; Dallmayer, Anton

    2008-07-01

    Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. PMID:18503526

  7. Dermatophyte Identification Using Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry ▿

    PubMed Central

    Theel, Elitza S.; Hall, Leslie; Mandrekar, Jayawant; Wengenack, Nancy L.

    2011-01-01

    The performance of the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometer (MS) for the identification of dermatophytes from clinical cultures was compared to that of dermatophyte identification using 28S rRNA gene sequencing. The MALDI Biotyper library (MBL; version 3.0) was used alone and in combination with a supplemented library containing an additional 20 dermatophyte spectra (S-MBL). Acquired spectra were interpreted using both the manufacturer-recommended scores (genus, ≥1.7; species, ≥2.0) and adjusted cutoff values established by this study (genus, ≥1.5; species, ≥1.7); identifications required a minimum 10% difference in scores between the top two different organisms to be considered correct. One hundred well-characterized, archived dermatophyte isolates and 71 fresh dermatophyte cultures were evaluated using both libraries and both sets of cutoff criteria. Collectively, the S-MBL significantly outperformed the MBL at both the genus (93% versus 37.4%; P < 0,0001) and species (59.6% versus 20.5%; P < 0.0001) levels when using the adjusted score criteria. Importantly, application of the lowered cutoff values significantly improved genus (P = 0.005)- and species (P < 0.0001)-level identification for the S-MBL, without leading to an increase in misidentifications. MALDI-TOF MS is a cost-effective and rapid alternative to traditional or molecular methods for dermatophyte identification, provided that the reference library is supplemented to sufficiently encompass clinically relevant, intraspecies strain diversity. PMID:21956979

  8. Chemical Analysis of Complex Organic Mixtures Using Reactive Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Laskin, Julia; Eckert, Peter A.; Roach, Patrick J.; Heath, Brandi S.; Nizkorodov, Sergey A.; Laskin, Alexander

    2012-08-21

    Reactive nanospray desorption electrospray ionization (nano-DESI) combined with high-resolution mass spectrometry was utilized for the analysis of secondary organic aerosol produced through ozonolysis of limonene (LSOA). Previous studies showed that LSOA constituents are multifunctional compounds containing aldehyde and ketone groups. In this study, we used the selectivity of the Girard T (GT) reagent towards carbonyl compounds to examine the utility of reactive nano-DESI for the analysis of complex organic mixtures. In these experiments, 1-100 {micro}M GT solution was used as a working solvent for reactive nano-DESI analysis. Abundant products of a single addition of GT to LSOA constituents were observed at GT concentrations in excess of 10 {micro}M. We found that LSOA compounds with 18-20 carbon atoms (dimers) and 27-30 carbon atoms (trimers) react with GT through a simple addition reaction resulting in formation of the carbinolamine derivative. In contrast, reactions of GT with monomeric species result in formation of both the carbinolamine and the hydrazone derivatives. In addition, several monomers did not react with GT on the timescale of our experiment. These molecules were characterized by relatively high values of the double bond equivalent (DBE) and low oxygen content. Furthermore, because addition of a charged GT tag to a neutral molecule eliminates the discrimination against the low proton affinity compounds in the ionization process, reactive nano-DESI analysis enables quantification of individual compounds in the complex mixture. For example, we were able to estimate for the first time the amounts of dimers and trimers in the LSOA mixture. Specifically, we found that the most abundant LSOA dimer was detected at ca. 0.5 pg level and the total amount of dimers and trimers in the analyzed sample was just around 11 pg. Our results indicate that reactive nano-DESI is a valuable approach for examining the presence of specific functional groups and

  9. Chemical analysis of complex organic mixtures using reactive nanospray desorption electrospray ionization mass spectrometry.

    PubMed

    Laskin, Julia; Eckert, Peter A; Roach, Patrick J; Heath, Brandi S; Nizkorodov, Sergey A; Laskin, Alexander

    2012-08-21

    Reactive nanospray desorption electrospray ionization (nano-DESI) combined with high-resolution mass spectrometry was utilized for the analysis of secondary organic aerosol produced through ozonolysis of limonene (LSOA). Previous studies have shown that LSOA constituents are multifunctional compounds containing at least one aldehyde or ketone groups. In this study, we used the selectivity of the Girard's reagent T (GT) toward carbonyl compounds to examine the utility of reactive nano-DESI for the analysis of complex organic mixtures. In these experiments, 1-100 μM GT solutions were used as the working solvents for reactive nano-DESI analysis. Abundant products from the single addition of GT to LSOA constituents were observed at GT concentrations in excess of 10 μM. We found that LSOA dimeric and trimeric compounds react with GT through a simple addition reaction resulting in formation of the carbinolamine derivative. In contrast, reactions of GT with monomeric species result in the formation of both the carbinolamine and the hydrazone derivatives. In addition, several monomers did not react with GT on the time scale of our experiment. These molecules were characterized by relatively high values of the double bond equivalent and low oxygen content. Furthermore, because addition of a charged GT tag to a neutral molecule eliminates the discrimination against the low proton affinity compounds in the ionization process, reactive nano-DESI analysis enables quantification of individual compounds in the complex mixture. For example, we were able to estimate for the first time the amounts of dimers and trimers in the LSOA mixture. Specifically, we found that the most abundant LSOA dimer was detected at the ~0.5 pg level and the total amount of dimers and trimers in the analyzed sample was ~11 pg. Our results indicate that reactive nano-DESI is a valuable approach for examining the presence of specific functional groups and for the quantification of compounds possessing

  10. Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants

    SciTech Connect

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

    1994-05-01

    A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4{degree}C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range.

  11. Chemical analysis of diesel engine nanoparticles using a nano-DMA/thermal desorption particle beam mass spectrometer.

    PubMed

    Tobias, H J; Beving, D E; Ziemann, P J; Sakurai, H; Zuk, M; McMurry, P H; Zarling, D; Waytulonis, R; Kittelson, D B

    2001-06-01

    Diesel engines are known to emit high number concentrations of nanoparticles (diameter < 50 nm), but the physical and chemical mechanisms by which they form are not understood. Information on chemical composition is lacking because the small size, low mass concentration, and potential for contamination of samples obtained by standard techniques make nanoparticles difficult to analyze. A nano-differential mobility analyzer was used to size-select nanoparticles (mass median diameter approximately 25-60 nm) from diesel engine exhaust for subsequent chemical analysis by thermal desorption particle beam mass spectrometry. Mass spectra were used to identify and quantify nanoparticle components, and compound molecular weights and vapor pressures were estimated from calibrated desorption temperatures. Branched alkanes and alkyl-substituted cycloalkanes from unburned fuel and/or lubricating oil appear to contribute most of the diesel nanoparticle mass. The volatility of the organic fraction of the aerosol increases as the engine load decreases and as particle size increases. Sulfuric acid was also detected at estimated concentrations of a few percent of the total nanoparticle mass. The results are consistent with a mechanism of nanoparticle formation involving nucleation of sulfuric acid and water, followed by particle growth by condensation of organic species. PMID:11414024

  12. Few layer graphene matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Cho, Donghyun; Hong, Sangsu; Shim, Sangdeok

    2013-08-01

    We present the employment of few layer graphene (FLG) as a matrix for the analysis of low molecular weight polymeric compounds using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The practicality of FLG as a matrix for MALDI experiments is demonstrated by analyzing low molecular weight polymers, polar polyethylene glycol (PEG) of 1000 Da and nonpolar polymethylmethacrylate (PMMA) of 650 Da. The high quality MS spectra without low-mass interference signals without any further sampling procedure were acquired. PMID:23882840

  13. Rapid characterization of polyalcohols by silylation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Adeuya, Anthony; Price, Neil

    2007-01-01

    A matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry method for rapidly enumerating hydroxyl groups in analytes is described, and applied to some common polyalcohols (erythritol, mannitol and xylitol). Polyalcohols were derivatized with trimethylsilylimidazole (TMSI) either separately or as mixtures, and were analyzed, without chromatographic separation or purification. The mass spectra revealed consecutive peaks that are separated by 72 m/z units as a consequence of displacement of one hydroxyl hydrogen atom by one TMS group. The number of observed peaks was used to confirm the number of hydroxyl groups in each analyte. PMID:17994528

  14. Analysis of fatty acids by graphite plate laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Park, K H; Kim, H J

    2001-01-01

    Fatty acids obtained from triglycerides (trioelin, tripalmitin), foods (milk, corn oil), and phospholipids (phosphotidylcholine, phosphotidylserine, phosphatidic acid) upon alkaline hydrolysis were observed directly without derivatization by graphite plate laser desorption/ionization time-of-flight mass spectrometry (GPLDI-TOFMS). Mass-to-charge ratios predicted for sodium adducts of expected fatty acids (e.g. palmitic, oleic, linoleic and arachidonic acids) were observed without interference. Although at present no quantitation is possible, the graphite plate method enables a simple and rapid qualitative analysis of fatty acids. PMID:11507764

  15. Thermal desorption-gas chromatography-mass spectrometry method to determine phthalate and organophosphate esters from air samples.

    PubMed

    Aragón, M; Borrull, F; Marcé, R M

    2013-08-16

    A method based on thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed to determine four organophosphate esters, seven phthalate esters, and bis(2-ethylhexyl) adipate in the gas phase from harbour and urban air samples. The method involves the sampling of 1.5L of air in a Tenax TA sorbent tube followed by thermal desorption (using a Tenax TA cryogenic trap) coupled to gas chromatography-mass spectrometry. The repeatability of the method expressed as %RSD (n=3) is less than 15% and the MQLs are between 0.007μgm(-3) (DMP, TBP, BBP, TPP and DnOP) and 6.7μgm(-3) (DEHP). The method was successfully applied in two areas (urban and harbour) testing two and three points in each one, respectively. Some of these compounds were found in both urban and harbour samples. Di-(2-ethylhexyl)phthalate was the most abundant compound found in both areas at concentration levels between 6.7μgm(-3) and 136.4μgm(-3). This study demonstrates that thermal desorption is an efficient method for the determination of these semi-volatile compounds in the gas phase fraction of air samples. PMID:23859797

  16. Surface-assisted laser desorption-ionization mass spectrometry on titanium dioxide (TiO2) nanotube layers.

    PubMed

    Piret, Gaëlle; Kim, Doohun; Drobecq, Hervé; Coffinier, Yannick; Melnyk, Oleg; Schmuki, Patrik; Boukherroub, Rabah

    2012-07-01

    The paper reports on the use of a titanium oxide (TiO(2)) nanotube layer as a sensitive substrate for surface-assisted laser desorption-ionization mass spectrometry (SALDI-MS) of peptides and small molecules. The nanotube layers were prepared by electrochemical anodization of titanium foil. The optimized TiO(2) nanotubes morphology coupled to a controlled surface chemistry allowed desorption-ionization (D/I) of a peptide mixture (Mix1) with a detection limit of 10 femtomoles for the neurotensin peptide. The performance of the TiO(2) nanotubes for the D/I of small molecules was also tested for the detection of sutent, a small tyrosine kinase inhibitor, and verapamil. A detection limit of 50 fmol was obtained for these molecules, as compared to 500 fmol using classical matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). Both amorphous and anatase TiO(2) layers displayed a comparable performance for D/I of analyte molecules. In a control experiment, we have performed D/I of analyte molecules on a flat TiO(2) layer. The absence of signal emphasizes the role of the nanostructured substrate in the D/I process. PMID:22624145

  17. Jarosite as a Storage Mineral for Small Organic Molecules: Investigations of Natural Samples Using an 'In Situ' Laser Desorption Fourier Transform Mass Spectrometry Technique

    NASA Astrophysics Data System (ADS)

    Kotler, J. M.; Hinman, N. W.; Yan, B.; Stoner, D. L.; Scott, J. R.

    2007-03-01

    The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide including jarosite precipitated in the lab by acidothiobacillus ferroxidans.

  18. Nanoscale silicon surface-assisted laser desorption/ionization mass spectrometry: environment stability and activation by simple vacuum oven desiccation.

    PubMed

    Tsao, Chia-Wen; Lin, Yuan-Jing; Chen, Pi-Yu; Yang, Yu-Liang; Tan, Say Hwa

    2016-08-01

    Nanoscale silicon surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is an emerging matrix-free, highly sensitive MS analysis method. An important challenge in using nanoscale silicon SALDI-MS analysis is the aging and stability of silicon after storage in various environments. No proper nanoscale silicon SALDI-MS activation procedure has been reported to solve this issue. This study investigated the sensitivity, wettability, and surface oxidation behavior of nanoscale silicon surface SALDI-MS in a room, an inert gas atmosphere, and a vacuum environment. A simple vacuum oven desiccation was proposed to activate the SALDI-MS surface, and the limit of detection was further enhanced 1000 times to a 500 attomole level using this approach. The long-term stability and desorption/ionization mechanism were also investigated. PMID:27315049

  19. Automated ambient desorption-ionization platform for surface imaging integrated with a commercial Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Pól, Jaroslav; Vidová, Veronika; Kruppa, Gary; Kobliha, Václav; Novák, Petr; Lemr, Karel; Kotiaho, Tapio; Kostiainen, Risto; Havlícek, Vladimír; Volný, Michael

    2009-10-15

    A fully automated atmospheric pressure ionization platform has been built and coupled with a commercial high-resolution Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) instrument. The outstanding performance of this instrument allowed screening on the basis of exact masses in imaging mode. The main novel aspect was in the integration of the atmospheric pressure ionization imaging into the current software for matrix-assisted laser desorption ionization (MALDI) imaging, which allows the user of this commercial dual-source mass spectrometer to perform MALDI-MS and different ambient MS imaging from the same user interface and to utilize the same software tools. Desorption electrospray ionization (DESI) and desorption atmospheric pressure photoionization (DAPPI) were chosen to test the ambient surface imaging capabilities of this new ionization platform. Results of DESI imaging experiments performed on brain tissue sections are in agreement with previous MS imaging reports obtained by DESI imaging, but due to the high resolution and mass accuracy of the FTICR instrument it was possible to resolve several ions at the same nominal mass in the DESI-MS spectra of brain tissue. These isobaric interferences at low resolution are due to the overlap of ions from different lipid classes with different biological relevance. It was demonstrated that with the use of high-resolution MS fast imaging screening of lipids can be achieved without any preseparation steps. DAPPI, which is a relatively new and less developed ambient ionization technique compared to DESI, was used in imaging mode for the first time ever. It showed promise in imaging of phytocompounds from plant leaves, and selective ionization of a sterol lipid was achieved by DAPPI from a brain tissue sample. PMID:19761221

  20. Black phosphorus-assisted laser desorption ionization mass spectrometry for the determination of low-molecular-weight compounds in biofluids.

    PubMed

    He, Xiao-Mei; Ding, Jun; Yu, Lei; Hussain, Dilshad; Feng, Yu-Qi

    2016-09-01

    Quantitative analysis of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been a challenging task due to matrix-derived interferences in low m/z region and poor reproducibility of MS signal response. In this study, we developed an approach by applying black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix for the quantitative analysis of small molecules for the first time. Black phosphorus-assisted laser desorption/ionization mass spectrometry (BP/ALDI-MS) showed clear background and exhibited superior detection sensitivity toward quaternary ammonium compounds compared to carbon-based materials. By combining stable isotope labeling (SIL) strategy with BP/ALDI-MS (SIL-BP/ALDI-MS), a variety of analytes labeled with quaternary ammonium group were sensitively detected. Moreover, the isotope-labeled forms of analytes also served as internal standards, which broadened the analyte coverage of BP/ALDI-MS and improved the reproducibility of MS signals. Based on these advantages, a reliable method for quantitative analysis of aldehydes from complex biological samples (saliva, urine, and serum) was successfully established. Good linearities were obtained for five aldehydes in the range of 0.1-20.0 μM with correlation coefficients (R (2)) larger than 0.9928. The LODs were found to be 20 to 100 nM. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 10.4 %, and the recoveries in saliva samples ranged from 91.4 to 117.1 %. Taken together, the proposed SIL-BP/ALDI-MS strategy has proved to be a reliable tool for quantitative analysis of aldehydes from complex samples. Graphical Abstract An approach for the determination of small molecules was developed by using black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix. PMID:27382971

  1. Whole-body Mass Spectrometry Imaging by Infrared Matrix-assisted Laser Desorption Electrospray Ionization (IR-MALDESI).

    PubMed

    Nazari, Milad; Bokhart, Mark T; Muddiman, David C

    2016-01-01

    Ambient ionization sources for mass spectrometry (MS) have been the subject of much interest in the past decade. Matrix-assisted laser desorption electrospray ionization (MALDESI) is an example of such methods, where features of matrix-assisted laser desorption/ionization (MALDI) (e.g., pulsed nature of desorption) and electrospray ionization (ESI) (e.g., soft-ionization) are combined. One of the major advantages of MALDESI is its inherent versatility. In MALDESI experiments, an ultraviolet (UV) or infrared (IR) laser can be used to resonantly excite an endogenous or exogenous matrix. The choice of matrix is not analyte dependent, and depends solely on the laser wavelength used for excitation. In IR-MALDESI experiments, a thin layer of ice is deposited on the sample surface as an energy-absorbing matrix. The IR-MALDESI source geometry has been optimized using statistical design of experiments (DOE) for analysis of liquid samples as well as biological tissue specimens. Furthermore, a robust IR-MALDESI imaging source has been developed, where a tunable mid-IR laser is synchronized with a computer controlled XY translational stage and a high resolving power mass spectrometer. A custom graphical user interface (GUI) allows user selection of the repetition rate of the laser, number of shots per voxel, step-size of the sample stage, and the delay between the desorption and scan events for the source. IR-MALDESI has been used in variety of applications such as forensic analysis of fibers and dyes and MSI of biological tissue sections. Distribution of different analytes ranging from endogenous metabolites to exogenous xenobiotics within tissue sections can be measured and quantified using this technique. The protocol presented in this manuscript describes major steps necessary for IR-MALDESI MSI of whole-body tissue sections. PMID:27077488

  2. Characterization of carbon surface chemistry by combined temperature programmed desorption with in situ X-ray photoelectron spectrometry and temperature programmed desorption with mass spectrometry analysis.

    PubMed

    Brender, Patrice; Gadiou, Roger; Rietsch, Jean-Christophe; Fioux, Philippe; Dentzer, Joseph; Ponche, Arnaud; Vix-Guterl, Cathie

    2012-03-01

    The analysis of the surface chemistry of carbon materials is of prime importance in numerous applications, but it is still a challenge to identify and quantify the surface functional groups which are present on a given carbon. Temperature programmed desorption with mass spectrometry analysis (TPD-MS) and X-ray photoelectron spectroscopy with an in situ heating device (TPD-XPS) were combined in order to improve the characterization of carbon surface chemistry. TPD-MS analysis allowed the quantitative analysis of the released gases as a function of temperature, while the use of a TPD device inside the XPS setup enabled the determination of the functional groups that remain on the surface at the same temperatures. TPD-MS results were then used to add constraints on the deconvolution of the O1s envelope of the XPS spectra. Furthermore, a better knowledge of the evolution of oxygen functional groups with temperature during a thermal treatment could be obtained. Hence, we show here that the combination of these two methods allows to increase the reliability of the analysis of the surface chemistry of carbon materials. PMID:22242697

  3. Mass spectrometric imaging and laser desorption ionization (LDI) with ice as a matrix using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Berry, Jamal Ihsan

    The desorption of biomolecules from frozen aqueous solutions on metal substrates with femtosecond laser pulses is presented for the first time. Unlike previous studies using nanosecond pulses, this approach produces high quality mass spectra of biomolecules repeatedly and reproducibly. This novel technique allows analysis of biomolecules directly from their native frozen environments. The motivation for this technique stems from molecular dynamics computer simulations comparing nanosecond and picosecond heating of water overlayers frozen on Au substrates which demonstrate large water cluster formation and ejection upon substrate heating within ultrashort timescales. As the frozen aqueous matrix and analyte molecules are transparent at the wavelengths used, the laser energy is primarily absorbed by the substrate, causing rapid heating and explosive boiling of the ice overlayer, followed by the ejection of ice clusters and the entrained analyte molecule. Spectral characteristics at a relatively high fluence of 10 J/cm 2 reveal the presence of large molecular weight metal clusters when a gold substrate is employed, with smaller cluster species observed from frozen aqueous solutions on Ag, Cu, and Pb substrates. The presence of the metal clusters is indicative of an evaporative cooling mechanism which stabiles cluster ion formation and the ejection of biomolecules from frozen aqueous solutions. Solvation is necessary as the presence of metal clusters and biomolecular ion signals are not observed from bare metal substrates in absence of the frozen overlayer. The potential for mass spectrometric imaging with femtosecond LDI of frozen samples is also presented. The initial results for the characterization of peptides and peptoids linked to combinatorial beads frozen in ice and the assay of frozen brain tissue from the serotonin transporter gene knockout mouse via LDI imaging are discussed. Images of very good quality and resolution are obtained with 400 nm, 200 fs pulses

  4. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for the Discrimination of Food-Borne Microorganisms

    PubMed Central

    Mazzeo, Maria Fiorella; Sorrentino, Alida; Gaita, Marcello; Cacace, Giuseppina; Di Stasio, Michele; Facchiano, Angelo; Comi, Giuseppe; Malorni, Antonio; Siciliano, Rosa Anna

    2006-01-01

    A methodology based on matrix-assisted laser desorption ionization-time of flight mass spectrometry of intact bacterial cells was used for rapid discrimination of 24 bacterial species, and detailed analyses to identify Escherichia coli O157:H7 were carried out. Highly specific mass spectrometric profiles of pathogenic and nonpathogenic bacteria that are well-known major food contaminants were obtained, uploaded in a specific database, and made available on the Web. In order to standardize the analytical protocol, several experimental, sample preparation, and mass spectrometry parameters that can affect the reproducibility and accuracy of data were evaluated. Our results confirm the conclusion that this strategy is a powerful tool for rapid and accurate identification of bacterial species and that mass spectrometric methodologies could play an essential role in polyphasic approaches to the identification of pathogenic bacteria. PMID:16461665

  5. Desorption Electrospray Ionization (DESI) Mass Spectrometric Imaging of the Distribution of Rohitukine in the Seedling of Dysoxylum binectariferum Hook. F

    PubMed Central

    Mohana Kumara, Patel; Srimany, Amitava; Arunan, Suganya; Ravikanth, Gudasalamani; Uma Shaanker, Ramanan; Pradeep, Thalappil

    2016-01-01

    Ambient ionization mass spectrometric imaging of all parts of the seedling of Dysoxylum binectariferum Hook. f (Meliaceae) was performed to reconstruct the molecular distribution of rohitukine (Rh) and related compounds. The species accumulates Rh, a prominent chromone alkaloid, in its seeds, fruits, and stem bark. Rh possesses anti-inflammatory, anti-cancer, and immuno-modulatory properties. Desorption electrospray ionization mass spectrometry imaging (DESI MSI) and electrospray ionization (ESI) tandem mass spectrometry (MS/MS) analysis detected Rh as well as its glycosylated, acetylated, oxidized, and methoxylated analogues. Rh was predominantly distributed in the main roots, collar region of the stem, and young leaves. In the stem and roots, Rh was primarily restricted to the cortex region. The identities of the metabolites were assigned based on both the fragmentation patterns and exact mass analyses. We discuss these results, with specific reference to the possible pathways of Rh biosynthesis and translocation during seedling development in D. binectariferum. PMID:27362422

  6. Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

    SciTech Connect

    Cha, Sangwon

    2008-01-01

    Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS protocols with various alternative assisting materials were developed and applied to many biological systems of interest. Colloidal graphite was used as a matrix for IMS of small molecules for the first time and methodologies for analyses of small metabolites in rat brain tissues, fruits, and plant tissues were developed. With rat brain tissues, the signal enhancement for cerebroside species by colloidal graphite was observed and images of cerebrosides were successfully generated by IMS. In addition, separation of isobaric lipid ions was performed by imaging tandem MS. Directly from Arabidopsis flowers, flavonoids were successfully profiled and heterogeneous distribution of flavonoids in petals was observed for the first time by graphite-assisted LDI(GALDI) IMS.

  7. Cellular-level mass spectrometry imaging using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) by oversampling.

    PubMed

    Nazari, Milad; Muddiman, David C

    2015-03-01

    Mass spectrometry imaging (MSI) allows for the direct and simultaneous analysis of the spatial distribution of molecular species from sample surfaces such as tissue sections. One of the goals of MSI is monitoring the distribution of compounds at the cellular resolution in order to gain insights about the biology that occurs at this spatial level. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) imaging of cervical tissue sections was performed using a spot-to-spot distance of 10 μm by utilizing the method of oversampling, where the target plate is moved by a distance that is less than the desorption radius of the laser. In addition to high spatial resolution, high mass accuracy (±1 ppm) and high mass resolving power (140,000 at m/z = 200) were achieved by coupling the IR-MALDESI imaging source to a hybrid quadrupole Orbitrap mass spectrometer. Ion maps of cholesterol in tissues were generated from voxels containing <1 cell, on average. Additionally, the challenges of imaging at the cellular level in terms of loss of sensitivity and longer analysis time are discussed. PMID:25486925

  8. Cellular Level Mass Spectrometry Imaging using Infrared Matrix Assisted Laser Desorption Electrospray Ionization (IR-MALDESI) by Oversampling

    PubMed Central

    Nazari, Milad; Muddiman, David C.

    2014-01-01

    Mass spectrometry imaging (MSI) allows for the direct and simultaneous analysis of the spatial distribution of molecular species from sample surfaces such as tissue sections. One of the goals of MSI is monitoring the distribution of compounds at the cellular resolution in order to gain insights about the biology that occurs at this spatial level. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) imaging of cervical tissue sections was performed using a spot-to-spot distance of 10 μm by utilizing the method of oversampling; where the target plate is moved by a distance that is less than the desorption radius of the laser. In addition to high spatial resolution, high mass accuracy (± 1 ppm) and high mass resolving power (140,000 at m/z=200) was achieved by coupling the IR-MALDESI imaging source to a hybrid quadrupole Orbitrap mass spectrometer. Ion maps of cholesterol in tissues were generated from voxels containing <1 cell, on average. Additionally, the challenges of imaging at the cellular level in terms of loss of sensitivity and longer analysis time are discussed. PMID:25486925

  9. Evaluation of combined matrix-assisted laser desorption/ionization time-of-flight and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry experiments for peptide mass fingerprinting analysis.

    PubMed

    da Silva, David; Wasselin, Thierry; Carré, Vincent; Chaimbault, Patrick; Bezdetnaya, Lina; Maunit, Benoît; Muller, Jean-François

    2011-07-15

    Peptide Mass Fingerprinting (PMF) is still of significant interest in proteomics because it allows a large number of complex samples to be rapidly screened and characterized. The main part of post-translational modifications is generally preserved. In some specific cases, PMF suffers from ambiguous or unsuccessful identification. In order to improve its reliability, a combined approach using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) was evaluated. The study was carried out on bovine serum albumin (BSA) digest. The influence of several important parameters (the matrix, the sample preparation method, the amount of the analyte) on the MOWSE score and the protein sequence coverage were evaluated to allow the identification of specific effects. A careful investigation of the sequence coverage obtained by each kind of experiment ensured the detection of specific peptides for each experimental condition. Results highlighted that DHB-FTICRMS and DHB- or CHCA-TOFMS are the most suited combinations of experimental conditions to achieve PMF analysis. The association (convolution) of the data obtained by each of these techniques ensured a significant increase in the MOWSE score and the protein sequence coverage. PMID:21638364

  10. Filtration efficiency validation of glass wool during thermal desorption-gas chromatography-mass spectrometer analysis of fine atmospheric particles.

    PubMed

    Hao, Liang; Wu, Dapeng; Ding, Kun; Meng, Hu; Yan, Xiaohui; Guan, Yafeng

    2015-02-01

    Thermal desorption-gas chromatography-mass spectrometer (TD-GC-MS) technique has been widely used for analysis of semi-violate organic compounds on atmospheric aerosol. To prevent GC column from being damaged by fine solid particles during thermal desorption process, glass wool as filter mat is indispensible. However, the filtration efficiency has never been validated. In this paper, the most penetrating particle size and the minimum packing thickness of glass wool were calculated based on classical filtration theory. According to the calculation results, packing parameters of glass wool were optimized experimentally using silica particles. It is demonstrated that glass wool with a packing thickness of 30 mm, solidity of 0.039 can effectively block these fine solid particles from penetrating at normal thermal desorption conditions (T=300°C, u=0.4-4 cm/s). Finally, the filtration efficiency of glass wool was further confirmed with real PM2.5 samples. Under the validated filtration condition, TD-GC-MS was applied for the analysis of non-polar organic compounds on real PM2.5 samples, and very good results were obtained. PMID:25578046

  11. Detection of native protein ions in aqueous solution under ambient conditions by electrospray laser desorption/ionization mass spectrometry.

    PubMed

    Shiea, Jentaie; Yuan, Cheng-Hui; Huang, Min-Zong; Cheng, Sy-Chyi; Ma, Ya-Lin; Tseng, Wei-Lung; Chang, Hui-Chiu; Hung, Wen-Chun

    2008-07-01

    Liquid electrospray laser desorption/ionization (ELDI) mass spectrometry allows desorption and ionization of proteins directly from aqueous solutions and biological fluids under ambient conditions. Native protein ions such as those of myoglobin, cytochrome c, and hemoglobin were obtained. A droplet (ca. 5 microL) containing the protein molecules and micrometer-sized particles (e.g., carbon graphite powder) is irradiated with a pulsed UV laser. The laser energy adsorbed by the inert particles is transferred to the surrounding solvent and protein molecules, leading to their desorption; the desorbed gaseous molecules are then postionized within an electrospray (ESI) plume to generate the ESI-like protein ions. With the use of this technique, we detected only the protonated protein ions in various biological fluids (including human tears, cow milk, serum, and bacterial extracts) without interference from their corresponding sodiated or potassiated adduct ions. In addition, we rapidly quantified the levels of glycosylated hemoglobin present in drops of whole blood obtained from diabetic patients without the need of sample pretreatment. PMID:18510347

  12. High-Resolution Live-Cell Imaging and Analysis by Laser Desorption/Ionization Droplet Delivery Mass Spectrometry.

    PubMed

    Lee, Jae Kyoo; Jansson, Erik T; Nam, Hong Gil; Zare, Richard N

    2016-05-17

    We have developed a new ambient-ionization mass spectrometric technique named laser desorption/ionization droplet delivery mass spectrometry (LDIDD-MS). LDIDD-MS permits high-resolution, high-sensitivity imaging of tissue samples as well as measurements of both single-cell apoptosis and live-cell exocytosis. A pulsed (15 Hz) UV laser beam (266 nm) is focused on a surface covered with target analytes to trigger their desorption and ionization. A spray of liquid droplets is simultaneously directed onto the laser-focused surface region to capture the ionized analytes and deliver them to a mass spectrometer. The approach of rapid and effective capturing of molecules after laser desorption/ionization allows the limit of detection for the amino acid lysine to be as low as 2 amol under ambient ionization conditions. Two-dimensional maps of the desorbed/ionized species are recorded by moving the sample on an XY translational stage. The spatial resolution for imaging with LDIDD-MS was determined to be 2.4 μm for an ink-printed pattern and 3 μm for mouse brain tissue. We applied LDIDD-MS to single-cell analysis of apoptotic HEK cells. Differences were observed in the profiles of fatty acids and lipids between healthy HEK cells and those undergoing apoptosis. We observed upregulation of phosphatidylcholine (PC) with a relatively shorter carbon chain length and downregulation of PC with a relatively longer carbon chain length. We also applied LDIDD-MS for a real-time direct measurements of live-cell exocytosis. The catecholamine dopamine and trace amines (phenethylamine and tyramine) were detected from live PC12 cells without damaging them. PMID:27110027

  13. Californium-252 plasma desorption with Fourier-transform mass spectrometry. Report for 1 January 1930-June 1987

    SciTech Connect

    Loo, J.A.; Williams, E.R.; Amster, I.J.; Furlong, J.J.; Wang, B.H.

    1987-07-15

    Plasma desorption (PD) using /sup 252/CF produces analytically useful Fourier-transform (FT) mass spectra from compounds of molecular weights to 2000. In direct comparison to PD spectra measured conventionally on time-of-flight instruments, PD-FT spectra have much higher resolution and useful fragment-ion information, but have higher backgrounds and orders-of-magnitude lower ion-collection efficiencies. Signal levels have been improved substantially by depositing the sample with glutathione or on nitrocellulose, by repeated (1-2 minutes) spectral measurements during ion production without ion quenching, and by separate optimization of the potential on the sample holder and trapping plates.

  14. Organic chemical analysis on a microscopic scale using two-step laser desorption/laser ionization mass spectrometry

    NASA Technical Reports Server (NTRS)

    Kovalenko, L. J.; Philippoz, J.-M.; Bucenell, J. R.; Zenobi, R.; Zare, R. N.

    1991-01-01

    The distribution of PAHs in the Allende meteorite has been measured using two-step laser desorption and laser multiphoton-ionization mass spectrometry. This method enables in situ analysis (with a spatial resolution of 1 mm or better) of selected organic molecules. Results show that PAH concentrations are locally high compared to the average concentration found by analysis of pulverized samples, and are found primarily in the fine-grained matrix; no PAHs were detected in the interiors of individual chondrules at the detection limit (about 0.05 ppm).

  15. Collection method for chemical particulates on surfaces with detection using thermal desorption-ion trap mass spectrometry.

    PubMed

    Ewing, K J; Gibson, D; Sanghera, J; Miklos, F

    2013-05-01

    Successful analysis of particulate/low vapor pressure analytes such as explosives and toxic chemicals, and commercial pesticides require new sampling tools that enable detection of these analytes using current vapor phase detection instruments. We describe a sampling approach that uses stainless steel screens coated with a sticky polydimethyl siloxane (PDMS) coating to capture particulates from surfaces. Preliminary results for the collection of dimethyl methylphosphonate (DMMP) sorbed onto silica gel (SG) particulates (DMMP/SG) from a surface with subsequent analysis by thermal desorption-cylindrical ion trap mass spectrometry (TD-CITMS) are reported. PMID:23601282

  16. Detection of trace organics in Mars analog samples containing perchlorate by laser desorption/ionization mass spectrometry.

    PubMed

    Li, Xiang; Danell, Ryan M; Brinckerhoff, William B; Pinnick, Veronica T; van Amerom, Friso; Arevalo, Ricardo D; Getty, Stephanie A; Mahaffy, Paul R; Steininger, Harald; Goesmann, Fred

    2015-02-01

    Evidence from recent Mars missions indicates the presence of perchlorate salts up to 1 wt % level in the near-surface materials. Mixed perchlorates and other oxychlorine species may complicate the detection of organic molecules in bulk martian samples when using pyrolysis techniques. To address this analytical challenge, we report here results of laboratory measurements with laser desorption mass spectrometry, including analyses performed on both commercial and Mars Organic Molecule Analyzer (MOMA) breadboard instruments. We demonstrate that the detection of nonvolatile organics in selected spiked mineral-matrix materials by laser desorption/ionization (LDI) mass spectrometry is not inhibited by the presence of up to 1 wt % perchlorate salt. The organics in the sample are not significantly degraded or combusted in the LDI process, and the parent molecular ion is retained in the mass spectrum. The LDI technique provides distinct potential benefits for the detection of organics in situ on the martian surface and has the potential to aid in the search for signs of life on Mars. PMID:25622133

  17. Structural characterization of phospholipids by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Marto, J A; White, F M; Seldomridge, S; Marshall, A G

    1995-11-01

    Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode. PMID:8633761

  18. Direct detection of pharmaceuticals and personal care products from aqueous samples with thermally-assisted desorption electrospray ionization mass spectrometry.

    PubMed

    Campbell, Ian S; Ton, Alain T; Mulligan, Christopher C

    2011-07-01

    An ambient mass spectrometric method based on desorption electrospray ionization (DESI) has been developed to allow rapid, direct analysis of contaminated water samples, and the technique was evaluated through analysis of a wide array of pharmaceutical and personal care product (PPCP) contaminants. Incorporating direct infusion of aqueous sample and thermal assistance into the source design has allowed low ppt detection limits for the target analytes in drinking water matrices. With this methodology, mass spectral information can be collected in less than 1 min, consuming ~100 μL of total sample. Quantitative ability was also demonstrated without the use of an internal standard, yielding decent linearity and reproducibility. Initial results suggest that this source configuration is resistant to carryover effects and robust towards multi-component samples. The rapid, continuous analysis afforded by this method offers advantages in terms of sample analysis time and throughput over traditional hyphenated mass spectrometric techniques. PMID:21953111

  19. Matrix-assisted laser desorption/ionisation mass spectrometry imaging and its development for plant protein imaging

    PubMed Central

    2011-01-01

    Matrix-Assisted Laser Desorption/Ionisation (MALDI) mass spectrometry imaging (MSI) uses the power of high mass resolution time of flight (ToF) mass spectrometry coupled to the raster of lasers shots across the cut surface of tissues to provide new insights into the spatial distribution of biomolecules within biological tissues. The history of this technique in animals and plants is considered and the potential for analysis of proteins by this technique in plants is discussed. Protein biomarker identification from MALDI-MSI is a challenge and a number of different approaches to address this bottleneck are discussed. The technical considerations needed for MALDI-MSI are reviewed and these are presented alongside examples from our own work and a protocol for MALDI-MSI of proteins in plant samples. PMID:21726462

  20. Rapid identification of haloarchaea and methanoarchaea using the matrix assisted laser desorption/ionization time-of-flight mass spectrometry

    PubMed Central

    Shih, Chao-Jen; Chen, Sheng-Chung; Weng, Chieh-Yin; Lai, Mei-Chin; Yang, Yu-Liang

    2015-01-01

    The aim of this study was to classify certain environmental haloarchaea and methanoarchaea using matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and to expand the archaeal mass spectral database. A total of 69 archaea were collected including type strains and samples isolated locally from different environments. For extraction of the haloarchaeal total cell peptides/proteins, a simple method of acetonitrile extraction was developed. Cluster analysis conducted with the MALDI-TOF MS data overcame the high divergence in intragenomic 16S rRNA sequences in haloarchaea and clearly distinguished Methanohalophilus mahii from M. portucalensis. Putative biomarkers that can distinguish several particular archaeal genera were also assigned. In conclusion, this study expands the mass spectral database of peptide/protein fingerprints from bacteria and fungi to the archaea domain and provides a rapid identification platform for environmental archaeal samples. PMID:26541644

  1. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  2. Direct Detection of Pharmaceuticals and Personal Care Products from Aqueous Samples with Thermally-Assisted Desorption Electrospray Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Campbell, Ian S.; Ton, Alain T.; Mulligan, Christopher C.

    2011-07-01

    An ambient mass spectrometric method based on desorption electrospray ionization (DESI) has been developed to allow rapid, direct analysis of contaminated water samples, and the technique was evaluated through analysis of a wide array of pharmaceutical and personal care product (PPCP) contaminants. Incorporating direct infusion of aqueous sample and thermal assistance into the source design has allowed low ppt detection limits for the target analytes in drinking water matrices. With this methodology, mass spectral information can be collected in less than 1 min, consuming ~100 μL of total sample. Quantitative ability was also demonstrated without the use of an internal standard, yielding decent linearity and reproducibility. Initial results suggest that this source configuration is resistant to carryover effects and robust towards multi-component samples. The rapid, continuous analysis afforded by this method offers advantages in terms of sample analysis time and throughput over traditional hyphenated mass spectrometric techniques.

  3. Thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry using particle suspension matrices.

    PubMed

    Crecelius, Anna; Clench, Malcolm R; Richards, Don S; Parr, Vic

    2002-06-01

    Particle suspension matrices have been successfully utilized for the analysis of tetracycline antibiotics by thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (TLC-MALDI-TOF-MS). Particles of different materials and sizes have been investigated (Co-UFP, TiN, TiO2, Graphite and Silicon) by applying particle suspensions to eluted TLC plates. Mass spectra and mass chromatograms have been recorded directly from the TLC plates. Strong cationization by sodium and potassium was obtained in the positive ion mode, with [M+Na-NH3]+ ions being the predominant signals. The TLC-MALDI mass spectra recorded from graphite suspensions showed the lowest background noise and the highest peak intensities from the range of suspension matrices studied. The mass accuracy from graphite films was improved by adding the peptide Phe-Phe to the graphite suspensions. This allowed internal recalibration of the TLC-MALDI mass spectra acquired during a run. One major potential advantage of TLC-MALDI-TOF-MS has been demonstrated in the analysis of chlortetracycline and tetracycline in a mixture of oxytetracycline, chlortetracycline, tetracycline and minocycline. Examination of the TLC plate prior to MALDI analysis showed only an unresolved spot for chlortetracycline and tetracycline. However by investigation of the MALDI mass spectra and plotting of single ion chromatograms separate peaks for chlortetracycline and tetracycline could be obtained. PMID:12134822

  4. Highly Reproducible Laser Beam Scanning Device for an Internal Source Laser Desorption Microprobe Fourier Transform Mass Spectrometer

    SciTech Connect

    Scott, Jill Rennee; Tremblay, Paul Leland

    2002-03-01

    Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (~5 µm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ~9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz's law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies.

  5. Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

    PubMed Central

    Rudd, David; Benkendorff, Kirsten; Voelcker, Nicolas H.

    2015-01-01

    Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. PMID:25786067

  6. An improvement of matrix-assisted laser desorption/ionization mass spectrometry using an infrared tunable free electron laser

    NASA Astrophysics Data System (ADS)

    Naito, Yasuhide; Yoshihashi-Suzuki, Sachiko; Ishii, Katsunori; Awazu, Kunio

    2004-08-01

    Matrix-assisted laser desorption/ionization (MALDI) combined with time-of-flight mass spectrometry (TOFMS) is a powerful yet robust tool for protein identification, due to its high sensitivity and theoretically unlimited detectable mass range. A large part of functional proteins, such as membrane proteins, are insoluble as native forms in a matrix solution without a strong denaturing condition, hence are not amenable to the conventional MALDI-TOFMS analysis. Aiming at overcoming this difficulty, we have developed a novel MALDI technique (UV/FEL-MALDI). An infrared free electron laser (IR-FEL) has a wide tunability in a mid-IR range and is quite attractive as a source of selective vibrational excitation. The FEL wavelength can be tuned to activate a denaturant, which impedes the conventional MALDI process, without an excess heating of analyte molecules. This scheme lets a dense denaturant to be used for the MALDI sample preparation of insoluble proteins. A simultaneous use of the FEL with a nitrogen pulse laser for MALDI achieves spatially and temporally defined desorption, which is essential to TOFMS detection, while specificity and selectivity owing to an FEL wavelength can be conserved. Some attractive features of the protein clustering have been found in the application of UV/FEL-MALDI to hair keratins, which was chosen as a model of insoluble proteins.

  7. Electrospun Nanofiber Mats as "Smart Surfaces" for Desorption Electrospray Ionization Mass Spectrometry (DESI MS)-Based Analysis and Imprint Imaging.

    PubMed

    Hemalatha, R G; Ganayee, Mohd Azhardin; Pradeep, T

    2016-06-01

    In this paper, desorption electrospray ionization mass spectrometry (DESI MS)-based molecular analysis and imprint imaging using electrospun nylon-6 nanofiber mats are demonstrated for various analytical contexts. Uniform mats of varying thicknesses composed of ∼200 nm diameter fibers were prepared using needleless electrospinning. Analytical applications requiring rapid understanding of the analytes in single drops, dyes, inks, and/or plant extracts incorporated directly into the nanofibers are discussed with illustrations. The possibility to imprint patterns made of printing inks, plant parts (such as petals, leaves, and slices of rhizomes), and fungal growth on fruits with their faithful reproductions on the nanofiber mats is illustrated with suitable examples. Metabolites were identified by tandem mass spectrometry data available in the literature and in databases. The results highlight the significance of electrospun nanofiber mats as smart surfaces to capture diverse classes of compounds for rapid detection or to imprint imaging under ambient conditions. Large surface area, appropriate chemical functionalities exposed, and easiness of desorption due to weaker interactions of the analyte species are the specific advantages of nanofibers for this application. PMID:27159150

  8. Highly reproducible laser beam scanning device for an internal source laser desorption microprobe Fourier transform mass spectrometer

    NASA Astrophysics Data System (ADS)

    Scott, Jill R.; Tremblay, Paul L.

    2002-03-01

    Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (˜5 μm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ˜9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz's law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies.

  9. Aptamer Conjugated Multifunctional Nanoflowers as a Platform for Targeting, Capture and Detection in Laser Desorption Ionization Mass Spectrometry

    PubMed Central

    Ocsoy, Ismail; Gulbakan, Basri; Shukoor, Mohammed Ibrahim; Xiong, Xiangling; Chen, Tao; Powell, David H.; Tan, Weihong

    2013-01-01

    Although many different nanomaterials have been tested as substrates for laser desorption and ionization mass spectrometry (LDI-MS), this emerging field still requires more efficient multifuncional nanomaterials for targeting, enrichment and detection. Here, we report the use of gold-manganese oxide (Au@MnO) hybrid nanoflowers as an efficient matrix for LDI–MS. The nanoflowers were also functionalized with two different aptamers to target cancer cells and capture adenosine triphosphate (ATP), respectively. These nanoflowers were successfully used for metabolite extraction from cancer cell lysates. Thus, in one system, our multifunctional nanoflowers can 1) act as an ionization substrate for mass spectrometry, 2) target cancer cells, and 3) detect and analyze metabolites from cancer cells. PMID:23211039

  10. Vitamin D-metabolites from human plasma and mass spectrometric analysis by fast heavy ion induced desorption

    NASA Astrophysics Data System (ADS)

    Fohlman, J.; Peterson, P. A.; Kamensky, I.; Håkansson, P.; Sundqvist, B.

    1982-07-01

    D-vitamin metabolites have been isolated from human serum employing chromatographic techniques. The serum carrier protein for vitamin D (DBP) was first isolated by immunosorbent chromatography. Lipid ligands associated with DBP were then extracted with hexane and separated by high pressure liquid chromatography (HPLC). Detection of vitamin D metabolites by their absorbance of ultraviolet light is not sufficiently sensitive to monitor all vitamin D derivatives from a few millilitres of serum. Therefore, further analyses are necessary to quantitate these compounds. We have begun to develop a mass spectrometric method to achieve a reliable, quantitative procedure. As a first step towards this goal a number of pure samples of vitamin D compounds have been studied in a time-of-flight mass spectrometer based on fast heavy ion induced desorption. All vitamin D compounds examined could be detected and identified by their molecular ion and fragment spectra.

  11. Evaluation of desorption/ionization mass spectrometric methods in the forensic applications of the analysis of inks on paper.

    PubMed

    Grim, D M; Siegel, J; Allison, J

    2001-11-01

    Fast atom bombardment and laser desorption mass spectrometry (LDMS) provide molecular level information concerning an ink's composition. Two ink-jet printer inks, Ink A containing the cationic dye Methyl Violet 2B, and Ink B containing the anionic dye, Solvent Black, were studied. Both positive and negative ion detection modes of the mass spectrometer were used. LD may be used for the analysis of inks on paper. Once on paper, the ink's solvent system has evaporated, leaving mainly the dyes behind, which are detected using LDMS. An ink fades with time, indicating that the dyes are degrading. Preliminary results from an accelerated aging study of ballpoint pen ink using UV irradiation confirm that dye degradation products are formed. The degradation chemistry follows an oxidative demethylation process for which all products formed are detected using LDMS. Results suggest that LDMS may be developed to determine the relative age of inks. PMID:11714153

  12. Analysis of polycyclic aromatic hydrocarbons (PAHs) using nanosecond laser desorption/femtosecond ionization laser mass spectrometry (FLMS)

    NASA Astrophysics Data System (ADS)

    Robson, L.; Tasker, A. D.; Hankin, S. M.; Ledingham, K. W. D.; Singhal, R. P.; Fang, X.; McCanny, T.; Kosmidis, C.; Tzallas, P.; Langley, A. J.; Taday, P. F.; Divall, E. J.

    2001-08-01

    Nanosecond laser desorption/femtosecond ionization laser mass spectrometry (LD/FLMS) allows ultra-sensitive detection and trace analysis of atoms and molecules. In this study, we have applied the LD/FLMS technique to the characterization of polycyclic aromatic hydrocarbons (PAHs). Using high intensity femtosecond laser pulses (1013-1015 W/cm2) at λ˜395 nm and 790nm coupled to a reflectron time of flight mass spectrometer a series of PAHs have been investigated. In particular, anthracene, tetracene and pentacene are discussed. The spectra presented show intact parent ion at both wavelengths, with little fragmentation at lower ionization laser intensities. This initial data suggests that the optimum wavelength to operate FLMS for PAHs may be 395 nm and not 790 nm for maximum parent ion production. Comparative studies adopting nanosecond ionization are also discussed.

  13. Rapid analysis of animal drug residues by microcolumn solid-phase extraction and thermal desorption-ion trap mass spectrometry

    SciTech Connect

    Barshick, S.A.; Buchanan, M.V.

    1994-11-01

    A new approach was developed for the rapid and quantitative determination of an anthelmintic drug, phenothiazine, in milk. The technique involves a simple extraction procedure using a C{sub 18} microcolumn disc, followed by thermal desorption of the analyte from the disc directly into an ion trap mass spectrometer. The compounds are selectively ionized by isobutane chemical ionization and detected by tandem mass spectrometry. With this approach, 10 ppb detection limits were achieved with as little as 100 {mu}L mild and only 10 min of analysis time. This approach was used to analyze samples of milk taken from a cow administered a one-time therapeutic dose of phenothiazine. The target compound could be detected at 56 post-dosage, corresponding to a concentration of 30 ppb. 13 refs., 3 figs., 2 tabs.

  14. Methane ice photochemistry and kinetic study using laser desorption time-of-flight mass spectrometry at 20 K.

    PubMed

    Bossa, J-B; Paardekooper, D M; Isokoski, K; Linnartz, H

    2015-07-14

    The ice photochemistry of pure methane (CH4) is studied at 20 K upon VUV irradiation from a microwave discharge H2 flow lamp. Laser Desorption Post-Ionization Time-Of-Flight Mass Spectrometry (LDPI TOF-MS) is used for the first time to determine branching ratios of primary reactions leading to CH3, CH2, and CH radicals, typically for fluences as expected in space. This study is based on a stable end-products analysis and the mass spectra are interpreted using an appropriate set of coupled reactions and rate constants. This yields clearly different values from previous gas phase studies. The matrix environment as well as the higher efficiency of reverse reactions in the ice clearly favor CH3 radical formation as the main first generation photoproduct. PMID:26073296

  15. Characterization of humic substances by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Mugo, Samuel M; Bottaro, Christina S

    2004-01-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and laser desorption/ionization (LDI-)TOFMS have been used to characterize Suwannee River humic substances, obtained from the International Humic Substances Society (IHSS), and Armadale soil fulvic acid (ASFA). An array of MALDI matrices were tested for use with humic substances, including alpha-cyano-4-hydroxycinammic acid (CHCA), 2-(4-hydroxyphenylazo)benzoic acid (HABA), 2,5-dihydroxybenzoic acid (DHBA), sinapinic acid, dithranol and norharmane. DHBA yielded the best results, exhibiting superior ionization efficiency, low noise, broad applicability to the analytes of interest, and most importantly producing an abundance of high mass ions, the highest observed being m/z 1848. A number of sample preparation modes were investigated; the overlayer method improved sample/matrix homogeneity and hence shot-to-shot reproducibility. The choice of the matrix, mass ratio of analyte to matrix, and the sample preparation protocol, were found to be the most critical factors governing the quality of the mass spectra. Matrix suppression was greatly enhanced by ensuring good mixing of matrix and analyte in the solid phase, proper optimization of the matrix/analyte ratio, and optimizing delayed extraction to ensure complete matrix-analyte reaction in the plume before ions are moved to the flight tube. A number of common features, in particular specific ions which could not be attributed to the matrices or to contaminants, were present in the spectra of all the humic substances, regardless of origin or operational definition. Additionally, a prominent repeating pattern of peaks separated by 55, 114 and 169 Da was clearly observed in both LDI and MALDI, suggesting that the humic compounds studied here may have quasi-polymeric or oligomeric features. PMID:15386633

  16. A SIMPLE AND RAPID MATRIX-ASSISTED LASER DESORPTION/IONIZATION TIME OF FLIGHT MASS SPECTROMETRY METHOD TO SCREEN FISH PLASMA SAMPLES FOR ESTROGEN-RESPONSIVE BIOMARKERS

    EPA Science Inventory

    In this study, we describe and evaluate the performance of a simple and rapid mass spectral method for screening fish plasma for estrogen-responsive biomarkers using matrix assisted laster desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) couopled with a short...

  17. Laser desorption ionization mass spectrometry of peptides on a hybrid CHCA organic-inorganic matrix.

    PubMed

    Fleith, Clément; Cantel, Sonia; Subra, Gilles; Mehdi, Ahmad; Ciccione, Jeremie; Martinez, Jean; Enjalbal, Christine

    2014-08-01

    We report applications of new hybrid organic-inorganic silica based materials as laser desorption/ionization (LDI)-promoting surfaces for high-throughput identification of peptides. The driving force of our work was to design a new material composed of a conventional MALDI matrix covalently attached to silica with a high organic/inorganic ratio in order to improve the UV absorption by such LDI hybrid matrices. Amorphous CHCA-functionalized silica presenting an organic content up to 1.3 mmol g(-1) (around 40% in weight from TGA and elementary analysis measurements) gave very interesting LDI performances in terms of detection sensitivity as well as relative ionization discrepancy (spectral suppression) through the analyses of small synthetic peptide mixtures (550-1300 Da) taking CHCA and amorphous silica as model matrices for control experiments. PMID:24910856

  18. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    PubMed Central

    Aizikov, Konstantin; Smith, Donald F.; Chargin, David A.; Ivanov, Sergei; Lin, Tzu-Yung; Heeren, Ron M. A.; O’Connor, Peter B.

    2011-01-01

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in ∼1 × 10–8 mbar vacuum. The range of motion is set to 100 mm × 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The “oversampling” MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter. PMID:21639522

  19. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    SciTech Connect

    Aizikov, Konstantin; Lin, Tzu-Yung; Smith, Donald F.; Heeren, Ron M. A.; Chargin, David A.; Ivanov, Sergei; O'Connor, Peter B.

    2011-05-15

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in {approx}1 x 10{sup -8} mbar vacuum. The range of motion is set to 100 mm x 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The ''oversampling'' MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.

  20. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Mass Spectrometry (GALDI-FTMS)

    SciTech Connect

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; Jill R. Scott

    2008-07-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform mass spectrometer (FTMS) has been employed to determine how well bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition of C18H39O7Na . A natural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination was estimated to be 3 parts per trillion or ~7 zeptomoles per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTMS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  1. Thermally annealed gold nanoparticles for surface-assisted laser desorption ionisation-mass spectrometry of low molecular weight analytes.

    PubMed

    Pilolli, Rosa; Ditaranto, Nicoletta; Di Franco, Cinzia; Palmisano, Francesco; Cioffi, Nicola

    2012-10-01

    Metal nanomaterials have an emerging role in surface-assisted laser desorption ionisation-mass spectrometry (SALDI-MS) providing a useful tool to overcome some limitations intrinsically related to the use of conventional organic matrices in matrix-assisted LDI-MS. In this contribution, the possibility to use a stainless-steel-supported gold nanoparticle (AuNP) film as a versatile platform for SALDI-MS was assessed. A sacrificial anode electrosynthetic route was chosen in order to obtain morphologically controlled core-shell AuNPs; the colloidal AuNPs were, thereafter, drop cast onto a stainless-steel sample plate and the resulting AuNP film was thermally annealed in order to improve its effectiveness as LDI-MS promoter. Spectroscopic characterization of the nanostructured film by X-ray photoelectron spectroscopy was crucial for understanding how annealing induced changes in the surface chemistry and influenced the performance of AuNPs as desorption/ionisation promoter. In particular, it was demonstrated that the post-deposition treatments were essential to enhance the AuNP core/analyte interaction, thus resulting in SALDI-MS spectra of significantly improved quality. The AuNP films were applied to the detection of three different classes of low molecular weight (LMW) analytes, i.e. amino acids, peptides and LMW polymers, in order to demonstrate the versatility of this nanostructured material. PMID:22825677

  2. [Determination of volatile organic compounds in ambient air by thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry].

    PubMed

    Feng, Lili; Hu, Xiaofang; Yu, Xiaojuan; Zhang, Wenying

    2016-02-01

    A method was established for the simultaneous determination of 23 volatile organic compounds (VOCs) in ambient air with combination of thermal desorption (TD) and gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). The air samples were collected by active sampling method using Tenax-TA sorbent tubes, and desorbed by thermal desorption. The analytes were determined by GC-MS/MS in selected reaction monitoring (SRM) mode, and internal standard method was applied to quantify the VOCs. The results of all the 23 VOCs showed good linearities in low level (0. 01-1 ng) and high level (1-100 ng) with all the correlation coefficients (r2) more than 0. 99. The method quantification limits were between 0. 000 08-1 µg/m3. The method was validated by means of recovery experiments (n = 6) at three spiked levels of 2, 10 and 50 ng. The recoveries between 77% and 124% were generally obtained. The relative standard deviations (RSDs) in all cases were lower than 20%, except for chlorobenzene at the low spiked level. The developed method was applied to determine VOCs in ambient air collected at three sites in Shanghai. Several compounds, like benzene, toluene, ethylbenzene, m-xylenes, p-xylenes, styrene, 1, 2, 4-trimethylbenzene and hexachlorobutadiene were detected and confirmed in all the samples analyzed. The method is highly accurate, reliable and sensitive for monitoring the VOCs in ambient air. PMID:27382728

  3. Analysis of the volatile components emitted from cut tobacco processing by gas chromatography/mass spectrometry thermal desorption system.

    PubMed

    Gao, Qiang; Sha, Yunfei; Wu, Da; Liu, Baizhan; Chen, Chaoying; Fang, Dingye

    2012-11-15

    A sensitive and reliable method was developed for the determination of volatile components emitted from cut tobacco processing using thermal desorption (TD) followed by gas chromatography-mass spectrometry (GC-MS). In the work, to obtain the optimal sorbent, three commercial sorbents were compared in terms of adsorption efficiency. The carbotrap 349 was found to have the best performance. The desorption conditions were also studied. Validation of the TD-GC-MS method showed good sensibility, linearity and precision. Limits of detection ranges were from 0.20 to 3.6 ng. Calibration curves were obtained by plotting peak area versus concentration and the correlation coefficients relating to linearity were at least 0.9984. The analysis was reproducible, with relative standard deviation (n=8) within 6.5%. The target compound breakthrough examination showed no significant losses when about 1500 ng standards were prepared. In order to evaluate the performance of the analytical method in the volatile constituents of cut tobacco, samples were taken in industrial areas of cut tobacco processing. Recoveries ranged from 85.1% to 110% for all the compounds and good precision had been reached (RSD<13.3). The results proved that TD-GC-MS was a simple, rapid and accurate method for the analysis of volatile compounds emitted from cut tobacco drying step. PMID:23158312

  4. Headspace sorptive extraction for the analysis of organotin compounds using thermal desorption and gas chromatography with mass spectrometry.

    PubMed

    Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

    2013-03-01

    A method based on headspace sorptive extraction (HSSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed for the simultaneous determination of six organotin compounds (OTCs), corresponding to mono- and di-substituted methyltin, butyltin and octyltin species. Several parameters affecting both the headspace extraction and thermal desorption steps were carefully optimized using multivariate designs. Analytes were derivatized by in situ ethylation with sodium tetraethylborate. The optimized method was applied to the analysis of water samples of different origins, as well as to checking the migration of the studied compounds from commercially available plastic containers to the adequate liquid simulant. Quantification was carried out against aqueous calibration curves using diphenyltin as internal standard, providing detection limits of between 1.7 and 7.0 ng(Sn) L(-1), depending on the compound, and repeatabilities lower than 10% in terms of relative standard deviation. The applicability of the method was assessed by means of recovery studies and satisfactory values for all compounds were attained. The release of OTCs from the tested packages to the liquid simulant was confirmed, concentrations as high as 2.4 μg(Sn) L(-1) being found for dioctyltin. Even though the proposed method was developed for organotin halides, its application to an organotin ester shows its suitability for determining these compounds in migration assays. PMID:23357745

  5. Rapid characterization of chemical compounds in liquid and solid states using thermal desorption electrospray ionization mass spectrometry.

    PubMed

    Huang, Min-Zong; Zhou, Chi-Chang; Liu, De-Lin; Jhang, Siou-Sian; Cheng, Sy-Chyi; Shiea, Jentaie

    2013-10-01

    Rapid characterization of thermally stable chemical compounds in solid or liquid states is achieved through thermal desorption electrospray ionization mass spectrometry (TD-ESI/MS). A feature of this technique is that sampling, desorption, ionization, and mass spectrometric detection are four separate events with respect to time and location. A metal probe was used to sample analytes in their solid or liquid states. The probe was then inserted in a preheated oven to thermally desorb the analytes on the probe. The desorbed analytes were carried by a nitrogen gas stream into an ESI plume, where analyte ions were formed via interactions with charged solvent species generated in the ESI plume. The analyte ions were subsequently detected by a mass analyzer attached to the TD-ESI source. Quantification of acetaminophen in aqueous solutions using TD-ESI/MS was also performed in which a linear response for acetaminophen was obtained between 25 and 500 ppb (R(2) = 0.9978). The standard deviation for a reproducibility test for ten liquid samples was 9.6%. Since sample preparation for TD-ESI/MS is unnecessary, a typical analysis can be completed in less than 10 s. Analytes such as the active ingredients in over-the-counter drugs were rapidly characterized regardless of the different physical properties of said drugs, which included liquid eye drops, viscous cold syrup solution, ointment cream, and a drug tablet. This approach was also used to detect trace chemical compounds in illicit drugs and explosives, in which samples were obtained from the surfaces of a cell phone, piece of luggage made from hard plastic, business card, and wooden desk. PMID:24050317

  6. Chemometric optimization of a low-temperature plasma source design for ambient desorption/ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Albert, Anastasia; Engelhard, Carsten

    2015-03-01

    Low-temperature plasmas (LTPs) are attractive sources for atomic and molecular mass spectrometry (MS). In the past, the LTP probe, which was first described by Harper et al., was used successfully for direct molecular mass spectrometric analysis with minimal sample pretreatment in a variety of applications. Unfortunately, the desorption/ionization source itself is commercially not available and custom-built LTP set-ups with varying geometry and operational configurations were utilized in the past. In the present study, a rapid chemometrics approach based on systematic experiments and multivariate data analysis was used to optimize the LTP probe geometry and positioning relative to the atmospheric-pressure inlet of a mass spectrometer. Several parameters were studied including the probe geometry, electrode configuration, quartz tube dimensions, probe positioning and operating conditions. It was found that the plasma-to-MS-inlet distance, the plasma-to-sample-plate distance, and the angle between the latter are very important. Additional effects on the analytical performance were found for the outer electrode width, the positioning of the electrodes, the inner diameter of the quartz tube, the quartz wall thickness, and the gas flow. All experiments were performed using additional heating of the sample to enhance thermal desorption and maximize the signal (T = 150 °C). After software-assisted optimization, attractive detection limits were achieved (e.g., 1.8 × 10- 7 mol/L for 4-acetamidothiophenol). Moreover, relative standard deviation (RSD) improved from values of up to 30% before optimization to < 15% RSD after the procedure was completed. This chemometrics approach for method optimization is not limited to LTP-MS and considered to be attractive for other plasma-based instrumentation as well.

  7. Characterization of antibody-antigen interactions: comparison between surface plasmon resonance measurements and high-mass matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Bich, Claudia; Scott, Mike; Panagiotidis, Andreas; Wenzel, Ryan J; Nazabal, Alexis; Zenobi, Renato

    2008-04-01

    The interaction between the bovine prion protein (bPrP) and a monoclonal antibody, 1E5, was studied with high-mass matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and surface plasmon resonance (SPR). In the case of MS a cross-linking stabilization was used prior to the analysis, whereas for SPR the antibody was immobilized and bPrP was injected. We compared the determination of parameters such as the epitope, the kinetics and binding strength, and the capacity of the antigen to bind two different antibodies. The two methods are highly complementary. SPR measurements require a lower amount of sample but are more time-consuming due to all of the necessary side steps (e.g., immobilization, regeneration). High-mass MALDI MS needs a higher overall amount of sample and cannot give direct access to the kinetic constants, but the analysis is faster and easier compared with SPR. PMID:18078803

  8. Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric study of bis(imidazole-1-carboxylate) endfunctionalized polymers,.

    PubMed

    Kéki, Sándor; Nagy, Miklós; Deák, György; Zsuga, Miklós; Herczegh, Pál

    2003-02-01

    A detailed Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric (MALDI-TOF MS) investigation of polyethylene glycol (PEG), polypropylene glycol (PPG) and polyisobutylene (PIB) bis(imidazole-1-carboxylate) esters is reported. The MS spectra of PPG and PIBb is (imidazole-1-carboxylate) esters recorded in the reflectron mode showed the presence of two additional series of peaks compared to those recorded in the linear mode, while in the case of PEG bis(imidazole-1-carboxylate) only one additional peak series appeared in the reflectron MS spectra. These additional series were attributed to the formation of fragment ions by the loss of one and two end groups in the first field-free region of the instrument. The neutral losses for the three polymers were also supported by using the post-source decay method (PSD). The observation of decreasing mass difference between the adjacent peaks from two series of polymeric ions with the increase of oligomer mass indicates the presence of PSD ions in a reflectron MALDI spectrum. The relationship between the mass of the precursor ions and those of the PSD ions and neutral loss are also discussed. PMID:12596703

  9. Principles of hydrogen radical mediated peptide/protein fragmentation during matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Asakawa, Daiki

    2016-07-01

    Matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) is a very easy way to obtain large sequence tags and, thereby, reliable identification of peptides and proteins. Recently discovered new matrices have enhanced the MALDI-ISD yield and opened new research avenues. The use of reducing and oxidizing matrices for MALDI-ISD of peptides and proteins favors the production of fragmentation pathways involving "hydrogen-abundant" and "hydrogen-deficient" radical precursors, respectively. Since an oxidizing matrix provides information on peptide/protein sequences complementary to that obtained with a reducing matrix, MALDI-ISD employing both reducing and oxidizing matrices is a potentially useful strategy for de novo peptide sequencing. Moreover, a pseudo-MS(3) method provides sequence information about N- and C-terminus extremities in proteins and allows N- and C-terminal side fragments to be discriminated within the complex MALDI-ISD mass spectrum. The combination of high mass resolution of a Fourier transform-ion cyclotron resonance (FTICR) analyzer and the software suitable for MALDI-ISD facilitates the interpretation of MALDI-ISD mass spectra. A deeper understanding of the MALDI-ISD process is necessary to fully exploit this method. Thus, this review focuses first on the mechanisms underlying MALDI-ISD processes, followed by a discussion of MALDI-ISD applications in the field of proteomics. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:535-556, 2016. PMID:25286767

  10. Desorption electrospray ionization-high resolution mass spectrometry for the screening of veterinary drugs in cross-contaminated feedstuffs.

    PubMed

    Seró, Raquel; Núñez, Oscar; Bosch, Jaume; Grases, José M; Rodríguez, Pilar; Moyano, Encarnacion; Galceran, Martia Teresa

    2015-09-01

    In this study, a desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) screening method was developed for fast identification of veterinary drugs in cross-contaminated feedstuffs. The reliable detection was performed working at high resolution (70,000 full width half maximum, FWHM) using an orbitrap mass analyzer. Among the optimized DESI parameters, the solvent (acetonitrile/water, 80:20, v/v) and the sample substrate (poly-tetrafluoroethylene, PTFE) were critical to obtain the best sensitivity. To analyze the solid feed samples, different approaches were tested and a simple solid-liquid extraction and the direct analysis of an aliquot (2 μL) of the extract after letting it dry on the PTFE printed spot provided the best results. The identification of the veterinary drugs (target and non-target) in the cross-contaminated feedstuffs based on the accurate mass measurement and the isotopic pattern fit was performed automatically using a custom-made database. The positive cross-contaminated feed samples were quantified by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The results obtained demonstrate that DESI-HRMS can be proposed as a fast and suitable screening method to identify positive cross-contaminated feedstuffs reducing the number of samples to be subsequently quantified by UHPLC-MS/MS, thus improving the productivity in quality control laboratories. PMID:26168975

  11. Recent Advances in Bacteria Identification by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Using Nanomaterials as Affinity Probes

    PubMed Central

    Chiu, Tai-Chia

    2014-01-01

    Identifying trace amounts of bacteria rapidly, accurately, selectively, and with high sensitivity is important to ensuring the safety of food and diagnosing infectious bacterial diseases. Microbial diseases constitute the major cause of death in many developing and developed countries of the world. The early detection of pathogenic bacteria is crucial in preventing, treating, and containing the spread of infections, and there is an urgent requirement for sensitive, specific, and accurate diagnostic tests. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an extremely selective and sensitive analytical tool that can be used to characterize different species of pathogenic bacteria. Various functionalized or unmodified nanomaterials can be used as affinity probes to capture and concentrate microorganisms. Recent developments in bacterial detection using nanomaterials-assisted MALDI-MS approaches are highlighted in this article. A comprehensive table listing MALDI-MS approaches for identifying pathogenic bacteria, categorized by the nanomaterials used, is provided. PMID:24786089

  12. Matrix assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) for direct visualization of plant metabolites in situ

    DOE PAGESBeta

    Sturtevant, Drew; Lee, Young -Jin; Chapman, Kent D.

    2015-11-22

    Direct visualization of plant tissues by matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has revealed key insights into the localization of metabolites in situ. Recent efforts have determined the spatial distribution of primary and secondary metabolites in plant tissues and cells. Strategies have been applied in many areas of metabolism including isotope flux analyses, plant interactions, and transcriptional regulation of metabolite accumulation. Technological advances have pushed achievable spatial resolution to subcellular levels and increased instrument sensitivity by several orders of magnitude. Furthermore, it is anticipated that MALDI-MSI and other MSI approaches will bring a new level of understanding tomore » metabolomics as scientists will be encouraged to consider spatial heterogeneity of metabolites in descriptions of metabolic pathway regulation.« less

  13. 5-Methoxysalicylic Acid Matrix for Ganglioside Analysis with Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Lee, Dongkun; Cha, Sangwon

    2015-03-01

    In this note, we report that high quality ganglioside profiles with minimal loss of sialic acid residues can be obtained in the positive ion mode by using a 5-methoxysalicylic acid (MSA) matrix for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Our results showed that MSA produced much less sialic acid losses from gangliosides than DHB, although MSA and DHB are differ only by their functional groups at their 5-positions (-OH for DHB and -OCH3 for MSA). Furthermore, our data also demonstrated that addition of an alkali metal additive was effective for simplifying ganglioside profiles, but not necessary for stabilizing glycosidic bonds of gangliosides if MSA was used as a matrix. This suggests that MALDI MS with MSA has a potential to gain additional benefits from the positive-ion mode analyses without losing performance in ganglioside profiling.

  14. Screening of the Binding of Small Molecules to Proteins by Desorption Electrospray Ionization Mass Spectrometry Combined with Protein Microarray

    NASA Astrophysics Data System (ADS)

    Yao, Chenxi; Wang, Tao; Zhang, Buqing; He, Dacheng; Na, Na; Ouyang, Jin

    2015-11-01

    The interaction between bioactive small molecule ligands and proteins is one of the important research areas in proteomics. Herein, a simple and rapid method is established to screen small ligands that bind to proteins. We designed an agarose slide to immobilize different proteins. The protein microarrays were allowed to interact with different small ligands, and after washing, the microarrays were screened by desorption electrospray ionization mass spectrometry (DESI MS). This method can be applied to screen specific protein binding ligands and was shown for seven proteins and 34 known ligands for these proteins. In addition, a high-throughput screening was achieved, with the analysis requiring approximately 4 s for one sample spot. We then applied this method to determine the binding between the important protein matrix metalloproteinase-9 (MMP-9) and 88 small compounds. The molecular docking results confirmed the MS results, demonstrating that this method is suitable for the rapid and accurate screening of ligands binding to proteins.

  15. Matrix assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) for direct visualization of plant metabolites in situ.

    PubMed

    Sturtevant, Drew; Lee, Young-Jin; Chapman, Kent D

    2016-02-01

    Direct visualization of plant tissues by matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has revealed key insights into the localization of metabolites in situ. Recent efforts have determined the spatial distribution of primary and secondary metabolites in plant tissues and cells. Strategies have been applied in many areas of metabolism including isotope flux analyses, plant interactions, and transcriptional regulation of metabolite accumulation. Technological advances have pushed achievable spatial resolution to subcellular levels and increased instrument sensitivity by several orders of magnitude. It is anticipated that MALDI-MSI and other MSI approaches will bring a new level of understanding to metabolomics as scientists will be encouraged to consider spatial heterogeneity of metabolites in descriptions of metabolic pathway regulation. PMID:26613199

  16. Detection of Posaconazole by Surface-Assisted Laser Desorption/Ionization Mass Spectrometry with Dispersive Liquid-Liquid Microextraction

    NASA Astrophysics Data System (ADS)

    Lin, Sheng-Yu; Chen, Pin-Shiuan; Chang, Sarah Y.

    2015-03-01

    A simple, rapid, and sensitive method for the detection of posaconazole using dispersive liquid-liquid microextraction (DLLME) coupled to surface-assisted laser desorption/ionization mass spectrometric detection (SALDI/MS) was developed. After the DLLME, posaconazole was detected using SALDI/MS with colloidal gold and α-cyano-4-hydroxycinnamic acid (CHCA) as the co-matrix. Under optimal extraction and detection conditions, the calibration curve, which ranged from 1.0 to 100.0 nM for posaconazole, was observed to be linear. The limit of detection (LOD) at a signal-to-noise ratio of 3 was 0.3 nM for posaconazole. This novel method was successfully applied to the determination of posaconazole in human urine samples.

  17. Analysis and Quantitation of Glycated Hemoglobin by Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hattan, Stephen J.; Parker, Kenneth C.; Vestal, Marvin L.; Yang, Jane Y.; Herold, David A.; Duncan, Mark W.

    2016-03-01

    Measurement of glycated hemoglobin is widely used for the diagnosis and monitoring of diabetes mellitus. Matrix assisted laser desorption/ionization (MALDI) time of flight (TOF) mass spectrometry (MS) analysis of patient samples is used to demonstrate a method for quantitation of total glycation on the β-subunit of hemoglobin. The approach is accurate and calibrated with commercially available reference materials. Measurements were linear (R2 > 0.99) across the clinically relevant range of 4% to 20% glycation with coefficients of variation of ≤ 2.5%. Additional and independent measurements of glycation of the α-subunit of hemoglobin are used to validate β-subunit glycation measurements and distinguish hemoglobin variants. Results obtained by MALDI-TOF MS were compared with those obtained in a clinical laboratory using validated HPLC methodology. MALDI-TOF MS sample preparation was minimal and analysis times were rapid making the method an attractive alternative to methodologies currently in practice.

  18. On plate graphite supported sample processing for simultaneous lipid and protein identification by matrix assisted laser desorption ionization mass spectrometry.

    PubMed

    Calvano, Cosima Damiana; van der Werf, Inez Dorothé; Sabbatini, Luigia; Palmisano, Francesco

    2015-05-01

    The simultaneous identification of lipids and proteins by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) after direct on-plate processing of micro-samples supported on colloidal graphite is demonstrated. Taking advantages of large surface area and thermal conductivity, graphite provided an ideal substrate for on-plate proteolysis and lipid extraction. Indeed proteins could be efficiently digested on-plate within 15 min, providing sequence coverages comparable to those obtained by conventional in-solution overnight digestion. Interestingly, detection of hydrophilic phosphorylated peptides could be easily achieved without any further enrichment step. Furthermore, lipids could be simultaneously extracted/identified without any additional treatment/processing step as demonstrated for model complex samples such as milk and egg. The present approach is simple, efficient, of large applicability and offers great promise for protein and lipid identification in very small samples. PMID:25770620

  19. Rapid screening of illicit additives in weight loss dietary supplements with desorption corona beam ionisation (DCBI) mass spectrometry.

    PubMed

    Wang, H; Wu, Y; Zhao, Y; Sun, W; Ding, L; Guo, B; Chen, B

    2012-08-01

    Desorption corona beam ionisation (DCBI), the relatively novel ambient mass spectrometry (MS) technique, was utilised to screen for illicit additives in weight-loss food. The five usually abused chemicals - fenfluramine, N-di-desmethyl sibutramine, N-mono-desmethyl sibutramine, sibutramine and phenolphthalein - were detected with the proposed DCBI-MS method. Fast single-sample and high-throughput analysis was demonstrated. Semi-quantification was accomplished based on peak areas in the ion chromatograms. Four illicit additives were identified and semi-quantified in commercial samples. As there was no tedious sample pre-treatment compared with conventional HPLC methods, high-throughput analysis was achieved with DCBI. The results proved that DCBI-MS is a powerful tool for the rapid screening of illicit additives in weight-loss dietary supplements. PMID:22784191

  20. Developments and Applications of Electrophoresis and Small Molecule Laser Desorption Ionization Mass Spectrometry

    SciTech Connect

    Zhang, Hui

    2007-01-01

    Ultra-sensitive native fluorescence detection of proteins with miniaturized one- and two-dimensional polyacrylamide gel electrophoresis was achieved with laser side-entry excitation, which provides both high excitation power and low background level. The detection limit for R-phycoerythrin protein spots in 1-D SDS-PAGE was as low as 15 fg, which corresponds to 40 thousand molecules only. The average detection limit of six standard native proteins was 5 pg per band and the dynamic range spanned more than 3 orders of magnitude. Approximately 150 protein spots from 30 ng of total Escherichia coli extraction were detected on a 0.8 cm x 1 cm gel in two-dimensional separation. Estrogen-DNA adducts as 4-OHE1(E2)-1-N3Ade and 4-OHEI(E2)-2-NacCys were hypothesized as early risk assessment of prostate and breast cancers. Capillary electrophoresis, luminescence/absorption spectroscopy and LC-MS were used to characterize and detect these adducts. Monoclonal antibodies against each individual adduct were developed and used to enrich such compounds from urine samples of prostate and breast cancer patients as well as healthy people. Adduct 4-OHE1-1-N3Ade was detected at much higher level in urine from subjects with prostate cancer patients compared to healthy males. The same adduct and 4-OHEI-2-NacCys were also detected at a much higher level in urine from a woman with breast carcinoma than samples from healthy controls. These two DNA adducts may serve as novel biomarkers for early diagnostic of cancers. The adsorption properties of R-phycoerythrin (RPE), on the fused-silica surface were studied using capillary electrophoresis (CE) and single molecule spectroscopy. The band shapes and migration times were measured in CE. Adsorption and desorption events were recorded at the single-molecule level by imaging of the evanescent-field layer using total internal reflection. The adsorbed RPE molecules on the fused-silica prism surface were

  1. Analysis of Polycyclic Aromatic Hydrocarbons Using Desorption Atmospheric Pressure Chemical Ionization Coupled to a Portable Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Jjunju, Fred P. M.; Maher, Simon; Li, Anyin; Badu-Tawiah, Abraham K.; Taylor, Stephen; Graham Cooks, R.

    2015-02-01

    Desorption atmospheric pressure chemical ionization (DAPCI) is implemented on a portable mass spectrometer and applied to the direct detection of polycyclic aromatic hydrocarbons (PAHs) and alkyl substituted benzenes. The presence of these compounds in the environment poses a significant threat to the health of both humans and wildlife because of their carcinogenic, toxic, and mutagenic properties. As such, instant detection outside of the laboratory is of particular importance to allow in-situ measurement at the source. Using a rapid, high throughput, miniature, handheld mass spectrometer, several alkyl substituted benzenes and PAHs (i.e., 1,2,3,5-tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, fluoranthene, anthracene, benzo[ k]fluoranthene, dibenz[ a,h]anthracene, acenaphthene, indeno[1,2,3-c,d]pyrene, 9-ethylfluorene, and 1-benzyl-3-methyl-naphthalene) were identified and characterized using tandem mass spectrometry (MS/MS) from ambient surfaces, in the open air. This method can provide almost instantaneous information while minimizing sample preparation, which is advantageous in terms of both cost and simplicity of analysis. This MS-based technique is applicable to a wide range of environmental organic molecules.

  2. Laser Desorption/Ionization Mass Spectrometry (LDI-MS) of Lipids with Iron Oxide Nanoparticle-Coated Targets.

    PubMed

    Kusano, Maiko; Kawabata, Shin-Ichirou; Tamura, Yusuke; Mizoguchi, Daigou; Murouchi, Masato; Kawasaki, Hideya; Arakawa, Ryuichi; Tanaka, Koichi

    2014-01-01

    Iron oxide nanoparticle (NP)-coated target plates were employed for the direct detection and analysis of low molecular weight lipids by laser desorption/ionization (LDI) mass spectrometry (MS). We have demonstrated that the use of the iron oxide NP-coated target provides a simple, direct, and rapid detection method for lipid standards and epidermal surface lipids without any cumbersome sample pretreatment as well as mass spectra that are free of background matrix peaks. Lipid standards (1-stearoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-sn-glycerol, 1-palmitoyl-2-oleoyl-3-linoleoyl-rac-glycerol, 1,2-distearoyl-sn-glycero-3-phosphocholine) were detected as either protonated or cationated species. Clean MS/MS spectra for each lipid were also successfully obtained. Pre-MS surface cleaning of the target plates with UV-ozone treatment successfully removed organic contaminants that would interfere with the mass spectra especially in the low molecular weight region. Preliminary application of the presented target plate to the detection of endogenous lipids in latent fingerprints showed promising results and for potential use in the visualization and chemical composition determination of latent fingerprints by nanoparticle assistance. PMID:24860715

  3. Improved procedure for dendrimer-based mass calibration in matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry.

    PubMed

    Gross, Jürgen H

    2016-08-01

    A procedure is described that results in a substantial increase in signal intensity and in improved accuracy of positive-ion mass calibration when using commercially available kits of monodisperse dendrimers (SpheriCal(®)) in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The peak intensities are amplified by an admixture of 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene] malononitrile (DCTB) matrix to the kits comprising of 9-nitroanthracene matrix, sodium trifluoroacetate, and four dendrimers. Boosted ion formation then permits lower laser fluence to be used and thus yields enhanced mass resolution. Further, the number of reference peaks is doubled by doping the sample preparation with cesium ions. This results in four [M+Cs](+) ion signals in addition to four [M+Na](+) ion signals provided by the standard kit. Overall, the modified procedure notably reduces the consumption of the expensive calibration standard kits, while it increases mass resolution and enables the use of an advanced calibration algorithm requiring at least six reference peaks. Graphical abstract A dendrimer-based mass calibration for MALDI-TOF-MS can be improved by adding a DCTB matrix and doping the sample preparation with Cs(+) ions. Having eight rather than just four reference peaks reduces the average mass error of the calibration curve about fivefold. PMID:27317254

  4. Atmospheric pressure-thermal desorption (AP-TD)/electrospray ionization-mass spectrometry for the rapid analysis of Bacillus spores.

    PubMed

    Basile, Franco; Zhang, Shaofeng; Shin, Yong-Seung; Drolet, Barbara

    2010-04-01

    A technique is described where an atmospheric pressure-thermal desorption (AP-TD) device and electrospray ionization (ESI)-mass spectrometry (MS) are coupled and used for the rapid analysis of Bacillus subtilis spores in complex matrices. The resulting AP-TD/ESI-MS technique combines the generation of volatile compounds and/or pyrolysis products with soft-ionization MS detection. In the AP-TD/ESI-MS approach, an electrospray solvent plume was used as the ionization vehicle of thermally desorbed neutrals at atmospheric pressure prior to mass spectrometric analysis using a quadrupole ion trap mass spectrometer. The approach is quantitative with the volatile standard dimethyl methylphosphonate (DMMP) and with the use of an internal standard (diethyl methylphosphonate, DEMP). A linear response was obtained as tested in the 1-50 ppm range (R(2) = 0.991) with a standard error of the estimate of 0.193 (0.9% RSD, n = 5). Bacterial spores were detected by performing pyrolysis in situ methylation with the reagent tetramethylammonium hydroxide (TMAH) for the detection of the bacterial spore biomarker dipicolinic acid (DPA) as the dimethylated derivative (2Me-DPA). This approach allowed spore detection even in the presence of growth media in crude lyophilized samples. Repetitive analyses could be performed with a duty cycle of less than 5 min total analysis time (including sample loading, heating and data acquisition). This strategy proved successful over other direct ambient MS approaches like DESI-MS and AP-TD/ESI-MS without the in situ derivatization step to detect the dipicolinic acid biomarker from spores. A detection limit for the dimethylated DPA biomarker was estimated at 1 ppm (equivalent to 0.01 mug of DPA deposited in the thermal desorption tube), which corresponded to a calculated detection limit of 10(5) spores deposited or 0.1% by weight spore composition in solid samples (assuming a 1 mg sample size). The AP-TD/ESI source used in conjunction with the in situ

  5. Matrix-assisted laser desorption/ionization directed nano-electrospray ionization tandem mass spectrometric analysis for protein identification.

    PubMed

    Kast, Juergen; Parker, Carol E; van der Drift, Koen; Dial, J Michael; Milgram, Sharon L; Wilm, Matthias; Howell, Michael; Borchers, Christoph H

    2003-01-01

    In those cases where the information obtained by peptide mass fingerprinting or matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS) is not sufficient for unambiguous protein identification, nano-electrospray ionization (nano-ESI) and/or electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis must be performed. The sensitivity of nano-ESI/MS, however, is lower than that of MALDI-MS, especially at very low analyte concentrations and/or in the presence of contaminants, such as salt and detergents. Moreover, to perform ESI-MS/MS, the peptide masses of the precursor ions must be known. The approach described in this paper, MALDI-directed nano-ESI-MS/MS, makes use of information obtained from the more sensitive MALDI-MS experiments in order to direct subsequent nano-ESI-MS/MS experiments. Peptide molecular ions found in the MALDI-MS analysis are then selected, as their (+2) precursor ions, for nano-ESI-MS/MS sequencing, even though these ions cannot be detected in the ESI-MS spectra. This method, originally proposed by Tempst et al. (Anal. Chem. 2000, 72: 777-790), has been extended to provide better sensitivity and shorter analysis times; also, a comparison with liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been performed. These experiments, performed using quadrupole time-of-flight instruments equipped with commercially available nano-ESI sources, have allowed the unambiguous identification of in-gel digested proteins at levels below their ESI-MS detection limits, even in the presence of salts and detergents. PMID:12876682

  6. Raman spectroscopy and laser desorption mass spectrometry for minimal destructive forensic analysis of black and color inkjet printed documents.

    PubMed

    Heudt, Laetitia; Debois, Delphine; Zimmerman, Tyler A; Köhler, Laurent; Bano, Fouzia; Partouche, Franck; Duwez, Anne-Sophie; Gilbert, Bernard; De Pauw, Edwin

    2012-06-10

    Inkjet ink analysis is the best way to discriminate between printed documents, or even though more difficult, to connect an inkjet printed document with a brand or model of printers. Raman spectroscopy and laser desorption mass spectrometry (LDMS) have been demonstrated as powerful tools for dyes and pigments analysis, which are ink components. The aim of this work is to evaluate the aforementioned techniques for inkjet inks analysis in terms of discriminating power, information quality, and nondestructive capability. So, we investigated 10 different inkjet ink cartridges (primary colors and black), 7 from the HP manufacturer and one each from Epson, Canon and Lexmark. This paper demonstrates the capabilities of three methods: Raman spectroscopy, LDMS and MALDI-MS. Raman spectroscopy, as it is preferable to try the nondestructive approach first, is successfully adapted to the analysis of color printed documents in most cases. For analysis of color inkjet inks by LDMS, we show that a MALDI matrix (9-aminoacridine, 9AA) is needed to desorb and to ionize dyes from most inkjet inks (except Epson inks). Therefore, a method was developed to apply the 9AA MALDI matrix directly onto the piece of paper while avoiding analyte spreading. The obtained mass spectra are very discriminating and lead to information about ink additives and paper compositions. Discrimination of black inkjet printed documents is more difficult because of the common use of carbon black as the principal pigment. We show for the first time the possibility to discriminate between two black-printed documents coming from different, as well as from the same, manufacturers. Mass spectra recorded from black inks in positive ion mode LDMS detect polyethylene glycol polymers which have characteristic mass distributions and end groups. Moreover, software has been developed for rapid and objective comparison of the low mass range of these positive mode LDMS spectra which have characteristic unknown peaks. PMID

  7. Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment

    ERIC Educational Resources Information Center

    Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

    2011-01-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

  8. THE USE OF MATRIX-ASSISTED LASER DESORPTION/IONIZATION-MASS SPECTROMETRY FOR THE IDENTIFICATION OF AEROMONAS ISOLATES OBTAINED FROM WATER DISTRIBUTION SYSTEMS

    EPA Science Inventory

    Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has long been established as a tool by which microorganisms can be characterized and identified. EPA is investigating the potential of using this technology as a way to rapidly identify Aeromonas species fo...

  9. Determination of off-flavor compounds, 2-methylisoborneol and geosmin, in salmon fillets using stir bar sorptive extraction–thermal desorption coupled with gas chromatography–mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction -thermal desorption coupled with gas chromatography -mass spectrometry (SBSE -TD -GCMS). M...

  10. Enzymatic digestion on the sample foil as a method for sequence determination by plasma desorption mass spectrometry: the primary structure of porpoise relaxin

    NASA Astrophysics Data System (ADS)

    Woods, Amina S.; Cotter, Robert J.; Yoshioka, Motoi; Büllesbach, Erika; Schwabe, Christian

    1991-12-01

    Plasma desorption mass spectrometry (PDMS) was used to determine the C-terminus of the B-chain porpoise relaxin, a polypeptide hormone having three dimensional and disulfide homology with insulin. Trypsin was used to generate a series of peptide fragments for mapping by PDMS. The C-terminal fragments were purified and their sequences determined by on-foil digestion with carboxypeptidase Y.

  11. Signal and Charge Enhancement for Protein Analysis by Liquid Chromatography-Mass Spectrometry with Desorption Electrospray Ionization

    PubMed Central

    Liu, Yan; Miao, Zhixin; Lakshmanan, Rajeswari; Ogorzalek Loo, Rachel R.; Loo, Joseph A.; Chen, Hao

    2015-01-01

    We recently reported the use of desorption electrospray ionization (DESI) as a novel interface to couple high-performance liquid chromatography (HPLC) with mass spectrometry (MS) (Chem. Commun. 2011, 47, 4171). One of the benefits of such an interface is that post-column derivatization of separated analytes can be integrated with ionization via a “reactive” DESI approach in which a derivatizing reagent is doped into the spray solvent. The reactive DESI interface allows analyte desorption/ionization from the end of the chromatographic column with prompt MS detection; a short time delay of ~20 ms was demonstrated. In this study, we extended this application by “supercharging” proteins following HPLC separation using a DESI spray solvent containing supercharging reagents, m-nitrobenzyl alcohol (m-NBA) or sulfolane. Proteins (insulin, ubiquitin, lysozyme and α-lactalbumin) eluted out of the LC column can be supercharged with the protein charge state distributions (CSDs) significantly increased (to higher charge), which would be advantageous for subsequent top-down MS analysis of proteins. Interestingly, supercharging combined with reactive DESI enhances tolerance towards trifluoroacetic acid (TFA), which is known to be a superior additive in the mobile phase for premium peptide/protein chromatographic separation but has severe signal suppression effects for conventional electrospray ionization (ESI). In comparison to electrosonic spray ionization (ESSI), a variant form of ESI, the sensitivity of protein analysis using LC/DESI-MS with the mobile phase containing TFA can be improved by up to 70-fold for lysozyme and α-lactalbumin by including m-NBA in the DESI spray solvent. Presumably, by reducing TFA dissociation in the droplet, supercharging agents lower trifluoroacetate anion concentrations and concomitantly reduce ion pairing to analyte cationic sites. The reduced ion pairing therefore decreases the TFA signal suppression effect. The supercharging

  12. Detection of Biosignatures in Natural and Microbial Cultured Jarosites Using Laser- Desorption Fourier Transform Mass Spectrometry: Implications for Astrobiology

    NASA Astrophysics Data System (ADS)

    Kotler, J.; Hinman, N. W.; Yan, B.; Stoner, D. L.; Scott, J. R.

    2006-12-01

    The jarosite group minerals have received increasing attention since the discovery by the Mars Exploration Rover-Opportunity of jarosite on the Martian surface. The general chemical formula for jarosite is XFe3(SO4)2(OH)6 where the X represents both monovalent and divalent cations that can occupy the axial positions in the crystal structure. Commonly found ions include K+, Na+, H3O+, NH4+, and Pb2+ with reports of other large ions occupying this position in the literature. Modeling efforts have been performed to confirm that jarosite has the ability to incorporate a variety of "foreign" cations. The minerals unique ability to incorporate various large ions in its structure and its association with biological activity in terrestrial environments has lead to investigations regarding its use as an indicator of aqueous and/or biological activity. The use of laser desorption Fourier transform mass spectrometry (LD-FTMS) has revealed the presence of organic matter including the amino acid, glycine, in several jarosite samples from various worldwide locations. Iron precipitates derived from acidophilic microbial cultures were also analyzed. Using attenuated total reflectance infrared spectroscopy (ATR-IR), signals indicative of microbes or microbial exudates were weak and ambiguous. In contrast, LD-FTMS clearly detected bioorganic constituents in some desorption spots. However, the signals were sporadic and required the laser scanning/imaging capability of our laboratory built system to locate the microbial signatures in the heterogeneous samples. The ability to observe these bioorganic signatures in jarosite samples using the instrumental technique employed in this study furthers the goals of planetary geologists to determine whether signs of life (e.g., presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  13. Microfluidic Chip Coupled with Thermal Desorption Atmospheric Pressure Ionization Mass Spectrometry

    PubMed Central

    Chang, Chia-Hsien; Chen, Tsung-Yi; Chen, Yu-Chie

    2014-01-01

    Microfluidic chips have been used as platforms for a diversity of research purposes such as for separation and micro-reaction. One of the suitable detectors for microfluidic chip is mass spectrometry. Because microfluidic chips are generally operated in an open air condition, mass spectrometry coupled with atmospheric pressure ion sources can suit the requirement with minimum compromise. In this study, we develop a new interface to couple a microfluidic chip with mass spectrometry. A capillary tip coated with a layer of graphite, capable of absorbing energy of near-infrared (NIR) light is used to interface microfluidic chip with mass spectrometry. An NIR laser diode (λ=808 nm) is used to irradiate the capillary tip for assisting the generation of spray from the eluent of the microfluidic chip. An electrospray is provided to fuse with the spray generated from the microfluidic chip for post-ionization. Transesterification is used as the example to demonstrate the feasibility of using this interface to couple microfluidic chip with mass spectrometry. PMID:26839753

  14. Desorption/Ionization Fluence Thresholds and Improved Mass Spectral Consistency Measured Using a Flattop Laser Profile in the Bioaerosol Mass Spectrometry of Single Bacillus Endospores

    SciTech Connect

    Steele, P T; Srivastava, A; Pitesky, M E; Fergenson, D P; Tobias, H J; Gard, E E; Frank, M

    2004-11-30

    Bioaerosol mass spectrometry (BAMS) is being developed to analyze and identify biological aerosols in real-time. Mass spectra of individual Bacillus endospores were measured here with a bipolar aerosol time-of-flight mass spectrometer in which molecular desorption and ionization were produced using a single laser pulse from a Q-switched, frequency-quadrupled Nd:YAG laser that was modified to have an approximately flattop profile. The flattened laser profile allowed the minimum fluence required to desorb and ionize significant numbers of ions from single aerosol particles to be determined. For Bacillus spores this threshold had a mean value of approximately 1 nJ/{micro}m{sup 2} (0.1 J/cm{sup 2}). Thresholds for individual spores, however, could apparently deviate by 20% or more from the mean. Threshold distributions for clumps of MS2 bacteriophage and bovine serum albumin were subsequently determined. Finally, the flattened profile was observed to increase the reproducibility of single spore mass spectra. This is consistent with the general conclusions of our earlier paper on the fluence dependence of single spore mass spectra and is particularly significant because it is expected to enable more robust differentiation and identification of single bioaerosol particles.

  15. High-Spatial and High-Mass Resolution Imaging of Surface Metabolites of Arabidopsis thaliana by Laser Desorption-Ionization Mass Spectrometry Using Colloidal Silver

    SciTech Connect

    Jun, Ji Hyun; Song, Zhihong; Liu, Zhenjiu; Nikolau, Basil J.; Yeung, Edward S.; and Lee, Young Jin

    2010-03-17

    High-spatial resolution and high-mass resolution techniques are developed and adopted for the mass spectrometric imaging of epicuticular lipids on the surface of Arabidopsis thaliana. Single cell level spatial resolution of {approx}12 {micro}m was achieved by reducing the laser beam size by using an optical fiber with 25 {micro}m core diameter in a vacuum matrix-assisted laser desorption ionization-linear ion trap (vMALDI-LTQ) mass spectrometer and improved matrix application using an oscillating capillary nebulizer. Fine chemical images of a whole flower were visualized in this high spatial resolution showing substructure of an anther and single pollen grains at the stigma and anthers. The LTQ-Orbitrap with a MALDI ion source was adopted to achieve MS imaging in high mass resolution. Specifically, isobaric silver ion adducts of C29 alkane (m/z 515.3741) and C28 aldehyde (m/z 515.3377), indistinguishable in low-resolution LTQ, can now be clearly distinguished and their chemical images could be separately constructed. In the application to roots, the high spatial resolution allowed molecular MS imaging of secondary roots and the high mass resolution allowed direct identification of lipid metabolites on root surfaces.

  16. Imprint Desorption Electrospray Ionization Mass Spectrometry Imaging for Monitoring Secondary Metabolites Production during Antagonistic Interaction of Fungi.

    PubMed

    Tata, Alessandra; Perez, Consuelo; Campos, Michel L; Bayfield, Mark A; Eberlin, Marcos N; Ifa, Demian R

    2015-12-15

    Direct analysis of microbial cocultures grown on agar media by desorption electrospray ionization mass spectrometry (DESI-MS) is quite challenging. Due to the high gas pressure upon impact with the surface, the desorption mechanism does not allow direct imaging of soft or irregular surfaces. The divots in the agar, created by the high-pressure gas and spray, dramatically change the geometry of the system decreasing the intensity of the signal. In order to overcome this limitation, an imprinting step, in which the chemicals are initially transferred to flat hard surfaces, was coupled to DESI-MS and applied for the first time to fungal cocultures. Note that fungal cocultures are often disadvantageous in direct imaging mass spectrometry. Agar plates of fungi present a complex topography due to the simultaneous presence of dynamic mycelia and spores. One of the most devastating diseases of cocoa trees is caused by fungal phytopathogen Moniliophthora roreri. Strategies for pest management include the application of endophytic fungi, such as Trichoderma harzianum, that act as biocontrol agents by antagonizing M. roreri. However, the complex chemical communication underlying the basis for this phytopathogen-dependent biocontrol is still unknown. In this study, we investigated the metabolic exchange that takes place during the antagonistic interaction between M. roreri and T. harzianum. Using imprint-DESI-MS imaging we annotated the secondary metabolites released when T. harzianum and M. roreri were cultured in isolation and compared these to those produced after 3 weeks of coculture. We identified and localized four phytopathogen-dependent secondary metabolites, including T39 butenolide, harzianolide, and sorbicillinol. In order to verify the reliability of the imprint-DESI-MS imaging data and evaluate the capability of tape imprints to extract fungal metabolites while maintaining their localization, six representative plugs along the entire M. roreri/T. harzianum

  17. Laser mass spectrometry of biological molecular ions produced by matrix assisted laser desorption ionization (MALDI)

    NASA Astrophysics Data System (ADS)

    Jia, W. J.; Kosmidis, C.; Ledingham, K. W. D.; Scott, C. T. J.; Singhal, R. P.

    1996-10-01

    A tandem reflectron laser mass spectrometer is used for investigations of the photo fragmentation of molecular ions. The observed fragmentation patterns for 2,5-dihydrobenzoic acid and its fragments ions are analysed. PTH-trytophan and PTH-valine ions, generated by MALDI, are photodissociated and their fragmentation pattern is discussed.

  18. Evaluation and performance of desorption electrospray ionization using a triple quadrupole mass spectrometer for quantitation of pharmaceuticals in plasma.

    PubMed

    Kennedy, Joseph H; Wiseman, Justin M

    2010-02-01

    The present work describes the methodology and investigates the performance of desorption electrospray ionization (DESI) combined with a triple quadrupole mass spectrometer for the quantitation of small drug molecules in human plasma. Amoxepine, atenolol, carbamazepine, clozapine, prazosin, propranolol and verapamil were selected as target analytes while terfenadine was selected as the internal standard common to each of the analytes. Protein precipitation of human plasma using acetonitrile was utilized for all samples. Limits of detection were determined for all analytes in plasma and shown to be in the range 0.2-40 ng/mL. Quantitative analysis of amoxepine, prazosin and verapamil was performed over the range 20-7400 ng/mL and shown to be linear in all cases with R(2) >0.99. In most cases, the precision (relative standard deviation) and accuracy (relative error) of each method were less than or equal to 20%, respectively. The performance of the combined techniques made it possible to analyze each sample in 15 s illustrating DESI tandem mass spectrometry (MS/MS) as powerful tool for the quantitation of analytes in deproteinized human plasma. PMID:20049888

  19. Thin-layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemica lionization

    SciTech Connect

    Ovchinnikova, Olga S; Van Berkel, Gary J

    2010-01-01

    An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high-performance thin-layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read-out resolution, detection limits, and surface type are discussed.

  20. Inflation-Fixation Method for Lipidomic Mapping of Lung Biopsies by Matrix Assisted Laser Desorption/Ionization-Mass Spectrometry Imaging.

    PubMed

    Carter, Claire L; Jones, Jace W; Farese, Ann M; MacVittie, Thomas J; Kane, Maureen A

    2016-05-01

    Chronic respiratory diseases are among the leading causes of deaths worldwide and major contributors of morbidity and global disease burden. To appropriately investigate lung disease, the respiratory airways must be fixed in their physiological orientation and should be inflated prior to investigations. We present an inflation-fixation method that enables lipidomic investigations of whole lung samples and resected biopsy specimens by matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI). Formalin-inflation enables sample preparation to parallel standard clinical and surgical procedures, in addition to greatly reducing the complexity of analysis, by decreasing the number of analytes in the MALDI plume and reducing adduct formation in the resulting mass spectra. The reduced complexity increased sensitivity and enabled high-resolution imaging acquisitions without any loss in analyte detection at 10 and 20 μm scans. We present a detailed study of over 100 lipid ions detected in positive and negative ion modes covering the conducting and respiratory airways and parts of the peripheral nervous tissue running through the lungs. By defining the resolution required for clear definition of the alveolar space and thus the respiratory airways we have provided a guideline for MSI investigations of respiratory diseases involving the airways, including the interstitium. This study has provided a detailed map of lipid species and their localization within larger mammalian lung samples, for the first time, thus categorizing the lipidome for future MALDI-MSI studies of pulmonary diseases. PMID:27028398

  1. Matrix-assisted laser desorption using a fast-atom bombardment ion source and a magnetic mass spectrometer.

    PubMed

    Annan, R S; Köchling, H J; Hill, J A; Biemann, K

    1992-04-01

    A conventional fast-atom bombardment (FAB) ion source was used to achieve matrix-assisted laser desorption (MALD) in a high-mass, double-focusing, magnetic mass spectrometer. The pulsed ion signals generated by irradiation of a mixture of sample and matrix (2,5-dihydroxybenzoic acid) with either a XeF excimer laser (353 nm) or a nitrogen laser (337 nm) were recorded with a focal-plane detector. A resolution (full-width at half maximum) of 4500 was achieved at m/z 1347.7 (the peptide substance P), 2500 for CsI cluster ions at m/z 10,005.7, and 1250 for the isotope cluster of the small protein cytochrome c (horse) [M+H]+ = m/z 12,360 (average). Sensitivity is demonstrated with 11 fmol of substance P. A survey scan is taken to locate the m/z of the sample molecular ion. The segment that contains the sample can then be integrated for a longer time to produce a better signal-to-noise ratio. In addition to higher sensitivity and lower matrix interference, the advantage of MALD over FAB is the former's lower susceptibility to the presence of salts, and competition between hydrophobic and hydrophilic components of a mixture. This feature is demonstrated by the complete MALD spectrum of a crude partial tryptic digest of sperm-whale apomyoglobin, containing 24 peptides, representing the entire sequence of this protein. PMID:1373978

  2. Chemical Characterization of Crude Petroleum Using Nanospray Desorption Electrospray Ionization Coupled with High-Resolution Mass Spectrometry

    SciTech Connect

    Eckert, Peter A.; Roach, Patrick J.; Laskin, Alexander; Laskin, Julia

    2012-02-07

    Nanospray desorption electrospray ionization (nano-DESI) combined with high-resolution mass spectrometry was used for the first time for the analysis of liquid petroleum crude oil samples. The analysis was performed in both positive and negative ionization modes using three solvents one of which (acetonitrile/toluene mixture) is commonly used in petroleomics studies while two other polar solvents (acetonitrile/water and methanol/water mixtures) are generally not compatible with petroleum characterization using mass spectrometry. The results demonstrate that nano-DESI analysis efficiently ionizes petroleum constituents soluble in a particular solvent. When acetonitrile/toluene is used as a solvent, nano-DESI generates electrospray-like spectra. In contrast, strikingly different spectra were obtained using acetonitrile/water and methanol/water. Comparison with the literature data indicates that these solvents selectively extract water-soluble constituents of the crude oil. Water-soluble compounds are predominantly observed as sodium adducts in nano-DESI spectra indicating that addition of sodium to the solvent may be a viable approach for efficient ionization of water-soluble crude oil constituents. Nano-DESI enables rapid screening of different classes of compounds in crude oil samples using solvents that are rarely used for petroleum characterization.

  3. Evaluation of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Second-Generation Lignin Analysis

    PubMed Central

    Richel, Aurore; Vanderghem, Caroline; Simon, Mathilde; Wathelet, Bernard; Paquot, Michel

    2012-01-01

    Matrix-Assisted Laser Desorption/Ionization time-of-flight (MALDI-TOF) mass spectrometry is evaluated as an elucidation tool for structural features and molecular weights estimation of some extracted herbaceous lignins. Optimization of analysis conditions, using a typical organic matrix, namely α-cyano-4-hydroxycinnamic acid (CHCA), in combination with α-cyclodextrin, allows efficient ionization of poorly soluble lignin materials and suppression of matrix-related ions background. Analysis of low-mass fragments ions (m/z 100–600) in the positive ion mode offers a “fingerprint” of starting lignins that could be a fine strategy to qualitatively identify principal inter-unit linkages between phenylpropanoid units. The molecular weights of lignins are estimated using size exclusion chromatography and compared to MALDI-TOF-MS profiles. Miscanthus (Miscanthus x giganteus) and Switchgrass (Panicum Virgatum L.) lignins, recovered after a formic acid/acetic acid/water process or aqueous ammonia soaking, are selected as benchmarks for this study. PMID:23300342

  4. Coupling Laser Diode Thermal Desorption with Acoustic Sample Deposition to Improve Throughput of Mass Spectrometry-Based Screening.

    PubMed

    Haarhoff, Zuzana; Wagner, Andrew; Picard, Pierre; Drexler, Dieter M; Zvyaga, Tatyana; Shou, Wilson

    2016-02-01

    The move toward label-free screening in drug discovery has increased the demand for mass spectrometry (MS)-based analysis. Here we investigated the approach of coupling acoustic sample deposition (ASD) with laser diode thermal desorption (LDTD)-tandem mass spectrometry (MS/MS). We assessed its use in a cytochrome P450 (CYP) inhibition assay, where a decrease in metabolite formation signifies CYP inhibition. Metabolite levels for 3 CYP isoforms were measured as CYP3A4-1'-OH-midazolam, CYP2D6-dextrorphan, and CYP2C9-4'-OH-diclofenac. After incubation, samples (100 nL) were acoustically deposited onto a stainless steel 384-LazWell plate, then desorbed by an infrared laser directly from the plate surface into the gas phase, ionized by atmospheric pressure chemical ionization (APCI), and analyzed by MS/MS. Using this method, we achieved a sample analysis speed of 2.14 s/well, with bioanalytical performance comparable to the current online solid-phase extraction (SPE)-based MS method. An even faster readout speed was achieved when postreaction sample multiplexing was applied, where three reaction samples, one for each CYP, were transferred into the same well of the LazWell plate. In summary, LDTD coupled with acoustic sample deposition and multiplexing significantly decreased analysis time to 0.7 s/sample, making this MS-based approach feasible to support high-throughput screening (HTS) assays. PMID:26420787

  5. Distinct features of matrix-assisted 6 microm infrared laser desorption/ionization mass spectrometry in biomolecular analysis.

    PubMed

    Tajiri, Michiko; Takeuchi, Takae; Wada, Yoshinao

    2009-08-15

    Midinfrared-matrix-assisted laser desorption/ionization mass spectrometry (mid-IR-MALDI MS) with a laser emission in the 6 microm wavelength range, which utilizes energy absorption at the C=O double-bond stretch region, was applied to biomolecular analysis. The softness of IR-MALDI MS was evident in the negative ion mode yielding clean mass spectra of [M - H](-) ions for acidic biomolecules with sulfate, phosphate, or carboxylate groups, resulting in better sensitivity than ultraviolet (UV)-MALDI MS. There was no substantial loss of sialic acid due to the prompt fragmentation occurring in IR-MALDI of sialylated glycoconjugates such as gangliosides. Furthermore, the advantage of the low photon energy of IR is that, for the first time, intact protonated molecules of S-nitrosylated peptides can be detected by MALDI MS. In the analysis of redox-sensitive molecules including methylene blue and riboflavin, reductive hydrogenation was minimal, suggesting few hydrogen radicals to have formed in the plume, in contrast to UV-MALDI. In conjunction with a potent new matrix, oxamide, requiring smaller laser fluence, distinct features of the 6 microm IR wavelength range are anticipated to remove one of the limitations of MALDI MS for biomolecular analysis. PMID:19627133

  6. In Situ Analysis of Bacterial Lipopeptide Antibiotics by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

    PubMed

    Debois, Delphine; Ongena, Marc; Cawoy, Hélène; De Pauw, Edwin

    2016-01-01

    Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a technique developed in the late 1990s enabling the two-dimensional mapping of a broad variety of biomolecules present at the surface of a sample. In many applications including pharmaceutical studies or biomarker discovery, the distribution of proteins, lipids or drugs, and metabolites may be visualized within tissue sections. More recently, MALDI MSI has become increasingly applied in microbiology where the versatility of the technique is perfectly suited to monitor the metabolic dynamics of bacterial colonies. The work described here is focused on the application of MALDI MSI to map secondary metabolites produced by Bacilli, especially lipopeptides, produced by bacterial cells during their interaction with their environment (bacteria, fungi, plant roots, etc.). This chapter addresses the advantages and challenges that the implementation of MALDI MSI to microbiological samples entails, including detailed protocols on sample preparation (from both microbiologist and mass spectrometrist points of view), matrix deposition, and data acquisition and interpretation. Lipopeptide images recorded from confrontation plates are also presented. PMID:26831708

  7. Rapid assignment of malting barley varieties by matrix-assisted laser desorption-ionisation - Time-of-flight mass spectrometry.

    PubMed

    Šedo, Ondrej; Kořán, Michal; Jakešová, Michaela; Mikulíková, Renata; Boháč, Michal; Zdráhal, Zbyněk

    2016-09-01

    A method for discriminating malting barley varieties based on direct matrix-assisted laser desorption-ionisation - time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting of proteins was developed. Signals corresponding to hordeins were obtained by simple mixing of powdered barley grain with a MALDI matrix solution containing 12.5mgmL(-1) of ferulic acid in an acetonitrile:water:formic acid 50:33:17 v/v/v mixture. Compared to previous attempts at MALDI-TOF mass spectrometric analysis of barley proteins, the extraction and fractionation steps were practically omitted, resulting in a significant reduction in analytical time and costs. The discriminatory power was examined on twenty malting barley varieties and the practicability of the method was tested on sixty barley samples acquired from Pilsner Urquell Brewery. The method is proposed as a rapid tool for variety assignment and purity determination of malting barley that may replace gel electrophoresis currently used for this purpose. PMID:27041307

  8. Molecular characterization of organic aerosol using nanospray desorption/electrospray ionization mass spectrometry: CalNex 2010 field study

    NASA Astrophysics Data System (ADS)

    O'Brien, Rachel E.; Laskin, Alexander; Laskin, Julia; Liu, Shang; Weber, Robin; Russell, Lynn M.; Goldstein, Allen H.

    2013-04-01

    Aerosol samples from the CalNex 2010 field study were analyzed using high-resolution mass spectrometry (HR-MS) coupled to a nanospray desorption/electrospray ionization (nano-DESI) source. The samples were collected in Bakersfield, CA on June 22-23, 2010. The chemical formulas of over 850 unique molecular species were detected in the mass range of 50-400 m/z using positive mode ESI of aerosol samples in the 0.18-0.32 μm size range. Our analysis focused on identification of two main groups: compounds containing only carbon, hydrogen, and oxygen (CHO), and nitrogen-containing organic compounds (NOC). The NOC accounted for 40% (by number) of the compounds observed in the afternoon, and for 52% in the early morning samples. By comparing plausible reactant-product pairs, we propose that over 50% of the NOC in each sample could have been formed through reactions transforming carbonyls into imines. The CHO only compounds were dominant in the afternoon suggesting a photochemical source. The average O/C ratios of all observed compounds were fairly consistent throughout the day, ranging from 0.33 in the morning to 0.37 at night. We conclude that both photooxidation and ammonia chemistry may play a role in forming the compounds observed in this mixed urban-rural environment.

  9. Analysis of ancient Greco-Roman cosmetic materials using laser desorption ionization and electrospray ionization mass spectrometry.

    PubMed

    Van Elslande, Elsa; Guérineau, Vincent; Thirioux, Vincent; Richard, Ghislaine; Richardin, Pascale; Laprévote, Olivier; Hussler, Georges; Walter, Philippe

    2008-04-01

    Microsamples of pink cosmetic powders from the Greco-Roman period were analyzed using two complementary analytical approaches for identification of the colouring agents (lake pigments originally manufactured from madder plants with an inert binder, usually a metallic salt) present in the samples. The first technique was a methanolic acidic extraction of the archaeological samples with an additional ethyl acetate extraction of the anthraquinone-type colouring agents which were identified using high performance liquid chromatography coupled to electrospray ionization with high resolution mass spectrometry (LC-ESI-HRMS), and the second was direct analysis of a microsample by laser desorption ionization-mass spectrometry (LDI-MS). The latter technique is well suited when the quantity of samples is very low. This soft ionization technique enables the detection of very small quantities of compounds using the combination of positive and negative-ion modes. It was also successfully applied for the direct analysis of some laboratory-made reference compounds. However, the presence of lead in one of these ancient samples induced a spectral suppression phenomenon. In this case and conditional on a sufficient quantity of available sample, the former method is better adapted for the characterization of these anthraquinone-type molecules. This study also confirmed that purpurin, munjistin, and pseudopurpurin are the principal colouring agents present in these ancient cosmetic powders constituted from madder plants. PMID:18320177

  10. Molecular Characterization of Organic Aerosol Using Nanospray Desorption/Electrospray Ionization Mass Spectrometry: CalNex 2010 field study

    SciTech Connect

    O'Brien, Rachel E.; Laskin, Alexander; Laskin, Julia; Liu, Shang; Weber, Robin; Russell, Lynn; Goldstein, Allen H.

    2013-04-01

    Aerosol samples from the CalNex 2010 field study were analyzed using high resolution mass spectrometry (HR-MS) coupled to a nanospray-desorption/electrospray ionization (nano-DESI) source. The samples were collected in Bakersfield, CA on June 22-23, 2010. The chemical formulas of over 1300 unique molecular species were detected in the mass range of 50-800 m/z. Our analysis focused on identification of two main groups: compounds containing only carbon, hydrogen, and oxygen (CHO only), and nitrogen-containing organic compounds (NOC). The NOC accounted for 35% (by number) of the compounds observed in the afternoon, and for 59% in the early morning samples. By comparing plausible reactant-product pairs, we propose that over 50% of the NOC in each sample could have been formed through reactions transforming carbonyls into imines. The CHO only compounds were dominant in the afternoon suggesting a photochemical source. The average O:C ratios of all observed compounds were fairly consistent throughout the day, ranging from 0.34 in the early morning to 0.37 at night. We conclude that both photooxidation and ammonia chemistry play important roles in forming the compounds observed in this mixed urban-rural environment.

  11. Comprehensive assignment of mass spectral signatures from individual Bacillus atrophaeus spores in matrix-free laser desorption/ionization bioaerosol mass spectrometry.

    PubMed

    Srivastava, Abneesh; Pitesky, Maurice E; Steele, Paul T; Tobias, Herbert J; Fergenson, David P; Horn, Joanne M; Russell, Scott C; Czerwieniec, Gregg A; Lebrilla, Carlito B; Gard, Eric E; Frank, Matthias

    2005-05-15

    We have fully characterized the mass spectral signatures of individual Bacillus atrophaeus spores obtained using matrix-free laser desorption/ionization bioaerosol mass spectrometry (BAMS). Mass spectra of spores grown in unlabeled, 13C-labeled, and 15N-labeled growth media were used to determine the number of carbon and nitrogen atoms associated with each mass peak observed in mass spectra from positive and negative ions. To determine the parent ion structure associated with fragment ion peaks, the fragmentation patterns of several chemical standards were independently determined. Our results confirm prior assignments of dipicolinic acid, amino acids, and calcium complex ions made in the spore mass spectra. The identities of several previously unidentified mass peaks, key to the recognition of Bacillus spores by BAMS, have also been revealed. Specifically, a set of fragment peaks in the negative polarity is shown to be consistent with the fragmentation pattern of purine nucleobase-containing compounds. The identity of m/z = +74, a marker peak that helps discriminate B. atrophaeus from Bacillus thuringiensis spores grown in rich media is [N1C4H12]+. A probable precursor molecule for the [N1C4H12]+ ion observed in spore spectra is trimethylglycine (+N(CH3)3CH2COOH), which produces a m/z = +74 peak when ionized in the presence of dipicolinic acid. A clear assignment of all the mass peaks in the spectra from bacterial spores, as presented in this work, establishes their relationship to the spore chemical composition and facilitates the evaluation of the robustness of "marker" peaks. This is especially relevant for peaks that have been used to discriminate Bacillus spore species, B. thuringiensis and B. atrophaeus, in our previous studies. PMID:15889924

  12. Interlaboratory Comparison of Intact-Cell Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Results for Identification and Differentiation of Brucella spp.

    PubMed Central

    Karger, Axel; Melzer, Falk; Timke, Markus; Bettin, Barbara; Kostrzewa, Markus; Nöckler, Karsten; Hohmann, Angelika; Tomaso, Herbert; Neubauer, Heinrich

    2013-01-01

    Classical microbiological diagnosis of human brucellosis is time-consuming, hazardous, and subject to variable interpretation. Intact-cell matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the routine identification of Brucella spp. Analysis of mass peak patterns allowed accurate identification to the genus level. However, statistical models based on peak intensities were needed for definite species differentiation. Interlaboratory comparison confirmed the reproducibility of the results. PMID:23850950

  13. A mass spectrometric system for analyzing thermal desorption spectra of ion-implanted argon and cesium in tungsten. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Wood, G. M., Jr.

    1974-01-01

    A mass spectrometric system for determining the characteristics of materials used in instrumental development and aerospace applications was developed. The desorption spectra of cesium that was ion-implanted into polycrystalline tungsten and the effects on the spectra of bombardment of the tungsten by low energy (70 eV) electrons were investigated. Work function changes were measured by the retarding potential diode method. Flash desorption characteristics were observed and gas-reaction mechanisms of the surface of heated metal filaments were studied. Desorption spectra were measured by linearly increasing the sample temperature at a selected rate, the temperature cycling being generated from a ramp-driven dc power supply, with the mass spectrometer tuned to a mass number of interest. Results of the study indicate an anomolous desorption mechanism following an electron bombardment of the sample surface. The enhanced spectra are a function of the post-bombardment time and energy and are suggestive of an increased concentration of cesium atoms, up to 10 or more angstroms below the surface.

  14. Fuzzy Logic Classification of Imaging Laser Desorption Fourier Transform Mass Spectrometry Data

    SciTech Connect

    Timothy R. McJunkin; Jill R. Scott

    2008-06-01

    The fuzzy logic method is applied to classification of mass spectra obtained with an imaging internal source Fourier transform mass spectrometer (I2LD-FTMS). Traditionally, an operator uses the relative abundance of ions with specific mass-to-charge (m/z) ratios to categorize spectra. An operator does this by comparing the spectrum of m/z versus abundance of an unknown sample against a library of spectra from known samples. Automated positioning and acquisition allow the I2LD-FTMS to acquire data from very large grids, which would require classification of up to 3600 spectra per hour to keep pace with the acquisition. The tedious job of classifying numerous spectra generated in an I2LD-FTMS imaging application can be replaced by a fuzzy rule base if the cues an operator uses can be encapsulated. Appropriate methods for assigning fuzzy membership values for inputs (e.g., mass spectrum abundances) and choice of fuzzy inference operators to translate linguistic antecedent into confidence values for the consequence (or in this case the classification) is followed by using the maximum confidence and a necessary minimum threshold for making a crisp decision. This paper also describes a method for gathering statistics on ions, which are not currently used in the rule base, but which may be candidates for making the rule base more accurate and complete or to form new rule bases based on data obtained from known samples. A spatial method for classifying spectra with low membership values, based on neighboring sample classifications, is also presented.

  15. Development of a screening method for the analysis of organic pollutants in water using dual stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Tölgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltán

    2011-12-15

    The development of a method for screening of organic compounds with a wide range of physico-chemical properties in water, based on dual stir bar sorptive extraction coupled with thermal desorption and gas chromatography-mass spectrometry (dual SBSE-TD-GC-MS) is described. The investigated water sample is divided into two aliquots and extracted with stir bar sorptive extraction at two different conditions: using addition of methanol or sodium chloride, respectively. Following extraction, the two stir bars are inserted into the same glass thermal desorption liner and are simultaneously desorbed and analysed by GC-MS. The method optimisation was performed using 45 environmentally harmful substances with different volatilities (boiling point from 193 to 495°C), polarity (logK(ow) from 2.17 to 8.54) and acido-basic properties. The majority of model compounds was selected from the EU list of priority substances in the field of water policy and from the US EPA method 625, respectively. Optimisation was performed for extraction parameters (sample volume, extraction time, stirring rate, addition of modifiers) as well as for the thermal desorption conditions (desorption flow, desorption time, cryofocusing temperature). Performance characteristics (recovery, repeatability, carryover, linearity, limits of detection and quantification) were determined for the optimised method. An example of analysis of a contaminated groundwater sample is presented. PMID:22099662

  16. Thermal desorption single particle mass spectrometry of ambient aerosol in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhai, Jinghao; Wang, Xinning; Li, Jingyan; Xu, Tingting; Chen, Hong; Yang, Xin; Chen, Jianmin

    2015-12-01

    Submicron aerosol volatility, chemical composition, and mixing state were simultaneously measured using a thermodenuder (TD) in-line with a single particle aerosol mass spectrometry (SPAMS) during Nov.12 to Dec. 11 of 2014 in Shanghai. By heating up to 250 °C, the signals of refractory species such as elemental carbon, metallic compounds, and mineral dust in aerosols were enhanced in the mass spectra. At 250 °C, the main particle types present in the size range of 0.2-1.0 μm were biomass burning (37% by number) and elemental carbon (20%). From 1.0 to 2.0 μm, biomass burning (30%), dust (19%) and metal-rich (18%) were the primary particle types. CN- signal remained in the mass spectra of the heated biomass burning particles suggests the existence of some extremely low-volatility nitrogen-containing organics. Laboratory experiments were conducted by burning rice straws, the main source material of biomass burning particles in Southern China, to confirm the less volatile composition contributed by biomass burning. Strong CN- with relative area >0.21 was observed in most of the laboratory-made biomass burning particles when heated above 200 °C and was selected as a new marker to identify the biomass burning particles in the field. The TD-SPAMS measured the size-resolved chemical composition of the individual particle residues at different temperatures and offered more information on the aging processes of primary particles and their sources.

  17. Study of kinetic desorption rate constant in fish muscle and agarose gel model using solid phase microextraction coupled with liquid chromatography with tandem mass spectrometry.

    PubMed

    Togunde, Oluranti Paul; Oakes, Ken; Servos, Mark; Pawliszyn, Janusz

    2012-09-12

    This study aims to use solid phase microextraction (SPME), a simple tool to investigate diffusion rate (time) constant of selected pharmaceuticals in gel and fish muscle by comparing desorption rate of diffusion of the drugs in both agarose gel prepared with phosphate-buffered saline (PBS; pH 7.4) and fish muscle. The gel concentration (agarose gel model) that could be used to simulate tissue matrix (fish muscle) for free diffusion of drugs under in vitro and in vivo conditions was determined to model mass transfer phenomena between fibre polymer coating and environmental matrix such that partition coefficients and desorption time constant (diffusion coefficient) can be determined. SPME procedure involves preloading the extraction phase (fibre) with the standards from spiked PBS for 1h via direct extraction. Subsequently, the preloaded fibre is introduced to the sample such fish or agarose gel for specified time ranging from 0.5 to 60 h. Then, fibre is removed at specified time and desorbed in 100 μL of desorption solution (acetonitrile: water 1:1) for 90 min under agitation speed of 1000 rpm. The samples extract were immediately injected to the instrument and analysed using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS). The limit of detection of the method in gel and fish muscle was 0.01-0.07 ng mL(-1) and 0.07-0.34 ng g(-1), respectively, while the limit quantification was 0.10-0.20 ng mL(-1) in gel samples and 0.40-0.97 ng g(-1) in fish sample. The reproducibility of the method was good (5-15% RSD). The results suggest that kinetics of desorption of the compounds in fish tissue and different viscosity of gel can be determined using desorption time constant. In this study, desorption time constant which is directly related to desorption rate (diffusion kinetics) of selected drugs from the fibre to the gel matrix is faster as the viscosity of the gel matrix reduces from 2% (w/v) to 0.8% (w/v). As the concentration of gel reduces

  18. Determination of pharmaceutical compounds in skin by imaging matrix-assisted laser desorption/ionisation mass spectrometry.

    PubMed

    Bunch, Josephine; Clench, Malcolm R; Richards, Don S

    2004-01-01

    Matrix-assisted laser desorption/ionisation (MALDI) quadrupole time-of-flight mass spectrometry (Q-TOFMS) has been used to detect and image the distribution of a xenobiotic substance in skin. Porcine epidermal tissue was treated with 'Nizoral', a medicated shampoo containing ketoconazole (+/-)-1-acetyl-4-[p-[[(2R,4S)-2-(2,4-dichlorophenyl)-2-(imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) as active ingredient. Following incubation for 1 h at 37 degrees C all excess formulation was washed from the surface. A cross-section of the drug-treated tissue was then blotted onto a cellulose membrane, precoated in matrix (alpha-cyano-4-hydroxycinnamic acid (CHCA)), by airspray deposition. In separate experiments the tissue surface was treated with Nizoral within a triangular former, and subsequently blotted onto a matrix-coated membrane. Sample membranes were then mounted into the recess of specialised MALDI targets with adhesive tape. All samples were analysed by MALDI-TOFMS using an Applied Biosystem 'Q-star Pulsar i' hybrid Q-TOF mass spectrometer fitted with an orthagonal MALDI ion source and imaging software. Detection of the protonated molecule was readily achievable by this technique. Treatment of the tissue within a template gave rise to images depicting the expected distribution of the drug, demonstrating that this technique is capable of producing spatially useful data. Ion images demonstrating the permeation of the applied compound into the skin were achieved by imaging a cross-sectional imprint of treated tissue. A calibration graph for the determination of ketoconazole was prepared using the sodium adduct of the matrix ion as an internal standard. This enabled construction of a quantitative profile of drug in skin. Conventional haematoxylin and eosin staining and microscopy methods were employed to obtain a histological image of the porcine epidermal tissue. Superimposing the mass spectrometric and histological images appeared to indicate drug

  19. Identification of dermatophytes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    de Respinis, Sophie; Tonolla, Mauro; Pranghofer, Sigrid; Petrini, Liliane; Petrini, Orlando; Bosshard, Philipp P

    2013-07-01

    In this study we evaluated the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of dermatophytes in diagnostic laboratories. First, a spectral database was built with 108 reference strains belonging to 18 species of the anamorphic genera Epidermophyton, Microsporum and Trichophyton. All strains were well characterized by morphological criteria and ITS sequencing (gold standard). The dendrogram resulting from MALDI-TOF mass spectra was almost identical with the phylogenetic tree based on ITS sequencing. Subsequently, MALDI-TOF MS SuperSpectra were created for the identification of Epidermophyton floccosum, Microsporium audouinii, M. canis, M. gypseum (teleomorph: Arthroderma gypseum), M. gypseum (teleomorph: A. incurvatum), M. persicolor, A. benhamiae (Tax. Entity 3 and Am-Eur. race), T. erinacei, T. interdigitale (anthropophilic and zoophilic populations), T. rubrum/T. violaceum, T. tonsurans and T. terrestre. Because T. rubrum and T. violaceum did not present enough mismatches, a SuperSpectrum covering both species was created, and differentiation between them was done by comparison of eight specific peptide masses. In the second part of this study, MALDI-TOF MS with the newly created SuperSpectra was tested using 141 clinical isolates representing nine species. Analyses were done with 3-day-old cultures. Results were compared to morphological identification and ITS sequencing; 135/141 (95.8%) strains were correctly identified by MALDI-TOF MS compared to 128/141 (90.8%) by morphology. Therefore, MALDI-TOF MS has proven to be a useful and rapid identification method for dermatophytes. PMID:23228046

  20. The quantitative surface analysis of an antioxidant additive in a lubricant oil matrix by desorption electrospray ionization mass spectrometry

    PubMed Central

    Da Costa, Caitlyn; Reynolds, James C; Whitmarsh, Samuel; Lynch, Tom; Creaser, Colin S

    2013-01-01

    RATIONALE Chemical additives are incorporated into commercial lubricant oils to modify the physical and chemical properties of the lubricant. The quantitative analysis of additives in oil-based lubricants deposited on a surface without extraction of the sample from the surface presents a challenge. The potential of desorption electrospray ionization mass spectrometry (DESI-MS) for the quantitative surface analysis of an oil additive in a complex oil lubricant matrix without sample extraction has been evaluated. METHODS The quantitative surface analysis of the antioxidant additive octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix was carried out by DESI-MS in the presence of 2-(pentyloxy)ethyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as an internal standard. A quadrupole/time-of-flight mass spectrometer fitted with an in-house modified ion source enabling non-proximal DESI-MS was used for the analyses. RESULTS An eight-point calibration curve ranging from 1 to 80 µg/spot of octyl (4-hydroxy-3,5-di-tert-butylphenyl)propionate in an oil lubricant matrix and in the presence of the internal standard was used to determine the quantitative response of the DESI-MS method. The sensitivity and repeatability of the technique were assessed by conducting replicate analyses at each concentration. The limit of detection was determined to be 11 ng/mm2 additive on spot with relative standard deviations in the range 3–14%. CONCLUSIONS The application of DESI-MS to the direct, quantitative surface analysis of a commercial lubricant additive in a native oil lubricant matrix is demonstrated. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons, Ltd. PMID:24097398

  1. Imaging of Phospholipids in Formalin Fixed Rat Brain Sections by Matrix Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Carter, Claire L.; McLeod, Cameron W.; Bunch, Josephine

    2011-11-01

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a valuable tool for the analysis of molecules directly from tissue. Imaging of phospholipids is gaining widespread interest, particularly as these lipids have been implicated in a variety of pathologic processes. Formalin fixation (FF) is the standard protocol used in histology laboratories worldwide to preserve tissue for analysis, in order to aid in the diagnosis and prognosis of diseases. This study assesses MALDI imaging of phospholipids directly in formalin fixed tissue, with a view to future analysis of archival tissue. This investigation proves the viability of MALDI-MSI for studying the distribution of lipids directly in formalin fixed tissue, without any pretreatment protocols. High quality molecular images for several phosphatidylcholine (PC) and sphingomyelin (SM) species are presented. Images correspond well with previously published data for the analysis of lipids directly from freshly prepared tissue. Different ionization pathways are observed when analyzing fixed tissue compared with fresh, and this change was found to be associated with formalin buffers employed in fixation protocols. The ability to analyze lipids directly from formalin fixed tissue opens up new doors in the investigation of disease profiles. Pathologic specimens taken for histologic investigation can be analyzed by MALDI-MS to provide greater information on the involvement of lipids in diseased tissue.

  2. Rapid screening of mixed edible oils and gutter oils by matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Ng, Tsz-Tsun; So, Pui-Kin; Zheng, Bo; Yao, Zhong-Ping

    2015-07-16

    Authentication of edible oils is a long-term issue in food safety, and becomes particularly important with the emergence and wide spread of gutter oils in recent years. Due to the very high analytical demand and diversity of gutter oils, a high throughput analytical method and a versatile strategy for authentication of mixed edible oils and gutter oils are highly desirable. In this study, an improved matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) method has been developed for direct analysis of edible oils. This method involved on-target sample loading, automatic data acquisition and simple data processing. MALDI-MS spectra with high quality and high reproducibility have been obtained using this method, and a preliminary spectral database of edible oils has been set up. The authenticity of an edible oil sample can be determined by comparing its MALDI-MS spectrum and principal component analysis (PCA) results with those of its labeled oil in the database. This method is simple and the whole process only takes several minutes for analysis of one oil sample. We demonstrated that the method was sensitive to change in oil compositions and can be used for measuring compositions of mixed oils. The capability of the method for determining mislabeling enables it for rapid screening of gutter oils since fraudulent mislabeling is a common feature of gutter oils. PMID:26073811

  3. Determining estrogens using surface-assisted laser desorption/ionization mass spectrometry with silver nanoparticles as the matrix.

    PubMed

    Chiu, Tai-Chia; Chang, Lin-Chau; Chiang, Cheng-Kang; Chang, Huan-Tsung

    2008-09-01

    We describe the application of silver nanoparticles (Ag NPs) as matrices for the determination of three estrogens using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Because Ag NPs have extremely high absorption coefficients (1.2 x 10(8) M(-1) cm(-1)) at 337 nm, they are effective SALDI matrices when using a nitrogen laser. Three tested estrogens--estrone (E1), estradiol (E2), and estriol (E3)--adsorb weakly onto the surfaces of the Ag NPs, through van der Waals forces. After centrifugation, the concentrated analytes adsorbed on the Ag NPs were subjected directly to SALDI-MS analyses, with the limits of detection for E1, E2, and E3 being 2.23, 0.23, and 2.11 microM, respectively. The shot-to-shot and batch-to-batch variations for the three analytes were less than 9% and 13%, respectively. We validated the practicality of this present approach through the quantitation of E2 in human urine. Using this approach, we determined the concentration of E2 in a sample of a pregnant woman's urine to be 0.16+/-0.05 microM (n=10). PMID:18640850

  4. Steroid hormones analysis with surface-assisted laser desorption/ionization mass spectrometry using catechin-modified titanium dioxide nanoparticles.

    PubMed

    Chiu, Tai-Chia

    2011-10-30

    This paper describes the application of catechin-modified titanium dioxide nanoparticles (TiO(2) NPs) as matrices to analyze four steroid hormones by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The catechin-modified TiO(2) NPs have high absorbance at 337 nm and are effective SALDI matrices when using a nitrogen laser. Four test steroid hormones-cortisone, hydrocortisone, progesterone, and testosterone-were directly analyzed by SALDI-MS. The limits of detection at a signal-to-noise ratio of 3 for cortisone, hydrocortisone, progesterone, and testosterone were 1.62, 0.70, 0.66, and 0.23 μM, respectively. This approach provides good quantitative linearity for the four analytes (R(2)>0.986) with good reproducibility (the shot-to-shot and batch-to-batch variations for the four analytes were less than 10% and 15%, respectively). We validated the practicality of this approach-considering its advantages in sensitivity, repeatability, rapidity, and simplicity-through the analysis of testosterone in a urine sample. PMID:22063559

  5. Simultaneous imaging of multiple neurotransmitters and neuroactive substances in the brain by desorption electrospray ionization mass spectrometry.

    PubMed

    Shariatgorji, Mohammadreza; Strittmatter, Nicole; Nilsson, Anna; Källback, Patrik; Alvarsson, Alexandra; Zhang, Xiaoqun; Vallianatou, Theodosia; Svenningsson, Per; Goodwin, Richard J A; Andren, Per E

    2016-08-01

    With neurological processes involving multiple neurotransmitters and neuromodulators, it is important to have the ability to directly map and quantify multiple signaling molecules simultaneously in a single analysis. By utilizing a molecular-specific approach, namely desorption electrospray ionization mass spectrometry imaging (DESI-MSI), we demonstrated that the technique can be used to image multiple neurotransmitters and their metabolites (dopamine, dihydroxyphenylacetic acid, 3-methoxytyramine, serotonin, glutamate, glutamine, aspartate, γ-aminobutyric acid, adenosine) as well as neuroactive drugs (amphetamine, sibutramine, fluvoxamine) and drug metabolites in situ directly in brain tissue sections. The use of both positive and negative ionization modes increased the number of identified molecular targets. Chemical derivatization by charge-tagging the primary amines of molecules significantly increased the sensitivity, enabling the detection of low abundant neurotransmitters and other neuroactive substances previously undetectable by MSI. The sensitivity of the imaging approach of neurochemicals has a great potential in many diverse applications in fields such as neuroscience, pharmacology, drug discovery, neurochemistry, and medicine. PMID:27155126

  6. A metabolomic protocol for plant systematics by matrix-assisted laser-desorption/ionization time-of flight mass spectrometry.

    PubMed

    Ernst, Madeleine; Silva, Denise B; Silva, Ricardo; Monge, Marcelo; Semir, João; Vêncio, Ricardo Z N; Lopes, Norberto P

    2015-02-15

    Matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF MS) has been widely used for the identification and classification of microorganisms based on their proteomic fingerprints. However, the use of MALDI-TOF MS in plant research has been very limited. In the present study, a first protocol is proposed for metabolic fingerprinting by MALDI-TOF MS using three different MALDI matrices with subsequent multivariate data analysis by in-house algorithms implemented in the R environment for the taxonomic classification of plants from different genera, families and orders. By merging the data acquired with different matrices, different ionization modes and using careful algorithms and parameter selection, we demonstrate that a close taxonomic classification can be achieved based on plant metabolic fingerprints, with 92% similarity to the taxonomic classifications found in literature. The present work therefore highlights the great potential of applying MALDI-TOF MS for the taxonomic classification of plants and, furthermore, provides a preliminary foundation for future research. PMID:25622605

  7. Spatially resolved analysis of small molecules by matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI).

    PubMed

    Peukert, Manuela; Matros, Andrea; Lattanzio, Giuseppe; Kaspar, Stephanie; Abadía, Javier; Mock, Hans-Peter

    2012-02-01

    • Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) of tissues provides the means to analyse the spatial distributions of small molecules and proteins within tissues. This imaging technique is commonplace in medicinal and pharmaceutical research, but its application in plant science is very recent. Broader introduction requires specific adaptations for plant tissues. Sample preparation is of paramount importance in order to obtain high-quality spectra providing sufficient spatial resolution for compounds. Optimization is required for sectioning, choice of matrix and means of matrix deposition. • Here, we present our current protocols for the detection of small molecules in cryodissected immature barley (Hordeum vulgare) grains and tobacco (Nicotiana tabacum) roots. • Examples of MALDI-MSI measurements are provided, and the level of reproducibility across biological replicates is addressed. Furthermore, our approaches for the validation of distribution patterns and for the identification of molecules are described. • Finally, we discuss how MALDI-MSI can contribute to applied plant research. PMID:22126099

  8. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applied to virus identification.

    PubMed

    Calderaro, Adriana; Arcangeletti, Maria-Cristina; Rodighiero, Isabella; Buttrini, Mirko; Gorrini, Chiara; Motta, Federica; Germini, Diego; Medici, Maria-Cristina; Chezzi, Carlo; De Conto, Flora

    2014-01-01

    Virus detection and/or identification traditionally rely on methods based on cell culture, electron microscopy and antigen or nucleic acid detection. These techniques are good, but often expensive and/or time-consuming; furthermore, they not always lead to virus identification at the species and/or type level. In this study, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was tested as an innovative tool to identify human polioviruses and to identify specific viral protein biomarkers in infected cells. The results revealed MALDI-TOF MS to be an effective and inexpensive tool for the identification of the three poliovirus serotypes. The method was firstly applied to Sabin reference strains, and then to isolates from different clinical samples, highlighting its value as a time-saving, sensitive and specific technique when compared to the gold standard neutralization assay and casting new light on its possible application to virus detection and/or identification. PMID:25354905

  9. Determination of agrochemical compounds in soya plants by imaging matrix-assisted laser desorption/ionisation mass spectrometry.

    PubMed

    Mullen, Alexander K; Clench, Malcolm R; Crosland, Susan; Sharples, Kate R

    2005-01-01

    Detection and imaging of the herbicide mesotrione (2-(4-mesyl-2-nitrobenzoyl)cyclohexane-1,3-dione) and the fungicide azoxystrobin (methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate), on the surface of the soya leaf, and the detection and imaging of azoxystrobin inside the stem of the soya plant, have been achieved using matrix-assisted laser desorption/ionisation quadrupole time-of-flight mass spectrometry. In leaf analysis experiments, the two pesticides were deposited onto the surface of individual soya leaves on growing plants. The soya leaves were removed and prepared for direct and indirect (following blotting onto matrix-coated cellulose membranes) imaging analysis at different periods after initial pesticide application. In stem analysis experiments, azoxystrobin was added to the nutrient solution of a soya plant growing in a hydroponics system. The plant was left for 48 h, and then horizontal and vertical stem sections were prepared for direct imaging analysis. The images obtained demonstrate the applicability of MALDI imaging to the detection and imaging of small organic compounds in plant tissue and further extend the analytical repertoire of the versatile MALDI technique. PMID:16106343

  10. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry.

    PubMed

    Ellis, Wade C; Lewis, Charlotte R; Openshaw, Anna P; Farnsworth, Paul B

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration. Graphical Abstract ᅟ. PMID:27380389

  11. Quantitative mass spectrometry imaging of small-molecule neurotransmitters in rat brain tissue sections using nanospray desorption electrospray ionization.

    PubMed

    Bergman, Hilde-Marléne; Lundin, Erik; Andersson, Malin; Lanekoff, Ingela

    2016-06-01

    Small molecule neurotransmitters are essential for the function of the nervous system, and neurotransmitter imbalances are often connected to neurological disorders. The ability to quantify such imbalances is important to provide insights into the biochemical mechanisms underlying the disorder. This proof-of-principle study presents online quantification of small molecule neurotransmitters, specifically acetylcholine, γ-aminobutyric acid (GABA) and glutamate, in rat brain tissue sections using nanospray desorption electrospray ionization (nano-DESI) mass spectrometry imaging. By incorporating deuterated internal standards in the nano-DESI solvent we show identification, accurate mapping, and quantification of these small neurotransmitters in rat brain tissue without introducing any additional sample preparation steps. We find that GABA is about twice as abundant in the medial septum-diagonal band complex (MSDB) as in the cortex, while glutamate is about twice as abundant in the cortex as compared to the MSDB. The study shows that nano-DESI is well suited for imaging of small molecule neurotransmitters in health and disease. PMID:26859000

  12. Direct detection of illicit drugs from biological fluids by desorption/ionization mass spectrometry with nanoporous silicon microparticles.

    PubMed

    Guinan, T M; Kirkbride, P; Della Vedova, C B; Kershaw, S G; Kobus, H; Voelcker, N H

    2015-12-01

    Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high throughput analytical technique capable of detecting low molecular weight analytes, including illicit drugs, and with potential applications in forensic toxicology as well as athlete and workplace testing, particularly for biological fluids (oral fluids, urine and blood). However, successful detection of illicit drugs using SALDI-MS often requires extraction steps to reduce the inherent complexity of biological fluids. Here, we demonstrate an all-in-one extraction and analytical system consisting of hydrophobically functionalized porous silicon microparticles (pSi-MPs) for affinity SALDI-MS of prescription and illicit drugs. This novel approach allows for the analysis of drugs from multiple biological fluids without sample preparation protocols. The effect of pSi-MP size, pore diameter, pore depth and functionalization on analytical performance is investigated. pSi-MPs were optimized for the rapid and high sensitivity detection of methadone, cocaine and 3,4-methylenedioxymethamphetamine (MDMA). This optimized system allowed extraction and detection of methadone from spiked saliva and clinical urine samples. Furthermore, by detecting oxycodone in additional clinical saliva and plasma samples, we were able to demonstrate the versatility of the pSi-MP SALDI-MS technique. PMID:26502296

  13. Automation and Control of an Imaging Internal Laser Desorption Fourier Transform Mass Spectrometer (I2LD-FTMS)

    SciTech Connect

    McJunkin, Timothy R; Tranter, Troy Joseph; Scott, Jill Rennee

    2002-06-01

    This paper describes the automation of an imaging internal source laser desorption Fourier transform mass spectrometer (I2LD-FTMS). The I2LD-FTMS consists of a laser-scanning device [Scott and Tremblay, Rev. Sci. Instrum. 2002, 73, 1108–1116] that has been integrated with a laboratory-built FTMS using a commercial data acquisition system (ThermoFinnigan FT/MS, Bremen, Germany). A new user interface has been developed in National Instrument's (Austin, Texas) graphical programming language LabVIEW to control the motors of the laser positioning system and the commercial FTMS data acquisition system. A feature of the FTMS software that allows the user to write macros in a scripting language is used creatively to our advantage in creating a mechanism to control the FTMS from outside its graphical user interface. The new user interface also allows the user to configure target locations. Automation of the data analysis along with data display using commercial graphing software is also described.

  14. Liquid-phase microextraction and desorption electrospray ionization mass spectrometry for identification and quantification of basic drugs in human urine.

    PubMed

    Thunig, Janina; Flø, Linda; Pedersen-Bjergaard, Stig; Hansen, Steen Honoré; Janfelt, Christian

    2012-01-30

    Hollow fibre liquid-phase microextraction (LPME) and desorption electrospray ionization mass spectrometry (DESI-MS) were evaluated for the identification and quantification of basic drugs in human urine samples. The selective extraction capabilities of three-phase LPME provided a significant reduction in the matrix effects otherwise observed in direct DESI-MS analysis of urine samples. Aqueous LPME extracts (in 10 mM HCl) were deposited on porous Teflon, dried at room temperature, and the dried spots were then analyzed directly with DESI-MS in full scan mode. Pethidine, diphenhydramine, nortriptyline, and methadone were used as model compounds for identification, and their limits of identification were determined to be 100, 25, 100, and 30 ng/mL, respectively. In a reliability test with 19 spiked urine samples, 100% of the positive samples containing the model drugs in concentrations at or above the limit of identification were identified. Diphenhydramine was used as a model compound for quantitative analysis with diphenhydramine-d(5) as an internal standard. The calibration curve was linear in the range 50-2000 ng/mL (R(2) = 0.992) with a limit of quantification at approximately 140 ng/mL. The intra- and inter-day relative standard deviations were <9.5%. In a reliability test with six spiked urine samples, deviations between the measured and the true values for diphenhydramine were in the range 0.2-22.9%. PMID:22173801

  15. Effects of Tailored Surface Chemistry on Desorption Electrospray Ionization Mass Spectrometry: a Surface-Analytical Study by XPS and AFM

    NASA Astrophysics Data System (ADS)

    Penna, Andrea; Careri, Maria; Spencer, Nicholas D.; Rossi, Antonella

    2015-08-01

    Since it was proposed for the first time, desorption electrospray ionization-mass spectrometry (DESI-MS) has been evaluated for applicability in numerous areas. Elucidations of the ionization mechanisms and the subsequent formation of isolated gas-phase ions have been proposed so far. In this context, the role of both surface and pneumatic effects on ion-formation yield has recently been investigated. Nevertheless, the effect of the surface chemistry has not yet been completely understood. Functionalized glass surfaces have been prepared, in order to tailor surface performance for ion formation. Three substrates were functionalized by depositing three different silanes [3-mercaptopropyltriethoxysilane (MTES), octyltriethoxysilane (OTES), and 1H,1H,2H,2H-perfluorooctyltriethoxy-silane (FOTES)] from toluene solution onto standard glass slides. Surface characterization was carried out by contact-angle measurements, tapping-mode atomic force microscopy, and X-ray photoelectron spectroscopy. Morphologically homogeneous and thickness-controlled films in the nm range were obtained, with surface free energies lying between 15 and 70 mJ/m2. These results are discussed, together with those of DESI-MS on low-molecular-weight compounds such as melamine, tetracycline, and lincomycin, also taking into account the effects of the sprayer potential and its correlation with surface wettability. The results demonstrate that ion-formation efficiency is affected by surface wettability, and this was demonstrated operating above and below the onset of the electrospray.

  16. Improved Cell Typing by Charge-State Deconvolution of matrix-assisted laser desorption/ionization Mass Spectra

    SciTech Connect

    Wilkes, Jon G.; Buzantu, Dan A.; Dare, Diane J.; Dragan, Yvonne P.; Chiarelli, M. Paul; Holland, Ricky D.; Beaudoin, Michael; Heinze, Thomas M.; Nayak, Rajesh; Shvartsburg, Alexandre A.

    2006-05-30

    Robust, specific, and rapid identification of toxic strains of bacteria and viruses, to guide the mitigation of their adverse health effects and optimum implementation of other response actions, remains a major analytical challenge. This need has driven the development of methods for classification of microorganisms using mass spectrometry, particularly matrix-assisted laser desorption ionization MS (MALDI) that allows high throughput analyses with minimum sample preparation. We describe a novel approach to cell typing based on pattern recognition of MALDI spectra, which involves charge-state deconvolution in conjunction with a new correlation analysis procedure. The method is applicable to both prokaryotic and eukaryotic cells. Charge-state deconvolution improves the quantitative reproducibility of spectra because multiply-charged ions resulting from the same biomarker attaching a different number of protons are recognized and their abundances are combined. This allows a clearer distinction of bacterial strains or of cancerous and normal liver cells. Improved class distinction provided by charge-state deconvolution was demonstrated by cluster spacing on canonical variate score charts and by correlation analyses. Deconvolution may enhance detection of early disease state or therapy progress markers in various tissues analyzed by MALDI.

  17. Distinguishing chinese star anise from Japanese star anise using thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Howes, Melanie-Jayne R; Kite, Geoffrey C; Simmonds, Monique S J

    2009-07-01

    The volatile compounds from the pericarps of Illicium anisatum L., Illicium brevistylum A.C.Sm., Illicium griffithii Hook.f. & Thomson, Illicium henryi Diels, Illicium lanceolatum A.C.Sm., Illicium majus Hook.f. & Thomson, Illicium micranthum Dunn, and Illicium verum Hook.f. were examined by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The volatiles desorbed from the pericarps of I. verum (Chinese star anise), the species traded for culinary purposes, were generally characterized by a high proportion of (E)-anethole (57.6-77.1%) and the presence of foeniculin; the latter was otherwise only detected in the pericarps of I. lanceolatum. In the pericarps of all other species analyzed, the percentage composition of (E)-anethole was comparatively lower (

  18. Analysis of free fatty acids by ultraviolet laser desorption ionization mass spectrometry using insect wings as hydrophobic sample substrates.

    PubMed

    Pirkl, Alexander; Meier, Martin; Popkova, Yulia; Letzel, Matthias; Schnapp, Andreas; Schiller, Jürgen; Dreisewerd, Klaus

    2014-11-01

    Physiologically relevant free fatty acids (FFAs) were analyzed by UV-laser desorption/ionization orthogonal extracting time-of-flight mass spectrometry (LDI-oTOF-MS). Dissected wings from Drosophila melanogaster fruit flies were used as the hydrophobic, laser energy strongly absorbing sample substrates. Using untreated substrates produces predominantly molecular [M + K](+) ions of the FFAs, whereas other alkali metal adducts can be generated by treating the wings with the corresponding alkali hydroxide before spotting of analyte. Limits of detection for the positive ion mode were determined for mixtures of isolated FFAs to values in the low 10 pmol range. Specific values depend on chain length and degree of unsaturation. R(2) coefficients for the analysis of saturated FFAs were found to be generally close to 0.98 over about 3 orders of magnitude if an internal standard (15:0 FFA) was added. Semiquantitative analyses of mixtures containing unsaturated FFAs are also possible but require more effort on the calibration strategy. Notably, both saturated and (poly-)unsaturated FFAs are detected sensitively in the presence of relatively high concentrations of other physiologically abundant lipids (phospholipids and triacyclglycerols). This simplifies screening of the FFA composition in crude tissue extracts. This feature is demonstrated by the analysis of a crude liver extract and that of fingermarks. PMID:25268473

  19. Screening of the binding of small molecules to proteins by desorption electrospray ionization mass spectrometry combined with protein microarray.

    PubMed

    Yao, Chenxi; Wang, Tao; Zhang, Buqing; He, Dacheng; Na, Na; Ouyang, Jin

    2015-11-01

    The interaction between bioactive small molecule ligands and proteins is one of the important research areas in proteomics. Herein, a simple and rapid method is established to screen small ligands that bind to proteins. We designed an agarose slide to immobilize different proteins. The protein microarrays were allowed to interact with different small ligands, and after washing, the microarrays were screened by desorption electrospray ionization mass spectrometry (DESI MS). This method can be applied to screen specific protein binding ligands and was shown for seven proteins and 34 known ligands for these proteins. In addition, a high-throughput screening was achieved, with the analysis requiring approximately 4 s for one sample spot. We then applied this method to determine the binding between the important protein matrix metalloproteinase-9 (MMP-9) and 88 small compounds. The molecular docking results confirmed the MS results, demonstrating that this method is suitable for the rapid and accurate screening of ligands binding to proteins. Graphical Abstract ᅟ. PMID:26174365

  20. Evaluation of laser diode thermal desorption-tandem mass spectrometry (LDTD-MS-MS) in forensic toxicology.

    PubMed

    Bynum, Nichole D; Moore, Katherine N; Grabenauer, Megan

    2014-10-01

    Many forensic laboratories experience backlogs due to increased drug-related cases. Laser diode thermal desorption (LDTD) has demonstrated its applicability in other scientific areas by providing data comparable with instrumentation, such as liquid chromatography-tandem mass spectrometry, in less time. LDTD-MS-MS was used to validate 48 compounds in drug-free human urine and blood for screening or quantitative analysis. Carryover, interference, limit of detection, limit of quantitation, matrix effect, linearity, precision and accuracy and stability were evaluated. Quantitative analysis indicated that LDTD-MS-MS produced precise and accurate results with the average overall within-run precision in urine and blood represented by a %CV <14.0 and <7.0, respectively. The accuracy for all drugs in urine ranged from 88.9 to 104.5% and 91.9 to 107.1% in blood. Overall, LDTD has the potential for use in forensic toxicology but before it can be successfully implemented that there are some challenges that must be addressed. Although the advantages of the LDTD system include minimal maintenance and rapid analysis (∼10 s per sample) which makes it ideal for high-throughput forensic laboratories, a major disadvantage is its inability or difficulty analyzing isomers and isobars due to the lack of chromatography without the use of high-resolution MS; therefore, it would be best implemented as a screening technique. PMID:25217542

  1. Direct Analysis of Triacylglycerols from Crude Lipid Mixtures by Gold Nanoparticle-Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Son, Jeongjin; Lee, Gwangbin; Cha, Sangwon

    2014-05-01

    Triacylglycerols (TAGs), essential energy storage lipids, are easily detected by conventional MALDI MS when occurring on their own. However, their signals are easily overwhelmed by other lipids, mainly phosphatidylcholines (PCs) and, therefore, require purification. In order to profile TAGs from crude lipid mixtures without prefractionation, we investigated alternative matrixes that can suppress phospholipid ion signals and enhance cationization of TAGs. We found that an aqueous solution of citrate-capped gold nanoparticles (AuNPs) with a diameter of 12 nm is a superior matrix for the laser desorption/ionization mass spectrometry (LDI MS) of TAGs in crude lipid mixtures. The AuNP matrix effectively suppressed other lipid signals such as phospholipids and also provided 100 times lower detection limit for TAGs than 2,5-dihydroxybenzoic acid (DHB), the best conventional MALDI matrix for TAGs. The AuNP-assisted LDI MS enabled us to obtain detailed TAG profiles including minor species directly from crude beef lipid extracts without phospholipid interference. In addition, we could detect TAGs at a trace level from a total brain lipid extract.

  2. Mass spectrometry detection and imaging of inorganic and organic explosive device signatures using desorption electro-flow focusing ionization.

    PubMed

    Forbes, Thomas P; Sisco, Edward

    2014-08-01

    We demonstrate the coupling of desorption electro-flow focusing ionization (DEFFI) with in-source collision induced dissociation (CID) for the mass spectrometric (MS) detection and imaging of explosive device components, including both inorganic and organic explosives and energetic materials. We utilize in-source CID to enhance ion collisions with atmospheric gas, thereby reducing adducts and minimizing organic contaminants. Optimization of the MS signal response as a function of in-source CID potential demonstrated contrasting trends for the detection of inorganic and organic explosive device components. DEFFI-MS and in-source CID enabled isotopic and molecular speciation of inorganic components, providing further physicochemical information. The developed system facilitated the direct detection and chemical mapping of trace analytes collected with Nomex swabs and spatially resolved distributions within artificial fingerprints from forensic lift tape. The results presented here provide the forensic and security sectors a powerful tool for the detection, chemical imaging, and inorganic speciation of explosives device signatures. PMID:24968206

  3. Lipid imaging within the normal rat kidney using silver nanoparticles by matrix-assisted laser desorption/ionization mass spectrometry

    PubMed Central

    Muller, Ludovic; Kailas, Ajay; Jackson, Shelley N.; Roux, Aurelie; Barbacci, Damon; Schultz, J. Albert; Balaban, Carey; Woods, Amina S.

    2015-01-01

    The well-characterized cellular and structural components of the kidney show distinct regional compositions and distribution of lipids. In order to more fully analyze the renal lipidome we developed a matrix-assisted laser desorption/ionization mass spectrometry approach for imaging that may be used to pinpoint sites of changes from normal in pathological conditions. This was accomplished by implanting sagittal cryostat rat kidney sections with a stable, quantifiable and reproducible uniform layer of silver using a magnetron sputtering source to form silver nanoparticles. Thirty-eight lipid species including 7 ceramides, 8 diacylglycerols, 22 triacylglycerols, and cholesterol were detected and imaged in positive ion mode. Thirty-six lipid species consisting of, 7 sphingomyelins, 10 phosphatidylethanolamines, 1 phosphatidylglycerol, 7 phosphatidylinositols and 11 sulfatides, were imaged in negative ion mode for a total of seventy-four high resolution lipidome maps of the normal kidney. Thus, our approach is a powerful tool not only for studying structural changes in animal models of disease, but also for diagnosing and tracking stages of disease in human kidney tissue biopsies. PMID:25671768

  4. Rapid characterization of complex viscous samples at molecular levels by neutral desorption extractive electrospray ionization mass spectrometry.

    PubMed

    Li, Xue; Hu, Bin; Ding, Jianhua; Chen, Huanwen

    2011-07-01

    In this protocol, the sample (which could be a bulk or heterogeneous fluid, or a greasy surface) is treated with a neutral desorption (ND) sampling gas beam, and the resulting analyte mixtures are directly characterized by extractive electrospray ionization mass spectrometry (EESI-MS). The ND device can be specifically constructed such that the sampling gas beam is bubbled through the liquid sample (microjet sampling) or directed to impact the sample surface (e.g., for the analysis of a material like cheese). The ND-EESI-MS analysis process requires no sample pretreatment because it can tolerate an extremely complex matrix. ND-EESI-MS allows real-time, online chemical profiling of highly viscous samples under ambient conditions. Both volatile and nonvolatile analytes from viscous samples can easily be detected and quantified by ND-EESI-MS, thereby providing an MS-based analytical platform for multiple disciplines (e.g., for the food industry, for drug discovery, and for the biological and life sciences). Here we describe the ND-EESI-MS protocol for viscous sample analysis, including the experimental design, equipment setup, reagent preparation, data acquisition and analysis steps. The data collection process takes <1 min per sample, although the time required for the whole procedure, which largely depends on the experimental preparation processes, might be considerably longer. PMID:21720314

  5. Identification of phlebotomine sand flies (Diptera: Psychodidae) by matrix-assisted laser desorption/ionization time of flight mass spectrometry

    PubMed Central

    2014-01-01

    Background Phlebotomine sand flies are incriminated in the transmission of several human and veterinary pathogens. To elucidate their role as vectors, proper species identification is crucial. Since traditional morphological determination is based on minute and often dubious characteristics on their head and genitalia, which require certain expertise and may be damaged in the field-collected material, there is a demand for rapid, simple and cost-effective molecular approaches. Methods Six laboratory-reared colonies of phlebotomine sand flies belonging to five species and four subgenera (Phlebotomus, Paraphlebotomus, Larroussius, Adlerius) were used to evaluate the discriminatory power of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Various storage conditions and treatments, including the homogenization in either distilled water or given concentrations of formic acid, were tested on samples of both sexes. Results Specimens of all five analysed sand fly species produced informative, reproducible and species-specific protein spectra that enabled their conclusive species identification. The method also distinguished between two P. sergenti colonies originating from different geographical localities. Protein profiles within a species were similar for specimens of both sexes. Tested conditions of specimen storage and sample preparation give ground to a standard protocol that is generally applicable on analyzed sand fly specimens. Conclusions Species identification of sand flies by MALDI-TOF MS is feasible and represents a novel promising tool to improve biological and epidemiological studies on these medically important insects. PMID:24423215

  6. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  7. Glycine Identification in Natural Jarosites Using Laser Desorption Fourier Transform Mass Spectrometry: Implications for the Search for Life on Mars

    NASA Astrophysics Data System (ADS)

    Kotler, J. Michelle; Hinman, Nancy W.; Yan, Beizhan; Stoner, Daphne L.; Scott, Jill R.

    2008-04-01

    The jarosite group minerals have received increasing attention since the discovery of jarosite on the martian surface by the Mars Exploration Rover Opportunity. Given that jarosite can incorporate foreign ions within its structure, we have investigated the use of jarosite as an indicator of aqueous and biological processes on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide. One of the ions from the natural jarosites has been attributed to glycine because it was systematically observed in combinations of glycine with synthetic ammonium and potassium jarosites, Na2SO4 and K2SO4. The ability to observe these organic signatures in jarosite samples with an in situ instrumental technique, such as the one employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  8. 2-Hydrazinoquinoline: a reactive matrix for matrix-assisted laser desorption/ionization mass spectrometry to detect gaseous carbonyl compounds.

    PubMed

    Shigeri, Yasushi; Kamimura, Takuya; Ando, Masanori; Uegaki, Koichi; Sato, Hiroaki; Tani, Fumito; Arakawa, Ryuichi; Kinumi, Tomoya

    2016-01-01

    The sensitivity, range of applications, and reaction mechanism of 2-hydrazinoquinoline as a reactive matrix for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were examined. Using a reaction chamber (125L) equipped with a stirring fan and a window for moving the MALDI-MS plate and volatile samples in and out, the sensitivities of 2-hydrazinoquinoline to gaseous aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and n-butyraldehyde) and ketones (acetone, methyl ethyl ketone, and methyl isobutyl ketone) were determined to be at least parts per million (ppm) levels. On the other hand, carboxylic acids (formic acid, acetic acid, propionic acid, and butyric acid) and esters (ethyl acetate, pentyl acetate, isoamyl acetate, and methyl salicylate) could not be detected by 2-hydrazinoquinoline in MALDI-MS. In addition to 2,4-dinitrophenylhydrazine, a common derivatization reagent for analyzing carbonyl compounds quantitatively in gas chromatography and liquid chromatography, the dissolution of 2-hydrazinoquinoline in an acidic solution, such as trifluoroacetic acid, was essential for its function as a reactive matrix for MALDI- MS. PMID:27419901

  9. TOPICAL REVIEW: Breathing mode excitation in near-harmonic systems: resonant mass capture, desorption and atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Gadzuk, J. W.

    1998-09-01

    The phenomenon of breathing mode excitation or bound-state wavepacket squeezing and spreading driven by a time-dependent oscillator frequency (due to either a transient force constant or mass) is considered here. An easily implemented theory of stimulated wavepacket dynamics for near-harmonic systems is presented which describes a variety of generic time dependences such as single sudden excitation, double switching (excitation/time delay/de-excitation) and decaying initially excited states which characterize many processes in spectroscopy, pump-probe control in intramolecular dynamics, and femtochemistry. The model is used as the theoretical basis for understanding such diverse phenomena as quantum excitation due to temporary neutron capture, stimulated bond-breaking resulting in delocalization, desorption, or dissociation, and breathing mode excitation of ultracold atoms trapped in optical lattices. Whilst the first two examples are speculative, results for transient wavepacket dynamics of the occupied excited optical lattice are in accord with recent experimental observations reported by the NIST Laser Cooling Group. Emphasis on the inherent theoretical simplicity and the multidisciplinary aspects of near-harmonic breathing mode excitation, as exemplified by the specific realizations considered here, has been a major intent of this topical review.

  10. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-07-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  11. Differentiation of Aeromonas isolated from drinking water distribution systems using matrix-assisted laser desorption/ionization-mass spectrometry.

    PubMed

    Donohue, Maura J; Best, Jennifer M; Smallwood, Anthony W; Kostich, Mitchell; Rodgers, Mark; Shoemaker, Jody A

    2007-03-01

    The genus Aeromonas is one of several medically significant genera that have gained prominence due to their evolving taxonomy and controversial role in human diseases. In this study, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was used to analyze the whole cells of both reference strains and unknown Aeromonas isolates obtained from water distribution systems. A library of over 45 unique m/z signatures was created from 40 strains that are representative of the 17 recognized species of Aeromonas, as well as 3 reference strains from genus Vibrio and 2 reference strains from Plesiomonas shigelloides. The library was used to help speciate 52 isolates of Aeromonas. The environmental isolates were broken up into 2 blind studies. Group 1 contained isolates that had a recognizable phenotypic profile and group 2 contained isolates that had an atypical phenotypic profile. MALDI-MS analysis of the water isolates in group 1 matched the phenotypic identification in all cases. In group 2, the MALDI-MS-based determination confirmed the identity of 18 of the 27 isolates. These results demonstrate that MALDI-MS analysis can rapidly and accurately classify species of the genus Aeromonas, making it a powerful tool especially suited for environmental monitoring and detection of microbial hazards in drinking water. PMID:17269751

  12. Identification and Imaging of Peptides and Proteins on Enterococcus faecalis Biofilms by Matrix Assisted Laser Desorption Ionization Mass Spectrometry

    PubMed Central

    Melvin Blaze, M. T.; Aydin, Berdan; Carlson, Ross; Hanley, Luke

    2013-01-01

    The heptapeptide ARHPHPH was identified from biofilms and planktonic cultures of two different strains of Enterococcus faecalis, V583 and ATCC 29212, using matrix assisted laser desorption ionization mass spectrometry (MALDI-MS). ARHPHPH was also imaged at the boundary of cocultured, adjacent E. faecalis and Escherichia coli (ATCC 25922) biofilms, appearing only on the E. faecalis side. ARHPHPH was proteolyzed from κ-casein, a component in the growth media, by E. faecalis microbes. Additionally, top down and bottom up proteomic approaches were combined to identify and spatially locate multiple proteins within intact E. faecalis V583 biofilms by MALDI-MS. The resultant tandem MS data were searched against the NCBInr E. faecalis V583 database to identify thirteen cytosolic and membrane proteins which have functional association with the cell surface. Two of these proteins, enolase and GAPDH, are glycolytic enzymes known to display multiple functions in bacterial virulence in related bacterial strains. This work illustrates a powerful approach for discovering and localizing multiple peptides and proteins within intact biofilms. PMID:22962657

  13. Peptide Profiling Using Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight Mass Spectrometry for Identification of Animal Fibers

    PubMed Central

    Izuchi, Yukari; Tokuhara, Mutsumi; Takashima, Tsuneo; Kuramoto, Kanya

    2013-01-01

    Identification of fibers for verification of their specific animal origin is necessary for maintaining quality and value in the clothing industry. In order to examine adulteration in animal fibers, there is a commercially accepted method of microscopy analysis. However, this method is subjective and time-consuming due to its reliance on an operator identifying magnified fibers from their scale image and other features. Therefore, alternative reliable identification methods are required. In this study, peptide analysis using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOFMS) is presented and used to distinguish between cashmere, wool, mohair, yak, camel, angora, and alpaca in untreated and treated fibers (dyed, chlorinated wool). Typical m/z values for each specific type of animal fiber were identified. Predictive models that could identify seven types of animal fibers as well as 50% blended samples were successfully constructed using multivariate analyses such as PCA and PLS regression. This technique is therefore extremely useful for complementing the conventional tests for detecting adulteration in animal fiber fabrics and clothing. PMID:24860713

  14. Differentiation of Microbial Species and Strains in Coculture Biofilms by Multivariate Analysis of Laser Desorption Postionization Mass Spectra

    PubMed Central

    Bhardwaj, Chhavi; Cui, Yang; Hofstetter, Theresa; Liu, Suet Yi; Bernstein, Hans C.; Carlson, Ross P.; Ahmed, Musahid; Hanley, Luke

    2013-01-01

    7.87 to 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze biofilms comprised of binary cultures of interacting microorganisms. The effect of photon energy was examined using both tunable synchrotron and laser sources of VUV radiation. Principal components analysis (PCA) was applied to the MS data to differentiate species in Escherichia coli-Saccharomyces cerevisiae coculture biofilms. PCA of LDPI-MS also differentiated individual E. coli strains in a biofilm comprised of two interacting gene deletion strains, even though these strains differed from the wild type K-12 strain by no more than four gene deletions each out of approximately 2000 genes. PCA treatment of 7.87 eV LDPI-MS data separated the E. coli strains into three distinct groups, two “pure” groups, and a mixed region. Furthermore, the “pure” regions of the E. coli cocultures showed greater variance by PCA at 7.87 eV photon energies compared to 10.5 eV radiation. This is consistent with the expectation that the 7.87 eV photoionization selects a subset of low ionization energy analytes while 10.5 eV is more inclusive, detecting a wider range of analytes. These two VUV photon energies therefore give different spreads via PCA and their respective use in LDPI-MS constitute an additional experimental parameter to differentiate strains and species. PMID:24067765

  15. Rapid identification of siderophores by combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Hayen, Heiko; Volmer, Dietrich A

    2005-01-01

    The investigation of a combined thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry (TLC/MALDI-MS) method for the analysis of siderophores from microbial samples is described. The investigated siderophores were enterobactin, ferrioxamine B, ferrichrome, ferrirhodin, rhodotorulic acid and coprogen. Solid-phase extraction was employed to recover the siderophores from the microbial samples. After visualization of the spots via spraying with ferric chloride or chrome azurol sulfonate assay solution, the MALDI matrix was applied to the gel surface. Several TLC/MALDI experimental parameters were optimized, such as type and concentration of MALDI matrix, as well as the type and composition of solvent to facilitate analyte transport from the inside of the TLC gel to the surface. The impact of these parameters on sensitivity, precision and ion formation of the various siderophores was studied. The detection limits for the investigated siderophores were in the range 1-4 pmol. These values were about 4-24 times higher than the detection limits obtained directly from stainless steel MALDI targets. The differences were most likely due to incomplete transport of the 'trapped' analyte molecules from the deeper layers of the TLC gel to the surface and into the matrix layer. In addition, chromatographic band broadening spread the analyte further in TLC as compared with the steel plates, resulting in less analyte per surface area. The identification of the siderophores was aided by concurrently applying a Ga(III) nitrate solution to the TLC plate during the visualization step. The resulting formation of Ga(III) complexes lead to distinctive (69)Ga/(71)Ga isotope patterns in the mass spectra. The versatility of the TLC/MALDI-MS assay was demonstrated by using it to analyze siderophores in a Pseudomonas aeruginosa sample. An iron-binding compound was identified in the sample, namely pyochelin (2-(2-o-hydroxyphenyl-2-thiazolin-4-yl)-3

  16. A binary matrix for improved detection of phosphopeptides in matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Zhou, Li-Hua; Kang, Gum-Yong; Kim, Kwang Pyo

    2009-08-01

    Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analysis and characterization of phosphopeptides in peptide mixtures may have a limitation, because of the lower ionizing efficiency of phosphopeptides than nonphosphorylated peptides in MALDI MS. In this work, a binary matrix that consists of two conventional matrices of 3-hydroxypicolinic acid (3-HPA) and alpha-cyano-4-hydroxycinnamic acid (CCA) was tested for phosphopeptide analysis. 3-HPA and CCA were found to be hot matrices, and 3-HPA not as good as CCA and 2,5-dihydroxybenzoic acid (DHB) for peptide analysis. However, the presence of 3-HPA in the CCA solution with a volume ratio of 1:1 could significantly enhance ion signals for phosphopeptides in both positive-ion and negative-ion detection modes compared with the use of pure CCA or DHB, the most common phosphopeptide matrices. Higher signal intensities of phosphopeptides could be obtained with lower laser power using the binary matrix. Neutral loss of the phosphate group (-80 Da) and phosphoric acid (-98 Da) from the phosphorylated-residue-containing peptide ions with the binary matrix was decreased compared with CCA alone. In addition, since the crystal shape prepared with the binary matrix was more homogeneous than that prepared with DHB, searching for 'sweet' spots can be avoided. The sensitivity to detect singly or doubly phosphorylated peptides in peptide mixtures was higher than that obtained with pure CCA and as good as that obtained using DHB. We also used the binary matrix to detect the in-solution tryptic digest of the crude casein extracted from commercially available low fat milk sample, and found six phosphopeptides to match the digestion products of casein, based on mass-to-charge values and LIFT TOF-TOF spectra. PMID:19551845

  17. Characterization of pyrogenic black carbon by desorption atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Podgorski, David C; Hamdan, Rasha; McKenna, Amy M; Nyadong, Leonard; Rodgers, Ryan P; Marshall, Alan G; Cooper, William T

    2012-02-01

    We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C and O/C ratios. The bimodal distribution of aromatic and aliphatic compounds observed in the combusted oak sample is attributed to incomplete thermal degradation of lignin and hemicellulose. Pyrolyzed oak constituents exhibit lower H/C and O/C ratios: approximately three-quarters of the identified species are aromatic. DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy. Complete molecular characterization of biomass upon thermal transformation may provide insight into the biogeochemical cycles of biochar and future renewable energy sources, particularly for samples currently limited by solubility, separation, and sample preparation. PMID:22242739

  18. Removal of sodium dodecyl sulfate from protein samples prior to matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Puchades, M; Westman, A; Blennow, K; Davidsson, P

    1999-01-01

    Sodium dodecyl sulfate (SDS) is widely used for protein solubilization and for separation of proteins by SDS polyacrylamide gel electrophoresis (SDS-PAGE). However, SDS interferes with other techniques used for characterization of proteins, such as mass spectrometry (MS) and amino acid sequencing. In this paper, we have compared three procedures to remove SDS from proteins, including chloroform/methanol/water extraction (C/M/W), cold acetone extraction and desalting columns, in order to find a rapid and reproducible procedure that provides sufficient reduction of SDS and high recovery rates for proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). A 1000-fold reduction of SDS concentration and a protein recovery at approximately 50% were obtained with the C/M/W procedure. The cold acetone procedure gave a 100-fold reduction of SDS and a protein recovery of approximately 80%. By using desalting columns, the removal of SDS was 100-fold, with a protein recovery of nearly 50%. Both the C/M/W and the cold acetone methods provided sufficient reduction of SDS, high recovery rates of protein and allowed the acquisition of MALDI spectra. The use of n-octyl-beta-D-glucopyranoside in the protein sample preparation enhanced the MALDI signal for protein samples containing more than 2 10(-4)% SDS, after the C/M/W extraction. Following the cold acetone procedure, the use of n-octylglucoside was found to be necessary in order to obtain spectra, but they were of lower quality than those obtained with the C/M/W method, probably due to higher residual amounts of SDS. PMID:10209872

  19. Self-aliquoting microarray plates for accurate quantitative matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Pabst, Martin; Fagerer, Stephan R; Köhling, Rudolf; Küster, Simon K; Steinhoff, Robert; Badertscher, Martin; Wahl, Fabian; Dittrich, Petra S; Jefimovs, Konstantins; Zenobi, Renato

    2013-10-15

    Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a fast analysis tool employed for the detection of a broad range of analytes. However, MALDI-MS has a reputation of not being suitable for quantitative analysis. Inhomogeneous analyte/matrix co-crystallization, spot-to-spot inhomogeneity, as well as a typically low number of replicates are the main contributing factors. Here, we present a novel MALDI sample target for quantitative MALDI-MS applications, which addresses the limitations mentioned above. The platform is based on the recently developed microarray for mass spectrometry (MAMS) technology and contains parallel lanes of hydrophilic reservoirs. Samples are not pipetted manually but deposited by dragging one or several sample droplets with a metal sliding device along these lanes. Sample is rapidly and automatically aliquoted into the sample spots due to the interplay of hydrophilic/hydrophobic interactions. With a few microliters of sample, it is possible to aliquot up to 40 replicates within seconds, each aliquot containing just 10 nL. The analyte droplet dries immediately and homogeneously, and consumption of the whole spot during MALDI-MS analysis is typically accomplished within few seconds. We evaluated these sample targets with respect to their suitability for use with different samples and matrices. Furthermore, we tested their application for generating calibration curves of standard peptides with α-cyano-4-hdydroxycinnamic acid as a matrix. For angiotensin II and [Glu(1)]-fibrinopeptide B we achieved coefficients of determination (r(2)) greater than 0.99 without the use of internal standards. PMID:24003910

  20. Identification of beer-spoilage bacteria using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Wieme, Anneleen D; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita; Vandamme, Peter

    2014-08-18

    Applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of beer-spoilage bacteria was examined. To achieve this, an extensive identification database was constructed comprising more than 4200 mass spectra, including biological and technical replicates derived from 273 acetic acid bacteria (AAB) and lactic acid bacteria (LAB), covering a total of 52 species, grown on at least three growth media. Sequence analysis of protein coding genes was used to verify aberrant MALDI-TOF MS identification results and confirmed the earlier misidentification of 34 AAB and LAB strains. In total, 348 isolates were collected from culture media inoculated with 14 spoiled beer and brewery samples. Peak-based numerical analysis of MALDI-TOF MS spectra allowed a straightforward species identification of 327 (94.0%) isolates. The remaining isolates clustered separately and were assigned through sequence analysis of protein coding genes either to species not known as beer-spoilage bacteria, and thus not present in the database, or to novel AAB species. An alternative, classifier-based approach for the identification of spoilage bacteria was evaluated by combining the identification results obtained through peak-based cluster analysis and sequence analysis of protein coding genes as a standard. In total, 263 out of 348 isolates (75.6%) were correctly identified at species level and 24 isolates (6.9%) were misidentified. In addition, the identification results of 50 isolates (14.4%) were considered unreliable, and 11 isolates (3.2%) could not be identified. The present study demonstrated that MALDI-TOF MS is well-suited for the rapid, high-throughput and accurate identification of bacteria isolated from spoiled beer and brewery samples, which makes the technique appropriate for routine microbial quality control in the brewing industry. PMID:24929682

  1. Improved analysis of membrane protein by PVDF-aided, matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Chang, Chih-Yang; Liao, Hsin-Kai; Juo, Chiun-Gung; Chen, Shu-Hua; Chen, Yu-Ju

    2006-01-18

    Characterization of membrane proteins remains an analytical challenge because of difficulties associated with tedious isolation and purification. This study presents the utility of the polyvinylidene difluoride (PVDF) membrane for direct sub-proteome profiling and membrane protein characterization by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The hydrophobic adsorption of protein, particularly membrane proteins, on the PVDF surface enables efficient on-PVDF washing to remove high concentrations of detergents and salts, such as up to 5% sodium dodecyl sulfate (SDS). The enhanced spectrum quality for MALDI detection is particularly notable for high molecular weight proteins. By using on-PVDF washing prior to MALDI detection, we obtained protein profiles of the detergent-containing and detergent-insoluble membrane fractions from Methylococcus capsulatus (Bath). Similar improvements of signal-to-noise ratios were shown on the MALDI spectra for proteins electroblotted from SDS-polyacrylamide gel electrophoresis (SDS-PAGE) onto the PVDF membrane. We have applied this strategy to obtain intact molecular weights of the particulate methane monooxygenase (pMMO) composed of three intrinsic membrane-bound proteins, PmoA, PmoB, and PmoC. Together with peptide sequencing by tandem mass spectrometry, post-translational modifications including N-terminal acetylation of PmoA and PmoC and alternative C-terminal truncation of PmoB were identified. The above results show that PVDF-aided MALDI-MS can be an effective approach for profiling and characterization of membrane proteins. PMID:17723354

  2. Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    PubMed Central

    Mayer-Scholl, Anne; Murugaiyan, Jayaseelan; Neumann, Jennifer; Bahn, Peter; Reckinger, Sabine; Nöckler, Karsten

    2016-01-01

    Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP) representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology. PMID:26999436

  3. Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

    PubMed

    Mayer-Scholl, Anne; Murugaiyan, Jayaseelan; Neumann, Jennifer; Bahn, Peter; Reckinger, Sabine; Nöckler, Karsten

    2016-01-01

    Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP) representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology. PMID:26999436

  4. Trace detection of non-uniformly distributed analytes on surfaces using mass transfer and large-area desorption electrospray ionization (DESI) mass spectrometry.

    PubMed

    Soparawalla, Santosh; Salazar, Gary A; Sokol, Ewa; Perry, Richard H; Cooks, R Graham

    2010-08-01

    Ambient ionization methods such as desorption electrospray ionization (DESI) allow the analysis of chemicals adsorbed at surfaces without the need for sample (or surface) pretreatment. A limitation of current implementations of these ionization sources is the small size of the area that can be sampled. This makes examination of surfaces of large areas time-consuming because of the need to raster across the surface. This paper describes a DESI source that produces a spray plume with an effective desorption/ionization area of 3.6 cm(2), some 200 times larger than given by conventional DESI sources. Rhodamine 6G and several drugs of abuse (codeine, heroin and diazepam) were used to demonstrate the ability to use large-area DESI MS to perform rapid (a few seconds) representative sampling of areas of the order of several square centimetres without scanning the probe across the surface. The large area ion source displayed high sensitivity (limits of detection in the high nanogram range) and high reproducibility (approximately 20 to 35% relative standard deviation). The rapid analysis of even larger surfaces (hundreds of cm(2)) for traces of explosives is possible using a sorbent surface wipe followed by large-area DESI interrogation performed directly on the wipe material. The performance of this mass transfer dry wipe method was examined by determination of the limits of detection of several explosives. Surfaces with different topographies and compositions were also tested. Using this method, absolute limits of detection observed for HMX and RDX from plastic surfaces and skin were found to be as low as 10 ng cm(-2). The concentration of residue from large surface areas in this technique allowed the detection of 100 ng of explosives from surfaces with areas ranging from 1.00 x 10(3) cm(2) to 1.40 x 10(4) cm(2). PMID:20539884

  5. Two-Step Resonance-Enhanced Desorption Laser Mass Spectrometry for In Situ Analysis of Organic-Rich Environments

    NASA Technical Reports Server (NTRS)

    Getty, S. A.; Grubisic, A.; Uckert, K.; Li, X.; Cornish, T.; Cook, J. E.; Brinckerhoff, W. B.

    2016-01-01

    A wide diversity of planetary surfaces in the solar system represent high priority targets for in situ compositional and contextual analysis as part of future missions. The planned mission portfolio will inform our knowledge of the chemistry at play on Mars, icy moons, comets, and primitive asteroids, which can lead to advances in our understanding of the interplay between inorganic and organic building blocks that led to the evolution of habitable environments on Earth and beyond. In many of these environments, the presence of water or aqueously altered mineralogy is an important indicator of habitable environments that are present or may have been present in the past. As a result, the search for complex organic chemistry that may imply the presence of a feedstock, if not an inventory of biosignatures, is naturally aligned with targeted analyses of water-rich surface materials. Here we describe the two-step laser mass spectrometry (L2MS) analytical technique that has seen broad application in the study of organics in meteoritic samples, now demonstrated to be compatible with an in situ investigation with technique improvements to target high priority planetary environments as part of a future scientific payload. An ultraviolet (UV) pulsed laser is used in previous and current embodiments of laser desorption/ionization mass spectrometry (LDMS) to produce ionized species traceable to the mineral and organic composition of a planetary surface sample. L2MS, an advanced technique in laser mass spectrometry, is selective to the aromatic organic fraction of a complex sample, which can provide additional sensitivity and confidence in the detection of specific compound structures. Use of a compact two-step laser mass spectrometer prototype has been previously reported to provide specificity to key aromatic species, such as PAHs, nucleobases, and certain amino acids. Recent improvements in this technique have focused on the interaction between the mineral matrix and the

  6. Performance and Cost Analysis of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Routine Identification of Yeast▿

    PubMed Central

    Dhiman, Neelam; Hall, Leslie; Wohlfiel, Sherri L.; Buckwalter, Seanne P.; Wengenack, Nancy L.

    2011-01-01

    Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry was compared to phenotypic testing for yeast identification. MALDI-TOF mass spectrometry yielded 96.3% and 84.5% accurate species level identifications (spectral scores, ≥1.8) for 138 common and 103 archived strains of yeast. MALDI-TOF mass spectrometry is accurate, rapid (5.1 min of hands-on time/identification), and cost-effective ($0.50/sample) for yeast identification in the clinical laboratory. PMID:21270234

  7. Determination of Macrolide Antibiotics Using Dispersive Liquid-Liquid Microextraction Followed by Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, Kuan-Yu; Yang, Thomas C.; Chang, Sarah Y.

    2012-06-01

    A novel method for the determination of macrolide antibiotics using dispersive liquid-liquid microextraction coupled to surface-assisted laser desorption/ionization mass spectrometric detection was developed. Acetone and dichloromethane were used as the disperser solvent and extraction solvent, respectively. A mixture of extraction solvent and disperser solvent were rapidly injected into a 1.0 mL aqueous sample to form a cloudy solution. After the extraction, macrolide antibiotics were detected using surface-assisted laser desorption/ionization mass spectrometry (SALDI/MS) with colloidal silver as the matrix. Under optimum conditions, the limits of detection (LODs) at a signal-to-noise ratio of 3 were 2, 3, 3, and 2 nM for erythromycin (ERY), spiramycin (SPI), tilmicosin (TILM), and tylosin (TYL), respectively. This developed method was successfully applied to the determination of macrolide antibiotics in human urine samples.

  8. Enzyme-Coupled Nanoparticles-Assisted Laser Desorption Ionization Mass Spectrometry for Searching for Low-Mass Inhibitors of Enzymes in Complex Mixtures

    NASA Astrophysics Data System (ADS)

    Salwiński, Aleksander; Da Silva, David; Delépée, Raphaël; Maunit, Benoît

    2014-04-01

    In this report, enzyme-coupled magnetic nanoparticles (EMPs) were shown to be an effective affinity-based tool for finding specific interactions between enzymatic targets and the low-mass molecules in complex mixtures using classic MALDI-TOF apparatus. EMPs used in this work act as nonorganic matrix enabling ionization of small molecules without any interference in the low-mass range (enzyme-coupled nanoparticles-assisted laser desorption ionization MS, ENALDI MS) and simultaneously carry the superficial specific binding sites to capture inhibitors present in a studied mixture. We evaluated ENALDI approach in two complementary variations: `ion fading' (IF-ENALDI), based on superficial adsorption of inhibitors and `ion hunting' (IH-ENALDI), based on selective pre-concentration of inhibitors. IF-ENALDI was applied for two sets of enzyme-inhibitor pairs: tyrosinase-glabridin and trypsin-leupeptin and for the real plant sample: Sparrmannia discolor leaf and stem methanol extract. The efficacy of IH-ENALDI was shown for the pair of trypsin-leupeptin. Both ENALDI approaches pose an alternative for bioassay-guided fractionation, the common method for finding inhibitors in the complex mixtures.

  9. BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

    SciTech Connect

    Steele, P T

    2004-07-20

    Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and ionization (DI) system. The mass spectra produced by early proof-of-concept instruments were highly variable and contained limited information to differentiate certain types of similar biological particles. The investigation of this variability and subsequent changes to the DI laser system are described. The modifications have reduced the observed variability and thereby increased the usable information content in the spectra. These improvements would have little value without software to analyze and identify the mass spectra. Important improvements have been made to the algorithms that initially processed and analyzed the data. Single particles can be identified with an impressive level of accuracy, but to obtain significant reductions in the overall false alarm rate of the BAMS instrument, alarm decisions must be made dynamically on the basis of multiple analyzed particles. A statistical model has been developed to make these decisions and the resulting performance of a hypothetical BAMS system is quantitatively predicted. The predictions indicate that a BAMS system, with reasonably attainable characteristics, can operate with a very low false alarm rate (orders of magnitude lower than some currently fielded biodetectors) while still being sensitive to small concentrations of biological particles in a large range of environments. Proof-of-concept instruments, incorporating some of the modifications described here, have already performed well in independent testing.

  10. An experimental and modeling study of grain-scale uranium desorption from field-contaminated sediments and the potential influence of microporosity on mass-transfer

    NASA Astrophysics Data System (ADS)

    Stoliker, D.; Liu, C.; Kent, D. B.; Zachara, J. M.

    2012-12-01

    The aquifer below the 300-Area of the Hanford site (Richland, WA, USA) is plagued by a persistent plume of dissolved uranium (U(VI)) in excess of the Environmental Protection Agency drinking water maximum contamination level even after the removal of highly contaminated sediments. The aquifer sediments in the seasonally saturated lower vadose zone act as both a source and sink for uranium during stage changes in the nearby Columbia River. Diffusion limitation of uranium mass-transfer within these sediments has been cited as a potential cause of the plume's persistence. Equilibrium U(VI) sorption is a strong function of variable chemical conditions, especially carbonate, hydrogen, and uranyl ion activities. Field-contaminated sediments from the site require up to 1,000 hours to reach equilibrium in static batch reactors. Increases in U(VI) concentrations over longer time-scales result from changes in chemical conditions, which drive reactions with sediments that favor U(VI) desorption. Grain-scale U(VI) sorption/desorption rates are slow, likely owing to diffusion of U(VI) and other solutes through intra-granular pore domains. In order to improve understanding of the impact of intra-granular diffusion and chemical reactions controlling grain-scale U(VI) release, experiments were conducted on individual particle size fractions of a <8 mm composite of field-contaminated, lower vadose zone sediments. For each size fraction, equilibrium U(VI) sorption/desorption in static batch reactors was well-described by surface complexation models over a range of chemical conditions applicable to the field site. Desorption rates from individual size fractions in flow-through batch reactors, examined under a single set of constant chemical conditions with multiple stop-flow events, were similar for all size fractions <2 mm. Kinetic U(VI) desorption in flow-through batch reactors was modeled using a multi-rate surface complexation approach, where sorption/desorption rates were

  11. Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for species identification of nonfermenting Gram-negative bacilli.

    PubMed

    Almuzara, Marisa; Barberis, Claudia; Traglia, Germán; Famiglietti, Angela; Ramirez, Maria Soledad; Vay, Carlos

    2015-05-01

    Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) to identify 396 Nonfermenting Gram-Negative Bacilli clinical isolates was evaluated in comparison with conventional phenotypic tests and/or molecular methods. MALDI-TOF MS identified to species level 256 isolates and to genus or complex level 112 isolates. It identified 29 genera including uncommon species. PMID:25765149

  12. Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Blood Isolates of Acinetobacter Species

    PubMed Central

    Hsueh, Po-Ren; Kuo, Lu-Cheng; Chang, Tsung-Chain; Lee, Tai-Fen; Teng, Shih-Hua; Chuang, Yu-Chung; Teng, Lee-Jene

    2014-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper) was able to accurately identify 98.6% (142/144) of Acinetobacter baumannii isolates, 72.4% (63/87) of A. nosocomialis isolates, and 97.6% (41/42) of A. pittii isolates. All Acinetobacter junii, A. ursingii, A. johnsonii, and A. radioresistens isolates (n = 28) could also be identified correctly by Bruker Biotyper. PMID:24899038

  13. Phenotypic Detection of Carbapenemase-Producing Enterobacteriaceae by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and the Carba NP Test

    PubMed Central

    Jadhav, Snehal; Sevior, Danielle; Agyekum, Alex; Whipp, Margaret; Waring, Lynette; Iredell, Jonathan; Palombo, Enzo

    2014-01-01

    We compared the diagnostic accuracy of the Carba NP test with that of a straightforward matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) method for detecting carbapenemase-producing Enterobacteriaceae (CPE). Using PCR as the reference method, both tests demonstrated a sensitivity of 87% and a specificity of 100%. MALDI-TOF MS offers a potential alternative for the rapid detection of CPE in the clinical laboratory setting. PMID:25187633

  14. Identification of Neisseria gonorrhoeae by the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry System Is Improved by a Database Extension.

    PubMed

    Schweitzer, Valentijn A; van Dam, Alje P; Hananta, I Putu Yuda; Schuurman, Rob; Kusters, Johannes G; Rentenaar, Rob J

    2016-04-01

    Identification ofNeisseria gonorrhoeaeby the Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system may be affected by "B consistency categorization." A supplementary database of 17N. gonorrhoeaemain spectra was constructed. Twelve of 64N. gonorrhoeaeidentifications were categorized with B consistency, which disappeared using the supplementary database. Database extension did not result in misidentification ofNeisseria meningitidis. PMID:26763972

  15. Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Differentiation of the Dimorphic Fungal Species Paracoccidioides brasiliensis and Paracoccidioides lutzii

    PubMed Central

    Del Negro, Gilda M. B.; Grenfell, Rafaella C.; Vidal, Monica S. M.; Thomaz, Danilo Y.; de Figueiredo, Dulce S. Y.; Bagagli, Eduardo; Juliano, Luiz; Benard, Gil

    2015-01-01

    Isolates of Paracoccidioides brasiliensis and Paracoccidioides lutzii, previously characterized by molecular techniques, were identified for the first time by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). All isolates were correctly identified, with log score values of >2.0. Thus, MALDI-TOF MS is a new tool for differentiating species of the genus Paracoccidioides. PMID:25631803

  16. Influence of Culture Media on Detection of Carbapenem Hydrolysis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Ramos, Ana Carolina; Carvalhaes, Cecília Godoy; Cordeiro-Moura, Jhonatha Rodrigo; Rockstroh, Anna Carolina; Machado, Antonia Maria Oliveira; Gales, Ana Cristina

    2016-07-01

    In this study, we evaluated the influence of distinct bacterial growth media on detection of carbapenemase hydrolysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. False-negative results were observed for OXA-25-, OXA-26-, and OXA-72-producing Acinetobacter baumannii isolates grown on MacConkey agar medium. The other culture media showed 100% sensitivity and 100% specificity for detecting carbapenemase. PMID:27076665

  17. A Simple and Safe Protocol for Preparing Brucella Samples for Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Analysis

    PubMed Central

    Mesureur, Jennifer; Ranaldi, Sébastien; Monnin, Valérie; Girard, Victoria; Arend, Sandrine; Welker, Martin; O'Callaghan, David

    2015-01-01

    We describe a simple protocol to inactivate the biosafety level 3 (BSL3) pathogens Brucella prior to their analysis by matrix-assisted laser desorption ionization–time of flight mass spectrometry. This method is also effective for several other bacterial pathogens and allows storage, and eventually shipping, of inactivated samples; therefore, it might be routinely applied to unidentified bacteria, for the safety of laboratory workers. PMID:26582837

  18. Does the Capsule Interfere with Performance of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Cryptococcus neoformans and Cryptococcus gattii?

    PubMed Central

    Grenfell, Rafaella C.; Vidal, Monica S. M.; Giudice, Mauro C.; Del Negro, Gilda M. B.; Juliano, Luiz; Benard, Gil; de Almeida Júnior, João N.

    2015-01-01

    We described the impact of the capsule size for Cryptococcus neoformans and Cryptococcus gattii identification at the species level by Bruker matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). After experimental capsule size modulation, we observed that reducing the capsule size resulted in improved identification by Bruker MALDI-TOF MS across all of the reference strains analyzed. PMID:26659203

  19. Identification of Non-diphtheriae Corynebacterium by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Alatoom, Adnan A.; Cazanave, Charles J.; Cunningham, Scott A.; Ihde, Sherry M.

    2012-01-01

    We evaluated the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for identification of 92 clinical isolates of Corynebacterium species in comparison to identification using rpoB or 16S rRNA gene sequencing. Eighty isolates (87%) yielded a score of ≥1.700, and all of these were correctly identified to the species level with the exception of Corynebacterium aurimucosum being misidentified as the closely related Corynebacterium minutissimum. PMID:22075579

  20. Identification of non-diphtheriae corynebacterium by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Alatoom, Adnan A; Cazanave, Charles J; Cunningham, Scott A; Ihde, Sherry M; Patel, Robin

    2012-01-01

    We evaluated the Bruker Biotyper matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for identification of 92 clinical isolates of Corynebacterium species in comparison to identification using rpoB or 16S rRNA gene sequencing. Eighty isolates (87%) yielded a score of ≥1.700, and all of these were correctly identified to the species level with the exception of Corynebacterium aurimucosum being misidentified as the closely related Corynebacterium minutissimum. PMID:22075579

  1. Identification of Clinically Relevant Corynebacterium spp., Arcanobacterium haemolyticum, and Rhodococcus equi by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Juiz, Pedro; Salas, Carlos; Almela, Manel; de la Fuente, Celia García; Zboromyrska, Yuliya; Navas, Jesús; Bosch, Jordi; Agüero, Jesús; de la Bellacasa, Jorge Puig; Martínez-Martínez, Luis

    2012-01-01

    The identification of 83 Corynebacterium, 13 Arcanobacterium haemolyticum, and 10 Rhodococcus equi strains by conventional methods (API Coryne complemented with 16S rRNA gene sequence analysis) was compared with matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry identification. The correlation between API and MALDI-TOF results was 89%. MALDI-TOF is a rapid and accurate system for identification of the above-mentioned microorganisms. PMID:22337985

  2. Does the Capsule Interfere with Performance of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Cryptococcus neoformans and Cryptococcus gattii?

    PubMed

    Thomaz, Danilo Y; Grenfell, Rafaella C; Vidal, Monica S M; Giudice, Mauro C; Del Negro, Gilda M B; Juliano, Luiz; Benard, Gil; de Almeida Júnior, João N

    2016-02-01

    We described the impact of the capsule size for Cryptococcus neoformans and Cryptococcus gattii identification at the species level by Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). After experimental capsule size modulation, we observed that reducing the capsule size resulted in improved identification by Bruker MALDI-TOF MS across all of the reference strains analyzed. PMID:26659203

  3. Combined Atomic Force Microscope-Based Topographical Imaging and Nanometer Scale Resolved Proximal Probe Thermal Desorption/Electrospray Ionization-Mass Spectrometry

    SciTech Connect

    Ovchinnikova, Olga S; Nikiforov, Maxim; Bradshaw, James A; Jesse, Stephen; Van Berkel, Gary J

    2011-01-01

    Nanometer scale proximal probe thermal desorption/electrospray ionization mass spectrometry (TD/ESI-MS) was demonstrated for molecular surface sampling of caffeine from a thin film using a 30 nm diameter nano-thermal analysis (nano-TA) probe tip in an atomic force microscope (AFM) coupled via a vapor transfer line and ESI interface to a MS detection platform. Using a probe temperature of 350 C and a spot sampling time of 30 s, conical desorption craters 250 nm in diameter and 100 nm deep were created as shown through subsequent topographical imaging of the surface within the same system. Automated sampling of a 5 x 2 array of spots, with 2 m spacing between spots, and real time selective detection of the desorbed caffeine using tandem mass spectrometry was also demonstrated. Estimated from the crater volume (~2x106 nm3), only about 10 amol (2 fg) of caffeine was liberated from each thermal desorption crater in the thin film. These results illustrate a relatively simple experimental setup and means to acquire in automated fashion sub-micrometer scale spatial sampling resolution and mass spectral detection of materials amenable to TD. The ability to achieve MS-based chemical imaging with 250 nm scale spatial resolution with this system is anticipated.

  4. Identification of Weissella species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    PubMed Central

    Lee, Meng-Rui; Tsai, Chia-Jung; Teng, Shih-Hua; Hsueh, Po-Ren

    2015-01-01

    Although some Weissella species play beneficial roles in food fermentation and in probiotic products, others such as Weissella confusa are emerging Gram-positive pathogens in immunocompromised hosts. Weissella species are difficult to identify by conventional biochemical methods and commercial automated systems and are easily misidentified as Lactobacillus and Leuconostoc species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly being used for bacterial identification. Little, however, is known about the effectiveness of MALDI-TOF MS in identifying clinical isolates of Weissella to the species level. In this study, we evaluated whether the MALDI-TOF MS Bruker Biotyper system could accurately identify a total of 20 W. confusa and 2 W. cibaria blood isolates that had been confirmed by 16s rRNA sequencing analysis. The MALDI-TOF Biotyper system yielded no reliable identification results based on the current reference spectra for the two species (all score values <1.7). New W. confusa spectra were created by randomly selecting 3 W. confusa isolates and external validation was performed by testing the remaining 17 W. confusa isolates using the new spectra. The new main spectra projection (MSP) yielded reliable score values of >2 for all isolates with the exception of one (score value, 1.963). Our results showed that the MSPs in the current database are not sufficient for correctly identifying W. confusa or W. cibaria. Further studies including more Weissella isolates are warranted to further validate the performance of MALDI-TOF in identifying Weissella species. PMID:26594208

  5. Using Surface-Assisted Laser Desorption/Ionization Mass Spectrometry to Detect ss- and ds-Oligodeoxynucleotides

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Tsen; Huang, Ming-Feng; Chang, Huan-Tsung

    2013-06-01

    We applied surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) with HgTe nanostructures as the matrix for the detection of single- and double-stranded oligodeoxynucleotides (ss-ODNs and ds-ODNs). The concentrations of surfactant and additives (metal ions, an amine) and the pH and ionic strength of the sample matrix played significantly different roles in the detection of ss- and ds-ODNs with various sequences. In the presence of Brij 76 (1.5 %), Hg2+ (7.5 μM), and cadaverine (10 μM) at pH 5.0, this SALDI-MS approach allowed the simultaneous detection of T15, T20, T33, and T40, with limits of detection at the femtomole-to-picomole level and sample-to-sample intensity variation <23 %. In the presence of Ag+ (1 μM) and cadaverine (10 μM) at pH 7.0, this technique allowed the detection of randomly sequenced ss- and ds-ODNs at concentrations down to the femtomole level. To the best of our knowledge, this paper is the first to report the detection of ss-ODNs (up to 50-mer) and ds-ODNs (up to 30 base pairs) through the combination of SALDI-MS with HgTe nanostructures as matrices. We demonstrated the practicality of this approach through analysis of a single nucleotide polymorphism that determines the fate of the valine residue in the β-globin of sickle cell megaloblasts.

  6. Distinctive Glycerophospholipid Profiles of Human Seminoma and Adjacent Normal Tissues by Desorption Electrospray Ionization Imaging Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Masterson, Timothy A.; Dill, Allison L.; Eberlin, Livia S.; Mattarozzi, Monica; Cheng, Liang; Beck, Stephen D. W.; Bianchi, Federica; Cooks, R. Graham

    2011-08-01

    Desorption electrospray ionization mass spectrometry (DESI-MS) has been successfully used to discriminate between normal and cancerous human tissue from different anatomical sites. On the basis of this, DESI-MS imaging was used to characterize human seminoma and adjacent normal tissue. Seminoma and adjacent normal paired human tissue sections (40 tissues) from 15 patients undergoing radical orchiectomy were flash frozen in liquid nitrogen and sectioned to 15 μm thickness and thaw mounted to glass slides. The entire sample was two-dimensionally analyzed by the charged solvent spray to form a molecular image of the biological tissue. DESI-MS images were compared with formalin-fixed, hematoxylin and eosin (H&E) stained slides of the same material. Increased signal intensity was detected for two seminolipids [seminolipid (16:0/16:0) and seminolipid (30:0)] in the normal tubule testis tissue; these compounds were undetectable in seminoma tissue, as well as from the surrounding fat, muscle, and blood vessels. A glycerophosphoinositol [PI(18:0/20:4)] was also found at increased intensity in the normal testes tubule tissue when compared with seminoma tissue. Ascorbic acid (i.e., vitamin C) was found at increased amounts in seminoma tissue when compared with normal tissue. DESI-MS analysis was successfully used to visualize the location of several types of molecules across human seminoma and normal tissues. Discrimination between seminoma and adjacent normal testes tubules was achieved on the basis of the spatial distributions and varying intensities of particular lipid species as well as ascorbic acid. The increased presence of ascorbic acid within seminoma compared with normal seminiferous tubules was previously unknown.

  7. Differentiation of Microbial Species and Strains in Coculture Biofilms by Multivariate Analysis of Laser Desorption Postionization Mass Spectra

    SciTech Connect

    University of Illinois at Chicago; Montana State University; Bhardwaj, Chhavi; Cui, Yang; Hofstetter, Theresa; Liu, Suet Yi; Bernstein, Hans C.; Carlson, Ross P.; Ahmed, Musahid; Hanley, Luke

    2013-04-01

    7.87 to 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze biofilms comprised of binary cultures of interacting microorganisms. The effect of photon energy was examined using both tunable synchrotron and laser sources of VUV radiation. Principal components analysis (PCA) was applied to the MS data to differentiate species in Escherichia coli-Saccharomyces cerevisiae coculture biofilms. PCA of LDPI-MS also differentiated individual E. coli strains in a biofilm comprised of two interacting gene deletion strains, even though these strains differed from the wild type K-12 strain by no more than four gene deletions each out of approximately 2000 genes. PCA treatment of 7.87 eV LDPI-MS data separated the E. coli strains into three distinct groups two ?pure? groups and a mixed region. Furthermore, the ?pure? regions of the E. coli cocultures showed greater variance by PCA when analyzed by 7.87 eV photon energies than by 10.5 eV radiation. Comparison of the 7.87 and 10.5 eV data is consistent with the expectation that the lower photon energy selects a subset of low ionization energy analytes while 10.5 eV is more inclusive, detecting a wider range of analytes. These two VUV photon energies therefore give different spreads via PCA and their respective use in LDPI-MS constitute an additional experimental parameter to differentiate strains and species.

  8. Accurate mass fragment library for rapid analysis of pesticides on produce using ambient pressure desorption ionization with high-resolution mass spectrometry.

    PubMed

    Kern, Sara E; Lin, Lora A; Fricke, Frederick L

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]⁺) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]⁺ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]⁺ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli

  9. Accurate Mass Fragment Library for Rapid Analysis of Pesticides on Produce Using Ambient Pressure Desorption Ionization with High-Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Kern, Sara E.; Lin, Lora A.; Fricke, Frederick L.

    2014-08-01

    U.S. food imports have been increasing steadily for decades, intensifying the need for a rapid and sensitive screening technique. A method has been developed that uses foam disks to sample the surface of incoming produce. This work provides complimentary information to the extensive amount of published pesticide fragmentation data collected using LCMS systems (Sack et al. Journal of Agricultural and Food Chemistry, 59, 6383-6411, 2011; Mol et al. Analytical and Bioanalytical Chemistry, 403, 2891-2908, 2012). The disks are directly analyzed using transmission-mode direct analysis in real time (DART) ambient pressure desorption ionization coupled to a high resolution accurate mass-mass spectrometer (HRAM-MS). In order to provide more certainty in the identification of the pesticides detected, a library of accurate mass fragments and isotopes of the protonated parent molecular ion (the [M+H]+) has been developed. The HRAM-MS is equipped with a quadrupole mass filter, providing the capability of "data-dependent" fragmentation, as opposed to "all -ion" fragmentation (where all of the ions enter a collision chamber and are fragmented at once). A temperature gradient for the DART helium stream and multiple collision energies were employed to detect and fragment 164 pesticides of varying chemical classes, sizes, and polarities. The accurate mass information of precursor ([M+H]+ ion) and fragment ions is essential in correctly identifying chemical contaminants on the surface of imported produce. Additionally, the inclusion of isotopes of the [M+H]+ in the database adds another metric to the confirmation process. The fragmentation data were collected using a Q-Exactive mass spectrometer and were added to a database used to process data collected with an Exactive mass spectrometer, an instrument that is more readily available for this screening application. The commodities investigated range from smooth-skinned produce such as apples to rougher surfaces like broccoli. The

  10. Three-Dimensional Imaging of Lipids and Metabolites in Tissues by Nanospray Desorption Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Cha, Jeeyeon; Dey, Sudhansu K.; yang, Pengxiang; Prieto, Mari; Laskin, Julia

    2015-03-01

    Abstract Three-dimensional (3D) imaging of tissue sections is a new frontier in mass spectrometry imaging (MSI). Here we report on fast 3D imaging of lipids and metabolites associated with mouse uterine decidual cells and embryo at the implantation site on day 6 of pregnancy. 2D imaging of 16-20 serial tissue sections deposited on the same glass slide was performed using nanospray desorption electrospray ionization (nano-DESI) – an ambient ionization technique that enables sensitive localized analysis of analytes on surfaces without special sample pre-treatment. In this proof-of-principle study, nano-DESI was coupled to a high-resolution Q-Exactive instrument operated at high repetition rate of >5 Hz with moderate mass resolution of 35,000 (m/Δm at m/z 200), which enabled acquisition of the entire 3D image with a spatial resolution of ~150 μm in less than 4.5 hours. The results demonstrate localization of acetylcholine in the primary decidual zone (PDZ) of the implantation site throughout the depth of the tissue examined, indicating an important role of this signaling molecule in decidualization. Choline and phosphocholine – metabolites associated with cell growth – are enhanced in the PDZ and abundant in other cellular regions of the implantation site. Very different 3D distributions were obtained for fatty acids (FA), oleic acid and linoleic acid (FA 18:1 and FA 18:2), differing only by one double bond. Localization of FA 18:2 in the PDZ indicates its important role in decidualization while FA 18:1 is distributed more evenly throughout the tissue. In contrast, several lysophosphatidylcholines (LPC) observed in this study show donut-like distributions with localization around the PDZ. Complementary distributions with minimal overlap were observed for LPC 18:0 and FA 18:2 while the 3D image of the potential precursor phosphatidylcholine (PC 36:2) showed a significant overlap with both LPC 18:0 and FA 18:2.

  11. Identification of Arcanobacterium pluranimalium by matrix-assisted laser desorption ionization-time of flight mass spectrometry and, as novel target, by sequencing pluranimaliumlysin encoding gene pla.

    PubMed

    Balbutskaya, A; Sammra, O; Nagib, S; Hijazin, M; Alber, J; Lämmler, C; Foster, G; Erhard, M; Wragg, P N; Abdulmawjood, A; Prenger-Berninghoff, E

    2014-01-31

    In the present study 13 Arcanobacterium pluranimalium strains isolated from various animal origin could successfully be identified phenotypically by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and genotypically by sequencing 16S rDNA and the pluranimaliumlysin encoding gene pla. The detection of mass spectra by MALDI-TOF MS and the novel genotypic approach using gene pla might help to identify A. pluranimalium in future and might elucidate the role this species plays in infections of animals. PMID:24345409

  12. In Situ Probing of Cholesterol in Astrocytes at the Single Cell Level using Laser Desorption Ionization Mass Spectrometric Imaging with Colloidal Silver

    SciTech Connect

    Perdian, D.C.; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S.; Yeung, Edward S.; and Lee, Young Jin

    2010-03-18

    Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level.

  13. Identification of arsenobetaine in sole, lemon sole, flounder, dab, crab and shrimps by field desorption and fast atom bombardment mass spectrometry

    SciTech Connect

    Luten, J.B.; Riekwel-Booy, G.; Greef, M.C.; de Brauw, I.N.

    1983-01-01

    Organo-arsenic has been isolated from sole, lemon sole, flounder, dab, crab and shrimps by extraction or ion-exchange in combination with thin-layer chromatography. An alkaline digestion of the samples, followed by a reduction with sodiumborohydride leads to the formation of trimethylarsine. Field desorption mass spectrometry (FDMS) can be used to identify arsenobetaine in the isolates. Sufficient purification by thin-layer chromatography is found to be a prerequisite for the detection of a protonated molecular ion of arsenobetaine. If this situation is not met acid enchanced FDMS or Fast Atom Bombardment mass spectrometry in high resolution can be used successfully.

  14. A novel type of matrix for surface-assisted laser desorption-ionization mass spectrometric detection of biomolecules using metal-organic frameworks.

    PubMed

    Fu, Chien-Ping; Lirio, Stephen; Liu, Wan-Ling; Lin, Chia-Her; Huang, Hsi-Ya

    2015-08-12

    A 3D metal-organic framework (MOF) nanomaterial as matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and tandem mass spectrometry (MS/MS) was developed for the analysis of complex biomolecules. Unlike other nanoparticle matrices, this MOF nanomaterial does not need chemical modification prior to use. An exceptional signal reproducibility as well as very low background interferences in analyzing mono-/di-saccharides, peptides and complex starch digests demonstrate its high potential for biomolecule assays, especially for small molecules. PMID:26320964

  15. A technique for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble aromatic polyamides.

    PubMed

    Gies, Anthony P; Nonidez, William K

    2004-04-01

    Wet grinding methods for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble low molecular mass oligomers (<4600 Da) of Nomex and Kevlar are described. Optimum conditions for sample preparation are given along with a detailed analysis of the spectra obtained. Two matrix materials were employed in this analysis, 1,8-dihydroxyanthrone (dithranol) and 3-aminoquinoline with potassium trifluoroacetate used as the cationizing agent. The spectra obtained in this study are sensitive to the matrix, molar mixing ratios of matrix/polymer/cationizing agent, and the sample preparation method. PMID:15053662

  16. Detailed investigation on the possibility of nanoparticles of various metal elements for surface-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Yonezawa, Tetsu; Kawasaki, Hideya; Tarui, Akira; Watanabe, Takehiro; Arakawa, Ryuichi; Shimada, Toshihiro; Mafuné, Fumitaka

    2009-03-01

    In this paper, we describe systematic detailed considerations of the feasibility of using various metal nanoparticles for organic-matrix-free surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). In order to avoid the influence of organic molecules on the nanoparticles, stabilizer-free bare nanoparticles of Ag, Au, Cu and Pt were prepared by laser ablation. Although all metal nanoparticles absorbed N(2) laser light (337 nm) energy, the performance of desorption/ionization of a representative peptide, angiotensin I, strongly depended on the metal element. Citrate buffer was used as a proton source; it reduced the amount of alkali cation adducts present. Then, protonated molecules of analytes predominated in the mass spectra when Au and Pt nanoparticles were used. Pt nanoparticles showed the highest performance in SALDI-MS, owing to their smaller heat conductivity and higher melting temperature. The selective desorption of a cationic surfactant with longer alkyl chains and a peptide with methionine was also observed. PMID:19276588

  17. Experimental investigations of the internal energy of molecules evaporated via laser-induced acoustic desorption into a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Shea, Ryan C; Petzold, Christopher J; Liu, Ji-Ang; Kenttämaa, Hilkka I

    2007-03-01

    The internal energy of neutral gas-phase organic and biomolecules, evaporated by means of laser-induced acoustic desorption (LIAD) into a Fourier transform ion cyclotron resonance mass spectrometer, was investigated through several experimental approaches. The desorbed molecules were demonstrated not to undergo degradation during the desorption process by collecting LIAD-evaporated molecules and subjecting them to analysis by electrospray ionization/quadrupole ion trap mass spectrometry. Previously established gas-phase basicity values were remeasured for LIAD-evaporated organic molecules and biomolecules with the use of the bracketing method. No endothermic reactions were observed. The remeasured basicity values are in close agreement with the values reported in the literature. The amount of internal energy deposited during LIAD is concluded to be less than a few kilocalories per mole. Chemical ionization with a series of proton-transfer reagents was employed to obtain a breakdown curve for a protonated dipeptide, Val-Pro, evaporated by LIAD. Comparison of this breakdown curve with a previously published analogous curve obtained by using substrate-assisted laser desorption (SALD) to evaporate the peptide suggests that the molecules evaporated via LIAD have a similar internal energy as those evaporated via SALD. PMID:17263513

  18. In situ identification of organic components of ink used in books from the 1900s by atmospheric pressure matrix assisted laser desorption ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Giurato, Laura; Candura, Andrea; Grasso, Giuseppe; Spoto, Giuseppe

    2009-11-01

    This paper describes the use of atmospheric pressure/matrix assisted laser desorption ionization-mass spectrometry (AP/MALDI-MS) as a spatially resolved analytical technique for the study of organic components of inks used to print coloured parts of ancient books. The possibility to operate at atmospheric pressure makes MALDI-MS a new in situ micro-destructive diagnostic tool suitable for analysing samples in air, simplifying the investigation of the organic components of artistic and archaeological objects. In this work, several organic dyes and pigments were identified in situ by analysing different coloured areas of books printed in the years 1911 and 1920. The detected colouring materials, which were available since the 1890s, were often identified as a mixture, confirming the typical procedures used in the lithographic printing processes. The matrix deposition and the laser desorption process did not cause visible alteration of the sample surface.

  19. Determination of seven pyrethroids biocides and their synergist in indoor air by thermal-desorption gas chromatography/mass spectrometry after sampling on Tenax TA ® passive tubes.

    PubMed

    Raeppel, Caroline; Appenzeller, Brice M; Millet, Maurice

    2015-01-01

    A method coupling thermal desorption and gas chromatography/mass spectrometry (GC/MS) was developed for the simultaneous determination of 7 pyrethroids (allethrin, bifenthrin, cyphenothrin, imiprothrin, permethrin, prallethrin and tetramethrin) and piperonyl butoxide adsorbed on Tenax TA(®) passive samplers after exposure in indoor air. Thermal desorption was selected as it permits efficient and rapid extraction without solvent used together with a good sensitivity. Detection (S/N>3) and quantification (S/N>10) limits varied between 0.001 ng and 2.5 ng and between 0.005 and 10 ng respectively with a reproducibility varied between 14% (bifenthrin) and 39% (permethrin). The method was used for the comparison indoor air contamination after low-pressure spraying and fumigation application in a rubbish chute situated in the basement of a building. PMID:25281107

  20. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    PubMed

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully. PMID:23455645

  1. New design for a time-of-flight mass spectrometer with a liquid beam laser desorption ion source for the analysis of biomolecules

    NASA Astrophysics Data System (ADS)

    Charvat, A.; Lugovoj, E.; Faubel, M.; Abel, B.

    2004-05-01

    We describe a novel liquid beam mass spectrometer, based on a recently discovered nanosecond laser desorption phenomenon, [W. Kleinekofort, J. Avdiev, and B. Brutschy, Int. J. Mass Ion. Processes 152, 135 (1996)] which allows the liquid-to-vacuum transfer, and subsequent mass analysis of pre-existing ions and ionic associates from liquid microjets of aqueous solutions. The goal of our novel technical approach is to establish a system with good mass resolution that implements improvements on critical components that make the system more reliable and easier to operate. For laser desorption pulsed dye-laser difference frequency mixing is used that provides tunable infrared light near the absorption maximum of liquid water around 3 μm. Different types of liquid beam glass nozzles (convergent capillary and aperture plate nozzles) are investigated and characterized. Starting from theoretical considerations of hydrodynamic drag forces on micrometer size droplets in supersonic rarefied gas flows we succeeded in capturing efficiently the liquid beam in a liquid beam recycling trap operating at the vapor pressure of liquid water. For improving the pollution resistance, the liquid jet high vacuum ion source region is spatially separated from the reflectron time-of-flight mass spectrometer (TOF-MS) working behind a gate valve in an ultrahigh vacuum environment. A simple (simulation optimized) ion optics is employed for the ion transfer from the source to the high vacuum region. This new feature is also mostly responsible for the improved mass resolution. With the present tandem-TOF-MS setup a resolution of m/Δm≈1800 for the low and m/Δm≈700 in the high mass region has been obtained for several biomolecules of different mass and complexity (amino acids, insulin, and cytochrome c).

  2. Ultra high vacuum high precision low background setup with temperature control for thermal desorption mass spectroscopy (TDA-MS) of hydrogen in metals.

    PubMed

    Merzlikin, Sergiy V; Borodin, S; Vogel, D; Rohwerder, M

    2015-05-01

    In this work, a newly developed UHV-based high precision low background setup for hydrogen thermal desorption analysis (TDA) of metallic samples is presented. Using an infrared heating with a low thermal capacity enables a precise control of the temperature and rapid cool down of the measurement chamber. This novel TDA-set up is superior in sensitivity to almost every standard hydrogen analyzer available commercially due to the special design of the measurement chamber, resulting in a very low hydrogen background. No effects of background drift characteristic as for carrier gas based TDA instruments were observed, ensuring linearity and reproducibility of the analysis. This setup will prove to be valuable for detailed investigations of hydrogen trapping sites in steels and other alloys. With a determined limit of detection of 5.9×10(-3)µg g(-1) hydrogen the developed instrument is able to determine extremely low hydrogen amounts even at very low hydrogen desorption rates. This work clearly demonstrates the great potential of ultra-high vacuum thermal desorption mass spectroscopy instrumentation. PMID:25702992

  3. Performance evaluation of a thermal desorption/gas chromatographic/mass spectrometric method for the characterization of waste tank headspace samples

    SciTech Connect

    Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Bayne, C.K.; Jenkins, R.A.

    1997-03-01

    A thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS) method was validated for the determination of volatile organic compounds collected on carbonaceous triple sorbent traps and applied to characterize samples of headspace gases collected from underground nuclear waste storage tanks at the U.S. Department of Energy`s Hanford site, in Richland, WA. Method validation used vapor-phase standards generated from 25 target analytes, including alkanes, alkyl alcohols, alkyl ketones, alkylated aromatics, and alkyl nitriles. The target analytes represent a group of compounds identified in one of the most problematic tanks. TD/GC/MS was carried out with modified injectors. Performance was characterized based on desorption efficiency, reproducibility, stability, and linearity of the calibration, method detection limits, preanalytical holding time, and quality control limits for surrogate standard recoveries. Desorption efficiencies were all greater than 82%, and the majority of the analytes (23 out of 25) had reproducibility values less than 24% near the method detection levels. The method was applied to the analysis of a total of 305 samples collected from the headspaces of 48 underground waste storge tanks. Quality control procedures were implemented to monitor sampling and TD/GC/MS method. 33 refs., 2 figs., 4 tabs.

  4. Online laser desorption-multiphoton postionization mass spectrometry of individual aerosol particles: molecular source indicators for particles emitted from different traffic-related and wood combustion sources.

    PubMed

    Bente, Matthias; Sklorz, Martin; Streibel, Thorsten; Zimmermann, Ralf

    2008-12-01

    Direct inlet aerosol mass spectrometry plays an increasingly important role in applied and fundamental aerosol and nanoparticle research. Laser desorption/ionization (LDI) based techniques for single particle time-of-flight mass spectrometry (LDI-SP-TOFMS) are a promising approach in the chemical analysis of single aerosol particles, especially for the detection of inorganic species and distinction of particle classes. However, until now the detection of molecular organic compounds on a single particle basis has been difficult due to the high laser power densities which are required for the LDI process as well as due to the inherent matrix effects associated with this ionization technique. By the application of a two-step approach, where an IR desorption laser pulse is applied to perform a gentle desorption of organic material from the single particle surface and a second UV-laser performs the soft ionization of the desorbed species, this drawback of laser based single particles mass spectrometry can be overcome. The postionization of the desorbed molecules has been accomplished in this work by resonance enhanced multiphoton ionization (REMPI) using a KrF excimer laser (248 nm). REMPI allows an almost fragmentation free trace analysis of polycyclic aromatic hydrocarbons (PAHs) and their derivatives from individual single particles (laser desorption-REMPI postionization-single particle-time-of-flight mass spectrometry or LD-REMPI-SP-TOFMS). Crucial system parameters of the home-built aerosol mass spectrometer such as the power densities and the relative timing of both lasers were optimized with respect to the detectability of particle source specific organic signatures using well characterized standard particles. In a second step, the LD-REMPI-SP-TOFMS system was applied to analyze different real world aerosols (spruce wood combustion, gasoline car exhaust, beech wood combustion, and diesel car exhaust). It was possible to distinguish the particles from different

  5. Design and Characterization of a High-power Laser-induced Acoustic Desorption (LIAD) Probe Coupled with a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Shea, Ryan C.; Habicht, Steven C.; Vaughn, Weldon E.; Kenttämaa, Hilkka I.

    2008-01-01

    We report here the construction and characterization of a high-power laser-induced acoustic desorption (LIAD) probe designed for Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometers to facilitate analysis of non-volatile, thermally labile compounds. This “next generation” LIAD probe offers significant improvements in sensitivity and desorption efficiency for analytes with larger molecular weights via the use of higher laser irradiances. Unlike the previous probes which utilized a power limiting optical fiber to transmit the laser pulses through the probe, this probe employs a set of mirrors and a focusing lens. At the end of the probe, the energy from the laser pulses propagates through a thin metal foil as an acoustic wave, resulting in desorption of neutral molecules from the opposite side of the foil. Following desorption, the molecules can be ionized by electron impact or chemical ionization. Almost an order of magnitude greater power density (up to 5.0 × 109 W/cm2) is achievable on the backside of the foil with the high-power LIAD probe compared to the earlier LIAD probes (maximum power density ~9.0 × 108 W/cm2). The use of higher laser irradiances is demonstrated not to cause fragmentation of the analyte. The use of higher laser irradiances increases sensitivity since it results in the evaporation of a greater number of molecules per laser pulse. Measurement of the average velocities of LIAD evaporated molecules demonstrates that higher laser irradiances do not correlate with higher velocities of the gaseous analyte molecules. PMID:17319645

  6. Antimicrobial activities and matrix-assisted laser desorption/ionization mass spectrometry of Bacillus isolates from the marine sponge Aplysina aerophoba.

    PubMed

    Pabel, Christian T; Vater, Joachim; Wilde, Christopher; Franke, Peter; Hofemeister, Jürgen; Adler, Barbara; Bringmann, Gerhard; Hacker, Jörg; Hentschel, Ute

    2003-01-01

    The aim of this study was to isolate bacteria that are resistant to the strong antimicrobial metabolites characteristic of Aplysina aerophoba. For this purpose, bacterial isolation was performed on agar plates to which sponge tissue extract had been added. Following screening for antifungal and antimicrobial activities, 5 strains were chosen for more detailed analyses. 16S ribosomal DNA sequencing revealed that all isolates belonged to the genus Bacillus, specifically B. subtilis and B. pumilus. Using a combination of matrix-assisted laser desorption/ ionization mass spectrometry typing of whole cells and antimicrobial bioassays against selected reference strains, the bioactive metabolites were identified as lipopeptides. PMID:14730425

  7. Laser desorption/ionization time-of-flight mass spectrometry: A predictive tool for the lifetime of organic light emitting devices

    SciTech Connect

    Scholz, Sebastian; Meerheim, Rico; Luessem, Bjoern; Leo, Karl

    2009-01-26

    For improving the lifetime of organic light emitting devices (OLEDs), the analysis of the chemical degradation requires a deep understanding of the involved reaction pathways. We show that the dissociation reactions of phosphorescent emitters and the additional complexations with the used surrounding blocking layers are the dominant intrinsic degradation mechanisms in long living p-i-n type OLEDs. We use the laser desorption/ionization (LDI) time-of-flight mass spectrometry to correlate the laser-induced ion formation with the observed lifetime of the organic devices. The superlinear correlation between the LDI forced reactions and the lifetimes allows the prediction of the lifetime of an OLED with new materials.

  8. On-Tissue Derivatization via Electrospray Deposition for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Endogenous Fatty Acids in Rat Brain Tissues.

    PubMed

    Wu, Qian; Comi, Troy J; Li, Bin; Rubakhin, Stanislav S; Sweedler, Jonathan V

    2016-06-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is used for the multiplex detection and characterization of diverse analytes over a wide mass range directly from tissues. However, analyte coverage with MALDI MSI is typically limited to the more abundant compounds, which have m/z values that are distinct from MALDI matrix-related ions. On-tissue analyte derivatization addresses these issues by selectively tagging functional groups specific to a class of analytes, while simultaneously changing their molecular masses and improving their desorption and ionization efficiency. We evaluated electrospray deposition of liquid-phase derivatization agents as a means of on-tissue analyte derivatization using 2-picolylamine; we were able to detect a range of endogenous fatty acids with MALDI MSI. When compared with airbrush application, electrospray led to a 3-fold improvement in detection limits and decreased analyte delocalization. Six fatty acids were detected and visualized from rat cerebrum tissue using a MALDI MSI instrument operating in positive mode. MALDI MSI of the hippocampal area allowed targeted fatty acid analysis of the dentate gyrus granule cell layer and the CA1 pyramidal layer with a 20-μm pixel width, without degrading the localization of other lipids during liquid-phase analyte derivatization. PMID:27181709

  9. Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) of low molecular weight organic compounds and synthetic polymers using zinc oxide (ZnO) nanoparticles.

    PubMed

    Watanabe, Takehiro; Kawasaki, Hideya; Yonezawa, Tetsu; Arakawa, Ryuichi

    2008-08-01

    We have developed surface-assisted laser desorption/ionization mass spectrometry using zinc oxide (ZnO) nanoparticles with anisotropic shapes (ZnO-SALDI-MS). The mass spectra showed low background noises in the low m/z, i.e. less than 500 u region. Thus, we succeeded in SALDI ionization on low molecular weight organic compounds, such as verapamil hydrochloride, testosterone, and polypropylene glycol (PPG) (average molecular weight 400) without using a liquid matrix or buffers such as citric acids. In addition, we found that ZnO-SALDI has advantages in post-source decay (PSD) analysis and produced a simple mass spectrum for phospholipids. The ZnO-SALDI spectra for synthetic polymers of polyethylene glycol (PEG), polystyrene (PS) and polymethylmethacrylate (PMMA) showed the sensitivity and molecular weight distribution to be comparable to matrix-assisted laser desorption/ionization (MALDI) spectra with a 2,5-dihydroxybenzoic acid (DHB) matrix. ZnO-SALDI shows good performance for synthetic polymers as well as low molecular weight organic compounds. PMID:18286665

  10. Detection of gaseous compounds by needle trap sampling and direct thermal-desorption photoionization mass spectrometry: concept and demonstrative application to breath gas analysis.

    PubMed

    Kleeblatt, Juliane; Schubert, Jochen K; Zimmermann, Ralf

    2015-02-01

    A fast detection method to analyze gaseous organic compounds in complex gas mixtures was developed, using a needle trap device (NTD) in conjunction with thermal-desorption photoionization time-of-flight mass spectrometry (TD-PI-TOFMS). The mass spectrometer was coupled via a deactivated fused silica capillary to an injector of a gas chromatograph. In the hot injector, the analytes collected on the NTD were thermally desorbed and directly transferred to the PI-TOFMS ion source. The molecules are softly ionized either by single photon ionization (SPI, 118 nm) or by resonance enhanced multiphoton ionization (REMPI, 266 nm), and the molecular ion signals are detected in the TOF mass analyzer. Analyte desorption and the subsequent PI-TOFMS detection step only lasts ten seconds. The specific selectivity of REMPI (i.e., aromatic compounds) and universal ionization characteristics render PI-MS as a promising detection system. As a first demonstrative application, the alveolar phase breath gas of healthy, nonsmoking subjects was sampled on NTDs. While smaller organic compounds such as acetone, acetaldehyde, isoprene, or cysteamine can be detected in the breath gas with SPI, REMPI depicts the aromatic substances phenol and indole at 266 nm. In the breath gas of a healthy, smoking male subject, several xenobiotic substances such as benzene, toluene, styrene, and ethylbenzene can be found as well. Furthermore, the NTD-REMPI-TOFMS setup was tested for breath gas taken from a mechanically ventilated pig under continuous intravenous propofol (2,6-diisopropylphenol, narcotic drug) infusion. PMID:25517186

  11. On-Tissue Derivatization via Electrospray Deposition for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Endogenous Fatty Acids in Rat Brain Tissues

    PubMed Central

    2016-01-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is used for the multiplex detection and characterization of diverse analytes over a wide mass range directly from tissues. However, analyte coverage with MALDI MSI is typically limited to the more abundant compounds, which have m/z values that are distinct from MALDI matrix-related ions. On-tissue analyte derivatization addresses these issues by selectively tagging functional groups specific to a class of analytes, while simultaneously changing their molecular masses and improving their desorption and ionization efficiency. We evaluated electrospray deposition of liquid-phase derivatization agents as a means of on-tissue analyte derivatization using 2-picolylamine; we were able to detect a range of endogenous fatty acids with MALDI MSI. When compared with airbrush application, electrospray led to a 3-fold improvement in detection limits and decreased analyte delocalization. Six fatty acids were detected and visualized from rat cerebrum tissue using a MALDI MSI instrument operating in positive mode. MALDI MSI of the hippocampal area allowed targeted fatty acid analysis of the dentate gyrus granule cell layer and the CA1 pyramidal layer with a 20-μm pixel width, without degrading the localization of other lipids during liquid-phase analyte derivatization. PMID:27181709

  12. Effect of delay time and grid voltage changes on the average molecular mass of polydisperse polymers and polymeric blends determined by delayed extraction matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Mineo, Placido; Vitalini, Daniele; Scamporrino, Emilio; Bazzano, Sebastiano; Alicata, Rossana

    2005-01-01

    The dependence of the calculated average molecular mass of a polyethylene glycol with a large polydispersity on the instrumental parameters adopted in the acquisition of mass spectra using delayed extraction matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (DE MALDI-TOFMS) was investigated. It has been shown that a combined effect of delay times and potential gradients can act on the ion cloud in the source chamber affecting both mass resolution and average molecular mass value of the analyzed polymeric sample. Also examined was a blend of two different polymers (a PEG and a PMMA commercial sample having a similar average molecular mass), which presents an additional problem concerning the discrimination among the different polymer species as a function of the experimental conditions. In this work, the best instrumental conditions to obtain both good resolution and a correct average molecular mass for the examined polydisperse sample are reported. PMID:16134231

  13. Signal enhancement in electrospray laser desorption/ionization mass spectrometry by using a black oxide-coated metal target and a relatively low laser fluence.

    PubMed

    Kononikhin, Alexey; Huang, Min-Zong; Popov, Igor; Kostyukevich, Yury; Kukaev, Evgeny; Boldyrev, Alexey; Spasskiy, Alexander; Leypunskiy, Ilya; Shiea, Jentaie; Nikolaev, Eugene

    2013-01-01

    The electrospray Laser desorption/ionization (ELDI) method is actively used for direct sample analysis and ambient mass spectrometry imaging. The optimizing of Laser desorption conditions is essential for this technology. In this work, we propose using a metal target with a black oxide (Fe3O4) coating to increase the signal in ELDI-MS for peptides and small proteins. The experiments were performed on an LTQ-FT mass spectrometer equipped with a home-made ELDI ion source. A cutter blade with black oxide coating was used as a target. A nitrogen laser was used with the following parameters: 337 nm, pulse duration 4ns, repetition rate 10 Hz, fluence to approximately 700 Jm(-2). More than a five times signal increase was observed for a substance P peptide when a coated and a non-coated metal target were compared. No ion signal was observed for proteins if the same fluence and the standard stainless steel target were used. With the assistance of the Fe3O4 coated metal target and a relatively low laser fluence < or =700 Jm(-2)), proteins such as insulin, ubiquitin and myoglobin were successfully ionized. It was demonstrated that the Fe3O4-coated metal target can be used efficiently to assist laser desorption and thus significantly increase the analyte signal in ELDI-MS. A relatively low laser fluence (< or = 700 Jm(-2)) was enough to desorb peptides and proteins (up to 17 kDal with the assistance of the Fe3O4-coated metal target under ambient conditions. PMID:24575623

  14. Fatal Nocardia farcinica Bacteremia Diagnosed by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry in a Patient with Myelodysplastic Syndrome Treated with Corticosteroids

    PubMed Central

    Moretti, Amedeo; Guercini, Francesco; Cardaccia, Angela; Furbetta, Leone; Agnelli, Giancarlo; Bistoni, Francesco; Mencacci, Antonella

    2013-01-01

    Nocardia farcinica is a Gram-positive weakly acid-fast filamentous saprophytic bacterium, an uncommon cause of human infections, acquired usually through the respiratory tract, often life-threatening, and associated with different clinical presentations. Predisposing conditions for N. farcinica infections include hematologic malignancies, treatment with corticosteroids, and any other condition of immunosuppression. Clinical and microbiological diagnoses of N. farcinica infections are troublesome, and the isolation and identification of the etiologic agent are difficult and time-consuming processes. We describe a case of fatal disseminated infection in a patient with myelodysplastic syndrome, treated with corticosteroids, in which N. farcinica has been isolated from blood culture and identified by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry. The patient died after 18 days of hospitalization in spite of triple antimicrobial therapy. Nocardia farcinica infection should be suspected in patients with history of malignancy, under corticosteroid therapy, suffering from subacute pulmonary infection,and who do not respond to conventional antimicrobial therapy. Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry can be a valuable tool for rapid diagnosis of nocardiosis. PMID:23690786

  15. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) coupled to XAD fractionation: Method to algal organic matter characterization.

    PubMed

    Nicolau, Rudy; Leloup, Maud; Lachassagne, Delphine; Pinault, Emilie; Feuillade-Cathalifaud, Geneviève

    2015-05-01

    This work is focused on the development of an analytical procedure for the improvement of the Organic Matter structure characterization, particularly the algal matter. Two fractions of algal organic matter from laboratory cultures of algae (Euglena gracilis) and cyanobacteria (Microcystis aeruginosa) were extracted with XAD resins. The fractions were studied using laser desorption ionization (LDI) and Matrix-Assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). A comparison with the natural organic matter characteristics from commercial humic acids and fulvic acids extracted from Suwannee River was performed. Results show that algal and natural organic matters have unique quasi-polymeric structures. Significant repeating patterns were identified. Different fractions extracted from organic matter with common origin had common structures. Thus, 44, 114 and 169Da peaks separation for fractions from E. gracilis organic matter and 28, 58 and 100Da for M. aeruginosa ones were clearly observed. Using the developed protocol, a structural scheme and organic matter composition were obtained. The range 600-2000Da contained more architectural composition differences than the range 100-600Da, suggesting that organic matter is composed of an assembly of common small molecules. Associated to specific monomers, particular patterns were common to all samples but assembly and resulting structure were unique for each organic matter. Thus, XAD fractionation coupled to mass spectroscopy allowed determining a specific fingerprint for each organic matter. PMID:25702991

  16. Effects of matrix structure/acidity on ion formation in matrix-assisted laser desorption ionization mass spectrometry

    SciTech Connect

    Gimon-Kinsel, M.; Preston-Schaffter, L.M.; Kinsel, G.R.; Russell, D.H.

    1997-03-12

    The involvement of ground and excited state proton transfer reactions in matrix-assisted laser desorption ionization (MALDI) of bradykinin and bovine insulin is examined using a series of p-substituted aniline compounds as matrices. Semiempirical calculations of ground and excited state acidity of the p-substituted aniline and anilinium ions are presented. A linear correlation between log (analyte [A + H]{sup +} ion yield) and matrix acidity is obtained. The behavior of the seven p-substituted anilines is discussed in terms of the relationship between matrix compound structure, reactivity, and ability to act as a MALDI matrix. 44 refs., 4 figs., 5 tabs.

  17. Inkjet-Printed Gold Nanoparticle Surfaces for the Detection of Low Molecular Weight Biomolecules by Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Marsico, Alyssa L. M.; Creran, Brian; Duncan, Bradley; Elci, S. Gokhan; Jiang, Ying; Onasch, Timothy B.; Wormhoudt, Joda; Rotello, Vincent M.; Vachet, Richard W.

    2015-11-01

    Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity.

  18. Determination of trichloroanisole and trichlorophenol in wineries' ambient air by passive sampling and thermal desorption-gas chromatography coupled to tandem mass spectrometry.

    PubMed

    Camino-Sánchez, F J; Bermúdez-Peinado, R; Zafra-Gómez, A; Ruíz-García, J; Vílchez-Quero, J L

    2015-02-01

    The present paper describes the calibration of selected passive samplers used in the quantitation of trichlorophenol and trichloroanisole in wineries' ambient air, by calculating the corresponding sampling rates. The method is based on passive sampling with sorbent tubes and involves thermal desorption-gas chromatography-triple quadrupole mass spectrometry analysis. Three commercially available sorbents were tested using sampling cartridges with a radial design instead of axial ones. The best results were found for Tenax TA™. Sampling rates (R-values) for the selected sorbents were determined. Passive sampling was also used for accurately determining the amount of compounds present in the air. Adequate correlation coefficients between the mass of the target analytes and exposure time were obtained. The proposed validated method is a useful tool for the early detection of trichloroanisole and its precursor trichlorophenol in wineries' ambient air while avoiding contamination of wine or winery facilities. PMID:25576042

  19. Detection of in-situ derivatized peptides in microbial biofilms by laser desorption 7.87 eV postionizaton mass spectrometry.

    SciTech Connect

    Edirisinghe, P. D.; Moore, J. F.; Skinner-Nemec, K. A.; Lindberg, C.; Giometti, C. S.; Veryovkin, I. V.; Hunt, J. E.; Pellin, M. J.; Hanley, L.; Biosciences Division; Univ. of Illinois at Chicago; MassThink

    2007-01-01

    A novel analytical method based on laser desorption postionization mass spectrometry (LDPI-MS) was developed to investigate the competence and sporulation factor-a pentapeptide of amino acid sequence ERGMT-within intact Bacillus subtilis biofilms. Derivatization of the neat ERGMT peptide with quinoline- and anthracene-based tags was separately used to lower the peptide ionization potential and permit direct ionization by 7.87-eV vacuum ultraviolet radiation. The techniques of mass shifting and selective ionization of the derivatized peptide were combined here to permit detection of ERGMT peptide within intact biofilms by LDPI-MS, without any prior extraction or chromatographic separation. Finally, imaging MS specific to the derivatized peptide was demonstrated on an intact biofilm using LDPI-MS. The presence of ERGMT in the biofilms was verified by bulk extraction/LC-MS. However, MALDI imaging MS analyses were unable to detect ERGMT within intact biofilms.

  20. Desorption electrospray ionization mass spectrometry analysis of lipids after two-dimensional high-performance thin-layer chromatography partial separation

    PubMed Central

    Paglia, Giuseppe; Ifa, Demian R.; Wu, Chunping; Corso, Gaetano; Cooks, R. Graham

    2010-01-01

    Molecular imaging of separate but still incompletely resolved spots on high-performance thin-layer chromatography (HPTLC) plates is used for the direct analysis of porcine brain lipids by desorption electrospray ionization mass spectrometry (DESI-MS). Seven class-specific spots were imaged in the negative ion mode and shown to contain more than fifty lipids. A low lateral resolution of 400 × 400 μm allowed simple, rapid and incomplete separation to be combined with DESI imaging for the identification of many components of these extremely complex mixtures. In this work, tandem mass spectrometry (MS/MS) was also employed to confirm the identity of particular lipids directly on HPTLC plates. PMID:20128616

  1. Inkjet-printed gold nanoparticle surfaces for the detection of low molecular weight biomolecules by laser desorption/ionization mass spectrometry.

    PubMed

    Marsico, Alyssa L M; Creran, Brian; Duncan, Bradley; Elci, S Gokhan; Jiang, Ying; Onasch, Timothy B; Wormhoudt, Joda; Rotello, Vincent M; Vachet, Richard W

    2015-11-01

    Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstract ᅟ. PMID:26202457

  2. A high resolving power multiple reflection matrix-assisted laser desorption/ionization time-of-flight mass spectrometer.

    PubMed

    Piyadasa, C K; Håkansson, P; Ariyaratne, T R

    1999-01-01

    Two electrostatic mirrors, mounted symmetrically on the same optical axis facing each other, are used to increase the time-of-flight of molecular ions produced in matrix-assisted laser desorption/ionization (MALDI). The mirrors, which are used in the non-compensating mode, are located between a MALDI ion source and a stop detector. The source is operated at 10.5 kV acceleration voltage using the delayed extraction technique. The high voltage for the mirror arrangement is switched on after the desorption event when the molecular ions have drifted into the region between the mirrors. The ions are trapped by successive reflections of the opposite electrostatic fields in the mirrors until the electric fields are switched off. The number of reflections depends on the speed of the ions when they enter the mirror trap and the ontime of the mirrors. When the electric fields are removed during the motion of the ions towards the stop detector, the ions penetrate the grids of the mirror and reach that detector. The extension of the flight path due to the number of reflections is used to increase the resolving power in time-of-flight spectra. Values of 55,000 for substance-P (MW 1346.7) and 31,000 for bovine insulin (MW 5734) were obtained for single laser shot spectra. PMID:10230069

  3. System and method of infrared matrix-assisted laser desorption/ionization mass spectrometry in polyacrylamide gels

    DOEpatents

    Haglund, Jr., Richard F.; Ermer, David R.; Baltz-Knorr, Michelle Lee

    2004-11-30

    A system and method for desorption and ionization of analytes in an ablation medium. In one embodiment, the method includes the steps of preparing a sample having analytes in a medium including at least one component, freezing the sample at a sufficiently low temperature so that at least part of the sample has a phase transition, and irradiating the frozen sample with short-pulse radiation to cause medium ablation and desorption and ionization of the analytes. The method further includes the steps of selecting a resonant vibrational mode of at least one component of the medium and selecting an energy source tuned to emit radiation substantially at the wavelength of the selected resonant vibrational mode. The medium is an electrophoresis medium having polyacrylamide. In one embodiment, the energy source is a laser, where the laser can be a free electron laser tunable to generate short-pulse radiation. Alternatively, the laser can be a solid state laser tunable to generate short-pulse radiation. The laser can emit light at various ranges of wavelength.

  4. Depth profiling of inks in authentic and counterfeit banknotes by electrospray laser desorption ionization/mass spectrometry.

    PubMed

    Kao, Yi-Ying; Cheng, Sy-Chyi; Cheng, Chu-Nian; Shiea, Jentaie

    2016-01-01

    Electrospray laser desorption ionization is an ambient ionization technique that generates neutrals via laser desorption and ionizes those neutrals in an electrospray plume and was utilized to characterize inks in different layers of copy paper and banknotes of various currencies. Depth profiling of inks was performed on overlapping color bands on copy paper by repeatedly scanning the line with a pulsed laser beam operated at a fixed energy. The molecules in the ink on a banknote were desorbed by irradiating the banknote surface with a laser beam operated at different energies, with results indicating that different ions were detected at different depths. The analysis of authentic $US100, $100 RMB and $1000 NTD banknotes indicated that ions detected in 'color-shifting' and 'typography' regions were significantly different. Additionally, the abundances of some ions dramatically changed with the depth of the aforementioned regions. This approach was used to distinguish authentic $1000 NTD banknotes from counterfeits. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26757068

  5. Rapid Genus- and Species-Specific Identification of Cronobacter spp. by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry▿

    PubMed Central

    Stephan, Roger; Ziegler, Dominik; Pflüger, Valentin; Vogel, Guido; Lehner, Angelika

    2010-01-01

    Cronobacter spp. are Gram-negative opportunistic food-borne pathogens and are known as rare but important causes of life-threatening neonatal infections. Rapid and reliable identification of Cronobacter species and their differentiation from phenotypically similar, nonpathogenic Enterobacter turicensis, Enterobacter helveticus, and Enterobacter pulveris have become increasingly important. We evaluated here the application of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for rapid genus and species identification of the six Cronobacter species recognized so far. To this end, we developed a reference MS database library that includes 54 Cronobacter target strains as well as 17 nontarget strains. The strains provided reproducible and unique mass spectra profiles covering a wide molecular mass range (2,000 to 30,000 Da). Genus- and species-specific biomarker protein mass patterns were determined. The defined biomarker mass patterns (Spectral Archive and Microbial Identification System [SARAMIS] SuperSpectrum) were validated using 36 strains from various Cronobacter species as well as eight nontarget strains. For all strains the mass spectrometry-based identification scheme yielded identical results as with a PCR-based identification system. All strains were correctly identified, and no nontarget strain was misidentified as Cronobacter. Our study demonstrates that MALDI-TOF MS is a reliable and powerful tool for the rapid identification of Cronobacter strains to the genus and species level. PMID:20554814

  6. Direct matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of lysozyme contained in hen egg white.

    PubMed

    Smolira, Anna; Hałas, Stanisław

    2016-01-01

    As a natural antibacterial peptide, lysozyme (LZ) is widely used in medicine and the food industry. Despite many years of research on this compound, its new antibacterial properties are still to be determined. The primary aim of this work is to demonstrate the application of the matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometric analysis of LZ directly in hen egg white samples without extraction thereof. The egg white samples were kept over 10 weeks at room temperature and measured every week. The resulting positive and negative ion mass spectra were then compared to determine the intensity of the LZ mass peak. Storage of the egg white for over 10 weeks did not influence the LZ mass peak intensity (both positive and negative). It can be concluded that the LZ concentration in the egg white samples did not vary with time. The effect of the matrix/sample ratio on LZ detection was also examined, and it was found to be different in the case of positive and negative ionization. The mass peaks of LZ oligomeric forms were observed in all mass spectra, so the MALDI method could be used in subsequent studies. PMID:26863071

  7. Analysis of Antiretrovirals in Single Hair Strands for Evaluation of Drug Adherence with Infrared-Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging.

    PubMed

    Rosen, Elias P; Thompson, Corbin G; Bokhart, Mark T; Prince, Heather M A; Sykes, Craig; Muddiman, David C; Kashuba, Angela D M

    2016-01-19

    Adherence to a drug regimen can be a strong predictor of health outcomes, and validated measures of adherence are necessary at all stages of therapy from drug development to prescription. Many of the existing metrics of drug adherence (e.g., self-report, pill counts, blood monitoring) have limitations, and analysis of hair strands has recently emerged as an objective alternative. Traditional methods of hair analysis based on LC-MS/MS (segmenting strands at ≥1 cm length) are not capable of preserving a temporal record of drug intake at higher resolution than approximately 1 month. Here, we evaluated the detectability of HIV antiretrovirals (ARVs) in hair from a range of drug classes using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) with 100 μm resolution. Infrared laser desorption of hair strands was shown to penetrate into the strand cortex, allowing direct measurement by MSI without analyte extraction. Using optimized desorption conditions, a linear correlation between IR-MALDESI ion abundance and LC-MS/MS response was observed for six common ARVs with estimated limits of detection less than or equal to 1.6 ng/mg hair. The distribution of efavirenz (EFV) was then monitored in a series of hair strands collected from HIV infected, virologically suppressed patients. Because of the role hair melanin plays in accumulation of basic drugs (like most ARVs), an MSI method to quantify the melanin biomarker pyrrole-2,3,5-tricarboxylic acid (PTCA) was evaluated as a means of normalizing drug response between patients to develop broadly applicable adherence criteria. PMID:26688545

  8. Development of stir-bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry for the analysis of musks in vegetables and amended soils.

    PubMed

    Aguirre, Josu; Bizkarguenaga, Ekhiñe; Iparraguirre, Arantza; Fernández, Luis Ángel; Zuloaga, Olatz; Prieto, Ailette

    2014-02-17

    The aim of this study was to develop a sensitive and environment-friendly method based on stir-bar sorptive extraction (SBSE) followed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) to determine 8 synthetic musks (musk ambrette, musk ketone, celestolide, tonalide, galaxolide, phantolide, traseolide, and cashmeran) in vegetables (lettuce, carrot, and pepper) and amended soil samples. In a first step sorptive extraction was studied both in the headspace (HSSE) and in the immerse mode (SBSE). The best results were obtained in the immersion mode which was further studied. The influence of the main factors: methanol (20%) and NaCl addition (0%), extraction temperature (40°C) and time (180 min), extraction solvent volume (9 mL) and stirring rate (600 rpm) on the efficiency of SBSE was evaluated by means of experimental designs. In the case of TD, desorption time (10 min), desorption temperature (300°C), cryo-focusing temperature (-30°C), vent flow (75 mL/min) and vent pressure (7.2 psi) were studied using both a fractioned factorial design and a central composite design (CCD). The method was validated in terms of apparent recoveries (AR%), method detection limits (MDLs) and precision at two different concentration levels. Although quantification using instrumental calibration rendered odd results in most of the cases, satisfactory recoveries (74-126%) were obtained in the case of matrix-matched calibration approach for all of the analytes and matrices studied at the two concentration levels evaluated. MDLs in the range of 0.01-0.8 ng/g and 0.01-1.1 ng/g were obtained for vegetables and amended soil samples, respectively. RSD values within 1-23% were obtained for all the analytes and matrices. Finally, the method was applied to the determination of musks in vegetable and amended soil samples. PMID:24491767

  9. Determination of five booster biocides in seawater by stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.

    PubMed

    Giráldez, I; Chaguaceda, E; Bujalance, M; Morales, E

    2013-01-01

    Stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) have been optimized for the determination of five organic booster biocides (Chlorothalonil, Dichlofluanid, Sea-Nine 211, Irgarol 1051 and TCMTB) in seawater samples. The parameters affecting the desorption and absorption steps were investigated using 10 mL seawater samples. The optimised conditions consisted of an addition of 0.2 g mL(-1) KCl to the sample, which was extracted with 10mm length, 0.5mm film thickness stir bars coated with polydimethylsiloxane (PDMS), and stirred at 900 rpm for 90 min at room temperature (25 °C) in a vial. Desorption was carried out at 280 °C for 5 min under 50 mL min(-1) of helium flow in the splitless mode while maintaining a cryotrapping temperature of 20 °C in the programmed-temperature vaporization (PTV) injector of the GC-MS system. Finally, the PTV injector was ramped to a temperature of 280 °C and the analytes were separated in the GC and detected by MS using the selected-ion monitoring (SIM) mode. The detection limits of booster biocides were found to be in the range of 0.005-0.9 μg L(-1). The regression coefficients were higher than 0.999 for all analytes. The average recovery was higher than 72% (R.S.D.: 7-15%). All these figures of merit were established running samples in triplicate. This simple, accurate, sensitive and selective analytical method may be used for the determination of trace amounts of booster biocides in water samples from marinas. PMID:23246091

  10. Nanoparticle-assisted laser desorption/ionization using sinapic acid-modified iron oxide nanoparticles for mass spectrometry analysis.

    PubMed

    Komori, Hanaka; Hashizaki, Riho; Osaka, Issey; Hibi, Takao; Katano, Hajime; Taira, Shu

    2015-12-21

    Iron oxide-based nanoparticles (NP) were covalently modified with sinapic acid (SA) through a condensation reaction to assist the ionization of both large and small molecules. The morphology of SA-modified NPs (SA-NP) was characterized by transmission electron microscopy (TEM), and the modification of the NP surface with SA was confirmed using ultraviolet (UV) and infrared (IR) spectroscopy. The number of SA molecules was estimated to be 6 per NP. SA-NP-assisted laser desorption/ionization was carried out on small molecules, such as pesticides and plant hormones, and large molecules, such as peptides and proteins. A peptide fragment from degraded proteins was detected more efficiently compared with conventional methods. PMID:26535417

  11. Nanostructured diamond-like carbon on digital versatile disc as a matrix-free target for laser desorption/ionization mass spectrometry.

    PubMed

    Najam-ul-Haq, Muhammad; Rainer, Matthias; Huck, Christian W; Hausberger, Peter; Kraushaar, Harald; Bonn, Günther K

    2008-10-01

    A nanostructured diamond-like carbon (DLC) coated digital versatile disk (DVD) target is presented as a matrix-free sample support for application in laser desorption/ionization mass spectrometry (LDI-MS). A large number of vacancies, defects, relative sp(2) carbon content, and nanogrooves of DLC films support the LDI phenomenon. The observed absorptivity of DLC is in the range of 305-330 nm (nitrogen laser, 337 nm). The universal applicability is demonstrated through different analytes like amino acids, carbohydrates, lipids, peptides, and other metabolites. Carbohydrates and amino acids are analyzed as sodium and potassium adducts. Peptides are detectable in their protonated forms, which avoid the extra need of additives for ionization. A bovine serum albumin (BSA) digest is analyzed to demonstrate the performance for peptide mixtures, coupled with the material-enhanced laser desorption/ionization (MELDI) approach. The detection limit of the described matrix-free target is investigated to be 10 fmol/microL for [Glu(1)]-fibrinopeptide B (m/z 1570.6) and 1 fmol/microL for L-sorbose (Na(+) adduct). The device does not require any chemical functionalization in contrast to other matrix-free systems. The inertness of DLC provides longer lifetimes without any deterioration in the detection sensitivity. Broad applicability allows high performance analysis in metabolomics and peptidomics. Furthermore the DLC coated DVD (1.4 GB) sample support is used as a storage device for measured and processed data together with sampling on a single device. PMID:18729472

  12. Using electrospray-assisted laser desorption/ionization mass spectrometry to characterize organic compounds separated on thin-layer chromatography plates.

    PubMed

    Lin, Shu-Yao; Huang, Min-Zong; Chang, Hui-Chiu; Shiea, Jentaie

    2007-11-15

    Electrospray-assisted laser desorption/ionization (ELDI), an ionization method that combines laser desorption and electrospray ionization (ESI), can be used under ambient conditions to characterize organic compounds (including FD&C dyes, amines, extracts of a drug tablet) separated in the central track on a thin-layer chromatography (TLC) plate coated with either reversed-phase C18 particles or normal-phase silica gel. After drying, the TLC plate was placed on an acrylic sample holder set in front of the sampling skimmer of an ion trap mass analyzer. The chemicals at the center of the TLC plate were analyzed by pushing the sample holder into the path of a laser beam with a syringe pump. The molecules in the sample spot were desorbed by continuously irradiating the surface of the TLC plate with a pulsed nitrogen laser. Then, the desorbed sample molecules entered an ESI plume where they were ionized through the reactions with the charged species (including protons, hydronium ions and their cluster ions, solvent ions, and charged droplets) generated by electrospraying a methanol/water solution. MS/MS analyses were also performed to further characterize the analytes. The detection limit of TLC/ELDI/MS is approximately 10(-6) M. This was evaluated by using FD&C red dye as the standard. A linear relationship was found for the calibration curve with the concentration of FD&C red dye ranged from 10(-3) to 10(-6) M. PMID:17929897

  13. Application of an automatic thermal desorption-gas chromatography-mass spectrometry system for the analysis of polycyclic aromatic hydrocarbons in airborne particulate matter.

    PubMed

    Gil-Moltó, J; Varea, M; Galindo, N; Crespo, J

    2009-02-27

    The application of the thermal desorption (TD) method coupled with gas chromatography-mass spectrometry (GC-MS) to the analysis of aerosol organics has been the focus of many studies in recent years. This technique overcomes the main drawbacks of the solvent extraction approach such as the use of large amounts of toxic organic solvents and long and laborious extraction processes. In this work, the application of an automatic TD-GC-MS instrument for the determination of particle-bound polycyclic aromatic hydrocarbons (PAHs) is evaluated. This device offers the advantage of allowing the analysis of either gaseous or particulate organics without any modification. Once the thermal desorption conditions for PAH extraction were optimised, the method was verified on NIST standard reference material (SRM) 1649a urban dust, showing good linearity, reproducibility and accuracy for all target PAHs. The method has been applied to PM10 and PM2.5 samples collected on quartz fibre filters with low volume samplers, demonstrating its capability to quantify PAHs when only a small amount of sample is available. PMID:19150718

  14. Model verification of thermal programmed desorption-mass spectrometry for estimation of release energy values for polycyclic aromatic hydrocarbons on mineral sorbents.

    PubMed

    Nicholl, Sara I; Talley, Jeffrey W; Silliman, Stephan

    2004-11-01

    The physical availability of organic compounds in soil and sediment strongly influences their bioavailability and toxicity. Previous work has indicated that physical availability changes throughout the processes of aging and treatment and that it can be linked to the energy required to release the compound from its sorbent matrix, with a higher energy indicating a more tightly bound compound. This study focused on determining release energy values for various mineral geosorbents (glass beads, sand, and kaolin) contaminated with a 16 polycyclic aromatic hydrocarbon (PAH) mixture. The sorbents were analyzed using thermal program desorption/mass spectrometry (TPD/MS) and the release energy values were calculated from the resulting thermograms utilizing a nonlinear fit of the analytical solution to a simplified version of the Polanyi-Wigner equation. This solution method resulted in a series of combinations of values for the pre-exponential factor (v) and release energy (E) that produced desorption rate curves with similar errors when fit to actual data sets. These combinations can be viewed as an error surface, which clearly shows a valley of minimum error values spanning the range of both E and v. This indicates that this method may not provide a unique set of E- and v-values and suggests that the simplified version of the Polanyi-Wigner equation cannot be used to determine release energy based on TPD data alone. PMID:15559267

  15. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (GALDI-FTICR-MS)

    SciTech Connect

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; J. Michelle Kotler; Jill R. Scott

    2008-10-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) has been employed to determine how effectively bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO-2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition ofC18H39O7Na-. Anatural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination were estimated to be 3 parts per trillion or~7 zeptomoles (10-21) per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTICR-MS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  16. Direct Imaging Mass Spectrometry of Plant Leaves Using Surface-assisted Laser Desorption/Ionization with Sputter-deposited Platinum Film.

    PubMed

    Ozawa, Tomoyuki; Osaka, Issey; Hamada, Satoshi; Murakami, Tatsuya; Miyazato, Akio; Kawasaki, Hideya; Arakawa, Ryuichi

    2016-01-01

    Plant leaves administered with systemic insecticides as agricultural chemicals were analyzed using imaging mass spectrometry (IMS). Matrix-assisted laser desorption/ionization (MALDI) is inadequate for the detection of insecticides on leaves because of the charge-up effect that occurs on the non-conductive surface of the leaves. In this study, surface-assisted laser desorption/ionization with a sputter-deposited platinum film (Pt-SALDI) was used for direct analysis of chemicals in plant leaves. Sputter-deposited platinum (Pt) films were prepared on leaves administered with the insecticides. A sputter-deposited Pt film with porous structure was used as the matrix for Pt-SALDI. Acephate and acetamiprid contained in the insecticides on the leaves could be detected using Pt-SALDI-MS, but these chemical components could not be adequately detected using MALDI-MS because of the charge-up effect. Enhancement of ion yields for the insecticides was achieved using Pt-SALDI, accompanied by prevention of the charge-up effect by the conductive Pt film. The movement of systemic insecticides in plants could be observed clearly using Pt-SALDI-IMS. The distribution and movement of components of systemic insecticides on leaves could be analyzed directly using Pt-SALDI-IMS. Additionally, changes in the properties of the chemicals with time, as an indicator of the permeability of the insecticides, could be evaluated. PMID:27169661

  17. Optimization of a Dynamic Headspace-Thermal Desorption-Gas Chromatography/Mass Spectrometry procedure for the determination of furfurals in vinegars.

    PubMed

    Manzini, Simona; Durante, Caterina; Baschieri, Carlo; Cocchi, Marina; Sighinolfi, Simona; Totaro, Sara; Marchetti, Andrea

    2011-08-15

    The use of a Dynamic Headspace System (DHS) device combined with a Thermal Desorption Unit (TDU) interfaced to a Gas Chromatography/Mass Spectrometry (GC/MS) system is proposed for the determination of furfurals in oenological products. An experimental design protocol has been employed for the optimization of the instrumental settings concerning DHS and TDU extraction and desorption steps. It has been possible to individuate the following optimized conditions: incubation temperature 40°C, purge volume 800 mL, dry volume 1500 mL, TDU hold time 5 min and incubation time 10 min. The performance of two different SPE sorbents, namely Tenax TA and Tenax GR used for the furfurals trapping, was investigated too. The developed DHS sampling procedure showed good reproducibility values with a RSD% lower than 10% for all the monitored species. The optimized experimental settings have been used to determine furfurals in several vinegar samples obtained by traditional procedure starting from cooked grape musts, i.e. in Aceto Balsamico Tradizionale di Modena (ABTM). In fact, the control of these species is extremely important for quality and safety issues. PMID:21726711

  18. Facile synthesis of gold@graphitized mesoporous silica nanocomposite and its surface-assisted laser desorption/ionization for time-of-flight mass spectroscopy.

    PubMed

    Xu, Guiju; Liu, Shengju; Peng, Jiaxi; Lv, Wenping; Wu, Ren'an

    2015-01-28

    In this work, a novel core-shell structured gold@graphitized mesoporous silica nanocomposite (Au@GMSN) was synthesized by in situ graphitization of template within the mesochannels of mesoporous silica shell on gold core and demonstrated to be promising nanomaterials for surface-assisted laser desorption/ionization time-of-flight mass spectroscopy (SALDI-TOF MS). The integration of the graphitized mesoporous silica with the gold nanoparticles endowed Au@GMSN with large surface areas of graphitic structure, good dispersibility, and strong ultraviolet (UV) absorption. Au@GMSN exerted the synergistic effect on the efficient detection of small-molecular-weight analytes including amino acids, neutral saccharides, peptides, and traditional Chinese medicine. The Au@GMSN-assisted laser desorption/ionization exhibited the following superiorities: high ionization efficiency, low fragmentation interference, favorable salt tolerance, and good reproducibility. Moreover, because of the large hydrophobic inner surface area of the graphitized mesoporous silica shell, the Au@GMSN demonstrated its promising capacity in the pre-enrichment of aromatic analytes prior to SALDI-TOF MS, which favored rapid and sensitive detection. PMID:25552293

  19. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis

    PubMed Central

    2010-01-01

    Background Successful defence of tobacco plants against attack from the oomycete Phytophthora nicotianae includes a type of local programmed cell death called the hypersensitive response. Complex and not completely understood signaling processes are required to mediate the development of this defence in the infected tissue. Here, we demonstrate that different families of metabolites can be monitored in small pieces of infected, mechanically-stressed, and healthy tobacco leaves using direct infrared laser desorption ionization orthogonal time-of-flight mass spectrometry. The defence response was monitored for 1 - 9 hours post infection. Results Infrared laser desorption ionization orthogonal time-of-flight mass spectrometry allows rapid and simultaneous detection in both negative and positive ion mode of a wide range of naturally occurring primary and secondary metabolites. An unsupervised principal component analysis was employed to identify correlations between changes in metabolite expression (obtained at different times and sample treatment conditions) and the overall defence response. A one-dimensional projection of the principal components 1 and 2 obtained from positive ion mode spectra was used to generate a Biological Response Index (BRI). The BRI obtained for each sample treatment was compared with the number of dead cells found in the respective tissue. The high correlation between these two values suggested that the BRI provides a rapid assessment of the plant response against the pathogen infection. Evaluation of the loading plots of the principal components (1 and 2) reveals a correlation among three metabolic cascades and the defence response generated in infected leaves. Analysis of selected phytohormones by liquid chromatography electrospray ionization mass spectrometry verified our findings. Conclusion The described methodology allows for rapid assessment of infection-specific changes in the plant metabolism, in particular of phenolics, alkaloids

  20. Interactions between sodium dodecyl sulfate micelles and peptides during matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of proteolytic digests.

    PubMed

    Tummala, Rama; Green-Church, Kari B; Limbach, Patrick A

    2005-09-01

    Although sodium dodecyl sulfate (SDS) is routinely used as a denaturing agent for proteins, its presence is highly detrimental on the analysis of peptides and proteins by mass spectrometry. It has been found, however, that when SDS is present in concentrations near to or above its critical micelle concentration (CMC), improvements in the matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of peptide mixtures or hydrophobic proteins are obtained. To elucidate possible explanations for such improvements, here we have undertaken a study examining the effect of SDS micelles on peptide mixtures. Fluorescently labeled peptides were used as probes to determine whether hydrophobic or hydrophilic peptides interact exclusively with SDS micelles. In addition, four globular proteins were digested with trypsin and then various amounts of SDS were added before MALDI mass spectrometry. To examine the role of mixture complexity on the mass spectral results, the tryptic digest of bovine serum albumin was also fractionated according to hydrophobicity before SDS treatment. Results from these experiments suggest that micelle-peptide interactions increase peptide-matrix cocrystallization irrespective of analyte hydrophobicity. As these studies were performed using the dried-droplet method of sample spotting, the presence of micelles is also hypothesized to reduce Marangoni effects during the crystallization process. PMID:16006141

  1. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assay for organophosphorus toxicants bound to human albumin at Tyr411.

    PubMed

    Li, Bin; Schopfer, Lawrence M; Hinrichs, Steven H; Masson, Patrick; Lockridge, Oksana

    2007-02-15

    Our goal was to determine whether chlorpyrifos oxon, dichlorvos, diisopropylfluorophosphate (DFP), and sarin covalently bind to human albumin. Human albumin or plasma was treated with organophosphorus (OP) agent at alkaline pH, digested with pepsin at pH 2.3, and analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Two singly charged peaks m/z 1718 and 1831, corresponding to the unlabeled peptide fragments containing the active site Tyr411 residue, were detected in all samples. The sequences of the two peptides were VRYTKKVPQVSTPTL and LVRYTKKVPQVSTPTL. The peptide-OP adducts of these peptides were also found. They had masses of 1854 and 1967 for chlorpyrifos oxon, 1825 and 1938 for dichlorvos, 1881 and 1994 for DFP, and 1838 and 1938 for sarin; these masses fit a mechanism whereby OP bound covalently to Tyr411. The binding of DFP to Tyr411 of human albumin was confirmed by electrospray tandem mass spectrometry and analysis of product ions. None of the OP-albumin adducts lost an alkoxy group, leading to the conclusion that aging did not occur. Our results show that OP pesticides and nerve agents bind covalently to human albumin at Tyr411. The presence of Tyr411 on an exposed surface of albumin suggests that an antibody response could be generated against OP-albumin adducts. PMID:17188226

  2. Enhanced Laser Desorption/Ionization Mass Spectrometric Detection of Gold Nanoparticles in Biological Samples Using the Synergy between Added Matrix and the Gold Core.

    PubMed

    Marsico, Alyssa L M; Elci, Gokhan S; Moyano, Daniel F; Yesilbag Tonga, Gulen; Duncan, Bradley; Landis, Ryan F; Rotello, Vincent M; Vachet, Richard W

    2015-12-15

    Laser desorption/ionization mass spectrometry (LDI-MS) has been used to detect gold nanoparticles (AuNPs) in biological samples, such as cells and tissues, by ionizing their attached monolayer ligands. Many NP-attached ligands, however, are difficult to ionize by LDI, making it impossible to track these NPs in biological samples. In this work, we demonstrate that concentrations of matrix-assisted LDI (MALDI) matrices an order of magnitude below the values typically used in MALDI can facilitate the selective detection of AuNPs with these ligands, even in samples as complex as cell lysate. This enhanced sensitivity arises from a synergistic relationship between the gold core and the matrix that helps to selectively ionize ligands attached to the AuNPs. PMID:26560844

  3. Metabolomic Analysis of Oxidative and Glycolytic Skeletal Muscles by Matrix-Assisted Laser Desorption/IonizationMass Spectrometric Imaging (MALDI MSI)

    NASA Astrophysics Data System (ADS)

    Tsai, Yu-Hsuan; Garrett, Timothy J.; Carter, Christy S.; Yost, Richard A.

    2015-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers that have different physiological, morphological, biochemical, and histological characteristics. In this work, skeletal muscles extensor digitorum longus, soleus, and whole gastrocnemius were analyzed by matrix-assisted laser desorption/ionization mass spectrometry to characterize small molecule metabolites of oxidative and glycolytic muscle fiber types as well as to visualize biomarker localization. Multivariate data analysis such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed to extract significant features. Different metabolic fingerprints were observed from oxidative and glycolytic fibers. Higher abundances of biomolecules such as antioxidant anserine as well as acylcarnitines were observed in the glycolytic fibers, whereas taurine and some nucleotides were found to be localized in the oxidative fibers.

  4. Optimisation of sorbent trapping and thermal desorption-gas chromatography-mass spectrometric conditions for sampling and analysis of hydrogen cyanide in air.

    PubMed

    Juillet, Yannick; Le Moullec, Sophie; Bégos, Arlette; Bellier, Bruno

    2005-06-01

    Among the chemicals belonging to the schedules of the Chemical Weapons Convention (CWC), sampling and analysis of highly volatile compounds such as hydrogen cyanide (HCN) require special consideration. The latter is present in numerous old chemical weapons that are stockpiled awaiting destruction in Northeastern France: thus, sampling on stockpile area and subsequent verification of HCN levels is compulsory to ensure safety of workers on these areas. The ability of several commercial sorbents to trap hydrogen cyanide at various concentration levels and in various humidity conditions, was evaluated. Furthermore, thermal desorption of the corresponding samples, followed by analysis by gas chromatography-mass spectrometry was also optimised. Carbosieve S-III, a molecular sieve possessing a very high specific area, proved the most efficient sorbent for HCN sampling in all conditions tested. Conversely, the presented results show that Tenax, albeit generally considered as the reference sorbent for air monitoring and analysis of CWC-related chemicals, is not suitable for HCN trapping. PMID:15912249

  5. Identification of oxidized methionine residues in peptides containing two methionine residues by derivatization and matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Hollemeyer, Klaus; Heinzle, Elmar; Tholey, Andreas

    2002-11-01

    Oxidation of methionine residues in peptides and proteins occurs in vivo or may be an artifact resulting from purification steps. We present a three step method for the localization of methionine sulfoxides in peptides with two methionine residues. In the first step, the N-terminus as well as other reactive side chain functions are blocked by acetylation. The resulting protected peptides are cleaved by cyanogen bromide. The cleavage does not occur at methionine sulfoxide but only at reduced methionine residues forming new amino termini. The newly formed amino group is then derivatized with a bromine containing compound in the last step of the procedure. The resulting peptide can easily be identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry using both the characteristic isotope pattern of the halogen and the metastable loss of methanesulfenic acid from oxidized residues. This procedure allows the unequivocal localization of oxidized methionines even in complex peptide mixtures. PMID:12442252

  6. Small-scale, high-throughput method for plant N-glycan preparation for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis.

    PubMed

    Matsuo, Kouki

    2011-06-15

    A simple, small-scale, and high-throughput method for preparation of plant N-glycans for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is described. This method entailed the extraction of soluble proteins, pepsin digestion, release of N-glycans by glycopeptidase A, and a three-step chromatographic purification process using cation exchange, anion exchange, and graphitized carbon. Homemade minicolumns using commercially available filter unit devices were used for N-glycan purification steps. All purification steps were designed to be easy. Using this method, N-glycans from 10-mg leaf samples of different plant species and only 2 μg of pure horseradish peroxidase were successfully purified. PMID:21320463

  7. Evaluation of Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Rapid Identification of Beta-Hemolytic Streptococci▿

    PubMed Central

    Cherkaoui, Abdessalam; Emonet, Stéphane; Fernandez, José; Schorderet, Didier; Schrenzel, Jacques

    2011-01-01

    This study was undertaken to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of beta-hemolytic streptococci. We compared Bruker Biotyper 2.0 with Vitek2 coupled to the agglutination test. MALDI-TOF MS analysis of 386 beta-hemolytic streptococcal isolates yielded high-confidence identification to the species level for all 386 isolates. The Vitek2 gave high-confidence identification to the species level for 88% of Streptococcus agalactiae isolates (n = 269/306), 92% of Streptococcus pyogenes isolates (n = 48/52), and 39% of isolates of Streptococcus dysgalactiae serogroups C and G (n = 11/28). PMID:21697322

  8. Desorption mass spectrometry: Revisiting the in-situ calibration technique for mixed group-V alloy MBE growth of ~3.3 μm diode lasers

    NASA Astrophysics Data System (ADS)

    Kaspi, Ron; Lu, Chunte; Yang, Chi; Newell, Timothy C.; Luong, Sanh

    2015-09-01

    We apply the desorption mass spectrometry (DMS) technique and analyze the desorbed Sb species in-situ during MBE growth of mixed As/Sb heterostructures. We demonstrate how DMS is useful in pre-growth calibration of the V/III ratio, the group-III ratio, as well as the Sb-content in quaternary or quinary mixed As/Sb alloys. We also apply DMS to the digital alloy growth method. For demonstration purposes, we start with an un-calibrated MBE system, use the DMS technique to calibrate all of the previously undetermined MBE parameters and grow a ~3.3 μm diode laser heterostructure in only one attempt. The results demonstrate that the DMS technique will allow the MBE to quickly converge toward a set of acceptable growth parameters without the need for ex-situ calibration of alloy composition.

  9. Metabolomic Analysis of Oxidative and Glycolytic Skeletal Muscles by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Imaging (MALDI MSI)

    PubMed Central

    Tsai, Yu-Hsuan; Garrett, Timothy J.; Carter, Christy S.; Yost, Richard A.

    2015-01-01

    Skeletal muscles are composed of heterogeneous muscle fibers that have different physiological, morphological, biochemical, and histological characteristics. In this work, skeletal muscles extensor digitorum longus, soleus, and whole gastrocnemius were analyzed by matrix-assisted laser desorption/ionization mass spectrometry to characterize small molecule metabolites of oxidative and glycolytic muscle fiber types as well as to visualize biomarker localization. Multivariate data analysis such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed to extract significant features. Different metabolic fingerprints were observed from oxidative and glycolytic fibers. Higher abundances of biomolecules such as antioxidant anserine as well as acylcarnitines were observed in the glycolytic fibers, whereas taurine and some nucleotides were found to be localized in the oxidative fibers. PMID:25893271

  10. Thermal transformation of bioactive caffeic acid on fumed silica seen by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods.

    PubMed

    Kulik, Tetiana V; Lipkovska, Natalia O; Barvinchenko, Valentyna M; Palyanytsya, Borys B; Kazakova, Olga A; Dudik, Olesia O; Menyhárd, Alfréd; László, Krisztina

    2016-05-15

    Thermochemical studies of hydroxycinnamic acid derivatives and their surface complexes are important for the pharmaceutical industry, medicine and for the development of technologies of heterogeneous biomass pyrolysis. In this study, structural and thermal transformations of caffeic acid complexes on silica surfaces were studied by UV-Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry (TPD MS) and quantum chemical methods. Two types of caffeic acid surface complexes are found to form through phenolic or carboxyl groups. The kinetic parameters of the chemical reactions of caffeic acid on silica surface are calculated. The mechanisms of thermal transformations of the caffeic chemisorbed surface complexes are proposed. Thermal decomposition of caffeic acid complex chemisorbed through grafted ester group proceeds via three parallel reactions, producing ketene, vinyl and acetylene derivatives of 1,2-dihydroxybenzene. Immobilization of phenolic acids on the silica surface improves greatly their thermal stability. PMID:26939077

  11. Matrix assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) for direct visualization of plant metabolites in situ

    SciTech Connect

    Sturtevant, Drew; Lee, Young -Jin; Chapman, Kent D.

    2015-11-22

    Direct visualization of plant tissues by matrix assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) has revealed key insights into the localization of metabolites in situ. Recent efforts have determined the spatial distribution of primary and secondary metabolites in plant tissues and cells. Strategies have been applied in many areas of metabolism including isotope flux analyses, plant interactions, and transcriptional regulation of metabolite accumulation. Technological advances have pushed achievable spatial resolution to subcellular levels and increased instrument sensitivity by several orders of magnitude. Furthermore, it is anticipated that MALDI-MSI and other MSI approaches will bring a new level of understanding to metabolomics as scientists will be encouraged to consider spatial heterogeneity of metabolites in descriptions of metabolic pathway regulation.

  12. Direct thermal desorption in the analysis of cheese volatiles by gas chromatography and gas chromatography-mass spectrometry: comparison with simultaneous distillation-extraction and dynamic headspace.

    PubMed

    Valero, E; Sanz, J; Martínez-Castro, I

    2001-06-01

    Direct thermal desorption (DTD) has been used as a technique for extracting volatile components of cheese as a preliminary step to their gas chromatographic (GC) analysis. In this study, it is applied to different cheese varieties: Camembert, blue, Chaumes, and La Serena. Volatiles are also extracted using other techniques such as simultaneous distillation-extraction and dynamic headspace. Separation and identification of the cheese components are carried out by GC-mass spectrometry. Approximately 100 compounds are detected in the examined cheeses. The described results show that DTD is fast, simple, and easy to automate; requires only a small amount of sample (approximately 50 mg); and affords quantitative information about the main groups of compounds present in cheeses. PMID:11396685

  13. Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid identification of Beta-hemolytic streptococci.

    PubMed

    Cherkaoui, Abdessalam; Emonet, Stéphane; Fernandez, José; Schorderet, Didier; Schrenzel, Jacques

    2011-08-01

    This study was undertaken to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the rapid identification of beta-hemolytic streptococci. We compared Bruker Biotyper 2.0 with Vitek2 coupled to the agglutination test. MALDI-TOF MS analysis of 386 beta-hemolytic streptococcal isolates yielded high-confidence identification to the species level for all 386 isolates. The Vitek2 gave high-confidence identification to the species level for 88% of Streptococcus agalactiae isolates (n = 269/306), 92% of Streptococcus pyogenes isolates (n = 48/52), and 39% of isolates of Streptococcus dysgalactiae serogroups C and G (n = 11/28). PMID:21697322

  14. Evaluation of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Identification of Nontuberculous Mycobacteria from Clinical Isolates

    PubMed Central

    Ruiz-Serrano, María Jesús; Marín, Mercedes; López Roa, Paula; Rodríguez-Créixems, Marta; Bouza, Emilio

    2015-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for the identification of nontuberculous mycobacterial (NTM) isolates was evaluated in this study. Overall, 125 NTM isolates were analyzed by MALDI-TOF and GenoType CM/AS. Identification by 16S rRNA/hsp65 sequencing was considered the gold standard. Agreements between MALDI-TOF and GenoType CM/AS with the reference method were, respectively, 94.4% and 84.0%. In 17 cases (13.6%), results provided by GenoType and MALDI-TOF were discordant; however, the reference method agreed with MALDI-TOF in 16/17 cases (94.1%; P = 0.002). PMID:26063855

  15. Nanostructured indium tin oxide slides for small-molecule profiling and imaging mass spectrometry of metabolites by surface-assisted laser desorption ionization MS.

    PubMed

    López de Laorden, Carlos; Beloqui, Ana; Yate, Luis; Calvo, Javier; Puigivila, Maria; Llop, Jordi; Reichardt, Niels-Christian

    2015-01-01

    Due to their electrical conductivity and optical transparency, slides coated with a thin layer of indium tin oxide (ITO) are the standard substrate for protein imaging mass spectrometry on tissue samples by MALDI-TOF MS. We have now studied the rf magnetron sputtering deposition parameters to prepare ITO thin films on glass substrates with the required nanometric surface structure for their use in the matrix-free imaging of metabolites and small-molecule drugs, without affecting the transparency required for classical histology. The custom-made surfaces were characterized by atomic force microscopy, scanning electron microscopy, ellipsometry, UV, and laser desorption ionization MS (LDI-MS) and employed for the LDI-MS-based analysis of glycans and druglike molecules, the quantification of lactose in milk by isotopic dilution, and metabolite imaging on mouse brain tissue samples. PMID:25411795

  16. In-situ Probing of Radiation-induced Processing of Organics in Astrophysical Ice Analogs—Novel Laser Desorption Laser Ionization Time-of-flight Mass Spectroscopic Studies

    NASA Astrophysics Data System (ADS)

    Gudipati, Murthy S.; Yang, Rui

    2012-09-01

    Understanding the evolution of organic molecules in ice grains in the interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons and ions is critical to our understanding of the connection between ISM and solar systems. Our study is aimed at reaching this goal of looking directly into radiation-induced processing in these ice grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar to matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe molecules embedded in water-ice at 5 K show for the first time that hydrogenation and oxygenation are the primary chemical reactions that occur in astrophysical ice analogs when subjected to Lyα radiation. We found that hydrogenation can occur over several unsaturated bonds and the product distribution corresponds to their stabilities. Multiple hydrogenation efficiency is found to be higher at higher temperatures (100 K) compared to 5 K—close to the interstellar ice temperatures. Hydroxylation is shown to have similar efficiencies at 5 K or 100 K, indicating that addition of O atoms or OH radicals to pre-ionized PAHs is a barrierless process. These studies—the first glimpses into interstellar ice chemistry through analog studies—show that once accreted onto ice grains PAHs lose their PAH spectroscopic signatures through radiation chemistry, which could be one of the reason for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks.

  17. Tailor-Made Stable Zr(IV)-Based Metal-Organic Frameworks for Laser Desorption/Ionization Mass Spectrometry Analysis of Small Molecules and Simultaneous Enrichment of Phosphopeptides.

    PubMed

    Chen, Lianfang; Ou, Junjie; Wang, Hongwei; Liu, Zhongshan; Ye, Mingliang; Zou, Hanfa

    2016-08-10

    Although thousands of metal-organic frameworks (MOFs) have been fabricated and widely applied in gas storage/separations, adsorption, catalysis, and so on, few kinds of MOFs have been used as adsorption materials while simultaneously serving as matrixes to analyze small molecules for laser desorption/ionization mass spectrometry (LDI-MS). Herein, a new concept is introduced to design and synthesize MOFs as both adsorption materials and matrixes according to the structure of ligands and common matrixes. The proof of concept design was demonstrated by selection of 2,5-pyridinedicarboxylic acid (PDC) and 2,5-dihydroxyterephthalic acid (DHT) as ligands for synthesis of MOFs. Two Zr(IV)-based MOFs of UiO-66-PDC and UiO-66-(OH)2 were synthesized and applied for the first time as new matrixes for analysis of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Both of them showed low matrix interferences, high ionization efficiency, and good reproducibility when used as matrixes. A variety of small molecules, including saccharides, amino acids, nucleosides, peptides, alkaline drugs, and natural products, were analyzed. In addition, UiO-66-(OH)2 exhibited potential for application in the quantitative determination of glucose and pyridoxal 5'-phosphate. Furthermore, thanks to its intrinsically large surface area and highly ordered pores, UiO-66-(OH)2 also showed sensitive and specific enrichment of phosphopeptides prior to MS analysis. These results demonstrated that this strategy can be used to efficiently screen tailor-made MOFs as matrixes to analyze small molecules by MALDI-TOF-MS. PMID:27427857

  18. Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Le, Cuong H.; Han, Jun; Borchers, Christoph H.

    2013-01-01

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided. PMID:24300588

  19. Small protein biomarkers of culture in Bacillus spores detected using capillary liquid chromatography coupled with matrix assisted laser desorption/ionization mass spectrometry.

    PubMed

    Wunschel, David; Wahl, Jon; Willse, Alan; Valentine, Nancy; Wahl, Karen

    2006-10-20

    Capillary liquid chromatography (cLC) coupled with matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF-MS) was used to compare small proteins and peptides extracted from Bacillus subtilis spores grown on four different media. A single, efficient protein separation, compatible with MALDI-MS analysis, was employed to reduce competitive ionization between proteins, and thus interrogate more proteins than possible using direct MALDI-MS. The MALDI-MS data files for each fraction are assembled as two-dimensional data sets of retention time and mass information. This method of visualizing small protein data required careful attention to background correction as well as mass and retention time variability. The resulting data sets were used to create comparative displays of differences in protein profiles between different spore preparations. Protein differences were found between two different solid media in both phase bright and phase dark spore phenotype. The protein differences between two different liquid media were also examined. As an extension of this method, we have demonstrated that candidate protein biomarkers can be trypsin digested to provide identifying peptide fragment information following the cLC-MALDI experiment. We have demonstrated this method on two markers and utilized acid breakdown information to identify one additional marker for this organism. The resulting method can be used to identify discriminating proteins as potential biomarkers of growth media, which might ultimately be used for source attribution. PMID:16798120

  20. Rapid Identification of Bacteria from Positive Blood Culture Bottles by Use of Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Fingerprinting▿ †

    PubMed Central

    Christner, Martin; Rohde, Holger; Wolters, Manuel; Sobottka, Ingo; Wegscheider, Karl; Aepfelbacher, Martin

    2010-01-01

    Early and adequate antimicrobial therapy has been shown to improve the clinical outcome in bloodstream infections (BSI). To provide rapid pathogen identification for targeted treatment, we applied matrix-assisted laser desorption-ionization time of flight (MALDI-TOF) mass spectrometry fingerprinting to bacteria directly recovered from blood culture bottles. A total of 304 aerobic and anaerobic blood cultures, reported positive by a Bactec 9240 system, were subjected in parallel to differential centrifugation with subsequent mass spectrometry fingerprinting and reference identification using established microbiological methods. A representative spectrum of bloodstream pathogens was recovered from 277 samples that grew a single bacterial isolate. Species identification by direct mass spectrometry fingerprinting matched reference identification in 95% of these samples and worked equally well for aerobic and anaerobic culture bottles. Application of commonly used score cutoffs to classify the fingerprinting results led to an identification rate of 87%. Mismatching mostly resulted from insufficient bacterial numbers and preferentially occurred with Gram-positive samples. The respective spectra showed low concordance to database references and were effectively rejected by score thresholds. Spiking experiments and examination of the respective study samples even suggested applicability of the method to mixed cultures. With turnaround times around 100 min, the approach allowed for reliable pathogen identification at the day of blood culture positivity, providing treatment-relevant information within the critical phase of septic illness. PMID:20237093

  1. Proteogenomic biomarkers for identification of Francisella species and subspecies by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry.

    PubMed

    Durighello, Emie; Bellanger, Laurent; Ezan, Eric; Armengaud, Jean

    2014-10-01

    Francisella tularensis is the causative agent of tularemia. Because some Francisella strains are very virulent, this species is considered by the Centers for Disease Control and Prevention to be a potential category A bioweapon. A mass spectrometry method to quickly and robustly distinguish between virulent and nonvirulent Francisella strains is desirable. A combination of shotgun proteomics and whole-cell matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry on the Francisella tularensis subsp. holarctica LVS defined three protein biomarkers that allow such discrimination: the histone-like protein HU form B, the 10 kDa chaperonin Cpn10, and the 50S ribosomal protein L24. We established that their combined detection by whole-cell MALDI-TOF spectrum could enable (i) the identification of Francisella species, and (ii) the prediction of their virulence level, i.e., gain of a taxonomical level with the identification of Francisella tularensis subspecies. The detection of these biomarkers by MALDI-TOF mass spectrometry is straightforward because of their abundance and the absence of other abundant protein species closely related in terms of m/z. The predicted molecular weights for the three biomarkers and their presence as intense peaks were confirmed with MALDI-TOF/MS spectra acquired on Francisella philomiragia ATCC 25015 and on Francisella tularensis subsp. tularensis CCUG 2112, the most virulent Francisella subspecies. PMID:25215633

  2. Dithranol as a matrix for matrix assisted laser desorption/ionization imaging on a fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Le, Cuong H; Han, Jun; Borchers, Christoph H

    2013-01-01

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided. PMID:24300588

  3. Evaluation of matrix-assisted laser desorption/ionization time of flight mass spectrometry for characterization of Culicoides nubeculosus biting midges.

    PubMed

    Kaufmann, C; Ziegler, D; Schaffner, F; Carpenter, S; Pflüger, V; Mathis, A

    2011-03-01

    Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has shown promise in species identification of insect species. We evaluated its potential to consistently characterize laboratory-reared biting midges of the species Culicoides nubeculosus (Meigen) (Diptera: Ceratopogonidae). Twenty-one reproducible potential biomarker masses for C. nubeculosus were identified under different experimental treatments. These treatments included the homogenization of insects in either water or known concentrations of formic acid. The biomarker masses were present independent of age, gender and different periods of storage of individuals in 70% ethanol (a standard preservation method). It was found that the presence of blood in females reduced the intensity of the MALDI-TOF pattern, necessitating the removal of the abdomen before analysis. The protein profiles of a related non-biting midge, Forcipomyia sp. (Diptera: Ceratopogonidae), and of Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) mosquitoes were also examined and were distinctly different. These findings provide preliminary data to optimize future studies in differentiation of species within the Culicoides genus using MALDI-TOF MS which is a rapid, simple, reliable and cost-effective technique. PMID:21118284

  4. Petroleomic Analysis of Bio- Oils from the Fast Pyrolysis or Biomass: Laser Desorption Ionization-Linear Ion Trap-Orbitrap mass Spectrometry Approach

    SciTech Connect

    Smith, Erica A.; Lee, Young Jin

    2010-08-23

    Fast pyrolysis of biomass produces bio-oils that can be upgraded into biofuels. Despite similar physical properties to petroleum, the chemical properties of bio-oils are quite different and their chemical compositions, particularly those of non-volatile compounds, are not well-known. Here, we report the first time attempt at analyzing bio-oils using high-resolution mass spectrometry (MS), which employed laser desorption ionization-linear ion trap-Orbitrap MS. Besides a few limitations, we could determine chemical compositions for over 100 molecular compounds in a bio-oil sample produced from the pyrolysis of a loblolly pine tree. These compounds consist of 3-6 oxygens and 9-17 double-bond equivalents (DBEs). Among those, O{sub 4} compounds with a DBE of 9-13 were most abundant. Unlike petroleum oils, the lack of nearby molecules within a {+-}2 Da mass window for major components enabled clear isolation of precursor ions for subsequent MS/MS structural investigations. Petroleomic analysis and a comparison to low-mass components in hydrolytic lignin suggest that they are dimers and trimers of depolymerized lignin.

  5. Mass spectrometry of oligopeptides in the presence of large amounts of alkali halides using desorption/ionization induced by neutral cluster impact.

    PubMed

    Portz, André; Baur, Markus; Gebhardt, Christoph R; Dürr, Michael

    2016-06-01

    Oligopeptides in the presence of large amounts of salt were desorbed and ionized using desorption/ionization induced by neutral clusters (DINeC) for further analysis by means of mass spectrometry (MS). Using oligopeptides in alkali halide solutions as a model system, DINeC was shown to yield clear and fragmentation free mass spectra of the biomolecules even from environments with a large excess of salt. The results were traced back to a phase separation between salt and biomolecules during sample preparation. The ratio between alkali metal complexes [M+A](+) and bare biomolecules [M+H](+) was controlled using different preparation schemes. DINeC was applied to the products of a tryptic digest of bovine serum albumin in the presence of sodium chloride; the results of a mass fingerprint analysis did not show a major difference for the spectra with and without salt in the original solution. The metal-ion/peptide interaction was further investigated by means of tandem-MS. PMID:26825286

  6. Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS)

    PubMed Central

    Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

    2015-01-01

    Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures. PMID:26271045

  7. Nanomanipulation-Coupled Matrix-Assisted Laser Desorption/ Ionization-Direct Organelle Mass Spectrometry: A Technique for the Detailed Analysis of Single Organelles

    NASA Astrophysics Data System (ADS)

    Phelps, Mandy S.; Sturtevant, Drew; Chapman, Kent D.; Verbeck, Guido F.

    2016-02-01

    We describe a novel technique combining precise organelle microextraction with deposition and matrix-assisted laser desorption/ionization (MALDI) for a rapid, minimally invasive mass spectrometry (MS) analysis of single organelles from living cells. A dual-positioner nanomanipulator workstation was utilized for both extraction of organelle content and precise co-deposition of analyte and matrix solution for MALDI-direct organelle mass spectrometry (DOMS) analysis. Here, the triacylglycerol (TAG) profiles of single lipid droplets from 3T3-L1 adipocytes were acquired and results validated with nanoelectrospray ionization (NSI) MS. The results demonstrate the utility of the MALDI-DOMS technique as it enabled longer mass analysis time, higher ionization efficiency, MS imaging of the co-deposited spot, and subsequent MS/MS capabilities of localized lipid content in comparison to NSI-DOMS. This method provides selective organellar resolution, which complements current biochemical analyses and prompts for subsequent subcellular studies to be performed where limited samples and analyte volume are of concern.

  8. Small protein biomarkers of culture in Bacillus spores detected using capillary liquid chromatography coupled with matrix assisted laser desorption/ionization mass spectrometry

    SciTech Connect

    Wunschel, David S.; Wahl, Jon H.; Willse, Alan R.; Valentine, Nancy B.; Wahl, Karen L.

    2006-10-20

    Capillary liquid chromatography (cLC) coupled with matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (TOF-MS) was used to compare small proteins and peptides extracted from Bacillus subtilis spores grown on four different media. A single, efficient protein separation, compatible with MALDI-MS analysis, was employed to reduce competitive ionization between proteins, and thus interrogate more proteins than possible using direct MALDI-MS. The MALDI-MS data files for each fraction are assembled as two dimensional data sets of retention time and mass information. This method of visualizing small protein data required careful attention to background correction as well as mass and retention time variability. The resulting data sets were used to create comparative displays of differences in protein profiles between different spore preparations. Protein differences were found between two different solid media in both phase bright and phase dark conditions. The protein differences between two different liquid media were also examined. As an extension of this method, we have demonstrated that candidate protein biomarkers can be trypsin digested to provide identifying peptide fragment information following the cLC-MALDI experiment. We have demonstrated this method on two markers and utilized acid breakdown information to identify one additional marker for this organism. The resulting method can be used to identify discriminating proteins as potential biomarkers of growth media, which might ultimately be used for source attribution.

  9. Negative Ion In-Source Decay Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry for Sequencing Acidic Peptides

    NASA Astrophysics Data System (ADS)

    McMillen, Chelsea L.; Wright, Patience M.; Cassady, Carolyn J.

    2016-05-01

    Matrix-assisted laser desorption/ionization (MALDI) in-source decay was studied in the negative ion mode on deprotonated peptides to determine its usefulness for obtaining extensive sequence information for acidic peptides. Eight biological acidic peptides, ranging in size from 11 to 33 residues, were studied by negative ion mode ISD (nISD). The matrices 2,5-dihydroxybenzoic acid, 2-aminobenzoic acid, 2-aminobenzamide, 1,5-diaminonaphthalene, 5-amino-1-naphthol, 3-aminoquinoline, and 9-aminoacridine were used with each peptide. Optimal fragmentation was produced with 1,5-diaminonphthalene (DAN), and extensive sequence informative fragmentation was observed for every peptide except hirudin(54-65). Cleavage at the N-Cα bond of the peptide backbone, producing c' and z' ions, was dominant for all peptides. Cleavage of the N-Cα bond N-terminal to proline residues was not observed. The formation of c and z ions is also found in electron transfer dissociation (ETD), electron capture dissociation (ECD), and positive ion mode ISD, which are considered to be radical-driven techniques. Oxidized insulin chain A, which has four highly acidic oxidized cysteine residues, had less extensive fragmentation. This peptide also exhibited the only charged localized fragmentation, with more pronounced product ion formation adjacent to the highly acidic residues. In addition, spectra were obtained by positive ion mode ISD for each protonated peptide; more sequence informative fragmentation was observed via nISD for all peptides. Three of the peptides studied had no product ion formation in ISD, but extensive sequence informative fragmentation was found in their nISD spectra. The results of this study indicate that nISD can be used to readily obtain sequence information for acidic peptides.

  10. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using an inorganic particle matrix for small molecule analysis

    PubMed

    Kinumi; Saisu; Takayama; Niwa

    2000-03-01

    Fine metal or metal oxide powder as an alternative to conventional organic matrices in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) has been utilized successfully for lower molecular mass analytes, poly(ethylene glycol) 200 (PEG 200) and methyl stearate. Eleven kinds of particle, Al, Mn, Mo, Si, Sn, SnO2, TiO2, W, WO3, Zn and ZnO, were evaluated. The analyte was mixed with a metal or metal oxide powder (inorganic matrix) with particle diameter of tens of micrometers and liquid dispersant, followed by application to the sample target. Using a commercial MALDI-TOFMS instrument equipped with an internal 337 nm pulsed nitrogen laser, the analytes, PEG 200 and methyl stearate, were ionized as the alkali metal ion adducted molecules [M+Na]+ or [M+K]+ when the inorganic matrices Mn, Mo, Si, Sn, TiO2, W, WO3, Zn or ZnO were used. In the case of an Al matrix, PEG 200 was ionized as [M+K]+, whereas methyl stearate was ionized as [M+H]+ and [M+Al]+. These particles have potential as the matrix for MALDI. During our examination, however, only SnO2 particles did not ionize either PEG 200 or methyl stearate. Based on our protocol, when TiO2 powder was suspended with liquid paraffin, PEG 200 and methyl stearate gave their MALDI-TOF mass spectra with the lowest background noise and highest intensity. TiO2 powder seemed to be a broad potential matrix for low molecular mass polar or non-polar analytes. The results suggested that bulk particles caused rapid heating/vaporization processes and ionized analyte molecules under irradiation with a pulsed UV laser. The present method can be readily applied to obtain the low background noise MALDI-TOF mass spectra of small-sized compounds. PMID:10767772

  11. Matrix-assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) Mass Spectrometric Analysis of Intact Proteins Larger than 100 kDa

    PubMed Central

    Signor, Luca; Boeri Erba, Elisabetta

    2013-01-01

    Effectively determining masses of proteins is critical to many biological studies (e.g. for structural biology investigations). Accurate mass determination allows one to evaluate the correctness of protein primary sequences, the presence of mutations and/or post-translational modifications, the possible protein degradation, the sample homogeneity, and the degree of isotope incorporation in case of labelling (e.g. 13C labelling). Electrospray ionisation (ESI) mass spectrometry (MS) is widely used for mass determination of denatured proteins, but its efficiency is affected by the composition of the sample buffer. In particular, the presence of salts, detergents, and contaminants severely undermines the effectiveness of protein analysis by ESI-MS. Matrix-assisted laser desorption/ionization (MALDI) MS is an attractive alternative, due to its salt tolerance and the simplicity of data acquisition and interpretation. Moreover, the mass determination of large heterogeneous proteins (bigger than 100 kDa) is easier by MALDI-MS due to the absence of overlapping high charge state distributions which are present in ESI spectra. Here we present an accessible approach for analysing proteins larger than 100 kDa by MALDI-time of flight (TOF). We illustrate the advantages of using a mixture of two matrices (i.e. 2,5-dihydroxybenzoic acid and α-cyano-4-hydroxycinnamic acid) and the utility of the thin layer method as approach for sample deposition. We also discuss the critical role of the matrix and solvent purity, of the standards used for calibration, of the laser energy, and of the acquisition time. Overall, we provide information necessary to a novice for analysing intact proteins larger than 100 kDa by MALDI-MS. PMID:24056304

  12. Misidentification of a Rare Species, Cryptococcus laurentii, by Commonly Used Commercial Biochemical Methods and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Systems: Challenges for Clinical Mycology Laboratories.

    PubMed

    Xiao, Meng; Fan, Xin; Chen, Xin-Xin; Wang, He; Zhang, Li; Xu, Zhi-Peng; Kudinha, Timothy; Kong, Fanrong; Xu, Ying-Chun

    2016-01-01

    Forty-two putative Cryptococcus laurentii isolates identified by the Vitek 2 system were collected in China. The gold standard, internal transcribed spacer (ITS) sequencing, confirmed that only two isolates were genuine C. laurentii. Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry was able to identify the C. laurentii isolates with an expanded custom database. PMID:26560541

  13. Misidentification of a Rare Species, Cryptococcus laurentii, by Commonly Used Commercial Biochemical Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Systems: Challenges for Clinical Mycology Laboratories

    PubMed Central

    Xiao, Meng; Fan, Xin; Chen, Xin-Xin; Wang, He; Zhang, Li; Xu, Zhi-Peng; Kudinha, Timothy; Kong, Fanrong

    2015-01-01

    Forty-two putative Cryptococcus laurentii isolates identified by the Vitek 2 system were collected in China. The gold standard, internal transcribed spacer (ITS) sequencing, confirmed that only two isolates were genuine C. laurentii. Bruker Biotyper matrix-assisted laser desorption ionization–time of flight mass spectrometry was able to identify the C. laurentii isolates with an expanded custom database. PMID:26560541

  14. Bacteriophage cell lysis of Shiga toxin-producing Escherichia coli for top-down proteomic identification of Shiga toxin 1 & 2 using matrix-assisted laser desorption/ionization tandem time-of-light mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RATIONALE: Analysis of bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) often relies upon sample preparation methods that result in cell lysis, e.g. bead-beating. However, Shiga toxin-producing Escherichia coli (STEC) can undergo bacteriophage...

  15. Top-down proteomic identification of Shiga toxin 2 subtypes from Shiga toxin-producing Escherichia coli by Matrix-Assisted Laser Desorption Ionization-Tandem Time of Flight mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have analyzed 26 Shiga toxin-producing Escherichia coli (STEC) strains for Shiga toxin 2 (Stx2) production using matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomic analysis. STEC strains were induced to ...

  16. Simultaneous detection of phosphatidylcholines and glycerolipids using matrix-enhanced surface-assisted laser desorption/ionization-mass spectrometry with sputter-deposited platinum film.

    PubMed

    Ozawa, Tomoyuki; Osaka, Issey; Ihozaki, Taisuke; Hamada, Satoshi; Kuroda, Yusuke; Murakami, Tatsuya; Miyazato, Akio; Kawasaki, Hideya; Arakawa, Ryuichi

    2015-11-01

    Matrix-assisted laser desorption/ionisation (MALDI) imaging mass spectrometry (IMS) allows for the simultaneous detection and imaging of several molecules in brain tissue. However, the detection of glycerolipids such as diacylglycerol (DAG) and triacylglycerol (TAG) in brain tissues is hindered in MALDI-IMS because of the ion suppression effect from excessive ion yields of phosphatidylcholine (PC). In this study, we describe an approach that employs a homogeneously deposited metal nanoparticle layer (or film) for the detection of glycerolipids in rat brain tissue sections using IMS. Surface-assisted laser desorption/ionisation IMS with sputter-deposited Pt film (Pt-SALDI-IMS) for lipid analysis was performed as a solvent-free and organic matrix-free method. Pt-SALDI produced a homogenous layer of nanoparticles over the surface of the rat brain tissue section. Highly selective detection of lipids was possible by MALDI-IMS and Pt-SALDI-IMS; MALDI-IMS detected the dominant ion peak of PC in the tissue section, and there were no ion peaks representing glycerolipids such as DAG and TAG. In contrast, Pt-SALDI-IMS allowed the detection of these glycerolipids, but not PC. Therefore, using a hybrid method combining MALDI and Pt-SALDI (i.e., matrix-enhanced [ME]-Pt-SALDI-IMS), we achieved the simultaneous detection of PC, PE and DAG in rat brain tissue sections, and the sensitivity for the detection of these molecules was better than that of MALDI-IMS or Pt-SALDI alone. The present simple ME-Pt-SALDI approach for the simultaneous detection of PC and DAG using two matrices (sputter-deposited Pt film and DHB matrix) would be useful in imaging analyses of biological tissue sections. PMID:26505771

  17. Carbon Dots and 9AA as a Binary Matrix for the Detection of Small Molecules by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, Yongli; Gao, Dan; Bai, Hangrui; Liu, Hongxia; Lin, Shuo; Jiang, Yuyang

    2016-07-01

    Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analyze small molecules have some limitations, due to the inhomogeneous analyte/matrix co-crystallization and interference of matrix-related peaks in low m/z region. In this work, carbon dots (CDs) were for the first time applied as a binary matrix with 9-Aminoacridine (9AA) in MALDI MS for small molecules analysis. By 9AA/CDs assisted desorption/ionization (D/I) process, a wide range of small molecules, including nucleosides, amino acids, oligosaccharides, peptides, and anticancer drugs with a higher sensitivity were demonstrated in the positive ion mode. A detection limit down to 5 fmol was achieved for cytidine. 9AA/CDs matrix also exhibited excellent reproducibility compared with 9AA matrix. Moreover, by exploring the ionization mechanism of the matrix, the influence factors might be attributed to the four parts: (1) the strong UV absorption of 9AA/CDs due to their π-conjugated network; (2) the carboxyl groups modified on the CDs surface act as protonation sites for proton transfer in positive ion mode; (3) the thin layer crystal of 9AA/CDs could reach a high surface temperature more easily and lower transfer energy for LDI MS; (4) CDs could serve as a matrix additive to suppress 9AA ionization. Furthermore, this matrix was allowed for the analysis of glucose as well as nucleosides in human urine, and the level of cytidine was quantified with a linear range of 0.05-5 mM (R2 > 0.99). Therefore, the 9AA/CDs matrix was proven to be an effective MALDI matrix for the analysis of small molecules with improved sensitivity and reproducibility. This work provides an alternative solution for small molecules detection that can be further used in complex samples analysis.

  18. Magnetic solid phase extraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human body fluids.

    PubMed

    Chen, Di; Zheng, Hao-Bo; Huang, Yun-Qing; Hu, Yu-Ning; Yu, Qiong-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-08-21

    Ambient ionization techniques show good potential in rapid analysis of target compounds. However, a direct application of these ambient ionization techniques for the determination of analytes in a complex matrix is difficult due to the matrix interference and ion suppression. To resolve this problem, here we developed a strategy by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI)-mass spectrometry (MS). As a proof of concept, the pyrrole-coated Fe3O4 magnetic nanoparticles (Fe3O4@Ppy) were prepared and used for the extraction of antidepressants. After extraction, the Fe3O4@Ppy with trapped antidepressants was then directly subjected to DCBI-MS analysis with the aid of a homemade magnetic glass capillary. As the MSPE process is rapid and the direct DCBI-MS analysis does not need solvent desorption or chromatographic separation processes, the overall analysis can be completed within 3 min. The proposed MSPE-DCBI-MS method was then successfully used to determine antidepressants in human urine and plasma. The calibration curves were obtained in the range of 0.005-0.5 μg mL(-1) for urine and 0.02-1 μg mL(-1) for plasma with reasonable linearity (R(2) > 0.951). The limits of detection of three antidepressants were in the range of 0.2-1 ng mL(-1) for urine and 2-5 ng mL(-1) for plasma. Acceptable reproducibility for rapid analysis was achieved with relative standard deviations less than 19.1% and the relative recoveries were 85.2-118.7%. Taken together, the developed MSPE-DCBI-MS strategy offers a powerful capacity for rapid analysis of target compounds in a complex matrix, which would greatly expand the applications of ambient ionization techniques with plentiful magnetic sorbents. PMID:26145704

  19. Analyses of functional polymer-modified nanoparticles for protein sensing by surface-assisted laser desorption/ionization mass spectrometry coupled with HgTe nanomatrices.

    PubMed

    Chang, Hsiang-Yu; Huang, Ming-Feng; Hsu, Chia-Lun; Huang, Chih-Ching; Chang, Huan-Tsung

    2015-06-01

    In this study, we employed HgTe nanostructure-based matrices (nanomartrices; NMs) for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) for the analyses of polyethylene glycol (PEG) derivatives as well as thiol-PEG-modified gold nanoparticles (PEG-Au NPs). Relative to common organic matrices, the use of HgTe NMs as the matrix for SALDI-MS resulted in more highly efficient analyses of PEG derivatives, in terms of sensitivity and reproducibility. The symmetric MS profiles of PEG (Mw: ca. 8000 Da) obtained through HgTe NMs/SALDI-MS analysis revealed the absence of polymer degradation during this process. Under optimal conditions, the HgTe NMs/SALDI-MS system enabled the detection of PEG sample as low as 100 pg and with molecular weights of up to approximately 42,000 Da. We also used this approach for the analyses of PEG-Au NPs in which various functional groups (carboxymethyl, amine, biotin) were present at the PEG termini, revealing that the combination of SALDI-MS and HgTe NMs have great potential for use in the characterization of modified polymer-ligands on nanomaterials. We also demonstrated the PEG-Au NPs can be coupled with HgTe NMs/SALDI-MS for characterization of biorecognition events. After avidin, the target protein, had been selectively captured by the biotin-PEG-Au NPs, we found that the desorption/ionization efficiency of biotin-PEG from the Au NP surface was suppressed; accordingly, this novel SALDI-MS approach allows rapid detection of avidin with high specificity and sensitivity. Au NP surfaces functionalized with other functional-PEG ligands might also allow amplification of signals from other biological interactions. PMID:25896538

  20. Sensitive method for quantification of octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in end-exhaled air by thermal desorption gas chromatography mass spectrometry.

    PubMed

    Biesterbos, Jacqueline W H; Beckmann, Gwendolyn; Anzion, Rob B M; Ragas, Ad M J; Russel, Frans G M; Scheepers, Paul T J

    2014-06-17

    Octamethylcyclotetrasiloxane (D4) and decamethylpentasiloxane (D5) are used as ingredients for personal care products (PCPs). Because of the use of these PCPs, consumers are exposed daily to D4 and D5. A sensitive analytical method was developed for analysis of D4 and D5 in end-exhaled air by thermal desorption gas chromatography mass spectrometry (TD-GC-MS), to determine the internal dose for consumer exposure assessment. Fifteen consumers provided end-exhaled air samples that were collected using Bio-VOC breath samplers and subsequently transferred to automatic thermal desorption (ATD) tubes. Prior to use, the ATD tubes were conditioned for a minimum of 4 h at 350 °C. The TD unit and auto sampler were coupled to a GC-MS using electron ionization. Calibration was performed using 0-10 ng/μL solutions of D4/D5 and (13)C-labeled D4/D5 as internal standards. The ions monitored were m/z 281 for D4, 355 for D5, 285 for (13)C-labeled D4, and 360 for (13)C-labeled D5. The addition of internal standard reduced the coefficient of variation from 30.8% to 9.5% for D4 and from 37.8% to 12.5% for D5. The limit of quantification was 2.1 ng/L end-exhaled air for D4 and 1.4 ng/L end-exhaled air for D5. With this method, cyclic siloxanes (D4 and D5) can be quantified in end-exhaled air at concentrations as low as background levels observed in the general population. PMID:24833048

  1. Carbon Dots and 9AA as a Binary Matrix for the Detection of Small Molecules by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

    PubMed

    Chen, Yongli; Gao, Dan; Bai, Hangrui; Liu, Hongxia; Lin, Shuo; Jiang, Yuyang

    2016-07-01

    Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analyze small molecules have some limitations, due to the inhomogeneous analyte/matrix co-crystallization and interference of matrix-related peaks in low m/z region. In this work, carbon dots (CDs) were for the first time applied as a binary matrix with 9-Aminoacridine (9AA) in MALDI MS for small molecules analysis. By 9AA/CDs assisted desorption/ionization (D/I) process, a wide range of small molecules, including nucleosides, amino acids, oligosaccharides, peptides, and anticancer drugs with a higher sensitivity were demonstrated in the positive ion mode. A detection limit down to 5 fmol was achieved for cytidine. 9AA/CDs matrix also exhibited excellent reproducibility compared with 9AA matrix. Moreover, by exploring the ionization mechanism of the matrix, the influence factors might be attributed to the four parts: (1) the strong UV absorption of 9AA/CDs due to their π-conjugated network; (2) the carboxyl groups modified on the CDs surface act as protonation sites for proton transfer in positive ion mode; (3) the thin layer crystal of 9AA/CDs could reach a high surface temperature more easily and lower transfer energy for LDI MS; (4) CDs could serve as a matrix additive to suppress 9AA ionization. Furthermore, this matrix was allowed for the analysis of glucose as well as nucleosides in human urine, and the level of cytidine was quantified with a linear range of 0.05-5 mM (R(2) > 0.99). Therefore, the 9AA/CDs matrix was proven to be an effective MALDI matrix for the analysis of small molecules with improved sensitivity and reproducibility. This work provides an alternative solution for small molecules detection that can be further used in complex samples analysis. Graphical Abstract ᅟ. PMID:27075876

  2. Carbon Dots and 9AA as a Binary Matrix for the Detection of Small Molecules by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, Yongli; Gao, Dan; Bai, Hangrui; Liu, Hongxia; Lin, Shuo; Jiang, Yuyang

    2016-04-01

    Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analyze small molecules have some limitations, due to the inhomogeneous analyte/matrix co-crystallization and interference of matrix-related peaks in low m/z region. In this work, carbon dots (CDs) were for the first time applied as a binary matrix with 9-Aminoacridine (9AA) in MALDI MS for small molecules analysis. By 9AA/CDs assisted desorption/ionization (D/I) process, a wide range of small molecules, including nucleosides, amino acids, oligosaccharides, peptides, and anticancer drugs with a higher sensitivity were demonstrated in the positive ion mode. A detection limit down to 5 fmol was achieved for cytidine. 9AA/CDs matrix also exhibited excellent reproducibility compared with 9AA matrix. Moreover, by exploring the ionization mechanism of the matrix, the influence factors might be attributed to the four parts: (1) the strong UV absorption of 9AA/CDs due to their π-conjugated network; (2) the carboxyl groups modified on the CDs surface act as protonation sites for proton transfer in positive ion mode; (3) the thin layer crystal of 9AA/CDs could reach a high surface temperature more easily and lower transfer energy for LDI MS; (4) CDs could serve as a matrix additive to suppress 9AA ionization. Furthermore, this matrix was allowed for the analysis of glucose as well as nucleosides in human urine, and the level of cytidine was quantified with a linear range of 0.05-5 mM (R2 > 0.99). Therefore, the 9AA/CDs matrix was proven to be an effective MALDI matrix for the analysis of small molecules with improved sensitivity and reproducibility. This work provides an alternative solution for small molecules detection that can be further used in complex samples analysis.

  3. Characterization of low-molecular weight iodine-terminated polyethylenes by gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with the use of derivatization.

    PubMed

    Zaikin, Vladimir G; Borisov, Roman S; Polovkov, Nikolai Yu; Zhilyaev, Dmitry I; Vinogradov, Aleksei A; Ivanyuk, Aleksei V

    2013-01-01

    Gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry, in conjunction with various derivatization approaches, have been applied to structure determination of individual oligomers and molecular-mass distributions (MMD) in low-molecular mass polyethylene having an iodine terminus. Direct GC/MS analysis has shown that the samples under investigation composed of polyethyelene-iodides (major components) and n-alkanes. Exchange reaction with methanol in the presence of NaOH gave rise to methoxy-derivatives and n-alkenes. Electron ionization mass spectra have shown that the former contained terminal methoxy groups indicating the terminal position of the iodine atom in the initial oligomers. MMD parameters have been determined with the aid of MALDI mass spectrometry followed by preliminary derivatization-formation of covalently bonded charge through the reaction of iodides with triphenylphosphine, trialkylamines, pyridine or quinoline. The mass spectra revealed well-resolved peaks for cationic parts of derivatized oligomers allowing the determination of MMD. The latter values have been compared with those calculated from GC/MS data. PMID:24308197

  4. ENUMERATION OF CARBOHYDRATE HYDROXYL GROUPS BY SILYLATION AND MATRIX ASSISTED LASER DESORPTION/IONIZATION TIME-OF-FLIGHT MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A method for enumerating hydroxyl group in analytes is described and applied to various carbohydrates and polyols. The analytes were derivatized in solution by using trimethylsilylimidazole (TMSI) and the products were analyzed without chromatography in a MALDI-TOF-MS. The mass spectra revealed co...

  5. Detection of bacteria from biological mixtures using immunomagnetic separation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    USGS Publications Warehouse

    Madonna, A.J.; Basile, F.; Furlong, E.; Voorhees, K.J.

    2001-01-01

    A rapid method for identifying specific bacteria from complex biological mixtures using immunomagnetic separation coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been developed. The technique employs commercially available magnetic beads coated with polycolonal antibodies raised against specific bacteria and whole cell analysis by MALDI-MS. A suspension of a bacterial mixture is mixed with the immunomagnetic beads specific for the target microorganism. After a short incubation period (20 mins) the bacteria captured by the beads are washed, resuspended in deionized H2O and directly applied onto a MALDI probe. Liquid suspensions containing bacterial mixtures can be screened within 1 h total analysis time. Positive tests result in the production of a fingerprint mass spectrum primarily consisting of protein biomarkers characteristic of the targeted microorganism. Using this procedure, Salmonella choleraesuis was isolated and detected from standard bacterial mixtures and spiked samples of river water, human urine, and chicken blood. Copyright ?? 2001 John Wiley & Sons, Ltd.

  6. Quantitative mutant analysis of viral quasispecies by chip-based matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry

    PubMed Central

    Amexis, Georgios; Oeth, Paul; Abel, Kenneth; Ivshina, Anna; Pelloquin, Francois; Cantor, Charles R.; Braun, Andreas; Chumakov, Konstantin

    2001-01-01

    RNA viruses exist as quasispecies, heterogeneous and dynamic mixtures of mutants having one or more consensus sequences. An adequate description of the genomic structure of such viral populations must include the consensus sequence(s) plus a quantitative assessment of sequence heterogeneities. For example, in quality control of live attenuated viral vaccines, the presence of even small quantities of mutants or revertants may indicate incomplete or unstable attenuation that may influence vaccine safety. Previously, we demonstrated the monitoring of oral poliovirus vaccine with the use of mutant analysis by PCR and restriction enzyme cleavage (MAPREC). In this report, we investigate genetic variation in live attenuated mumps virus vaccine by using both MAPREC and a platform (DNA MassArray) based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Mumps vaccines prepared from the Jeryl Lynn strain typically contain at least two distinct viral substrains, JL1 and JL2, which have been characterized by full length sequencing. We report the development of assays for characterizing sequence variants in these substrains and demonstrate their use in quantitative analysis of substrains and sequence variations in mixed virus cultures and mumps vaccines. The results obtained from both the MAPREC and MALDI-TOF methods showed excellent correlation. This suggests the potential utility of MALDI-TOF for routine quality control of live viral vaccines and for assessment of genetic stability and quantitative monitoring of genetic changes in other RNA viruses of clinical interest. PMID:11593021

  7. ARTICLES: Influence Factors on Particle Growth for On-line Aerosol Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xia, Wei-wei; Ti, Ru-fang; Zhang, Zi-Iiang; Zheng, Hai-yang; Fang, Li

    2010-06-01

    An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometer for on-line bioaerosol detection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the condenser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of biological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detection that has the potential to provide rapid and reliable identification of airborne biological aerosols.

  8. Two-step matrix application technique to improve ionization efficiency for matrix-assisted laser desorption/ionization in imaging mass spectrometry.

    PubMed

    Sugiura, Yuki; Shimma, Shuichi; Setou, Mitsutoshi

    2006-12-15

    A novel matrix application protocol for direct tissue mass spectrometry is presented. Matrix-assisted laser desorption/ionization is a popular ionization procedure for direct tissue analysis and imaging mass spectrometry. Usually, matrixes are applied by dispensing droplets through either pipettes or automated dispensing machines, or by airbrushing. These techniques are very simple, but it was difficult to obtain uniform matrix crystals on the tissue surface, and nonuniform crystals degrade the spectrum qualities. Here we report a new matrix application protocol, which is a combination of spraying and dispensing droplets, and we have succeeded in overcoming these problems in conventional matrix applications on tissue surfaces. We call our new technique the "spray-droplet method". In this technique, tiny matrix crystals formed by spraying act as seeds for crystal growth. Our technique leads to matrix spots that are filled homogeneously with minute crystals. Such matrix crystals dramatically improve peak intensity and signal-to-noise ratio. In an example on a rat brain section, the number of detectable peaks was increased and signal intensity of m/z 5440 in our method was approximately 30.6 times higher than that in conventional methods. We used this spray-droplet method with a chemical ink-jet technology for matrix deposition to succeed in MALDI imaging of signals, which were undetectable from the conventional matrix applications. PMID:17165811

  9. Structural characterisation of tyrosine-nitrated peptides by ultraviolet and infrared matrix-assisted laser desorption/ionisation Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Petre, Brínduşa-Alina; Youhnovski, Nikolay; Lukkari, Juho; Weber, Reinhold; Przybylski, Michael

    2005-01-01

    Nitration of tyrosine residues in proteins may occur in cells upon oxidative stress and inflammation processes mediated through generation of reactive nitroxyl from peroxynitrite. Tyrosine nitration from oxidative pathways may generate cytotoxic species that cause protein dysfunction and pathogenesis. A number of protein nitrations in vivo have been reported and some specific Tyrosine nitration sites have been recently identified using mass spectrometric methods. High-resolution Fourier transform ion cyclotron resonance mass spectrometry (MALDI) FT-ICR-MS) is shown here to be a highly efficient method in the determination of protein nitrations. Following the identification of nitration of the catalytic site Tyr-430 residue of bovine prostacyclin synthase, we synthesised several model peptides containing both unmodified tyrosine and 3-nitro-tyrosine residues, using solid-phase peptide synthesis (SPPS). The structures of the nitrotyrosine peptides were characterised both by ESI- and by matrix-assisted laser desorption/ionisation (MALDI)-FT-ICR-MS, using a standard ultraviolet (UV) nitrogen nitrogen laser and a 2.97 microm Nd-YAG infrared laser. Using UV-MALDI-MS, 3-nitrotyrosyl-peptides were found to undergo extensive photochemical fragmentation at the nitrophenyl group, which may hamper or prevent the unequivocal identification of Tyr-nitrations in cellular proteins. In contrast, infrared-MALDI-FT-ICR-MS did not produce fragmentation of molecular ions of Tyr-nitrated peptides. PMID:16322657

  10. The value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in identifying clinically relevant bacteria: a comparison with automated microbiology system

    PubMed Central

    Zhou, Chunmei; Huang, Shenglei; Shan, Yuzhang; Ye, Xiangru

    2014-01-01

    Background Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been developed as a new-type soft ionization mass spectrometry in the recent year. Increasing number of clinical microbiological laboratories consider it as an innovate approach for bacterial identification. Methods A total of 876 clinical strains, comprising 52 species in 27 genus, were obtained from Fudan University Affiliated Zhongshan Hospital. We compared the identification accuracy of the Vitek MS system (bioMerieux, Marcy l’Etoile) to other conventional methods for bacterial identification. 16S rRNA gene sequencing was performed as a reference identification method in cases of discrepant results. Results The Vitek MS system consistently produced accurate results within minutes of loading, while conventional methods required several hours to produce identification results. Among the 876 isolates, the overall performance of Vitek MS was significantly better than the conventional method both for correct species identification (830, 94.7% vs. 746, 85.2%, respectively, P=0.000). Conclusions Compared to traditional identification methods, MALDI-TOF MS is a rapid, accurate and economical technique to enhance the clinical value of microorganism identification. PMID:24822117

  11. Simple, Efficient, and Cost-Effective Multiplex Genotyping with Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry of Hemoglobin Beta Gene Mutations

    PubMed Central

    Thongnoppakhun, Wanna; Jiemsup, Surasak; Yongkiettrakul, Suganya; Kanjanakorn, Chompunut; Limwongse, Chanin; Wilairat, Prapon; Vanasant, Anusorn; Rungroj, Nanyawan; Yenchitsomanus, Pa-thai

    2009-01-01

    A number of common mutations in the hemoglobin β (HBB) gene cause β-thalassemia, a monogenic disease with high prevalence in certain ethnic groups. As there are 30 HBB variants that cover more than 99.5% of HBB mutant alleles in the Thai population, an efficient and cost-effective screening method is required. Three panels of multiplex primer extensions, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were developed. The first panel simultaneously detected 21 of the most common HBB mutations, while the second panel screened nine additional mutations, plus seven of the first panel for confirmation; the third panel was used to confirm three HBB mutations, yielding a 9-Da mass difference that could not be clearly distinguished by the previous two panels. The protocol was both standardized using 40 samples of known genotypes and subsequently validated in 162 blind samples with 27 different genotypes (including a normal control), comprising heterozygous, compound heterozygous, and homozygous β-thalassemia. Results were in complete agreement with those from the genotyping results, conducted using three different methods overall. The method developed here permitted the detection of mutations missed using a single genotyping procedure. The procedure should serve as the method of choice for HBB genotyping due to its accuracy, sensitivity, and cost-effectiveness, and can be applied to studies of other gene variants that are potential disease biomarkers. PMID:19460936

  12. Continuous Flow Atmospheric Pressure Laser Desorption/Ionization Using a 6–7-µm-Band Mid-Infrared Tunable Laser for Biomolecular Mass Spectrometry

    PubMed Central

    Hiraguchi, Ryuji; Hazama, Hisanao; Senoo, Kenichirou; Yahata, Yukinori; Masuda, Katsuyoshi; Awazu, Kunio

    2014-01-01

    A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O–H, C=O, CH3 and C–N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS). PMID:24937686

  13. Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry†

    PubMed Central

    Jin, Zhicheng; Daiya, Shivani; Kenttämaa, Hilkka I.

    2011-01-01

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H2O)+ chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5α-cholestane, cholesta-3,5-diene, squalene, and β-carotene, were found to solely form the desired water replacement product (adduct-H2O) with the ClMn(H2O)+ ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H2O ions, but less abundant adduct-2H2O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H2O)+ chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids. PMID:21528012

  14. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25507326

  15. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25420342

  16. 1,5-Diaminonaphthalene hydrochloride assisted laser desorption/ionization mass spectrometry imaging of small molecules in tissues following focal cerebral ischemia.

    PubMed

    Liu, Huihui; Chen, Rui; Wang, Jiyun; Chen, Suming; Xiong, Caiqiao; Wang, Jianing; Hou, Jian; He, Qing; Zhang, Ning; Nie, Zongxiu; Mao, Lanqun

    2014-10-21

    A sensitive analytical technique for visualizing small endogenous molecules simultaneously is of great significance for clearly elucidating metabolic mechanisms during pathological progression. In the present study, 1,5-naphthalenediamine (1,5-DAN) hydrochloride was prepared for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) of small molecules in liver, brain, and kidneys from mice. Furthermore, 1,5-DAN hydrochloride assisted LDI MSI of small molecules in brain tissue of rats subjected to middle cerebral artery occlusion (MCAO) was carried out to investigate the altered metabolic pathways and mechanisms underlying the development of ischemic brain damage. Our results suggested that the newly prepared matrix possessed brilliant features including low cost, strong ultraviolet absorption, high salt tolerance capacity, and fewer background signals especially in the low mass range (typically m/z < 500), which permitted us to visualize the spatial distribution of a broad range of small molecule metabolites including metal ions, amino acids, carboxylic acids, nucleotide derivatives, peptide, and lipids simultaneously. Nineteen endogenous metabolites involved in metabolic networks such as ATP metabolism, tricarboxylic acid (TCA) cycle, glutamate-glutamine cycle, and malate-aspartate shuttle, together with metal ions and phospholipids as well as antioxidants underwent relatively obvious changes after 24 h of MCAO. The results were highly consistent with the data obtained by MRM MS analysis. These findings highlighted the promising potential of the organic salt matrix for application in the field of biomedical research. PMID:25247713

  17. Quantitative analysis of poly- and perfluoroalkyl compounds in water matrices using high resolution mass spectrometry: optimization for a laser diode thermal desorption method.

    PubMed

    Munoz, Gabriel; Vo Duy, Sung; Budzinski, Hélène; Labadie, Pierre; Liu, Jinxia; Sauvé, Sébastien

    2015-06-30

    An alternative analysis technique for the quantitation of 15 poly- and perfluoroalkyl substances (PFASs) in water matrices is reported. Analysis time between each sample was reduced to less than 20s, all target molecules being analyzed in a single run with the use of laser diode thermal desorption atmospheric pressure chemical ionization (LDTD/APCI) coupled with high resolution accurate mass (HRMS) orbitrap mass spectrometry. LDTD optimal settings were investigated using either one-factor-at-a-time or experimental design methodologies, while orbitrap parameters were optimized simultaneously by means of a Box-Behnken design. Following selection of an adequate sample concentration and purification procedure based on solid-phase extraction and graphite clean-up, the method was validated in an influent wastewater matrix. Environmentally significant limits of detection were reported (0.3-4ngL(-1) in wastewater and 0.03-0.2ngL(-1) in surface water) and out of the 15 target analytes, 11 showed excellent accuracies (±20% of the target values) and recovery rates (75-125%). The method was successfully applied to a selection of environmental samples, including wastewater samples in 7 locations across Canada, as well as surface and tap water samples from the Montreal region, providing insights into the degree of PFAS contamination in this area. PMID:26041525

  18. Characterization of partially transesterified poly(beta-hydroxyalkanoate)s using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Saeed; Ayorinde; Eribo; Gordon; Collier

    1999-10-15

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used for the characterization of a partially transesterified poly(beta-hydroxyalkanoate), PHA, polymer produced by the bacterial strain Alcaligenes eutrophus using saponified vegetable oils as the sole carbon sources. The transesterification was carried out separately under acidic and basic conditions to obtain PHA oligomers weighing less than 10 kDa. The intact oligomers were detected in their cationized [M + Na](+) and [M + K](+) forms by MALDI-TOFMS. A composition analysis, using the MALDI-TOF spectra, indicate that the oligomers obtained via acid catalysis were terminated with a methyl 3-hydroxybutyrate end group, and those obtained by base catalysis had a methyl crotonate (olefinic) termination. In addition to HB (hydroxy butyrate), the oligomers were found to contain a small percentage of HV (hydroxy valerate). This was independently confirmed using gas chromatography/mass spectrometry (GC/MS). In comparison, the analysis of a commercial PHA polymer, transesterified under identical conditions, only showed the presence of HB, i.e. a pure PHB homopolymer. Copyright 1999 John Wiley & Sons, Ltd. PMID:10487942

  19. Ammonium Sulfate Improves Detection of Hydrophilic Quaternary Ammonium Compounds through Decreased Ion Suppression in Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry.

    PubMed

    Sugiyama, Eiji; Masaki, Noritaka; Matsushita, Shoko; Setou, Mitsutoshi

    2015-11-17

    Hydrophilic quaternary ammonium compounds (QACs) include derivatives of carnitine (Car) or choline, which are known to have essential bioactivities. Here we developed a technique for improving the detection of hydrophilic QACs using ammonium sulfate (AS) in matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). In MALDI mass spectrometry for brain homogenates, the addition of AS greatly increased the signal intensities of Car, acetylcarnitine (AcCar), and glycerophosphocholine (GPC) by approximately 300-, 700-, and 2500-fold. The marked improvement required a higher AS concentration than that needed for suppressing the potassium adduction on phosphatidylcholine and 2,5-dihydroxybenzoic acid. Adding AS also increased the signal intensities of Car, AcCar, and GPC by approximately 10-, 20-, and 40-fold in MALDI-IMS. Consequently, the distributions of five hydrophilic QACs (Car, AcCar, GPC, choline, and phosphocholine) were simultaneously visualized by this technique. The distinct mechanism from other techniques such as improved matrix application, derivatization, or postionization suggests the great potential of AS addition to achieve higher sensitivity of MALDI-IMS for various analytes. PMID:26492538

  20. Improvement of identification of Capnocytophaga canimorsus by matrix-assisted laser desorption ionization-time of flight mass spectrometry using enriched database.

    PubMed

    Magnette, Amandine; Huang, Te-Din; Renzi, Francesco; Bogaerts, Pierre; Cornelis, Guy R; Glupczynski, Youri

    2016-01-01

    Capnocytophaga canimorsus and Capnocytophaga cynodegmi can be transmitted from dogs or cats and cause serious human infections. We aimed to evaluate the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF