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Sample records for aerosol mass spectrometric

  1. Chemical Nature Of Titan’s Organic Aerosols Constrained from Spectroscopic and Mass Spectrometric Observations

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, D. P.

    2012-10-01

    The Cassini-Huygens observations greately extend our knowledge about Titan’s organic aerosols. The Cassini INMS and CAPS observations clearly demonstrate the formation of large organic molecules in the ionosphere [1, 2]. The VIMS and CIRS instruments have revealed spectral features of the haze covering the mid-IR and far-IR wavelengths [3, 4, 5, 6]. This study attempts to speculate the possible chemical nature of Titan’s aerosols by comparing the currently available observations with our laboratory study. We have conducted a series of cold plasma experiment to investigate the mass spectrometric and spectroscopic properties of laboratory aerosol analogs [7, 8]. Titan tholins and C2H2 plasma polymer are generated with cold plasma irradiations of N2/CH4 and C2H2, respectively. Laser desorption mass spectrum of the C2H2 plasma polymer shows a reasonable match with the CAPS positive ion mass spectrum. Furthermore, spectroscopic features of the the C2H2 plasma polymer in mid-IR and far-IR wavelegths qualitatively show reasonable match with the VIMS and CIRS observations. These results support that the C2H2 plasma polymer is a good candidate material for Titan’s aerosol particles at the altitudes sampled by the observations. We acknowledge funding supports from the NASA Cassini Data Analysis Program, NNX10AF08G, and from the NASA Exobiology Program, NNX09AM95G, and the Cassini Project. [1] Waite et al. (2007) Science 316, 870-875. [2] Crary et al. (2009) Planet. Space Sci. 57, 1847-1856. [3] Bellucci et al. (2009) Icarus 201, 198-216. [4] Anderson and Samuelson (2011) Icarus 212, 762-778. [5] Vinatier et al. (2010) Icarus 210, 852-866. [6] Vinatier et al. (2012) Icarus 219, 5-12. [7] Imanaka et al. (2004) Icarus 168, 344-366. [8] Imanaka et al. (2012) Icarus 218, 247-261.

  2. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W; Williams, Peter; Krone, Jennifer Reeve

    2007-12-04

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  3. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W; Williams, Peter; Krone, Jennifer Reeve

    2013-07-16

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  4. Mass spectrometric immunoassay

    DOEpatents

    Nelson, Randall W.; Williams, Peter; Krone, Jennifer Reeve

    2005-12-13

    Rapid mass spectrometric immunoassay methods for detecting and/or quantifying antibody and antigen analytes utilizing affinity capture to isolate the analytes and internal reference species (for quantification) followed by mass spectrometric analysis of the isolated analyte/internal reference species. Quantification is obtained by normalizing and calibrating obtained mass spectrum against the mass spectrum obtained for an antibody/antigen of known concentration.

  5. Mass spectrometric approaches for chemical characterisation of atmospheric aerosols: critical review of the most recent advances

    SciTech Connect

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A.

    2012-06-29

    This manuscript presents an overview of the most recent instrument developments for the field and laboratory applications of mass spectrometry (MS) to investigate the chemistry and physics of atmospheric aerosols. A range of MS instruments, employing different sample introduction methods, ionisation and mass detection techniques are used both for ‘online’ and ‘offline’ characterisation of aerosols. Online MS techniques enable detection of individual particles with simultaneous measurement of particle size distributions and aerodynamic characteristics and are ideally suited for field studies that require high temporal resolution. Offline MS techniques provide a means for detailed molecular-level analysis of aerosol samples, which is essential to gain fundamental knowledge regarding aerosol chemistry, mechanisms of particle formation and atmospheric aging. Combined, complementary MS techniques provide comprehensive information on the chemical composition, size, morphology and phase of aerosols – data of key importance for evaluating hygroscopic and optical properties of particles, their health effects, understanding their origins and atmospheric evolution. Over the last few years, developments and applications of MS techniques in aerosol research have expanded remarkably as evident by skyrocketing publication statistics. Finally, the goal of this review is to present the most recent developments in the field of aerosol mass spectrometry for the time period of late 2010 to early 2012, which have not been conveyed in previous reviews.

  6. Ultrahigh resolution mass spectrometric characterization of organic aerosol from European and Chinese cities

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Huang, Ru-Jin; Hoffmann, Thorsten

    2016-04-01

    Organic aerosol constitutes a substantial fraction (20-90%) of submicrometer aerosol mass, playing an important role in air quality and human health. Over the past few years, ultra-high resolution mass spectrometry (UHRMS) has been applied to elucidate the chemical composition of ambient aerosols. However, most of the UHRMS studies used direct infusion without prior separation by liquid chromatography, which may cause the loss of individual compound information and interference problems. In the present study, urban ambient aerosol with particle diameter < 2.5 μm was collected in Mainz, Germany and Beijing, China, respectively. Two pretreatment procedures were applied to extract the organic compounds from the filter samples: One method uses a mixture of acetonitrile and water, the other uses pure water and prepared for the extraction of humic-like substances. The extracts were analyzed by ultra-high-performance liquid chromatography coupled with an Orbitrap mass spectrometer in both negative and the positive modes. The effects of pretreatment procedures on the characterization of organic aerosol and the city-wise difference in chemical composition of organic aerosol will be discussed in detail.

  7. Identification of characteristic mass spectrometric markers for primary biological aerosol particles and comparison with field data from submicron pristine aerosol particles

    NASA Astrophysics Data System (ADS)

    Freutel, F.; Schneider, J.; Zorn, S. R.; Drewnick, F.; Borrmann, S.; Hoffmann, T.; Martin, S. T.

    2009-04-01

    The contribution of primary biological aerosol (PBA) to the total aerosol particle concentration is estimated to range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that PBA is a major source of particles in the supermicron range, and is also an important fraction of the submicron aerosol. PBA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. For this reason we have performed mass spectrometric laboratory measurements (Aerodyne C-ToF and W-ToF AMS, single particle laser ablation instrument SPLAT) on pure submicron aerosol particles containing typical PBA compounds in order to identify typical mass spectral patterns of these compounds and to explain the observed fragmentation patterns on the basis of molecular structures. These laboratory data were compared to submicron particle mass spectra obtained during AMAZE-08 (Amazonian Aerosol CharacteriZation Experiment, Brazil, February/March 2008). The results indicate that characteristic m/z ratios for carbohydrates (e.g., glucose, saccharose, levoglucosan, mannitol) can be identified, for example m/z = 60(C2H4O2+) or m/z = 61(C2H5O2+). Certain characteristic peaks for amino acids were also identified in the laboratory experiments. In the field data from AMAZE-08, these characteristic peaks for carbohydrates and amino acids were found, and their contribution to the total organic mass was estimated to about 5%. Fragment ions from peptides and small proteins were also identified in laboratory experiments. Larger proteins, however, seem to become oxidized to CO2+ to a large extend in the vaporizing process of the AMS. Thus, detection of proteins in atmospheric aerosol particles with the AMS appears to be difficult.

  8. High-Resolution Mass Spectrometric Analysis of Secondary Organic Aerosol Produced by Ozonation of Limonene

    SciTech Connect

    Walser, Maggie L.; Dessiaterik, Yury; Laskin, Julia; Laskin, Alexander; Nizkorodov, Serguei

    2008-02-08

    Secondary organic aerosol (SOA) particles formed from the ozone-initiated oxidation of limonene are characterized by high-resolution electrospray ionization mass spectrometry in both the positive and negative ion modes. The mass spectra reveal a large number of both monomeric (m/z < 300) and oligomeric (m/z > 300) products of oxidation. A combination of high resolving power (m/Δm ~60,000) and Kendrick mass defect analysis makes it possible to unambiguously determine the composition for hundreds of individual compounds in SOA samples. Van Krevelen analysis shows that the SOA compounds are heavily oxidized, with average O:C ratios of 0.43 and 0.50 determined from the positive and negative ion mode spectra, respectively. An extended reaction mechanism for the formation of the first generation SOA molecular components is proposed. The mechanism includes known isomerization and addition reactions of the carbonyl oxide intermediates generated during the ozonation of limonene, and numerous isomerization pathways for alkoxy radicals resulting from the decomposition of unstable carbonyl oxides. The isomerization reactions yield numerous products with a progressively increasing number of alcohol and carbonyl groups, whereas C-C bond scission reactions in alkoxy radicals shorten the carbon chain. Together these reactions yield a large number of isomeric products with broadly distributed masses. A qualitative agreement is found between the number and degree of oxidation of the predicted and measured reaction products in the monomer range.

  9. Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Weimer, S.; Drewnick, F.; Borrmann, S.; Helas, G.; Gwaze, P.; Schmid, O.; Andreae, M. O.; Kirchner, U.

    2006-12-01

    Various types of combustion-related particles in the size range between 100 and 850 nm were analyzed with an aerosol mass spectrometer and a differential mobility analyzer. The measurements were performed with particles originating from biomass burning, diesel engine exhaust, laboratory combustion of diesel fuel and gasoline, as well as from spark soot generation. Physical and morphological parameters like fractal dimension, effective density, bulk density and dynamic shape factor were derived or at least approximated from the measurements of electrical mobility diameter and vacuum aerodynamic diameter. The relative intensities of the mass peaks in the mass spectra obtained from particles generated by a commercial diesel passenger car, by diesel combustion in a laboratory burner, and by evaporating and re-condensing lubrication oil were found to be very similar. The mass spectra from biomass burning particles show signatures identified as organic compounds like levoglucosan but also others which are yet unidentified. The aerodynamic behavior yielded a fractal dimension (Df) of 2.09 +/- 0.06 for biomass burning particles from the combustion of dry beech sticks, but showed values around three, and hence more compact particle morphologies, for particles from combustion of more natural oak. Scanning electron microscope images confirmed the finding that the beech combustion particles were fractal-like aggregates, while the oak combustion particles displayed a much more compact shape. For particles from laboratory combusted diesel fuel, a Df value of 2.35 was found, for spark soot particles, Df [approximate] 2.10. The aerodynamic properties of fractal-like particles from dry beech wood combustion indicate an aerodynamic shape factor [chi] that increases with electrical mobility diameter, and a bulk density of 1.92 g cm-3. An upper limit of [chi] [approximate] 1.2 was inferred for the shape factor of the more compact particles from oak combustion.

  10. Mass spectrometric characterization of isomeric terpenoic acids from the oxidation of α-pinene, β-pinene, d-limonene, and Δ3-carene in fine forest aerosol.

    PubMed

    Yasmeen, Farhat; Szmigielski, Rafal; Vermeylen, Reinhilde; Gómez-González, Yadian; Surratt, Jason D; Chan, Arthur W H; Seinfeld, John H; Maenhaut, Willy; Claeys, Magda

    2011-04-01

    In this study, we present liquid chromatographic and mass spectral data for predominant terpenoic acids formed through oxidation of α-pinene, β-pinene, d-limonene, and Δ(3)-carene that occur in fine forest aerosol from K-puszta, Hungary, a rural site with coniferous vegetation. Characterization of these secondary organic aerosol tracers in fine ambient aerosol is important because it allows one to gain information on monoterpene precursors and source processes such as oxidation and aging processes. The mass spectral data were obtained using electrospray ionization in the negative ion mode, accurate mass measurements, and linear ion trap tandem mass spectrometric experiments. Emphasis is given to the mass spectrometric differentiation of isobaric terpenoic acids, such as, e.g. the molecular weight (MW) 186 terpenoic acids, cis-pinic, cis-caric, homoterpenylic, ketolimononic, and limonic acids. Other targeted isobaric terpenoic acids are the MW 184 terpenoic acids, cis-pinonic and cis-caronic acids, and the MW 204 tricarboxylic acids, 3-methyl-1,2,3-butanetricarboxylic and 3-carboxyheptanedioic acids. Fragmentation pathways are proposed to provide a rational explanation for the observed isomeric differences and/or to support the suggested tentative structures. For the completeness of the data set, data obtained for recently reported lactone-containing terpenoic acids (i.e. terpenylic and terebic acids), related or isobaric compounds (i.e. norpinic acid, diaterpenylic acid acetate, and unknown MW 188 compounds) are also included, the rationale being that other groups working on this topic could use this data compilation as a reference.

  11. Uptake of nitric acid, ammonia, and organics in orographic clouds: mass spectrometric analyses of droplet residual and interstitial aerosol particles

    NASA Astrophysics Data System (ADS)

    Schneider, Johannes; Mertes, Stephan; van Pinxteren, Dominik; Herrmann, Hartmut; Borrmann, Stephan

    2017-01-01

    Concurrent in situ analyses of interstitial aerosol and cloud droplet residues have been conducted at the Schmücke mountain site during the Hill Cap Cloud Thuringia campaign in central Germany in September and October 2010. Cloud droplets were sampled from warm clouds (temperatures between -3 and +16 °C) by a counterflow virtual impactor and the submicron-sized residues were analyzed by a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS), while the interstitial aerosol composition was measured by an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). During cloud-free periods, the submicron out-of-cloud aerosol was analyzed using both instruments, allowing for intercomparison between the two instruments. Further instrumentation included black carbon measurements and optical particle counters for the aerosol particles as well as optical sizing instrumentation for the cloud droplets. The results show that, under cloud conditions, on average 85 % of the submicron aerosol mass partitioned into the cloud liquid phase. Scavenging efficiencies of nitrate, ammonium, sulfate, and organics ranged between 60 and 100 %, with nitrate having, in general, the highest values. For black carbon, the scavenging efficiency was markedly lower (about 24 %). The nitrate and ammonium mass fractions were found to be markedly enhanced in cloud residues, indicating uptake of gaseous nitric acid and ammonia into the aqueous phase. This effect was found to be temperature dependent: at lower temperatures, the nitrate and ammonium mass fractions in the residues were higher. Also, the oxidation state of the organic matter in cloud residues was found to be temperature dependent: the O : C ratio was lower at higher temperatures. A possible explanation for this observation is a more effective uptake and/or higher concentrations of low-oxidized water-soluble volatile organic compounds, possibly of biogenic origin, at higher temperatures. Organic nitrates were observed

  12. Aerosol mass spectrometric features of biogenic SOA: observations from a plant chamber and in rural atmospheric environments.

    PubMed

    Kiendler-Scharr, Astrid; Zhang, Qi; Hohaus, Thorsten; Kleist, Einhard; Mensah, Amewu; Mentel, Thomas F; Spindler, Christian; Uerlings, Ricarda; Tillmann, Ralf; Wildt, Jürgen

    2009-11-01

    Secondary organic aerosol (SOA) is known to form from a variety of anthropogenic and biogenic precursors. Current estimates of global SOA production vary over 2 orders of magnitude. Since no direct measurement technique for SOA exists, quantifying SOA remains a challenge for atmospheric studies. The identification of biogenic SOA (BSOA) based on mass spectral signatures offers the possibility to derive source information of organic aerosol (OA) with high time resolution. Here we present data from simulation experiments. The BSOA from tree emissions was characterized with an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Collection efficiencies were close to 1, and effective densities of the BSOA were found to be 1.3 +/- 0.1 g/cm(3). The mass spectra of SOA from different trees were found to be highly similar. The average BSOA mass spectrum from tree emissions is compared to a BSOA component spectrum extracted from field data. It is shown that overall the spectra agree well and that the mass spectral features of BSOA are distinctively different from those of OA components related to fresh fossil fuel and biomass combustions. The simulation chamber mass spectrum may potentially be useful for the identification and interpretation of biogenic SOA components in ambient data sets.

  13. Mass Spectrometric Analysis of Pristine Aerosol Particles During the wet Season of Amazonia - Detection of Primary Biological Particles?

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Zorn, S. R.; Freutel, F.; Borrmann, S.; Chen, Q.; Farmer, D. K.; Jimenez, J. L.; Flores, M.; Roldin, P.; Artaxo, P.; Martin, S. T.

    2008-12-01

    The contribution of primary biological aerosol (POA) particles to the natural organic aerosol is a subject of current research. Estimations of the POA contribution to the total aerosol particle concentration range between 25 and 80%, depending on location and season. Especially in the tropical rain forest it is expected that POA is a major source of supermicron, possibly also of submicron particles. During AMAZE (Amazonian Aerosol CharacteriZation Experiment), a field project near Manaus, Brazil, in February/March 2008, an Aerodyne ToF-AMS was equipped with a high pressure aerodynamic lens. This high pressure lens (operating pressure 14.6 torr) is designed with the objective to extend the detectable size range of the AMS into the supermicron size range where primary biological particles are expected. Size distribution measured by the AMS were compared with size distribution from an optical particle counter and indicate that the high pressure lens has a 50% cut-off at a vacuum aerodynamic diameter of about 1 μm, but still has significant transmission up to a vacuum aerodynamic diameter of about 2 μm, thus extending the detectable size range of the AMS into the coarse mode. The measuring instruments were situated in a container at ground level. The aerosol was sampled through a 40 m vertical, laminar inlet, which was heated and dried to maintain a relative humidity between 30 and 40%. The inlet was equipped with a 7 μm cut-off cyclone. Size distributions recorded with an optical particle counter parallel to the AMS show that the inlet transmitted aerosol particles up to an optically detected diameter of 10 μm. POA particles like plant fragments, pollen, spores, fungi, viruses etc. contain chemical compounds as proteins, sugars, amino acids, chlorophyll, and cellular material as cellulose. Laboratory experiments have been performed in order to identify typical mass spectral patterns of these compounds. These laboratory data were compared to size resolved particle

  14. High-Resolution Aerosol Mass Spectrometric Measurements of the Arctic Troposphere on-board the NASA DC-8 during ARCTAS

    NASA Astrophysics Data System (ADS)

    Cubison, M. J.; Jimenez, J. L.

    2009-04-01

    A High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS, DeCarlo et al., Anal. Chem., 2006) was deployed aboard the NASA DC-8 research aircraft as part of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign during the spring and summer of 2008. The main focus of the spring phase, operated out of Fairbanks, Alaska, was to investigate the composition and sources of Arctic Haze (e.g. Quinn et al., Tellus B, 2007), a persistent pollution layer that accumulates under the stable springtime Polar High anti-cyclonic weather pattern. The sulphate-dominated aerosol in the Arctic Haze almost always contained smaller amounts of organic matter. Multiple biomass-burning plumes and some plumes from North-American pollution were observed. Comparison of tracers for biomass-burning in both the gas- and aerosol-phases show good correlation and point to the long-term persistence of organic aerosol of biomass-burning origin in the springtime Arctic. The organic aerosol was typically highly oxidized. During the summer phase, operated out of Palmdale, California, and Cold Lake, Canada, the focus was investigating California pollution and the composition and evolution of the outflow from large-scale boreal forest fires, respectively. However, the numerous fires burning in Northern California during the project timeframe allowed for the sampling of biomass-burning plumes from both locations. The persistence and correlation of the gas- and aerosol-phase fire markers observed during the spring phase was once again apparent. This observation, over a range of transport timescales and geographical locations, suggests that certain components of the AMS mass spectrum can be used as robust markers for biomass-burning in the organic aerosol composition. Measurements from multiple fires of aerosol chemical composition, including volatility profiles of important organic components, are compared to monitor the evolution of biomass

  15. Online and offline mass spectrometric study of the impact of oxidation and ageing on glyoxal chemistry and uptake onto ammonium sulfate aerosols.

    PubMed

    Hamilton, Jacqueline F; Baeza-Romero, M Teresa; Finessi, Emanuela; Rickard, Andrew R; Healy, Robert M; Peppe, Salvatore; Adams, Thomas J; Daniels, Mark J S; Ball, Stephen M; Goodall, Iain C A; Monks, Paul S; Borrás, Esther; Muñoz, Amalia

    2013-01-01

    Recent laboratory and modelling studies have shown that reactive uptake of low molecular weight alpha-dicarbonyls such as glyoxal (GLY) by aerosols is a potentially significant source of secondary organic aerosol (SOA). However, previous studies disagree in the magnitude of the uptake of GLY, the mechanism involved and the physicochemical factors affecting particle formation. In this study, the chemistry of GLY with ammonium sulfate (AS) in both bulk laboratory solutions and in aerosol particles is investigated. For the first time, Aerosol Time of Flight Mass Spectrometry (ATOFMS), a single particle technique, is used together with offline (ESI-MS and LC-MS2) mass spectrometric techniques to investigate the change in composition of bulk solutions of GLY and AS resulting from aqueous photooxidation by OH and from ageing of the solutions in the dark. The mass spectral ions obtained in these laboratory studies were used as tracers of GLY uptake and chemistry in AS seed particles in a series of experiments carried out under dark and natural irradiated conditions at the outdoor European Photo-reactor (EUPHORE). Glyoxal oligomers formed were not detected by the ATOFMS, perhaps due to inefficient absorption at the laser wavelength. However, the presence of organic nitrogen compounds, formed by reaction of GLY with ammonia was confirmed, resulting in an increase in the absorption efficiency of the aerosol, and this increased the number of particles successfully ionised by the ATOFMS. A number of light absorbing organic nitrogen species, including 1H-imidazole, 1H-imidazole-2-carboxaldehyde, 2,2'-bis-imidazole and a glyoxal substituted 2,2'-bisimidazole, previously identified in aqueous laboratory solutions, were also identified in chamber aerosol and formed on atmospherically relevant timescales. An additional compound, predicted to be 1,2,5-oxadiazole, had an enhanced formation rate when the chamber was open and is predicted to be formed via a light activated pathway

  16. Mass spectrometric immunoassay

    SciTech Connect

    Nelson, R.W.; Krone, J.R.; Bieber, A.L.; Williams, P.

    1995-04-01

    A new, general method of immunoassay is demonstrated. The approach is based on the microscale immunoaffinity capture of target antigens followed by mass-specific identification and quantitation using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Immunoaffinity capture of antigens effectively overcomes signal suppression effects typically encountered during traditional matrix-assisted laser desorption/ionization analysis of complex biological mixtures while simultaneously concentrating the analyte into a small volume. Sample incubation and processing methods were such that a typical analysis could be performed in less than 1 h while subnanomolar sensitivities were maintained. The technique has been used for the rapid, selective, and quantitative screening of human blood for the presence of myotoxin a, and Mojave toxin from the venoms of the prairie rattlesnake, Crotalus virdis virdis, and the Mojave rattlesnake, Crotalus scutulatus scutulatus. 18 refs., 8 figs.

  17. Effect of operation conditions of the drop-on-demand aerosol generator on aerosol characteristics: Pseudo-cinematographic and plasma mass spectrometric studies

    NASA Astrophysics Data System (ADS)

    Orlandini v. Niessen, Jan O.; Krone, Karin M.; Bings, Nicolas H.

    2014-02-01

    The recently presented drop-on-demand (DOD) aerosol generator overcomes some of the drawbacks of pneumatic nebulization, as its aerosol is no longer generated by gas-liquid interaction. In the current study, an advanced imaging technique is presented, based on a CCD camera equipped with magnifying telecentric optics to allow for fast, automated and precise aerosol characterization as well as fundamental studies on the droplet generation processes by means of pseudo-cinematography. The DOD aerosol generator is thoroughly characterized regarding its droplet size distribution, which shows few distinct populations rather than a continuous distribution. Other important figures, such as the Sauter diameter (D3,2) of 22 μm and the span of 0.4 were also determined. Additionally, the influence of the electrical operation conditions of the dosing device on the aerosol generation process is described. The number and volume of the generated droplets were found to be very reproducible and user-variable, e.g. from 17 to 27 μm (D3,2), within a span of 0.07-0.89. The performances of different setups of the DOD as liquid sample introduction system in ICP-MS are correlated to the respective achievable aerosol characteristics and are also compared to the performance of a state-of-the-art μ-flow nebulizer (EnyaMist). The DOD system allowed for improved sensitivity, but slightly elevated signal noise and overall comparable limits of detection. The results are critically discussed and future directions are outlined.

  18. Hyphenation of a EC / OC thermal-optical carbon analyzer to photo ionization time-of-flight mass spectrometry: a new off-line aerosol mass spectrometric approach for characterization of primary and secondary particulate matter

    NASA Astrophysics Data System (ADS)

    Diab, J.; Streibel, T.; Cavalli, F.; Lee, S. C.; Saathoff, H.; Mamakos, T.; Chow, J. C.; Chen, L.-W. A.; Watson, J. G.; Sippula, O.; Zimmermann, R.

    2015-01-01

    Source apportionment and exposure of primary and secondary aerosols remains a challenging research field. In particular, the organic composition of primary particles and the formation mechanism of secondary organic aerosols (SOA) warrant further investigations. Progress in this field is strongly connected to the development of novel analytical techniques. In this study an off-line aerosol mass spectrometric technique based on filter samples, a hyphenated thermal/optical analyzer-photo ionization time of flight mass spectrometer (PI-TOFMS) system, was developed. The approach extends the capability of the widely used PM carbon analysis (for elemental/organic carbon (EC / OC)) by enabling the investigation of evolved gaseous species with soft and selective (resonance enhanced multiphoton ionization, REMPI) and non-selective photo ionization (single photon ionization, SPI) techniques. SPI was tuned to be medium soft to achieve comparability with results obtained by electron ionization (EI) aerosol mass spectrometer (AMS). Different PM samples including wood combustion emission samples, smog chamber samples from the reaction of ozone with different SOA precursors, and ambient samples taken at Ispra, Italy in winter as well as in summer were tested. The EC / OC-PI-TOFMS technique increases the understanding of the processes during the thermal/optical analysis and identifies marker substances for the source apportionment. Composition of oligomeric or polymeric species present in PM can be investigated by the analysis of the thermally breakdown products. In case of wood combustion, in addition to the well-known markers at m/z ratios of 60 and 73, two new characteristic masses (m/z 70 and 98) have been revealed as potentially linked to biomass burning. All four masses were also the dominant signals in an ambient sample taken in winter time in Ispra, Italy, confirming the finding that wood burning for residential heating is a major source for particulate matter (PM) in

  19. Hyphenation of a EC / OC thermal-optical carbon analyzer to photo-ionization time-of-flight mass spectrometry: an off-line aerosol mass spectrometric approach for characterization of primary and secondary particulate matter

    NASA Astrophysics Data System (ADS)

    Diab, J.; Streibel, T.; Cavalli, F.; Lee, S. C.; Saathoff, H.; Mamakos, A.; Chow, J. C.; Chen, L.-W. A.; Watson, J. G.; Sippula, O.; Zimmermann, R.

    2015-08-01

    Source apportionment and characterization of primary and secondary aerosols remains a challenging research field. In particular, the organic composition of primary particles and the formation mechanism of secondary organic aerosols (SOAs) warrant further investigations. Progress in this field is strongly connected to the development of novel analytical techniques. In this study an off-line aerosol mass spectrometric technique based on filter samples, a hyphenated thermal-optical analyzer photo-ionization time-of-flight mass spectrometer (PI-TOFMS) system, was developed. The approach extends the capability of the widely used particulate matter (PM) carbon analysis (for elemental / organic carbon, EC / OC) by enabling the investigation of evolved gaseous species with soft and selective (resonance enhanced multi-photon ionization, REMPI) and non-selective photo-ionization (single-photon ionization, SPI) techniques. SPI was tuned to be medium soft to achieve comparability with results obtained by the electron ionization aerosol mass spectrometer (AMS). Different PM samples including wood combustion emission samples, smog chamber samples from the reaction of ozone with different SOA precursors, and ambient samples taken at Ispra, Italy, in winter as well as in summer were tested. The EC / OC-PI-TOFMS technique increases the understanding of the processes during thermal-optical analysis and identifies marker substances for the source apportionment. Composition of oligomeric or polymeric species present in PM can be investigated by the analysis of the thermal breakdown products. In the case of wood combustion, in addition to the well-known markers at m/z ratios of 60 and 73, two new characteristic masses (m/z 70 and 98) have been revealed as potentially linked to biomass burning. All four masses were also the dominant signals in an ambient sample taken in winter time in Ispra, Italy, confirming the finding that wood burning for residential heating is a major source of PM

  20. Mass Spectrometric Studies of Oxides

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    2012-01-01

    Current studies at NASA Glenn on oxide thermodynamics are discussed. Previous studies on the vaporization of B2O3 in reducing atmospheres led to inconsistent studies when B was used as a reductant. It is shown that liquid B2O3 does not wet B and a clear phase separation was noted in the Knudsen cell. This problem was solved by using FeB and Fe2B to supply a different and constant activity of B. The thermodynamic data thus derived are compared to quantum chemical composite calculations. A major problem in high temperature mass spectrometry is the determination of accurate ionization cross sections, particularly for molecules. The method of Deutsch and Mark shows promise and some sample calculations are discussed. Finally current studies on the thermodynamics of rare earth silicates are discussed. Here the problems are obtaining a measurable signal from SiO2 vaporization and non-equilibrium vaporization. The use of a Ta reducing agent provides a stronger signal, which is related to silica activity. The Whitman-Motzfeld relation adapted to KEMS measurements is applied to obtain equilibrium pressures.

  1. Enhanced aerodynamic reach of vapor and aerosol sampling for real-time mass spectrometric detection using Venturi-assisted entrainment and ionization.

    PubMed

    Forbes, Thomas P; Staymates, Matthew

    2017-03-08

    Venturi-assisted ENTrainment and Ionization (VENTI) was developed, demonstrating efficient entrainment, collection, and transport of remotely sampled vapors, aerosols, and dust particulate for real-time mass spectrometry (MS) detection. Integrating the Venturi and Coandă effects at multiple locations generated flow and analyte transport from non-proximate locations and more importantly enhanced the aerodynamic reach at the point of collection. Transport through remote sampling probes up to 2.5 m in length was achieved with residence times on the order of 10(-2) s to 10(-1) s and Reynolds numbers on the order of 10(3) to 10(4). The Venturi-assisted entrainment successfully enhanced vapor collection and detection by greater than an order of magnitude at 20 cm stand-off (limit of simple suction). This enhancement is imperative, as simple suction restricts sampling to the immediate vicinity, requiring close proximity to the vapor source. In addition, the overall aerodynamic reach distance was increased by approximately 3-fold over simple suction under the investigated conditions. Enhanced aerodynamic reach was corroborated and observed with laser-light sheet flow visualization and schlieren imaging. Coupled with atmospheric pressure chemical ionization (APCI), the detection of a range of volatile chemical vapors; explosive vapors; explosive, narcotic, and mustard gas surrogate (methyl salicylate) aerosols; and explosive dust particulate was demonstrated. Continuous real-time Venturi-assisted monitoring of a large room (approximately 90 m(2) area, 570 m(3) volume) was demonstrated for a 60-min period without the remote sampling probe, exhibiting detection of chemical vapors and methyl salicylate at approximately 3 m stand-off distances within 2 min of exposure.

  2. Mass Spectrometric Immunoassays in Characterization of Clinically Significant Proteoforms

    PubMed Central

    Trenchevska, Olgica; Nelson, Randall W.; Nedelkov, Dobrin

    2016-01-01

    Proteins can exist as multiple proteoforms in vivo, as a result of alternative splicing and single-nucleotide polymorphisms (SNPs), as well as posttranslational processing. To address their clinical significance in a context of diagnostic information, proteoforms require a more in-depth analysis. Mass spectrometric immunoassays (MSIA) have been devised for studying structural diversity in human proteins. MSIA enables protein profiling in a simple and high-throughput manner, by combining the selectivity of targeted immunoassays, with the specificity of mass spectrometric detection. MSIA has been used for qualitative and quantitative analysis of single and multiple proteoforms, distinguishing between normal fluctuations and changes related to clinical conditions. This mini review offers an overview of the development and application of mass spectrometric immunoassays for clinical and population proteomics studies. Provided are examples of some recent developments, and also discussed are the trends and challenges in mass spectrometry-based immunoassays for the next-phase of clinical applications. PMID:28248223

  3. A novel aerosol mass spectrometric approach - Analysis of the organic molecular signature of PM by coupling of thermal EC/OC-carbon analysis to photo-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zimmermann, R.; Grabowski, J.; Streibel, T.; Sklorz, M.; Chow, J.

    2012-12-01

    Carbonaceous material in airborne particulate matter (PM) is of increasing interest e.g. due to its adverse health effects and its potential influence on the climate. Its analytical assessment on a molecular level is still very challenging. Hence, analysis of carbonaceous fractions for many studies is often solely carried out by determining sum parameters such as the overall content of organic carbon (OC) and elemental carbon (EC) as well as the total carbon content, TC (sum of OC and EC). The used thermal procedure, however, allows getting additional interesting information: By defining different thermal OC fractions (i.e. temperature steps) also information on the refractory properties of the carbonaceous material is obtained. In this context it is particularly interesting to investigate the release and formation behaviors of the molecular species responsible for the different OC and EC fractions. Thus after initial promising results of pre-studies [1,2] in the current work an EC/OC carbon analyzer (Model DRI 2000) and a homebuilt photo-ionization time-of-flight mass spectrometer (PI-TOFMS) were hyphenated and applied to investigate individual organic compounds especially from the different OC fractions. The carbon analyzer enables the stepwise heating of PM loaded filter samples and provides the sum values of the "carbon" release ("Improve protocol" [2]: OC1 - 120 °C, OC2 - 250°C, OC3 - 450°C OC4 - 550°C). With the on-line coupled PI-TOFMS evolved organic compounds, as released during the thermal program, are detectable in real time. This is possible by MS with soft photo ionization methods (SPI - single photon ionization and REMPI - resonance-enhanced multi photon ionization). Soft ionization suppresses fragmentation upon the ionization step and generates molecular signatures in the MS. The EC/OC-analyzer-PI-TOFMS instrument was applied to several types of PM samples, such as ambient aerosol, emission samples (gasoline/diesel car, wood combustion) or

  4. Mass-spectrometric measurements for nuclear safeguards

    SciTech Connect

    Carter, J.A.; Smith, D.H.; Walker, R.L.

    1982-01-01

    The need of an on-site inspection device to provide isotopic ratio measurements led to the development of a quadrupole mass spectrometer mounted in a van. This mobile laboratory has the ability, through the use of the resin bead technique, to acquire, prepare, and analyze samples of interest to nuclear safeguards. Precision of the measurements is about 1 to 2%.

  5. Mass Spectrometric Analysis of Histone Proteoforms

    NASA Astrophysics Data System (ADS)

    Yuan, Zuo-Fei; Arnaudo, Anna M.; Garcia, Benjamin A.

    2014-06-01

    Histones play important roles in chromatin, in the forms of various posttranslational modifications (PTMs) and sequence variants, which are called histone proteoforms. Investigating modifications and variants is an ongoing challenge. Previous methods are based on antibodies, and because they usually detect only one modification at a time, they are not suitable for studying the various combinations of modifications on histones. Fortunately, mass spectrometry (MS) has emerged as a high-throughput technology for histone analysis and does not require prior knowledge about any modifications. From the data generated by mass spectrometers, both identification and quantification of modifications, as well as variants, can be obtained easily. On the basis of this information, the functions of histones in various cellular contexts can be revealed. Therefore, MS continues to play an important role in the study of histone proteoforms. In this review, we discuss the analysis strategies of MS, their applications on histones, and some key remaining challenges.

  6. Electrospray tandem mass spectrometric investigations of morphinans.

    PubMed

    Raith, Klaus; Neubert, Reinhard; Poeaknapo, Chotima; Boettcher, Christian; Zenk, Meinhart H; Schmidt, Jürgen

    2003-11-01

    In this study positive ESI tandem mass spectra of the [M + H]+ ions of morphinan alkaloids obtained using an ion trap MS were compared with those from a triple quadrupole MS. This allows to assess the differences of the tandem-in-time versus the tandem-in-space principle, often hampering the development of ESI MS/MS libraries. Fragmentation pathways and possible fragment ion structures were discussed. In order to obtain elemental composition, accurate mass measurements were performed. According to the MS/MS fragmentation pathway, the investigated compounds can be grouped into 4 subsets: (1) morphine and codeine, (2) morphinone, codeinone, and neopinone, (3) thebaine and oripavine, (4) salutaridine and salutaridinol. Salutaridinol-7-O-acetate shows a different fragmentation behavior because of the favored loss of acetic acid. Although most fragment ions occur in both ion trap and triple quad tandem mass spectra, some are exclusively seen in either type. For triple quad, quadrupole time-of-flight and FT-ICR MS/MS, the base peak of morphine results from an ion at m/z 165 that contains neither nitrogen nor oxygen. This ion is not found in ion trap MS/MS, but in subsequential MS3 and MS4.

  7. Challenges and recent advances in mass spectrometric imaging of neurotransmitters

    PubMed Central

    Gemperline, Erin; Chen, Bingming; Li, Lingjun

    2014-01-01

    Mass spectrometric imaging (MSI) is a powerful tool that grants the ability to investigate a broad mass range of molecules, from small molecules to large proteins, by creating detailed distribution maps of selected compounds. To date, MSI has demonstrated its versatility in the study of neurotransmitters and neuropeptides of different classes toward investigation of neurobiological functions and diseases. These studies have provided significant insight in neurobiology over the years and current technical advances are facilitating further improvements in this field. neurotransmitters, focusing specifically on the challenges and recent Herein, we advances of MSI of neurotransmitters. PMID:24568355

  8. Mass spectrometric thermodynamic studies of oxide systems and materials

    NASA Astrophysics Data System (ADS)

    Stolyarova, V. L.

    2016-01-01

    Progress in methods of synthesis of advanced materials as well as utilization of such materials at high temperatures requires information on the vaporization processes and thermodynamic properties of oxide systems. The optimal experimental method for these purposes is high-temperature mass spectrometry. This review summarizes and classifies experimental results obtained in mass spectrometric studies of the high-temperature thermodynamic properties of oxide systems and materials carried out in the last two decades. Published data on the vaporization processes and thermodynamic properties of oxide materials for high-temperature technologies are discussed from the standpoint of acid-base concept and model approaches including statistical thermodynamic methods. The bibliography includes 248 references.

  9. Outlier Detection for Mass Spectrometric Data.

    PubMed

    Cho, HyungJun; Eo, Soo-Heang

    2016-01-01

    Mass spectrometry data are often generated from various biological or chemical experiments. However, due to technical reasons, outlying observations are often obtained, some of which may be extreme. Identifying the causes of outlying observations is important in the analysis of replicated MS data because elaborate pre-processing is essential in order to obtain successful analyses with reliable results, and because manual outlier detection is a time-consuming pre-processing step. It is natural to measure the variability of observations using standard deviation or interquartile range calculations, and in this work, these criteria for identifying outliers are presented. However, the low replicability and the heterogeneity of variability are often obstacles to outlier detection. Therefore, quantile regression methods for identifying outliers with low replication are also presented. The procedures are illustrated with artificial and real examples, while a software program is introduced to demonstrate how to apply these procedures in the R environment system.

  10. Mass spectrometric studies of trimethylindium pyrolysis

    NASA Technical Reports Server (NTRS)

    Buchan, N. I.; Larsen, C. A.; Stringfellow, G. B.

    1988-01-01

    The kinetics of the pyrolysis of trimethylindium (TMIn) in He, D2, and H2 carriers was investigated using the atmospheric pressure flow-tube apparatus described by Larsen et al. (1987) and a time-of-flight mass spectrometer. The rate constant for the pyrolysis of TMIn in He was found to be comparable to that found by Jacko and Price (1964) for TMIn in toluene carrier (a radical scavenger), indicating that TMIn decomposes in He not by radical attack of methyl groups, but by homolytic fission. The decomposition of TMIn is enhanced in D2 and H2 carriers, where the principal products are CH3D and C2H6, and CH4 and C2H6, respectively, indicating that the reaction pathway in these carriers is different from those in He and toluene. The pyrolysis in H2 and D2 is attributed to a radical attack by H or D on TMIn. A reaction mechanism involving a short-lived hypervalent DTMIn species was proposed and was tested using numerical modeling techniques.

  11. Mass-spectrometric monitoring of the stress reaction during anesthesia

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.; Faizov, I. I.; Shchegolev, A. V.

    2013-10-01

    Clinical testing data for a mass-spectrometric method of estimating the patient's stress reaction to an injury done during anesthesia are presented. The essence of the method is monitoring the respiratory coefficient, which is defined as ratio N of the expiratory mass concentration of CO2 to the inspiratory mass concentration of O2 at each breathing cycle. For on-line monitoring of N, an electron ionization mass spectrometer connected to the breathing circuit of an inhalational anesthesia machine is used. Estimates of the anesthesia adequacy obtained with this method are compared with those obtained with the method that analyzes induced acoustic encephalographic potentials. It is shown that the method suggested is more sensitive to the level of the patient's stress reaction during anesthesia than the induced potential method.

  12. A high pressure modulated molecular beam mass spectrometric sampling system

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.; Miller, R. A.

    1977-01-01

    The current state of understanding of free-jet high pressure sampling is critically reviewed and modifications of certain theoretical and empirical considerations are presented. A high pressure, free-jet expansion, modulated molecular beam, mass spectrometric sampling apparatus was constructed and this apparatus is described in detail. Experimental studies have demonstrated that the apparatus can be used to sample high temperature systems at pressures up to one atmosphere. Condensible high temperature gaseous species have been routinely sampled and the mass spectrometric detector has provided direct identification of sampled species. System sensitivity is better than one tenth of a part per million. Experimental results obtained with argon and nitrogen beams are presented and compared to theoretical predictions. These results and the respective comparison are taken to indicate acceptable performance of the sampling apparatus. Results are also given for two groups of experiments related to hot corrosion studies. The formation of gaseous sodium sulfate in doped methane-oxygen flames was characterized and the oxidative vaporization of metals was studied in an atmospheric pressure flowing gas system to which gaseous salt partial pressures were added.

  13. Advances in Mass Spectrometric Tools for Probing Neuropeptides

    NASA Astrophysics Data System (ADS)

    Buchberger, Amanda; Yu, Qing; Li, Lingjun

    2015-07-01

    Neuropeptides are important mediators in the functionality of the brain and other neurological organs. Because neuropeptides exist in a wide range of concentrations, appropriate characterization methods are needed to provide dynamic, chemical, and spatial information. Mass spectrometry and compatible tools have been a popular choice in analyzing neuropeptides. There have been several advances and challenges, both of which are the focus of this review. Discussions range from sample collection to bioinformatic tools, although avenues such as quantitation and imaging are included. Further development of the presented methods for neuropeptidomic mass spectrometric analysis is inevitable, which will lead to a further understanding of the complex interplay of neuropeptides and other signaling molecules in the nervous system.

  14. Mass Spectrometric Analysis of Soot Particles: Combining Bulk and Single Particle Instrumentation

    NASA Astrophysics Data System (ADS)

    Sierau, B.; Mensah, A. A.; Corbin, J. C.

    2011-12-01

    Soot aerosols are of major interest in current atmospheric research in part because they absorb radiation and influence cloud formation and precipitation by acting as cloud condensation and ice nuclei. In order to predict the properties of atmospheric soot particles, a thorough understanding of their chemical composition and mixing state is of major importance. While freshly emitted soot is initially hydrophobic and externally mixed, it can become internally mixed by coagulating with other particles or by condensation of secondary species such as sulfate, ammonium, organics, nitrate and water. Via these mechanisms, a large fraction of BC is expected to be in an internally mixed state in the atmosphere. Additionally, the combustion process itself leads to a high variability in the chemical composition of the emitted soot particles, depending on the burnt fuel and the burning process. The Soot Particle Aerosol Mass Spectrometer (SP-AMS) is a new instrument especially suited for the chemical characterization of soot particles and their surface coatings. We report on experiments using the SP-AMS for the investigation of soot and black carbon particles produced under well-defined laboratory conditions. The focus of the study is put on a detailed characterization of the new SP-AMS instrument and its capabilities to detect and quantify the mass of the particle's soot core and eventually that of surface coatings. Different soot sources, e.g. particles produced by the miniCAST (Combustion Aerosol STandard) propane burner or aerosolized by an atomizer, are studied. The coating of aerosol particles is achieved by using a laminar flow tube in which secondary species can condense on their surface. The SP-AMS is characterized in conjunction with measurements from an Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) that is deployed in parallel. The ATOFMS is capable of sizing and analyzing aerosol particles individually, and gives insight into the mixing state of the analyzed

  15. Mass spectrometric profiling of flavonoid glycoconjugates possessing isomeric aglycones.

    PubMed

    Abrankó, László; Szilvássy, Blanka

    2015-01-01

    In fields such as food and nutrition science or plant physiology, interest in untargeted profiling of flavonoids continues to expand. The group of flavonoids encompasses several thousands of chemically distinguishable compounds, among which are a number of isobaric compounds with the same elemental composition. Thus, the mass spectrometric identification of these compounds is challenging, especially when reference standards are not available to support their identification. Many different types of isomers of flavonoid glycoconjugates are known, i.e. compounds that differ in their glycosylation position, glycan sequence or type of interglycosidic linkage. This work focuses on the mass spectrometric identification of flavonoid glycoconjugate isomers possessing the same glycan mass and differing only in their aglycone core. A non-targeted HPLC-ESI-MS/MS profiling method using a triple quadrupole MS is presented herein, which utilizes in-source fragmentation and a pseudo-MS(3) approach for the selective analysis of flavonoid glycoconjugates with isomeric/isobaric aglycones. A selective MRM-based identification of the in-source formed isobaric aglycone fragments was established. Additionally, utilizing the precursor scanning capability of the employed triple quadrupole instrument, the developed method enabled the determination of the molecular weight of the studied intact flavonoid glycoconjugate. The versatility of the method was proven with various types of flavonoid aglycones, i.e. anthocyanins, flavonols, flavones, flavanones and isoflavones, along with their representative glycoconjugates. The developed method was also successfully applied to a commercially available sour cherry sample, in which 16 different glycoconjugates of pelargonidin, genistein, cyanidin, kaempferol and quercetin could be tentatively identified, including a number of compounds containing isomeric/isobaric aglycones.

  16. Qualitative analysis of algal secretions with multiple mass spectrometric platforms.

    PubMed

    Kind, Tobias; Meissen, John K; Yang, Dawei; Nocito, Fernando; Vaniya, Arpana; Cheng, Yu-Shen; Vandergheynst, Jean S; Fiehn, Oliver

    2012-06-29

    Lipid secretions from algae pose a great opportunity for engineering biofueler feedstocks. The lipid exudates could be interesting from a process engineering perspective because lipids could be collected directly from the medium without harvesting and disrupting cells. We here report on the extracellular secretions of algal metabolites from the strain UTEX 2341 (Chlorella minutissima) into the culture medium. No detailed analysis of these lipid secretions has been performed to date. Using multiple mass spectrometric platforms, we observed around 1000 compounds and were able to annotate 50 lipids by means of liquid chromatography coupled to accurate mass quadrupole time-of-flight mass spectrometry (LC-QTOF), direct infusion with positive and negative electrospray ion trap mass spectrometry and gas chromatography coupled to mass spectrometry (GC-MS). These compounds were annotated by tandem mass spectral (MS/MS) database matching and retention time range filtering. We observed a series of triacylglycerols (TG), sulfoquinovosyldiacylglycerols (SQDG), phosphatidylinositols and phosphatidylglycerols, as well as betaine lipids diacylglyceryl-N,N,N-trimethylhomoserines (DGTS).

  17. Mass spectrometric searches for superheavy elements in terrestrial matter

    NASA Astrophysics Data System (ADS)

    Korschinek, Gunther; Kutschera, Walter

    2015-12-01

    Recent searches for traces of long-lived superheavy elements (SHEs) in terrestrial materials by mass spectrometric means are reviewed. Positive evidence for long-lived neutron-deficient Th isotopes in Th and Rg isotopes in Au, and a possible A = 292, Z ∼ 122 nuclide in Th was reported from experiments with Inductively Coupled Plasma Sector Field Mass Spectrometry (ICP-SF-MS). These findings were not confirmed with Accelerator Mass Spectrometry (AMS), with abundance limits lower by several orders of magnitude. In addition, the extensive AMS searches for 42 SHE nuclides (A = 288- 310) around the much discussed "island of stability" (Z = 114, N = 184) in natural Pt, Au, Pb, Bi materials are reviewed. Due to the flatness of the mass distribution and the relatively large bandwidth of the mass acceptance in AMS searches, an effectively much larger number of SHE nuclides was scanned in the respective materials. No positive evidence for the existence of long-lived SHEs (t1/2 >108 yr) with abundance limits of 10-12 to 10-16 was found.

  18. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    PubMed

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  19. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    PubMed

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-07

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.

  20. Mass Spectrometric Imaging Using Laser Ablation and Solvent Capture by Aspiration (LASCA)

    NASA Astrophysics Data System (ADS)

    Brauer, Jonathan I.; Beech, Iwona B.; Sunner, Jan

    2015-09-01

    A novel interface for ambient, laser ablation-based mass spectrometric imaging (MSI) referred to as laser ablation and solvent capture by aspiration (LASCA) is presented and its performance demonstrated using selected, unaltered biological materials. LASCA employs a pulsed 2.94 μm laser beam for specimen ablation. Ablated materials in the laser plumes are collected on a hanging solvent droplet with electric field-enhanced trapping, followed by aspiration of droplets and remaining plume material in the form of a coarse aerosol into a collection capillary. The gas and liquid phases are subsequently separated in a 10 μL-volume separatory funnel, and the solution is analyzed with electrospray ionization in a high mass resolution Q-ToF mass spectrometer. The LASCA system separates the sampling and ionization steps in MSI and combines high efficiencies of laser plume sampling and of electrospray ionization (ESI) with high mass resolution MS. Up to 2000 different compounds are detected from a single ablation spot (pixel). Using the LASCA platform, rapid (6 s per pixel), high sensitivity, high mass-resolution ambient imaging of "as-received" biological material is achieved routinely and reproducibly.

  1. Determination of aerosol ammonium using an aerodyne aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Toohey, D. W.; Worsnop, D. R.

    2003-04-01

    The chemical composition of fine aerosols is a significant issue both because it influences the chemical and radiative properties of the aerosols, which in turn impact the regional and global climate and human health, and because it is difficult to measure accurately. The Aerosol Mass Spectrometer (AMS) developed by Aerodyne Research measures both chemical composition and aerodynamic size of submicron aerosols quantitatively. However, the measurement of aerosol ammonium is more difficult than that of the other major inorganic species, nitrate and sulfate, because of interferences in the mass spectrum from air and water. This presentation will describe the successful procedure developed for dealing with these interferences and accurately determining the ammonium mass. In addition, the application of this procedure to aerosols from a range of ambient conditions will be demonstrated using data from several field studies.

  2. DEVELOPMENT OF AN ELECTROSPRAY MASS SPECTROMETRIC METHOD FOR DETERMINING PERCHLORATE IN FERTILIZERS

    EPA Science Inventory

    An electrospray mass spectrometric method has been developed for application to agricultural and horticultural fertilizers to determine perchlorate. After fertilizers are leached or dissolved in water, the method relies on the formation of stable ion pair complex of the perchlor...

  3. Status of mass spectrometric radiocarbon detection at ETHZ

    NASA Astrophysics Data System (ADS)

    Seiler, Martin; Maxeiner, Sascha; Wacker, Lukas; Synal, Hans-Arno

    2015-10-01

    A prototype of a mass spectrometric radiocarbon detection instrument without accelerator stage was built for the first time and set into operation at ETH Zurich. The system is designed as an experimental platform to optimize performance of 14C detection at low ion energies and to study the most relevant processes that may limit system performance. The optimized stripper unit incorporates differential pumping to maintain a low gas outflow and a revised tube design to better match the phase space volume of the ion beam at low energies. The system is fully operational and has demonstrated true radiocarbon dating capabilities. The overall beam transmission through the stripper tube is about 40% for the 1+ charge state. Radiocarbon analyses with an overall precision of 0.6% were obtained on a single sample under regular measurement conditions. By analyzing multiple targets of the same sample material an uncertainty level of 0.3% has been reached. The background level corresponds to a radiocarbon age of 40,000 years.

  4. Oxidative Ionization Under Certain Negative-Ion Mass Spectrometric Conditions

    NASA Astrophysics Data System (ADS)

    Hassan, Isra; Pavlov, Julius; Errabelli, Ramu; Attygalle, Athula B.

    2017-02-01

    1,4-Hydroquinone and several other phenolic compounds generate (M - 2) -• radical-anions, rather than deprotonated molecules, under certain negative-ion mass spectrometric conditions. In fact, spectra generated under helium-plasma ionization (HePI) conditions from 1,4-hydroquinone and 1,4-benzoquinone (by electron capture) were practically indistinguishable. Because this process involves a net loss of H• and H+, it can be termed oxidative ionization. The superoxide radical-anion (O2 -•), known to be present in many atmospheric-pressure plasma ion sources operated in the negative mode, plays a critical role in the oxidative ionization process. The presence of a small peak at m/z 142 in the spectrum of 1,4-hydroquinone, but not in that of 1,4-benzoquinone, indicated that the initial step in the oxidative ionization process is the formation of an O2 -• adduct. On the other hand, under bona fide electrospray ionization (ESI) conditions, 1,4-hydroquinone generates predominantly an (M - 1) - ion. It is known that at sufficiently high capillary voltages, corona discharges begin to occur even in an ESI source. At lower ESI capillary voltages, deprotonation predominates; as the capillary voltage is raised, the abundance of O2 -• present in the plasma increases, and the source in turn increasingly behaves as a composite ESI/APCI source. While maintaining post-ionization ion activation to a minimum (to prevent fragmentation), and monitoring the relative intensities of the m/z 109 (due to deprotonation) and 108 (oxidative ionization) peaks recorded from 1,4-hydroquinone, a semiquantitative estimation of the APCI contribution to the overall ion-generation process can be obtained.

  5. Oxidative Ionization Under Certain Negative-Ion Mass Spectrometric Conditions.

    PubMed

    Hassan, Isra; Pavlov, Julius; Errabelli, Ramu; Attygalle, Athula B

    2017-02-01

    1,4-Hydroquinone and several other phenolic compounds generate (M - 2) (-•) radical-anions, rather than deprotonated molecules, under certain negative-ion mass spectrometric conditions. In fact, spectra generated under helium-plasma ionization (HePI) conditions from 1,4-hydroquinone and 1,4-benzoquinone (by electron capture) were practically indistinguishable. Because this process involves a net loss of H(•) and H(+), it can be termed oxidative ionization. The superoxide radical-anion (O2(-•)), known to be present in many atmospheric-pressure plasma ion sources operated in the negative mode, plays a critical role in the oxidative ionization process. The presence of a small peak at m/z 142 in the spectrum of 1,4-hydroquinone, but not in that of 1,4-benzoquinone, indicated that the initial step in the oxidative ionization process is the formation of an O2(-•) adduct. On the other hand, under bona fide electrospray ionization (ESI) conditions, 1,4-hydroquinone generates predominantly an (M - 1) (-) ion. It is known that at sufficiently high capillary voltages, corona discharges begin to occur even in an ESI source. At lower ESI capillary voltages, deprotonation predominates; as the capillary voltage is raised, the abundance of O2(-•) present in the plasma increases, and the source in turn increasingly behaves as a composite ESI/APCI source. While maintaining post-ionization ion activation to a minimum (to prevent fragmentation), and monitoring the relative intensities of the m/z 109 (due to deprotonation) and 108 (oxidative ionization) peaks recorded from 1,4-hydroquinone, a semiquantitative estimation of the APCI contribution to the overall ion-generation process can be obtained. Graphical Abstract ᅟ.

  6. Mass spectrometric characterization of methylaluminoxane-activated metallocene complexes.

    PubMed

    Trefz, Tyler K; Henderson, Matthew A; Linnolahti, Mikko; Collins, Scott; McIndoe, J Scott

    2015-02-09

    Electrospray-ionization mass spectrometric studies of poly(methylaluminoxane) (MAO) in the presence of [Cp2 ZrMe2 ], [Cp2 ZrMe(Cl)], and [Cp2 ZrCl2 ] in fluorobenzene (PhF) solution are reported. The results demonstrate that alkylation and ionization are separate events that occur at competitive rates in a polar solvent. Furthermore, there are significant differences in ion-pair speciation that result from the use of metallocene dichloride complexes in comparison to alkylated precursors at otherwise identical Al/Zr ratios. Finally, the counter anions that form are dependent on the choice of precursor and Al/Zr ratio; halogenated aluminoxane anions [(MeAlO)x (Me3 Al)y-z (Me2 AlCl)z Me](-) (z=1, 2, 3…︁) are observed using metal chloride complexes and under some conditions may predominate over their non-halogenated precursors [(MeAlO)x (Me3 Al)y Me](-) . Specifically, this halogenation process appears selective for the anions that form in comparison to the neutral components of MAO. Only at very high Al/Zr ratios is the same "native" anion distribution observed when using [Cp2 ZrCl2 ] when compared with [Cp2 ZrMe2 ]. Together, the results suggest that the need for a large excess of MAO when using metallocene dichloride complexes is a reflection of competitive alkylation vs. ionization, the persistence of unreactive, homodinuclear ion pairs in the case of [Cp2 ZrCl2 ], as well as a change in ion pairing resulting from modification of the anions formed at lower Al/Zr ratios. Models for neutral precursors and anions are examined computationally.

  7. Measuring masses of large biomolecules and bioparticles using mass spectrometric techniques.

    PubMed

    Peng, Wen-Ping; Chou, Szu-Wei; Patil, Avinash A

    2014-07-21

    Large biomolecules and bioparticles play a vital role in biology, chemistry, biomedical science and physics. Mass is a critical parameter for the characterization of large biomolecules and bioparticles. To achieve mass analysis, choosing a suitable ion source is the first step and the instruments for detecting ions, mass analyzers and detectors should also be considered. Abundant mass spectrometric techniques have been proposed to determine the masses of large biomolecules and bioparticles and these techniques can be divided into two categories. The first category measures the mass (or size) of intact particles, including single particle quadrupole ion trap mass spectrometry, cell mass spectrometry, charge detection mass spectrometry and differential mobility mass analysis; the second category aims to measure the mass and tandem mass of biomolecular ions, including quadrupole ion trap mass spectrometry, time-of-flight mass spectrometry, quadrupole orthogonal time-of-flight mass spectrometry and orbitrap mass spectrometry. Moreover, algorithms for the mass and stoichiometry assignment of electrospray mass spectra are developed to obtain accurate structure information and subunit combinations.

  8. Contribution of methane to aerosol carbon mass

    NASA Astrophysics Data System (ADS)

    Bianchi, F.; Barmet, P.; Stirnweis, L.; El Haddad, I.; Platt, S. M.; Saurer, M.; Lötscher, C.; Siegwolf, R.; Bigi, A.; Hoyle, C. R.; DeCarlo, P. F.; Slowik, J. G.; Prévôt, A. S. H.; Baltensperger, U.; Dommen, J.

    2016-09-01

    Small volatile organic compounds (VOC) such as methane (CH4) have long been considered non-relevant to aerosol formation due to the high volatility of their oxidation products. However, even low aerosol yields from CH4, the most abundant VOC in the atmosphere, would contribute significantly to the total particulate carbon budget. In this study, organic aerosol (OA) mass yields from CH4 oxidation were evaluated at the Paul Scherrer Institute (PSI) smog chamber in the presence of inorganic and organic seed aerosols. Using labeled 13C methane, we could detect its oxidation products in the aerosol phase, with yields up to 0.09

  9. Modular Mass Spectrometric Tool for Analysis of Composition and Phosphorylation of Protein Complexes

    PubMed Central

    Blethrow, Justin D.; Tang, Chao; Deng, Changhui; Krutchinsky, Andrew N.

    2007-01-01

    The combination of high accuracy, sensitivity and speed of single and multiple-stage mass spectrometric analyses enables the collection of comprehensive sets of data containing detailed information about complex biological samples. To achieve these properties, we combined two high-performance matrix-assisted laser desorption ionization mass analyzers in one modular mass spectrometric tool, and applied this tool for dissecting the composition and post-translational modifications of protein complexes. As an example of this approach, we here present studies of the Saccharomyces cerevisiae anaphase-promoting complexes (APC) and elucidation of phosphorylation sites on its components. In general, the modular concept we describe could be useful for assembling mass spectrometers operating with both matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) ion sources into powerful mass spectrometric tools for the comprehensive analysis of complex biological samples. PMID:17406682

  10. Analyses of Heavy Metal Contents in the Bulk Atmospheric Aerosols Simultaneously Collected at Okinawa Archipelago, Japan by Using X-ray fluorescence spectrometric method (XRF)

    NASA Astrophysics Data System (ADS)

    Oshiro, Y.; ITOH, A.; Azechi, S.; Somada, Y.; Handa, D.; Miyagi, Y.; Arakaki, T.; Tanahara, A.

    2012-12-01

    We studied heavy metal contents of bulk atmospheric aerosols using an X-ray fluorescence spectrometric method (XRF). The XRF method enables us to analyze heavy metal contents in the bulk aerosols rapidly without any chemical pretreatments. We used an energy dispersive X-ray fluorescence spectrometer that is compact and portable. We prepared several different amounts of standard reference materials (referred to "SRM", NIES No.28 of Japanese National Institute of Environmental Studies) on quartz filters for calibration curves in two different methods; 1) water-insoluble materials were collected after dispersing SRM in pure water and filtered with the quartz filters ("wet method"), and 2) SRM was dispersed in air in the plastic container and the aerosols were collected by using the low-volume air sampler ("dry method"). Good linear relationships between X-ray intensity and amount of aerosols on the filter were seen in the following 9 metals; Al, K, Ti, V, Fe, Ni, Rb, Ba, and Pb (with wet method) and 12 metals; K, Ti, Fe, Ni, Rb, Ba, Pb, Sr, Ca, Mn, Zn, and Cu (with dry method). Furthermore, we evaluated quantitative responses of XRF method by comparing with the metal contents determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after acid-digestion. We then used XRF method to determine heavy metal contents in authentic atmospheric aerosols collected in Okinawa islands, Japan. We simultaneously collected bulk aerosol samples by using identical high-volume air samplers at 3 islands; Cape Hedo Atmospheric Aerosol Monitoring Station (CHAAMS, Okinawa island), Kume island (ca. 160 km south-west of CHAAMS), and Minami-Daitou island (ca. 320 km south-east of CHAAMS). We report and discuss spatial and temporal distribution of heavy metals determined by the XRF method in the bulk atmospheric aerosols collected at the three islands during June 2008 to June 2010, and for CHAAMS during June 2008 to October 2012.

  11. Mass spectrometric monitoring of interfacial photoelectron transfer and imaging of active crystalline facets of semiconductors

    NASA Astrophysics Data System (ADS)

    Zhong, Hongying; Zhang, Juan; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Li, Rui; Chen, Disong; Wang, Peng; Yuan, Zhiwei

    2017-02-01

    Monitoring of interfacial electron transfer (ET) in situ is important to understand the ET mechanism and designing efficient photocatalysts. We describe herein a mass spectrometric approach to investigate the ultrafast transfer of photoelectrons that are generated by ultraviolet irradiation on surfaces of semiconductor nanoparticles or crystalline facets. The mass spectrometric approach can not only untargetedly detect various intermediates but also monitor their reactivity through associative or dissociative photoelectron capture dissociation, as well as electron detachment dissociation of adsorbed molecules. Proton-coupled electron transfer and proton-uncoupled electron transfer with radical initiated polymerization or hydroxyl radical abstraction have been unambiguously demonstrated with the mass spectrometric approach. Active crystalline facets of titanium dioxide for photocatalytic degradation of juglone and organochlorine dichlorodiphenyltrichloroethane are visualized with mass spectrometry imaging based on ion scanning and spectral reconstruction. This work provides a new technique for studying photo-electric properties of various materials.

  12. Mass spectrometric monitoring of interfacial photoelectron transfer and imaging of active crystalline facets of semiconductors

    PubMed Central

    Zhong, Hongying; Zhang, Juan; Tang, Xuemei; Zhang, Wenyang; Jiang, Ruowei; Li, Rui; Chen, Disong; Wang, Peng; Yuan, Zhiwei

    2017-01-01

    Monitoring of interfacial electron transfer (ET) in situ is important to understand the ET mechanism and designing efficient photocatalysts. We describe herein a mass spectrometric approach to investigate the ultrafast transfer of photoelectrons that are generated by ultraviolet irradiation on surfaces of semiconductor nanoparticles or crystalline facets. The mass spectrometric approach can not only untargetedly detect various intermediates but also monitor their reactivity through associative or dissociative photoelectron capture dissociation, as well as electron detachment dissociation of adsorbed molecules. Proton-coupled electron transfer and proton-uncoupled electron transfer with radical initiated polymerization or hydroxyl radical abstraction have been unambiguously demonstrated with the mass spectrometric approach. Active crystalline facets of titanium dioxide for photocatalytic degradation of juglone and organochlorine dichlorodiphenyltrichloroethane are visualized with mass spectrometry imaging based on ion scanning and spectral reconstruction. This work provides a new technique for studying photo-electric properties of various materials. PMID:28224986

  13. Mass Spectrometric Characteristics of Prenylated Indole Derivatives from Marine-Derived Penicillium sp. NH-SL.

    PubMed

    Ding, Hui; Ding, Wanjing; Ma, Zhongjun

    2017-03-22

    Two prenylated indole alkaloids were isolated from the ethyl acetate extracts of a marine-derived fungus Penicillium sp. NH-SL and one of them exhibited potent cytotoxic activity against mouse hepa 1c1c7 cells. In order to detect other bioactive analogs, we used liquid chromatogram tandem mass spectrometry (LC-MS/MS) to analyze the mass spectrometric characteristics of the isolated compounds as well as the crude extracts. As a result, three other analogs were detected, and their structures were deduced according to the similar fragmentation patterns. This is the first systematic report on the mass spectrometric characteristics of prenylated indole derivatives.

  14. Mass Spectrometric Characteristics of Prenylated Indole Derivatives from Marine-Derived Penicillium sp. NH-SL

    PubMed Central

    Ding, Hui; Ding, Wanjing; Ma, Zhongjun

    2017-01-01

    Two prenylated indole alkaloids were isolated from the ethyl acetate extracts of a marine-derived fungus Penicillium sp. NH-SL and one of them exhibited potent cytotoxic activity against mouse hepa 1c1c7 cells. In order to detect other bioactive analogs, we used liquid chromatogram tandem mass spectrometry (LC-MS/MS) to analyze the mass spectrometric characteristics of the isolated compounds as well as the crude extracts. As a result, three other analogs were detected, and their structures were deduced according to the similar fragmentation patterns. This is the first systematic report on the mass spectrometric characteristics of prenylated indole derivatives. PMID:28327529

  15. Characterization of Heavy Metal Contents in the Bulk Atmospheric Aerosols Simultaneously Collected at Three Islands in Okinawa, Japan by X-ray fluorescence spectrometric method (XRF)

    NASA Astrophysics Data System (ADS)

    Oshiro, Y.; ITOH, A.; Azechi, S.; Somada, Y.; Handa, D.; Miyagi, Y.; Arakaki, T.; Tanahara, A.

    2011-12-01

    We studied heavy metal contents of atmospheric aerosols using an X-ray fluorescence spectrometric method (XRF). The XRF method enables us to analyze heavy metal contents of bulk aerosols rapidly without any chemical pretreatments. We used an energy dispersive X-ray fluorescence spectrometer that is compact and portable. We prepared several different amounts of standard reference materials (NIES No.28) of Japanese National Institute of Environmental Studies on quartz filters for calibration curves. Then, we evaluated quantitative responses of XRF method by comparing with the metal contents determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS) after acid-digestion. Good linear relationships between X-ray intensity and amount of aerosol on filter were seen in the following 10 metals; Al, K, Ti, V, Fe, Ni, Rb, Ba, Pb and As. We then used XRF method to determine heavy metal contents in authentic atmospheric aerosols collected in Okinawa islands, Japan. Okinawa islands, consisting of many small islands, are situated east of Asian continent, and its location in Asian is well suited for studying long-range transport of air pollutants. Also, in Okinawa islands, maritime air mass prevails during summer, while Asian continental air mass dominates during fall, winter, and spring. The maritime air mass data can be seen as background clean air and can be compared with continental air mass which has been affected by anthropogenic activities such as industries and automobiles. Therefore, Okinawa region is suitable area for studying impacts of air pollutants from East Asia. We simultaneously collected bulk aerosol samples by using identical high-volume air samplers at 3 islands; Cape Hedo Atmospheric Aerosol Monitoring Station (CHAAMS, Okinawa island), Kume island (ca. 160 km south-west of CHAAMS), and Minami-Daitou island (ca. 320 km south-east of CHAAMS). We report and discuss spatial and temporal distribution of heavy metals

  16. Differentiating organic from conventional peppermints using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High performance liquid chromatography (HPLC) and flow-injection mass spectrometric (FIMS) fingerprinting techniques were tested for their potential in differentiating organic and conventional peppermint samples. Ten organic and ten conventional peppermint samples were examined using HPLC-UV and FI...

  17. Systematic studies of the mass spectrometric properties of alkaline earth metal cationized amino acids and peptides

    NASA Astrophysics Data System (ADS)

    Küjckelmann, Ulrich; Müller, Dietrich; Weber, Carsten

    1997-07-01

    The results of a systematic study of the gas phase interactions of α-amino acids and peptides (4-15 amino acids) with alkaline earth metals, observed with mass spectrometric techniques, are presented. Furthermore, a model for the cationization with calcium at the C-terminal amino acid arginine in rotaviral polypeptides is presented.

  18. Mass spectrometric methods for the direct elemental and isotopic analysis of solid material

    NASA Astrophysics Data System (ADS)

    Ganeev, A. A.; Gubal, A. R.; Potapov, S. V.; Agafonova, N. N.; Nemets, V. M.

    2016-04-01

    Methods for the direct analysis of solids have a number of undeniable advantages over the methods that require preliminary dissolution of samples. High sensitivity and selectivity make the direct mass spectrometric techniques the most in-demand. The review concerns spark source mass spectrometry, laser ionization mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, secondary ion mass spectrometry, secondary neutral mass spectrometry and glow discharge mass spectrometry. Basic principles, analytical characteristics and trends in the development of these techniques are discussed. Particular attention is given to applications of the techniques as well as to their competitive advantages and drawbacks. The bibliography includes 123 references.

  19. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    PubMed

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  20. Synchronised Aerosol Mass Spectrometer Measurements across Europe

    NASA Astrophysics Data System (ADS)

    Nemitz, Eiko

    2010-05-01

    Up to twelve Aerodyne Aerosol Mass Spectrometers (AMSs) were operated simultaneously at rural and background stations (EMEP and EUSAAR sites) across Europe. Measurements took place during three intensive periods, in collaboration between the European EUCAARI IP and the EMEP monitoring activities under the UNECE Convention for Long-Range Transboundary Air Pollution (CLRTAP) during three contrasting months (May 2008, Sep/Oct 2008, Feb/Mar 2009). These measurements were conducted, analysed and quality controlled carefully using a unified protocol, providing the largest spatial database of aerosol chemical composition measured with a unified online technique to date, and a unique snapshots of the European non-refractory submicron aerosol climatology. As campaign averages over all active monitoring sites, organics represent 28 to 43%, sulphate 18 to 25%, ammonium 13 to 15% and nitrate 15 to 36% of the resolved aerosol mass, with the highest relative nitrate contribution during the Feb/Mar campaign. The measurements demonstrate that in NW Europe (e.g. Ireland, UK, The Netherlands, Germany, Switzerland) the regional submicron aerosol tends to be neutralised and here nitrates make a major contribution to the aerosol mass. By contrast, periods with low nitrate and acidic aerosol were observed at sites in S and E Europe (e.g. Greece, Finland), presumably due to a combination of larger SO2 point sources in Easter Europe, smaller local NH3 sources and, in the case of Greece, higher temperatures. While at the more marine and remote sites (Ireland, Scotland, Finland) nitrate concentrations were dominated by episodic transport phenomena, at continental sites (Switzerland, Germany, Hungary) nitrate followed a clear diurnal cycle, reflecting the thermodynamic behaviour of ammonium nitrate. The datasets clearly shows spatially co-ordinated, large-scale pollution episodes of organics, sulphate and nitrate, the latter being most pronounced during the Feb/Mar campaign. At selected

  1. Mass spectrometric analysis of the volatiles released by heating or crushing rocks

    NASA Technical Reports Server (NTRS)

    Barker, C.; Sommer, M. A.

    1973-01-01

    Vacuum extraction with subsequent mass spectrometric analysis of evolved volatiles was selected as the analytical procedure. The high-vacuum gas-handling system was constructed of stainless steel. The system was completely free from mercury, grease, or volatile organic materials. The furnace for heating the samples is discussed together with the high-vacuum crusher, the mass spectrometer, and approaches for water determination. The analytical procedure is considered, giving attention to the extraction of volatiles, adsorption studies, and the analysis of volatiles.

  2. 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.

  3. [Mass spectrometric analysis of polycyclic aromatic hydrocarbons adducted to DNA]. Final report

    SciTech Connect

    Barofsky, D.F.

    1992-12-31

    Studies described herein sought and to synthesize PAH-adducted residues of DNA to serve as models for carrying out the mass spectrometric studies; to construct and test a high performance, pulsed ion bombardment, time-of-flight (TOF) mass spectrometer; to initiate an investigation of the efficacy of using thin wire sample holders to increase sensitivity and focused ion beam bombardment to increase ion yield and ion transmission; and to initiate an investigation of sensitivity enhancing matrices for PAH-adducted DNA.

  4. Electrospray ionization mass spectrometric characterization of acrylamide adducts to hemoglobin

    SciTech Connect

    Springer, D.L.; Goheen, S.C.; Edmonds, C.G. ); Bull, R.J.; Sylvester, D.M. )

    1993-01-01

    The most common procedure to identify hemoglobin adducts has been to cleave the adducts from the protein and characterize the adducting species, by, for example, derivatization and gas chromatography/mass spectrometry. To extend these approaches we used electrospray ionization mass spectrometry (ESI-MS) to characterize adducted hemoglobin. For this we incubated [[sup 14]C]acrylamide with the purified human hemoglobin (type A[sub 0]) under conditions that yielded high adduct levels. When the hemoglobin was separated by reversed-phase high-performance liquid chromatography (HPLC), 65% of the radioactivity copurified with the [beta]-subunit. Three adducted species were prominent in the ESI mass spectrum of the intact [beta]-subunit, indicating acrylamide adduction (i.e., mass increase of 71 Da) and two addition unidentified moieties with mass increments of 102 and 135 Da. Endoproteinase Glu-C digestion of the adducted [beta]-subunit resulted in a peptide mixture that, upon reversed-phase HPLC separation, provided several radiolabeled peptides. Using ESI-MS we identified these as the V[sub 91-101] and V[sub 102-122] peptides that represent the cysteine-containing peptides of the [beta]-subunit. These results provide definitive information on acrylamide-modified human hemoglobin and demonstrate that ESI-MS provides valuable structure information on chemically adducted proteins. 30 refs., 9 figs., 3 tabs.

  5. Mass Spectrometric Approaches to Detecting and Quantifying Prions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Until recently, the use of mass spectrometry has been limited to identifying covalent posttranslational modifications of PrPSc and PrPC. These efforts support the hypothesis that PrPC and PrPSc possess identical covalent posttranslational modifications. Technical advances in instrumentation now all...

  6. Mass Spectrometric Monitoring of Animal Feed for BSE Spread

    ERIC Educational Resources Information Center

    King, Angela G.

    2004-01-01

    The researchers in London have developed an emerging technology that utilizes mass spectrometry to detect processed animal protein (PAP) in animal feed. The amount of animal protein in the feed can be determined by the ratio of the hydrolyzed gelatine signal at m/z 1044 to an internal standard signal at m/z 556.

  7. Mass spectrometric analysis of protein–ligand interactions

    PubMed Central

    Ishii, Kentaro; Noda, Masanori; Uchiyama, Susumu

    2016-01-01

    The interactions of small molecules with proteins (protein–ligand interactions) mediate various biological phenomena including signal transduction and protein transcription and translation. Synthetic compounds such as drugs can also bind to target proteins, leading to the inhibition of protein–ligand interactions. These interactions typically accompany association–dissociation equilibrium according to the free energy difference between free and bound states; therefore, the quantitative biophysical analysis of the interactions, which uncovers the stoichiometry and dissociation constant, is important for understanding biological reactions as well as for rational drug development. Mass spectrometry (MS) has been used to determine the precise molecular masses of molecules. Recent advancements in MS enable us to determine the molecular masses of protein–ligand complexes without disrupting the non-covalent interactions through the gentle desolvation of the complexes by increasing the vacuum pressure of a chamber in a mass spectrometer. This method is called MS under non-denaturing conditions or native MS and allows the unambiguous determination of protein–ligand interactions. Under a few assumptions, MS has also been applied to determine the dissociation constants for protein–ligand interactions. The structural information of a protein–ligand interaction, such as the location of the interaction and conformational change in a protein, can also be analyzed using hydrogen/deuterium exchange MS. In this paper, we briefly describe the history, principle, and recent applications of MS for the study of protein–ligand interactions. PMID:27924262

  8. Mass spectrometric studies on the interaction of cisplatin and insulin.

    PubMed

    Li, Jing; Yue, Lei; Liu, Yaqin; Yin, Xinchi; Yin, Qi; Pan, Yuanjiang; Yang, Lirong

    2016-04-01

    The interaction of antitumor drug, cisplatin (cis-[PtCl2(NH3)2], CDDP) with insulin from porcine pancreas has been investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and high resolution hybrid ion trap/time-of-flight mass spectrometry (MALIDI-TOF/TOF-MS and ESI-IT/TOF MS). The MALDI-TOF/TOF-MS results demonstrated that the presence of cisplatin complex resulted in the reduction of the disulfide bond in porcine pancreas after the incubations of the two substances were performed in vitro. It indicated that the presence of cisplatin would destroy the native configuration of insulin, which may lead to the inactivation of insulin. High resolution mass values and the characteristic isotopic pattern of the platinated insulin ions allowed the analysis of platinated mono-, di- and triadducts of cisplatin and insulin in the incubations under different conditions. The laser-induced dissociation of the monoadduct obtained in MALDI source was carried out and one platinum was found to bind to insulin B chain was determined. The platinum binding sites were further identified to be the N terminus (B chain), cysteine 7 (B chain) and cysteine 19 (B chain) residues by electrospray ionization tandem mass spectrometry. The identification of the interaction between insulin and cisplatin broadens the horizon of the knowledge in the interaction of the proteins and metallodrugs.

  9. Extending the frontiers of mass spectrometric instrumentation and methods

    SciTech Connect

    Schieffer, Gregg Martin

    2010-01-01

    The focus of this dissertation is two-fold: developing novel analysis methods using mass spectrometry and the implementation and characterization of a novel ion mobility mass spectrometry instrumentation. The novel mass spectrometry combines ion trap for ion/ion reactions coupled to an ion mobility cell. The long term goal of this instrumentation is to use ion/ion reactions to probe the structure of gas phase biomolecule ions. The three ion source - ion trap - ion mobility - qTOF mass spectrometer (IT - IM - TOF MS) instrument is described. The analysis of the degradation products in coal (Chapter 2) and the imaging plant metabolites (Appendix III) fall under the methods development category. These projects use existing commercial instrumentation (JEOL AccuTOF MS and Thermo Finnigan LCQ IT, respectively) for the mass analysis of the degraded coal products and the plant metabolites, respectively. The coal degradation paper discusses the use of the DART ion source for fast and easy sample analysis. The sample preparation consisted of a simple 50 fold dilution of the soluble coal products in water and placing the liquid in front of the heated gas stream. This is the first time the DART ion source has been used for analysis of coal. Steven Raders under the guidance of John Verkade came up with the coal degradation projects. Raders performed the coal degradation reactions, worked up the products, and sent them to me. Gregg Schieffer developed the method and wrote the paper demonstrating the use of the DART ion source for the fast and easy sample analysis. The plant metabolite imaging project extends the use of colloidal graphite as a sample coating for atmospheric pressure LDI. DC Perdian and I closely worked together to make this project work. Perdian focused on building the LDI setup whereas Schieffer focused on the MSn analysis of the metabolites. Both Perdian and I took the data featured in the paper. Perdian was the primary writer of the paper and used it as a

  10. A mass spectrometric analysis of {gamma}-GPS films

    SciTech Connect

    Dillingham, R.G.; Boerio, F.J.; Bertelsen, C.; Savina, M.R.; Lykke, K.R.; Calaway, W.F.

    1996-06-01

    {gamma}-glycidoxypropyltrimethoxysilane ({gamma}-GPS) is used for pre-treatment of grit-blasted aluminum before adhesive bonding. This paper discusses analysis of non-reflective grit-blasted surfaces using mass spectrometry of species that were either sputtered off using an ion beam or thermally desorbed as neutrals using a pulsed laser and then post-ionized using a secondary laser. Results show that fragmentation is excessive and structural information is difficult to obtain from the spectra.

  11. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Mauersberger, K.

    1993-01-01

    The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

  12. QUANTITATIVE MASS SPECTROMETRIC ANALYSIS OF GLYCOPROTEINS COMBINED WITH ENRICHMENT METHODS

    PubMed Central

    Ahn, Yeong Hee; Kim, Jin Young; Yoo, Jong Shin

    2015-01-01

    Mass spectrometry (MS) has been a core technology for high sensitive and high-throughput analysis of the enriched glycoproteome in aspects of quantitative assays as well as qualitative profiling of glycoproteins. Because it has been widely recognized that aberrant glycosylation in a glycoprotein may involve in progression of a certain disease, the development of efficient analysis tool for the aberrant glycoproteins is very important for deep understanding about pathological function of the glycoprotein and new biomarker development. This review first describes the protein glycosylation-targeting enrichment technologies mainly employing solid-phase extraction methods such as hydrizide-capturing, lectin-specific capturing, and affinity separation techniques based on porous graphitized carbon, hydrophilic interaction chromatography, or immobilized boronic acid. Second, MS-based quantitative analysis strategies coupled with the protein glycosylation-targeting enrichment technologies, by using a label-free MS, stable isotope-labeling, or targeted multiple reaction monitoring (MRM) MS, are summarized with recent published studies. © 2014 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Rapid Commun. Mass Spec Rev 34:148–165, 2015. PMID:24889823

  13. Comparison of mass spectrometric techniques for generating molecular weight information on a class of ethoxylated oligomers.

    PubMed

    Parees, D M; Hanton, S D; Clark, P A; Willcox, D A

    1998-04-01

    The results of fast atom bombardment (FAB), time-of-flight secondary ion mass spectrometry (ToF-SIMS), matrix-assisted laser desorption/ionization (MALD/I), electrospray ionization (ESI), and field desorption (FD) analyses of ethoxylated oligomers of 2,4,7,9-tetramethyl-5-decyne-4,7-diol (Surfynol(®) 104) were compared.Each of these desorption mass spectrometry (MS) techniques can produce spectra of unfragmented cationized oligomers. From the observed ion series we calculate average molecular weight information. We have compared the results of mass spectrometric analyses of a series of ethoxylated Surfynol surfactants. Our data indicate that FAB, ToF-SIMS, MALDI/I, and ESI produce similar results for the lower molecular weight species, but that as the average molecular weight increases FAB and SIMS produce slightly lower results than MALD/I and FD. This could be due to increased fragmentation. ESI produced a result similar to FAB and SIMS for the highest average molecular weight material. Further experiments compare the mass spectral results with gas chromatographic quantitative data. Although gas chromatography is not expected to accurately analyze the higher mass oligomers, we observe significant differences in intensities of the short-chain oligomers (especially the 0- and 1-mers) when compared to the desorption mass spectrometer results. These differences may reflect poor cationization efficiency for very short oligomer chains in the mass spectrometric analyses.

  14. Secondary Ion Mass Spectrometry of Environmental Aerosols

    SciTech Connect

    Gaspar, Daniel J.; Cliff, John B.

    2010-08-01

    Atmospheric particles influence many aspects of climate, air quality and human health. Understanding the composition, chemistry and behavior of atmospheric aerosols is a key remaining challenge in improving climate models. Furthermore, particles may be traced back to a particular source based on composition, stable isotope ratios, or the presence of particular surface chemistries. Finally, the characterization of atmospheric particles in the workplace plays an important role in understanding the potential for exposure and environmental and human health effects to engineered and natural nanoscale particles. Secondary ion mass spectrometry (SIMS) is a useful tool in determining any of several aspects of the structure, composition and chemistry of these particles. Often used in conjunction with other surface analysis and electron microscopy methods, SIMS has been used to determine or confirm reactions on and in particles, the presence of particular organic species on the surface of atmospheric aerosols and several other interesting and relevant findings. Various versions of SIMS instruments – dynamic SIMS, time of flight secondary ion mass spectrometry or TOF-SIMS, nanoSIMS – have been used to determine specific aspects of aerosol structure and chemistry. This article describes the strengths of each type of SIMS instrument in the characterization of aerosols, along with guidance on sample preparation, specific characterization specific to the particular information sought in the analysis. Examples and guidance are given for each type of SIMS analysis.

  15. Synthesis and Mass Spectrometric Characterization of Organic Nitrates

    NASA Astrophysics Data System (ADS)

    Grünert, A.; Woidich, S.; Ballschmiter, K.

    2003-04-01

    Organic nitrates, as trace constituents in urban air, can be analyzed by adsorptive low volume sampling (LVS) as well as by adsorptive high volume sampling (HVS). Air samples ranging from 25 L to 100 L for the LVS and 100 m3 to 500 m3 for the (HVS) were collected, respectively. Analysis is performed by thermodesorption (LVS) or solvent elution combined with group separation (HVS) using normal-phase HPLC and high resolution capillary gas chromatography with electron capture detection (HRGC-ECD) and mass selective detection (HRGC-MSD). For identification and quantification available reference compounds are required for both methods (1;2). Following numbers of congeners of organic nitrate have been synthesized: 77 monoalkyl nitrates (C1-C16), 43 dialkyl nitrates (C2-C10), 37 hydroxy alkyl nitrates (C2-C8) and 41 carbonyl alkyl nitrates (C3-C12). Alkanes, alkenes, alcohols, ketones and halocarbons have been used as precursors. Characterisation of the reference compounds by retention-data and mass-spectra was performed by high resolution capillary gas chromatography with mass selective detection in the EI- and the NCI (CH4) mode (1-3). EI-ionization leads to the dominating indicator ion NO2+ for organic nitrates with m/z = 46 u. The characteristic fragments with NCI (CH4) show ions at m/z = 46 u and m/z = 62 u, corresponding to NO2- and NO3-. The use of flame ionisation detection (HRGC-FID) and the principle of the molar response for carbon allows the quantitation of reference solutions as the final tool for the determination of the levels and patterns of organic nitrates in urban air samples. (1) J. Kastler: "Analytik, Massenspektrometrie und Vorkommen multifunktioneller Alkylnitrate in belasteter und unbelasteter Atmosphäre" Dr.rer.nat.-Thesis, University of Ulm (1999) (2) G. Werner, J. Kastler, R. Looser, K. Ballschmiter: "Organic Nitrates of Isoprenes as Atmospheric Trace Compounds" Angew. Chem. Int. Ed. (1999) 38(11): 1634-1637 (3) S.Woidich, O. Froscheis, O

  16. Aerosol Chemistry Resolved by Mass Spectrometry: Linking Field Measurements of Cloud Condensation Nuclei Activity to Organic Aerosol Composition.

    PubMed

    Vogel, Alexander L; Schneider, Johannes; Müller-Tautges, Christina; Phillips, Gavin J; Pöhlker, Mira L; Rose, Diana; Zuth, Christoph; Makkonen, Ulla; Hakola, Hannele; Crowley, John N; Andreae, Meinrat O; Pöschl, Ulrich; Hoffmann, Thorsten

    2016-10-06

    Aerosol hygroscopic properties were linked to its chemical composition by using complementary online mass spectrometric techniques in a comprehensive chemical characterization study at a rural mountaintop station in central Germany in August 2012. In particular, atmospheric pressure chemical ionization mass spectrometry ((-)APCI-MS) provided measurements of organic acids, organosulfates, and nitrooxy-organosulfates in the particle phase at 1 min time resolution. Offline analysis of filter samples enabled us to determine the molecular composition of signals appearing in the online (-)APCI-MS spectra. Aerosol mass spectrometry (AMS) provided quantitative measurements of total submicrometer organics, nitrate, sulfate, and ammonium. Inorganic sulfate measurements were achieved by semionline ion chromatography and were compared to the AMS total sulfate mass. We found that up to 40% of the total sulfate mass fraction can be covalently bonded to organic molecules. This finding is supported by both on- and offline soft ionization techniques, which confirmed the presence of several organosulfates and nitrooxy-organosulfates in the particle phase. The chemical composition analysis was compared to hygroscopicity measurements derived from a cloud condensation nuclei counter. We observed that the hygroscopicity parameter (κ) that is derived from organic mass fractions determined by AMS measurements may overestimate the observed κ up to 0.2 if a high fraction of sulfate is bonded to organic molecules and little photochemical aging is exhibited.

  17. Development and application of a mass spectrometric system to study volatile components of fluid inclusions

    SciTech Connect

    Sloan, R.C. Jr.

    1992-06-01

    A quadrupole mass spectrometric system coupled with mechanical decrepitation was constructed and calibrated to study fluid inclusions from an active geothermal system. Fluid inclusions in Salton Sea Scientific Drilling Project well cores and ejects from flow tests were analyzed. Ion currents from selected mass/charge ratio numbers were measured for gases from ruptured inclusions in epidote, calcite, and hematite vein minerals from different depths. Water, carbon dioxide, hydrogen sulfide, sulfur dioxide, and C1{minus}C4+ hydrocarbons and free nitrogen were analyzed.

  18. A membrane-separator interface for mass-spectrometric analysis of blood plasma

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Gerasimov, D. G.

    2014-09-01

    We demonstrate the possibility of rapid mass-spectrometric determination of the content of anesthetic agents in blood plasma with the aid of a membrane-separator interface. The interface employs a hydrophobic selective membrane that is capable of separating various anesthetic drugs (including inhalation anesthetic sevofluran, noninhalation anesthetic thiopental, hypnotic propofol, and opioid analgesic fentanyl) from the blood plasma and introducing samples into a mass spectrometer. Analysis of the blood plasma was not accompanied by the memory effect and did not lead to membrane degradation. Results of clinical investigation of the concentration of anesthetics in the blood plasma of patients are presented.

  19. Mass spectrometric measurements of the isotopic anatomies of molecules (Invited)

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.; Krumwiede, D.; Schlueter, H.

    2013-12-01

    Site-specific and multiple isotopic substitutions in molecular structures potentially provide an extraordinarily rich set of constraints on their sources, conditions of formation, reaction and transport histories, and perhaps other issues. Examples include carbonate ';clumped isotope' thermometry, clumped isotope measurements of CO2, O2, and, recently, methane, ethane and N2O; site-specific 15N measurements in N2O and 13C and D analyses of fatty acids, sugars, cellulose, food products, and, recently, n-alkanes. Extension of the principles behind these tools to the very large number of isotopologues of complex molecules could potentially lead to new uses of isotope chemistry, similar to proteomics, metabolomics and genomics in their complexity and depth of detail (';isotomics'?). Several technologies are potentially useful for this field, including ';SNIF-NMR', gas source mass spectrometry and IR absorption spectroscopy. However, all well established methods have restrictive limits in the sizes of samples, types of analyzes, and the sorts of isotopologues that can be measured with useful precision. We will present an overview of several emerging instruments and techniques of high-resolution gas source mass spectrometry that may enable study of a large proportion of the isotopologues of a wide range of volatile and semi-volatile compounds, including many organics, with precisions and sample sizes suitable for a range of applications. A variety of isotopologues can be measured by combining information from the Thermo 253 Ultra (a new high resolution, multi-collector gas source mass spectrometer) and the Thermo DFS (a very high resolution single collector, but used here on a novel mode to achieve ~per mil precision ratio measurements), sometimes supplemented by conventional bulk isotopic measurements. It is possible to design methods in which no one of these sources of data meaningfully constrain abundances of specific isotopologues, but their combination fully and

  20. Ambient aerodynamic ionization source for remote analyte sampling and mass spectrometric analysis.

    PubMed

    Dixon, R Brent; Sampson, Jason S; Hawkridge, Adam M; Muddiman, David C

    2008-07-01

    The use of aerodynamic devices in ambient ionization source development has become increasingly prevalent in the field of mass spectrometry. In this study, an air ejector has been constructed from inexpensive, commercially available components to incorporate an electrospray ionization emitter within the exhaust jet of the device. This novel aerodynamic device, herein termed remote analyte sampling, transport, and ionization relay (RASTIR) was used to remotely sample neutral species in the ambient and entrain them into an electrospray plume where they were subsequently ionized and detected using a linear ion trap Fourier transform mass spectrometer. Two sets of experiments were performed in the ambient environment to demonstrate the device's utility. The first involved the remote (approximately 1 ft) vacuum collection of pure sample particulates (i.e., dry powder) from a glass slide, entrainment and ionization at the ESI emitter, and mass spectrometric detection. The second experiment involved the capture (vacuum collection) of matrix-assisted laser desorbed proteins followed by entrainment in the ESI emitter plume, multiple charging, and mass spectrometric detection. This approach is in principle a RASTIR-assisted matrix-assisted laser desorption electrospray ionization source (Sampson, J. S.; Hawkridge, A. M.; Muddiman, D. C. J. Am. Soc. Mass Spectrom. 2006, 17, 1712-1716; Rapid Commun. Mass Spectrom. 2007, 21, 1150-1154.). A detailed description of the device construction, operational parameters, and preliminary small molecule and protein data are presented.

  1. Next generation of food allergen quantification using mass spectrometric systems.

    PubMed

    Koeberl, Martina; Clarke, Dean; Lopata, Andreas L

    2014-08-01

    Food allergies are increasing worldwide and becoming a public health concern. Food legislation requires detailed declarations of potential allergens in food products and therefore an increased capability to analyze for the presence of food allergens. Currently, antibody-based methods are mainly utilized to quantify allergens; however, these methods have several disadvantages. Recently, mass spectrometry (MS) techniques have been developed and applied to food allergen analysis. At present, 46 allergens from 11 different food sources have been characterized using different MS approaches and some specific signature peptides have been published. However, quantification of allergens using MS is not routinely employed. This review compares the different aspects of food allergen quantification using advanced MS techniques including multiple reaction monitoring. The latter provides low limits of quantification for multiple allergens in simple or complex food matrices, while being robust and reproducible. This review provides an overview of current approaches to analyze food allergens, with specific focus on MS systems and applications.

  2. Thermogravimetric-mass spectrometric analysis on combustion of lignocellulosic biomass.

    PubMed

    López-González, D; Fernandez-Lopez, M; Valverde, J L; Sanchez-Silva, L

    2013-09-01

    Combustion characteristics of biomass main components and three lignocellulosic biomass (fir wood, eucalyptus wood and pine bark) were investigated by thermogravimetric analysis coupled with mass spectrometry. The combustion of biomass was divided into two main steps, devolatilization and char oxidation stage. Heating rate effect was also studied. Generally, the higher the heating rate, the higher the decomposition temperature. Furthermore, the weight loss rate decreased due to particle temperature gradients. Combustion kinetics were studied. Models based on reaction order (Oi), nucleation (Ni) and diffusion (Di) achieved the best fitting to the experimental data. Cellulose oxidation presented the highest activation energies. CO, CO2 and H2O were the main components evolved from combustion. Additionally, light hydrocarbons (CH4 and C2H5) were also present. Finally, nitrogen compounds were in a higher proportion than sulfur compounds being released as primary amines and NOx.

  3. Comprehensive mass spectrometric analysis of novel organic semiconductor molecules

    NASA Astrophysics Data System (ADS)

    Prada, Svitlana

    This work presents a comprehensive mass spectrometry (MS) study of novel organic semiconductor molecules including ion mobility/reactivity measurements and trace elemental analysis. The organic molecules investigated here are important semiconductor materials for molecular electronic devices such as Organic Field-Effect Transistors (OFETs) and Light Emitted Diodes (LED). A high-performance orthogonal time-of flight mass spectrometer (TOF-MS) in combination with a matrix assisted laser desorption/ionization (MALDI) source operating at elevated pressure was used to perform MALDI/TOF analyses of pentacene and some of its derivatives with and without an added matrix. The observation of ion-molecule reactions between "cold" analyte ions and neutral analyte molecules in the gas phase has provided some insight into the mechanism of pentacene cluster formation and its functionalized derivatives. Furthermore, some of the matrices employed to assist the desorption/ionization process of these compounds were observed to influence the outcome via ion-molecule reactions of analyte ions and matrix molecules in the gas phase. The stability and reactivity of the compounds and their clusters in the MALDI plume during gas-phase expansion were evaluated; possible structures of the resulting clusters are discussed. The MALDI/TOF technique was also helpful in distinguishing between two isomeric forms of bis-[(triisopropylsilyl)-ethynyl]-pentacene. Furthermore, we reported ion mobility measurements of functionalized pentacene ions with a modified triple quadrupole mass spectrometer fitted with an ion molecule reactor (IMR). The IMR is equipped with a variable axial electrostatic drift field (ADF) and is able to trap ions for a prolong period of time. These capabilities were successfully employed in the measurement of ion mobilities in different modes of the IMR operation. Theoretical modeling of the drift dynamics and the special localization of the large ion packet was successfully

  4. Quantitative mass spectrometric analysis of glycoproteins combined with enrichment methods.

    PubMed

    Ahn, Yeong Hee; Kim, Jin Young; Yoo, Jong Shin

    2015-01-01

    Mass spectrometry (MS) has been a core technology for high sensitive and high-throughput analysis of the enriched glycoproteome in aspects of quantitative assays as well as qualitative profiling of glycoproteins. Because it has been widely recognized that aberrant glycosylation in a glycoprotein may involve in progression of a certain disease, the development of efficient analysis tool for the aberrant glycoproteins is very important for deep understanding about pathological function of the glycoprotein and new biomarker development. This review first describes the protein glycosylation-targeting enrichment technologies mainly employing solid-phase extraction methods such as hydrizide-capturing, lectin-specific capturing, and affinity separation techniques based on porous graphitized carbon, hydrophilic interaction chromatography, or immobilized boronic acid. Second, MS-based quantitative analysis strategies coupled with the protein glycosylation-targeting enrichment technologies, by using a label-free MS, stable isotope-labeling, or targeted multiple reaction monitoring (MRM) MS, are summarized with recent published studies.

  5. Imaging Mass Spectrometric Analysis of Neurotransmitters: A Review

    PubMed Central

    Romero-Perez, Gustavo A.; Takei, Shiro; Yao, Ikuko

    2014-01-01

    Imaging mass spectrometry (IMS) is a toolbox of versatile techniques that enable us to investigate analytes in samples at molecular level. In recent years, IMS, and especially matrix-assisted laser desorption/ionisation (MALDI), has been used to visualise a wide range of metabolites in biological samples. Simultaneous visualisation of the spatial distribution of metabolites in a single sample with little tissue disruption can be considered as one important advantage of MALDI over other techniques. However, several technical hurdles including low concentrations and rapid degradation rates of small molecule metabolites, matrix interference of signals and poor ionisation, need to be addressed before MALDI can be considered as a reliable tool for the analysis of metabolites such as neurotransmitters in brain tissues from different sources including humans. In the present review we will briefly describe current MALDI IMS techniques used to study neurotransmitters and discuss their current status, challenges, as well as future prospects. PMID:26819893

  6. Capillary electrophoretic and mass spectrometric analysis of a polydisperse fluorosurfactant.

    PubMed

    Al-Jarah, Suhair Yousif; Sjödahl, Johan; Woldegiorgis, Andreas; Emmer, Asa

    2005-02-01

    A fluorosurfactant has been studied using capillary electrophoresis and mass spectrometry. The fluorosurfactant, FC134, can be used as a buffer additive in capillary electrophoresis in order to decrease wall adsorption of proteins and in micellar electrokinetic chromatography. However, it has been discovered that this fluorosurfactant is polydisperse, thus containing substances with different lengths and structures. In this work, the fluorosurfactant sample components were separated by capillary electrophoresis. An uncoated as well as a poly(vinyl alcohol)-coated capillary were used with running electrolytes containing methanol and acetic acid. Following the capillary electrophoretic separation, fractions were collected for further analysis by MALDI-MS. Non-fractionated samples were also analyzed both by MALDI-MS and by ESI-MS.

  7. Mass spectrometric methods for monitoring redox processes in electrochemical cells.

    PubMed

    Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

    2015-01-01

    Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation-reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common.

  8. Mass spectrometric characterization of the Rosetta Spacecraft contamination

    NASA Astrophysics Data System (ADS)

    Bieler, A.; Altwegg, K.; Balsiger, H.; Berthelier, J.-J.; Calmonte, U.; Combi, M.; De Keyser, J.; Fiethe, B.; Fuselier, S. A.; Gasc, S.; Gombosi, T.; Hansen, K. C.; Hässig, M.; Korth, A.; Le Roy, L.; Mall, U.; Rème, H.; Rubin, M.; Sémon, T.; Tenishev, V.; Tzou, C.-Y.; Waite, J. H.; Wurz, P.

    2016-09-01

    Mass spectrometers are valuable tools for the in situ characterization of gaseous exo- and atmospheres and have been operated at various bodies in space. Typical measurements derive the elemental composition, relative abundances, and isotopic ratios of the examined environment. To sample tenuous gas environments around comets, icy moons, and the exosphere of Mercury, efficient instrument designs with high sensitivity are mandatory while the contamination by the spacecraft and the sensor itself should be kept as low as possible. With the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), designed to characterize the coma of comet 67P/Churyumov-Gerasimenko, we were able to quantify the effects of spacecraft contamination on such measurements. By means of 3D computational modeling of a helium leak in the thruster pressurization tubing that was detected during the cruise phase we examine the physics involved leading to the measurements of contamination. 3 types of contamination can be distinguished: i) Compounds from the decomposition of the spacecraft material. ii) Contamination from thruster firing during maneuvers. iii) Adsorption and desorption of the sampled environment on and from the spacecraft. We show that even after more than ten years in space the effects of i) are still detectable by ROSINA and impose an important constraint on the lower limit of gas number densities one can examine by means of mass spectrometry. Effects from ii) act on much shorter time scales and can be avoided or minimized by proper mission planning and data analysis afterwards. iii) is the most difficult effect to quantify as it changes over time and finally carries the fingerprint of the sampled environment which makes prior calibration not possible.

  9. Mass spectrometric methods for monitoring redox processes in electrochemical cells

    PubMed Central

    Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

    2015-01-01

    Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation–reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common. PMID:24338642

  10. A review on the mass spectrometric studies of americium: Present status and future perspective.

    PubMed

    Aggarwal, Suresh Kumar

    2016-05-06

    The manuscript reviews the various mass spectrometric techniques for analysis and chemical studies of Americium. These methods include thermal ionization mass spectrometry (TIMS), and inductively coupled plasma source mass spectrometry (ICPMS) for the determination of Am isotope ratios and concentration in nuclear fuel samples of interest in nuclear technology, and in complex biological and environmental samples. Ultra-sensitive mass spectrometric techniques of resonance-ionization mass spectrometry (RIMS), and accelerator-based mass spectrometry (AMS) are also discussed. The novel applications of electrospray ionization mass spectrometry (ESIMS) to understand the solution chemistry of Am and other actinides are presented. These studies are important in view of the world-wide efforts to develop novel complexing agents to separate lanthanides and minor actinides (Am, Np, and Cm) for partitioning and transmutation of minor actinides from the point of view of nuclear waste management. These mass spectrometry experiments are also of great interest to examine the covalent character of actinides with increasing atomic number. Studies on gas-phase chemistry of Am and its oxides with Knudsen effusion mass spectrometry (KEMS), Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS), and laser-based experiments with reflectron time-of-flight mass spectrometer (R-ToF) are highlighted. These studies are important to understand the fundamental chemistry of 5f electrons in actinides. Requirement of certified isotopic reference materials of Am to improve the accuracy of experimental nuclear data (e.g., the half-life of (243) Am) is emphasized. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

  11. A Mass Spectrometric-Derived Cell Surface Protein Atlas

    PubMed Central

    Bausch-Fluck, Damaris; Hofmann, Andreas; Bock, Thomas; Frei, Andreas P.; Cerciello, Ferdinando; Jacobs, Andrea; Moest, Hansjoerg; Omasits, Ulrich; Gundry, Rebekah L.; Yoon, Charles; Schiess, Ralph; Schmidt, Alexander; Mirkowska, Paulina; Härtlová, Anetta; Van Eyk, Jennifer E.; Bourquin, Jean-Pierre; Aebersold, Ruedi; Boheler, Kenneth R.; Zandstra, Peter; Wollscheid, Bernd

    2015-01-01

    Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome) of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC) technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA) providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa). The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments. PMID:25894527

  12. High-throughput mass spectrometric cytochrome P450 inhibition screening.

    PubMed

    Lim, Kheng B; Ozbal, Can C; Kassel, Daniel B

    2013-01-01

    We describe here a high-throughput assay to support rapid evaluation of drug discovery compounds for possible drug-drug interaction (DDI). Each compound is evaluated for its DDI potential by incubating over a range of eight concentrations and against a panel of six cytochrome P450 (CYP) enzymes: 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. The method utilizes automated liquid handling for sample preparation, and online solid-phase extraction/tandem mass spectrometry (SPE/MS/MS) for sample analyses. The system is capable of generating two 96-well assay plates in 30 min, and completes the data acquisition and analysis of both plates in about 30 min. Many laboratories that perform the CYP inhibition screening automate only part of the processes leaving a throughput bottleneck within the workflow. The protocols described in this chapter are aimed to streamline the entire process from assay to data acquisition and processing by incorporating automation and utilizing high-precision instrument to maximize throughput and minimize bottleneck.

  13. Mass spectrometric studies of fast pyrolysis of cellulose.

    PubMed

    Degenstein, John C; Hurt, Matt; Murria, Priya; Easton, McKay; Choudhari, Harshavardhan; Yang, Linan; Riedeman, James; Carlsen, Mark S; Nash, John J; Agrawal, Rakesh; Delgass, W Nicholas; Ribeiro, Fabio H; Kenttämaa, Hilkka I

    2015-01-01

    A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: the formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.

  14. Desorption chemical ionization and fast atom bombardment mass spectrometric studies of the glucuronide metabolites of doxylamine.

    PubMed

    Lay, J O; Korfmacher, W A; Miller, D W; Siitonen, P; Holder, C L; Gosnell, A B

    1986-11-01

    Three glucuronide metabolites of doxylamine succinate were collected in a single fraction using high-performance liquid chromatography (HPLC) from the urine of dosed male Fischer 344 rats. The metabolites were then separated using an additional HPLC step into fractions containing predominantly a single glucuronide metabolite. Analysis of the metabolites by methane and ammonia desorption chemical ionization, with and without derivatization, revealed fragment ions suggestive of a hydroxylated doxylamine moiety. Identification of the metabolites as glucuronides of doxylamine, desmethyldoxylamine and didesmethyldoxylamine was accomplished, based on determination of the molecular weight and exact mass of each metabolite using fast atom bombardment (FAB) ionization. This assignment was confirmed by the fragmentation observed in FAB mass spectrometric and tandem mass spectrometric experiments. Para-substitution of the glucuronide on the phenyl moiety was observed by 500-MHz nuclear magnetic resonance (NMR) spectrometry. A fraction containing all three glucuronide metabolites, after a single stage of HPLC separation, was also analysed by FAB mass spectrometry, and the proton- and potassium-containing quasimolecular ions for all three metabolites were observed.

  15. Application of mass spectrometric techniques for the trace analysis of short-lived iodine-containing volatiles emitted by seaweed.

    PubMed

    Kundel, Michael; Thorenz, Ute R; Petersen, Jan H; Huang, Ru-Jin; Bings, Nicolas H; Hoffmann, Thorsten

    2012-04-01

    Knowledge of the composition and emission rates of iodine-containing volatiles from major widespread seaweed species is important for modeling the impact of halogens on gas-phase atmospheric chemistry, new particle formation, and climate. In this work, we present the application of mass spectrometric techniques for the quantification of short-lived iodine-containing volatiles emitted by eight different seaweeds from the intertidal zone of Helgoland, Germany. A previously developed online time-of-flight aerosol mass spectrometric method was used to determine I(2) emission rates and investigate temporally resolved emission profiles. Simultaneously, iodocarbons were preconcentrated on solid adsorbent tubes and quantified offline using thermodesorption-gas chromatography-mass spectrometry. The total iodine content of the seaweeds was determined using microwave-assisted tetramethylammonium hydroxide extraction followed by inductively coupled-plasma mass spectrometry analysis. The highest total iodine content was found in the Laminariales, followed by the brown algae Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, and both red algae Chondrus crispus and Delesseria sanguinea. Laminariales were found to be the strongest I(2) emitters. Time series of the iodine release of Laminaria digitata and Laminaria hyperborea showed a strong initial I(2) emission when first exposed to air followed by an exponential decline of the release rate. For both species, I(2) emission bursts were observed. For Laminaria saccharina und F. serratus, a more continuous I(2) release profile was detected, however, F. serratus released much less I(2). A. nodosum and F. vesiculosus showed a completely different emission behavior. The I(2) emission rates of these species were slowly increasing with time during the first 1 to 2 h until a more or less stable I(2) emission rate was reached. The lowest I(2) emission rates were detected for the red algae C. crispus and D. sanguinea. Total iodocarbon

  16. Tandem mass spectrometric fragmentation patterns of known and new steviol glycosides with structure proposals.

    PubMed

    Zimmermann, Benno F

    2011-06-15

    Stevia rebaudiana contains several steviol glycosides that have a sweet flavor. They are up to 450 times sweeter than sucrose, but some have an undesirable aftertaste. Up to 2010, ten different steviol glycosides have been described from the leaves or purified extracts of S. rebaudiana. In this paper, the tandem mass spectrometric fragmentation patterns of these ten compounds are compiled, along with a scheme for structural elucidation. This scheme is then applied to 12 steviol glycosides that have not yet been described. The proposed structures of five steviol glycosides have been confirmed by other authors.

  17. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity

    PubMed Central

    Kalb, Suzanne R.; Boyer, Anne E.; Barr, John R.

    2015-01-01

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A–G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin. PMID:26404376

  18. Mass Spectrometric Detection of Bacterial Protein Toxins and Their Enzymatic Activity.

    PubMed

    Kalb, Suzanne R; Boyer, Anne E; Barr, John R

    2015-08-31

    Mass spectrometry has recently become a powerful technique for bacterial identification. Mass spectrometry approaches generally rely upon introduction of the bacteria into a matrix-assisted laser-desorption time-of-flight (MALDI-TOF) mass spectrometer with mass spectrometric recognition of proteins specific to that organism that form a reliable fingerprint. With some bacteria, such as Bacillus anthracis and Clostridium botulinum, the health threat posed by these organisms is not the organism itself, but rather the protein toxins produced by the organisms. One such example is botulinum neurotoxin (BoNT), a potent neurotoxin produced by C. botulinum. There are seven known serotypes of BoNT, A-G, and many of the serotypes can be further differentiated into toxin variants, which are up to 99.9% identical in some cases. Mass spectrometric proteomic techniques have been established to differentiate the serotype or toxin variant of BoNT produced by varied strains of C. botulinum. Detection of potent biological toxins requires high analytical sensitivity and mass spectrometry based methods have been developed to determine the enzymatic activity of BoNT and the anthrax lethal toxins produced by B. anthracis. This enzymatic activity, unique for each toxin, is assessed with detection of the toxin-induced cleavage of strategically designed peptide substrates by MALDI-TOF mass spectrometry offering unparalleled specificity. Furthermore, activity assays allow for the assessment of the biological activity of a toxin and its potential health risk. Such methods have become important diagnostics for botulism and anthrax. Here, we review mass spectrometry based methods for the enzymatic activity of BoNT and the anthrax lethal factor toxin.

  19. Assessment of current mass spectrometric workflows for the quantification of low abundant proteins and phosphorylation sites

    PubMed Central

    Bauer, Manuel; Ahrné, Erik; Baron, Anna P.; Glatter, Timo; Fava, Luca L.; Santamaria, Anna; Nigg, Erich A.; Schmidt, Alexander

    2015-01-01

    The data described here provide a systematic performance evaluation of popular data-dependent (DDA) and independent (DIA) mass spectrometric (MS) workflows currently used in quantitative proteomics. We assessed the limits of identification, quantification and detection for each method by analyzing a dilution series of 20 unmodified and 10 phosphorylated synthetic heavy labeled reference peptides, respectively, covering six orders of magnitude in peptide concentration with and without a complex human cell digest background. We found that all methods performed very similarly in the absence of background proteins, however, when analyzing whole cell lysates, targeted methods were at least 5–10 times more sensitive than directed or DDA methods. In particular, higher stage fragmentation (MS3) of the neutral loss peak using a linear ion trap increased dynamic quantification range of some phosphopeptides up to 100-fold. We illustrate the power of this targeted MS3 approach for phosphopeptide monitoring by successfully quantifying 9 phosphorylation sites of the kinetochore and spindle assembly checkpoint component Mad1 over different cell cycle states from non-enriched pull-down samples. The data are associated to the research article ‘Evaluation of data-dependent and data-independent mass spectrometric workflows for sensitive quantification of proteins and phosphorylation sites׳ (Bauer et al., 2014) [1]. The mass spectrometry and the analysis dataset have been deposited to the ProteomeXchange Consortium (http://proteomecentral.proteomexchange.org) via the PRIDE partner repository with the dataset identifier PXD000964. PMID:26550600

  20. Parallel Detection of Intrinsic Fluorescence from Peptides and Proteins for Quantification During Mass Spectrometric Analysis

    PubMed Central

    Russell, Jason D.; Hilger, Ryan T.; Ladror, Daniel T.; Tervo, Mark A.; Scalf, Mark; Shortreed, Michael R.; Coon, Joshua J.

    2011-01-01

    Direct mass spectrometric quantification of peptides and proteins is compromised by the wide variabilities in ionization efficiency which are hallmarks of both the MALDI and ESI ionization techniques. We describe here the implementation of a fluorescence detection system for measurement of the UV-excited intrinsic fluorescence (UV-IF) from peptides and proteins just prior to their exit and electrospray ionization from an ESI capillary. The fluorescence signal provides a quantifiable measure of the amount of the protein or peptide present, while direct or tandem mass spectrometric analysis (MS/MS) on the ESI-generated ions provides information on identity. We fabricated an inexpensive, modular, fluorescence excitation and detection device utilizing an ultraviolet light-emitting diode for excitation in a ~300 nL fluorescence detection cell integrated into the fused-silica separation column. The fluorescence signal was linear over 3 orders of magnitude with on-column limits of detection in the low femtomole range. Chromatographically separated intact proteins analyzed using UV-IF prior to top-down mass spectrometry demonstrated sensitive detection of proteins as large as 77 kDa. PMID:21314137

  1. Mass spectrometric peptide mapping analysis and structural characterization of dihydrodiol dehydrogenase isoenzymes.

    PubMed Central

    Gauss, C; Klein, J; Post, K; Suckau, D; Schneider, K; Thomas, H; Oesch, F; Przybylski, M

    1990-01-01

    The direct molecular weight determination and structural analysis of polypeptides and peptide mixtures have become amenable by the recent development of fast atom bombardment (FABMS) and 252Cf-plasma desorption (PDMS) mass spectrometry. FABMS and PDMS peptide mapping, i.e., the direct analysis of peptide mixtures resulting from proteolytic digestion, have been developed as powerful methods for the structural characterization of epoxide-metabolizing isoenzymes. The major advantage of this approach is provided by the selectivity of the endoproteolytic cleavage, combined with the specific and accurate molecular weight determination of complex digest mixtures containing peptides up to several thousands daltons in size. Furthermore, the mass spectrometric peptide mapping analysis can be combined with a range of protein-chemical modification reactions and with sequential degradation such as by carboxypeptidases. Both FABMS and PDMS peptide mapping have already been successfully applied to the structural differentiation of glutathione transferase and epoxide hydrolase isoenzymes in cases where references sequence data for at least one isoenzyme form was available. In the application described here, for a series of dihydrodiol dehydrogenase (DDH) isoenzymes with hitherto undetermined primary structures, a direct correlation between the structural differentiation from peptide mapping data and differences in their substrate specificities could be demonstrated. The mass spectrometric peptide mapping analysis of isoenzymes proved to be an efficient basis for the elucidation of the structure of one major DDH isoenzyme form; partial sequence data for this protein are reported. PMID:2272334

  2. Proteogenomics meets cancer immunology: mass spectrometric discovery and analysis of neoantigens.

    PubMed

    Polyakova, Anna; Kuznetsova, Ksenia; Moshkovskii, Sergei

    2015-01-01

    Cancer proteogenomics is an emerging field that aims to identify and quantify protein sequence changes associated with the cancer genome. Besides being involved in cancer development and progression, such protein variants may serve as neoantigens, which provide the T-cell response against tumors. Mass spectrometry-based proteogenomics may be a promising tool for finding neoantigens in individual specimens. It is partly based on a technical background accumulated from mass spectrometric studies of peptide ligands of major histocompatibility complex proteins. Examples of the use of mass spectrometry in neoantigen identification are reviewed in this article. Some experimental workflows are discussed, which may use shotgun and targeted proteomics for translational human studies of neoepitopes, such as cancer vaccine development and checkpoint therapy response prediction.

  3. Chromatographic and mass spectrometric fingerprinting analyses of Angelica sinensis (Oliv.) Diels-derived dietary supplements.

    PubMed

    Zhao, Yang; Sun, Jianghao; Yu, Liangli Lucy; Chen, Pei

    2013-05-01

    Angelica sinensis (Oliv.) Diels ("Danggui" in Chinese) is one of the most commonly used traditional Chinese medicines. It has been used to invigorate blood circulation for the treatment of anemia, hypertension, chronic bronchitis, asthma, rheumatism, and cardiovascular diseases. There are a number of A. sinensis-derived dietary supplements in the US markets. However, no study have been conducted to investigate the quality of these dietary supplements. In this paper, high-performance liquid chromatographic and flow-injection mass spectrometric fingerprints were both evaluated to assess the consistency of A. sinensis-derived dietary supplements. Similarity analysis was carried out on the high-performance liquid chromatographic (HPLC) fingerprints. Meanwhile, principal component analysis (PCA) was performed on the data obtained from flow-injection mass spectrometric (FIMS) fingerprints, which can analyze each sample in 2 min, compared with 30 min required for the chromatographic fingerprint. Both methods show significant chemical differences between samples that may be due to differences in growing locations, growing conditions, harvesting times, and/or botanical processing. The loading plots obtained from PCA singled out the discriminatory ions that were responsible for chemical differences of A. sinensis-derived dietary supplements.

  4. The Bremen mass spectrometric facility for the measurement of helium isotopes, neon, and tritium in water.

    PubMed

    Sültenfuss, Jürgen; Roether, Wolfgang; Rhein, Monika

    2009-06-01

    We describe the mass spectrometric facility for measuring helium isotopes, neon, and tritium that has been operative at this institute since 1989, and also the sampling and sample preparation steps that precede the mass spectrometric analysis. For water samples in a near-equilibrium with atmospheric air, the facility achieves precision for (3)He/(4)He ratios of+/-0.4% or better, and+/-0.8 % or better for helium and neon concentrations. Tritium precision is typically+/-3 % and the detection limit 10 mTU ( approximately 1.2.10(-3) Bq/kg of pure water). Sample throughputs can reach some thousands per year. These achievements are enabled, among other features, by automation of the measurement procedure and by elaborate calibration, assisted by continual development in detail. To date, we have measured more than 15,000 samples for tritium and 23,000 for helium isotopes and neon, mostly in the context of oceanographic and hydrologic work. Some results of such work are outlined. Even when atmospheric tritium concentrations have become rather uniform, tritium provides water ages if (3)He data are taken concurrently. The technique can resolve tritium concentrations in waters of the pre-nuclear era.

  5. MALDI mass spectrometric imaging meets "omics": recent advances in the fruitful marriage.

    PubMed

    Crecelius, A C; Schubert, U S; von Eggeling, F

    2015-09-07

    Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI MSI) is a method that allows the investigation of the molecular content of surfaces, in particular, tissues, within its morphological context. The applications of MALDI MSI in the field of large-scale mass spectrometric studies, which are typically denoted by the suffix "omics", are steadily increasing. This is because, on the one hand, technical advances regarding sample collection and preparation, matrix application, instrumentation, and data processing have enhanced the molecular specificity and sensitivity of MALDI MSI; on the other hand, the focus of the "omics" community has moved from establishing an inventory of certain compound classes to exploring their spatial distribution to gain novel insights. Thus, the aim of this mini-review is twofold, to display the state-of-the-art in terms of technical aspects in MALDI MSI and to highlight selected applications in the last two years, which either have significantly advanced a certain "omics" field or have introduced a new one through pioneering efforts.

  6. Gas chromatographic-mass spectrometric analysis of volatile amines produced by several strains of Clostridium.

    PubMed

    Pons, J L; Rimbault, A; Darbord, J C; Leluan, G

    1985-02-08

    A gas chromatographic--mass spectrometric technique is proposed for the analysis of volatile amines which were isolated from Clostridium cultures by vacuum distillation and concentrated as hydrochloride salts. Headspace sampling after alkalinization of the salts under vacuum was the most suitable for subsequent gas chromatographic analysis. With ammonia-loaded helium as carrier gas, methylamines were separated on 4.8% PEG 2OM + 0.3% potassium hydroxide on Carbopack B, and other volatile amines on 28% Pennwalt 223 + 4% potassium hydroxide on Gas-Chrom R. Bacterial volatile amines (dimethylamine, trimethylamine, isobutylamine, 3-methylbutylamine, etc.) were detected with a flame-ionization detector and identified by gas chromatography--mass spectrometry in electron-impact and chemical ionization modes.

  7. Mass spectrometric determination of acromelic acid A from a new poisonous mushroom: Clitocybe amoenolens.

    PubMed

    Bessard, J; Saviuc, P; Chane-Yene, Y; Monnet, S; Bessard, G

    2004-11-05

    As Clitocybe acromelalga, the mushroom Clitocybe amoenolens is responsible for erythermalgia. Acromelic acids isolated from C. acromelalga have been suspected to be to some extend the active principles. The objective was to develop a specific and sensitive liquid chromatographic-mass spectrometric method that would allow acromelic acid A identification and quantification in mushrooms. The method involved a single-step methanol-water extraction followed by a selective cleanup of the extract with solid-phase extraction cartridges (strong-anion exchange). The chromatographic separation was achieved on a porous graphitic carbon column with acetonitrile-water-formic acid as mobile phase. Detection was done with a mass analyzer equipped with a TurboIonSpray source, operated in the negative ionization mode. Acromelic acid A concentration was determined in dried mushroom at around 325 ng/mg in C. amoenolens and 283 ng/mg in C. acromelalga.

  8. Identification of volatiles by headspace gas chromatography with simultaneous flame ionization and mass spectrometric detection.

    PubMed

    Tiscione, Nicholas B; Yeatman, Dustin Tate; Shan, Xiaoqin; Kahl, Joseph H

    2013-10-01

    Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon®-11), dichlorodifluoromethane (Freon®-12), dichlorofluoromethane (Freon®-21), chlorodifluoromethane (Freon®-22) and 1,2-dichlorotetrafluoroethane (Freon®-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness.

  9. Mass-spectrometric online monitoring of metabolism for estimation of adequacy of anesthesia

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.; Faizov, I. I.; Shchegolev, A. V.

    2012-08-01

    The possibility of using a mass-spectrometric method for estimation of the adequacy of anesthesia has been demonstrated. The method is based on online monitoring of metabolism by determining the CO2/O2 concentration ratio during expiration in each breathing cycle, which allows the patient's response to surgical injury in the course of total anesthesia to be evaluated. The proposed method has been clinically tested using an electron-impact ionization mass spectrometer connected to the breathing circuit of an inhalation anesthesia machine. It is shown that, using this technique, the time of the patient's organism response to drug correction of the adequacy of lung ventilation during anesthesia can be monitored online.

  10. On-line mass spectrometric monitoring of the polymerization of a phenolic-resin-based material

    NASA Technical Reports Server (NTRS)

    Aikens, D. A.; Wood, G. M.; Upchurch, B. T.

    1975-01-01

    Polymerization of phenolic-resin-based materials requires elevated temperatures. The low thermal conductivity of these materials has led to the use of dielectric heating techniques in lieu of standard convection oven heating to obtain a satisfactory cure. The curing rate and therefore the quality of the cured material depends on the heating rate and maximum temperature attained, parameters which are extremely difficult to measure in dielectric heating units. The dielectric curing of these materials was monitored by using a mass spectrometer to measure the partial pressure of phenol in the gas evolved during polymerization. The resulting plots of phenol partial pressure as a function of time have a characteristic shape, and these may be used to indicate the attainment of complete curing. The validity of the mass spectrometric technique was confirmed by chemical analysis of the polymerized samples.

  11. Absorption spectrum, mass spectrometric properties, and electronic structure of 1,2-benzoquinone.

    PubMed

    Albarran, Guadalupe; Boggess, William; Rassolov, Vitaly; Schuler, Robert H

    2010-07-22

    Absorption spectrophotometric and mass spectrometric properties of 1,2-benzoquinone, prepared in aqueous solution by the hexachloroiridate(IV) oxidation of catechol and isolated by HPLC, are reported. Its absorption spectrum has a broad moderately intense band in the near UV with an extinction coefficient of 1370 M(-1)cm(-1) at its 389 nm maximum. The oscillator strength of this band contrasts with those of the order-of-magnitude stronger approximately 250 nm bands of most 1,4-benzoquinones. Gaussian analysis of its absorption spectrum indicates that it also has modestly intense higher energy bands in the 250-320 nm region. In atmospheric pressure mass spectrometric studies 1,2-benzoquinone exhibits very strong positive and negative mass 109 signals that result from the addition of protons and hydride ions in APCI and ESI ion sources. It is suggested that the hydride adduct is formed as the result of the highly polar character of ortho-quinone. On energetic collision the hydride adduct loses an H atom to produce the 1,2-benzosemiquinone radical anion. The present studies also show that atmospheric pressure mass spectral patterns observed for catechol are dominated by signals of 1,2-benzoquinone resulting from oxidation of catechol in the ion sources. Computational studies of the electronic structures of 1,2-benzoquinone, its proton and hydride ion adducts, and 1,2-benzosemiquinone radical anion are reported. These computational studies show that the structures of the proton and hydride adducts are similar and indicate that the hydride adduct is the proton adduct of a doubly negatively charged 1,2-benzoquinone. The contrast between the properties of 1,2- and 1,4-benzoquinone provides the basis for considerations on the effects of conjugation in aromatic systems.

  12. Mass spectrometric behaviour of carboxylated polyethylene glycols and carboxylated octylphenol ethoxylates.

    PubMed

    Frańska, Magdalena; Zgoła, Agnieszka; Rychłowska, Joanna; Szymański, Andrzej; Łukaszewski, Zenon; Frański, Rafał

    2003-01-01

    Mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) are discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali metal cations) of carboxylated PEGs was compared with that of non-carboxylated correspondents by using both secondary ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral correspondents, PEGs. The B/E mass spectra were recorded, using secondary ion mass spectrometry as a method for generation, for deprotonated and protonated molecules and molecules cationised by alkali metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxylic groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H](-) ions proceed through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain leading to the octylphenoxy anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative ion mode were found to be more suitable for the determination of the average molecular weight of carboxylated ethoxylates than SI mass spectra.

  13. Cu2+-assisted two dimensional charge-mass double focusing gel electrophoresis and mass spectrometric analysis of histone variants.

    PubMed

    Zhang, Wenyang; Tang, Xuemei; Ding, Mengjie; Zhong, Hongying

    2014-12-10

    Abundant isoforms and dynamic posttranslational modifications cause the separation and identification of histone variants to be experimentally challenging. To meet this need, we employ two-dimensional electrophoretic gel separation followed by mass spectrometric detection which takes advantage of the chelation of Cu(2+) with amino acid residues exposed on the surfaces of the histone proteins. Acid-extracted rat liver histones were first mixed with CuSO4 solution and then separated in one dimension with triton-acid-urea (TAU) gel electrophoresis and in a second dimension using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The separations result from both the changes in charge and mass upon Cu(2+) chelation. Identities of each separated gel bands were obtained by using matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS). It was found that the migration of H3 histone isoforms of rat liver is markedly affected by the use of Cu(2+) ions.

  14. Allatotropin-related peptide in cockroaches: identification via mass spectrometric analysis of single identified neurons.

    PubMed

    Neupert, Susanne; Schattschneider, Sebastian; Predel, Reinhard

    2009-03-01

    The first insect allatotropin-related peptide (ATRP) was isolated from head extracts of the adult sphinx moth Manduca sexta [Kataoka H, Toschi A, Li JP, Carney RL, Schooley DA, Kramer SJ. Identification of an allatotropin from adult Manduca sexta. Science 1989;243:1481-3.]. Meanwhile ATRPs are known from different holometabolous insects but only a single ATRP could be identified from hemimetabolous insects [Paemen L, Tips A, Schoofs L, Proost P, Van Damme J, De Loof A. Lom-AG-myotropin: a novel myotropic peptide from the male accessory glands of Locusta migratoria. Peptides 1991;12:7-10.]. This means that the extensive analysis of neuropeptides from Leucophaea maderae and Periplaneta americana, which led to the discovery of many novel insect neuropeptides, did not result in the detection of any ATRP. In this study, we used another approach to find a cockroach ATRP by first identifying Manse-AT immunoreactive neurons in the terminal ganglion that can be stained by retrograde labeling and are suitable for dissection and subsequent mass spectrometric analysis. The peptidomic analysis of these putative ATRP neurons paved the way for the identification of the first cockroach ATRP. MALDI-TOF/TOF tandem mass spectrometry revealed a sequence identity with Locmi-AG-MT-1 which classifies this ATRP as a highly conserved neuropeptide. A mass spectrometric screening of the nervous system allowed the detection of ATRP-ion signals in different parts of the CNS of P. americana as well as L. maderae. The data obtained in this study will be incorporated in a map of peptidergic neurons from the CNS of the American cockroach, P. americana.

  15. Increased Protein Structural Resolution from Diethylpyrocarbonate-based Covalent Labeling and Mass Spectrometric Detection

    NASA Astrophysics Data System (ADS)

    Zhou, Yuping; Vachet, Richard W.

    2012-04-01

    Covalent labeling and mass spectrometry are seeing increased use together as a way to obtain insight into the 3-dimensional structure of proteins and protein complexes. Several amino acid specific (e.g., diethylpyrocarbonate) and non-specific (e.g., hydroxyl radicals) labeling reagents are available for this purpose. Diethylpyrocarbonate (DEPC) is a promising labeling reagent because it can potentially probe up to 30% of the residues in the average protein and gives only one reaction product, thereby facilitating mass spectrometric analysis. It was recently reported, though, that DEPC modifications are labile for some amino acids. Here, we show that label loss is more significant and widespread than previously thought, especially for Ser, Thr, Tyr, and His residues, when relatively long protein digestion times are used. Such label loss ultimately decreases the amount of protein structural information that is obtainable with this reagent. We find, however, that the number of DEPC modified residues and, thus, protein structural information, can be significantly increased by decreasing the time between the covalent labeling reaction and the mass spectrometric analysis. This is most effectively accomplished using short (e.g., 2 h) proteolytic digestions with enzymes such as immobilized chymotrypsin or Glu-C rather than using methods (e.g., microwave or ultrasonic irradiation) that accelerate proteolysis in other ways. Using short digestion times, we show that the percentage of solvent accessible residues that can be modified by DEPC increases from 44% to 67% for cytochrome c, 35% to 81% for myoglobin, and 76% to 95% for β-2-microglobulin. In effect, these increased numbers of modified residues improve the protein structural resolution available from this covalent labeling method. Compared with typical overnight digestion conditions, the short digestion times decrease the average distance between modified residues from 11 to 7 Å for myoglobin, 13 to 10 Å for

  16. Method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation in conjunction with mass spectrometric analysis

    DOEpatents

    Laskin, Julia [Richland, WA; Futrell, Jean H [Richland, WA

    2008-04-29

    The invention relates to a method and apparatus for enhanced sequencing of complex molecules using surface-induced dissociation (SID) in conjunction with mass spectrometric analysis. Results demonstrate formation of a wide distribution of structure-specific fragments having wide sequence coverage useful for sequencing and identifying the complex molecules.

  17. Spark-source mass spectrometric assessment of silicon concentrations in silicon-doped gallium arsenide single crystals.

    PubMed

    Wiedemann, B; Meyer, J D; Jockel, D; Freyhardt, H C; Birkmann, B; Müller, G

    2001-07-01

    The spark-source mass spectrometric assessment of silicon concentrations in silicon-doped vertical-gradient-freeze gallium arsenide is presented. The silicon concentrations determined are compared with the charge-carrier densities measured by means of the Hall effect with van der Pauw symmetry along the axis of a single crystal.

  18. Differentiation of whole grain and refined wheat (T. aestivum) flour using a fuzzy mass spectrometric fingerprinting and chemometric approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A fuzzy mass spectrometric (MS) fingerprinting method combined with chemometric analysis was established to provide rapid discrimination between whole grain and refined wheat flour. Twenty one samples, including thirteen samples from three cultivars and eight from local grocery store, were studied....

  19. XMS: Cross-Platform Normalization Method for Multimodal Mass Spectrometric Tissue Profiling

    NASA Astrophysics Data System (ADS)

    Golf, Ottmar; Muirhead, Laura J.; Speller, Abigail; Balog, Júlia; Abbassi-Ghadi, Nima; Kumar, Sacheen; Mróz, Anna; Veselkov, Kirill; Takáts, Zoltán

    2015-01-01

    Here we present a proof of concept cross-platform normalization approach to convert raw mass spectra acquired by distinct desorption ionization methods and/or instrumental setups to cross-platform normalized analyte profiles. The initial step of the workflow is database driven peak annotation followed by summarization of peak intensities of different ions from the same molecule. The resulting compound-intensity spectra are adjusted to a method-independent intensity scale by using predetermined, compound-specific normalization factors. The method is based on the assumption that distinct MS-based platforms capture a similar set of chemical species in a biological sample, though these species may exhibit platform-specific molecular ion intensity distribution patterns. The method was validated on two sample sets of (1) porcine tissue analyzed by laser desorption ionization (LDI), desorption electrospray ionization (DESI), and rapid evaporative ionization mass spectrometric (REIMS) in combination with Fourier transformation-based mass spectrometry; and (2) healthy/cancerous colorectal tissue analyzed by DESI and REIMS with the latter being combined with time-of-flight mass spectrometry. We demonstrate the capacity of our method to reduce MS-platform specific variation resulting in (1) high inter-platform concordance coefficients of analyte intensities; (2) clear principal component based clustering of analyte profiles according to histological tissue types, irrespective of the used desorption ionization technique or mass spectrometer; and (3) accurate "blind" classification of histologic tissue types using cross-platform normalized analyte profiles.

  20. Mass spectrometric imaging of flavonoid glycosides and biflavonoids in Ginkgo biloba L.

    PubMed

    Beck, Sebastian; Stengel, Julia

    2016-10-01

    Ginkgo biloba L. is known to be rich in flavonoids and flavonoid glycosides. However, the distribution within specific plant organs (e.g. within leaves) is not known. By using HPLC-MS and MS/MS we have identified a number of previously known G. biloba flavonoid glycosides and biflavonoids from leaves. Namely, kaempferol, quercetin, isorhamnetin, myricetin, laricitrin/mearnsetin and apigenin glycosides were identified. Furthermore, biflavonoids like ginkgetin/isoginkgetin were also detected. The application of MALDI mass spectrometric imaging, enabled the compilation of concentration profiles of flavonoid glycosides and biflavonoids in G. biloba L. leaves. Both, flavonoid glycosides and biflavonoids show a distinct distribution in leaf thin sections of G. biloba L.

  1. An accelerated mass spectrometric method for measuring myo-inositol in phosphatidylinositol in rat brain

    NASA Astrophysics Data System (ADS)

    Deutsch, Joseph; Ma, Kaizung; Rapoport, Stanley I.

    2006-03-01

    A fast and efficient chemical ionization mass spectrometric (CI-GC-MS) method for measuring myo-inositol in phosphatidylinositol (PtdIns) in rat brain has been developed. Previously, quantitation of PtdIns involved the release of the myo-inositol by two enzymatic reactions using phospholipase C and alkaline phosphatase. The hydrolytic action of these enzymes was replaced by using commercially available 48% hydrofluoric acid (HF) at 80 °C for 30 min. The process can be carried out on the crude Folch extract of brain phospholipids without prior thin layer chromatography (TLC) purification, thereby significantly increasing the speed of analysis. For quantification, unlabeled myo-inositol, labeled myo- and neo-inositol (internal standard) were converted to acetate derivatives and analyzed by CI-GC-MS.

  2. Regime Transition in Electromechanical Fluid Atomization and Implications to Analyte Ionization for Mass Spectrometric Analysis

    PubMed Central

    Forbes, Thomas P.; Degertekin, F. Levent; Fedorov, Andrei G.

    2015-01-01

    The physical processes governing the transition from purely mechanical ejection to electromechanical ejection to electrospraying are investigated through complementary scaling analysis and optical visualization. Experimental characterization and visualization are performed with the ultrasonically-driven array of micromachined ultrasonic electrospray (AMUSE) ion source to decouple the electrical and mechanical fields. A new dimensionless parameter, the Fenn number, is introduced to define a transition between the spray regimes, in terms of its dependence on the characteristic Strouhal number for the ejection process. A fundamental relationship between the Fenn and Strouhal numbers is theoretically derived and confirmed experimentally in spraying liquid electrolytes of different ionic strength subjected to a varying magnitude electric field. This relationship and the basic understanding of the charged droplet generation physics have direct implications on the optimal ionization efficiency and mass spectrometric response for different types of analytes. PMID:20729096

  3. Direct Electrospray Ionization Mass Spectrometric Profiling of Real-World Samples via a Solid Sampling Probe

    NASA Astrophysics Data System (ADS)

    Yu, Zhan; Chen, Lee Chuin; Mandal, Mridul Kanti; Yoshimura, Kentaro; Takeda, Sen; Hiraoka, Kenzo

    2013-10-01

    This study presents a novel direct analysis strategy for rapid mass spectrometric profiling of biochemicals in real-world samples via a direct sampling probe (DSP) without sample pretreatments. Chemical modification is applied to a disposable stainless steel acupuncture needle to enhance its surface area and hydrophilicity. After insertion into real-world samples, biofluid can be attached on the DSP surface. With the presence of a high DC voltage and solvent vapor condensing on the tip of the DSP, analyte can be dissolved and electrosprayed. The simplicity in design, versatility in application aspects, and other advantages such as low cost and disposability make this new method a competitive tool for direct analysis of real-world samples.

  4. Use of Composite Protein Database including Search Result Sequences for Mass Spectrometric Analysis of Cell Secretome

    PubMed Central

    Shin, Jihye; Kim, Gamin; Kabir, Mohammad Humayun; Park, Seong Jun; Lee, Seoung Taek; Lee, Cheolju

    2015-01-01

    Mass spectrometric (MS) data of human cell secretomes are usually run through the conventional human database for identification. However, the search may result in false identifications due to contamination of the secretome with fetal bovine serum (FBS) proteins. To overcome this challenge, here we provide a composite protein database including human as well as 199 FBS protein sequences for MS data search of human cell secretomes. Searching against the human-FBS database returned more reliable results with fewer false-positive and false-negative identifications compared to using either a human only database or a human-bovine database. Furthermore, the improved results validated our strategy without complex experiments like SILAC. We expect our strategy to improve the accuracy of human secreted protein identification and to also add value for general use. PMID:25822838

  5. 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.

  6. Regime transition in electromechanical fluid atomization and implications to analyte ionization for mass spectrometric analysis.

    PubMed

    Forbes, Thomas P; Degertekin, F Levent; Fedorov, Andrei G

    2010-11-01

    The physical processes governing the transition from purely mechanical ejection to electromechanical ejection to electrospraying are investigated through complementary scaling analysis and optical visualization. Experimental characterization and visualization are performed with the ultrasonically-driven array of micromachined ultrasonic electrospray (AMUSE) ion source to decouple the electrical and mechanical fields. A new dimensionless parameter, the Fenn number, is introduced to define a transition between the spray regimes, in terms of its dependence on the characteristic Strouhal number for the ejection process. A fundamental relationship between the Fenn and Strouhal numbers is theoretically derived and confirmed experimentally in spraying liquid electrolytes of different ionic strength subjected to a varying magnitude electric field. This relationship and the basic understanding of the charged droplet generation physics have direct implications on the optimal ionization efficiency and mass spectrometric response for different types of analytes.

  7. Liquid chromatography-mass spectrometric determination of losartan and its active metabolite on dried blood spots.

    PubMed

    Rao, R Nageswara; Raju, S Satyanarayana; Vali, R Mastan; Sankar, G Girija

    2012-08-01

    A simple and rapid quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous determination of losartan and its active metabolite, losartan carboxylic acid on rat dried blood spots was developed and validated as per regulatory guidelines. Losartan and its metabolite were extracted from dried blood spots using 50% aqueous methanol and separated on Waters XTerra(®) RP18 (250 mm × 4.6 mm, 5 μm) column using mobile phase composed of 40% acetonitrile and 60% aqueous ammonium acetate (10mM). The eluents were monitored using ESI tandem mass spectrometric detection with negative polarity in MRM mode using ion transitions m/z 421.2→179.0, m/z 435.3→157.0 and m/z 427.3→193.0 for losartan, losartan carboxylic acid and Irbesartan (internal standard), respectively. The method was validated over the linear range of 1-200 ng/mL and 5-1000 ng/mL with lower limits of quantification of 1.0 ng/mL and 5.0 ng/mL for losartan and losartan carboxylic acid, respectively. Inter and intra-day precision and accuracy (Bias) were below 5.96% and between -2.8 and 1.5%, respectively. The mean recoveries of the analytes from dried blood spots were between 89% and 97%. No significant carry over and matrix effects were observed. The stability of stock solution, whole blood, dried blood spot and processed samples were tested under different conditions and the results were found to be well within the acceptable limits. Additional validation parameters such as influence of hematocrit and spot volume were also evaluated and found to be well within the acceptable limits.

  8. iPE-MMR: An integrated approach to accurately assign monoisotopic precursor masses to tandem mass spectrometric data

    PubMed Central

    Jung, Hee-Jung; Purvine, Samuel O.; Kim, Hokeun; Petyuk, Vladislav A.; Hyung, Seok-Won; Monroe, Matthew E.; Mun, Dong-Gi; Kim, Kyong-Chul; Park, Jong-Moon; Kim, Su-Jin; Tolic, Nikola; Slysz, Gordon W.; Moore, Ronald J.; Zhao, Rui; Adkins, Joshua N.; Anderson, Gordon A.; Lee, Hookeun; Camp, David G.; Yu, Myeong-Hee; Smith, Richard D.; Lee, Sang-Won

    2010-01-01

    Accurate assignment of monoisotopic precursor masses to tandem mass spectrometric (MS/MS) data is a fundamental and critically important step for successful peptide identifications in mass spectrometry based proteomics. Here we describe an integrated approach that combines three previously reported methods of treating MS/MS data for precursor mass refinement. This combined method, “integrated Post-Experiment Monoisotopic Mass Refinement” (iPE-MMR), integrates steps: 1) generation of refined MS/MS data by DeconMSn; 2) additional refinement of the resultant MS/MS data by a modified version of PE-MMR; 3) elimination of systematic errors of precursor masses using DtaRefinery. iPE-MMR is the first method that utilizes all MS information from multiple MS scans of a precursor ion including multiple charge states, in an MS scan, to determine precursor mass. By combining these methods, iPE-MMR increases sensitivity in peptide identification and provides increased accuracy when applied to complex high-throughput proteomics data. PMID:20863060

  9. Gene analysis using mass spectrometric cleaved amplified polymorphic sequence (MS-CAPS) with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF).

    PubMed

    Kajiwara, Hideyuki

    2015-01-01

    Mass spectrometric cleaved amplified polymorphic sequence (MS-CAPS) is a method for detecting genes using a combination of short PCR and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). MS-CAPS can identify a single nucleotide polymorphism (SNP) in less than one hour and is suitable for plants, animals, bacteria, and food.

  10. Skeletal muscle fiber analysis by atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometric imaging at high mass and high spatial resolution.

    PubMed

    Tsai, Yu-Hsuan; Bhandari, Dhaka Ram; Garrett, Timothy J; Carter, Christy S; Spengler, Bernhard; Yost, Richard A

    2016-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers with various fiber types. These fibers can be classified into different classes based on their different characteristics. MALDI mass spectrometric imaging (MSI) has been applied to study and visualize different metabolomics profiles of different fiber types. Here, skeletal muscles were analyzed by atmospheric pressure scanning microprobe MALDI-MSI at high spatial and high mass resolution.

  11. A Portable and Autonomous Mass Spectrometric System for On-Site Environmental Gas Analysis.

    PubMed

    Brennwald, Matthias S; Schmidt, Mark; Oser, Julian; Kipfer, Rolf

    2016-12-20

    We developed a portable mass spectrometric system ("miniRuedi") for quantificaton of the partial pressures of He, Ne (in dry gas), Ar, Kr, N2, O2, CO2, and CH4 in gaseous and aqueous matrices in environmental systems with an analytical uncertainty of 1-3%. The miniRuedi does not require any purification or other preparation of the sampled gases and therefore allows maintenance-free and autonomous operation. The apparatus is most suitable for on-site gas analysis during field work and at remote locations due to its small size (60 cm × 40 cm × 14 cm), low weight (13 kg), and low power consumption (50 W). The gases are continuously sampled and transferred through a capillary pressure reduction system into a vacuum chamber, where they are analyzed using a quadrupole mass spectrometer with a time resolution of ≲1 min. The low gas consumption rate (<0.1 mL/min) minimizes interference with the natural mass balance of gases in environmental systems, and allows the unbiased quantification of dissolved-gas concentrations in water by gas/water equilibration using membrane contractors (gas-equilibrium membrane-inlet mass spectrometry, GE-MIMS). The performance of the miniRuedi is demonstrated in laboratory and field tests, and its utility is illustrated in field applications related to soil-gas formation, lake/atmosphere gas exchange, and seafloor gas emanations.

  12. Mass spectrometric characterization of the neuropeptidome of the ghost crab Ocypode ceratophthalma (Brachyura, Ocypodidae).

    PubMed

    Hui, Limei; D'Andrea, Brandon T; Jia, Chenxi; Liang, Zhidan; Christie, Andrew E; Li, Lingjun

    2013-04-01

    The horn-eyed ghost crab Ocypode ceratophthalma is a terrestrial brachyuran native to the Indo-Pacific region, including the islands of Hawaii. Here, multiple mass spectrometric platforms, including matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) and nanoflow liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (nanoLC-ESI-Q-TOF MS/MS), were used to characterize the neuropeptidome of this species. In total, 156 peptide paracrines/hormones, representing 15 peptide families, were identified from the O. ceratophthalma supraesophageal ganglion (brain), eyestalk ganglia, pericardial organ and/or sinus gland, including 59 neuropeptides de novo sequenced here for the first time. Among the de novo sequenced peptides were isoforms of A-type allatostatin, B-type allatostatin, FMRFamide-like peptide (FLP), orcokinin, orcomyotropin and RYamide. Of particular note, were several novel FLPs including DVRAPALRLRFamide, an isoform of short neuropeptide F, and NRSNLRFamide, the orcokinins NFDEIDRSGYGFV and DFDEIDRSSFGFH, which exhibit novel Y for F and D for N substitutions at positions 10 and 1, respectively, and FDAYTTGFGHS, a member of the orcomyotropin family exhibiting a novel Y for F substitution at position 4. Taken collectively, the set of peptides described here represents the largest number of neuropeptides thus far characterized via mass spectrometry from any single crustacean, and provides a framework for future investigations of the physiological roles played by these molecules in this species.

  13. Mass spectrometric techniques for characterizing low-molecular-weight resins used as paint varnishes.

    PubMed

    Bonaduce, I; Colombini, M P; Degano, I; Di Girolamo, F; La Nasa, J; Modugno, F; Orsini, S

    2013-01-01

    The molecular structure of three low-molecular-weight resins used as paint varnishes has been characterized by use of an approach based on three different mass spectrometric techniques. We investigated the ketone resin MS2A, the aldehyde resin Laropal A81, and the hydrocarbon resin Regalrez 1094, now commonly used in restoration. To date, the molecular structures of these resins have not been completely elucidated. To improve current knowledge of the chemical composition of these materials, information obtained by gas chromatography-mass spectrometry (GC/MS), pyrolysis-gas chromatography-mass spectrometry (Py/GC/MS), and electrospray ionization mass spectrometry (ESI-Q-ToF) was combined. Analysis, in solution, of the whole polymeric fraction of the resins by flow-injection ESI-Q-ToF, and of the non-polymeric fraction by GC-MS, enabled us to identify previously unreported features of the polymer structures. In addition, the Py-GC/MS profiles that we obtained will help to enhance the databases currently available in the literature. The proposed approach can be extended to other low-molecular-weight resins used as varnishes in conservation.

  14. Extraction and chromatography-mass spectrometric analysis of the active principles from selected Chinese herbs and other medicinal plants.

    PubMed

    Wang, Xiaosuo; Kapoor, Vimal; Smythe, George A

    2003-01-01

    Medicinal herbs have a long history of use in the practice of traditional Chinese medicine and a substantial body of evidence has, over recent decades, demonstrated a range of important pharmacological properties. Western biomedical researchers are examining not only the efficacy of the traditional herbal products but, through the use of a range of bioassays and analytical techniques, are developing improved methods to isolate and characterize active components. This review briefly describes the different extraction methodologies used in the preparation of herbal extracts and reviews the utility of chromatography-mass spectrometry for the analysis of their active components. In particular, applications of gas or liquid chromatography with mass spectrometry for the isolation and characterization of active components of ginseng are critically assessed. The analysis of toxic substances from herb extracts with mass spectrometric techniques is also discussed along with the potential for mass spectrometric methods to investigate the proteomics of herbal extracts.

  15. Mass spectrometric measurement of protein amide hydrogen exchange rates of apo- and holo-myoglobin.

    PubMed Central

    Johnson, R. S.; Walsh, K. A.

    1994-01-01

    Measurement of backbone amide hydrogen exchange rates can provide detailed information concerning protein structure, dynamics, and interactions. Although nuclear magnetic resonance is typically used to provide these data, its use is restricted to lower molecular weight proteins that are soluble at millimolar concentrations. Not subject to these limitations is a mass spectrometric approach for measuring deuterium incorporation into proteins that are subsequently proteolyzed by pepsin; the resulting peptide masses are measured using a flowing-fast atom bombardment ionization source (Zhang Z, Smith DL, 1993, Protein Sci 2:522-531). In the current study, amide deuterium incorporation for intact apo- and holo-myoglobin was measured using liquid chromatography coupled directly to an electrospray ionization (LC/MS) source. Electrospray ionization provided a more complete coverage of the protein sequence and permitted the measurement of deuterium incorporation into intact proteins. Tandem mass spectrometry was used to rapidly identify the peptic peptides. It was found that within 30 s, the amides in apo-myoglobin were 47% deuterated, whereas holo-myoglobin was 12% deuterated. Peptic digestion and LC/MS demonstrated that regions represented by peptic peptides encompassing positions 1-7, 12-29, and 110-134 were not significantly altered by removal of the heme. Likewise, destabilized regions were identified within positions 33-106 and 138-153. PMID:7756994

  16. Characterisation of natural indigo and shellfish purple by mass spectrometric techniques.

    PubMed

    Andreotti, Alessia; Bonaduce, Ilaria; Colombini, Maria Perla; Ribechini, Erika

    2004-01-01

    Two analytical methods based on mass spectrometry were used in the characterisation of constituents of natural indigo prepared from the leaves of Indigofera tinctoria, and of shellfish purple prepared from the hypobranchial glandular secretions of Murex trunculus, following old recipes. On-line pyrolysis gas chromatography in the presence of hexamethyldisilazane followed by mass spectrometric analysis (Py-silylation/GC/MS), and direct exposure mass spectrometry (DE-MS), were used. Extensive fragmentation of indigoid dyes was obtained by Py-silylation/GC/MS. The following molecular markers were highlighted, which are useful for identification purposes: 1,2-dihydro-3H-indol-3-one for indigoid dyes, 1,3-dihydro-2H-indol-2-one for indirubine, and 6-bromo-1,2-dihydro-3H-indol-3-one for shellfish purple. Using DE-MS, 6,6'dibromoindigotine, monobromoindigotine and indigotine were identified as the main components, and the presence of tyrindoxyl, one of the dye precursors, was also assessed.

  17. Gas chromatographic and mass spectrometric analysis of polychlorinated biphenyls in human placenta and cord blood

    SciTech Connect

    Ando, M.; Saito, H.; Wakisaka, I.

    1986-10-01

    Gas chromatographic and mass spectrometric analyses of polychlorinated biphenyls (PCBs) in placenta, maternal blood, cord blood, and milk were carried out. Trichlorobiphenyl, tetrachlorobiphenyl, pentachlorobiphenyls, and hexachlorobiphenyls were identified by the mass chromatogram and the mass spectra. Some minor peaks of PCBs were identified by gas chromatography. The relationship between the PCB concentration in placenta and that in milk is different in each PCB congener. The higher the chlorine content of the PCB congener, the more significant the correlation. No significant but a low negative correlation exists between the concentration of some PCB congeners in the placenta and that in cord blood. On the other hand, a significant linear correlation exists between the concentration of hexachlorobenzene in the placenta and that in cord blood. The transplacental transport of each PCB congener varied depending upon its chemical nature. Trichlorobiphenyl and tetrachlorobiphenyl were more transferable than hexachlorobiphenyls. The results show that the placenta and cord blood are useful human samples to analyze the body burden of environmental pollutants and to estimate their transfer from mother to fetus.

  18. Mass spectrometric survey of peptides in cephalopods with an emphasis on the FMRFamide-related peptides.

    PubMed

    Sweedler, J V; Li, L; Floyd, P; Gilly, W

    2000-12-01

    A matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) survey of the major peptides in the stellar, fin and pallial nerves and the posterior chromatophore lobe of the cephalopods Sepia officinalis, Loligo opalescens and Dosidicus gigas has been performed. Although a large number of putative peptides are distinct among the three species, several molecular masses are conserved. In addition to peptides, characterization of the lipid content of the nerves is reported, and these lipid peaks account for many of the lower molecular masses observed. One conserved set of peaks corresponds to the FMRFamide-related peptides (FRPs). The Loligo opalescens FMRFa gene has been sequenced. It encodes a 331 amino acid residue prohormone that is processed into 14 FRPs, which are both predicted by the nucleotide sequence and confirmed by MALDI MS. The FRPs predicted by this gene (FMRFa, FLRFa/FIRFa and ALSGDAFLRFa) are observed in all three species, indicating that members of this peptide family are highly conserved across cephalopods.

  19. Electrothermal atomic absorption spectrometric determination of total and hexavalent chromium in atmospheric aerosols.

    PubMed

    Mandiwana, Khakhathi L; Panichev, Nikolay; Resane, Tabby

    2006-08-21

    A method was developed which allow separate determination of Cr(VI) and total Cr from the same minute sample of atmospheric aerosols. Cr(VI) was leached was with 0.1M Na(2)CO(3) and the total Cr concentrations were determined after acid digestion. The method was validated by the analysis of certified reference materials, CRM 545, Mess-3 and Pacs-2 with good agreement between certified and found values. Cr concentrations in air samples taken around the chromium smelter show concentrations that exceed the maximum allowed levels in 8h with higher values closer to the smelter. The limit of detection (LOD) of the method for Cr(VI) determination in air samples was found to be 0.2 ng m(-3), i.e. lower than offered by the commonly preferred spectrophotometric and colorimetric techniques.

  20. Targeting prohibited substances in doping control blood samples by means of chromatographic-mass spectrometric methods.

    PubMed

    Thevis, Mario; Thomas, Andreas; Schänzer, Wilhelm

    2013-12-01

    Urine samples have been the predominant matrix for doping controls for several decades. However, owing to the complementary information provided by blood (as well as serum or plasma and dried blood spots (DBS)), the benefits of its analysis have resulted in continuously increasing appreciation by anti-doping authorities. On the one hand, blood samples allow for the detection of various different methods of blood doping and the abuse of erythropoiesis-stimulating agents (ESAs) via the Athlete Biological Passport; on the other hand, targeted and non-targeted drug detection by means of chromatographic-mass spectrometric methods represents an important tool to increase doping control frequencies out-of-competition and to determine drug concentrations particularly in in-competition scenarios. Moreover, blood analysis seldom requires in-depth knowledge of drug metabolism, and the intact substance rather than potentially unknown or assumed metabolic products can be targeted. In this review, the recent developments in human sports drug testing concerning mass spectrometry-based techniques for qualitative and quantitative analyses of therapeutics and emerging drug candidates are summarized and reviewed. The analytical methods include both low and high molecular mass compounds (e.g., anabolic agents, stimulants, metabolic modulators, peptide hormones, and small interfering RNA (siRNA)) determined from serum, plasma, and DBS using state-of-the-art instrumentation such as liquid chromatography (LC)-high resolution/high accuracy (tandem) mass spectrometry (LC-HRMS), LC-low resolution tandem mass spectrometry (LC-MS/MS), and gas chromatography-mass spectrometry (GC-MS).

  1. Chromatographic tandam mass spectrometric detection of papaverine and its major metabolites in rat urine

    NASA Astrophysics Data System (ADS)

    Peng, Zhihong; Song, Wei; Han, Fengmei; Chen, Huaixia; Zhu, Mingming; Chen, Yong

    2007-10-01

    A rapid, sensitive and specific liquid chromatographic-electrospray ionization (ESI) tandem ion trap mass spectrometric method has been developed for identification of papaverine and its metabolites in rat urine. Six healthy rats were administrated a single dose (100 mg/kg) of papaverine by oral gavage. The urine were sampled for 0-24 h and purified by using a C18 solid-phase extraction cartridge, then the purified urine samples were separated on a reversed-phase C18 column using methanol/2 mmol/L ammonium acetate (70:30, v/v, adjusted to pH 3.5 with formic acid) as mobile phase and detected by an on-line MS detector. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular mass ([Delta]m) and full scan MSn spectra with those of the parent drug. The results indicated that there were 14 metabolites in rat urine, such as de-methoxyl, hydroxyl, glucuronide and sulfate conjugated metabolites and so on. All these metabolites were reported for the first time.

  2. Mass Spectrometric Imaging of Red Fluorescent Protein in Breast Tumor Xenografts

    NASA Astrophysics Data System (ADS)

    Chughtai, Kamila; Jiang, Lu; Post, Harm; Winnard, Paul T.; Greenwood, Tiffany R.; Raman, Venu; Bhujwalla, Zaver M.; Heeren, Ron M. A.; Glunde, Kristine

    2013-05-01

    Mass spectrometric imaging (MSI) in combination with electrospray mass spectrometry (ESI-MS) is a powerful technique for visualization and identification of a variety of different biomolecules directly from thin tissue sections. As commonly used tools for molecular reporting, fluorescent proteins are molecular reporter tools that have enabled the elucidation of a multitude of biological pathways and processes. To combine these two approaches, we have performed targeted MS analysis and MALDI-MSI visualization of a tandem dimer (td)Tomato red fluorescent protein, which was expressed exclusively in the hypoxic regions of a breast tumor xenograft model. For the first time, a fluorescent protein has been visualized by both optical microscopy and MALDI-MSI. Visualization of tdTomato by MALDI-MSI directly from breast tumor tissue sections will allow us to simultaneously detect and subsequently identify novel molecules present in hypoxic regions of the tumor. MS and MALDI-MSI of fluorescent proteins, as exemplified in our study, is useful for studies in which the advantages of MS and MSI will benefit from the combination with molecular approaches that use fluorescent proteins as reporters.

  3. Mass Spectrometric Study on Sodium Ion Induced Central Nucleotide Deletion in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Flosadóttir, Helga Dögg; Gíslason, Kristmann; Sigurdsson, Snorri Thor; Ingólfsson, Oddur

    2012-04-01

    We report a mass spectrometric study on sodium ion induced central nucleotide deletion from protonated oligonucleotides (ONTs) and the concurrent recombination of the terminal nucleotides. To shed some light on the mechanism behind this intriguing fragmentation channel, we have studied the metastable decay of a number of different protonated hexameric and octameric oligonucleotides with 0-6 and 0-8 of their exchangeable protons replaced with sodium ions, respectively. In selected cases, we have also studied the further fragmentation of the parent ions after initial base loss. Our findings are concurrent with a reaction mechanism where the initial step is the elimination of a protonated, high proton affinity (PA) base from the center of the ONTs. This is followed by an elimination of a (next neighbour) nucleotide that contains a second high PA base and the concurrent recombination of the terminal nucleotides. To our knowledge, such central nucleotide deletion in the gas phase has only been reported in one previous study (Flosadóttir et al., J. Am. Soc. Mass Spectrom 20:689-696, 2009), and this is the first systematic approach to understand the mechanism behind this channel.

  4. The usefulness of hydrazine derivatives for mass spectrometric analysis of carbohydrates.

    PubMed

    Lattová, Erika; Perreault, Hélène

    2013-01-01

    Over the last years, extensive studies have evaluated glycans from different biological samples and validated the importance of glycosylation as one of the most important post-translational modifications of proteins. Although a number of new methods for carbohydrate analysis have been published and there has been significant progress in their identification, the development of new approaches to study these biomolecules and understand their role in living systems are still vivid challenges that intrigue glycobiologists. In the last decade, the success in analyses of oligosaccharides has been driven mainly by the development of innovative, highly sensitive mass spectrometry techniques. For enhanced mass spectrometry detection, carbohydrate molecules are often derivatized. Besides, the type of labeling can influence the fragmentation pattern and make the structural analysis less complicated. In this regard, in 2003 we introduced the low scale, simple non-reductive tagging of glycans employing phenylhydrazine (PHN) as the derivatizing reagent. PHN-labeled glycans showed increased detection and as reported previously they can be analyzed by HPLC, ESI, or MALDI immediately after derivatization. Under tandem mass spectrometry conditions, PHN-derivatives produced useful data for the structural elucidation of oligosaccharides. This approach of analysis has helped to reveal new isomeric structures for glycans of known/unknown composition and has been successfully applied for the profiling of N-glycans obtained from serum samples and cancer cells. The efficacy of this labeling has also been evaluated for different substituted hydrazine reagents. This review summarizes all types of reducing-end labeling based on hydrazone-linkage that have been used for mass spectrometric analyses of oligosaccharides. This review is also aimed at correcting some past misconceptions or interpretations reported in the literature.

  5. Workplace aerosol mass concentration measurement using optical particle counters.

    PubMed

    Görner, Peter; Simon, Xavier; Bémer, Denis; Lidén, Göran

    2012-02-01

    Direct-reading aerosol measurement usually uses the optical properties of airborne particles to detect and measure particle concentration. In the case of occupational hygiene, mass concentration measurement is often required. Two aerosol monitoring methods are based on the principle of light scattering: optical particle counting (OPC) and photometry. The former analyses the light scattered by a single particle, the latter by a cloud of particles. Both methods need calibration to transform the quantity of scattered light detected into particle concentration. Photometers are simpler to use and can be directly calibrated to measure mass concentration. However, their response varies not only with aerosol concentration but also with particle size distribution, which frequently contributes to biased measurement. Optical particle counters directly measure the particle number concentration and particle size that allows assessment of the particle mass provided the particles are spherical and of known density. An integrating algorithm is used to calculate the mass concentration of any conventional health-related aerosol fraction. The concentrations calculated thus have been compared with simultaneous measurements by conventional gravimetric sampling to check the possibility of field OPC calibration with real workplace aerosols with a view to further monitoring particle mass concentration. Aerosol concentrations were measured in the food industry using the OPC GRIMM® 1.108 and the CIP 10-Inhalable and CIP 10-Respirable (ARELCO®) aerosol samplers while meat sausages were being brushed and coated with calcium carbonate. Previously, the original OPC inlet had been adapted to sample inhalable aerosol. A mixed aerosol of calcium carbonate and fungi spores was present in the workplace. The OPC particle-size distribution and an estimated average particle density of both aerosol components were used to calculate the mass concentration. The inhalable and respirable aerosol fractions

  6. Mass spectrometric identification of an azobenzene derivative produced by smectite-catalyzed conversion of 3-amino-4-hydroxyphenylarsonic acid

    USGS Publications Warehouse

    Wershaw, R. L.; Rutherford, D.W.; Rostad, C.E.; Garbarino, J.R.; Ferrer, I.; Kennedy, K.R.; Momplaisir, G.-M.; Grange, A.

    2003-01-01

    The compound 3-amino-4-hydroxyphenylarsonic acid (3-amino-HPAA) reacts with smectite to form a soluble azobenzene arsonic acid compound. This reaction is of particular interest because it provides a possible mechanism for the formation of a new type of arsenic compound in natural water systems. 3-Amino-HPAA is a degradation product excreted by chickens that are fed rations amended with roxarsone. Roxarsone is used to control coccidial intestinal parasites in most of the broiler chickens grown in the United States. The structure of the azobenzene arsonic acid compound was first inferred from negative-ion and positive-ion low-resolution mass-spectrometric analyses of the supernatant of the smectite suspension. Elemental composition of the parent ion determined by high-resolution positive-ion mass spectrometric measurements was consistent with the proposed structure of the azobenzene arsonic acid compound. Published by Elsevier Science B.V.

  7. Measurement of mass distribution of chemical species in aerosol particles

    NASA Technical Reports Server (NTRS)

    Sinha, M. P.; Friedlander, S. K.

    1984-01-01

    Aerosols may be generated through the nebulizing of solutions and the evaporation of their solvent, leaving the dry solute particles. Attention is presently given to a method for the direct determination of the masses of chemical species in individual aerosol particles on a continuous, real-time basis, using mass spectrometry. After the aerosol particles are introduced into the ion source of a quadrupole mass spectrometer, the particles impinge on a hot rhenium filament in the mass spectrometer's ion source. The resulting vapor plume is ionized by electron bombardment, and a pulse of ions is generated by each particle. The intensities of different masses in the ion pulses can then be measured by the mass spectrometer.

  8. Dependence of mass spectrometric fragmentation on the bromine substitution pattern of polybrominated diphenyl ethers.

    PubMed

    Wei, Hua; Zhang, Siyu; Wang, Yawei; Wang, Ying; Li, An; Negrusz, Adam; Yu, Gang

    2014-06-01

    This study investigates the link between the bromine substitution and the mass spectrometric fragmentation of polybrominated diphenyl ethers (PBDEs). The mass spectra of 180 PBDEs were obtained in both electron impact (EI) and electron capture negative ionization (ECNI) modes using a single quadrupole mass spectrometer (MS) as well as EI using a tandem MS (MS/MS). The major ions are M(+), [M-2Br](+), [M-2Br](2+) and [M-nBr-28](+) in EI, and Br(-), [HBr2](-) and [C6BrnO](-) in ECNI. In EI-MS, congeners without ortho bromine or having 2,3 substitution on one ring and no ortho bromines on the other were more robust than the others in each homolog. These congeners generated low [M-2Br](+) but relatively high [M-2Br](2+) in EI-MS and negligible [HBr2](-) in ECNI-MS. In EI-MS/MS, the molecular ions of these congeners required higher collision energy to debrominate, and produced additional ions of [M-nBr](+) and [M-nBr-28](+). Full ortho substitution promotes C-O cleavage forming [C6BrnO](-) in ECNI for congeners with >5 bromines. The relationship between the abundance of M(+) and collision energy of the EI-MS/MS was well characterized with a logistic regression model. Principle component analysis found associations between the inflection point collision energy and a few molecular descriptors. Quantum chemistry simulations revealed different EI-induced fragmentation mechanisms among four dibrominated congeners, supporting the hypothesized formation of a stable dibenzofuran-like intermediate during the fragmentation of some congeners but not of others.

  9. Gas chromatographic/mass spectrometric determination of daminozide in high protein food products.

    PubMed

    Conditt, M K; Baumgardner, J R; Hellmann, L M

    1988-01-01

    A gas chromatographic/mass spectrometric (GC/MS) method for determining daminozide in high protein products has been developed. Daminozide is hydrolyzed in the presence of a strong base to form unsymmetrical dimethylhydrazine (UDMH) which is then distilled from the food matrix. A stable derivative is formed by reacting UDMH with salicyladehyde to form salicyaldehyde dimethylhydrazone. This derivative is separated and quantitated by GC/MS using selected ion monitoring (SIM) of key ions in the fragmentation pattern: m/z 164 (molecular ion of hydrazone) and m/z 120 (C7H6ON). An internal standard, 4-nitroanisole, is monitored at m/z 153 (molecular ion) and m/z 123 (C6H5O2N). The limit of detection is 0.01 ppm daminozide in a 50 g sample; however, because of variation at low levels, the limit of quantitation is 0.1 ppm. Recoveries are 90% or greater from peanuts and peanut butter spiked at the 0.1-2 ppm level. Reproducibility of the method depends on the food matrix and is 26% RSD in the worst case. Data are compared for the GC/MS method and the official EPA colorimetric procedure. Results showed a high bias in the colorimetric method, especially when roasted peanut products were analyzed.

  10. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals.

    PubMed

    Edwards, R L; Chen, J H; Ku, T L; Wasserburg, G J

    1987-06-19

    The development of mass spectrometric techniques for determination of (230)Th abundance has made it possible to reduce analytical errors in (238)U-(234)U-(230)Th dating of corals even with very small samples. Samples of 6 x 10(8) atoms of (230)Th can be measured to an accuracy of +/-3 percent (2sigma) and 3 x 10(10) atoms of (230)Th can be measured to an accuracy of +/-0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to (14)C dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly postdate, the summer solar insolation high at 65 degrees N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  11. Analysis of Endocrine Disrupting Pesticides by Capillary GC with Mass Spectrometric Detection

    PubMed Central

    Matisová, Eva; Hrouzková, Svetlana

    2012-01-01

    Endocrine disrupting chemicals, among them many pesticides, alter the normal functioning of the endocrine system of both wildlife and humans at very low concentration levels. Therefore, the importance of method development for their analysis in food and the environment is increasing. This also covers contributions in the field of ultra-trace analysis of multicomponent mixtures of organic pollutants in complex matrices. With this fact conventional capillary gas chromatography (CGC) and fast CGC with mass spectrometric detection (MS) has acquired a real importance in the analysis of endocrine disrupting pesticide (EDP) residues. This paper provides an overview of GC methods, including sample preparation steps, for analysis of EDPs in a variety of matrices at ultra-trace concentration levels. Emphasis is put on separation method, mode of MS detection and ionization and obtained limits of detection and quantification. Analysis time is one of the most important aspects that should be considered in the choice of analytical methods for routine analysis. Therefore, the benefits of developed fast GC methods are important. PMID:23202677

  12. Gas chromatography-mass spectrometric method for metabolic profiling of tobacco leaves.

    PubMed

    Li, Yong; Pang, Tao; Li, Yanli; Wang, Xiaolin; Li, Qinghua; Lu, Xin; Xu, Guowang

    2011-06-01

    A gas chromatography-mass spectrometric method was developed for profiling of tobacco leaves. The differentiation among tobacco leaves planted in two different regions was investigated. Prior to analysis, the extraction solvent formulation was optimized and a combination of water, methanol and acetonitrile with a volume ratio of 3:1:1 was found to be optimal. The reproducibility of the method was satisfactory. Kendall tau-b rank correlation coefficients were equal to 1 (p<0.05) for 82% of the resolved peaks (up to 95% of the overall peak areas), indicating the good response correlation. Forty-four compounds including 9 saccharides, 9 alcohols, 9 amino acids, 16 organic acids and phosphoric acid were identified based on standard compounds. The method was successfully applied for profiling of tobacco leaves from Zimbabwe and Yunnan of China. Our result revealed that levels of saccharides and their derivatives including xylose, ribose, fructose, glucose, turanose, xylitol and glyceric acid were more abundant while sucrose, glucitol and D-gluconic acid were less abundant in tobacco leaves from Yunnan as compared to those from Zimbabwe. Amino acids such as L-alanine, L-tyrosine and L-threonine were found to be richer in Zimbabwe tobacco than in Yunnan tobacco.

  13. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin.

    PubMed

    Hulst, Albert G; Verstappen, Daan R W; van der Riet-Van Oeveren, Debora; Vermeulen, Nico P E; Noort, Daan

    2015-07-25

    In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed on the ε-amino group of lysine. In addition, numerous modified tryptic keratin fragments were identified, demonstrating rather random lysine modification. Interestingly, preliminary experiments demonstrate that in case of MDI a similar lysine di-adduct was formed with lung elastin. Our data support the hypothesis that skin sensitization through antigenic modifications of skin proteins by isocyanates could play a role in occupational isocyanate-induced asthma. It is further envisaged that the elucidated adducts will also have great potential for use as biomarkers to assess skin exposure to isocyanates. Advantageously, the various lysine adducts display the presence of a characteristic daughter fragment at m/z 173.1 [lysine-NCO](+), enabling generic and rapid screening for exposure to isocyanates.

  14. Chromatographic and mass spectrometric techniques in studies on oxidative stress in autism.

    PubMed

    Kałużna-Czaplińska, Joanna; Jóźwik-Pruska, Jagoda

    2016-04-15

    Healthy body is characterized by the presence of a dynamic and balanced equilibrium between the production of reactive oxygen species (ROS) and the antioxidant capacity. In oxidative stress this balance is switched to reactions of oxidation leading to increased production of ROS, exceeding the capacity of physiological antioxidant systems. Oxidative stress is known to be linked to many disturbances, disorders and diseases. One of these is the autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder manifested by abnormalities in social communication and interaction, as well as by occurrence of repetitive, restricted patterns of behavior or activities. It is believed that adequate knowledge about the oxidative stress biomarkers and the possibility of their reliable measuring could be useful in broadening knowledge on various diseases including ASD. A high number of compounds have been proposed as biomarkers of oxidative stress. Some of these are connected with the severity of ASD. The present review gives a summary of the chromatographic techniques used for the determination of biomarkers for oxidative stress in autism, and of other compounds important in this context. The first part of the review focuses on the correlation between oxidative stress and autism. The second part describes applications of chromatographic and mass spectrometric methods to the analysis of different metabolites connected with oxidative stress in biological fluids of autistic children. Advantages as well as disadvantages of the application of these methods for the analysis of different types of oxidative stress biomarkers are discussed.

  15. Enantiospecific gas chromatographic-mass spectrometric analysis of urinary methylphenidate: implications for phenotyping.

    PubMed

    LeVasseur, Natalie L; Zhu, Hao-Jie; Markowitz, John S; DeVane, C Lindsay; Patrick, Kennerly S

    2008-02-01

    A chiral derivatization gas chromatographic-mass spectrometric (GC-MS) method for urine methylphenidate (MPH) analysis was developed and validated to investigate preliminary findings regarding a novel MPH poor metabolizer (PM). Detection was by electron impact (EI) ionization-selected ion monitoring of the N-trifluoroacetylprolylpiperidinium fragments from MPH and the piperidine-deuterated MPH internal standard. The PM eliminated approximately 70 times more l-MPH in urine (9% of the dose over 0-10h), and approximately 5 times more of the d-isomer (10% of the dose), than the mean values determined from 10 normal metabolizers of MPH. Only minor amounts of the metabolite p-hydroxy-MPH were found in the urine of both the PM and normal metabolizers, while the concentration of MPH lactam was not high enough to be detectable. The described method indirectly gauges the functional carboxylesterase-1 status of patients receiving MPH based on the evaluation of relative urine concentrations of d-MPH:l-MPH. Clinical implications concerning rational drug selection for an identified or suspected MPH PM are discussed.

  16. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals

    SciTech Connect

    Edwards, R.L.; Chen, J.H.; Ku, T.L.; Wasserburg, G.J.

    1987-06-19

    The development of mass spectrometric techniques for determination of STTh abundance has made it possible to reduce analytical errors in STYU-STUU-STTh dating of corals even with very small samples. Samples of 6 x 10Y atoms of STTh can be measured to an accuracy of +/- 3% (2sigma) and 3 x 10 atoms of STTh can be measured to an accuracy of +/- 0.2%. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to UC dating. The precision should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly postdate, the summer solar insolation high at 65N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  17. Mass spectrometric identification of boric acid in fluid inclusions in pegmatite minerals

    SciTech Connect

    Williams, A.E.; Taylor, M.C.

    1996-09-01

    Direct, on-line mass spectrometric analyses were performed on volatiles released from microscopic fluid inclusions in quartz, feldspar, and tourmaline from the miarolitic Belo Horizonte No. 1 pegmatite in the San Jacinto district, and Himalaya pegmatite dike system in the Mesa Grande district of southern California. These analyses are the first inclusion volatile studies to indicate the presence of significant and variable concentrations of B compounds in pegmatite formation fluids. Boron appears as boric acid B(OH){sub 3}, which is found at levels ranging from less than detection limit (<10{sup {minus}7} mole fraction) to as high as 10{sup {minus}4} mole fraction. High B concentrations are seen in inclusion fluids from miarolite filling quartz, cleavelandite variety albite feldspar, and schorl tourmaline from the Belo Horizonte No. 1, while negligible amounts appear in late-stage green/pink-zoned gem elbaite tourmalines from that mine. Fluid inclusions in quartz, as well as grey and pink tourmaline form the miarolites in the Himalaya mine, have undetectable levels of B compounds. In addition to confirming the presence of very high boric acid concentrations in some pegmatite forming solutions, observations of large variations in abundance may provide new constraints on fluid chemical evolution trends during the genesis of these regionally and paragenetically complex gem deposits. 38 refs., 6 figs., 1 tab.

  18. A fast sampling device for the mass spectrometric analysis of liquid rocket engine exhaust

    NASA Technical Reports Server (NTRS)

    Ryason, P. R.

    1975-01-01

    The design of a device to obtain compositional data on rocket exhaust by direct sampling of reactive flow exhausts into a mass spectrometer is presented. Sampling at three stages differing in pressure and orifice angle and diameter is possible. Results of calibration with pure gases and gas mixtures are erratic and of unknown accuracy for H2, limiting the usefulness of the apparatus for determining oxidizer/fuel ratios from combustion product analysis. Deposition effects are discussed, and data obtained from rocket exhaust spectra are analyzed to give O/F ratios and mixture ratio distribution. The O/F ratio determined spectrometrically is insufficiently accurate for quantitative comparison with cold flow data. However, a criterion for operating conditions with improved mixing of fuel and oxidizer which is consistent with cold flow results may be obtained by inspection of contour plots. A chemical inefficiency in the combustion process when oxidizer is in excess is observed from reactive flow measurements. Present results were obtained with N2O4/N2H4 propellants.

  19. Mass Spectrometric and Spectrofluorometric Studies of the Interaction of Aristolochic Acids with Proteins

    NASA Astrophysics Data System (ADS)

    Li, Weiwei; Hu, Qin; Chan, Wan

    2015-10-01

    Aristolochic acid (AA) is a potent carcinogen and nephrotoxin and is associated with the development of “Chinese herb nephropathy” and Balkan endemic nephropathy. Despite decades of research, the specific mechanism of the observed nephrotoxicity has remained elusive and the potential effects on proteins due to the observed toxicity of AA are not well-understood. To better understand the pharmacotoxicological features of AA, we investigated the non-covalent interactions of AA with proteins. The protein-binding properties of AA with bovine serum albumin (BSA) and lysozyme were characterized using spectrofluorometric and mass spectrometric (MS) techniques. Moreover, the protein-AA complexes were clearly identified by high-resolution MS analyses. To the best of our knowledge, this is the first direct evidence of non-covalently bound protein-AA complexes. An analysis of the spectrofluorometric data by a modified Stern-Volmer plot model also revealed that both aristolochic acid I (AAI) and aristolochic acid II (AAII) were bound to BSA and lysozyme in 1:1 stoichiometries. A significantly stronger protein binding property was observed in AAII than in AAI as evidenced by the spectrofluorometric and MS analyses, which may explain the observed higher mutagenicity of AAII.

  20. Liquid chromatography/mass spectrometric determination of patulin in apple juice using atmospheric pressure photoionization.

    PubMed

    Takino, Masahiko; Daishima, Shigeki; Nakahara, Taketoshi

    2003-01-01

    This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) technique for the liquid chromatography/mass spectrometric (LC/MS) determination of patulin in clear apple juice. A column switching technique for on-line extraction of clear apple juice was developed. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for both APCI and APPI. The results indicated that APPI provides lower chemical noise and signal suppression in comparison with APCI. The linear range for patulin in apple juice (correlation coefficient >0.999) was 0.2-100 ng mL(-1). Mean recoveries of patulin in three apple juices ranged from 94.5 to 103.2%, and the limit of detection (S/N = 3), repeatability and reproducibility were 1.03-1.50 ng mL(-1), 3.9-5.1% and 7.3-8.2%, respectively. The total analysis time was 10.0 min.

  1. A mass spectrometric method for quantifying C3 and C6 phosphorylation of starch.

    PubMed

    Carpenter, Margaret; Joyce, Nigel; Butler, Ruth; Genet, Russell; Timmerman-Vaughan, Gail

    2012-12-15

    The glucosyl residues comprising starch can be phosphorylated at either the C3 or the C6 position of the molecule because of the activities of two distinct dikinase enzymes. After hydrolysis of the starch, the C6 phosphorylation is easy to measure using a routine enzyme assay for glucose 6-phosphate, but the C3 phosphorylation is more difficult to assay. A mass spectrometric (MS) method has been developed that, in a single run, can distinguish and quantify the glucose 3-phosphate and glucose 6-phosphate produced by hydrolysis of starch and can also measure the glucose content to give an accurate estimate of the starting material. The MS method involves quantification by LC/MS with external standards, using normal-phase hydrophilic interaction liquid chromatography and selective reaction monitoring. The MS method has been used to determine degrees of starch phosphorylation in a diverse group of potato lines, revealing threefold differences in phosphorylation between high- and low-phosphate lines. The method was also used to show that cold storage of potato tubers for up to 24weeks had little substantive effect on the levels of starch phosphorylation. MS provided an effective and efficient means of determining both the C6 and the C3 phosphorylation of starch.

  2. Determination of ractopamine in pig hair using liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Wu, Junlin; Liu, Xiaoyun; Peng, Yunping

    2014-01-01

    A quantitative analytical procedure for the determination of ractopamine in pig hair has been developed and validated. The hair samples were washed and incubated at 75°C with isoxuprine and hair extraction buffer. The drug present was quantified using mixed solid-phase extraction and liquid chromatography with tandem mass spectrometric detection. The limit of quantization (LOQ) was 10pg/mg and the intra-day precision at 25pg/mg and 750pg/mg was 0.49% and 2.8% respectively. Inter-day precision was 0.88% and 3.52% at the same concentrations. The hair extraction percentage recovery at 25pg/mg and 50ng/mL was 99.47% and 103.83% respectively. The extraction percentage recovery at 25pg/mg and 50ng/mg was 93.52% and 100.26% respectively. Our results showed that ractopamine residues persist in hair in 24days of withdrawal and also showed the possibility to test ractopamine from pig hair samples.

  3. Precise timing of the last interglacial period from mass spectrometric determination of thorium-230 in corals

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Wasserburg, G. J.; Ku, T.-L.; Edwards, R. Lawrence

    1987-01-01

    The development of mass spectrometric techniques for determination of Th-230 abundance has made it possible to reduce analytical errors in (U-238)-(U-234)-(Th-230) dating of corals even with very small samples. Samples of 6 x 10 to the 8th atoms of Th-230 can be measured to an accuracy of + or - 3 percent (2sigma), and 3 x 10 to the 10th atoms of Th-230 can be measured to an accuracy of + or - 0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to C-14 dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly post-date, the summer solar insolation high at 65 deg N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.

  4. Electrochemically-Modulated Separation and Mass Spectrometric Analysis of Actinides in Difficult Matrices

    SciTech Connect

    Duckworth, Douglas C.; Liezers, Martin; Lehn, Scott A.; Douglas, Matthew

    2009-01-01

    Electrochemically-modulated separations (EMS) are a straightforward means of isolating and pre-concentrating elements for on-line mass spectrometric analysis. Elements are accumulated at electrochemical working electrodes and subsequently released into a clean carrier solution for spectroscopic analysis. EMS can employ solely aqueous chemistry and uses electrochemical redox adjustment of oxidation state to “trigger” reversible chelation / complexation. Less tractable elements (e.g., uranium and plutonium), based on redox potentials, can therefore be extracted from difficult matrices following redox adjustment and chelation with electrode chelation sites. Simply put, separation is achieved by a small voltage step that is applied to the target electrode to turn “on” or “off” the specific actinide affinity of an electrode. This separation technology employs both redox and chelation chemistry to effect highly selective accumulation of target actinides, and results in element separation, matrix elimination and analyte preconcentration. Prior studies have developed protocols and preliminary insight into EMS processes for U and Pu. U and Pu are released upon oxidation and reduction, respectively, allowing complete separation due to widely divergent redox potentials. T The coupling of EMS on-line with ICP-MS for elemental and isotopic analysis of uranium and plutonium is presented, with a focus on analytical performance metrics and applicability to safeguards and process monitoring via nondestructive analyses.

  5. FT-ICR mass spectrometric and density functional theory studies of sulfate prenucleation clusters

    NASA Astrophysics Data System (ADS)

    Lemke, K. H.

    2012-12-01

    Recent mass spectrometric1 and relaxation spectroscopic studies2 of metal sulfate salts have demonstrated that aqueous clusters play an important role in sulfate prenucleation processes. While such studies provide evidence that that ion clusters are nucleation relevant species, ultra-high resolution mass spectrumetry, in particular, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/MS) can provide additional valuable information about the molecular composition and stability of individual ion clusters. Prompted by the above studies, our group has begun a systematic survey of metal sulfate clusters using FT-ICR mass spectrometry. Here, I report stoichiometries, structures and thermodynamic properties of calcium sulfate ion clusters, both "dry" and microsolvated, using electrospray ionization FT-ICR mass spectrometry in combination with semi-empirical methods and M062X/aug-cc-PVXZ level density functional theory calculations. In electrosprayed dilute aqueous solutions of CaSO4 (1-20mM), droplet desolvation results in the formation of stable doubly-charged clusters of [Ca(CaSO4)m(H2O)n]+2 (m≤10 & n≤9) as well as larger quadruply-charged ion clusters [Ca2(CaSO4)m(H2O)n]+4 with m≤23 and n≤10, demonstrating considerable sulfate nucleation potential in undersaturated electrolyte solutions. An attempt was also made to assess the extent of ion cluster aggregation in solution prior to electrospray ionization by measuring ion mass spectra at different solution concentrations. In brief, an increase in calcium sulfate concentration from 1-10mM results in a continuous increase in polynuclear ion cluster species, while smaller clusters, for instance, Ca[CaSO4]+2 and corresponding hydrated forms, become increasingly less abundant. Building on semi-empirical methods, M062X calculations have been applied to predict calcium sulfate cluster geometries, both "dry" and microsolvated, as well as the size-dependent evolution of clustering and hydration energies. 1

  6. Mass Spectrometric Detection of Neuropeptides Using Affinity-Enhanced Microdialysis with Antibody-Coated Magnetic Nanoparticles

    PubMed Central

    Schmerberg, Claire M.; Li, Lingjun

    2012-01-01

    Microdialysis (MD) is a useful sampling tool for many applications due to its ability to permit sampling from an animal concurrent with normal activity. MD is of particular importance in the field of neuroscience, in which it is used to sample neurotransmitters (NTs) while the animal is behaving in order to correlate dynamic changes in NTs with behavior. One important class of signaling molecules, the neuropeptides (NPs), however, presented significant challenges when studied with MD, due to the low relative recovery (RR) of NPs by this technique. Affinity-enhanced microdialysis (AE-MD) has previously been used to improve recovery of NPs and similar molecules. For AE-MD, an affinity agent (AA), such as an antibody-coated particle or free antibody, is added to the liquid perfusing the MD probe. This AA provides an additional mass transport driving force for analyte to pass through the dialysis membrane, and thus increases the RR. In this work, a variety of AAs have been investigated for AE-MD of NPs in vitro and in vivo, including particles with C18 surface functionality and antibody-coated particles. Antibody-coated magnetic nanoparticles (AbMnP) provided the best RR enhancement in vitro, with statistically significant (p<0.05) enhancements for 4 out of 6 NP standards tested, and RR increases up to 41-fold. These particles were then used for in vivo MD in the Jonah crab, Cancer borealis, during a feeding study, with mass spectrometric (MS) detection. 31 NPs were detected in a 30 min collection sample, compared to 17 when no AA was used. The use of AbMnP also increased the temporal resolution from 4–18 hrs in previous studies to just 30 min in this study. The levels of NPs detected were also sufficient for reliable quantitation with the MS system in use, permitting quantitative analysis of the concentration changes for 7 identified NPs on a 30 min time course during feeding. PMID:23249250

  7. Mass spectrometric detection of CYP450 adducts following oxidative desulfuration of methyl parathion.

    PubMed

    Kyle, Patrick B; Smith, Stanley V; Baker, Rodney C; Kramer, Robert E

    2013-07-01

    Cytochrome P450 (CYP)-mediated desulfuration of methyl parathion results in mechanism-based inhibition of the enzyme. Although previous data suggest that reactive sulfur is released and binds to the apoprotein, the identities of neither the adduct(s) nor the affected amino acid(s) have been clearly determined. In this study, nanospray tandem mass spectroscopy was used to analyze peptide digests of CYP resolved by SDS-PAGE from liver microsomes of male rats following incubation in the absence or presence of methyl parathion. Oxidative desulfuration was confirmed by measurement of methyl paraoxon, and inhibition of specific CYP isozymes was determined by measurement of testosterone hydroxylation. Total CYP content was quantified spectrophotometrically. Incubation of microsomes with methyl parathion decreased CYP content by 58%. This effect was not associated with a comparable increase in absorbance at 420 nm, suggesting the displacement of heme from the apoprotein. Rates of testosterone 2β- and 6β-hydroxylation, respectively, were reduced to 8 and 2%, implicating CYP3A and CYP2C11 in the oxidative desulfuration of methyl parathion. Mass spectrometric analysis identified 96 amu adducts to cysteines 64 and 378 of CYP3A1. In addition, a peptide containing cysteine 433 that coordinates with heme was possibly modified as it was detected in control, but not methyl parathion samples. A comparison of rat CYP3A1 with human CYP3A4 suggests that cysteines 64 and 378 reside along the substrate channel, remote from the active site. Alteration of these residues might modulate substrate entry to the binding pocket of the enzyme.

  8. Capillary liquid chromatography using laser-based and mass spectrometric detection. [Capillary zone electrophoresis (CZE); micellar electrokinetic capillary kchromatography (MECC)

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-01-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  9. Characterization of urban aerosol using aerosol mass spectrometry and proton nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cleveland, M. J.; Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Lefer, B.; Rappenglück, B.

    2012-07-01

    Particulate matter was measured during August and September of 2006 in Houston as part of the Texas Air Quality Study II Radical and Aerosol Measurement Project. Aerosol size and composition were determined using an Aerodyne quadrupole aerosol mass spectrometer. Aerosol was dominated by sulfate (4.1 ± 2.6 μg m-3) and organic material (5.5 ± 4.0 μg m-3), with contributions of organic material from both primary (˜32%) and secondary (˜68%) sources. Secondary organic aerosol appears to be formed locally. In addition, 29 aerosol filter samples were analyzed using proton nuclear magnetic resonance (1H NMR) spectroscopy to determine relative concentrations of organic functional groups. Houston aerosols are less oxidized than those observed elsewhere, with smaller relative contributions of carbon-oxygen double bonds. These particles do not fit 1H NMR source apportionment fingerprints for identification of secondary, marine, and biomass burning organic aerosol, suggesting that a new fingerprint for highly urbanized and industrially influenced locations be established.

  10. 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.

  11. 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.

  12. Ambient aerosol analysis using aerosol-time-of-flight mass spectrometry

    SciTech Connect

    Prather, K.A.; Noble, C.A.; Liu, D.Y.; Silva, P.J.; Fergenson, D.F.

    1996-10-01

    We have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the aerodynamic size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight mass spectrometry are combined in a single instrument. ATOFMS is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. Currently, measurements are being made to establish potential links between the presence of particular types of particles with such factors as the time of day, weather conditions, and concentration levels of gaseous smog components such as NO{sub x} and ozone. This data will be used to help establish a better understanding of tropospheric gas-aerosol processes. This talk will discuss the operating principles of ATOFMS as well as present the results of ambient analysis studies performed in our laboratory.

  13. Partial least-squares-discriminant analysis differentiating Chinese wolfberries by UPLC-MS and flow injection mass spectrometric (FIMS) fingerprints.

    PubMed

    Lu, Weiying; Jiang, Qianqian; Shi, Haiming; Niu, Yuge; Gao, Boyan; Yu, Liangli Lucy

    2014-09-17

    Lycium barbarum L. fruits (Chinese wolfberries) were differentiated for their cultivation locations and the cultivars by ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS) and flow injection mass spectrometric (FIMS) fingerprinting techniques combined with chemometrics analyses. The partial least-squares-discriminant analysis (PLS-DA) was applied to the data projection and supervised learning with validation. The samples formed clusters in the projected data. The prediction accuracies by PLS-DA with bootstrapped Latin partition validation were greater than 90% for all models. The chemical profiles of Chinese wolfberries were also obtained. The differentiation techniques might be utilized for Chinese wolfberry authentication.

  14. Solid-state UV-MALDI mass spectrometric quantitation of fluroxypyr and triclopyr in soil.

    PubMed

    Ivanova, Bojidarka; Spiteller, Michael

    2015-06-01

    The work presented here refers firstly to solid-state UV-MALDI-Orbitrap-mass spectrometric analysis of fluroxypyr (A) and triclopyr (B) in soils under laboratory conditions. The experimental design has involved the following: (a) determination of analytes A and B in polycrystalline composites of organic materials 1-7, based on 2-piperidine (pyrrolidine or piperazine)-1-yl-ethyl ammonium salts in order to determine the effect of sample preparation techniques on method performance using commercial herbicide formulations and (b) analysis of non-(X j,k,l (i) ) and sterilized (Y j,k,l (i) ) soil samples (i-fold rate 1, 10, 100, or 1,000; j-pesticide type A or B; k-time (0, 5, 10, 20, and 50 days) and l = 1-3 replicated samples) having clay content ∈ 5.0-12.0 %, silt ∈ 23.0-51.1 %, sand ∈ 7.2-72.0 %, and pH ∈ 4.0-8.1. In order to obtain a high representativeness of the data toward real-field experiments, the pollution scheme has involved 1-, 10-, 100-, and 1,000-fold rates. The firstfold rate has concentration of pollutant A of 2.639 × 10(-4) g in 625 cm(2) soil horizon of 0-25 cm(2) (5 cm depth) according to registration report (PSM-Zulassungbericht) of German Federal Office of Consumer Protection and Food Safety (Bundesamt für Verbraucherschutz und Lebensmittelsicherheit) 6337/26.10.2009. The experimental design has involved quincunx systematic statistical approach for collection of soil samples. The performance has been compared with the corresponding statistical variable obtained, using an independent HPLC-ESI-(APCI-)-MS/MS analysis.

  15. On-line monitoring of continuous beer fermentation process using automatic membrane inlet mass spectrometric system.

    PubMed

    Tarkiainen, Virpi; Kotiaho, Tapio; Mattila, Ismo; Virkajärvi, Ilkka; Aristidou, Aristos; Ketola, Raimo A

    2005-03-15

    A fully automatic membrane inlet mass spectrometric (MIMS) on-line instrumentation for the analysis of aroma compounds in continuous beer fermentation processes was constructed and tested. The instrumentation includes automatic filtration of the sample stream, flushing of all tubing between samples and pH control. The calibration standards can be measured periodically. The instrumentation has also an extra sample line that can be used for off-line sample collection or it can be connected to another on-line method. Detection limits for ethanol, acetic acid and eight organic beer aroma compounds were from mugl(-1) to low mgl(-1) levels and the standard deviations were less than 3.4%. The method has a good repeatability and linearity in the measurement range. Response times are shorter than or equal to 3min for all compounds except for ethyl caproate, which has a response time of 8min. In beer aroma compound analysis a good agreement between MIMS and static headspace gas chromatographic (HSGC) measurements was found. The effects of different matrix compounds commonly present in the fermentation media on the MIMS response to acetaldehyde, ethyl acetate and ethanol were studied. Addition of yeast did not have any effect on the MIMS response of ethanol or ethyl acetate. Sugars, glucose and xylose, increased the MIMS response of all studied analytes only slightly, whereas salts, ammonium chloride, ammonium nitrate and sodium chloride, increased the MIMS response of all three studied compounds prominently. The system was used for on-line monitoring of continuous beer fermentation with immobilised yeast. The results show that with MIMS it is possible to monitor the changes in the continuous process as well as delays in the two-phase process.

  16. Gas chromatographic and mass spectrometric investigations of organic residues from Roman glass unguentaria.

    PubMed

    Ribechini, Erika; Modugno, Francesca; Colombini, Maria Perla; Evershed, Richard P

    2008-03-07

    A combination of gas chromatographic (GC) and mass spectrometric (MS) techniques, including direct exposure-MS (DE-MS), high-temperature GC-MS (HTGC-MS) and GC-MS of neutral and acid fractions, was employed to study the composition and recognise origin of the organic materials used to manufacture balm residues surviving in a series of glass unguentaria recovered from excavations of a Roman villa (Villa B) in the ancient town of Oplontis (Naples, Italy). DE-MS provided comprehensive 'fingerprint' information on the solvent soluble components of the contents of the unguentaria, while GC-MS analyses provided detailed molecular compositions, highlighting the presence of a wide range of compound classes including mid- and long-chain fatty acids, long-chain hydroxy-acids, n-alkanols, alkandiols, n-alkanes, long-chain monoesters, phytosterols and diterpenoid acids. Characteristic biomarkers and their distributions indicate the presence of beeswax, Pinaceae resin and another wax, as the main organic constituents of all of the preparations examined. In particular, the occurrence of phytosterols and long-chain monoesters, in which the acyl moiety was not exclusively palmitic acid, suggested the presence of a second waxy-lipid constituent of plant origin. The results are consistent with beeswax being used in the preparation of the cosmetics preserved in the unguentaria, while the other lipids are most likely the residue of some as yet unidentified plant extract(s), possibly deriving from the cuticular waxes of flowers and/or leaves. The composition of the extracts are consistent with the ancient practices of maceration and/or "enfleurage", in which lipid-based materials, such as beeswax, animal fat or vegetables oils, were used to extract aromatic and fragrant substances from resin, flowers, spices and scented wood, in order to produce unguents and balms.

  17. Correlation of aerosol mass near the ground with aerosol optical depth during two seasons in Munich

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Harbusch, Andreas; Emeis, Stefan; Koepke, Peter; Wiegner, Matthias

    2008-06-01

    Relations of the aerosol optical depth (AOD) with aerosol mass concentration near the ground, particulate matter (PM), have been studied on the basis of measurements. The objective is with respect to possible remote sensing methods to get information on the spatial and temporal variation of aerosols which is important for human health effects. Worldwide the AOD of the atmospheric column is routinely monitored by sun-photometers and accessible from satellite measurements also. It is implied here that the AOD is caused mainly by attenuation processes within the mixing layer because this layer includes nearly all atmospheric aerosols. Thus the mixing layer height (MLH) is required together with the AOD, measured by ground-based sun-photometers (around 560 nm), to get information about aerosols near the ground. MLH is determined here from surface-based remote sensing. Investigations were performed during two measurement campaigns in and near Munich in May and November/December 2003 on the basis of daily mean values. Using AOD and MLH measurements the aerosol extinction coefficient of the mixing layer has been calculated. This quantity was correlated with the measured PM10, PM2.5 and PM1 mass concentrations near the ground by performing a linear regression and thus providing a mass extinction efficiency giving squares of the correlation coefficients (R2) between 0.48 (PM1 during summer campaign) and 0.90 (PM2.5 during winter campaign). These correlations suggest that the derived mass extinction efficiencies represent a statistically significant relation between the aerosol extinction coefficients and the surface-based PM mass concentrations mainly during winter conditions.

  18. Lipopeptides from the Banyan Endophyte, Bacillus subtilis K1: Mass Spectrometric Characterization of a Library of Fengycins

    NASA Astrophysics Data System (ADS)

    Pathak, Khyati V.; Keharia, Haresh; Gupta, Kallol; Thakur, Suman S.; Balaram, Padmanabhan

    2012-10-01

    Mass spectrometric analysis of a banyan endophyte, Bacillus subtilis K1, extract showing broad spectrum antifungal activity revealed a complex mixture of lipopeptides, iturins, surfactins, and fengycins. Fractionation by reversed-phase high performance liquid chromatography (HPLC) facilitated a detailed analysis of fengycin microheterogeneity. Matrix assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometric studies permitted the identification of several new fengycin variants. Four major sites of heterogeneity are identified: (1) N-terminus β-hydroxy fatty acid moiety, where chain length variation and the presence of unsaturation occur, (2) position 6 (Ala/Val/Ile/Leu), (3) position 10 (Val/Ile) within the macrocyclic ring, and (4) Gln to Glu replacement at position 8, resulting in fengycin variants that differ in mass by 1 Da. Diagnostic fragment ions provide a quick method for localizing the sites of variation in the macrocycle or the linear segment. Subsequent establishment of the sequences is achieved by MS/MS analysis of linear fengycin species produced by hydrolysis of the macrocyclic lactone. Unsaturation in the fatty acid chain and the presence of linear precursors in the B. subtilis K1 extract are also established by mass spectrometry. The anomalous distribution of intensities within isotopic multiplets is a diagnostic for Gln/Glu replacements. High resolution mass spectrometry facilitates the identification of fengycin species differing by 1 Da by localizing the variable position (Gln8/Glu8) in the fengycin variants.

  19. Development of a continuous aerosol mass concentration measurement device.

    PubMed

    Bémer, D; Thomas, D; Contal, P; Subra, I

    2003-08-01

    A dynamic aerosol mass concentration measurement device has been developed for personal sampling. Its principle consists in sampling the aerosol on a filter and monitoring the change of pressure drop over time (Delta P). Ensuring that the linearity of the Delta P = f(mass of particles per unit area of filter) relationship has been well established, the change of concentration can be deduced. The response of the system was validated in the laboratory with a 3.5 microm alumina aerosol (mass median diameter) generated inside a 1-m(3) ventilated enclosure. As the theory predicted that the mass sensitivity of the system would vary inversely with the square of the particle diameter, only sufficiently fine aerosols were able to be measured. The system was tested in the field in a mechanical workshop in the vicinity of an arc-welding station. The aerosol produced by welding is indeed particularly well-adapted due to the sub-micronic size of the particles. The device developed, despite this limitation, has numerous advantages over other techniques: robustness, compactness, reliability of calibration, and ease of use.

  20. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  1. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    SciTech Connect

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-03-02

    We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10-5 to 10-11. Free molecular heat and mass transfer

  2. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-05-01

    An electrostatic size classification technique was used to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Size-segregated particles were counted with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10- 5 to 10- 11. Free molecular heat and mass transfer theory was applied, but

  3. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    DOE PAGES

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-03-02

    We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized bymore » the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10-5 to 10-11. Free molecular heat and mass transfer theory was

  4. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien Khoi V.; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-01

    Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements.

  5. Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols.

    PubMed

    Kourtchev, Ivan; Giorio, Chiara; Manninen, Antti; Wilson, Eoin; Mahon, Brendan; Aalto, Juho; Kajos, Maija; Venables, Dean; Ruuskanen, Taina; Levula, Janne; Loponen, Matti; Connors, Sarah; Harris, Neil; Zhao, Defeng; Kiendler-Scharr, Astrid; Mentel, Thomas; Rudich, Yinon; Hallquist, Mattias; Doussin, Jean-Francois; Maenhaut, Willy; Bäck, Jaana; Petäjä, Tuukka; Wenger, John; Kulmala, Markku; Kalberer, Markus

    2016-10-13

    Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples. Here we resolve this long-standing discrepancy by showing that elevated SOA mass is one of the key drivers of oligomer formation in the ambient atmosphere and laboratory experiments. We show for the first time that a specific organic compound class in aerosols, oligomers, is strongly correlated with cloud condensation nuclei (CCN) activities of SOA particles. These findings might have important implications for future climate scenarios where increased temperatures cause higher biogenic volatile organic compound (VOC) emissions, which in turn lead to higher SOA mass formation and significant changes in SOA composition. Such processes would need to be considered in climate models for a realistic representation of future aerosol-climate-biosphere feedbacks.

  6. Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan; Giorio, Chiara; Manninen, Antti; Wilson, Eoin; Mahon, Brendan; Aalto, Juho; Kajos, Maija; Venables, Dean; Ruuskanen, Taina; Levula, Janne; Loponen, Matti; Connors, Sarah; Harris, Neil; Zhao, Defeng; Kiendler-Scharr, Astrid; Mentel, Thomas; Rudich, Yinon; Hallquist, Mattias; Doussin, Jean-Francois; Maenhaut, Willy; Bäck, Jaana; Petäjä, Tuukka; Wenger, John; Kulmala, Markku; Kalberer, Markus

    2016-10-01

    Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples. Here we resolve this long-standing discrepancy by showing that elevated SOA mass is one of the key drivers of oligomer formation in the ambient atmosphere and laboratory experiments. We show for the first time that a specific organic compound class in aerosols, oligomers, is strongly correlated with cloud condensation nuclei (CCN) activities of SOA particles. These findings might have important implications for future climate scenarios where increased temperatures cause higher biogenic volatile organic compound (VOC) emissions, which in turn lead to higher SOA mass formation and significant changes in SOA composition. Such processes would need to be considered in climate models for a realistic representation of future aerosol-climate-biosphere feedbacks.

  7. Enhanced Volatile Organic Compounds emissions and organic aerosol mass increase the oligomer content of atmospheric aerosols

    PubMed Central

    Kourtchev, Ivan; Giorio, Chiara; Manninen, Antti; Wilson, Eoin; Mahon, Brendan; Aalto, Juho; Kajos, Maija; Venables, Dean; Ruuskanen, Taina; Levula, Janne; Loponen, Matti; Connors, Sarah; Harris, Neil; Zhao, Defeng; Kiendler-Scharr, Astrid; Mentel, Thomas; Rudich, Yinon; Hallquist, Mattias; Doussin, Jean-Francois; Maenhaut, Willy; Bäck, Jaana; Petäjä, Tuukka; Wenger, John; Kulmala, Markku; Kalberer, Markus

    2016-01-01

    Secondary organic aerosol (SOA) accounts for a dominant fraction of the submicron atmospheric particle mass, but knowledge of the formation, composition and climate effects of SOA is incomplete and limits our understanding of overall aerosol effects in the atmosphere. Organic oligomers were discovered as dominant components in SOA over a decade ago in laboratory experiments and have since been proposed to play a dominant role in many aerosol processes. However, it remains unclear whether oligomers are relevant under ambient atmospheric conditions because they are often not clearly observed in field samples. Here we resolve this long-standing discrepancy by showing that elevated SOA mass is one of the key drivers of oligomer formation in the ambient atmosphere and laboratory experiments. We show for the first time that a specific organic compound class in aerosols, oligomers, is strongly correlated with cloud condensation nuclei (CCN) activities of SOA particles. These findings might have important implications for future climate scenarios where increased temperatures cause higher biogenic volatile organic compound (VOC) emissions, which in turn lead to higher SOA mass formation and significant changes in SOA composition. Such processes would need to be considered in climate models for a realistic representation of future aerosol-climate-biosphere feedbacks. PMID:27733773

  8. Background aerosol over the Himalayas and Tibetan Plateau: observed characteristics of aerosol mass loading

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Cong, Zhiyuan; Wang, Yuesi; Xin, Jinyuan; Wan, Xin; Pan, Yuepeng; Liu, Zirui; Wang, Yonghong; Zhang, Guoshuai; Wang, Zhongyan; Wang, Yongjie; Kang, Shichang

    2017-01-01

    To investigate the atmospheric aerosols of the Himalayas and Tibetan Plateau (HTP), an observation network was established within the region's various ecosystems, including at the Ngari, Qomolangma (QOMS), Nam Co, and Southeastern Tibetan (SET) stations. In this paper we illustrate aerosol mass loadings by integrating in situ measurements with satellite and ground-based remote sensing datasets for the 2011-2013 period, on both local and large scales. Mass concentrations of these surface atmospheric aerosols were relatively low and varied with land cover, showing a general tendency of Ngari and QOMS (barren sites) > Nam Co (grassland site) > SET (forest site). Daily averages of online PM2.5 (particulates with aerodynamic diameters below 2.5 µm) at these sites were sequentially 18.2 ± 8.9, 14.5 ± 7.4, 11.9 ± 4.9 and 11.7 ± 4.7 µg m-3. Correspondingly, the ratios of PM2.5 to total suspended particles (TSP) were 27.4 ± 6.65, 22.3 ± 10.9, 37.3 ± 11.1 and 54.4 ± 6.72 %. Bimodal mass distributions of size-segregated particles were found at all sites, with a relatively small peak in accumulation mode and a more notable peak in coarse mode. Diurnal variations in fine-aerosol masses generally displayed a bi-peak pattern at the QOMS, Nam Co and SET stations and a single-peak pattern at the Ngari station, controlled by the effects of local geomorphology, mountain-valley breeze circulation and aerosol emissions. Dust aerosol content in PM2.1 samples gave fractions of 26 % at the Ngari station and 29 % at the QOMS station, or ˜ 2-3 times that of reported results at human-influenced sites. Furthermore, observed evidence confirmed the existence of the aerodynamic conditions necessary for the uplift of fine particles from a barren land surface. Combining surface aerosol data and atmospheric-column aerosol optical properties, the TSP mass and aerosol optical depth (AOD) of the Multi-angle Imaging Spectroradiometer (MISR) generally decreased as land cover changed from

  9. Asymmetric Morita-Baylis-Hillman Reaction: Catalyst Development and Mechanistic Insights Based on Mass Spectrometric Back-Reaction Screening.

    PubMed

    Isenegger, Patrick G; Bächle, Florian; Pfaltz, Andreas

    2016-12-05

    An efficient protocol for the evaluation of catalysts for the asymmetric Morita-Baylis-Hillman (MBH) reaction was developed. By mass spectrometric back-reaction screening of quasi-enantiomeric MBH products, an efficient bifunctional phosphine catalyst was identified that outperforms literature-known catalysts in the MBH reaction of methyl acrylate with aldehydes. The close match between the selectivities measured for the forward and back reaction and kinetic measurements provided strong evidence that the aldol step and not the subsequent proton transfer is rate- and enantioselectivity-determining.

  10. Gas chromatographic/mass spectrometric analyses of unknown analytical response in imported Fava beans: 4-chloro-6-methoxyindole.

    PubMed

    Petzinger, G; Barry, T L; Roach, J A; Musser, S M; Sphon, J

    1995-01-01

    A halogenated unidentified analytical response (UAR) was encountered in a number of imported Fava bean samples during the Food and Drug Administration's routine pesticide-monitoring program. Gas chromatographic/mass spectrometric (GC/MS) analyses identified the halogenated component as 4-chloro-6-methoxyindole, a naturally occurring promutagen in Fava beans that has been linked to incidents of gastric cancer. Data from electron impact, positive and negative chemical ionization, collision-induced dissociation, and deuteration studies of this compound are presented, along with GC retention time data.

  11. Characterization of ambient aerosols at the San Francisco International Airport using BioAerosol Mass Spectrometry

    SciTech Connect

    Steele, P T; McJimpsey, E L; Coffee, K R; Fergenson, D P; Riot, V J; Tobias, H J; Woods, B W; Gard, E E; Frank, M

    2006-03-16

    The BioAerosol Mass Spectrometry (BAMS) system is a rapidly fieldable, fully autonomous instrument that can perform correlated measurements of multiple orthogonal properties of individual aerosol particles. The BAMS front end uses optical techniques to nondestructively measure a particle's aerodynamic diameter and fluorescence properties. Fluorescence can be excited at 266nm or 355nm and is detected in two broad wavelength bands. Individual particles with appropriate size and fluorescence properties can then be analyzed more thoroughly in a dual-polarity time-of-flight mass spectrometer. Over the course of two deployments to the San Francisco International Airport, more than 6.5 million individual aerosol particles were fully analyzed by the system. Analysis of the resulting data has provided a number of important insights relevant to rapid bioaerosol detection, which are described here.

  12. Design and performance of a mass spectrometric facility for measuring helium isotopes in natural waters and for low-level tritium determination by the 3He ingrowth method.

    PubMed

    Jean-Baptiste, P; Mantisi, F; Dapoigny, A; Stievenard, M

    1992-07-01

    The design and performance of a mass spectrometric system for the measurement of helium isotopes and very low tritium concentrations in natural waters are described and discussed in the light of analytical precision and accuracy. The system consists of a VG 3000 mass spectrometer with a fully automated inlet system for preparation and purification of the samples. Along with this mass spectrometric system, different custom-fabricated units are described, especially designed for taking samples, extracting helium or degassing tritium samples prior to the mass spectrometric analysis. The 3He detection limit of the system is close to 10(-16) cm3 STP corresponding to a tritium level of 0.003 TU for a 500 g water sample stored six months for 3He regrowth. A vertical oceanic tritium profile from the south hemisphere is presented as an illustration of the system's capability to detect very low tritium concentrations in the environment.

  13. THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514)

    EPA Science Inventory

    The mass transfer rate of pure ammonium nitrate between the aerosol and gas phases was
    quantified experimentally by the use of the tandem differential mobility analyzer/scanning mobility
    particle sizer (TDMA/SMPS) technique. Ammonium nitrate particles 80-220 nm in diameter<...

  14. Aerosol mass spectrometry systems and methods

    DOEpatents

    Fergenson, David P.; Gard, Eric E.

    2013-08-20

    A system according to one embodiment includes a particle accelerator that directs a succession of polydisperse aerosol particles along a predetermined particle path; multiple tracking lasers for generating beams of light across the particle path; an optical detector positioned adjacent the particle path for detecting impingement of the beams of light on individual particles; a desorption laser for generating a beam of desorbing light across the particle path about coaxial with a beam of light produced by one of the tracking lasers; and a controller, responsive to detection of a signal produced by the optical detector, that controls the desorption laser to generate the beam of desorbing light. Additional systems and methods are also disclosed.

  15. Determination of beta-2 microglobulin levels in plasma using a high-throughput mass spectrometric immunoassay system.

    PubMed

    Niederkofler, E E; Tubbs, K A; Gruber, K; Nedelkov, D; Kiernan, U A; Williams, P; Nelson, R W

    2001-07-15

    A high-throughput mass spectrometric immunoassay (MSIA) system for the analysis of proteins directly from biological fluids is reported. A 96-well-format robotic workstation equipped with antibody-derivatized affinity pipet tips was used for the parallel extraction of specific proteins from samples and subsequent deposition onto 96-well arrayed matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) targets. Interferences from nonspecifically bound proteins were minimized through choice of appropriate affinity pipet tip derivatization chemistries. Sample preparation for MALDI-TOFMS was enhanced through the use of hydrophobic/hydrophilic contrasting targets, which also presented functionalities found to promote matrix/analyte crystal growth. Automated mass spectrometry was used in the unattended acquisition of data, resulting in an analysis rate of approximately 100 samples/h (biological fluid-->data). The quantitative MSIA of beta2m levels present in human plasma samples is given as illustration.

  16. Comprehensive Characterization of Atmospheric Organic Carbon using Multiple High-Resolution Mass Spectrometric Instruments

    NASA Astrophysics Data System (ADS)

    Kroll, J. H.; Hunter, J. F.; Isaacman-VanWertz, G. A.

    2015-12-01

    Accurate modeling of major atmospheric chemical processes (oxidant cycling, aerosol formation, etc.) requires understanding the identity, chemistry, and lifecycle (emission, reaction, and deposition) of atmospheric organic species. Such an understanding is generally limited by the wide diversity in chemical structure, properties, and reactivity of atmospheric organics, posing major challenges in detection and quantification. However the last several years have seen the development of several new techniques for the measurement of a wide range of carbon-containing compounds, including low-volatility, oxidized species that have traditionally been difficult to measure. Many of these new techniques are based on high-resolution mass spectrometry, enabling the unambiguous identification of individual ions, and hence the elemental ratios and carbon oxidation state of the organic species; most also provide information on volatility and/or carbon number distributions of the molecular species. While a single instrument can generally measure only species of a particular class (occupying a localized region of "chemical space"), here we show that the combined measurements from multiple instruments can provide a comprehensive picture of the chemical composition of the entire organic mixture. From these combined measurements, the organic species can be described not only in terms of organic carbon mass but also in terms of distributions of key ensemble properties (such as oxidation state and volatility), and thus can be used to populate and constrain the various reduced-dimensionality chemical spaces that have been put forth as frameworks for describing atmospheric organic chemistry. We apply this general measurement approach both to field data, providing information on ambient organic species, and to laboratory (chamber) studies, providing insight into the chemical transformations that organic species undergo upon atmospheric oxidation.

  17. Evaluation of affinity-based serum clean-up in mass spectrometric analysis: Plastic vs monoclonal antibodies.

    PubMed

    Rossetti, Cecilia; Levernæs, Maren C S; Reubsaet, Léon; Halvorsen, Trine G

    2016-11-04

    Mass spectrometric assays are now of great relevance for trace compound analysis in complex matrices such as serum and plasma samples. Especially in the quantification of low abundant protein-biomarkers, the choice of the sample preparation is crucial. In the present paper immunocapture and Molecular Imprinted Polymers (MIPs) have been applied in the determination of pro-gastrin-releasing peptide, a Small Cell Lung Cancer marker. These affinity-based techniques were compared in terms of matrix effect, limits of detection, repeatability and extraction specificity. In addition, protein precipitation was included for comparison as it is a typical sample preparation method of biological matrices. The results highlighted differences in the methods' performance and specificity, strongly affecting the outcome of the mass spectrometric determination. Plastic and monoclonal antibodies confirmed to be sensitive and specific sample preparations able to determine ProGRP at clinical relevant concentration, although only the use of monoclonal antibodies allowed the reliable quantification of ProGRP at reference levels (8pM). In addition better insight in the specificity of the three sample preparation techniques was gained. This might also be of interest for other biological applications.

  18. Mass spectroscopy of single aerosols from field measurements

    SciTech Connect

    Thomson, D.S.; Murphy, D.M.

    1995-12-31

    We are developing an aircraft instrument for the chemical analysis of individual ambient aerosols in real time. In order to test the laboratory version of this instrument, we participated in a field campaign near the continental divide in Colorado in September, 1993. During this campaign, over 5000 mass spectra of ambient aerosols were collected. Analysis of the negative ion spectra shows that sulfate was the most commonly seen component of smaller particles, while nitrate was more common in larger particles. Organic compounds are present in most particles, and we believe we can distinguish inorganic carbon in some particles. Although numerous distinct classes of particles were observed, indicating external mixtures, almost all of these particle types were themselves mixtures of several compounds. Finally, we note that although the field site experienced distinct polluted and unpolluted episodes, aerosol composition did not correlate with gas phase chemistry.

  19. The Mechanism of 2-Furaldehyde Formation from d-Xylose Dehydration in the Gas Phase. A Tandem Mass Spectrometric Study

    NASA Astrophysics Data System (ADS)

    Ricci, Andreina; Piccolella, Simona; Pepi, Federico; Garzoli, Stefania; Giacomello, Pierluigi

    2013-07-01

    The mechanism of reactions occurring in solution can be investigated also in the gas phase by suited mass spectrometric techniques, which allow to highlight fundamental mechanistic features independent of the influence of the medium and to clarifying controversial hypotheses proposed in solution studies. In this work, we report a gas-phase study performed by electrospray triple stage quadrupole mass spectrometry (ESI-TSQ/MS) on the dehydration of d-xylose, leading mainly to the formation of 2-furaldehyde (2-FA). It is generally known in carbohydrate chemistry that the thermal acid catalyzed dehydration of pentoses leads to the formation of 2-FA, but several aspects on the solution-phase mechanism are controversial. Here, gaseous reactant ions corresponding to protonated xylose molecules obtained from ESI of a solution containing d-xylose and ammonium acetate as protonating reagent were allowed to undergo collisionally activated decomposition (CAD) into the triple stage quadrupole analyzer. The product ion mass spectra of protonated xylose are characterized by the presence of ionic intermediates arising from xylose dehydration, which were structurally characterized by their fragmentation patterns. As expected, the xylose triple dehydration leads to the formation of the ion at m/z 97, corresponding to protonated 2-FA. On the basis of mass spectrometric evidences, we demonstrated that in the gas phase, the formation of 2-FA involves protonation at the OH group bound to the C1 atom of the sugar, the first ionic intermediate being characterized by a cyclic structure. Finally, energy resolved product ion mass spectra allowed to obtain information on the energetic features of the d-xylose→2-FA conversion.

  20. Derivation of Aerosol Columnar Mass from MODIS Optical Depth

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; Hegg, Dean A.

    2003-01-01

    In order to verify performance, aerosol transport models (ATM) compare aerosol columnar mass (ACM) with those derived from satellite measurements. The comparison is inherently indirect since satellites derive optical depths and they use a proportionality constant to derive the ACM. Analogously, ATMs output a four dimensional ACM distribution and the optical depth is linearly derived. In both cases, the proportionality constant requires a direct intervention of the user by prescribing the aerosol composition and size distribution. This study introduces a method that minimizes the direct user intervention by making use of the new aerosol products of MODIS. A parameterization is introduced for the derivation of columnar aerosol mass (AMC) and CCN concentration (CCNC) and comparisons between sunphotometer, MODIS Airborne Simulator (MAS) and in-measurements are shown. The method still relies on the scaling between AMC and optical depth but the proportionality constant is dependent on the MODIS derived r$_{eff}$,\\eta (contribution of the accumulation mode radiance to the total radiance), ambient RH and an assumed constant aerosol composition. The CCNC is derived fkom a recent parameterization of CCNC as a function of the retrieved aerosol volume. By comparing with in-situ data (ACE-2 and TARFOX campaigns), it is shown that retrievals in dry ambient conditions (dust) are improved when using a proportionality constant dependent on r$ {eff}$ and \\eta derived in the same pixel. In high humidity environments, the improvement inthe new method is inconclusive because of the difficulty in accounting for the uneven vertical distribution of relative humidity. Additionally, two detailed comparisons of AMC and CCNC retrieved by the MAS algorithm and the new method are shown. The new method and MAS retrievals of AMC are within the same order of magnitude with respect to the in-situ measurements of aerosol mass. However, the proposed method is closer to the in-situ measurements than

  1. Reactions and mass spectra of complex particles using Aerosol CIMS

    NASA Astrophysics Data System (ADS)

    Hearn, John D.; Smith, Geoffrey D.

    2006-12-01

    Aerosol chemical ionization mass spectrometry (CIMS) is used both on- and off-line for the analysis of complex laboratory-generated and ambient particles. One of the primary advantages of Aerosol CIMS is the low degree of ion fragmentation, making this technique well suited for investigating the reactivity of complex particles. To demonstrate the usefulness of this "soft" ionization, particles generated from meat cooking were reacted with ozone and the composition was monitored as a function of reaction time. Two distinct kinetic regimes were observed with most of the oleic acid in these particles reacting quickly but with 30% appearing to be trapped in the complex mixture. Additionally, detection limits are measured to be sufficiently low (100-200 ng/m3) to detect some of the more abundant constituents in ambient particles, including sulfate, which is measured in real-time at 1.2 [mu]g/m3. To better characterize complex aerosols from a variety of sources, a novel off-line collection method was also developed in which non-volatile and semi-volatile organics are desorbed from particles and concentrated in a cold U-tube. Desorption from the U-tube followed by analysis with Aerosol CIMS revealed significant amounts of nicotine in cigarette smoke and levoglucosan in oak and pine smoke, suggesting that this may be a useful technique for monitoring particle tracer species. Additionally, secondary organic aerosol formed from the reaction of ozone with R-limonene and volatile organics from orange peel were analyzed off-line showing large molecular weight products (m/z > 300 amu) that may indicate the formation of oligomers. Finally, mass spectra of ambient aerosol collected offline reveal a complex mixture of what appears to be highly processed organics, some of which may contain nitrogen.

  2. In situ probing of cholesterol in astrocytes at the single-cell level using laser desorption ionization mass spectrometric imaging with colloidal silver.

    PubMed

    Perdian, D C; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S; Yeung, Edward S; Lee, Young Jin

    2010-04-30

    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.

  3. 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.

  4. Organic Aerosols in Rural and Remote Atmospheric Environments: Insights from Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Jimenez, J.; Ulbrich, I.; Dunlea, E.; Decarlo, P.; Huffman, A.; Allan, J.; Coe, H.; Alfarra, R.; Canagaratna, M.; Onasch, T.; Jayne, J.; Worsnop, D.; Takami, A.; Miyoshi, T.; Shimono, A.; Hatakeyama, S.; Weimer, S.; Demerjian, K.; Drewnick, F.; Schneider, J.; Middlebrook, A.; Bahreini, R.; Cotrell, L.; Griffin, R.; Leaitch, R.; Li, S.; Hayden, K.; Rautiainen, J.

    2006-12-01

    Organic matter usually accounts for a large fraction of the fine particle mass in rural and remote atmospheres. However, little is known about the sources and properties of this material. Here we report findings on the characteristics and the major types of organic aerosols (OA) in urban downwind, high elevation, forested, and marine atmospheres based on analyses of more than 20 highly time resolved AMS datasets sampled from various locations in the mid-latitude Northern Hemisphere. Organic aerosol components are extracted from these datasets using a custom multiple component mass spectral analysis technique and the Positive Matrix Factorization (PMF) method. These components are evaluated according to their extracted mass spectra and correlations to aerosol species, such as sulfate, nitrate, and elemental carbon, and gas-phase tracer compounds, such as CO and NOx. We have identified a hydrocarbon-like organic aerosol (HOA) component similar in mass spectra to the hydrocarbon substances observed at urban locations. We have also identified several oxygenated OA (OOA) components that show different fragmentation patterns and oxygen to carbon ratios in their mass spectra. Two OOA components a highly oxygenated that has mass spectrum resembling that of fulvic acid (a model compound representative for highly processed/oxidized organics in the environment) and a less oxygenated OOA component, whose spectrum is dominated with ions that are mainly associated with carbonyls and alcohols, are very frequently observed at various rural/remote sites. The oxygenated OOA component is more prevalent at downwind sites influenced by urban transport and the less oxygenated shows correlation to biogenic chamber OA at some locations. Compared to the total OOA concentration, HOA is generally very small and accounts for < 10% of the total OA mass at rural/remote sites. The comparisons between the concentrations of HOA and primary OA (POA) that would be predicted according to inert

  5. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    PubMed

    Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

    2011-01-01

    In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station.

  6. Pyridine N-oxide and pyridine-d5 N-oxide: an electrospray/tandem mass spectrometric study carried out at high mass resolution.

    PubMed

    March, Raymond E; Stadey, Christopher J; Lewars, Errol G

    2005-01-01

    A mass spectrometric study of pyridine N-oxide and pyridine-d5 N-oxide was carried out with a hybrid quadrupole/time-of-flight (TOF) mass spectrometer coupled with an electrospray (ES) source. In addition to the observation of protonated, sodiated, and proton-bound dimers of pyridine N-oxide and pyridine-d5 N-oxide, mass scans revealed the presence of several doubly-charged ion species. Doubly-charged ions of m/z 191 were identified as diprotonated tetramers of pyridine N-oxide; a structure has been proposed for the diprotonated tetramer and its energy relative to that of protonated pyridine N-oxide has been obtained from geometry optimizations. The principal ion species observed were subjected to collision-induced dissociation; accurate mass measurements were made of each fragment ion so as to determine its elemental composition. On the basis of mass spectrometric evidence, it is suggested that dissociation of pyridine N-oxide may occur during the ES process and the resulting fragments become embedded in doubly-charged ions. The proton affinity for both pyridine N-oxide and pyridine-d5 N-oxide was calculated; the difference between these proton affinities was compared with an experimentally determined difference between the proton affinities of pyridine N-oxide and pyridine-d5 N-oxide.

  7. Immunopurification and mass spectrometric quantification of the active form of a chimeric therapeutic antibody in human serum.

    PubMed

    Dubois, Mathieu; Fenaille, François; Clement, Gilles; Lechmann, Martin; Tabet, Jean-Claude; Ezan, Eric; Becher, François

    2008-03-01

    In this study, we show that liquid chromatography coupled with tandem mass spectrometry provides a sensitive, specific, and accurate absolute quantification of Erbitux, a human:murine chimeric mAb used for the treatment of colorectal cancer. Micrometric magnetized beads, functionalized with soluble epidermal growth factor receptor (sEGFR), the pharmacological target of Erbitux, were used for specific immunocapture of Erbitux allowing assessment of the antibody's biological potency and sample purification. Following digestion with trypsin, specific peptides from light and heavy chains were monitored in the selected reaction monitoring (SRM) mode. Assay variability below 20% was provided through optimization of the digestion step and rigorous monitoring of the whole analytical process using an appropriate internal standard. The 20 ng/mL lower limit of quantification was similar to that of ELISA methods. These results show that this mass spectrometric approach is a potential alternative for pharmacokinetic evaluation of mAbs during clinical development.

  8. Direct tandem mass spectrometric analysis of amino acids in plasma using fluorous derivatization and monolithic solid-phase purification.

    PubMed

    Tamashima, Erina; Hayama, Tadashi; Yoshida, Hideyuki; Imakyure, Osamu; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2015-11-10

    In this study, we developed a novel direct tandem mass spectrometric method for rapid and accurate analysis of amino acids utilizing a fluorous derivatization and purification technique. Amino acids were perfluoroalkylated with 2H,2H,3H,3H-perfluoroundecan-1-al in the presence of 2-picoline borane via reductive amination. The derivatives were purified by perfluoroalkyl-modified silica-based monolithic solid-phase extraction (monolithic F-SPE), and directly analyzed by tandem mass spectrometry using electrospray ionization without liquid chromatographic separation. The perfluoroalkyl derivatives could be sufficiently distinguished from non-fluorous compounds, i.e. the biological matrix, due to their fluorous interaction. Thus, rapid and accurate determination of amino acids was accomplished. The method was validated with human plasma samples and applied to the analysis of amino acids in the plasma of mice with maple syrup urine disease or phenylketonuria.

  9. 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.

  10. Ultraviolet irradiation-induced substitution of fluorine with hydroxyl radical for mass spectrometric analysis of perfluorooctane sulfonyl fluoride.

    PubMed

    Wang, Peng; Tang, Xuemei; Huang, Lulu; Kang, Jie; Zhong, Hongying

    2016-01-28

    A rapid and solvent free substitution reaction of a fluorine atom in perfluorooctane sulfonyl fluoride (PFOSF) with a hydroxyl radical is reported. Under irradiation of ultraviolet laser on semiconductor nanoparticles or metal surfaces, hydroxyl radicals can be generated through hole oxidization. Among all fluorine atoms of PFOSF, highly active hydroxyl radicals specifically substitute the fluorine of sulfonyl fluoride functional group. Resultant perfluorooctane sulfonic acid is further ionized through capture of photo-generated electrons that switch the neutral molecules to negatively charged odd electron hypervalent ions. The unpaired electron subsequently initiates α O-H bond cleavage and produces perfluorooctane sulfonate negative ions. Hydroxyl radical substitution and molecular dissociation of PFOSF have been confirmed by masses with high accuracy and resolution. It has been applied to direct mass spectrometric imaging of PFOSF adsorbed on surfaces of plant leaves.

  11. Atmospheric pressure flow reactor / aerosol mass spectrometer studies of tropospheric aerosol nucleat and growth kinetics. Final report, June, 2001

    SciTech Connect

    Worsnop, Douglas R.

    2001-06-01

    The objective of this program was to determine the mechanisms and rates of growth and transformation and growth processes that control secondary aerosol particles in both the clear and polluted troposphere. The experimental plan coupled an aerosol mass spectrometer (AMS) with a chemical ionization mass spectrometer to provide simultaneous measurement of condensed and particle phases. The first task investigated the kinetics of tropospheric particle growth and transformation by measuring vapor accretion to particles (uptake coefficients, including mass accommodation coefficients and heterogeneous reaction rate coefficients). Other work initiated investigation of aerosol nucleation processes by monitoring the appearance of submicron particles with the AMS as a function of precursor gas concentrations. Three projects were investigated during the program: (1) Ozonolysis of oleic acid aerosols as model of chemical reactivity of secondary organic aerosol; (2) Activation of soot particles by measurement deliquescence in the presence of sulfuric acid and water vapor; (3) Controlled nucleation and growth of sulfuric acid aerosols.

  12. Mass size distributions of elemental aerosols in industrial area.

    PubMed

    Moustafa, Mona; Mohamed, Amer; Ahmed, Abdel-Rahman; Nazmy, Hyam

    2015-11-01

    Outdoor aerosol particles were characterized in industrial area of Samalut city (El-minia/Egypt) using low pressure Berner cascade impactor as an aerosol sampler. The impactor operates at 1.7 m(3)/h flow rate. Seven elements were investigated including Ca, Ba, Fe, K, Cu, Mn and Pb using atomic absorption technique. The mean mass concentrations of the elements ranged from 0.42 ng/m(3) (for Ba) to 89.62 ng/m(3) (for Fe). The mass size distributions of the investigated elements were bi-modal log normal distribution corresponding to the accumulation and coarse modes. The enrichment factors of elements indicate that Ca, Ba, Fe, K, Cu and Mn are mainly emitted into the atmosphere from soil sources while Pb is mostly due to anthropogenic sources.

  13. ESR and mass-spectrometric uranium-series dating studies of a mammoth tooth from stanton harcourt, Oxfordshire, England

    NASA Astrophysics Data System (ADS)

    Zhou, L. P.; McDermott, F.; Rhodes, E. J.; Marseglia, E. A.; Mellars, P. A.

    The age of the Channel Deposits at Stanton Harcourt, Oxfordshire, England, has been a topic of debate with important implications for British Pleistocene stratigraphy. Recent excavations led by K. Scott reveal ample evidence for ancient environmental conditions characteristic of an interglacial. However, the question remains on the assignment of its age. At present it is thought to represent an interglacial corresponding to either marine OI Stage 7 or 5e. In an attempt to constrain the chronology of the site, and to assess the techniques' reliability, we have made electron spin resonance (ESR) measurements on enamel and mass-spectrometric U-series measurements on both enamel and dentine from a mammoth tooth buried in the Channel Deposits at Stanton Harcourt. Four dentine samples gave U-series dates between 65.4±0.4 and 146.5±1.0 ka and two enamel samples between these dentine layers were dated to 53.3±0.2 and 61.1±0.6 ka. The corresponding ESR age estimates for the enamel samples are 59±6 and 62±4 ka (early U-uptake, EU) and 95±11 and 98±7 ka (linear U-uptake, LU). The recent U-uptake (RU) dates are 245±38 and 238±31 ka, but in light of the U-series data we would not expect these to represent realistic age estimates. Similar ESR results were obtained from two other adjacent enamel samples. The effect of the large size of the mammoth tooth on the external gamma dose, and the internal gamma contribution from the high U content of the dentine, are considered. While the recent uptake ESR dates appear to coincide with OI Stage 7, all the early and linear uptake ESR and mass-spectrometric U-series dates are younger than the expected age estimation based on recent geological interpretation and amino acid racemisation measurements (>200 ka) and optical dating studies (200-450 ka). Possible causes of the unexpected dating results are discussed. We conclude that our mass-spectrometric U-series and EU and LU ESR measurements represent minimum age estimates for the

  14. INTERLABORATORY STUDY OF A THERMOSPRAY-LIQUID CHROMATOGRAPHIC/MASS SPECTROMETRIC METHOD FOR SELECTED N-METHYL CARBAMATES, N-METHYL CARBAMOYLOXIMES, AND SUBSTITUTED UREA PESTICIDES

    EPA Science Inventory

    A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3-N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pestic...

  15. Utility of spatially-resolved atmospheric pressure surface sampling and ionization techniques as alternatives to mass spectrometric imaging (MSI) in drug metabolism

    SciTech Connect

    Blatherwick, Eleanor Q.; Van Berkel, Gary J; Pickup, Kathryn; Johansson, Maria K.; Beaudoin, Marie-Eve; Cole, Roderic; Day, Jennifer M.; Iverson, Suzanne; Wilson, Ian D.; Scrivens, James H.; Weston, Daniel J.

    2011-01-01

    1. Tissue distribution studies of drug molecules play an essential role in the pharmaceutical industry and are commonly undertaken using quantitative whole body autoradiography (QWBA) methods. 2. The growing need for complementary methods to address some scientific gaps around radiography methods has led to increased use of mass spectrometric imaging (MSI) technology over the last 5 to 10 years. More recently, the development of novel mass spectrometric techniques for ambient surface sampling has redefined what can be regarded as fit-for-purpose for MSI in a drug metabolism and disposition arena. 3. Together with a review of these novel alternatives, this paper details the use of two liquid microjunction (LMJ)- based mass spectrometric surface sampling technologies. These approaches are used to provide qualitative determination of parent drug in rat liver tissue slices using liquid extraction surface analysis (LESA) and to assess the performance of a LMJ surface sampling probe (LMJ-SSP) interface for quantitative assessment of parent drug in brain, liver and muscle tissue slices. 4. An assessment of the utility of these spatially-resolved sampling methods is given, showing interdependence between mass spectrometric and QWBA methods, in particular there emerges a reason to question typical MSI workflows for drug metabolism; suggesting the expedient use of profile or region analysis may be more appropriate, rather than generating time-intensive molecular images of the entire tissue section.

  16. Differentiation of the two major species of Echinacea (E. augustifolia and E. purpurea) using a flow injection mass spectrometric (FIMS) fingerprinting method and chemometric analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A rapid, simple, and reliable flow-injection mass spectrometric (FIMS) method was developed to discriminate two major Echinacea species (E. purpurea and E. angustifolia) samples. Fifty-eight Echinacea samples collected from United States were analyzed using FIMS. Principle component analysis (PCA) a...

  17. Differentiation of the four major types (C. Burmannii, C. Verum, C. cassia, And C. Loureiroi) of cinnamons using a flow-injection mass spectrometric (FIMS) fingerprinting method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple and efficient flow-injection mass spectrometric (FIMS) method was developed to differentiate cinnamon (Cinnamomum) bark (CB) samples of the four major species (C. burmannii, C. verum, C. aromaticum, and C. loureiroi) of cinnamon. Fifty cinnamon samples collected from China, Vietnam, Indon...

  18. Mass spectrometric 13C/12C determinations to detect high fructose corn syrup in orange juice: collaborative study.

    PubMed

    Doner, L W; Bills, D D; Carro, O; Drimmie, R; Fritz, P; Gearing, J N; Hillaire-Marcel, C; Parker, P L; Reeseman, F M; Smith, B N; Ziegler, H

    1982-05-01

    The 13C/12C ratios in orange juice are sufficiently uniform and different from those in high fructose corn syrup (HFCS) so that the addition of HFCS to orange juice can be detected. HFCS averages -9.7% (parts per thousand) delta 13C, orange juice averages -24.5%, and mixtures of HFCS and orange juice possess intermediate values. One pure orange juice and 4 orange juice -HFCS mixtures containing from 25 to 70% orange juice were properly classified by 7 collaborators. Samples with delta 13C values less negative than -22.1%, 4 standard deviations from the mean of pure juices, can, with a high degree of confidence, be classified as adulterated. Samples with values more negative than -22.1% must be considered unadulterated with HFCS, because pure orange juices possess a range of delta 13C values. The 13C/12C mass spectrometric method was adopted official first action for detecting HFCS in orange juice.

  19. Mass-spectrometric monitoring of the intravenous anesthetic concentration in the breathing circuit of an anesthesia machine

    NASA Astrophysics Data System (ADS)

    Elizarov, A. Yu.; Levshankov, A. I.

    2011-04-01

    Interaction between inhalational anesthetic sevoflurane and an absorber of CO2 (soda lime) in the breathing circuit of an anesthesia machine during low-flow anesthesia (0.5 l of a fresh gaseous mixture per minute) is studied with the mass-spectrometric method. Monitoring data for the concentration of sevoflurane and three toxic products of sevoflurane decompositions (substances A, B, and C) during anesthesia in the inspiration-expiration regime are presented. The highest concentration of substance A is found to be 65 ppm. The biochemical blood analysis before and after anesthesia shows that nephropathy is related to the function of liver toxicity. It is found that inhalational anesthetic sevoflurane influences the concentration of intravenous hypnotic propofol in blood.

  20. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein

    PubMed Central

    Zhang, Chongxu; Nielsen, Maria E. O.; Chiang, Yueh-Chin; Kierkegaard, Morten; Wang, Xin; Lee, Darren J.; Andersen, Jens S.; Yao, Gang

    2013-01-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from Saccharomyces cerevisiae. Because many of these factors may associate only indirectly with PAB1 by being components of the PAB1-mRNP structure, we additionally conducted mass spectrometric analyses on seven metabolically defined PAB1 deletion derivatives to delimit the interactions between these proteins and PAB1. These latter analyses identified 13 proteins whose associations with PAB1 were reduced by deleting one or another of PAB1’s defined domains. Included in this list of 13 proteins were the translation initiation factors eIF4G1 and eIF4G2, translation termination factor eRF3, and PBP2, all of whose previously known direct interactions with specific PAB1 domains were either confirmed, delimited, or extended. The remaining nine proteins that interacted through a specific PAB1 domain were CBF5, SLF1, UPF1, CBC1, SSD1, NOP77, yGR250c, NAB6, and GBP2. In further study, UPF1, involved in nonsense-mediated decay, was confirmed to interact with PAB1 through the RRM1 domain. We additionally established that while the RRM1 domain of PAB1 was required for UPF1-induced acceleration of deadenylation during nonsense-mediated decay, it was not required for the more critical step of acceleration of mRNA decapping. These results begin to identify the proteins most likely to interact with PAB1 and the domains of PAB1 through which these contacts are made. PMID:22836166

  1. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein.

    PubMed

    Richardson, Roy; Denis, Clyde L; Zhang, Chongxu; Nielsen, Maria E O; Chiang, Yueh-Chin; Kierkegaard, Morten; Wang, Xin; Lee, Darren J; Andersen, Jens S; Yao, Gang

    2012-09-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from Saccharomyces cerevisiae. Because many of these factors may associate only indirectly with PAB1 by being components of the PAB1-mRNP structure, we additionally conducted mass spectrometric analyses on seven metabolically defined PAB1 deletion derivatives to delimit the interactions between these proteins and PAB1. These latter analyses identified 13 proteins whose associations with PAB1 were reduced by deleting one or another of PAB1's defined domains. Included in this list of 13 proteins were the translation initiation factors eIF4G1 and eIF4G2, translation termination factor eRF3, and PBP2, all of whose previously known direct interactions with specific PAB1 domains were either confirmed, delimited, or extended. The remaining nine proteins that interacted through a specific PAB1 domain were CBF5, SLF1, UPF1, CBC1, SSD1, NOP77, yGR250c, NAB6, and GBP2. In further study, UPF1, involved in nonsense-mediated decay, was confirmed to interact with PAB1 through the RRM1 domain. We additionally established that while the RRM1 domain of PAB1 was required for UPF1-induced acceleration of deadenylation during nonsense-mediated decay, it was not required for the more critical step of acceleration of mRNA decapping. These results begin to identify the proteins most likely to interact with PAB1 and the domains of PAB1 through which these contacts are made.

  2. A microchip electrophoresis-mass spectrometric platform with double cell lysis nano-electrodes for automated single cell analysis.

    PubMed

    Li, Xiangtang; Zhao, Shulin; Hu, Hankun; Liu, Yi-Ming

    2016-06-17

    Capillary electrophoresis-based single cell analysis has become an essential approach in researches at the cellular level. However, automation of single cell analysis has been a challenge due to the difficulty to control the number of cells injected and the irreproducibility associated with cell aggregation. Herein we report the development of a new microfluidic platform deploying the double nano-electrode cell lysis technique for automated analysis of single cells with mass spectrometric detection. The proposed microfluidic chip features integration of a cell-sized high voltage zone for quick single cell lysis, a microfluidic channel for electrophoretic separation, and a nanoelectrospray emitter for ionization in MS detection. Built upon this platform, a microchip electrophoresis-mass spectrometric method (MCE-MS) has been developed for automated single cell analysis. In the method, cell introduction, cell lysis, and MCE-MS separation are computer controlled and integrated as a cycle into consecutive assays. Analysis of large numbers of individual PC-12 neuronal cells (both intact and exposed to 25mM KCl) was carried out to determine intracellular levels of dopamine (DA) and glutamic acid (Glu). It was found that DA content in PC-12 cells was higher than Glu content, and both varied from cell to cell. The ratio of intracellular DA to Glu was 4.20±0.8 (n=150). Interestingly, the ratio drastically decreased to 0.38±0.20 (n=150) after the cells are exposed to 25mM KCl for 8min, suggesting the cells released DA promptly and heavily while they released Glu at a much slower pace in response to KCl-induced depolarization. These results indicate that the proposed MCE-MS analytical platform may have a great potential in researches at the cellular level.

  3. A new method for estimating aerosol mass flux in the urban surface layer using LAS technology

    NASA Astrophysics Data System (ADS)

    Yuan, Renmin; Luo, Tao; Sun, Jianning; Liu, Hao; Fu, Yunfei; Wang, Zhien

    2016-04-01

    Atmospheric aerosol greatly influences human health and the natural environment, as well as the weather and climate system. Therefore, atmospheric aerosol has attracted significant attention from society. Despite consistent research efforts, there are still uncertainties in understanding its effects due to poor knowledge about aerosol vertical transport caused by the limited measurement capabilities of aerosol mass vertical transport flux. In this paper, a new method for measuring atmospheric aerosol vertical transport flux is developed based on the similarity theory of surface layer, the theory of light propagation in a turbulent atmosphere, and the observations and studies of the atmospheric equivalent refractive index (AERI). The results show that aerosol mass flux can be linked to the real and imaginary parts of the atmospheric equivalent refractive index structure parameter (AERISP) and the ratio of aerosol mass concentration to the imaginary part of the AERI. The real and imaginary parts of the AERISP can be measured based on the light-propagation theory. The ratio of the aerosol mass concentration to the imaginary part of the AERI can be measured based on the measurements of aerosol mass concentration and visibility. The observational results show that aerosol vertical transport flux varies diurnally and is related to the aerosol spatial distribution. The maximum aerosol flux during the experimental period in Hefei City was 0.017 mg m-2 s-1, and the mean value was 0.004 mg m-2 s-1. The new method offers an effective way to study aerosol vertical transport in complex environments.

  4. Identification and Characterization of Biogenic SOA Component in Ambient Aerosols Based on Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Jimenez, J.; Allan, J. D.; Kiendler-Scharr, A.; Tian, J.; Canagaratna, M. R.; Williams, B.; Worsnop, D. R.; Coe, H.; Goldstein, A.; Mentel, T. F.

    2008-12-01

    Recently studies have shown that multivariate factor analysis of the highly time-resolved mass spectral data obtained with an Aerodyne Aerosol Mass Spectrometer (AMS) may allow the classification and simplification of complex organic aerosol (OA) mixtures into components that are chemically meaningful and can be related to different sources and transformation processes. Two factor analysis techniques, including the Multiple Component Analysis (MCA) method (Zhang et al., 2007) and the Positive Matrix Factorization (PMF) method (Paatero and Tapper, 1994), were applied to a Quadrupole-AMS dataset acquired from Chebogue Pt., Nova Scotia in summer 2004. Multiple OA components were determined, including a hydrocarbon-like OA (HOA) component similar in mass spectra to the hydrocarbon substances observed at urban locations and two oxygenated OA (OA) components that show different fragmentation patterns and oxygen-to-carbon ratios in their mass spectra. The HOA component correlates with inert primary emission tracers (e.g., EC and CO) and likely represents diluted POA transported from urban locations. The highly oxygenated component (OOA-I) correlates well with sulfate and shows a mass spectrum resembling that of fulvic acid - a model compound representative for highly processed/oxidized organics in the environment. The less oxygenated OA component (OOA-II) reveals a mass spectral pattern that compares well with those of the biogenic SOA produced from the mixture of VOCs emitted by spruce, pine and birch trees during exposure to ozone and UV-photolysis in the Jülich plant chamber. In addition, the time series of OOA-II correlates with biogenic SOA tracer compounds determined by the thermal desorption aerosol GC/MS-FID (TAG) instrument. Furthermore, the time-resolved size distributions of OOA components, their correlations with parallel gas and aerosol measurements, and backtrajectory analysis of air masses all support the association of OOA-II to biogenic sources. Finally

  5. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; Prévôt, A. S. H.; El Haddad, I.

    2015-08-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make impractical its deployment at sufficient sites to determine regional characteristics. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, PM10) collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g. AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 μg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon, oxygen containing and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g. filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially-resolved long-term datasets.

  6. Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Daellenbach, K. R.; Bozzetti, C.; Křepelová, A.; Canonaco, F.; Wolf, R.; Zotter, P.; Fermo, P.; Crippa, M.; Slowik, J. G.; Sosedova, Y.; Zhang, Y.; Huang, R.-J.; Poulain, L.; Szidat, S.; Baltensperger, U.; El Haddad, I.; Prévôt, A. S. H.

    2016-01-01

    Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60-91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

  7. Characterization of aerosol composition and sources in the greater Atlanta area by aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Ng, N. L.; Xu, L.; Suresh, S.; Weber, R. J. J.; Baumann, K.; Edgerton, E. S.

    2014-12-01

    An important and uncertain aspect of biogenic secondary organic aerosol (SOA) formation is that it is often associated with anthropogenic pollution tracers. Prior studies in Atlanta suggested that 70-80% of the carbon in water-soluble organic carbon (WSOC) is modern, yet it is well-correlated with the anthropogenic CO. In this study, we deployed a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and an Aerosol Chemical Speciation Monitor (ACSM) at multiple sites in different seasons (May 2012-February 2013) to characterize the sources and chemical composition of aerosols in the greater Atlanta area. This area in the SE US is ideal to investigate anthropogenic-biogenic interactions due to high natural and anthropogenic emissions. These extensive field studies are part of the Southeastern Center for Air Pollution and Epidemiology study (SCAPE). The HR-ToF-AMS is deployed at four sites (~ 3 weeks each) in rotation: Jefferson Street (urban), Yorkville (rural), roadside site (near Highway 75/85), and Georgia Tech site (campus), with the urban and rural sites being part of the SEARCH network. We obtained seven HR-ToF-AMS datasets in total. During the entire measurement period, the ACSM is stationary at the GIT site and samples continuously. We perform positive matrix factorization (PMF) analysis on the HR-ToF-AMS and ACSM data to deconvolve the OA into different components. While the diurnal cycle of the total OA is flat as what have been previously observed, the OA factors resolved by PMF analysis show distinctively different diurnal trends. We find that the "more-oxidized oxygenated OA" (MO-OOA) constitutes a major fraction of OA at all sites. In summer, OA is dominated by SOA, e.g., isoprene-OA and OOA with different degrees of oxidation. In contrary, biomass burning OA is more prominent in winter data. By comparing HR-ToF-AMS and ACSM data during the same sampling periods, we find that the aerosol time series are highly correlated, indicating the

  8. Mass Spectrometry of Atmospheric Aerosol: 1 nanometer to 1 micron

    NASA Astrophysics Data System (ADS)

    Worsnop, D. R.; Ehn, M.; Junninen, H.; Kulmala, M. T.

    2010-12-01

    The role of aerosol particles remains the largest uncertainty in quantitatively assessing past, current and future climate change. The principal reason for that uncertainty arises from the need to characterize and model composition and size dependent aerosol processes, ranging from nanometer to micron scales. Aerosol mass spectrometry results have shown that about half the sub-micron aerosol composition is composed of highly oxygenated organics that are not well understood in terms of photochemical reaction mechanisms (Jimenez et al, 2009). This work has included application of high resolution time-of-flight mass spectrometry (ToFMS) in order to determine elemental and functional group composition of complex organic components. Recently, we have applied similar ToFMS to determine the composition of ambient ions, molecules and clusters, potentially involved in formation and growth of nano-particles (Junninen et al, 2010). Observed organic anions (molecular weight range 200-500 Th) have similar chemical composition as the least volatile secondary organics observed in fine particles; while organic cations are dominated by amines and pyridines. During nucleation events, anions are dominated by sulphuric acid cluster ions (Ehn et al, 2010). In both nanometer and micrometer size ranges, the goal to elucidate the roles of inorganic and organic species, particularly how particle evolution and physical properties depend on mixed compositions. Recent results will be discussed, including ambient and experimental chamber observations. Ehn et al, Atmos. Chem. Phys. Discuss., 10, 14897-14946, 2010 Jimenez et al, Science, 326, 1525-1529, 2009 Junninen et al, Atmos. Meas. Tech., 3, 1039-1053, 2010

  9. A new code for spectrometric analysis for environmental radiological surveillance on monitors focused on gamma radioactivity on aerosols

    SciTech Connect

    De Blas, Alfredo; Tapia, Carlos; Riego, Albert; Garcia, Roger; Dies, Javier; Diaz, Pedro; Toral, Juan; Batalla, Enric

    2015-07-01

    pGamma is a code developed by the NERG group of the Technical University of Catalonia - Barcelona Tech for the analysis of gamma spectra generated by the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols with Paper Filter developed for our group and Raditel Servies company. Nowadays the code is in the process of adaptation for the monitors of the Environmental Radiological Surveillance Network of the Local Government of Catalonia (Generalitat of Catalonia), Spain. The code is a Spectrum Analysis System, it identifies the gamma emitters on the spectrum, determines its Concentration of Activity, generates alarms depending on the Activity of the emitters and generates a report. The Spectrum Analysis System includes a library with emitters of interest, NORM and artificial. The code is being used on the three stations with the aerosol monitor of the Network (Asco and Vandellos, near both Nuclear Power Plants and Barcelona). (authors)

  10. Investigating types and sources of organic aerosol in Rocky Mountain National Park using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schurman, M. I.; Lee, T.; Sun, Y.; Schichtel, B. A.; Kreidenweis, S. M.; Collett, J. L., Jr.

    2015-01-01

    The environmental impacts of atmospheric particles are highlighted in remote areas where visibility and ecosystem health can be degraded by even relatively low particle concentrations. Submicron particle size, composition, and source apportionment were explored at Rocky Mountain National Park using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer. This summer campaign found low average, but variable, particulate mass (PM) concentrations (max = 93.1 μg m-3, avg. = 5.13 ± 2.72 μg m-3) of which 75.2 ± 11.1% is organic. Low-volatility oxidized organic aerosol (LV-OOA, 39.3% of PM1 on average) identified using Positive Matrix Factorization appears to be mixed with ammonium sulfate (3.9% and 16.6% of mass, respectively), while semi-volatile OOA (27.6%) is correlated with ammonium nitrate (nitrate: 4.3%); concentrations of these mixtures are enhanced with upslope (SE) surface winds from the densely populated Front Range area, indicating the importance of transport. A local biomass burning organic aerosol (BBOA, 8.4%) source is suggested by mass spectral cellulose combustion markers (m/z 60 and 73) limited to brief, high-concentration, polydisperse events (suggesting fresh combustion), a diurnal maximum at 22:00 local standard time when campfires were set at adjacent summer camps, and association with surface winds consistent with local campfire locations. The particle characteristics determined here represent typical summertime conditions at the Rocky Mountain site based on comparison to ~10 years of meteorological, particle composition, and fire data.

  11. Investigating types and sources of organic aerosol in Rocky Mountain National Park using aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schurman, M. I.; Lee, T.; Sun, Y.; Schichtel, B. A.; Kreidenweis, S. M.; Collett, J. L., Jr.

    2014-07-01

    The environmental impacts of atmospheric particles are highlighted in remote areas where visibility and ecosystem health can be degraded by even relatively low particle concentrations. Submicron particle size, composition, and source apportionment were explored at Rocky Mountain National Park using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer. This summer campaign found low average, but variable, particulate mass (PM) concentrations (max = 93.1 μg m-3, avg. = 5.13 ± 2.72 μg m-3) of which 75.2 ± 11.1% is organic. Low-volatility oxidized organic aerosol (LV-OOA, 39.3% of PM1 on average) identified using Positive Matrix Factorization appears to be mixed with ammonium sulfate (3.9 and 16.6% of mass, respectively), while semi-volatile OOA (27.6%) is correlated with ammonium nitrate (nitrate: 4.3%); concentrations of these mixtures are enhanced with upslope (SE) surface winds from the densely populated Front Range area, indicating the importance of transport. A local biomass burning organic aerosol (BBOA, 8.4%) source is suggested by mass spectral cellulose combustion markers (m/zs 60 and 73) limited to brief, high-concentration, polydisperse events (suggesting fresh combustion), a diurnal maximum at 22:00 local standard time (LST) when campfires were set at adjacent summer camps, and association with surface winds consistent with local campfire locations. The particle characteristics determined here represent typical summertime conditions at the Rocky Mountain site based on comparison to ∼10 years of meteorological, particle composition, and fire data.

  12. Distribution of coniferin in differentiating normal and compression woods using MALDI mass spectrometric imaging coupled with osmium tetroxide vapor treatment.

    PubMed

    Yoshinaga, Arata; Kamitakahara, Hiroshi; Takabe, Keiji

    2016-05-01

    Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to detect monolignol glucosides in differentiating normal and compression woods of two Japanese softwoods, Chamaecyparis obtusa and Cryptomeria japonica Comparison of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry collision-induced dissociation fragmentation analysis and structural time-of-flight (MALDI-TOF CID-FAST) spectra between coniferin and differentiating xylem also confirmed the presence of coniferin in differentiating xylem. However, as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF CID-FAST spectra of sucrose were similar to those of coniferin, it was difficult to distinguish the distribution of coniferin and sucrose using MALDI-MSI and collision-induced dissociation measurement only. To solve this problem, osmium tetroxide vapor was applied to sections of differentiating xylem. This vapor treatment caused peak shifts corresponding to the introduction of two hydroxyl groups to the C=C double bond in coniferin. The treatment did not cause a peak shift for sucrose, and therefore was effective in distinguishing coniferin and sucrose. Thus, it was found that MALDI-MSI combined with osmium tetroxide vapor treatment is a useful method to detect coniferin in differentiating xylem.

  13. Direct evaluation of aerosol-mass loadings from multispectral extinction data

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Mckellar, B. H. J.

    1978-01-01

    A formula is derived for the evaluation of the total volume of aerosol in a column, and hence for the aerosol columnar mass loading, from multispectral extinction data. This formula is exact in the 'anomalous diffraction' approximation, and reasonably accurate for Mie scattering, over a fairly wide range of refractive indices typical of real aerosols.

  14. A NEW MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING TRACE-LEVEL ORGANIC COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory



    Most organic compounds are not found in mass spectral libraries and cannot be easily identified from low resolution mass spectra. Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer in a new way to determine exact mas...

  15. A CLOSURE STUDY OF AEROSOL MASS CONCENTRATION MEASUREMENTS: COMPARISON OF VALUES OBTAINED WITH FILTERS AND BY DIRECT MEASUREMENTS OF MASS DISTRIBUTIONS. (R826372)

    EPA Science Inventory

    We compare measurements of aerosol mass concentrations obtained gravimetrically using Teflon coated glass fiber filters and by integrating mass distributions measured with the differential mobility analyzer–aerosol particle mass analyzer (DMA–APM) technique (Aero...

  16. Mass absorption indices of various types of natural aerosol particles in the infrared.

    PubMed

    Fischer, K

    1975-12-01

    The mass absorption index of aerosol particles has been measured in the 2-17-microm wavelength region. The measurements were performed on films of aerosol particles that were collected by an automatic jet impactor at polluted and various uncontaminated remote sites. All but marine aerosols possess strong absorption bands in the transparent part of the atmospheric long-wave spectrum, indicating marked influence of aerosol particles on the radiation budget of the atmosphere.

  17. Quantitative determination of total methamphetamine and active metabolites in rat tissue by liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Hendrickson, Howard; Laurenzana, Elizabeth; Owens, S Michael

    2006-11-22

    High-throughput liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) methodology for the determination of methamphetamine (METH), amphetamine (AMP), 4-hydroxymethamphetamine (4-OH-METH), and 4-hydroxyamphetamine (4-OH-AMP) was developed and validated using simple trichloroacetic acid sample treatment. The method was validated in rat serum, brain, and testis. Lower limits-of-quantitation (LOQ) for METH and AMP were 1 ng x mL(-1) using positive ion electrospray tandem mass spectrometry (MS/MS). The accuracy of the method was within 25% of the actual values over a wide range of analyte concentrations. The within-assay precision was better than 12% (coefficient of variation). The method was linear over a wide dynamic range (0.3-1000 ng x mL(-1)). Quantitation was possible in all 3 matrices using only serum standards because of minimal matrix-associated ion effects or the use of an internal standard. Finally, the LC-MS/MS method was used to determine serum, brain, and testis METH and AMP concentrations during a subcutaneous infusion (5.6 mg kg(-1) day(-1)) of METH in rats. Concentrations of 4-OH-AMP and 4-OH-METH were below the LOQ in experimental samples. The bias introduced by using serum calibrators for the determination of METH and AMP concentrations in testis and brain was less than 8% and insignificant relative to the interanimal variability.

  18. Simultaneous determination of oxygen, nitrogen and hydrogen in metals by pulse heating and time of flight mass spectrometric method.

    PubMed

    Shen, Xuejing; Wang, Peng; Hu, Shaocheng; Yang, Zhigang; Ma, Hongquan; Gao, Wei; Zhou, Zhen; Wang, Haizhou

    2011-05-30

    The inert gas fusion and infrared absorption and thermal conductivity methods are widely used for quantitative determination of oxygen(O), nitrogen(N) and hydrogen(H) in metals. However, O, N and H cannot be determined simultaneously with this method in most cases and the sensitivity cannot meet the requirement of some new metal materials. Furthermore, there is no equipment or method reported for determination of Argon(Ar) or Helium(He) in metals till now. In this paper, a new method for simultaneous quantitative determination of O, N, H and Ar(or He) in metals has been described in detail, which combined the pulse heating inert gas fusion with time of flight mass spectrometric detection. The whole analyzing process was introduced, including sample retreatment, inert gas fusion, mass spectral line selection, signal acquisition, data processing and calibration. The detection limit, lower quantitative limit and linear range of each element were determined. The accuracy and precision of the new method have also been verified by measurements of several kinds of samples. The results were consistent with that obtained by the traditional method. It has shown that the new method is more sensitive and efficient than the existing method.

  19. Mono-, di- and trimethylated homologues of isoprenoid tetraether lipid cores in archaea and environmental samples: mass spectrometric identification and significance.

    PubMed

    Knappy, Chris; Barillà, Daniela; Chong, James; Hodgson, Dominic; Morgan, Hugh; Suleman, Muhammad; Tan, Christine; Yao, Peng; Keely, Brendan

    2015-12-01

    Higher homologues of widely reported C(86) isoprenoid diglycerol tetraether lipid cores, containing 0-6 cyclopentyl rings, have been identified in (hyper)thermophilic archaea, representing up to 21% of total tetraether lipids in the cells. Liquid chromatography-tandem mass spectrometry confirms that the additional carbon atoms in the C(87-88) homologues are located in the etherified chains. Structures identified include dialkyl and monoalkyl ('H-shaped') tetraethers containing C(40-42) or C(81-82) hydrocarbons, respectively, many representing novel compounds. Gas chromatography-mass spectrometric analysis of hydrocarbons released from the lipid cores by ether cleavage suggests that the C(40) chains are biphytanes and the C(41) chains 13-methylbiphytanes. Multiple isomers, having different chain combinations, were recognised among the dialkyl lipids. Methylated tetraethers are produced by Methanothermobacter thermautotrophicus in varying proportions depending on growth conditions, suggesting that methylation may be an adaptive mechanism to regulate cellular function. The detection of methylated lipids in Pyrobaculum sp. AQ1.S2 and Sulfolobus acidocaldarius represents the first reported occurrences in Crenarchaeota. Soils and aquatic sediments from geographically distinct mesotemperate environments that were screened for homologues contained monomethylated tetraethers, with di- and trimethylated structures being detected occasionally. The structural diversity and range of occurrences of the C(87-89) tetraethers highlight their potential as complementary biomarkers for archaea in natural environments.

  20. Improved matrix-assisted laser desorption/ionization mass spectrometric detection of glycosaminoglycan disaccharides as cesium salts.

    PubMed

    Laremore, Tatiana N; Linhardt, Robert J

    2007-01-01

    Ultraviolet matrix-assisted laser desorption/ionization mass spectrometric (UV-MALDI-MS) analysis of highly acidic, thermally labile species such as glycosaminoglycan-derived oligosaccharides is complicated by their poor ionization efficiency and tendency to fragment through the loss of sulfo groups. We have utilized a systematic approach to evaluate the effect of alkali metal counterions on the degree of fragmentation through SO3 loss from a highly sulfated model compound, sucrose octasulfate (SOS). The lithium, sodium, potassium, rubidium, and cesium salts of SOS were analyzed by UV-MALDI-time-of-flight (TOF)MS using an ionic liquid matrix, bis-1,1,3,3-tetramethylguanidinium alpha-cyano-4-hydroxycinnamate. The positive-ion and negative-ion MALDI mass spectra of five alkali metal salts of SOS were compared in terms of the degree of analyte fragmentation through the SO3 loss and the absolute intensity of a molecular ion signal. Experimental results demonstrate that the lithium, sodium, and potassium salts of SOS undergo some degree of fragmentation through the loss of SO3, whereas the fragmentation through the loss of SO3 in the rubidium and cesium salts of SOS is suppressed. A high detection sensitivity associated with the stability of sulfate half-esters was achieved for the cesium salt of SOS using positive-ion detection. Finally, the cesium salt of chondroitin sulfate A disaccharide was successfully analyzed using UV-MALDI-TOFMS.

  1. QuEChERS multiresidue method validation and mass spectrometric assessment for the novel anthranilic diamide insecticides chlorantraniliprole and cyantraniliprole.

    PubMed

    Schwarz, Timo; Snow, Timothy A; Santee, Christopher J; Mulligan, Christopher C; Class, Thomas; Wadsley, Michael P; Nanita, Sergio C

    2011-02-09

    The gas-phase dissociation reactions of chlorantraniliprole (Rynaxypyr) and cyantraniliprole (Cyazypyr) have been studied in triple-quadrupole, ion trap, and orbitrap mass spectrometers equipped with electrospray and desorption electrospray ion sources, revealing the formation of odd-electron fragment ions, the structures of which were elucidated. The odd-electron fragments were unusually abundant, and their formation is proposed to occur via a tricyclic intermediate. The applicability of the QuEChERS multiresidue method for the quantitation of chlorantraniliprole and cyantraniliprole was also assessed in this study. Four matrices representative of oily, watery, acidic, and dry crop groups were tested, with a targeted limit of quantitation (LOQ) of 0.01 mg/kg. Average recoveries ranged between 87 and 107%, with relative standard deviations (RSD) of ≤ 8%. Linear calibration functions with correlation coefficients r > 0.99 were obtained. The study provides an expansion of the QuEChERS method to include anthranilic diamides and a mass spectrometric assessment for these two novel agrochemical active ingredients.

  2. Mass Spectrometric N-Glycan Analysis of Haptoglobin from Patient Serum Samples Using a 96-Well Plate Format.

    PubMed

    Zhu, Jianhui; Wu, Jing; Yin, Haidi; Marrero, Jorge; Lubman, David M

    2015-11-06

    Alterations in glycosylation of serum glycoproteins can provide unique and highly specific fingerprints of malignancy. Our previous mass spectrometric study revealed that the bifucosylation level of serum haptoglobin was distinctly increased in hepatocellular carcinoma (HCC) patients versus liver cirrhosis of all three major etiologies. We have thus developed a method for the analysis of large numbers of serum samples based on a 96-well plate platform for the evaluation of fucosylation changes of serum haptoglobin between HCC versus cirrhosis. Haptoglobin was isolated from the serum of individual patient samples based on an HPLC column immobilized with antihaptoglobin antibody via hydrazide immobilization chemistry. Only 10 μL of serum was required for glycan extraction and processing for MALDI-QIT mass spectrometry analysis using the 96-well plate format. The bifucosylation degrees of haptoglobin in individuals were calculated using a quantitative glycomics method. The MS data confirmed that the bifucosylated tetra-anntenary glycan was upregulated in HCC samples of all etiologies. This study provides a parallel method for processing glycan content for haptoglobin and evaluating detailed changes in glycan structures for a potentially large cohort of clinical serum samples.

  3. Advanced Mass Spectrometric Methods for the Rapid and Quantitative Characterization of Proteomes

    DOE PAGES

    Smith, Richard D.

    2002-01-01

    Progress is reviewedmore » towards the development of a global strategy that aims to extend the sensitivity, dynamic range, comprehensiveness and throughput of proteomic measurements based upon the use of high performance separations and mass spectrometry. The approach uses high accuracy mass measurements from Fourier transform ion cyclotron resonance mass spectrometry (FTICR) to validate peptide ‘accurate mass tags’ (AMTs) produced by global protein enzymatic digestions for a specific organism, tissue or cell type from ‘potential mass tags’ tentatively identified using conventional tandem mass spectrometry (MS/MS). This provides the basis for subsequent measurements without the need for MS/ MS. High resolution capillary liquid chromatography separations combined with high sensitivity, and high resolution accurate FTICR measurements are shown to be capable of characterizing peptide mixtures of more than 10 5 components. The strategy has been initially demonstrated using the microorganisms Saccharomyces cerevisiae and Deinococcus radiodurans. Advantages of the approach include the high confidence of protein identification, its broad proteome coverage, high sensitivity, and the capability for stableisotope labeling methods for precise relative protein abundance measurements. Abbreviations : LC, liquid chromatography; FTICR, Fourier transform ion cyclotron resonance; AMT, accurate mass tag; PMT, potential mass tag; MMA, mass measurement accuracy; MS, mass spectrometry; MS/MS, tandem mass spectrometry; ppm, parts per million.« less

  4. Characterization of organic aerosols in Beijing using an aerodyne high-resolution aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Junke; Wang, Yuesi; Huang, Xiaojuan; Liu, Zirui; Ji, Dongsheng; Sun, Yang

    2015-06-01

    Fine particle of organic aerosol (OA), mostly arising from pollution, are abundant in Beijing. To achieve a better understanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Research Inc., USA) was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30±30 μg m-3, which was higher than in summer (13±6.9 μg m-3). The elemental analysis found that OA was more aged in summer (oxygen-to-carbon (O/C) ratios were 0.41 and 0.32 for summer and autumn, respectively). Positive matrix factorization (PMF) analysis identified three and five components in summer and autumn, respectively. In summer, an oxygenated OA (OOA), a cooking-emission-related OA (COA), and a hydrocarbon-like OA (HOA) were indentified. Meanwhile, the OOA was separated into LV-OOA (low-volatility OOA) and SV-OOA (semi-volatile OOA); and in autumn, a nitrogen-containing OA (NOA) was also found. The SOA (secondary OA) was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components, especially the POA (primary OA), in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.

  5. Laboratory and field measurements of organic aerosols with the photoionization aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Dreyfus, Matthew A.

    Analytical methods developed to sample and characterize ambient organic aerosols often face the trade-off between long sampling times and the loss of detailed information regarding specific chemical species present. The soft, universal ionization scheme of the Photoionization Aerosol Mass Spectrometer (PIAMS) allows for identification of various chemical compounds by a signature ion, often the molecular ion. The goal of this thesis work is to apply PIAMS to both laboratory and field experiments to answer questions regarding the formation, composition, and behavior of organic aerosols. To achieve this goal, a variety of hardware and software upgrades were administered to PIAMS to optimize the instrument. Data collection and processing software were either refined or built from the ground up to simplify difficult or monotonous tasks. Additional components were added to PIAMS with the intent to automate the instrument, enhance the results, and make the instrument more rugged and user-friendly. These changes, combined with the application of an external particle concentration system (mini-Versatile Aerosol Concentration Enrichment System, m-VACES), allowed PIAMS to be suitable for field measurements of organic aerosols. Two such field campaigns were completed, both at the State of Delaware Air Quality Monitoring Site in Wilmington, Delaware: a one week period in June, 2006, and an 18 day period in October and November of 2007. A sampling method developed was capable of collecting sufficient ambient organic aerosol and analyzing it with a time resolution of 3.5 minutes. Because of this method, short term concentration changes of individual species can be tracked. Combined with meteorological data, the behavior of these species can be analyzed as a function of time or wind direction. Many compounds are found at enhanced levels during the evening/night-time hours; potentially due to the combined effects of temperature inversion, and fresh emissions in a cooler environment

  6. Towards depth profiling of organic aerosols in real time using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Hoffmann, Thorsten

    2014-05-01

    Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a

  7. Synthesis, purification and mass spectrometric characterisation of a fluorescent Au9@BSA nanocluster and its enzymatic digestion by trypsin

    NASA Astrophysics Data System (ADS)

    Fernández-Iglesias, Nerea; Bettmer, Jörg

    2013-12-01

    Nanoclusters of noble metals like Ag and Au have attracted great attention as they form a missing link between isolated metal atoms and nanoparticles. Their particular properties like luminescence in the visible range and nontoxicity make them attractive for bioimaging and biolabelling purposes, especially with use of proteins as stabilising agents. In this context, this study intends the synthesis of a specific Au nanocluster covered by bovine serum albumin (BSA). It is shown that size-exclusion chromatography is feasible for the purification and isolation of the nanocluster. A mass spectrometric characterisation, preferably by ESI-MS, indicates the presence of an Au9@BSA nanocluster. Enzymatic digestion of the nanocluster with trypsin results in a significant increase of the fluorescence intensity at 650 and 710 nm, whereas complementary MALDI-MS studies are presented for the identification of generated peptides and show a distinctive pattern in comparison to the pure protein. It can be concluded that Au9@BSA might be, in future, an interesting candidate for in vitro studies of protease activities.Nanoclusters of noble metals like Ag and Au have attracted great attention as they form a missing link between isolated metal atoms and nanoparticles. Their particular properties like luminescence in the visible range and nontoxicity make them attractive for bioimaging and biolabelling purposes, especially with use of proteins as stabilising agents. In this context, this study intends the synthesis of a specific Au nanocluster covered by bovine serum albumin (BSA). It is shown that size-exclusion chromatography is feasible for the purification and isolation of the nanocluster. A mass spectrometric characterisation, preferably by ESI-MS, indicates the presence of an Au9@BSA nanocluster. Enzymatic digestion of the nanocluster with trypsin results in a significant increase of the fluorescence intensity at 650 and 710 nm, whereas complementary MALDI-MS studies are presented

  8. Bio-Aerosol Detection Using Mass Spectrometry: Public Health Applications

    SciTech Connect

    Ludvigson, Laura D.

    2004-01-01

    I recently spent a summer as an intern at the Lawrence Livermore National Laboratory. I worked on a project involving the real-time, reagentless, single cell detection of aerosolized pathogens using a novel mass spectrometry approach called Bio-Aerosol Mass Spectrometry (BAMS). Based upon preliminary results showing the differentiation capabilities of BAMS, I would like to explore the development and use of this novel detection system in the context of both environmental and clinical sample pathogen detection. I would also like to explore the broader public health applications that a system such as BAMS might have in terms of infectious disease prevention and control. In order to appreciate the potential of this instrument, I will demonstrate the need for better pathogen detection methods, and outline the instrumentation, data analysis and preliminary results that lead me toward a desire to explore this technology further. I will also discuss potential experiments for the future along with possible problems that may be encountered along the way.

  9. Application of mass spectrometric methods to analysis of xenobiotics in biological systems.

    PubMed

    Gross, M L

    1982-01-01

    Tetrachlorodibenzo-para-dioxin (TCDD) has been identified and quantitated at the parts-per-trillion level in three studies involving tissue. The first was an analysis of human milk from mothers in forest areas of the USA where herbicides containing 2,3,7,8-TCDD had been used. The second concerned US veterans of the Vietnam war who may have been exposed to 2,3,7,8-TCDD via contact with the defoliant, Agent Orange. The third was a controlled investigation of the fate of 2,3,7,8-TCDD in the tissue of an exposed rhesus monkey. Mass spectrometry has also been used to develop new methods for trace analysis. High-performance liquid chromatography coupled with gas chromatography/mass spectrometry, negative chemical ionization, mass spectrometry/mass spectrometry and Fourier transform mass spectrometry are described as examples.

  10. Differentiation of Aurantii Fructus Immaturus from Poniciri Trifoliatae Fructus Immaturus using flow-injection mass spectrometric (FIMS) metabolic fingerprinting method combined with chemometrics.

    PubMed

    Zhao, Yang; Chang, Yuan-Shiun; Chen, Pei

    2015-03-25

    A flow-injection mass spectrometric metabolic fingerprinting method in combination with chemometrics was used to differentiate Aurantii Fructus Immaturus from its counterfeit Poniciri Trifoliatae Fructus Immaturus. Flow-injection mass spectrometric (FIMS) fingerprints of 9 Aurantii Fructus Immaturus samples and 12 Poniciri Trifoliatae Fructus Immaturus samples were acquired and analyzed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The authentic herbs were differentiated from their counterfeits easily. Eight characteristic components which were responsible for the differences between the samples were tentatively identified. Furthermore, three out of the eight components, naringin, hesperidin, and neohesperidin, were quantified. The results are useful to help identify the authenticity of Aurantii Fructus Immaturus.

  11. Aerosol Composition in the Los Angeles Basin Studied by High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hayes, P. L.; Ortega, A. M.; Cubison, M.; Hu, W.; Toohey, D. W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S. L.; Rappenglueck, B.; Allan, J. D.; Taylor, J.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; De Gouw, J. A.; Massoli, P.; Zhang, X.; Weber, R.; Zhao, Y.; Cliff, S. S.; Wexler, A. S.; Isaacman, G. A.; Worton, D. R.; Kreisberg, N. M.; Hering, S. V.; Goldstein, A. H.; Jimenez, J. L.

    2011-12-01

    Atmospheric aerosols impact climate and health, but their sources and composition are poorly understood. To address this knowledge gap, a high-resolution aerosol mass spectrometer (AMS) and complementary instrumentation were deployed during the 2010 CalNex campaign to characterize aerosol composition in the Los Angeles (LA) area. Total mass concentrations as well as the species concentrations measured by the AMS compare well with most other instruments. Nitrate dominates in the mornings, but its concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentrations are strongly influenced by emission transport from the source-rich western basin. The average OA to enhanced CO ratio increases with photochemical age from 25 to 80 μg m-3 ppm-1, which indicates significant secondary OA (SOA) production and that a large majority of OA is secondary in aged air. The ratio values are similar to those from Mexico City as well as New England and the Mid-Atlantic States. Positive matrix factorization (PMF) is used to assess the concentrations of different OA components. The major OA classes are oxygenated OA (OOA, a surrogate for total SOA), and hydrocarbon-like OA (HOA, a surrogate for primary combustion OA). Several subclasses of OA are identified as well including diesel-influenced HOA (DI-HOA) and non-diesel HOA. DI-HOA exhibits low concentrations on Sundays consistent with the well-known weekday/weekend effect in LA. PMF analysis finds that OOA is 67% of the total OA concentration. A strong correlation between OOA and Ox (O3 + NO2) concentrations is observed with a slope of 0.15 that suggests the production of fresh SOA in Pasadena. Plotting the OA elemental ratios in a Van Krevelen diagram (H:C vs. O:C) yields a slope of -0.6, which is less steep than that observed in Riverside during the SOAR-2005 campaign. The difference in slopes may be attributed to the highly oxidized HOA present in Pasadena that is

  12. Hydrothermal carbonization of biomass residues: mass spectrometric characterization for ecological effects in the soil-plant system.

    PubMed

    Jandl, Gerald; Eckhardt, Kai-Uwe; Bargmann, Inge; Kücke, Martin; Greef, Jörg-Michael; Knicker, Heike; Leinweber, Peter

    2013-01-01

    Hydrochars, technically manufactured by hydrothermal carbonization (HTC) of biomass residues, are recently tested in high numbers for their suitability as feedstock for bioenergy production, the bioproduct industry, and as long-term carbon storage in soil, but ecological effects in the soil-plant system are not sufficiently known. Therefore, we investigated the influence of different biomass residues and process duration on the molecular composition of hydrochars, and how hydrochar addition to soils affected the germination of spring barley ( L.) seeds. Samples from biomass residues and the corresponding hydrochars were analyzed by pyrolysis-field ionization mass spectrometry (Py-FIMS) and gaseous emissions from the germination experiments with different soil-hydrochar mixtures by gas chromatography/mass spectrometry (GC/MS). The molecular-level characterization of various hydrochars by Py-FIMS clearly showed that the kind of biomass residue influenced the chemical composition of the corresponding hydrochars more strongly than the process duration. In addition to various detected possible toxic substances, two independent mass spectrometric methods (Py-FIMS and GC/MS) indicated long C-chain aliphatic compounds which are typically degraded to the C-unit ethylene that can evoke phytotoxic effects in high concentrations. This showed for the first time possible chemical compounds to explain toxic effects of hydrochars on plant growth. It is concluded that the HTC process did not result in a consistent product with defined chemical composition. Furthermore, possible toxic effects urgently need to be investigated for each individual hydrochar to assess effects on the soil organic matter composition and the soil biota before hydrochar applications as an amendment on agricultural soils.

  13. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  14. A novel mass spectrometric strategy "BEMAP" reveals Extensive O-linked protein glycosylation in Enterotoxigenic Escherichia coli.

    PubMed

    Boysen, Anders; Palmisano, Giuseppe; Krogh, Thøger Jensen; Duggin, Iain G; Larsen, Martin R; Møller-Jensen, Jakob

    2016-08-26

    The attachment of sugars to proteins via side-chain oxygen atoms (O-linked glycosylation) is seen in all three domains of life. However, a lack of widely-applicable analytical tools has restricted the study of this process, particularly in bacteria. In E. coli, only four O-linked glycoproteins have previously been characterized. Here we present a glycoproteomics technique, termed BEMAP, which is based on the beta-elimination of O-linked glycans followed by Michael-addition of a phosphonic acid derivative, and subsequent titanium dioxide enrichment. This strategy allows site-specific mass-spectrometric identification of proteins with O-linked glycan modifications in a complex biological sample. Using BEMAP we identified cell surface-associated and membrane vesicle glycoproteins from Enterotoxigenic E. coli (ETEC) and non-pathogenic E. coli K-12. We identified 618 glycosylated Serine and Threonine residues mapping to 140 proteins in ETEC, including several known virulence factors, and 34 in E. coli K-12. The two strains had 32 glycoproteins in common. Remarkably, the majority of the ETEC glycoproteins were conserved in both strains but nevertheless were only glycosylated in the pathogen. Therefore, bacterial O-linked glycosylation is much more extensive than previously thought, and is especially important to the pathogen.

  15. Molecular cloning, mass spectrometric identification, and nutritional evaluation of 10 coixins in adlay ( Coix lachryma-jobi L.).

    PubMed

    Lin, Li-Jen; Hsiao, Eric S L; Tseng, Hsen-Shong; Chung, Mei-Chu; Chua, Anna C N; Kuo, Ming-En; Tzen, Jason T C

    2009-11-25

    Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) is regarded as a nutritive food source as well as herbal medicine. The food nutrition is a consequence of its high protein content and superior amino acid composition. From ca. 200 expressed sequence tag (EST) sequences in maturing adlay grains, clones encoding precursor polypeptides of 10 seed storage proteins in the prolamin family, including 8 alpha-coixin isoforms, 1 delta-coixin, and 1 gamma-coixin, were identified. Full-length cDNA fragments encoding these 10 coixins were obtained by PCR cloning. Mass spectrometric analyses confirmed the presence of these 10 coixins in the extract of adlay grain. Calculated amino acid compositions indicate that all 10 coixins are rich in glutamine (>20% in alpha-coixin isoforms, 13.3% in delta-coixin, and 31.2% in gamma-coixin). The 8 alpha-coixin isoforms are low in methionine, cysteine, and lysine (on average, 0.8, 0.6, and 0.1%, respectively). However, the delta-coixin is a sulfur-rich protein (18.2% methionine and 9.1% cysteine), and the gamma-coixin is a nutritive protein composed of 2.0% methionine, 6.6% cysteine, 2.6% lysine, and 8.9% histidine. The company of delta-coixin and gamma-coixin with alpha-coixin isoforms enhances the nutritional value of alday grain for human consumption.

  16. Mass Spectrometric-Based Selected Reaction Monitoring of Protein Phosphorylation during Symbiotic Signaling in the Model Legume, Medicago truncatula

    PubMed Central

    Maeda, Junko; Barrett-Wilt, Gregory A.; Sussman, Michael R.

    2016-01-01

    Unlike the major cereal crops corn, rice, and wheat, leguminous plants such as soybean and alfalfa can meet their nitrogen requirement via endosymbiotic associations with soil bacteria. The establishment of this symbiosis is a complex process playing out over several weeks and is facilitated by the exchange of chemical signals between these partners from different kingdoms. Several plant components that are involved in this signaling pathway have been identified, but there is still a great deal of uncertainty regarding the early events in symbiotic signaling, i.e., within the first minutes and hours after the rhizobial signals (Nod factors) are perceived at the plant plasma membrane. The presence of several protein kinases in this pathway suggests a mechanism of signal transduction via posttranslational modification of proteins in which phosphate is added to the hydroxyl groups of serine, threonine and tyrosine amino acid side chains. To monitor the phosphorylation dynamics and complement our previous untargeted 'discovery' approach, we report here the results of experiments using a targeted mass spectrometric technique, Selected Reaction Monitoring (SRM) that enables the quantification of phosphorylation targets with great sensitivity and precision. Using this approach, we confirm a rapid change in the level of phosphorylation in 4 phosphosites of at least 4 plant phosphoproteins that have not been previously characterized. This detailed analysis reveals aspects of the symbiotic signaling mechanism in legumes that, in the long term, will inform efforts to engineer this nitrogen-fixing symbiosis in important non-legume crops such as rice, wheat and corn. PMID:27203723

  17. Mass Spectrometric Analysis of TRPM6 and TRPM7 Phosphorylation Reveals Regulatory Mechanisms of the Channel-Kinases

    PubMed Central

    Cai, Na; Bai, Zhiyong; Nanda, Vikas; Runnels, Loren W.

    2017-01-01

    TRPM7 and TRPM6 were the first identified bifunctional channels to contain their own kinase domains, but how these channel-kinases are regulated is poorly understood. Previous studies identified numerous phosphorylation sites on TRPM7, but very little is known about TRPM6 phosphorylation or sites on TRPM7 transphosphorylated by TRPM6. Our mass spectrometric analysis of homomeric and heteromeric TRPM7 and TRPM6 channels identified phosphorylation sites on both proteins, as well as several prominent sites on TRPM7 that are commonly modified through autophosphorylation and transphosphorylation by TRPM6. We conducted a series of amino acid substitution analyses and identified S1777, in TRPM7’s catalytic domain, and S1565, in TRPM7’s exchange domain that mediates kinase dimerization, as potential regulatory sites. The phosphomimetic S1777D substitution disrupted catalytic activity, most likely by causing an electrostatic perturbation at the active site. The S1565D phosphomimetic substitution also inactivated the kinase but did so without interfering with kinase dimerization. Molecular modeling indicates that phosphorylation of S1565 is predicted to structurally affect TRPM7’s functionally conserved N/D loop, which is thought to influence the access of substrate to the active site pocket. We propose that phosphorylation of S1565 within the exchange domain functions as a regulatory switch to control TRPM7 catalytic activity. PMID:28220887

  18. Discovery of Chromatin-Associated Proteins via Sequence-Specific Capture and Mass Spectrometric Protein Identification in Saccharomyces cerevisiae.

    PubMed

    Kennedy-Darling, Julia; Guillen-Ahlers, Hector; Shortreed, Michael R; Scalf, Mark; Frey, Brian L; Kendziorski, Christina; Olivier, Michael; Gasch, Audrey P; Smith, Lloyd M

    2014-08-01

    DNA-protein interactions play critical roles in the control of genome expression and other fundamental processes. An essential element in understanding how these systems function is to identify their molecular components. We present here a novel strategy, Hybridization Capture of Chromatin Associated Proteins for Proteomics (HyCCAPP), to identify proteins that are interacting with any given region of the genome. This technology identifies and quantifies the proteins that are specifically interacting with a genomic region of interest by sequence-specific hybridization capture of the target region from in vivo cross-linked chromatin, followed by mass spectrometric identification and quantification of associated proteins. We demonstrate the utility of HyCCAPP by identifying proteins associated with three multicopy and one single-copy loci in yeast. In each case, a locus-specific pattern of target-associated proteins was revealed. The binding of previously unknown proteins was confirmed by ChIP in 11 of 17 cases. The identification of many previously known proteins at each locus provides strong support for the ability of HyCCAPP to correctly identify DNA-associated proteins in a sequence-specific manner, while the discovery of previously unknown proteins provides new biological insights into transcriptional and regulatory processes at the target locus.

  19. iTRAQ-based profiling of grape berry exocarp proteins during ripening using a parallel mass spectrometric method.

    PubMed

    Martínez-Esteso, Maria José; Casado-Vela, Juan; Sellés-Marchart, Susana; Elortza, Felix; Pedreño, Maria Angeles; Bru-Martínez, Roque

    2011-03-01

    The 4-plex iTRAQ platform was utilized to analyze the protein profiles in four stages of grapevine berry skin ripening, from pre-veraison to fully ripening. Mass spectrometric data were acquired from three replicated analyses using a parallel acquisition method in an Orbitrap instrument by combining collision-induced dissociation (CID) and higher energy collision-induced dissociation (HCD) peptide ion fragmentations. As a result, the number of spectra suitable for peptide identification (either from CID or HCD) increased 5-fold in relation to those suitable for quantification (from HCD). Spectra were searched against an NCBInr protein database subset containing all the Vitis sequences, including those derived from whole genome sequencing. In general, 695 unique proteins were identified with more than one single peptide, and 513 of them were quantified. The sequence annotation and GO term enrichment analysis assisted by the automatic annotation tool Blast2GO permitted a pathway analysis which resulted in finding that biological processes and metabolic pathways de-regulated throughout ripening. A detailed analysis of the function-related proteins profiles helped discover a set of proteins of known Vitis gene origin as the potential candidates to play key roles in grapevine berry quality, growth regulation and disease resistance.

  20. Mass spectrometric gas composition measurements associated with jet interaction tests in a high-enthalpy wind tunnel

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Brown, K. G.; Wood, G. M., Jr.; Puster, R. L.; Paulin, P. A.; Fishel, C. E.; Ellerbe, D. A.

    1986-01-01

    Knowledge of test gas composition is important in wind-tunnel experiments measuring aerothermodynamic interactions. This paper describes measurements made by sampling the top of the test section during runs of the Langley 7-Inch High-Temperature Tunnel. The tests were conducted to determine the mixing of gas injected from a flat-plate model into a combustion-heated hypervelocity test stream and to monitor the CO2 produced in the combustion. The Mass Spectrometric (MS) measurements yield the mole fraction of N2 or He and CO2 reaching the sample inlets. The data obtained for several tunnel run conditions are related to the pressures measured in the tunnel test section and at the MS ionizer inlet. The apparent distributions of injected gas species and tunnel gas (CO2) are discussed relative to the sampling techniques. The measurements provided significant real-time data for the distribution of injected gases in the test section. The jet N2 diffused readily from the test stream, but the jet He was mostly entrained. The amounts of CO2 and Ar diffusing upward in the test section for several run conditions indicated the variability of the combustion-gas test-stream composition.

  1. Gas chromatography-high-resolution mass spectrometric method for determination of methamphetamine and its major metabolite amphetamine in human hair.

    PubMed

    Kim, Jin Young; Suh, Sung Ill; In, Moon Kyo; Chung, Bong Chul

    2005-01-01

    Gas chromatography-high-resolution mass spectrometric (GC-HRMS) method is presented for the qualitative and quantitative analysis of methamphetamine (MA) and its major metabolite, amphetamine (AMP), in human hair. The method procedure involves decontamination of hair with distilled water and acetone, acidic hydrolysis and extraction in the presence of the internal standard, and GC-HRMS selective ion monitoring (SIM) analysis. The limits of detection (LOD) were 9 pg/mg for MA and 21 pg/mg for AMP using a 30-mg hair sample, and the SIM responses were linear with coefficients of correlation ranged from 0.9998 to 0.9999. The recoveries were found to be 91.1-92.3%. By using HRMS (resolution of 5000), detection sensitivity is improved because of the elimination of the biological background, and the LODs for MA and AMP were 2.4-4.4 times lower than those of low-resolution MS. The GC-HRMS method was successfully applied to the analysis of cosmetically treated hair, which is difficult to analyze with the conventional method.

  2. Combining Mass Spectrometric Metabolic Profiling with Genomic Analysis: A Powerful Approach for Discovering Natural Products from Cyanobacteria.

    PubMed

    Kleigrewe, Karin; Almaliti, Jehad; Tian, Isaac Yuheng; Kinnel, Robin B; Korobeynikov, Anton; Monroe, Emily A; Duggan, Brendan M; Di Marzo, Vincenzo; Sherman, David H; Dorrestein, Pieter C; Gerwick, Lena; Gerwick, William H

    2015-07-24

    An innovative approach was developed for the discovery of new natural products by combining mass spectrometric metabolic profiling with genomic analysis and resulted in the discovery of the columbamides, a new class of di- and trichlorinated acyl amides with cannabinomimetic activity. Three species of cultured marine cyanobacteria, Moorea producens 3L, Moorea producens JHB, and Moorea bouillonii PNG, were subjected to genome sequencing and analysis for their recognizable biosynthetic pathways, and this information was then compared with their respective metabolomes as detected by MS profiling. By genome analysis, a presumed regulatory domain was identified upstream of several previously described biosynthetic gene clusters in two of these cyanobacteria, M. producens 3L and M. producens JHB. A similar regulatory domain was identified in the M. bouillonii PNG genome, and a corresponding downstream biosynthetic gene cluster was located and carefully analyzed. Subsequently, MS-based molecular networking identified a series of candidate products, and these were isolated and their structures rigorously established. On the basis of their distinctive acyl amide structure, the most prevalent metabolite was evaluated for cannabinomimetic properties and found to be moderate affinity ligands for CB1.

  3. Determination of phthalate esters in cosmetics by gas chromatography with flame ionization detection and mass spectrometric detection.

    PubMed

    Chen, Huiming; Wang, Chao; Wang, Xing; Hao, Nan; Liu, Juan

    2005-08-01

    A gas chromatography coupled with flame ionization detection (GC-FID) and mass spectrometric detection (MSD) method was developed to determine the six kinds of phthalate esters [dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DOP)] in cosmetics (solid, cream and liquid cosmetics). The cosmetics were extracted with methanol by ultrasonic and then separated with high-speed centrifugation. The upper clear layer was dried and filtered through a 0.45 mum pore diameter filter. The filtrate was injected into GC-FID/GC-MS for detection. GC-FID chromatogram was applied for qualitative analysis, external standard method was used for quantitative analysis. Confirmation of phthalate presence was undertaken by GC-EI-MS. The recovery range of all phthalates were between 92.0 and 110.0% with relative standard deviations between 1.95 and 5.92%. The low detection limits of the method were: 0.1 ng for DMP, DEP, DBP and BBP, 0.5 ng for DEHP and DOP. The method had advantages of high precision and sensitivity, simplicity of pretreatment. The method can be used to test the six kinds of phthalate esters in cosmetics.

  4. Gas chromatographic-mass spectrometric determination of brain levels of alpha-cholest-8-en-3beta-ol (lathosterol).

    PubMed

    Luzón-Toro, Berta; Zafra-Gómez, Alberto; Ballesteros, Oscar

    2007-05-01

    A gas chromatographic-mass spectrometric (GC-MS) method is proposed for the detection and quantification of lathosterol in rabbit brain. This compound is one of the most important precursors of the cholesterol synthesis. The interest in brain cholesterol metabolism is growing nowadays since it was described to play an important role in some neurodegenerative disorders such as Alzheimer's disease and Multiple Sclerosis. The analytical methodology proposed involves a liquid-liquid extraction procedure (LLE) followed by a silylation step previous to the GC-MS analysis. The chromatographic separation was performed by using a low bleed HP5-MS fused silica capillary column. A clean up is not necessary when using single-ion monitoring (SIM) mode. The molecular ion appears at 458 m/z; being as well the base peak. Alpha-naphtol was used as an internal standard. The detection limit obtained was 0.09 microg mL(-1). The method was applied to the determination of brain lathosterol levels in rabbits fed with different types of diets (control and atherogenic, supplemented or not with natural polyphenolic antioxidants). The quantification of the compound in samples showed a reduction, after 1 month, of this precursor of cholesterol synthesis in groups fed with antioxidant supplemented diets.

  5. Selective isolation of hydrophobin SC3 by solid-phase extraction with polytetrafluoroethylene microparticles and subsequent mass spectrometric analysis.

    PubMed

    Kupčík, Rudolf; Zelená, Miroslava; Řehulka, Pavel; Bílková, Zuzana; Česlová, Lenka

    2016-02-01

    Hydrophobins are small proteins that play a role in a number of processes during the filamentous fungi growth and development. These proteins are characterized by the self-assembly of their molecules into an amphipathic membrane at hydrophilic-hydrophobic interfaces. Isolation and purification of hydrophobins generally present a challenge in their analysis. Hydrophobin SC3 from Schizophyllum commune was selected as a representative of class I hydrophobins in this work. A novel procedure for selective and effective isolation of hydrophobin SC3 based on solid-phase extraction with polytetrafluoroethylene microparticles loaded in a small self-made microcolumn is reported. The tailored binding of hydrophobins to polytetrafluoroethylene followed by harsh elution conditions resulted in a highly specific isolation of hydrophobin SC3 from the model mixture of ten proteins. The presented isolation protocol can have a positive impact on the analysis and utilization of these proteins including all class I hydrophobins. Hydrophobin SC3 was further subjected to reduction of its highly stable disulfide bonds and to chymotryptic digestion followed by mass spectrometric analysis. The isolation and digestion protocols presented in this work make the analysis of these highly hydrophobic and compact proteins possible.

  6. A molecular beam mass spectrometric study of the formation and photolysis of C(lc)lO dimer

    NASA Technical Reports Server (NTRS)

    Greene, Frank T.; Robaugh, David A.

    1992-01-01

    A study of the chlorine oxides present at temperatures and pressures typical of the Antarctic stratosphere was carried out. A series of low temperature flow reactors was constructed and used in conjunction with molecular beam mass spectrometric techniques to identify species and characterize their kinetic behavior at temperatures of -20 to -70 C and pressures of from 30 to 130 Torr. It was found that the gas phase chlorine-oxygen system was quite complex at low temperatures. ClO dimer was identified and found to be thermodynamically very stable under stratospheric conditions. It was also found that any system which contained ClO also contained a larger oxide. The oxide was identified as Cl2O3. A survey of possible higher oxides, which have been postulated as possible chlorine sinks in the stratosphere, was also carried out. The rate of formation of ClO dimer was measured as a function of temperature and pressure. Measurements were made of both the decay of ClO and the formation of the dimer. By comparing these rates it was determined that virtually all of the ClO was converted to the dimer under stratospheric conditions, and that the other ClO reactions were not important under these conditions.

  7. Abortion after deliberate Arthrotec® addition to food. Mass spectrometric detection of diclofenac, misoprostol acid, and their urinary metabolites.

    PubMed

    Watzer, Bernhard; Lusthof, Klaas J; Schweer, Horst

    2015-07-01

    Arthrotec(®) (AT) is a combination of diclofenac, a nonsteroidal anti-inflammatory drug (NSAID), and misoprostol (MP), a synthetic analogue of prostaglandin E1 (PGE1). MP is a lipophilic methyl ester prodrug. It is readily metabolized to the biologically active misoprostol acid (MPA). During the last few years, medical studies exhibited MP to be an excellent abortive. In this paper, we describe a rare criminal case of MP abortion, initiated by the expectant father. After the abortion, samples of vomit and urine were collected. Systemic exposure to MP is difficult to prove, because both MP and the active metabolite MPA are hardly excreted in urine. Therefore, in addition to routine toxicological analysis, we used slightly modified, well-established liquid and gas chromatographic/tandem mass spectrometric (LC/MS/MS and GC/MS/MS) methods, for the direct and the indirect detection of MPA and its metabolites. In this case, we were able to demonstrate the presence of the major MP metabolites 2,3-dinor-MPA and 2,3,4,5-tetranor-MPA in the urine of the victim. We also detected paracetamol, 3-methoxyparacetamol and diclofenac-glucuronide in the urine. In the vomit of the victim, we detected diclofenac and MPA. These results, combined with the criminal investigations, showed that the accused had mixed MP into the food of his pregnant girlfriend. Finally, these investigations contributed to a confession of the accused.

  8. Peptide code-on-a-microplate for protease activity analysis via MALDI-TOF mass spectrometric quantitation.

    PubMed

    Hu, Junjie; Liu, Fei; Ju, Huangxian

    2015-04-21

    A peptide-encoded microplate was proposed for MALDI-TOF mass spectrometric (MS) analysis of protease activity. The peptide codes were designed to contain a coding region and the substrate of protease for enzymatic cleavage, respectively, and an internal standard method was proposed for the MS quantitation of the cleavage products of these peptide codes. Upon the cleavage reaction in the presence of target proteases, the coding regions were released from the microplate, which were directly quantitated by using corresponding peptides with one-amino acid difference as the internal standards. The coding region could be used as the unique "Protease ID" for the identification of corresponding protease, and the amount of the cleavage product was used for protease activity analysis. Using trypsin and chymotrypsin as the model proteases to verify the multiplex protease assay, the designed "Trypsin ID" and "Chymotrypsin ID" occurred at m/z 761.6 and 711.6. The logarithm value of the intensity ratio of "Protease ID" to internal standard was proportional to trypsin and chymotrypsin concentration in a range from 5.0 to 500 and 10 to 500 nM, respectively. The detection limits for trypsin and chymotrypsin were 2.3 and 5.2 nM, respectively. The peptide-encoded microplate showed good selectivity. This proposed method provided a powerful tool for convenient identification and activity analysis of multiplex proteases.

  9. Mass Spectrometric Analysis of TRPM6 and TRPM7 Phosphorylation Reveals Regulatory Mechanisms of the Channel-Kinases.

    PubMed

    Cai, Na; Bai, Zhiyong; Nanda, Vikas; Runnels, Loren W

    2017-02-21

    TRPM7 and TRPM6 were the first identified bifunctional channels to contain their own kinase domains, but how these channel-kinases are regulated is poorly understood. Previous studies identified numerous phosphorylation sites on TRPM7, but very little is known about TRPM6 phosphorylation or sites on TRPM7 transphosphorylated by TRPM6. Our mass spectrometric analysis of homomeric and heteromeric TRPM7 and TRPM6 channels identified phosphorylation sites on both proteins, as well as several prominent sites on TRPM7 that are commonly modified through autophosphorylation and transphosphorylation by TRPM6. We conducted a series of amino acid substitution analyses and identified S1777, in TRPM7's catalytic domain, and S1565, in TRPM7's exchange domain that mediates kinase dimerization, as potential regulatory sites. The phosphomimetic S1777D substitution disrupted catalytic activity, most likely by causing an electrostatic perturbation at the active site. The S1565D phosphomimetic substitution also inactivated the kinase but did so without interfering with kinase dimerization. Molecular modeling indicates that phosphorylation of S1565 is predicted to structurally affect TRPM7's functionally conserved N/D loop, which is thought to influence the access of substrate to the active site pocket. We propose that phosphorylation of S1565 within the exchange domain functions as a regulatory switch to control TRPM7 catalytic activity.

  10. A novel mass spectrometric strategy “BEMAP” reveals Extensive O-linked protein glycosylation in Enterotoxigenic Escherichia coli

    PubMed Central

    Boysen, Anders; Palmisano, Giuseppe; Krogh, Thøger Jensen; Duggin, Iain G.; Larsen, Martin R.; Møller-Jensen, Jakob

    2016-01-01

    The attachment of sugars to proteins via side-chain oxygen atoms (O-linked glycosylation) is seen in all three domains of life. However, a lack of widely-applicable analytical tools has restricted the study of this process, particularly in bacteria. In E. coli, only four O-linked glycoproteins have previously been characterized. Here we present a glycoproteomics technique, termed BEMAP, which is based on the beta-elimination of O-linked glycans followed by Michael-addition of a phosphonic acid derivative, and subsequent titanium dioxide enrichment. This strategy allows site-specific mass-spectrometric identification of proteins with O-linked glycan modifications in a complex biological sample. Using BEMAP we identified cell surface-associated and membrane vesicle glycoproteins from Enterotoxigenic E. coli (ETEC) and non-pathogenic E. coli K-12. We identified 618 glycosylated Serine and Threonine residues mapping to 140 proteins in ETEC, including several known virulence factors, and 34 in E. coli K-12. The two strains had 32 glycoproteins in common. Remarkably, the majority of the ETEC glycoproteins were conserved in both strains but nevertheless were only glycosylated in the pathogen. Therefore, bacterial O-linked glycosylation is much more extensive than previously thought, and is especially important to the pathogen. PMID:27562176

  11. Comprehensive ultra-performance liquid chromatographic separation and mass spectrometric analysis of eicosanoid metabolites in human samples.

    PubMed

    Wang, Yan; Armando, Aaron M; Quehenberger, Oswald; Yan, Chao; Dennis, Edward A

    2014-09-12

    Over the past decade, the number of known eicosanoids has expanded immensely and we have now developed an ultra-performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometric (UPLC-QTRAP/MS/MS) method to monitor and quantify numerous eicosanoids. The UPLC-QTRAP/MS/MS approach utilizes scheduled multiple reaction monitoring (MRM) to optimize sensitivity, number of metabolites that can be analyzed and the time requirement of the analysis. A total of 184 eicosanoids including 26 deuterated internal standards can be separated and monitored in a single 5min UPLC run. To demonstrate a practical application, human plasma samples were analyzed following solid-phase extraction (SPE) and the recovery rate and matrix effects were determined for the 26 deuterated internal standards added to the plasma. The method was validated and shown to be sensitive with the limit of quantitation at pg levels for most compounds, accurate with recovery rates of 70-120%, and precise with a CV<30 for all compounds. Also, the method showed a linear response over a range spanning several orders of magnitude. In a QC human plasma sample, we identified and rigorously quantified over 120 eicosanoids.

  12. Electrospray ionization Fourier transform mass spectrometric analysis of intact bikunin glycosaminoglycan from normal human plasma.

    PubMed

    Laremore, Tatiana N; Leach, Franklin E; Amster, I Jonathan; Linhardt, Robert J

    2011-08-15

    A mixture of glycosaminoglycan (GAG) chains from a plasma proteoglycan bikunin was fractionated using native, continuous-elution polyacrylamide gel electrophoresis, and the resulting fractions were analyzed by electrospray ionization Fourier transform mass spectrometry (ESI FTMS). Molecular mass analysis of the intact GAG afforded information about the length and composition of GAG chains in the mixture. Ambiguity in the interpretation of the intact GAG mass spectra was eliminated by conducting an additional experiment in which the GAG chains of known molecular mass were treated with a GAG-degrading enzyme, chondroitinase ABC, and the digestion products were analyzed by ESI FTMS. The plasma bikunin GAG chains consisted predominantly of odd number of saccharides, although few chains consisting of even number of saccharides were also detected. Majority of the analyzed chains were tetrasulfated or pentasulfated and comprised by 29 to 41 monosaccharides.

  13. Production of deuterated lutein by Chlorella protothecoides and its detection by mass spectrometric methods.

    PubMed

    Bhosale, Prakash; Serban, Bogdan; Bernstein, Paul S

    2006-09-01

    Chlorella protothecoides, a lutein-producing microalga, was grown aerobically in a mineral medium prepared with 70% (v/v) deuterated water. HPLC/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) analysis revealed approximately 58% replacement of hydrogen by deuterium atoms as indicated by the molecular mass cluster at around m/z 599. The rapidly growing microalga had much higher levels (58%) of deuterium substitution relative to previously reported (9-15%) natural sources of lutein.

  14. Mass Spectrometric Measurements of the Concentrations of Gaseous Species in Reactive Flow Systems.

    DTIC Science & Technology

    1982-04-01

    concentrations of gaseous species in the ramjet combustor flow field under simulated combustion conditions. The goal of this effort was to study fuel-air... field patterns, all of which affect the operation of the mass spectrometer, a continously operating built-in calibration system must be utilized in order...sampling probe was first allowed to traverse the combustor flow field , into which only pure air had been injected. The mass spectrometer system was

  15. Mass Spectrometric Determination of Chemical Warfare Agents in Indoor Sample Media Typically Collected During Forensic Investigations

    DTIC Science & Technology

    2005-10-01

    la lutte contre le terrorisme. On s’attend A ce que continue la mise au point et l’application de la spectrom~trie de masse en tandem aux...terrorist use of weapons of mass destruction was the establishment of the Chemical, biological , radiological and nuclear Research and Technology Initiative...CRTI). This research-oriented organization originally formed three clusters to deal with the challenges associated with each of chemical, biological

  16. Role of the sample supports in the LDI mass spectrometric studies of silver clusters

    NASA Astrophysics Data System (ADS)

    Smolira, Anna

    2012-12-01

    One of the basic parameters of the LDI TOF MS (laser desorption ionization time of flight mass spectrometry) method is its sensitivity. It depends on many factors such as the proper sample preparation. Within the sample preparation various steps are taken to achieve the greatest sensitivity of the LDI method. One of them is the application of so-called sample supports on the stainless steel sample holder surface, on which the sample is loaded. The aim of this study was to examine the influence of sample supports selected by the author on the outcome of the experiment. In this respect, silver benzoate was studied. The apparatus used was a linear time of flight mass spectrometer and the method of ionization was LD (laser desorption). Mass spectra obtained for the sample support materials (glass, mica, floppy disc foil, copper, aluminium foil) were compared to those obtained with the stainless steel. All of these were recorded under identical experimental conditions. Mass spectra were characterized in terms of mass peaks registered. It was noted that the processes of silver clustering for each sample support and the stainless steel ran with different intensity. The largest registered ion cluster Agn was the biggest for floppy disc foil (n = 92), the smallest for copper (n = 59). The FWHM parameter in the case of Ag+ and Ag- ion mass peaks was the smallest for stainless steel. Metallic sample supports (copper, aluminum foil) appeared to be advantageous for the studies of negative ion mass spectra - negative ion current corresponding to particular ion mass peaks was then more intensive than positive ion current. The mica was the exception.

  17. ModelE2-TOMAS development and evaluation using aerosol optical depths, mass and number concentrations

    NASA Astrophysics Data System (ADS)

    Lee, Y. H.; Adams, P. J.; Shindell, D. T.

    2014-09-01

    The TwO-Moment Aerosol Sectional microphysics model (TOMAS) has been integrated into the state-of-the-art general circulation model, GISS ModelE2. TOMAS has the flexibility to select a size resolution as well as the lower size cutoff. A computationally efficient version of TOMAS is used here, which has 15 size bins covering 3 nm to 10 μm aerosol dry diameter. For each bin, it simulates the total aerosol number concentration and mass concentrations of sulphate, pure elementary carbon (hydrophobic), mixed elemental carbon (hydrophilic), hydrophobic organic matter, hydrophilic organic matter, sea salt, mineral dust, ammonium, and aerosol-associated water. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the TOMAS model is compared to the default aerosol model in ModelE2, which is a bulk aerosol model. Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement with observations of sulphur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as the bulk aerosol model) cannot capture the observed vertical distribution of sulphur dioxide over the Pacific Ocean possibly due to overly strong convective transport. The TOMAS model successfully captures observed aerosol number concentrations and cloud condensation nuclei concentrations. Anthropogenic aerosol burdens in the bulk aerosol model running in the same host model as TOMAS (ModelE2) differ by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. Larger differences are found for naturally

  18. Liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometric characterization of protein kinase C phosphorylation.

    PubMed

    Chalmers, Michael J; Quinn, John P; Blakney, Greg T; Emmett, Mark R; Mischak, Harold; Gaskell, Simon J; Marshall, Alan G

    2003-01-01

    A vented column, capillary liquid chromatography (LC) microelectrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR (9.4 T)) mass spectrometry (MS) approach to phosphopeptide identification is described. A dual-ESI source capable of rapid (approximately 200 ms) switching between two independently controlled ESI emitters was constructed. The dual-ESI source, combined with external ion accumulation in a linear octopole ion trap, allowed for internal calibration of every mass spectrum during LC. LC ESI FT-ICR positive-ion MS of protein kinase C (PKC) revealed four previously unidentified phosphorylated peptides (one within PKC(alpha), one within PKC(delta), and two within PKC(zeta)). Internal calibration improved the mass accuracy for LC MS spectra from an absolute mean (47 peptide ions) of 11.5 ppm to 1.5 ppm. Five additional (out of eight known) activating sites of PKC phosphorylation, not detected in positive-ion experiments, were observed by subsequent negative-ion direct infusion nanoelectrospray. Extension of the method to enable infrared multiphoton dissociation of all ions in the ICR cell prior to every other mass measurement revealed the diagnostic neutral loss of H3PO4 from phosphorylated peptide ions. The combination of accurate-mass MS and MS/MS offers a powerful new tool for identifying the presence and site(s) of phosphorylation in peptides, without the need for additional wet chemical derivatization.

  19. Mass spectrometric signatures of the blood plasma metabolome for disease diagnostics.

    PubMed

    Lokhov, Petr G; Balashova, Elena E; Voskresenskaya, Anna A; Trifonova, Oxana P; Maslov, Dmitry L; Archakov, Alexander I

    2016-01-01

    In metabolomics, a large number of small molecules can be detected in a single run. However, metabolomic data do not include the absolute concentrations of each metabolite. Generally, mass spectrometry analyses provide metabolite concentrations that are derived from mass peak intensities, and the peak intensities are strictly dependent on the type of mass spectrometer used, as well as the technical characteristics, options and protocols applied. To convert mass peak intensities to actual concentrations, calibration curves have to be generated for each metabolite, and this represents a significant challenge depending on the number of metabolites that are detected and involved in metabolome-based diagnostics. To overcome this limitation, and to facilitate the development of diagnostic tests based on metabolomics, mass peak intensities may be expressed in quintiles. The present study demonstrates the advantage of this approach. The examples of diagnostic signatures, which were designed in accordance to this approach, are provided for lung and prostate cancer (leading causes of mortality due to cancer in developed countries) and impaired glucose tolerance (which precedes type 2 diabetes, the most common endocrinology disease worldwide).

  20. VUV photon-induced ionization/dissociation of antipyrine and propyphenazone: mass spectrometric and theoretical insights.

    PubMed

    Deng, Liulin; Zhang, Lidong; Guo, Huijun; Jia, Liangyuan; Pan, Yang; Yin, Hao; Qi, Fei

    2010-07-01

    Two analgesic and anti-inflammatory drugs, antipyrine and propyphenazone, were investigated with infrared laser desorption/tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (IR LD/VUV PIMS) and theoretical calculations. Mass spectra of the two drugs were measured at various photon energies. Fragment ions were gradually produced as photon energy increases. The structural assignment of the dominant fragment ions was supported by the results from a commercial electron impact time-of-flight mass spectrometer (EI-TOF MS). Primary fragmentation pathways were established from experimental observations combining with theoretical calculations. Methyl radical elimination is a common fragmentation pathway for two analytes. However, for propyphenazone cation, isopropyl group elimination to form antipyrine cation is another competitive pathway.

  1. Fingerprinting Breast Cancer vs. Normal Mammary Cells by Mass Spectrometric Analysis of Volatiles

    PubMed Central

    He, Jingjing; Sinues, Pablo Martinez-Lozano; Hollmén, Maija; Li, Xue; Detmar, Michael; Zenobi, Renato

    2014-01-01

    There is increasing interest in the development of noninvasive diagnostic methods for early cancer detection, to improve the survival rate and quality of life of cancer patients. Identification of volatile metabolic compounds may provide an approach for noninvasive early diagnosis of malignant diseases. Here we analyzed the volatile metabolic signature of human breast cancer cell lines versus normal human mammary cells. Volatile compounds in the headspace of conditioned culture medium were directly fingerprinted by secondary electrospray ionization-mass spectrometry. The mass spectra were subsequently treated statistically to identify discriminating features between normal vs. cancerous cell types. We were able to classify different samples by using feature selection followed by principal component analysis (PCA). Additionally, high-resolution mass spectrometry allowed us to propose their chemical structures for some of the most discriminating molecules. We conclude that cancerous cells can release a characteristic odor whose constituents may be used as disease markers. PMID:24903350

  2. Development of mass spectrometric techniques applicable to the search for organic matter in the lunar crust

    NASA Technical Reports Server (NTRS)

    Biemann, K.

    1973-01-01

    Data processing techniques were developed to measure with high precision and sensitivity the line spectra produced by a high resolution mass spectrometer. The most important aspect of this phase was the interfacing of a modified precision microphotometer-comparator with a computer and the improvement of existing software to serve the special needs of the investigation of lunar samples. In addition, a gas-chromatograph mass spectrometer system was interfaced with the same computer to allow continuous recording of mass spectra on a gas chromatographic effluent and efficient evaluation of the resulting data. These techniques were then used to detect and identify organic compounds present in the samples returned by the Apollo 11 and 12 missions.

  3. Fingerprinting Breast Cancer vs. Normal Mammary Cells by Mass Spectrometric Analysis of Volatiles

    NASA Astrophysics Data System (ADS)

    He, Jingjing; Sinues, Pablo Martinez-Lozano; Hollmén, Maija; Li, Xue; Detmar, Michael; Zenobi, Renato

    2014-06-01

    There is increasing interest in the development of noninvasive diagnostic methods for early cancer detection, to improve the survival rate and quality of life of cancer patients. Identification of volatile metabolic compounds may provide an approach for noninvasive early diagnosis of malignant diseases. Here we analyzed the volatile metabolic signature of human breast cancer cell lines versus normal human mammary cells. Volatile compounds in the headspace of conditioned culture medium were directly fingerprinted by secondary electrospray ionization-mass spectrometry. The mass spectra were subsequently treated statistically to identify discriminating features between normal vs. cancerous cell types. We were able to classify different samples by using feature selection followed by principal component analysis (PCA). Additionally, high-resolution mass spectrometry allowed us to propose their chemical structures for some of the most discriminating molecules. We conclude that cancerous cells can release a characteristic odor whose constituents may be used as disease markers.

  4. Vacuum-Ultraviolet Photoionization and Mass Spectrometric Characterization of Lignin Monomers Coniferyl and Sinapyl Alcohols

    SciTech Connect

    Takahashi, Lynelle K.; Zhou, Jia; Kostko, Oleg; Golan, Amir; Leone, Stephen R.; Ahmed, Musahid

    2011-02-09

    The fragmentation mechanisms of monolignols under various energetic processes are studied with jet-cooled thermal desorption molecular beam (TDMB) mass spectrometry (MS), 25 keV Bi3+ secondary ion MS (SIMS), synchrotron vacuum-ultraviolet secondary neutral MS (VUV-SNMS) and theoretical methods. Experimental and calculated appearance energies of fragments observed in TDMB MS indicate that the coniferyl alcohol photoionization mass spectra contain the molecular parent and several dissociative photoionization products. Similar results obtained for sinapyl alcohol are also discussed briefly. Ionization energies of 7.60 eV ? 0.05 eV for coniferyl alcohol and<7.4 eV for both sinapyl and dihydrosinapyl alcohols are determined. The positive ion SIMS spectrum of coniferyl alcohol shares few characteristic peaks (m/z = 137 and 151) with the TDMB mass spectra, shows extensive fragmentation, and does not exhibit clear molecular parent signals. VUV-SNMS spectra, on the other hand, are dominated by the parent ion and main fragments also present in the TDMB spectra. Molecular fragmentation in VUV-SNMS spectra can be reduced by increasing the extraction delay time. Some features resembling the SIMS spectra are also observed in the desorbed neutral products. The monolignol VUV-SNMS peaks shared with the TDMB mass spectra suggest that dissociative photoionization of ion-sputtered neutral molecules predominate in the VUV-SNMS mass spectra, despite the extra internal energy imparted in the initial ion impact. The potential applications of these results to imaging mass spectrometry of bio-molecules are discussed.

  5. A comparative mass spectrometric study of fatty acids and metals in some seed extracts.

    PubMed

    Suvar, Sonia Niculina; Bleiziffer, R; Podea, P; Iordache, A; Voica, C; Zgavarogea, R; Culea, M

    2016-01-01

    A major cause of cardiovascular diseases and cancer is diet content, so the optimization of micronutrients in food is very important. Omega-3 fatty acids supplementation for patients had beneficial effects on subjective global assessment score and metabolic profiles. Fatty acids content and the metal ions in different seeds (e.g. linseed, poppy, grape, hemp, nuts, pumpkin, sesame, watermelon, chia) recommended as food supplements, purchased on the Romanian market, were compared. Gas chromatography coupled to mass spectrometry (GC-MS) was used as an excellent technique for fatty acids identification and quantitation, and inductively coupled plasma mass spectrometer (ICP-MS) for analytical measurements of metals.

  6. Electrospray ionization mass spectrometric studies of some imidazole amidoximes and nitrolic acids and their esters.

    PubMed

    Oresmaa, Larisa; Aulaskari, Paula; Vainiotalo, Pirjo

    2006-01-01

    The fragmentations of the [M+H]+ ions of imidazole amidoximes, and nitrolic acids and their esters, were studied by collision-induced dissociation experiments and by determining the accurate masses of the product ions on an electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer. The fragmentation pathways of the amidoximes varied with the substituent in the imidazole ring at position 1N, allowing two regioisomers to be distinguished. Nitrolic acids decompose in solution to nitrile oxides, and the studied nitrolic acid behaved in the same way in the gas phase. The esters decompose similarly to their parent compounds.

  7. Mass spectrometric identification and quantification of 5-methoxytryptophol in quail retina

    SciTech Connect

    Tsang, C.W.; Chan, S.F.; Lee, P.P.; Pang, S.F. )

    1989-12-29

    The occurrence of 5-methoxytryptophol (5-MTL) in the quail retina was investigated by capillary column gas chromatography/mass spectrometry/selected ion monitoring using a deuterated internal standard. Based on ion intensity ratios in the mass spectra of pentafluoropropionyl and heptafluorobutyryl derivatives of 5-MTL and deuterated 5-MTL, 5-MTL was unequivocally identified in the quail retina. Similar to the circadian rhythm of retinal melatonin, retinal 5-MTL also exhibited a diurnal variation with high levels at mid-dark. However, no significant correlation between the diurnal levels of 5-MTL and melatonin was observed in the quail retina at mid-light or mid-dark.

  8. Focused analyte spray emission apparatus and process for mass spectrometric analysis

    DOEpatents

    Roach, Patrick J [Kennewick, WA; Laskin, Julia [Richland, WA; Laskin, Alexander [Richland, WA

    2012-01-17

    An apparatus and process are disclosed that deliver an analyte deposited on a substrate to a mass spectrometer that provides for trace analysis of complex organic analytes. Analytes are probed using a small droplet of solvent that is formed at the junction between two capillaries. A supply capillary maintains the droplet of solvent on the substrate; a collection capillary collects analyte desorbed from the surface and emits analyte ions as a focused spray to the inlet of a mass spectrometer for analysis. The invention enables efficient separation of desorption and ionization events, providing enhanced control over transport and ionization of the analyte.

  9. ION COMPOSITION ELUCIDATION (ICE): A HIGH RESOLUTION MASS SPECTROMETRIC TECHNIQUE FOR IDENTIFYING COMPOUNDS IN COMPLEX MIXTURES

    EPA Science Inventory

    When tentatively identifying compounds in complex mixtures using mass spectral libraries, multiple matches or no plausible matches due to a high level of chemical noise or interferences can occur. Worse yet, most analytes are not in the libraries. In each case, Ion Composition El...

  10. Mass Spectrometric Identification of the Arginine and Lysine deficient Proline Rich Glutamine Rich Wheat Storage Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tandem mass spectrometry (MS/MS) of enzymatic digest has made possible identification of a wide variety of proteins and complex samples prepared by such techniques as RP-HPLC or 2-D gel electrophoresis. Success requires peptide fragmentation to be indicative of the peptide amino acid sequence. The f...

  11. DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

  12. Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. II.

    PubMed

    Takhistov, Viatcheslav V; Khoroshko, Larisa O; Viktorovskii, Igor V; Lahtiperä, Mirja; Paasivirta, Jaakko

    2004-01-01

    Nine polysulfides, previously unknown as environmental organic pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to low- and high-resolution mass spectrometers. The structure of the polysulfides was elucidated by determination of isotopic composition of abundant molecular and fragment ions by high-resolution mass spectrometry (HRMS), the interpretation of ion structures in low-resolution mass spectra (LMRS) using the thermochemical approach, the application of fragmentation rules and performing the ICLU simulation of abundance of ions in isotope clusters. Seven compounds were known in literature, but mass spectra were reported for only two of them, both recorded from mixture. Struture evaluation was successful for other substances, but not for the substance(s) in first eluting GC peak, where HRMS date were not obtained. Suggested structures of the cyclic compounds were (in the order of GC retention) 3,4-dithiacyclohexene, 1,2,3-trithiacyclohexane, 3,4,5- trithiacyclohexene, 1,2,4-trithiacyclohexane, cyclopropyl hydrodisulfide, 1,2-dithiole-3-thione and 1,2,3,4,5-penta- thiacyclo-octane. One acyclic congener identified was dimethyl tetrasulfide.

  13. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize plant extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. However, th...

  14. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize phytochemicals in plant extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. New methods a...

  15. Collision-induced fragmentation accurate mass spectrometric analysis methods to rapidly characterize plant extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rapid advances in analytical chromatography equipment have made the reliable and reproducible measurement of a wide range of plant chemical components possible. Full chemical characterization of a given plant material is possible with the new mass spectrometers currently available. For phytochem...

  16. Spatially-Correlated Mass Spectrometric Analysis of Microbe-Mineral Interactions

    SciTech Connect

    Jill R. Scott; Beizhan Yan; Daphne L. Stoner

    2006-11-01

    A new methodology for examining the interactions of microbes with heterogeneous minerals is presented. Imaging laser-desorption Fourier transform mass spectrometry was used to examine the colonization patterns of Burkholderia vietnamiensis (Burkholderia cepacia) G4 on a heterogeneous basalt sample. Depth-profile imaging found that the bacterium preferentially colonized the plagioclase mineral phases within the basalt.

  17. Characterisation of archaeological waterlogged wood by pyrolytic and mass spectrometric techniques.

    PubMed

    Łucejko, Jeannette J; Modugno, Francesca; Ribechini, Erika; del Río, José C

    2009-11-03

    Two techniques based on analytical pyrolysis and mass spectrometry, direct exposure-MS (DE-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), were used to characterise waterlogged archaeological wood and to study degradation patterns of wood in aqueous environments. The two techniques were applied to samples from the excavation of the Site of the Ancient Ships of Pisa San Rossore in Pisa (Italy), and data were compared to those relative to native sound wood of the same species (pine, elm, beech). Both the methods result valuable in the analysis of ancient wood artefacts, avoiding the long wet-chemical procedures that are commonly used in wood analysis, and allowing us to use a minimal sample size. DE-MS achieves a global mass spectral fingerprint of lignin and polysaccharides pyrolysis compounds in few minutes, and the results have been interpreted with the support of principal component analysis (PCA) of mass spectra. Py-GC/MS permits detailed molecular analysis of pyrolysis compounds and highlights some chemical modifications of lignin in archaeological samples, as demethylation of both guaiacyl and syringyl lignin units. Both the techniques demonstrate consistent loss of polysaccharides in archaeological wood.

  18. OpenChrom: a cross-platform open source software for the mass spectrometric analysis of chromatographic data

    PubMed Central

    2010-01-01

    Background Today, data evaluation has become a bottleneck in chromatographic science. Analytical instruments equipped with automated samplers yield large amounts of measurement data, which needs to be verified and analyzed. Since nearly every GC/MS instrument vendor offers its own data format and software tools, the consequences are problems with data exchange and a lack of comparability between the analytical results. To challenge this situation a number of either commercial or non-profit software applications have been developed. These applications provide functionalities to import and analyze several data formats but have shortcomings in terms of the transparency of the implemented analytical algorithms and/or are restricted to a specific computer platform. Results This work describes a native approach to handle chromatographic data files. The approach can be extended in its functionality such as facilities to detect baselines, to detect, integrate and identify peaks and to compare mass spectra, as well as the ability to internationalize the application. Additionally, filters can be applied on the chromatographic data to enhance its quality, for example to remove background and noise. Extended operations like do, undo and redo are supported. Conclusions OpenChrom is a software application to edit and analyze mass spectrometric chromatographic data. It is extensible in many different ways, depending on the demands of the users or the analytical procedures and algorithms. It offers a customizable graphical user interface. The software is independent of the operating system, due to the fact that the Rich Client Platform is written in Java. OpenChrom is released under the Eclipse Public License 1.0 (EPL). There are no license constraints regarding extensions. They can be published using open source as well as proprietary licenses. OpenChrom is available free of charge at http://www.openchrom.net. PMID:20673335

  19. Mass spectrometric metabolomic imaging of biofilms on corroding steel surfaces using laser ablation and solvent capture by aspiration.

    PubMed

    Brauer, Jonathan I; Makama, Zakari; Bonifay, Vincent; Aydin, Egemen; Kaufman, Eric D; Beech, Iwona B; Sunner, Jan

    2015-03-02

    Ambient laser ablation and solvent capture by aspiration (LASCA) mass spectrometric imaging was combined with metabolomics high-performance liquid chromatography (HPLC) mass spectrometry analysis and light profilometry to investigate the correlation between chemical composition of marine bacterial biofilms on surfaces of 1018 carbon steel and corrosion damage of steel underneath the biofilms. Pure cultures of Marinobacter sp. or a wild population of bacteria present in coastal seawater served as sources of biofilms. Profilometry data of biofilm-free surfaces demonstrated heterogeneous distributions of corrosion damage. LASCA data were correlated with areas on the coupons varying in the level of corrosion attack, to reveal differences in chemical composition within biofilm regions associated with corroding and corrosion-free zones. Putative identification of selected compounds was carried out based on HPLC results and subsequent database searches. This is the first report of successful ambient chemical and metabolomic imaging of marine biofilms on corroding metallic materials. The metabolic analysis of such biofilms is challenging due to the presence in the biofilm of large amounts of corrosion products. However, by using the LASCA imaging interface, images of more than 1000 ions (potential metabolites) are generated, revealing striking heterogeneities within the biofilm. In the two model systems studied here, it is found that some of the patterns observed in selected ion images closely correlate with the occurrence and extent of corrosion in the carbon steel substrate as revealed by profilometry, while others do not. This approach toward the study of microbially influenced corrosion (MIC) holds great promise for approaching a fundamental understanding of the mechanisms involved in MIC.

  20. Mass Spectral Investigations on Toxins. 2. Simultaneous Detection and Quantification of Ultra-Trace Levels of Simple Trichothecenes in Environmental and Fermentation Samples by Gas Chromatographic/Negative Ion Chemical Ionization-Mass Spectrometric Techniques

    DTIC Science & Technology

    1987-01-01

    macrocyclic trichothecenes or semisynthetic compounds. Scirpentriol (3a-HOVER), deoxynivalenol (DON), fusarinon-X (FUSX), monoacetoxyscirpenol (MAS) and...S.R. Gas Chromhtog- raphy with Electron Capture and Mass Spectrometric Detection of Deoxynivalenol in Wheat and Other Grains. J. Assoc. Off. Anal. Chem

  1. On the implications of aerosol liquid water and phase separation for organic aerosol mass

    EPA Science Inventory

    Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to org...

  2. Optimization of quadrupole ion storage mass spectrometric conditions for the analysis of selected polybrominated diphenyl ethers. Comparative approach with negative chemical ionization and electron impact mass spectrometry.

    PubMed

    Larrazábal, David; Angeles Martínez, Ma; Eljarrat, Ethel; Barceló, Damiá; Fabrellas, Begoña

    2004-10-01

    Gas chromatography coupled to quadrupole ion storage mass spectrometry (QISTMS) operating in the non-resonant mode is presented as an innovative approach for the analysis of selected polybrominated diphenyl ethers (PBDEs). Although reductions in complexity and time needed for optimization are achieved in comparison with the resonant option, precise adjustment of the mass spectrometric conditions is required. Differences in isolation and fragmentation patterns of target species with degree of bromination were observed. The reliability of the method was confirmed by using standard solutions through the evaluation of certain quality parameters such as accuracy (92-108%), injection repeatability and reproducibility (coefficient of variation below 10% and 15%, respectively). Detection limits ranged from 62 to 621 fg, providing sensitivity similar to that of negative chemical ionisation (NCIMS) and greater than that of electron ionization mass spectrometry. The applicability of QISTMS method to real samples and matrix effects were evaluated through the analysis of some PBDE congeners in a sewage sludge sample from a Spanish waste-water treatment plant. Comparable results were obtained using QISTMS and NCIMS. According to these observations, QISTMS performed in the non-resonant mode may constitute a low-cost, rapid and reliable alternative to high-resolution devices for the analysis of selected PBDEs in environmental samples.

  3. Liquid chromatography/electrospray ionization mass spectrometric characterization of Harpagophytum in equine urine and plasma.

    PubMed

    Colas, Cyril; Garcia, Patrice; Popot, Marie-Agnès; Bonnaire, Yves; Bouchonnet, Stéphane

    2006-01-01

    A method has been developed for the analysis and characterization in equine urine and plasma of iridoid glycosides: harpagide, harpagoside and 8-para-coumaroyl harpagide, which are the main active principles of Harpagophytum, a plant with antiinflammatory properties. The method involves liquid chromatography coupled with positive electrospray ionization mass spectrometry. The addition of sodium or lithium chloride instead of formic acid in the eluting solvent has been studied in order to enhance the signal and to modify the ion's internal energy. Fragmentation pathways and associated patterns are proposed for each analyte. A comparison of three types of mass spectrometer: a 3D ion trap, a triple quadrupole and a linear ion trap, has been conducted. The 3D ion trap was selected for drug screening analysis whereas the linear ion trap was retained for identification and quantitation analysis.

  4. Developing mass spectrometric techniques for boundary layer measurement in hypersonic high enthalpy test facilities

    NASA Technical Reports Server (NTRS)

    Wood, G. M., Jr.; Lewis, B. W.; Nowak, R. J.; Eide, D. G.; Paulin, P. A.; Upchurch, B. T.

    1983-01-01

    Thermodynamic flow properties of gases in the boundary layer or the flowfield have been mainly deduced from pressures and temperatures measured on a model. However, further progress with respect to an understanding of these properties requires a more complete characterization of the layer including determination of the gas composition and chemistry. Most attempts to measure boundary layer chemistry involve the employment of a mass spectrometer and an associated gas sampling system. The three major limiting factors which must be addressed for species measurement in aerothermodynamic investigations on models at reentry stream velocities, are gas sampling effects, instrument limitations, and problems with data acquisition. The present investigation is concerned with a concentrated effort to quantitatively identify and correct for instrument and sampling system effects, and to develop a miniaturized high performance mass spectrometer for on-model real-time analysis of the boundary layer and its associated atmosphere.

  5. Mass Spectrometric Immunoassay for Parathyroid Hormone Related Protein (PTHrP)

    SciTech Connect

    Zheng, K.; Rivera, J.D.; Vogel, J.S.; Buchholz, B.A.; Burton, D.W.; Deftos, L.J.; Herold, D.A.; Fitzgerald, R.L.

    2000-06-16

    Many cancers, including prostate, breast and lung express parathyroid hormone related protein (PTHrP). Despite the common tumor overexpression of PTHrP, serum levels of PTHrP are not commonly elevated in affected patients. They postulate that the reasons for the discrepancy between tissue and serum measurements of PTHrP are the inadequate sensitivity and specificity of current PTHrP serum assays. To improve the clinical value of PTHrP serum assays for the cancer patient, they are developing a new generation of novel and ultrasensitive PTHrP serum immunoassays based on immunoaffinity purification, nanospray liquid chromatography tandem mass spectrometry (LC/MS/MS) and accelerator mass spectrometry (AMS).

  6. Rarefied gas dynamic effects on mass spectrometric studies of upper planetary atmospheres

    NASA Technical Reports Server (NTRS)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1975-01-01

    Results are presented of measurements obtained with an open-source mass spectrometer both in earth orbit and in a laboratory molecular beam facility. The mass spectrometer/ion source combination was developed in the laboratory to be operable in either of two modes by altering ion extraction potential on ground command, i.e., as a stagnation cavity or to respond only to the incoming molecules of the unperturbed atmosphere. Results indicate that the use of this open-source configuration and dual-mode capability, allied with both standard static calibration and dynamic calibration using high-speed molecular beam techniques in the laboratory, allows collection of useful data on aeronomy of the upper atmosphere of planets and comet tails.

  7. Mass Spectrometric Detection of Botulinum Neurotoxin by Measuring its Activity in Serum and Milk

    NASA Astrophysics Data System (ADS)

    Kalb, Suzanne R.; Pirkle, James L.; Barr, John R.

    Botulinum neurotoxins (BoNTs) are bacterial protein toxins which are considered likely agents for bioterrorism due to their extreme toxicity and high availability. A new mass spectrometry based assay called Endopep MS detects and defines the toxin serotype in clinical and food matrices via toxin activity upon a peptide substrate which mimics the toxin's natural target. Furthermore, the subtype of the toxin is differentiated by employing mass spectrometry based proteomic techniques on the same sample. The Endopep-MS assay selectively detects active BoNT and defines the serotype faster and with sensitivity greater than the mouse bioassay. One 96-well plate can be analyzed in under 7 h. On higher level or "hot" samples, the subtype can then be differentiated in less than 2 h with no need for DNA.

  8. Mass spectrometric methods prove the use of beeswax and ruminant fat in late Roman cooking pots.

    PubMed

    Kimpe, K; Jacobs, P A; Waelkens, M

    2002-08-30

    Lipid extracts of sherds of archaeological late Roman cooking pots were analysed using high temperature-gas chromatography coupled to a mass spectrometer and liquid chromatography with atmospheric pressure chemical ionization mass spectrometer detection (LC-APCI-MS). With these advanced techniques the use of beeswax was shown through identification of the constituting alkanes, mono and diesters. The detection of high amounts of saturated triacylglycerols (TAGs) further indicated that animal fat was processed in these pots. Part of the animal fat was characterised as originating from ruminants due to the presence of trans-fatty acids. The distribution of saturated TAGs and the higher concentration of stearic acid compared to palmitic acid in the transesterified lipid extract indicated that this was sheep fat. The results illustrate how complex mixtures can be unravelled and original contents of ancient ceramic vessels can be determined using specialised analytical equipment.

  9. Resonance ionization mass spectrometric study of the promethium/samarium isobaric pair

    SciTech Connect

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1988-01-01

    Samarium daughters are problematic in isotope ratio measurements of promethium because they are isobaric. Resonance ionization mass spectrometry was utilized to circumvent this problem. An ionization selectivity factor of at least 1000:1 has been measured for promethium over samarium at 584.6 nm. Resonance ionization spectra have been recorded for both elements over the 528-560 and 580-614 nm wavelength ranges.

  10. Gas chromatographic/mass spectrometric determination of lysergic acid diethylamide (LSD) in serum samples.

    PubMed

    Musshoff, F; Daldrup, T

    1997-08-04

    A sensitive method for the detection and quantification of lysergic acid diethylamide (LSD) in serum samples is described. After liquid-liquid extraction the trimethylsilyl derivative of LSD is detected by gas chromatography-mass spectrometry. Experiments with spiked samples resulted in a recovery of 76%, the coefficient of variation was 9.3%. Excellent linearity was obtained over the range 0.1-10 ng ml-1. Additionally experiments demonstrating the light sensitivity of LSD are presented together with casuistics.

  11. Mass spectrometric techniques for label-free high-throughput screening in drug discovery.

    PubMed

    Roddy, Thomas P; Horvath, Christopher R; Stout, Steven J; Kenney, Kristin L; Ho, Pei-I; Zhang, Ji-Hu; Vickers, Chad; Kaushik, Virendar; Hubbard, Brian; Wang, Y Karen

    2007-11-01

    High-throughput screening (HTS) is an important tool for finding active compounds to initiate medicinal chemistry programs in pharmaceutical discovery research. Traditional HTS methods rely on fluorescent or radiolabeled reagents and/or coupling assays to permit quantitation of enzymatic target inhibition or activation. Mass spectrometry-based high-throughput screening (MS-HTS) is an alternative that is not susceptible to the limitations imposed by labeling and coupling enzymes. MS-HTS offers a selective and sensitive analytical method for unlabeled substrates and products. Furthermore, method development times are reduced without the need to incorporate labels or coupling assays. MS-HTS also permits screening of targets that are difficult or impossible to screen by other techniques. For example, enzymes that are challenging to purify can lead to the nonspecific detection of structurally similar components of the impure enzyme or matrix of membraneous enzymes. The high selectivity of tandem mass spectrometry (MS/MS) enables these screens to proceed with low levels of background noise to sensitively discover interesting hits even with relatively weak activity. In this article, we describe three techniques that we have adapted for large-scale (approximately 175,000 sample) compound library screening, including four-way parallel multiplexed electrospray liquid chromatography tandem mass spectrometry (MUX-LC/MS/MS), four-way parallel staggered gradient liquid chromatography tandem mass spectrometry (LC/MS/MS), and eight-way staggered flow injection MS/MS following 384-well plate solid-phase extraction (SPE). These methods are capable of analyzing a 384-well plate in 37 min, with typical analysis times of less than 2 h. The quality of the MS-HTS approach is demonstrated herein with screening data from two large-scale screens.

  12. Mass-spectrometric determination of serum cortisol: comparison of data from two independent laboratories

    SciTech Connect

    Gaskell, S.J.; Sieckmann, L.

    1986-03-01

    Isotope dilution and mass spectrometry were used in two independent laboratories to determine cortisol in 15 plasma and serum pools used in the British and German national schemes for the external quality assessment of routine assays. For the concentration range 240-700 nmol/L, differences between the data obtained by the two laboratories were generally less than 4% but were approximately 7% in two instances. The discrepancies are nevertheless small in comparison with the bias observed for many routine assays.

  13. Rapid mass spectrometric DNA diagnostics for assessing microbial community activity during bioremediation. 1997 annual progress report

    SciTech Connect

    Benner, W.H.; Hunter-Cevera, J.

    1997-01-01

    'The effort of the past year''s activities, which covers the first year of the project, was directed at developing DNA-based diagnostic procedures for implementation in high through-put analytical instrumentation. The diagnostic procedures under evaluation are designed to identify specific genes in soil microorganisms that code for pollutant-degrading enzymes. Current DNA-based diagnostic procedures, such as the ligase chain reaction (LCR) and the polymerase chain reaction (PCR), rely on gel electrophoresis as a way to score a diagnostic test. The authors are attempting to implement time-of-flight (TOF) mass spectrometry as a replacement for gel separations because of its speed advantage and potential for sample automation. The authors anticipate that if TOF techniques can be implemented in the procedures, then a very large number of microorganisms and soil samples can be screened for the presence of specific pollutant-degrading genes. The use of DNA-based procedures for the detection of biodegrading organisms or genes that code for pollutant-degrading enzymes constitutes a critical technology for following biochemical transformation and substantiating the impact of bioremediation. DNA-based technology has been demonstrated to be a sensitive technique for tracking micro-organism activity at the molecular level. These procedures can be tuned to identify groups of organisms, specific organisms, and activity at the molecular level. They are developing a P-monitoring strategy that relies on the combined use of DNA diagnostics with mass spectrometry as the detection scheme. The intent of this work is a two-fold evaluation of (1) the feasibility of replacing the use of gel separations for identifying polymerase chain reaction (PCR) products with a rapid and automatable form of electrospray mass spectrometry and (2) the use of matrix-assisted-laser-desorption-ionization mass spectrometry (MALDI-MS) as a tool to score oligonucleotide ligation assays (OLA).'

  14. Biochemical Individuality Reflected in Chromatographic, Electrophoretic and Mass-Spectrometric Profiles

    PubMed Central

    Novotny, Milos V.; Soini, Helena A.; Mechref, Yehia

    2008-01-01

    This review discusses the current trends in molecular profiling for the emerging systems biology applications. Historically, the methodological developments in separation science were coincident with the availability of new ionization techniques in mass spectrometry. Coupling miniaturized separation techniques with technologically-advanced MS instrumentation and the modern data processing capabilities are at the heart of current platforms for proteomics, glycomics and metabolomics. These are being featured here by the examples from quantitative proteomics, glycan mapping and metabolomic profiling of physiological fluids. PMID:18551752

  15. Chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride

    SciTech Connect

    Not Available

    1981-01-01

    Analytical procedures, which are in routine use to determine conformance to uranium hexafluoride (UF/sub 6/) specifications in the Department of Energy gaseous diffusion plants or at other installations, are described in detail. Included are: subsampling of UF/sub 6/; gravimetric determination of uranium; titrimetric determination of uranium and of chlorine; preparation of high-purity U/sub 3/O/sub 8/; isotopic analysis by double-standard and by single-standard mass-spectrometer method; determination of hydrocarbons, chlorocarbons, and partially substituted halohydrocarbons; atomic absorption determination of antimony, ruthenium, and metallic impurities; spectrophotometric determination of bromine, silicon and phosphorus, titanium and vanadium, tungsten, thorium, and molybdenum; spectrographic determination of boron and silicon, ruthenium, thorium and rare earths; spectrographic determination of metallic impurities by carrier distillation; spectrographic determination of hafnium, molybdenum, niobium, tantalum, titanium, tungsten, vanadium, and zirconium after separation from UF/sub 6/ with BPHA and as cupferrides; impurity determination by spark-source mass spectrography; determination of boron-equivalent neutron cross section; determination of uranium-233 abundance by thermal ionization mass spectrometry; determination of uranium-232 by alpha spectrometry; determination of fission product activity by beta and gamma counting; determination of plutonium by ion exchange and alpha counting;determination of technetium-99 in UF/sub 6/; determination of gamma-energy emission rate from fission products in UF/sub 6/; determination of plutonium and neptunium by extraction and alpha counting; atomic absorption determination of chromium soluble and insoluble in UF/sub 6/. (JMT)

  16. Novel LC/MS/MS and High-Throughput Mass Spectrometric Assays for Monoacylglycerol Acyltransferase Inhibitors.

    PubMed

    Qi, Jenson; Masucci, John A; Lang, Wensheng; Connelly, Margery A; Caldwell, Gary W; Petrounia, Ioanna; Kirkpatrick, Jennifer; Barnakov, Alexander N; Struble, Geoffrey; Miller, Robyn; Dzordzorine, Keli; Kuo, Gee-Hong; Gaul, Michael; Pocai, Alessandro; Lee, Seunghun

    2017-04-01

    Monoacylglycerol acyltransferase enzymes (MGAT1, MGAT2, and MGAT3) convert monoacylglycerol to diacylglycerol (DAG). MGAT1 and MGAT2 are both implicated in obesity-related metabolic diseases. Conventional MGAT enzyme assays use radioactive substrates, wherein the product of the MGAT-catalyzed reaction is usually resolved by time-consuming thin layer chromatography (TLC) analysis. Furthermore, microsomal membrane preparations typically contain endogenous diacylglycerol acyltransferase (DGAT) from the host cells, and these DGAT activities can further acylate DAG to form triglyceride (TG). Our mass spectrometry (liquid chromatography-tandem mass spectrometry, or LC/MS/MS) MGAT2 assay measures human recombinant MGAT2-catalyzed formation of didecanoyl-glycerol from 1-decanoyl-rac-glycerol and decanoyl-CoA, to produce predominantly 1,3-didecanoyl-glycerol. Unlike 1,2-DAG, 1,3-didecanoyl-glycerol is proved to be not susceptible to further acylation to TG. 1,3-Didecanoyl-glycerol product can be readily solubilized and directly subjected to high-throughput mass spectrometry (HTMS) without further extraction in a 384-well format. We also have established the LC/MS/MS MGAT activity assay in the intestinal microsomes from various species. Our assay is proved to be highly sensitive, and thus it allows measurement of endogenous MGAT activity in cell lysates and tissue preparations. The implementation of the HTMS MGAT activity assay has facilitated the robust screening and evaluation of MGAT inhibitors for the treatment of metabolic diseases.

  17. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    NASA Astrophysics Data System (ADS)

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-07-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  18. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    DOE PAGES

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; ...

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguishmore » between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.« less

  19. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    SciTech Connect

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijhout, Falko P.

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  20. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    PubMed Central

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-01-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required. PMID:26156000

  1. Mass Spectrometric Quantification of Histone Post-translational Modifications by a Hybrid Chemical Labeling Method

    PubMed Central

    Maile, Tobias M.; Izrael-Tomasevic, Anita; Cheung, Tommy; Guler, Gulfem D.; Tindell, Charles; Masselot, Alexandre; Liang, Jun; Zhao, Feng; Trojer, Patrick; Classon, Marie; Arnott, David

    2015-01-01

    Mass spectrometry is a powerful alternative to antibody-based methods for the analysis of histone post-translational modifications (marks). A key development in this approach was the deliberate propionylation of histones to improve sequence coverage across the lysine-rich and hydrophilic tails that bear most modifications. Several marks continue to be problematic however, particularly di- and tri-methylated lysine 4 of histone H3 which we found to be subject to substantial and selective losses during sample preparation and liquid chromatography-mass spectrometry. We developed a new method employing a “one-pot” hybrid chemical derivatization of histones, whereby an initial conversion of free lysines to their propionylated forms under mild aqueous conditions is followed by trypsin digestion and labeling of new peptide N termini with phenyl isocyanate. High resolution mass spectrometry was used to collect qualitative and quantitative data, and a novel web-based software application (Fishtones) was developed for viewing and quantifying histone marks in the resulting data sets. Recoveries of 53 methyl, acetyl, and phosphoryl marks on histone H3.1 were improved by an average of threefold overall, and over 50-fold for H3K4 di- and tri-methyl marks. The power of this workflow for epigenetic research and drug discovery was demonstrated by measuring quantitative changes in H3K4 trimethylation induced by small molecule inhibitors of lysine demethylases and siRNA knockdown of epigenetic modifiers ASH2L and WDR5. PMID:25680960

  2. Flavonoids as matrices for MALDI-TOF mass spectrometric analysis of transition metal complexes

    NASA Astrophysics Data System (ADS)

    Petkovic, Marijana; Petrovic, Biljana; Savic, Jasmina; Bugarcic, Zivadin D.; Dimitric-Markovic, Jasmina; Momic, Tatjana; Vasic, Vesna

    2010-02-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a suitable method for the analysis of inorganic and organic compounds and biomolecules. This makes MALDI-TOF MS convenient for monitoring the interaction of metallo-drugs with biomolecules. Results presented in this manuscript demonstrate that flavonoids such as apigenin, kaempferol and luteolin are suitable for MALDI-TOF MS analysis of Pt(II), Pd(II), Pt(IV) and Ru(III) complexes, giving different signal-to-noise ratios of the analyte peak. The MALDI-TOF mass spectra of inorganic complexes acquired with these flavonoid matrices are easy to interpret and have some advantages over the application of other commonly used matrices: a low number of matrix peaks are detectable and the coordinative metal-ligand bond is, in most cases, preserved. On the other hand, flavonoids do not act as typical matrices, as their excess is not required for the acquisition of MALDI-TOF mass spectra of inorganic complexes.

  3. MISR Aerosol Air Mass Type Mapping over Mega-City: Validation and Applications

    NASA Astrophysics Data System (ADS)

    Patadia, F.; Kahn, R. A.

    2010-12-01

    Most aerosol air-quality monitoring in mega-city environments is done from scattered ground stations having detailed chemical and optical sampling capabilities. Satellite instruments such as the Multi-angle Imaging SpectroRadiometer (MISR) can retrieve total-column Aerosol Optical Depth (AOD), along with some information about particle microphysical properties. Although the particle property information from MISR is much less detailed than that obtained from the ground sampling stations, the coverage is extensive, making it possible to put individual surface observations into the context of regional aerosol air mass types. This paper presents an analysis of MISR aerosol observations made coincident with aircraft and ground-based instruments during the INTEX-B field campaign. These detailed comparisons of satellite aerosol property retrievals against dedicated field measurements provide the opportunity to validate the retrievals quantitatively at a regional level, and help to improve aerosol representation in retrieval algorithms. Validation of MISR retrieved AOD and other aerosol properties over the INTEX-B study region in and around Mexico City will be presented. MISR’s ability to distinguish among aerosol air mass types will be discussed. The goal of this effort is to use the MISR aerosol property retrievals for mapping both aerosol air mass type and AOD gradients in mega-city environments over the decade-plus that MISR has made global observations.

  4. Organic Mass Fragments and Organic Functional Groups in Aged Biomass Burning and Fossil Fuel Combustion Aerosol

    NASA Astrophysics Data System (ADS)

    Day, D. A.; Hawkins, L. N.; Russell, L. M.

    2009-12-01

    Organic functional group concentrations in submicron aerosol particles collected from 27 June to 17 September at the Scripps Pier in La Jolla, California as part of AeroSCOPE 2008 were quantified using Fourier Transform Infrared (FTIR) spectroscopy. Organic and inorganic non-refractory components in the same air masses were quantified using a Quadrupole Aerosol Mass Spectrometer (Q-AMS). Previous measurements at the Scripps pier indicate that a large fraction of submicron particle mass originates in Los Angeles and the port of Long Beach. Additional particle sources to the region include local urban emissions and periodic biomass burning during large wildfires. Three distinct types of organic aerosol components were identified from organic composition and elemental tracers, including biomass burning, fossil fuel combustion, and polluted marine components. Fossil fuel combustion organic aerosol was dominated by unsaturated alkane and was correlated with sulfur, vanadium, and nickel supporting ship and large trucks in and around the Los Angeles/Long Beach region as the dominant source. Biomass burning organic aerosol comprised a smaller unsaturated alkane fraction and larger fractions of non-acid carbonyl, amine, and carboxylic acid and was correlated with potassium and bromine. Polluted marine organic aerosol was dominated by organic hydroxyl and unsaturated alkane and was not correlated with any elemental tracers. Mass spectra of the organic aerosol support the aerosol sources determined by organic functional groups and elemental tracers and contain fragments commonly attributed to oxygenated organic aerosol (OOA), hydrocarbon-like organic aerosol (HOA), and biomass burning organic aerosol (BBOA). Comparisons of the PMF-derived Q-AMS source spectra with FTIR source spectra and functional group composition provide additional information on the relationship between commonly reported organic aerosol factors and organic functional groups in specific organic aerosol

  5. Capillary liquid chromatography using laser-based and mass spectrometric detection. Final technical progress report, September 1, 1989--January 31, 1993

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-09-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  6. Mass spectrometric characterization of a prolyl hydroxylase inhibitor GSK1278863, its bishydroxylated metabolite, and its implementation into routine doping controls.

    PubMed

    Thevis, Mario; Milosovich, Susan; Licea-Perez, Hermes; Knecht, Dana; Cavalier, Tom; Schänzer, Wilhelm

    2016-08-01

    Drug candidates, which have the potential of enhancing athletic performance represent a risk of being misused in elite sport. Therefore, there is a need for early consideration by anti-doping authorities and implementation into sports drug testing programmes. The hypoxia-inducible factor (HIF) or prolyl hydroxylase inhibitor (PHI) GSK1278863 represents an advanced candidate of an emerging class of therapeutics that possess substantial potential for abuse in sport due to their capability to stimulate the biogenesis of erythrocytes and, consequently, the individual's oxygen transport capacity. A thorough characterization of such analytes by technologies predominantly used for doping control purposes and the subsequent implementation of the active drug and/or its main urinary metabolite(s) are vital for comprehensive, preventive, and efficient anti-doping work. In the present study, the HIF PHI drug candidate GSK1278863 (comprising a 6-hydroxypyrimidine-2,4-dione nucleus) and its bishydroxylated metabolite M2 (GSK2391220A) were studied regarding their mass spectrometric behaviour under electrospray ionization (ESI-MS/MS) conditions. Synthesized reference materials were used to elucidate dissociation pathways by means of quadrupole/time-of-flight high resolution/high accuracy tandem mass spectrometry, and their detection from spiked urine and elimination study urine samples under routine doping control conditions was established using liquid chromatography-electrospray ionization-tandem mass spectrometry with direct injection. Dissociation pathways to diagnostic product ions of GSK1278863 (e.g. m/z 291, 223, and 122) were proposed as substantiated by determined elemental compositions and MS(n) experiments as well as comparison to spectra of the bishydroxylated analogue M2. An analytical assay based on direct urine injection using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of GSK1278863 in

  7. Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane

    SciTech Connect

    Jewett, J.R., Fluor Daniel Hanford

    1997-02-24

    Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

  8. Doping control analysis of trimetazidine and characterization of major metabolites using mass spectrometric approaches.

    PubMed

    Sigmund, Gerd; Koch, Anja; Orlovius, Anne-Katrin; Guddat, Sven; Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    Since January 2014, the anti-anginal drug trimetazidine [1-(2,3,4-trimethoxybenzyl)-piperazine] has been classified as prohibited substance by the World Anti-Doping Agency (WADA), necessitating specific and robust detection methods in sports drug testing laboratories. In the present study, the implementation of the intact therapeutic agent into two different initial testing procedures based on gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) is reported, along with the characterization of urinary metabolites by electrospray ionization-high resolution/high accuracy (tandem) mass spectrometry. For GC-MS analyses, urine samples were subjected to liquid-liquid extraction sample preparation, while LC-MS/MS analyses were conducted by established 'dilute-and-inject' approaches. Both screening methods were validated for trimetazidine concerning specificity, limits of detection (0.5-50 ng/mL), intra-day and inter-day imprecision (<20%), and recovery (41%) in case of the GC-MS-based method. In addition, major metabolites such as the desmethylated trimetazidine and the corresponding sulfoconjugate, oxo-trimetazidine, and trimetazidine-N-oxide as identified in doping control samples were used to complement the LC-MS/MS-based assay, although intact trimetazidine was found at highest abundance of the relevant trimetazidine-related analytes in all tested sports drug testing samples. Retrospective data mining regarding doping control analyses conducted between 1999 and 2013 at the Cologne Doping Control Laboratory concerning trimetazidine revealed a considerable prevalence of the drug particularly in endurance and strength sports accounting for up to 39 findings per year.

  9. A Mass-Spectrometric Investigation of the Chemistry of Advanced Composite and Double Base Propellants.

    DTIC Science & Technology

    1978-08-01

    reaction can be identified if they effuse into the molecular beam to the mass spectrometer. Also, intermediate species having a short lifetime (on the...ammonium perchlorate decomposition. The reaction between Pb 3 0 4 and carbon to produce the lead atom along with CO is extremely exothermic. This... reaction , Pb30 4 (c) + 4C(s) = 3Pb(l) + 4CO(g), has a free energy of -446.8 kJ at 1000 K. The lead compounds identified included PbCl, PbCIO and PbNO 2

  10. New FORTRAN computer programs to acquire and process isotopic mass spectrometric data: Operator`s manual

    SciTech Connect

    Smith, D.H.; McKown, H.S.

    1993-09-01

    This TM is one of a pair that describes ORNL-developed software for acquisition and processing of isotope ratio mass spectral data. This TM is directed at the laboratory analyst. No technical knowledge of the programs and programming is required. It describes how to create and edit files, how to acquire and process data, and how to set up files to obtain the desired results. The aim of this TM is to serve as a utilitarian instruction manual, a {open_quotes}how to{close_quotes} approach rather than a {open_quotes}why?{close_quotes}

  11. Formation and thermodynamics of gaseous germanium and tin vanadates: a mass spectrometric and quantum chemical study.

    PubMed

    Shugurov, S M; Panin, A I; Lopatin, S I; Emelyanova, K A

    2015-06-07

    The stabilities of gaseous germanium and tin vanadates were confirmed by high temperature mass spectrometry, and its structures were determined by quantum chemical calculations. A number of gas-phase reactions involving these gaseous salts were studied. On the basis of the equilibrium constants, the standard formation enthalpies of gaseous GeV2O6 (-1520 ± 42 kJ mol(-1)) and SnV2O6 (-1520 ± 43 kJ mol(-1)) were determined at a temperature of 298 K.

  12. Thermodynamic properties of spinel MgAl2O4: A mass spectrometric study

    NASA Astrophysics Data System (ADS)

    Shornikov, S. I.

    2017-02-01

    The activities of oxides in stoichiometric spinel MgAl2O4 in the temperature range 1851-2298 K were determined from the data obtained by the Knudsen effusion mass spectrometry. The resulting Gibbs energies of spinel formation from simple oxides, the enthalpies and entropies of spinel formation from simple oxides (-12.02 ± 1.14 kJ/mol and 5.03 ± 0.56 J/(mol K), respectively), and the spinel melting enthalpy (55.81 ± 4.62 kJ/mol) satisfactorily agree with the available thermodynamic data.

  13. Mass spectrometric study of the mercury isotopes in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Nier, A. O.; Schlutter, D. J.

    1986-01-01

    Isotopic abundance ratios for mercury were determined by mass spectrometry in six samples of bulk material and in one sample of chondrules from the Allende meteorite. A primary purpose of the work was to attempt to verify the anomalous ratios reported for Hg-196/Hg-202 by neutron activation. Measurements were made on the mercury released at temperatures of 250, 450, 600 C, and in some cases, higher temperatures. The precision of the measurements was such that if an anomaly of the magnitude reported exists, it should have been seen. The isotopic abundance ratios for the other mercury isotopes were also measured. Within the errors of measurement these agreed with normal terrestrial values.

  14. Mass spectrometric study of the evaporation of MgAl2O4 spinel

    NASA Astrophysics Data System (ADS)

    Shornikov, S. I.

    2017-01-01

    The evaporation of MgAl2O4 spinel is studied via high-temperature Knudsen effusion mass spectrometry in the temperature range of 1850-2250 K. In the gas phase, molecular components typical of the simple oxides in the spinel and traces of gaseous complex oxide MgAlO are identified above the samples. The resulting values of the partial vapor pressures of the molecular components contained in the gas phase over the spinel are compared with those corresponding to simple oxides for the first time.

  15. New mass-spectrometric facility for the analysis of highly radioactive samples

    SciTech Connect

    Warmack, R.J.; Landau, L.; Christie, W.H.; Carter, J.A.

    1981-01-01

    A new facility has been completed for the analysis of highly radioactive, gamma-emitting solid samples. A commercial spark-source mass spectrometer was adapted for remote handling and loading. Electrodes are prepared in a hot cell and transported to the adjacent lead-shielded source for analysis. The source was redesigned for ease of shielding, loading, and maintenance. Both solutions and residues from irradiated nuclear fuel dissolutions have been analyzed for elemental concentrations to < 1 ppM; isotopic data have also been obtained.

  16. Gas chromatographic-mass spectrometric analysis of creosotes extracted from wooden sleepers installed in playgrounds

    SciTech Connect

    Rotard, W.; Mailahn, W.

    1987-01-01

    In order to evaluate their hygienic risk, wood samples from sleepers (railroad cross ties) impregnated with coal tar creosote were taken from playgrounds and investigated for hazardous compounds. The samples were extracted with ether, and acid-base-neutral separations were made on the creosote extracts. Water-soluble compounds were also isolated. All the fractions were investigated by capillary gas chromatography-mass spectrometry. Besides phenols in the acidic fractions and N-heterocyclic polynuclear aromatic hydrocarbons (PAH) in the basic fractions, high amounts of neutral PAH and also, in several samples high levels of carcinogenic and cocarcinogenic PAH were determined.

  17. Gas chromatographic-mass spectrometric assay for 6-hydroxymelatonin sulfate and 6-hydroxymelatonin glucuronide in urine

    SciTech Connect

    Francis, P.L.; Leone, A.M.; Young, I.M.; Stovell, P.; Silman, R.E.

    1987-04-01

    Circulating melatonin is hydroxylated to 6-hydroxymelatonin and excreted in urine as the sulfate and glucuronide conjugates. We extracted these two compounds from urine by using octadecylsilane-bonded silica cartridges to eliminate most of the urea and electrolytes, and silica cartridges to separate the sulfate and glucuronide conjugates. After hydrolyzing the separated conjugates enzymically, we determined the free hydroxymelatonin by gas chromatography-mass spectrometry. Though recoveries were low and variable, we were able to quantify the analyte in the original sample by adding deuterated sulfate and glucuronide conjugates to the urines before extraction.

  18. Mass spectrometric analysis of putative capa-gene products in Musca domestica and Neobellieria bullata.

    PubMed

    Predel, Reinhard; Russell, William K; Tichy, Shane E; Russell, David H; Nachman, Ronald J

    2003-10-01

    Neuropeptides of the capa-gene are typical of the abdominal neurosecretory system of insects. In this study, we investigated these peptides in two widely distributed and large pest flies, namely Musca domestica and Neobellieria bullata. Using a combination of MALDI-TOF and ESI-QTOF mass spectrometry, periviscerokinins and a pyrokinin were analyzed from single perisympathetic organ preparations. The species-specific peptide sequences differ remarkably between the related dipteran species. These differences could make it possible to develop peptide-analogs with group- or species-specific efficacy.

  19. Engineering cell-compatible paper chips for cell culturing, drug screening, and mass spectrometric sensing.

    PubMed

    Chen, Qiushui; He, Ziyi; Liu, Wu; Lin, Xuexia; Wu, Jing; Li, Haifang; Lin, Jin-Ming

    2015-10-28

    Paper-supported cell culture is an unprecedented development for advanced bioassays. This study reports a strategy for in vitro engineering of cell-compatible paper chips that allow for adherent cell culture, quantitative assessment of drug efficiency, and label-free sensing of intracellular molecules via paper spray mass spectrometry. The polycarbonate paper is employed as an excellent alternative bioscaffold for cell distribution, adhesion, and growth, as well as allowing for fluorescence imaging without light scattering. The cell-cultured paper chips are thus amenable to fabricate 3D tissue construction and cocultures by flexible deformation, stacks and assembly by layers of cells. As a result, the successful development of cell-compatible paper chips subsequently offers a uniquely flexible approach for in situ sensing of live cell components by paper spray mass spectrometry, allowing profiling the cellular lipids and quantitative measurement of drug metabolism with minimum sample pretreatment. Consequently, the developed paper chips for adherent cell culture are inexpensive for one-time use, compatible with high throughputs, and amenable to label-free and rapid analysis.

  20. Electrophoretic Separation-Mass Spectrometric Detection on Polymer Microchip Directly Integrated with a Nanospray Tip

    NASA Astrophysics Data System (ADS)

    Kitagawa, Fumihiko; Shinohara, Hidetoshi; Mizuno, Jun; Otsuka, Koji; Shoji, Shuichi

    We fabricated a polymer chip for microchip electrophoresis-mass spectrometry (MCE—MS). As a substrate material, cycloolefin polymer (COP) was selected due to its high chemical durability and easy metallization for the electrode. A COP microchip with a conventional cross-type channel configuration for the MCE separation was fabricated by hot embossing. After bonding with a rid substrate, a nano electrospray ionization (nano-ESI) tip structure for MS detection was machined directly at the opening of the separation channel end. A gold electrode to keep the electric contact for ESI was deposited around the nanospray tip by electron beam evaporation. When the voltage of 3.0 and 2.0 kV was applied to the inlet and the ESI electrode, respectively, the formation of Taylor cone and stable electrospray were observed at the channel opening. In infusion analysis of caffeine, the MS spectrum with parent mass number of 195, which accords with that of the protonated caffeine, was successfully obtained in the positive mode. Furthermore, the MCE separation and ESI-MS detection of caffeine and arginine was also successfully achieved with resolution of 1.0. Therefore, these results demonstrated that the fabricated microchip integrated with the nano-ESI tip can be employed as the MCE—ESI-MS device.

  1. Sequence microheterogeneity of parvalbumin pI 5.0 of pike: a mass spectrometric study.

    PubMed

    Permyakov, Sergei E; Karnoup, Anton S; Bakunts, Anush G; Permyakov, Eugene A

    2009-01-01

    Parvalbumin (PA) is a muscle and neuronal calcium-binding protein, the major fish and frog allergen. Its characteristic feature is the presence of multiple isoforms with significantly different amino acid sequences. Here we show that the major isoform of northern pike muscle PA (pI 5.0, alpha-PA) exhibits microheterogeneity of amino acid sequence. ESI Q-TOF mass-spectrometry (MS) analysis of alpha-PA sample showed the presence of two components with mass difference of 71 Da. Analysis of tryptic and endoproteinase Asp-N digests of alpha-PA by MALDI-TOF MS revealed peptides, corresponding to two different amino acid sequences. The sequence differences between variant proteins are limited to AB-domain and include substitutions K27A and L31K, and an extra Leu residue between K11 and K12. Since the affected residues comprise a cluster on the surface of PA, an involvement of the identified region into target recognition is suggested. The substitutions at positions 27 and 31 are located in the region of previously identified epitopes of parvalbumin relevant for PA-specific IgE and IgG binding, which suggests different immunoactivities of the variants. The found microheterogeneity of PA is suggested to be of importance for physiological adaptation of the propulsive musculature to developmental and/or environmental requirements and may contribute to PA allergenicity.

  2. Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing☆

    PubMed Central

    Eduardoff, Mayra; Huber, Gabriela; Bayer, Birgit; Schmid, Dagmar; Anslinger, Katja; Göbel, Tanja; Zimmermann, Bettina; Schneider, Peter M.; Röck, Alexander W.; Parson, Walther

    2013-01-01

    In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context. PMID:24054029

  3. Tandem mass spectrometric analysis of a complex triterpene saponin mixture of Chenopodium quinoa.

    PubMed

    Madl, Tobias; Sterk, Heinz; Mittelbach, Martin; Rechberger, Gerald N

    2006-06-01

    A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) approach was applied to a complex crude triterpene saponin extract of Chenopodium quinoa seed coats. In ESI-MS/MS spectra of triterpene saponins, characteristic fragmentation reactions are observed and allow the determination of aglycones, saccharide sequences, compositions, and branching. Fragmentation of aglycones provided further structural information. The chemical complexity of the mixture was resolved by a complete profiling. Eighty-seven triterpene saponins comprising 19 reported and 68 novel components were identified and studied by MS. In addition to four reported, five novel triterpene aglycones were detected and characterized according to their fragmentation reactions in ESI-MS/MS and electron ionization mass spectrometry (EI-MS). As a novelty fragmentation pathways were proposed and analyzed based upon quantum chemical calculations using a hybrid Hartree-Fock density functional method. Accuracy of the assignment procedure was proven by isolation and structure determination of a novel compound. As the relative distribution and composition of saponins varies between different cultivars and soils, the presented strategy allows a rapid and complete analysis of Chenopodium quinoa saponin distribution and composition, and is particularly suitable for quality control and screening of extracts designated for pharmaceutical, agricultural, and industrial applications.

  4. Quantitation of tetrahydrocannabinol in hair using immunoassay and liquid chromatography with tandem mass spectrometric detection.

    PubMed

    Coulter, Cynthia; Taruc, Margaux; Tuyay, James; Moore, Christine

    2009-05-01

    A quantitative analytical procedure for the determination of Delta(9)-tetrahydrocannabinol (THC) in hair has been developed and validated using liquid chromatography with tandem mass spectral detection (LC-MS/MS). Specimens that were determined as containing cannabinoids following immunoassay testing were quantified using solid-phase extraction followed by liquid chromatographic separation and tandem mass spectral detection in positive electrospray ionization mode. For confirmation, two transitions were monitored and one ratio determined. Samples being reported as positive were required to have both transitions present, the ratio of quantifying transition to qualifying transition being within 20% of that determined from known calibration standards. The limit of quantitation and the limit of detection was 10 pg/mg. The percentage recovery of the THC from hair at 20 pg/mg was 56% and a matrix effect of the hair showed an ion suppression percentage of -51%. The immunochemical screening method was performed following a rapid aqueous extraction, requiring only 10 mg of hair; the confirmatory procedure required 20 mg of hair. The methods were applied to proficiency specimens from the Society of Hair Testing, which had been received in August 2008.

  5. Application of a Mass Spectrometric Approach to Detect the Presence of Fatty Acid Biosynthetic Phosphopeptides.

    PubMed

    Lau, Benjamin Yii Chung; Clerens, Stefan; Morton, James D; Dyer, Jolon M; Deb-Choudhury, Santanu; Ramli, Umi Salamah

    2016-04-01

    The details of plant lipid metabolism are relatively well known but the regulation of fatty acid production at the protein level is still not understood. Hence this study explores the importance of phosphorylation as a mechanism to control the activity of fatty acid biosynthetic enzymes using low and high oleic acid mesocarps of oil palm fruit (Elaeis guineensis variety of Tenera). Adaptation of neutral loss-triggered tandem mass spectrometry and selected reaction monitoring to detect the neutral loss of phosphoric acid successfully found several phosphoamino acid-containing peptides. These peptides corresponded to the peptides from acetyl-CoA carboxylase and 3-enoyl-acyl carrier protein reductase as identified by their precursor ion masses. These findings suggest that these enzymes were phosphorylated at 20th week after anthesis. Phosphorylation could have reduce their activities towards the end of fatty acid biosynthesis at ripening stage. Implication of phosphorylation in the regulation of fatty acid biosynthesis at protein level has never been reported.

  6. Nanopatterned Extracellular Matrices Enable Cell-Based Assays with a Mass Spectrometric Readout.

    PubMed

    Cabezas, Maria D; Mirkin, Chad A; Mrksich, Milan

    2017-03-08

    Cell-based assays are finding wider use in evaluating compounds in primary screens for drug development, yet it is still challenging to measure enzymatic activities as an end point in a cell-based assay. This paper reports a strategy that combines state-of-the-art cantilever free polymer pen lithography (PPL) with self-assembled monolayer laser desorption-ionization (SAMDI) mass spectrometry to guide cell localization and measure cellular enzymatic activities. Experiments are conducted with a 384 spot array, in which each spot is composed of ∼400 nanoarrays and each array has a 10 × 10 arrangement of 750 nm features that present extracellular matrix (ECM) proteins surrounded by an immobilized phosphopeptide. Cells attach to the individual nanoarrays, where they can be cultured and treated with small molecules, after which the media is removed and the cells are lysed. Phosphatase enzymes in the proximal lysate can then act on the immobilized phosphopeptide substrate to convert it to the dephosphorylated form. After the lysate is removed, the array is analyzed by SAMDI mass spectrometry to identify the extent of dephosphorylation and, therefore, the amount of enzyme activity in the cell. This novel approach of using nanopatterning to mediate cell adhesion and SAMDI to record enzyme activities in the proximal lysate will enable a broad range of cellular assays for applications in drug discovery and research not possible with conventional strategies.

  7. The effect of metal ions on Staphylococcus aureus revealed by biochemical and mass spectrometric analyses.

    PubMed

    Chudobova, Dagmar; Dostalova, Simona; Ruttkay-Nedecky, Branislav; Guran, Roman; Rodrigo, Miguel Angel Merlos; Tmejova, Katerina; Krizkova, Sona; Zitka, Ondrej; Adam, Vojtech; Kizek, Rene

    2015-01-01

    In this study, we focused on the effect of heavy metal ions in resistant strains of gram-positive bacteria Staphylococcus aureus using biochemical methods and mass spectrometry. Five nitrate solutions of heavy metals (Ag(+), Cu(2+), Cd(2+), Zn(2+) and Pb(2+)) were used to create S. aureus resistant strains. Biochemical changes of resistant strains in comparison with the non-resistant control strain of S. aureus were observed by microbiological (measuring - growth curves and inhibition zones) and spectrophotometric methods (antioxidant activity and alaninaminotransferase, aspartateaminotransferase, alkaline phosphatase, γ-glutamyltransferase activities). Mass spectrometry was employed for the qualitative analysis of the samples (changes in S. aureus protein composition) and for the identification of the strains database MALDI Biotyper was employed. Alterations, in terms of biochemical properties and protein composition, were observed in resistant strains compared to non-resistant control strain. Our results describe the possible option for the analysis of S. aureus resistant strains and may thus serve as a support for monitoring of changes in genetic information caused by the forming of resistance to heavy metals.

  8. Integrated Microfluidic Aptasensor for Mass Spectrometric Detection of Vasopressin in Human Plasma Ultrafiltrate.

    PubMed

    Yang, J; Zhu, J; Pei, R; Oliver, J A; Landry, D W; Stojanovic, M N; Lin, Q

    2016-07-14

    We present a microfluidic aptamer-based biosensor for detection of low-molecular-weight biomarkers in patient samples. Using a microfluidic device that integrates aptamer-based specific analyte extraction, isocratic elution, and detection by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, we demonstrate rapid, sensitive and label-free detection of arginine vasopressin (AVP) in human plasma ultrafiltrate. AVP molecules in complex matrices are specifically captured by an aptamer that is immobilized on microbeads via affinity binding in a microchamber. After the removal of unbound, contaminating molecules through washing, aptamer-AVP complexes are thermally disrupted via on-chip temperature control. Released AVP molecules are eluted with purified water and transferred to a separate microchamber, and deposited onto a single spot on a MALDI plate via repeated, piezoelectrically actuated ejection, which enriches AVP molecules over the spot area. This integrated on-chip sample processing enables the quantitative detection of low-abundance AVP by MALDI-TOF mass spectrometry in a rapid and label-free manner. Our experimental results show the detection of AVP in human plasma ultrafiltrate as low as physiologically relevant picomolar concentrations via aptamer-based selective preconcentration, demonstrating the potential of our approach as a rapid (~ 1hr), sensitive clinical AVP assay.

  9. Mass spectrometric investigation of the vaporization of sodium and potassium chromates: Preliminary results

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Kohl, F. J.; Miller, R. A.; Fryburg, G. C.

    1979-01-01

    Knudsen cell mass spectrometry was used to study the vaporization of sodium and potassium chromates. For both salts, the vaporization proceeds predominately by the reactions M2CrO4(c)=2M(g)+5/4O2(g)+1/2 Cr203(s) and M2CrO4(c)=M2CrO4(g) where M = Na or K. The distribution of the ions M(+), O2(+) and M2CrO4(+) in the measured mass spectrum was found to depend on the material used for the Knudsen cell, even for materials such as platinum and gold. In the case of sodium chromate, the decomposition reaction appears to be less important than the molecular vaporization reaction. A preliminary value of 72 kcal/mole at 1141 K was measured for the heat of the molecular vaporization reaction for sodium chromate. In the case of potassium chromate, it has not been possible to conclude which mode of vaporization dominates. For potassium chromate a value of 101 kcal/mole at 1173 K was obtained for the heat of the molecular vaporization reaction.

  10. Comparison of analysis of vitamin D3 in foods using ultraviolet and mass spectrometric detection.

    PubMed

    Byrdwell, William C

    2009-03-25

    A method for analysis of vitamin D(3) in commonly fortified foods and in fish, which contains endogenous vitamin D(3), was developed by combining the best aspects of two official methods. The ethyl ether/petroleum ether extraction procedure from AOAC 992.26 was combined with the chromatographic separation and use of an internal standard (vitamin D(2)) from AOAC 2002.05 to produce a method that was applicable to a variety of food samples. Results for skim milk, orange juice, breakfast cereal, salmon, a diluted USP reference standard (vitamin D(3) in peanut oil), and processed cheese are presented. Results indicated that UV detection was adequate in most cases, but the absence of interfering species must be determined in each food by mass spectrometry. Selected ion monitoring (SIM) atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) was shown to produce statistically indistinguishable results compared to UV detection for the skim milk, orange juice, multigrain cereal, and salmon samples. The processed cheese exhibited interferences that precluded quantification of vitamin D(3) by UV detection, and therefore, only SIM APCI-MS data for that sample were valid.

  11. Revisiting the quantitative features of surface-assisted laser desorption/ionization mass spectrometric analysis.

    PubMed

    Wu, Ching-Yi; Lee, Kai-Chieh; Kuo, Yen-Ling; Chen, Yu-Chie

    2016-10-28

    Surface-assisted laser desorption/ionization (SALDI) coupled with mass spectrometry (MS) is frequently used to analyse small organics owing to its clean background. Inorganic materials can be used as energy absorbers and the transfer medium to facilitate the desorption/ionization of analytes; thus, they are used as SALDI-assisting materials. Many studies have demonstrated the usefulness of SALDI-MS in quantitative analysis of small organics. However, some characteristics occurring in SALDI-MS require certain attention to ensure the reliability of the quantitative analysis results. The appearance of a coffee-ring effect in SALDI sample preparation is the primary factor that can affect quantitative SALDI-MS analysis results. However, to the best of our knowledge, there are no reports relating to quantitative SALDI-MS analysis that discuss or consider this effect. In this study, the coffee-ring effect is discussed using nanoparticles and nanostructured substrates as SALDI-assisting materials to show how this effect influences SALDI-MS analysis results. Potential solutions for overcoming the existing problems are also suggested.This article is part of the themed issue 'Quantitative mass spectrometry'.

  12. Mass Spectrometric Approaches to the Identification of Potential Ingredients in Cigarette Smoke Causing Cytotoxicity.

    PubMed

    Horiyama, Shizuyo; Kunitomo, Masaru; Yoshikawa, Noriko; Nakamura, Kazuki

    2016-01-01

    Cigarette smoke contains many harmful chemicals that contribute to the pathogenesis of smoking-related diseases such as chronic obstructive pulmonary disease, cancer, and cardiovascular disease. Many studies have been done to identify cytotoxic chemicals in cigarette smoke and elucidate the onset of the above-mentioned diseases caused by smoking. However, definitive mechanisms for cigarette smoke toxicity remain unknown. As candidates for cytotoxic chemicals, we have recently found methyl vinyl ketone (MVK) and acetic anhydride in nicotine/tar-free cigarette smoke extract (CSE) using L-tyrosine (Tyr), an amino acid with highly reactive hydroxyl group. The presence of MVK and acetic anhydride in CSE was confirmed by gas chromatography-mass spectrometry (GC/MS). We also found new reaction products formed in B16-BL6 mouse melanoma (B16-BL6) cells treated with CSE using LC/MS. These were identified as glutathione (GSH) conjugates of α,β-unsaturated carbonyl compounds, MVK, crotonaldehyde (CA), and acrolein (ACR), by the mass value and product ion spectra of these new products. ACR and MVK are type-2 alkenes, which are well known as electron acceptors and form Michael-type adducts to nucleophilic side chain of amino acids on peptides. These α,β-unsaturated carbonyl compounds may have a key role in CSE-induced cell death.

  13. Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing.

    PubMed

    Eduardoff, Mayra; Huber, Gabriela; Bayer, Birgit; Schmid, Dagmar; Anslinger, Katja; Göbel, Tanja; Zimmermann, Bettina; Schneider, Peter M; Röck, Alexander W; Parson, Walther

    2013-12-01

    In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry (ESI-MS) system (PLEX-ID) to an mtDNA population study to compare its performance with respect to throughput and concordance to STS. We found that the loss of information power was relatively low compared to the gain in speed and analytical standardization. The detection of point and length heteroplasmy turned out to be roughly comparable between the technologies with some individual differences related to the processes. We confirm that ESI-MS provides a valuable platform for analyzing mtDNA variation that can also be applied in the forensic context.

  14. Electrospray ionization mass spectrometric detection of low polar compounds by adding NaAuCl4.

    PubMed

    Moriwaki, Hiroshi

    2016-11-01

    Liquid chromatography electrospray ionization mass spectrometry (LC/ESI/MS) has been widely used for various analyses. However, it is difficult to use LC/ESI/MS for the analysis of low polar compounds, such as polycyclic aromatic hydrocarbons. It is well known that AuCl4(-) ion decomposes to AuCl3 by heating, and AuCl3 is a strong π-electrophilic Lewis acid. Low polar compounds (pyrene, benzo[a]pyrene, perylene, benzo[ghi]perylene, dibenzothiophene and p-dimethoxybenzene) were detected by ESI/MS in the positive ion mode by adding NaAuCl4 . The low polar compound interacts with AuCl3 formed at the ESI interface, and undergoes electron transfer to AuCl3 . The radical cation of the low polar compound was then detected by MS. In addition, the LC/ESI/MS determination of polycyclic aromatic hydrocarbons by the post-column addition of NaAuCl4 was studied. © 2016 The Authors Journal of Mass Spectrometry Published by John Wiley & Sons Ltd.

  15. Characterization and source apportionment of submicron aerosol with aerosol mass spectrometer during the PRIDE-PRD 2006 campaign

    NASA Astrophysics Data System (ADS)

    Xiao, R.; Takegawa, N.; Zheng, M.; Kondo, Y.; Miyazaki, Y.; Miyakawa, T.; Hu, M.; Shao, M.; Zeng, L.; Gong, Y.; Lu, K.; Deng, Z.; Zhao, Y.; Zhang, Y. H.

    2011-01-01

    Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the Southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8±8.4 μg m-3 and 13.5±8.7 μg m-3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva)~200 nm and the second mode occurred at Dva from 300-700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and

  16. Characterization and source apportionment of submicron aerosol with aerosol mass spectrometer during the PRIDE-PRD 2006 campaign

    NASA Astrophysics Data System (ADS)

    Xiao, R.; Takegawa, N.; Zheng, M.; Kondo, Y.; Miyazaki, Y.; Miyakawa, T.; Hu, M.; Shao, M.; Zeng, L.; Gong, Y.; Lu, K.; Deng, Z.; Zhao, Y.; Zhang, Y. H.

    2011-07-01

    Size-resolved chemical compositions of non-refractory submicron aerosol were measured using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS) at the rural site Back Garden (BG), located ~50 km northwest of Guangzhou in July 2006. This paper characterized the submicron aerosol particles of regional air pollution in Pearl River Delta (PRD) in the southern China. Organics and sulfate dominated the submicron aerosol compositions, with average mass concentrations of 11.8 ± 8.4 μg m-3 and 13.5 ± 8.7 μg m-3, respectively. Unlike other air masses, the air masses originated from Southeast-South and passing through the PRD urban areas exhibited distinct bimodal size distribution characteristics for both organics and sulfate: the first mode peaked at vacuum aerodynamic diameters (Dva) ∼200 nm and the second mode occurred at Dva from 300-700 nm. With the information from AMS, it was found from this study that the first mode of organics in PRD regional air masses was contributed by both secondary organic aerosol formation and combustion-related emissions, which is different from most findings in other urban areas (first mode of organics primarily from combustion-related emissions). The analysis of AMS mass spectra data by positive matrix factorization (PMF) model identified three sources of submicron organic aerosol including hydrocarbon-like organic aerosol (HOA), low volatility oxygenated organic aerosol (LV-OOA) and semi-volatile oxygenated organic aerosol (SV-OOA). The strong correlation between HOA and EC indicated primary combustion emissions as the major source of HOA while a close correlation between SV-OOA and semi-volatile secondary species nitrate as well as between LV-OOA and nonvolatile secondary species sulfate suggested secondary aerosol formation as the major source of SV-OOA and LV-OOA at the BG site. However, LV-OOA was more aged than SV-OOA as its spectra was highly correlated with the reference spectra of fulvic acid, an indicator of aged and

  17. Fragment formula calculator (FFC): determination of chemical formulas for fragment ions in mass spectrometric data.

    PubMed

    Wegner, André; Weindl, Daniel; Jäger, Christian; Sapcariu, Sean C; Dong, Xiangyi; Stephanopoulos, Gregory; Hiller, Karsten

    2014-02-18

    The accurate determination of mass isotopomer distributions (MID) is of great significance for stable isotope-labeling experiments. Most commonly, MIDs are derived from gas chromatography/electron ionization mass spectrometry (GC/EI-MS) measurements. The analysis of fragment ions formed during EI, which contain only specific parts of the original molecule can provide valuable information on the positional distribution of the label. The chemical formula of a fragment ion is usually applied to derive the correction matrix for accurate MID calculation. Hence, the correct assignment of chemical formulas to fragment ions is of crucial importance for correct MIDs. Moreover, the positional distribution of stable isotopes within a fragment ion is of high interest for stable isotope-assisted metabolomics techniques. For example, (13)C-metabolic flux analyses ((13)C-MFA) are dependent on the exact knowledge of the number and position of retained carbon atoms of the unfragmented molecule. Fragment ions containing different carbon atoms are of special interest, since they can carry different flux information. However, the process of mass spectral fragmentation is complex, and identifying the substructures and chemical formulas for these fragment ions is nontrivial. For that reason, we developed an algorithm, based on a systematic bond cleavage, to determine chemical formulas and retained atoms for EI derived fragment ions. Here, we present the fragment formula calculator (FFC) algorithm that can calculate chemical formulas for fragment ions where the chemical bonding (e.g., Lewis structures) of the intact molecule is known. The proposed algorithm is able to cope with general molecular rearrangement reactions occurring during EI in GC/MS measurements. The FFC algorithm is able to integrate stable isotope labeling experiments into the analysis and can automatically exclude candidate formulas that do not fit the observed labeling patterns.1 We applied the FFC algorithm to create

  18. Comparative Analysis of Volatile Defensive Secretions of Three Species of Pyrrhocoridae (Insecta: Heteroptera) by Gas Chromatography-Mass Spectrometric Method

    PubMed Central

    Krajicek, Jan; Havlikova, Martina; Bursova, Miroslava; Ston, Martin; Cabala, Radomir; Exnerova, Alice; Stys, Pavel; Bosakova, Zuzana

    2016-01-01

    The true bugs (Hemiptera: Heteroptera) have evolved a system of well-developed scent glands that produce diverse and frequently strongly odorous compounds that act mainly as chemical protection against predators. A new method of non-lethal sampling with subsequent separation using gas chromatography with mass spectrometric detection was proposed for analysis of these volatile defensive secretions. Separation was performed on Rtx-200 column containing fluorinated polysiloxane stationary phase. Various mechanical irritation methods (ultrasonics, shaking, pressing bugs with plunger of syringe) were tested for secretion sampling with a special focus on non-lethal irritation. The preconcentration step was performed by sorption on solid phase microextraction (SPME) fibers with different polarity. For optimization of sampling procedure, Pyrrhocoris apterus was selected. The entire multi-parameter optimization procedure of secretion sampling was performed using response surface methodology. The irritation of bugs by pressing them with a plunger of syringe was shown to be the most suitable. The developed method was applied to analysis of secretions produced by adult males and females of Pyrrhocoris apterus, Pyrrhocoris tibialis and Scantius aegyptius (all Heteroptera: Pyrrhocoridae). The chemical composition of secretion, particularly that of alcohols, aldehydes and esters, is species-specific in all three pyrrhocorid species studied. The sexual dimorphism in occurrence of particular compounds is largely limited to alcohols and suggests their epigamic intraspecific function. The phenetic overall similarities in composition of secretion do not reflect either relationship of species or similarities in antipredatory color pattern. The similarities of secretions may be linked with antipredatory strategies. The proposed method requires only a few individuals which remain alive after the procedure. Thus secretions of a number of species including even the rare ones can be

  19. Development and validation of a liquid chromatography-tandem mass spectrometric assay for quantitative analyses of triptans in hair.

    PubMed

    Vandelli, Daniele; Palazzoli, Federica; Verri, Patrizia; Rustichelli, Cecilia; Marchesi, Filippo; Ferrari, Anna; Baraldi, Carlo; Giuliani, Enrico; Licata, Manuela; Silingardi, Enrico

    2016-04-01

    Triptans are specific drugs widely used for acute treatment of migraine, being selective 5HT1B/1D receptor agonists. A proper assumption of triptans is very important for an effective treatment; nevertheless patients often underuse, misuse, overuse or use triptans inconsistently, i.e., not following the prescribed therapy. Drug analysis in hair can represent a powerful tool for monitoring the compliance of the patient to the therapy, since it can greatly increase the time-window of detection compared to analyses in biological fluids, such as plasma or urine. In the present study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method has been developed and validated for the quantitative analysis in human hair of five triptans commonly prescribed in Italy: almotriptan (AL), eletriptan (EP), rizatriptan (RIZ), sumatriptan (SUM) and zolmitriptan (ZP). Hair samples were decontaminated and incubated overnight in diluted hydrochloric acid; the extracts were purified by mixed-mode SPE cartridges and analyzed by LC-MS/MS under gradient elution in positive multiple reaction monitoring (MRM) mode. The procedure was fully validated in terms of selectivity, linearity, limit of detection (LOD) and lower limit of quantitation (LLOQ), accuracy, precision, carry-over, recovery, matrix effect and dilution integrity. The method was linear in the range 10-1000pg/mg hair, with R(2) values of at least 0.990; the validated LLOQ values were in the range 5-7pg/mg hair. The method offered satisfactory precision (RSD <10%), accuracy (90-110%) and recovery (>85%) values. The validated procedure was applied on 147 authentic hair samples from subjects being treated in the Headache Centre of Modena University Hospital in order to verify the possibility of monitoring the corresponding hair levels for the taken triptans.

  20. A carboxy-terminal affinity tag for the purification and mass spectrometric characterization of integral membrane proteins.

    PubMed

    Wong, Julie P; Reboul, Emmanuelle; Molday, Robert S; Kast, Juergen

    2009-05-01

    G-protein-coupled receptors (GPCRs) and other structurally and functionally related membrane proteins represent particularly attractive targets for drug discovery. Integral membrane proteins are often difficult to purify from native contexts, and lack of sufficient quantities hampers subsequent structural and functional proteomic studies. We describe here an optimized enrichment strategy involving a membrane protein-compatible 1D4 affinity tag that is derived from the carboxy-terminal nine amino residues of bovine rhodopsin, and its corresponding tag-specific, high-affinity monoclonal antibody. When two GPCRs as well as two related ATP binding cassette (ABC) transporters are expressed in their functional forms in human cell lines, we have shown that a single detergent and wash condition can be employed for the purification of all said membrane proteins. Subsequent in-gel digestion with trypsin and mass spectrometric peptide analysis resulted in high sequence coverage for the ABC transporters ABCA1-1D4 and ABCA4-1D4. In contrast, digestion by various enzymatic combinations was necessary to obtain the best sequence coverage for affinity-enriched GPCRs CXCR4-1D4 and CCR5-1D4 as compared against other entries in an annotated spectrum library. Furthermore, specific enzyme combinations were necessary to produce suitable peptides for deducing N-glycosylation sites on CXCR4. Our results demonstrate that the 1D4-tag enrichment strategy is a versatile tool for the characterization of integral membrane proteins that can be employed for functional proteomic studies.

  1. High-resolution mass spectrometric identification and quantification of glucocorticoid compounds in various wastewaters in the Netherlands.

    PubMed

    Schriks, Merijn; van Leerdam, Jan A; van der Linden, Sander C; van der Burg, Bart; van Wezel, Annemarie P; de Voogt, Pim

    2010-06-15

    In the past two decades much research effort has focused on the occurrence, effects, and risks of estrogenic compounds. However, increasing emissions of new emerging compounds may also affect the action of hormonal pathways other than the estrogenic hormonal axis. Recently, a suite of novel CALUX bioassays has become available that enables looking further than estrogenic effects only. By employing these bioassays, we recently showed high glucocorticogenic activity in wastewaters collected at various sites in The Netherlands. However, since bioassays provide an integrated biological response, the identity of the responsible biological compounds remained unknown. Therefore, our current objective was to elucidate the chemical composition of the wastewater extracts used in our previous study by means of LC-high-resolution Orbitrap MS/MS and to determine if the compounds quantified could account for the observed glucocorticoid responsive (GR) CALUX bioassay response. The mass spectrometric analysis revealed the presence of various glucocorticoids in the range of 13-1900 ng/L. In extracts of hospital wastewater-collected prior to sewage treatment-several glucocorticoids were identified (cortisol 275-301 ng/L, cortisone 381-472 ng/L, prednisone 117-545 ng/L, prednisolone 315-1918 ng/L, and triamcinolone acetonide 14-41 ng/L) which are used to treat a great number of human pathologies. A potency balance calculation based on the instrumental analyses and relative potencies (REPs) of the individual glucocorticoids supports the conclusion that triamcinolone acetonide (REP = 1.3), dexamethasone (REP = 1), and prednisolone (REP = 0.2) are the main contributors to the glucocorticogenic activity in the investigated wastewater extracts. The action of these compounds is concentration additive and the overall glucocorticogenic activity can be explained to a fairly large extent by their contribution.

  2. Tandem capillary column gas chromatography-mass spectrometric determination of the organophosphonate nerve agent surrogate dimethyl methylphosphonate in gaseous phase.

    PubMed

    McDaniel, Les N; Romero, Nicholas A; Boyd, Jonathan; Coimbatore, Gopal; Cobb, George P

    2010-06-15

    A procedure based on capillary column gas chromatographic-mass spectrometric (GC-MS) confirmation was developed for the verification of the ubiquitous and versatile chemical and nerve agent simulant, dimethyl methyl phosphonate (DMMP; CAS# 756-79-6), from gaseous samples. This method was developed to verify low nanogram DMMP concentrations during testing of a nerve agent detection system. Standard solutions of 1, 5, 10, 50, 100, 500, and 1000ng/ml DMMP in acetonitrile were employed. Through 15 calibration curves using the 5 lowest concentrations, coefficient of determination (r(2)) values showed a mean of 0.998 (0.992-1.000). An additional 15 calibration curves likewise containing 5 concentrations of DMMP spanning 3 orders of magnitude (1, 50, 100, 500, and 1000ng/ml) yielded a mean r(2) of 0.997 (0.991-1.000). Sixty-five nitrogen diluted gaseous samples varying from 1.0 to 10.0microl in volume were analyzed and concentrations of DMMP ranging from 1 to 1000ng/ml were confirmed. An additional 35 vapor samples in UHP N(2) ranging in DMMP concentration from 5.8microg/m(3) to 1.0mg/m(3) were analyzed by increasing sample volume range to between 10.0 and 100microl. For gaseous samples with volumes>1.0microl, the lowest concentration observed was 5.8microg/m(3). The method detection limit (Appendix B of Title 40 CFR, United States) for 1.0microl autoinjected standards in acetonitrile was determined to be 0.331ng/ml. Method precision for 15 independently analyzed standards of 25ng/ml had a relative standard deviation of 1.168. This method demonstrated high linearity across a wide range of concentrations, as well as excellent sensitivity and repeatability, and proved applicable to other lower alkyl-phosphonates.

  3. Gas chromatographic/mass spectrometric analysis of morphine and codeine in human urine of poppy seed eaters.

    PubMed

    elSohly, H N; Stanford, D F; Jones, A B; elSohly, M A; Snyder, H; Pedersen, C

    1988-03-01

    In this study, poppy seeds were examined for a natural constituent that might serve as a maker for the seeds' ingestion as opposed to opiate abuse. Thebaine was selected as possible marker, since it was found to be a component of all poppy seeds examined and was not a natural component of different heroin samples. During the course of this investigation, a new extraction and cleanup procedure was developed for the gas chromatographic/nitrogen phosphorus detection (GC/NPD) and gas chromatographic/mass spectrometric (GC/MS) analysis of morphine and codeine in urine. A linear response, over a concentration range of 25 to 600 ng/mL, was obtained for codeine and morphine (r = 0.9982 and 0.9947, respectively). The minimum detectable level (LOD) and limit of quantitation (LOQ) for morphine were 10 and 30 ng/mL, respectively; whereas LOD and LOQ for codeine were 2 and 8 ng/mL, respectively. The coefficients of variance (CV, n = 6) for morphine and codeine analyses at the 100-ng/mL level were 13.3 and 4.6%, respectively. This procedure was used for the analysis of urine samples from five poppy seed eaters who each ingested 200 g of poppy seed cake. Results indicated that significant amounts of morphine and codeine are excreted in urine and that in all subjects, at least at one point in time, the apparent morphine concentration as determined by radioimmunoassay (RIA) analysis exceeded the cutoff value (300 ng/mL) established for screening. Thebaine was not detected in urine specimens collected following poppy seeds ingestion and thus could not be used as a marker.

  4. Profiling of Piper betle Linn. cultivars by direct analysis in real time mass spectrometric technique.

    PubMed

    Bajpai, Vikas; Sharma, Deepty; Kumar, Brijesh; Madhusudanan, K P

    2010-12-01

    Piper betle Linn. is a traditional plant associated with the Asian and southeast Asian cultures. Its use is also recorded in folk medicines in these regions. Several of its medicinal properties have recently been proven. Phytochemical analysis showed the presence of mainly terpenes and phenols in betel leaves. These constituents vary in the different cultivars of Piper betle. In this paper we have attempted to profile eight locally available betel cultivars using the recently developed mass spectral ionization technique of direct analysis in real time (DART). Principal component analysis has also been employed to analyze the DART MS data of these betel cultivars. The results show that the cultivars of Piper betle could be differentiated using DART MS data.

  5. Novel mass spectrometric instrument for gaseous and particulate characterization and monitoring

    NASA Astrophysics Data System (ADS)

    Coggiola, M. J.; Becker, C. H.; Witham, C. L.

    1994-10-01

    An instrument is being developed that will be capable of providing real-time (less than 1 minute), quantitative, chemical analysis of gaseous and particulate pollutants generated from DOE waste cleanup activities. The instrument can detect and identify volatile organic compounds, polynuclear aromatic hydrocarbons, heavy metals, and transuranic species released during waste cleanup. It consists of an isokinetic sampler operable up to 500 K and wide flow rate range, a high- to low-pressure transition and sampling region separating particles from vapors for separate analysis, two small mass spectrometers (one for organic analysis by field ionization and one for particulate analysis by thermal pyrolysis and electron-impact ionization), and a powerful PC for control/data acquisition. Initially, the instrument will used with the K-1435 Toxic Substances Control Act (TSCA) incinerator at K-25; other applications are also possible, e.g., vitrification monitoring, storage tank offgassing analysis, etc. It will be easily transportable.

  6. Mass spectrometric identification of cyclic polysulfides in sediment of the Eastern Gulf of Finland. I.

    PubMed

    Khoroshko, Larisa O; Takhistov, Viatcheslav V; Petrova, Varvara N; Viktorovskii, Igor V; Lahtiperä, Mirja; Paasivirta, Jaakko

    2004-01-01

    Structures of six cyclic polysulfides, previously unknown as organic environmental pollutants, were analyzed from a sediment sample from the Eastern Gulf of Finland. The determinations were done by gas chromatography connected to mass spectrometry. High resolution (HRMS) measurements of the isotopic composition of four compounds could be done to confirm their molecular formulae. Total low resolution (LRMS) spectra were used to elucidate structures of all six compounds by thermochemical approach, application of fragmentation rules and by ICLU simulation of the spectra. The compounds were deduced to be (in the order of GC- retention) 1,2,4-trithiacycloheptane, tetrathiacyclopentane, 1,2,4,5-tetrathia-cyclohexane, 1,2,3,4- tetrathiacycloheptane, 1,2,3,4-tetrathiacyclohexane and 1,2,4,6-tetrathiacyclooctane.

  7. Oxidation of Carbon Supports at Fuel Cell Cathodes: Differential Electrochemical Mass Spectrometric Study

    NASA Astrophysics Data System (ADS)

    Li, Ming-fang; Tao, Qian; Liao, Ling-wen; Xu, Jie; Cai, Jun; Chen, Yan-xia

    2010-08-01

    The effects of O2 and the supported Pt nano-particles on the mechanisms and kinetics of the carbon support corrosion are investigated by monitoring the CO2 production using differential electrochemical mass spectrometry in a dual-thin layer flow cell. Carbon can be oxidized in different distinct potential regimes; O2 accelerates carbon oxidation, the rates of CO2 production from carbon oxidation in O2 saturated solution are two times of that in N2 saturated solution at the same potential; Pt can catalyze the carbon oxidation, with supported Pt nanoparticles, the overpotential for carbon oxidation is much smaller than that without loading in the carbon electrode. The mechanism for the enhanced carbon oxidation by Pt and O2 are discussed.

  8. [MALDI-TOF mass spectrometric identification of novel intercellular space peptides].

    PubMed

    Il'ina, A P; Kulikova, O G; Mal'tsev, D I; Krasnov, M S; Rybakova, E Iu; Skripnikova, V S; Kuznetsova, E S; Buriak, A K; Iamskova, V P; Iamskov, I A

    2011-01-01

    We performed the matrix-assisted laser desorption/ionisation, time-of-flight mass spectrometry (MALDI-TOF) analysis of the peptides entering into the composition of not yet explored bioregulators derived from the extracellular matrix of the tissues of the various organs of the mammals, and also plants and fungi. The study included 15 different mammalian tissues, 13 species of plants, and 2 species of fungi. Exploring the bioregulators derived from eye tissues, we demonstrated that their composition includes peptide components with the same values of the molecular weight. The composition of the bioregulators derived from the tissues of various organs of mammals or different species of plants and fungi includes the peptides with different values of molecular weight. Obtained data indicate the growing evidence of the assumptions about the major function of the bioregulators of this group--their involvement in the regulation of tissue-organ homeostasis in the biological systems.

  9. Gas chromatography - mass spectrometric analysis of four polluted river waters for phenolic and organic compounds.

    PubMed

    Nomani, A A; Ajmal, M; Ahmad, S

    1996-03-01

    Forty-four water samples from eleven sampling points were collected from four highly polluted rivers of northern India once in each four seasons during 1988-1989. The samples were analyzed for phenol, chlorophenols, a few bromophenols and other organics. Phenol was found to be absent in all the analyzed samples. Trichlorophenol and pentachlorophenol were frequently detected. Comparatively, the Ganges river was most polluted at Kannauj followed by Narora, Kachala and Fatehgarh. Maximum phenols were found at Mathura downstream of the Yamuna river followed by Mathura upstream, Okhla, ITO and none at Wazirabad. No phenols were detected in the water of the rivers Hindon and Kali at Ghaziabad and Aligarh, respectively. Some other organic pollutants were also identified by their mass spectra and supported by data from the computerized library, but, not quantified.

  10. Advances in sample preparation in electromigration, chromatographic and mass spectrometric separation methods.

    PubMed

    Gilar, M; Bouvier, E S; Compton, B J

    2001-02-16

    The quality of sample preparation is a key factor in determining the success of analysis. While analysis of pharmaceutically important compounds in biological matrixes has driven forward the development of sample clean-up procedures in last 20 years, today's chemists face an additional challenge: sample preparation and analysis of complex biochemical samples for characterization of genotypic or phenotypic information contained in DNA and proteins. This review focuses on various sample pretreatment methods designed to meet the requirements for the analysis of biopolymers and small drugs in complex matrices. We discuss the advances in development of solid-phase extraction (SPE) sorbents, on-line SPE, membrane-based sample preparation, and sample clean-up of biopolymers prior to their analysis by mass spectrometry.

  11. Mass Spectrometric Analysis of Spatio-Temporal Dynamics of Crustacean Neuropeptides

    PubMed Central

    OuYang, Chuanzi; Liang, Zhidan; Li, Lingjun

    2014-01-01

    Neuropeptides represent one of the largest classes of signaling molecules used by nervous systems to regulate a wide range of physiological processes. Over the past several years, mass spectrometry (MS)-based strategies have revolutionized the discovery of neuropeptides in numerous model organisms, especially in decapod crustaceans. Here, we focus our discussion on recent advances in the use of MS-based techniques to map neuropeptides in spatial domain and monitoring their dynamic changes in temporal domain. These MS-enabled investigations provide valuable information about the distribution, secretion and potential function of neuropeptides with high molecular specificity and sensitivity. In situ MS imaging and in vivo microdialysis are highlighted as key technologies for probing spatio-temporal dynamics of neuropeptides in the crustacean nervous system. This review summarizes the latest advancement in MS-based methodologies for neuropeptide analysis including typical workflow and sample preparation strategies as well as major neuropeptide families discovered in decapod crustaceans. PMID:25448012

  12. Gas chromatographic-mass spectrometric determination of adipate-based polymeric plasticizers in foods.

    PubMed

    Castle, L; Mercer, A J; Gilbert, J

    1988-01-01

    A method for the quantitative determination of adipate-based polymeric plasticizers in foods is described. The procedure involves extraction from the food and transmethylation of the polymeric plasticizer to form dimethyladipate (DMA). The derivative is cleaned up by size-exclusion chromatography and determined by capillary gas chromatography-mass spectrometry with selected ion monitoring. The use of a deuterated internal standard at the extraction stage enables quantitation by stable isotope dilution. A detection limit of 0.1 mg/kg of the polymeric plasticizer in foods and a relative standard deviation of 4% have been achieved routinely. The method has been applied successfully to the analysis of cheese, sandwiches, meat, biscuits, and cake that have been in contact with polymeric plasticized poly(vinyl chloride) films.

  13. Letter: Mass spectrometric approach of high pH- and copper-induced glutathione oxidation.

    PubMed

    Drochioiu, Gabi; Ion, Laura; Ciobanu, Catalina; Habasescu, Laura; Mangalagiu, Ionel

    2013-01-01

    The interaction between copper ions and gamma-L-glutamyl-L-cysteinyl-glycine [glutathione (GSH)] molecules may lead to the formation of the physiologically occurring Cu[I)-[GSH]2 and Cu(II)-GSSG complexes. Since glutathione depletion in neurons and aberrant copper metabolism have been implicated in several neurodegenerative disorders, we studied here the interaction of GSH with copper ions (Cu2+) by electrospray ionization ion trap mass spectrometry (ESI-IT-MS). Besides, we extended this approach to pH in excess of 10 by adding ethanolamine to the solution being investigated. As a result, the ESI-IT-MS spectra revealed novel aspects regarding the speciation of copper-glutathione complex.

  14. Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis

    USGS Publications Warehouse

    Ball, J.W.; Bassett, R.L.

    2000-01-01

    A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less. (C) 2000 Elsevier Science B.V. All rights reserved.

  15. Real-time mass spectrometric study of the methanol crossover in a direct methanol fuel cell

    SciTech Connect

    Wang, J.T.; Wasmus, S.; Savinell, R.F.

    1996-04-01

    The products of methanol crossover through the acid-doped polybenzimidazole polymer electrolyte membrane (PBI PEM) to the cathode of a prototype direct methanol fuel cell (DMFC) were analyzed using multipurpose electrochemical mass spectrometry (MPEMS) coupled to the cathode exhaust gas outlet. It was found that the methanol crossing over reacts almost quantitatively to CO{sub 2} at the cathode with the platinum of the cathode acting as a heterogeneous catalyst. The cathode open-circuit potential is inversely proportional to the amount of CO{sub 2} formed. A poisoning effect on the oxygen reduction also was found. Methods for the estimation of the methanol crossover rate at operating fuel cells are suggested.

  16. Rapid on-membrane proteolytic cleavage for Edman sequencing and mass spectrometric identification of proteins.

    PubMed

    Pham, Victoria C; Henzel, William J; Lill, Jennie R

    2005-11-01

    A method for the rapid limited enzymatic cleavage of PVDF membrane-immobilized proteins is described. This method allows the fast characterization of PVDF blotted proteins by peptide mass fingerprinting (Henzel, W. J., Billeci, T. M., Stults, J. T., Wong, S. C., Grimley, C., Wantanabe, C., Proc. Natl. Acad. Sci. USA 1993, 90, 5011-5015), LC-MS/MS, or N-terminal sequencing and has been demonstrated on a range of proteins using a full complement of proteolytic enzymes. This technique allows the generation of proteolytic fragments between 5 and 60 min (depending on the enzyme employed), which is significantly faster than previously reported on-membrane digestion methods. To date, this on-membrane rapid digestion protocol has aided in the identification and confirmation of mutation sites in over 200 recombinant proteins.

  17. Gas chromatographic-mass spectrometric method for polycyclic aromatic hydrocarbon analysis in plant biota.

    PubMed

    Meudec, A; Dussauze, J; Jourdin, M; Deslandes, E; Poupart, N

    2006-03-10

    Using gas chromatography-mass spectrometry, a new method was developed for the identification and the quantification of polycyclic aromatic hydrocarbons (PAHs) in plants. This method was particularly optimised for PAH analyses in marine plants such as the halophytic species, Salicornia fragilis Ball et Tutin. The saponification of samples and their clean up by Florisil solid-phase extraction succeeded in eliminating pigments and natural compounds, which may interfere with GC-MS analysis. Moreover, a good recovery of the PAHs studied was obtained with percentages ranging from 88 to 116%. Application to the determination of PAH in a wide range of coastal halophytic plants is presented and validated the efficiency, the accuracy and the reproducibility of this method.

  18. Sensitive and specific liquid chromatographic-tandem mass spectrometric assay for barnidipine in human plasma.

    PubMed

    Pawula, M; Watson, D; Teramura, T; Watanabe, T; Higuchi, S; Cheng, K N

    1998-11-20

    A sensitive and specific LC-MS-MS assay has been developed and validated for barnidipine (1-benzyl-3-pyrrolidinyl)methyl-2,6-dimethyl-4(m-nitrophenyl)-1,4-dihydr opyridine-3,5-dicarboxylate). The assay involves a simple and rapid solid-phase extraction procedure. Sample analysis was on a Spherisorb S3ODS2 100 mmX2 mm I.D. column, with a Finnigan TSQ 7000 mass spectrometer, using an electrospray interface and selective reaction monitoring (SRM). The intra- and inter-day precision and accuracy, determined as the coefficient of variation and relative error, respectively, were 11.8% or less. The limit of quantitation was 0.03 ng/ml, and the calibration was linear between 0.03 and 3.0 ng/ml. The method has been used successfully for the measurement of over two thousand human plasma samples from pharmacokinetic clinical trials.

  19. Mass Spectrometric Evidence of Malonaldehyde and 4-Hydroxynonenal Adductions to Radical-Scavenging Soy Peptides

    PubMed Central

    Zhao, Jing; Chen, Jing; Zhu, Haining; Xiong, Youling L.

    2012-01-01

    Antioxidative peptides in food systems are potential targets of lipid oxidation-generated reactive aldehydes, such as malonaldehyde (MDA) and 4-hydroxynonenal (HNE). In this study, covalent modifications on radical-scavenging peptides prepared from soy protein hydrolysate by MDA and HNE were characterized by liquid chromatography–electrospray ionization-mass spectrometry (LC-ESI-MS/MS). MS/MS analyses detected the formation of Schiff base type adducts of MDA on the side chain groups of lysine, histidine, arginine, glutamine, and asparagine residues as well as the N-termini of peptides. MDA also formed a fluorescent product with lysine residues. HNE adducted on lysine residues through Schiff base formation and on histidine, arginine, glutamine, and asparagine residues mainly through Michael addition. In spite of the extensive MDA modification, peptide cross-linking by this potential mechanism was undetectable. PMID:22946674

  20. Honeybee venom proteome profile of queens and winter bees as determined by a mass spectrometric approach.

    PubMed

    Danneels, Ellen L; Van Vaerenbergh, Matthias; Debyser, Griet; Devreese, Bart; de Graaf, Dirk C

    2015-10-30

    Venoms of invertebrates contain an enormous diversity of proteins, peptides, and other classes of substances. Insect venoms are characterized by a large interspecific variation resulting in extended lists of venom compounds. The venom composition of several hymenopterans also shows different intraspecific variation. For instance, venom from different honeybee castes, more specifically queens and workers, shows quantitative and qualitative variation, while the environment, like seasonal changes, also proves to be an important factor. The present study aimed at an in-depth analysis of the intraspecific variation in the honeybee venom proteome. In summer workers, the recent list of venom proteins resulted from merging combinatorial peptide ligand library sample pretreatment and targeted tandem mass spectrometry realized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS/MS). Now, the same technique was used to determine the venom proteome of queens and winter bees, enabling us to compare it with that of summer bees. In total, 34 putative venom toxins were found, of which two were never described in honeybee venoms before. Venom from winter workers did not contain toxins that were not present in queens or summer workers, while winter worker venom lacked the allergen Api m 12, also known as vitellogenin. Venom from queen bees, on the other hand, was lacking six of the 34 venom toxins compared to worker bees, while it contained two new venom toxins, in particularly serine proteinase stubble and antithrombin-III. Although people are hardly stung by honeybees during winter or by queen bees, these newly identified toxins should be taken into account in the characterization of a putative allergic response against Apis mellifera stings.

  1. Use of flow injection mass spectrometric fingerprinting and chemometrics for differentiation of three black cohosh species

    NASA Astrophysics Data System (ADS)

    Huang, Huilian; Sun, Jianghao; McCoy, Joe-Ann; Zhong, Haiyan; Fletcher, Edward J.; Harnly, James; Chen, Pei

    2015-03-01

    Flow injection mass spectrometry (FIMS) was used to provide chemical fingerprints of black cohosh (Actaea racemosa L.) in a manner of minutes by omitting the separation step. This method has proven to be a powerful tool for botanical authentication and in this study it was used to distinguish between three Actaea species prior to a more detailed chemical analysis using ultra high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Black cohosh has become increasingly popular as a dietary supplement in the United States for the treatment of symptoms related to menopause. However, it has been known to be adulterated with the Asian Actaea dahurica (Turcz. ex Fisch. & C.A.Mey.) Franch. species (syn. Cimicifuga dahurica (Turcz.) Maxim). Existing methods for identification of black cohosh and differentiation of Actaea species are usually lengthy, laborious, and lack robustness, often based on the comparison of a few pre-selected components. Chemical fingerprints were obtained for 77 black cohosh samples and their related species using FIMS in the negative ion mode. The analysis time for each sample was less than 2 min. All data were processed using principal component analysis (PCA). FIMS fingerprints could readily differentiate all three species. Representative samples from each of the three species were further examined using UHPLC-MS to provide detailed profiles of the chemical differences between the three species and were compared to the PCA loadings. This study demonstrates a simple, fast, and easy analytical method that can be used to differentiate A. racemosa, Actaea podocarpa, and A. dahurica.

  2. Expression, purification and mass spectrometric analysis of LIM mineralization protein-1 in human lung epithelial cells.

    PubMed

    Sangadala, Sreedhara; Titus, Louisa; Boden, Scott D

    2008-11-01

    LIM mineralization protein-1 (LMP-1) is a novel osteoinductive protein that has been cloned and shown to induce bone formation both in vitro and in vivo. Detection and evaluation of the possible presence of carbohydrate structures in LMP-1 is an important regulatory consideration for the therapeutic use of recombinantly expressed protein. The sequence of LMP-1 contains a highly conserved N-terminal PDZ domain and three C-terminal LIM domains. The sequence analysis of LMP-1 predicts two potential N-glycosylation sites and several O-glycosylation sites. Here, we report the cloning and overexpression of LMP-1 in human lung carcinoma (A549) cells. Even though our group already reported the sequence of LMP-1 cDNA, we undertook this work to clarify whether or not the overexpressed protein undergoes any glycosylation in vivo. The expressed full-length recombinant protein was purified and subjected to chemical analysis and internal sequencing. The absence of any hexosamines (N-acetyl glucosamine or N-acetyl galactosamine) in chemical composition analysis of LMP-1 protein revealed that there is little or no post-translational glycosylation of the LMP-1 polypeptide in lung carcinoma cells (A549). We performed in-gel trypsin digestion on purified LMP-1, and the resulting peptide digests were analyzed further using matrix-assisted laser desorption and ionization mass spectrometry for peptide mass finger printing, which produced several exact matches with the corresponding LMP-1 peptides. Separation by high performance liquid chromatography and purification of the desired peptides followed by N-terminal sequencing resulted in many exact LMP-1 matches for several purified peptides, thus establishing the identity of the purified protein as LMP-1.

  3. Honeybee Venom Proteome Profile of Queens and Winter Bees as Determined by a Mass Spectrometric Approach

    PubMed Central

    Danneels, Ellen L.; Van Vaerenbergh, Matthias; Debyser, Griet; Devreese, Bart; de Graaf, Dirk C.

    2015-01-01

    Venoms of invertebrates contain an enormous diversity of proteins, peptides, and other classes of substances. Insect venoms are characterized by a large interspecific variation resulting in extended lists of venom compounds. The venom composition of several hymenopterans also shows different intraspecific variation. For instance, venom from different honeybee castes, more specifically queens and workers, shows quantitative and qualitative variation, while the environment, like seasonal changes, also proves to be an important factor. The present study aimed at an in-depth analysis of the intraspecific variation in the honeybee venom proteome. In summer workers, the recent list of venom proteins resulted from merging combinatorial peptide ligand library sample pretreatment and targeted tandem mass spectrometry realized with a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS/MS). Now, the same technique was used to determine the venom proteome of queens and winter bees, enabling us to compare it with that of summer bees. In total, 34 putative venom toxins were found, of which two were never described in honeybee venoms before. Venom from winter workers did not contain toxins that were not present in queens or summer workers, while winter worker venom lacked the allergen Api m 12, also known as vitellogenin. Venom from queen bees, on the other hand, was lacking six of the 34 venom toxins compared to worker bees, while it contained two new venom toxins, in particularly serine proteinase stubble and antithrombin-III. Although people are hardly stung by honeybees during winter or by queen bees, these newly identified toxins should be taken into account in the characterization of a putative allergic response against Apis mellifera stings. PMID:26529016

  4. Renewal of an old European Pharmacopoeia method for Terazosin using modeling with mass spectrometric peak tracking.

    PubMed

    Kormány, Róbert; Molnár, Imre; Fekete, Jenő

    2017-02-20

    An older method for terazosin was reworked in order to reduce the analysis time from 90min (2×45min) to below 5min. The method in European Pharmacopoeia (Ph.Eur.) investigates the specified impurities separately. The reason of the different methods is that the retention of two impurities is not adequate in reversed phase, not even with 100% water. Therefore ion-pair-chromatography has to be applied and since that two impurities absorb at low UV-wavelength they had to be analyzed by different method than the other specified impurities. In our new method we could improve the retention with pH elevation using a new type of stationary phases available for high pH applications. Also a detection wavelength could be selected that is appropriate for the detection and quantification of all impurities. The method development is the bottleneck of liquid chromatography even today, when more and more fast chromatographic systems are used. Expert knowledge with intelligent programs is available to reduce the time of method development and offer extra information about the robustness of the separation. Design of Experiments (DoE) for simultaneous optimization of gradient time (tG), temperature (T) and ternary eluent composition (tC) requires 12 experiments. A good alternative way to identify a certain peak in different chromatograms is the molecular mass of the compound, due to its high specificity. Liquid Chromatography-Mass Spectrometry (LC-MS) is now a routine technique and increasingly available in laboratories. In our experiment for the resolution- and retention modeling the DryLab4 method development software (Version 4.2) was used. In recent versions of the software the use of (m/z)-MS-data is possible along the UV-peak-area-tracking technology. The modelled and measured chromatograms showed excellent correlations. The average retention time deviations were ca. 0.5s and there was no difference between the predicted and measured Rs,crit -values.

  5. Mass spectrometric approaches for the identification of anthracycline analogs produced by actinobacteria.

    PubMed

    Bauermeister, Anelize; Zucchi, Tiago Domingues; Moraes, Luiz Alberto Beraldo

    2016-06-01

    Anthracyclines are a well-known chemical class produced by actinobacteria used effectively in cancer treatment; however, these compounds are usually produced in few amounts because of being toxic against their producers. In this work, we successfully explored the mass spectrometry versatility to detect 18 anthracyclines in microbial crude extract. From collision-induced dissociation and nuclear magnetic resonance spectra, we proposed structures for five new and identified three more anthracyclines already described in the literature, nocardicyclins A and B and nothramicin. One new compound 8 (4-[4-(dimethylamino)-5-hydroxy-4,6-dimethyloxan-2-yl]oxy-2,5,7,12-tetrahydroxy-3,10-dimethoxy-2-methyl-3,4-dihydrotetracene-1,6,11-trione) was isolated and had its structure confirmed by (1) H nuclear magnetic resonance. The anthracyclines identified in this work show an interesting aminoglycoside, poorly found in natural products, 3-methyl-rhodosamine and derivatives. This fact encouraged to develop a focused method to identify compounds with aminoglycosides (rhodosamine, m/z 158; 3-methyl-rhodosamine, m/z 172; 4'-O-acethyl-3-C-methyl-rhodosamine, m/z 214). This method allowed the detection of four more anthracyclines. This focused method can also be applied in the search of these aminoglycosides in other microbial crude extracts. Additionally, it was observed that nocardicyclin A, nothramicin and compound 8 were able to interact to DNA through a DNA-binding study by mass spectrometry, showing its potential as anticancer drugs. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Systematic analysis of glycerol: colourimetric screening and gas chromatography-mass spectrometric confirmation.

    PubMed

    Sardela, Vinícius F; Scalco, Fernanda B; Cavalcante, Karina M; Simoni, Ruth E; Silva, Deyvison R; Pereira, Henrique Marcelo G; de Oliveira, Maria Lúcia L Costa; Aquino Neto, Francisco R

    2015-10-01

    Glycerol is a naturally occurring polyol in the human body, essential for several metabolic processes. It is widely used in the food, pharmaceutical, and medical industries and in clinical practice as a plasma volume expander (PVE). Athletes, however, may use glycerol to mask the presence of forbidden substances or to enhance performance, inclusively through hyperhydration achieved by glycerol ingestion with added fluid. These practices are considered doping, and are prohibited by the World Anti-Doping Agency (WADA). Therefore, glycerol was introduced in the prohibited list. Doping through glycerol ingestion can readily be identified by detection of elevated glycerol concentrations in urine. In this paper, a protocol for the fast detection of glycerol in urine is proposed. It consists of a previous visual colourimetric screening, followed by a quantitative/qualitative confirmation analysis by mass spectrometry. The screening procedure involves a reaction in which polyhydric alcohols are oxidized by periodate to formic acid and formaldehyde, which is detected by the addition of a fuchsin solution. For the subsequent qualitative/quantitative confirmation analysis, a gas chromatography-mass spectrometry based approach with a non-deuterated internal standard and a drying step of only 10 min is proposed. The linear correlation was demonstrated within WADA´s threshold range. The calculated RSD were 2.1% for within-day precision and 2.8% for between-day precision. The uncertainty estimation was calculated, and a value of 2.7% was obtained. The procedure may also be used for the analysis of other polyols in urine, as for example the PVE mannitol.

  7. Multi-centre evaluation of mass spectrometric identification of anaerobic bacteria using the VITEK® MS system.

    PubMed

    Garner, O; Mochon, A; Branda, J; Burnham, C-A; Bythrow, M; Ferraro, M; Ginocchio, C; Jennemann, R; Manji, R; Procop, G W; Richter, S; Rychert, J; Sercia, L; Westblade, L; Lewinski, M

    2014-04-01

    Accurate and timely identification of anaerobic bacteria is critical to successful treatment. Classic phenotypic methods for identification require long turnaround times and can exhibit poor species level identification. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an identification method that can provide rapid identification of anaerobes. We present a multi-centre study assessing the clinical performance of the VITEK(®) MS in the identification of anaerobic bacteria. Five different test sites analysed a collection of 651 unique anaerobic isolates comprising 11 different genera. Multiple species were included for several of the genera. Briefly, anaerobic isolates were applied directly to a well of a target plate. Matrix solution (α-cyano-4-hydroxycinnamic acid) was added and allowed to dry. Mass spectra results were generated with the VITEK(®) MS, and the comparative spectral analysis and organism identification were determined using the VITEK(®) MS database 2.0. Results were confirmed by 16S rRNA gene sequencing. Of the 651 isolates analysed, 91.2% (594/651) exhibited the correct species identification. An additional eight isolates were correctly identified to genus level, raising the rate of identification to 92.5%. Genus-level identification consisted of Actinomyces, Bacteroides and Prevotella species. Fusobacterium nucleatum, Actinomyces neuii and Bacteroides uniformis were notable for an increased percentage of no-identification results compared with the other anaerobes tested. VITEK(®) MS identification of clinically relevant anaerobes is highly accurate and represents a dramatic improvement over other phenotypic methods in accuracy and turnaround time.

  8. On the N2O correction used for mass spectrometric analysis of atmospheric CO2.

    PubMed

    Assonov, S S; Brenninkmeijer, C A M

    2006-01-01

    To obtain accurate values of delta(13)C(CO(2)) and delta(18)O(CO(2)) on environmental CO(2) by mass spectrometry, the raw isotope data must be corrected for the isobaric N(2)O contribution. This is one of the analytical problems limiting inter-laboratory delta(13)C(CO(2)) data consistency. The key parameter, the N(2)O relative ionisation efficiency (E(N2O)), cannot be determined with sufficient accuracy by direct measurements of pure N(2)O. The determination of (E(N2O)) by analyses on N(2)O--CO(2) mixtures of known isotope composition and mixing proportions has been recently suggested. In this work we propose a new method of N(2)O correction which uses the m/z 30 signal as a measure of the N(2)O/CO(2) ratio, so that determinations of (E(N2O)) and N(2)O content are not required. The method uses the fact that fragment-ion spectra of N(2)O and CO(2) are very specific. The formalism of the correction is considered. Various tests demonstrate that the new method is robust, stable and easy to implement in practice. The effective value (E(N2O)) (the key parameter for the new correction) has to be calibrated on known N(2)O--CO(2) mixtures by measuring (30)R signals only. The method accuracy we presently achieved is around 2.5% and any error which appears to come mostly from our N(2)O--CO(2) mixture preparation. Based on our tests and error considerations, the error of the proposed method that may be achieved is as low as +/-1.5% (relative to the correction magnitude). For tropospheric CO(2) this means +/-0.003 per thousand and +/-0.005 per thousand for delta(13)C(CO(2)) and delta(18)O(CO(2)), respectively. The proposed method may be valuable for small samples where no separate N(2)O determinations are available (e.g. ice core samples and CF-IRMS measurements) as well as for determination of (E(N2O)) and testing the 'traditional' N(2)O correction based on mass balance calculations.

  9. Metabolism of 4-hydroxyandrostenedione and 4-hydroxytestosterone: Mass spectrometric identification of urinary metabolites.

    PubMed

    Kohler, Maxie; Parr, Maria K; Opfermann, Georg; Thevis, Mario; Schlörer, Nils; Marner, Franz-Josef; Schänzer, Wilhelm

    2007-03-01

    4-Hydroxyandrost-4-ene-3,17-dione is a second generation, irreversible aromatase inhibitor and commonly used as anti breast cancer medication for postmenopausal women. 4-Hydroxytestosterone is advertised as anabolic steroid and does not have any therapeutic indication. Both substances are prohibited in sports by the World Anti-Doping Agency, and, due to a considerable increase of structurally related steroids with anabolic effects offered via the internet, the metabolism of two representative candidates was investigated. Excretion studies were conducted with oral applications of 100mg of 4-hydroxyandrostenedione or 200mg of 4-hydroxytestosterone to healthy male volunteers. Urine samples were analyzed for metabolic products using conventional gas chromatography-mass spectrometry approaches, and the identification of urinary metabolites was based on reference substances, which were synthesized and structurally characterized by nuclear magnetic resonance spectroscopy and high resolution/high accuracy mass spectrometry. Identified phase-I as well as phase-II metabolites were identical for both substances. Regarding phase-I metabolism 4-hydroxyandrostenedione (1) and its reduction products 3beta-hydroxy-5alpha-androstane-4,17-dione (2) and 3alpha-hydroxy-5beta-androstane-4,17-dione (3) were detected. Further reductive conversion led to all possible isomers of 3xi,4xi-dihydroxy-5xi-androstan-17-one (4, 6-11) except 3alpha,4alpha-dihydroxy-5beta-androstan-17-one (5). Out of the 17beta-hydroxylated analogs 4-hydroxytestosterone (18), 3beta,17beta-dihydroxy-5alpha-androstan-4-one (19), 3alpha,17beta-dihydroxy-5beta-androstan-4-one (20), 5alpha-androstane-3beta,4beta,17beta-triol (21), 5alpha-androstane-3alpha,4beta,17beta-triol (26) and 5alpha-androstane-3alpha,4alpha,17beta-triol (28) were identified in the post administration urine specimens. Furthermore 4-hydroxyandrosta-4,6-diene-3,17-dione (29) and 4-hydroxyandrosta-1,4-diene-3,17-dione (30) were determined as

  10. Online solid phase extraction and liquid chromatography-mass spectrometric determination of nucleoside drugs in plasma.

    PubMed

    Wang, Man; Ma, Ping; Xi, Xiaonan; Liu, Lei; Wen, Yabin; Liu, Kangning; Sun, Liang; Lu, Yaxin; Yin, Zheng

    2016-12-01

    The bioanalysis and especially the sample preparation of nucleoside drugs in complex media, such as human plasma, has been challenging due to the high polarity and high solubility of these drugs in water. Online solid phase extraction (SPE) offers significant advantages, such as automation and timesaving. Thus, several types of SPE columns have been developed for compounds with different polarities. In this study, SPE was applied to overcome the issue of sample pretreatment of nucleoside drugs in human plasma, with the final aim of establishing a robust analytical platform for drugs with similar structures. A simple, easy-to-use, and efficient method is described for the simultaneous determination of lamivudine, zidovudine, didanosine and emtricitabine in human plasma via online SPE and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Following a simple centrifugation step, a 10μL plasma sample was injected directly onto the HPLC system. The Oasis MCX cartridge was washed, and the analytes were removed by back-flushing directly onto the analytical column. The analytes were quantified using a triple-quadrupole tandem mass spectrometer in multiple-reaction monitoring mode. Similarly, with the development and application of a Bond Elut phenylboronic acid (PBA) SPE cartridge, a fully automated online SPE-HPLC-MS/MS method was established for the simultaneous determination of ribavirin and taribavirin in human plasma. Linear calibration curves were obtained over the range of 0.5-2000ngmL(-1), and the limit of quantification ranged from 0.5ngmL(-1) to 10ngmL(-1), which is sensitive enough for clinical drug monitoring. The intra- and inter-day precisions were in the range of 0.2-8.9%, and the trueness ranged between 88.9% and 113.1%. Excellent recoveries from plasma were achieved with a range between 86.7% and 105.1%. This procedure is easier to perform and requires less sample handling compared to methods previously described in the

  11. In-depth mass spectrometric mapping of the human vitreous proteome

    PubMed Central

    2013-01-01

    Mapping of proteins involved in normal eye functions is a prerequisite to identify pathological changes during eye disease processes. We therefore analysed the proteome of human vitreous by applying in-depth proteomic screening technologies. For ethical reasons human vitreous samples were obtained by vitrectomy from “surrogate normal patients” with epiretinal gliosis that is considered to constitute only negligible pathological vitreoretinal changes. We applied different protein prefractionation strategies including liquid phase isoelectric focussing, 1D SDS gel electrophoresis and a combination of both and compared the number of identified proteins obtained by the respective method. Liquid phase isoelectric focussing followed by SDS gel electrophoresis increased the number of identified proteins by a factor of five compared to the analysis of crude unseparated human vitreous. Depending on the prefractionation method proteins were subjected to trypsin digestion either in-gel or in solution and the resulting peptides were analysed on a UPLC system coupled online to an LTQ Orbitrap XL mass spectrometer. The obtained mass spectra were searched against the SwissProt database using the Mascot search engine. Bioinformatics tools were used to annotate known biological functions to the detected proteins. Following this strategy we examined the vitreous proteomes of three individuals and identified 1111 unique proteins. Besides structural, transport and binding proteins, we detected 261 proteins with known enzymatic activity, 51 proteases, 35 protease inhibitors, 35 members of complement and coagulation cascades, 15 peptide hormones, 5 growth factors, 11 cytokines, 47 receptors, 30 proteins of visual perception, 91 proteins involved in apoptosis regulation and 265 proteins with signalling activity. This highly complex mixture strikingly differs from the human plasma proteome. Thus human vitreous fluid seems to be a unique body fluid. 262 unique proteins were detected

  12. Urban increments of gaseous and aerosol pollutants and their sources using mobile aerosol mass spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Elser, Miriam; Bozzetti, Carlo; El-Haddad, Imad; Maasikmets, Marek; Teinemaa, Erik; Richter, Rene; Wolf, Robert; Slowik, Jay G.; Baltensperger, Urs; Prévôt, André S. H.

    2016-06-01

    Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero ≤ 2.5 µm) in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR)-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC) and several trace gases including carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA) constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF): hydrocarbon-like OA (HOA, from traffic emissions), biomass burning OA (BBOA, from biomass combustion), residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning), and oxygenated OA (OOA, related to secondary aerosol formation). OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded regional background

  13. Characterization of ice-nucleating bacteria using on-line electron impact ionization aerosol mass spectrometry.

    PubMed

    Wolf, R; Slowik, J G; Schaupp, C; Amato, P; Saathoff, H; Möhler, O; Prévôt, A S H; Baltensperger, U

    2015-04-01

    The mass spectral signatures of airborne bacteria were measured and analyzed in cloud simulation experiments at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) facility. Suspensions of cultured cells in pure water were sprayed into the aerosol and cloud chambers forming an aerosol which consisted of intact cells, cell fragments and residual particles from the agar medium in which the bacteria were cultured. The aerosol particles were analyzed with a high-resolution time-of-flight aerosol mass spectrometer equipped with a newly developed PM2.5 aerodynamic lens. Positive matrix factorization (PMF) using the multilinear engine (ME-2) source apportionment was applied to deconvolve the bacteria and agar mass spectral signatures. The bacteria mass fraction contributed between 75 and 95% depending on the aerosol generation, with the remaining mass attributed to agar. We present mass spectra of Pseudomonas syringae and Pseudomonas fluorescens bacteria typical for ice-nucleation active bacteria in the atmosphere to facilitate the distinction of airborne bacteria from other constituents in ambient aerosol, e.g. by PMF/ME-2 source apportionment analyses. Nitrogen-containing ions were the most salient feature of the bacteria mass spectra, and a combination of C4 H8 N(+) (m/z 70) and C5 H12 N(+) (m/z 86) may be used as marker ions.

  14. Ultrafast High-Resolution Mass Spectrometric Finger Pore Imaging in Latent Finger Prints

    NASA Astrophysics Data System (ADS)

    Elsner, Christian; Abel, Bernd

    2014-11-01

    Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record `three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high- spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals.

  15. Identification of aberrantly expressed glycans in gastric cancer by integrated lectin microarray and mass spectrometric analyses

    PubMed Central

    Li, Xiang; Guan, Feng; Li, Dongliang; Tan, Zengqi; Yang, Ganglong; Wu, Yanli; Huang, Zhaohui

    2016-01-01

    Cancer progression is usually associated with alterations of glycan expression patterns. Little is known regarding global glycomics in gastric cancer, the most common type of epithelial cancer. We integrated lectin microarray and mass spectrometry (MS) methods to profile glycan expression in three gastric cancer cell lines (SGC-7901, HGC-27, and MGC-803) and one normal gastric epithelial cell line (GES-1). Significantly altered glycans were confirmed by lectin staining and MALDI-TOF/TOF-MS. The three cancer cell lines showed increased levels of core-fucosylated N-glycans, GalNAcα-Ser/Thr (Tn antigen), and Sia2-6Galβ1-4GlcNAc N-glycans, but reduced levels of biantennary N-glycans, Galβ1-3GalNAcα-Ser/Thr (T antigen), and (GlcNAc)n N-glycans. Lectin histochemistry was used to validate aberrant expression of four representative glycans (core-fucosylation, Sia2-6Galβ1-4GlcNAc, biantennary N-glycans, T antigen, recognized respectively by lectins LCA, SNA, PHA-E+L, and ACA) in clinical gastric cancer samples. Lower binding capacity for ACA was correlated with significantly poorer patient prognosis. Our findings indicate for the first time that glycans recognized by LCA, ACA, and PHA-E+L are aberrantly expressed in gastric cancer, and suggest that ACA is a potential prognostic factor for gastric cancer. PMID:27895315

  16. Mass spectrometric characterization of a high-field asymmetric waveform ion mobility spectrometer

    NASA Astrophysics Data System (ADS)

    Purves, Randy W.; Guevremont, Roger; Day, Stephen; Pipich, Charles W.; Matyjaszczyk, Matthew S.

    1998-12-01

    Ion mobility spectrometry (IMS) has become an important method for the detection of many compounds because of its high sensitivity and amenability to miniaturization for field-portable monitoring; applications include detection of narcotics, explosives, and chemical warfare agents. High-field asymmetric waveform ion mobility spectrometry (FAIMS) differs from IMS in that the electric fields are applied using a high-frequency periodic asymmetric waveform, rather than a dc voltage. Furthermore, in FAIMS the compounds are separated by the difference in the mobility of ions at high electric field relative to low field, rather than by compound to compound differences in mobility at low electric field (IMS). We report here the first cylindrical-geometry-FAIMS interface with mass spectrometry (FAIMS-MS) and the MS identification of the peaks observed in a FAIMS compensation voltage (CV) spectrum. Using both an electrometer-based-FAIMS (FAIMS-E) and FAIMS-MS, several variables that affect the sensitivity of ion detection were examined for two (polarity reversed) asymmetric waveforms (modes 1 and 2) each of which yields a unique spectrum. An increase in the dispersion voltage (DV) was found to improve the sensitivity and separation observed in the FAIMS CV spectrum. This increase in sensitivity and the unexpected dissimilarity in modes 1 and 2 suggest that atmospheric pressure ion focusing is occurring in the FAIMS analyzer. The sensitivity and peak locations in the CV spectra were affected by temperature, gas flow rates, operating pressure, and analyte concentration.

  17. Modified gas chromatographic/mass spectrometric method for determination of daminozide in high protein food products.

    PubMed

    Faughnan, K T; Woodruff, M A

    1991-01-01

    A modified version of the Conditt and Baumgardner gas chromatographic/mass spectroscopic (GC/MS) method for determination of daminozide in peanut butter and raw peanuts is described. Daminozide in the food product is hydrolyzed to unsymmetrical dimethylhydrazine (UDMH) by sodium hydroxide digestion. The generated UDMH is distilled from the food matrix and captured by reaction with salicylaldehyde in a condensation trap. Resulting high pH distillates generated by peanuts and peanut products are adjusted back to a pH of 5-6 through addition of glacial acetic acid. After thermal incubation and extraction into methylene chloride, salicylaldehyde dimethylhydrazone is separated from interferences by capillary GC and quantitated by MS using the selective ion monitoring (SIM) mode. Quantitation of daminozide is based on the ratio of the salicylaldehyde dimethylhydrazone molecular ion (m/z 164) to the molecular ion (m/z 153) of the internal standard, 4-nitroanisole. Confirmation of daminozide identity is determined by relative intensity of the m/z 164 ion to the m/z 120 (C7H4ON) ion. Improved m/z 164 ion intensity and reduction of neighboring interferences due to acetic acid treatment permitted a daminozide detection limit of 0.005 ppm in a 50 g sample and an associated 0.02 ppm limit of quantitation. This modification is specific for high protein samples that generate high pH distillates such as peanuts and peanut products and is not specifically intended for analysis of low protein samples.

  18. Laser ionization mass-spectrometric element analysis of soils, drinking, underground and industrial waters

    NASA Astrophysics Data System (ADS)

    Khodyreva, E.; Khodyrev, Y.

    2003-04-01

    For detection of heavy metal salts and determination of their concentrations the laser ionization mass-spectrometry was used as the most sensitive and informative analytical method, which allows to carry out the simultaneously analysis of all elements of the periodical system with limit sensitivity 10-7g/l. The samples of soils, drinking water of the Kreschensky springs, underground and industrial waters from the wells of oil field Romashkin (Tatarstan) were chosen as the object of the research. The method LIMS was tested in experimental area of ?Tatneft¦, where elements Br, Ge, Ga, Zn, Cu, Ni, Co, Fe, Mn, Cr, V, Ti, Sc, K, Ca, Cl, S, P, Si, Al, Mg, Na, Be, B, Li were detected. In respect to possible metal extraction, scandium is of most interest in inspected area because its very high cost and availability of water-soluble pattern (most probable, chloride). Its concentration in one of wells was 1 mg/l in water and 0,01 mg/l in oil. On the basis of the experimental data the schemes of the concentration distribution of heavy metal salt were drawn for the region under investigation and possible ways of their migration were shown.

  19. Targeted and untargeted mass spectrometric approaches in discrimination between Myrtus communis cultivars from Sardinia region.

    PubMed

    Sarais, G; D'Urso, G; Lai, C; Pirisi, F M; Pizza, C; Montoro, P

    2016-09-01

    In the present study, the discrimination of phytochemical content of Myrtus communis berries from different geographical origin and cultivars was explored by Liquid Chromatography-Electrospray Ionization-Fourier Transform-Mass Spectrometry (LC-ESI-FT-MS) metabolic profiling and quantitative analysis. Experiments were carried on myrtle plants grown in an experimental area of Sardinia region, obtained by the germination of seeds taken from berries collected in each part of the region. A preliminary untargeted approach on fruit's extracts was realized by collecting LC-ESI-FT-(Orbitrap)-MS data obtained by operating in negative ion mode and performing principal component analysis with the result of differentiation of samples. In a second step, targeted analysis with a reduced number of variables was realized. A data matrix was obtained by the data fusion of positive and negative ionization LC-ESI-MS results, by using as variables the peak areas of each known compounds. By the observation of principal component analysis, results found that anthocyanins, and mainly derivatives of cyanidin, are the principal marker compounds responsive for the discrimination of samples based on the geographical origin of the seeds. Based on this finding, finally, an LC-diode array detector method was developed, validated and applied for the quantitative analysis of berries' extracts based on 11 commercial standard compounds corresponding to the identified markers. Copyright © 2016 John Wiley & Sons, Ltd.

  20. An integrated mass spectrometric and computational framework for the analysis of protein interaction networks.

    PubMed

    Rinner, Oliver; Mueller, Lukas N; Hubálek, Martin; Müller, Markus; Gstaiger, Matthias; Aebersold, Ruedi

    2007-03-01

    Biological systems are controlled by protein complexes that associate into dynamic protein interaction networks. We describe a strategy that analyzes protein complexes through the integration of label-free, quantitative mass spectrometry and computational analysis. By evaluating peptide intensity profiles throughout the sequential dilution of samples, the MasterMap system identifies specific interaction partners, detects changes in the composition of protein complexes and reveals variations in the phosphorylation states of components of protein complexes. We use the complexes containing the human forkhead transcription factor FoxO3A to demonstrate the validity and performance of this technology. Our analysis identifies previously known and unknown interactions of FoxO3A with 14-3-3 proteins, in addition to identifying FoxO3A phosphorylation sites and detecting reduced 14-3-3 binding following inhibition of phosphoinositide-3 kinase. By improving specificity and sensitivity of interaction networks, assessing post-translational modifications and providing dynamic interaction profiles, the MasterMap system addresses several limitations of current approaches for protein complexes.

  1. Mass spectrometric detection of trace anions: The evolution of paired-ion electrospray ionization (PIESI).

    PubMed

    Breitbach, Zachary S; Berthod, Alain; Huang, Ke; Armstrong, Daniel W

    2016-01-01

    The negative-ion mode of electrospray ionization mass spectrometry (ESI-MS) is intrinsically less sensitive than the positive-ion mode. The detection and quantitation of anions can be performed in positive-ion mode by forming specific ion-pairs during the electrospray process. The paired-ion electrospray ionization (PIESI) method uses specially synthesized multifunctional cations to form positively charged adducts with the anions to be analyzed. The adducts are detected in the positive-ion mode and at higher m/z ratios to produce excellent signal-to-noise ratios and limits of detection that often are orders of magnitude better than those obtained with native anions in the negative-ion mode. This review briefly summarizes the different analytical approaches to detect and separate anions. It focuses on the recently introduced PIESI method to present the most effective dicationic, tricationic, and tetracationic reagents for the detection of singly and multiply charged anions and some zwitterions. The mechanism by which specific structural molecular architectures can have profound effects on signal intensities is also addressed.

  2. Analytical Methodologies for Semiconductor Process Characterization—Novel Mass Spectrometric Methods

    NASA Astrophysics Data System (ADS)

    Vartanian, Victor H.; Goolsby, Brian

    2003-09-01

    New analytical techniques and applications are needed to address the challenges facing the semiconductor industry as transistor feature sizes continue to decrease beyond the 100 nm technology node. Several new applications of quadrupole ion trap (QIT) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry are presented, specifically applied to process tool effluent characterization. A QIT with atmospheric pressure transfer line and pneumatically driven valves is used to characterize a dielectric etch process, with response times comparable to extractive Fourier transform infrared (FTIR) spectroscopy. The QIT allows application of collision-induced dissociation (CID) for structure elucidation, and is useful when high-molecular weight metal organic precursors are used in processes that evolve byproducts that are ambiguous by gas-phase infrared analysis. Similarly, a transportable FTICR with a fixed magnet and pulsed-valve sample introduction allows matrix ion ejection to improve the sensitivity to analyte ions. The FTICR has also been evaluated for a low-pressure chemical vapor deposition (LPCVD) process using a high-molecular weight precursor. Byproducts are ambiguous in FTIR spectra, but the FTICR provided structural confirmation of the effluent species, and is a useful complement to FTIR. The FTICR was also used with FTIR to characterize process tool effluent emissions in a study using SF6 and Ar to plasma etch a candidate metal oxide gate electrode material, RuO2. The results confirmed that no significant amount of RuO4, a toxic byproduct, were produced in this process.

  3. Mass spectrometric approach for identifying putative plasma membrane proteins of Arabidopsis leaves associated with cold acclimation.

    PubMed

    Kawamura, Yukio; Uemura, Matsuo

    2003-10-01

    Although enhancement of freezing tolerance in plants during cold acclimation is closely associated with an increase in the cryostability of plasma membrane, the molecular mechanism for the increased cryostability of plasma membrane is still to be elucidated. In Arabidopsis, enhanced freezing tolerance was detectable after cold acclimation at 2 degrees C for as short as 1 day, and maximum freezing tolerance was attained after 1 week. To identify the plasma membrane proteins that change in quantity in response to cold acclimation, a highly purified plasma membrane fraction was isolated from leaves before and during cold acclimation, and the proteins in the fraction were separated with gel electrophoresis. We found that there were substantial changes in the protein profiles after as short as 1 day of cold acclimation. Subsequently, using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS), we identified 38 proteins that changed in quantity during cold acclimation. The proteins that changed in quantity during the first day of cold acclimation include those that are associated with membrane repair by membrane fusion, protection of the membrane against osmotic stress, enhancement of CO2 fixation, and proteolysis.

  4. On-chip electro membrane extraction with online ultraviolet and mass spectrometric detection.

    PubMed

    Petersen, Nickolaj Jacob; Foss, Sunniva Taule; Jensen, Henrik; Hansen, Steen Honoré; Skonberg, Christian; Snakenborg, Detlef; Kutter, Jörg P; Pedersen-Bjergaard, Stig

    2011-01-01

    Electro membrane extraction was demonstrated in a microfluidic device. The device was composed of a 25 μm thick porous polypropylene membrane bonded between two poly(methyl methacrylate) (PMMA) substrates, each having 50 μm deep channel structures facing the membrane. The supported liquid membrane (SLM) consisted of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of the membrane. The driving force for the extraction was a 15 V direct current (DC) electrical potential applied across the SLM. Samples containing the basic drugs pethidine, nortriptyline, methadone, haloperidol, loperamide, and amitriptyline were used to characterize the system. Extraction recoveries were typically in the range of 65-86% for the different analytes when the device was operated with a sample flow of 2.0 μL/min and an acceptor flow of 1.0 μL/min. With the sample flow at 9.0 μL/min and the acceptor flow at 0.0 μL/min, enrichment factors exceeding 75 were obtained during 12 min of operation from a total sample volume of only 108 μL. The on-chip electro membrane system was coupled online to electrospray ionization mass spectrometry and used to monitor online and real-time metabolism of amitriptyline by rat liver microsomes.

  5. Calibration of Dissolved Noble Gas Mass Spectrometric Measurements by an Air-Water Equilibration System

    NASA Astrophysics Data System (ADS)

    Hillegonds, Darren; Matsumoto, Takuya; Jaklitsch, Manfred; Han, Liang-Feng; Klaus, Philipp; Wassenaar, Leonard; Aggarwal, Pradeep

    2013-04-01

    Precise measurements by mass spectrometry of dissolved noble gases (He, Ar, Ne, Kr, Xe) in water samples require careful calibration against laboratory standards with known concentrations. Currently, air pipettes are used for day-to-day calibrations, making estimation of overall analytical uncertainties for dissolved noble gas measurements in water difficult. Air equilibrated water (AEW) is often used as a matrix-equivalent laboratory standard for dissolved gases in groundwater, because of the well-known and constant fractions of noble gases in the atmosphere. AEW standards, however, are only useful if the temperature and pressure of the gas-water equilibrium can be controlled and measured precisely (i.e., to better than 0.5%); contamination and partial sample degassing must also be prevented during sampling. Here we present the details of a new custom air-water equilibration system which consists of an insulated 600 liter tank filled with deionized water, held isothermally at a precise target temperature (<0.05 °C) through the use of a heat exchanger. The temperature and total dissolved gas of the water in the tank are monitored continually, as are atmospheric pressure and air temperature in the laboratory. Different noble gas concentration standards can be reliably produced by accurately controlling the water temperature of the equilibration system. Equilibration characteristics and reproducibility of this system for production of copper tubes containing known amounts of noble gases will be presented.

  6. LC-high-resolution multiple stage spectrometric analysis of diuretic compounds Unusual mass fragmentation pathways.

    PubMed

    Giancotti, Valeria; Medana, Claudio; Aigotti, Riccardo; Pazzi, Marco; Baiocchi, Claudio

    2008-09-29

    The analysis of diuretic compounds has become of great concern because of their extensive use both in therapy and in illicit treatments (such as masking agents in sport doping and drug abuse). The variety of chemical structures of this class of drugs encouraged the development of new methods and techniques of analysis, especially as regards to acidic compounds. LC/MS has so grown to be the reference technique for this kind of analysis in forensic and anti-doping confirmation purposes. Multiple stage MS permits identification of single drugs with high selectivity, but some unexpected pathways could weaken the entire process. In this work we aim to explain some unusual fragmentation steps using high-resolution MSn. For example, in the case of amiloride an intense product ion in MS3 analysis generates an apparent loss of 10Da. Water adduct formation and successive carbon monoxide elimination can explain this uncommon behavior, which was studied using different ion traps. Bendroflumethiazide MSn spectra show instead three successive HF losses, in spite of the presence of a radical site in the parent structure. Homolytic cleavages with radical ion production occur also in the case of protonated positive ion of ethacrynic acid (loss of chlorine radical) showing that such fragmentation behavior is not so rare as generally reported. Different ionization modes were studied and a tentative correlation with acidic-base properties was done. Multiple stage high-resolution mass spectra of positive and negative ions were discussed.

  7. A Mass Spectrometric Analysis Method Based on PPCA and SVM for Early Detection of Ovarian Cancer.

    PubMed

    Wu, Jiang; Ji, Yanju; Zhao, Ling; Ji, Mengying; Ye, Zhuang; Li, Suyi

    2016-01-01

    Background. Surfaced-enhanced laser desorption-ionization-time of flight mass spectrometry (SELDI-TOF-MS) technology plays an important role in the early diagnosis of ovarian cancer. However, the raw MS data is highly dimensional and redundant. Therefore, it is necessary to study rapid and accurate detection methods from the massive MS data. Methods. The clinical data set used in the experiments for early cancer detection consisted of 216 SELDI-TOF-MS samples. An MS analysis method based on probabilistic principal components analysis (PPCA) and support vector machine (SVM) was proposed and applied to the ovarian cancer early classification in the data set. Additionally, by the same data set, we also established a traditional PCA-SVM model. Finally we compared the two models in detection accuracy, specificity, and sensitivity. Results. Using independent training and testing experiments 10 times to evaluate the ovarian cancer detection models, the average prediction accuracy, sensitivity, and specificity of the PCA-SVM model were 83.34%, 82.70%, and 83.88%, respectively. In contrast, those of the PPCA-SVM model were 90.80%, 92.98%, and 88.97%, respectively. Conclusions. The PPCA-SVM model had better detection performance. And the model combined with the SELDI-TOF-MS technology had a prospect in early clinical detection and diagnosis of ovarian cancer.

  8. MALDI Mass Spectrometric Imaging of Lipids in Rat Brain Injury Models

    NASA Astrophysics Data System (ADS)

    Hankin, Joseph A.; Farias, Santiago E.; Barkley, Robert M.; Heidenreich, Kim; Frey, Lauren C.; Hamazaki, Kei; Kim, Hee-Yong; Murphy, Robert C.

    2011-06-01

    Matrix-assisted laser desorption ionization/ionization imaging mass spectrometry (MALDI IMS) with a time-of-flight analyzer was used to characterize the distribution of lipid molecular species in the brain of rats in two injury models. Ischemia/reperfusion injury of the rat brain after bilateral occlusion of the carotid artery altered appearance of the phospholipids present in the hippocampal region, specifically the CA1 region. These brain regions also had a large increase in the ion abundance at m/z 548.5 and collisional activation supported identification of this ion as arising from ceramide (d18:1/18:0), a lipid known to be associated with cellular apoptosis. Traumatic brain injury model in the rat was examined by MALDI IMS and the area of damage also showed an increase in ceramide (d18:1/18:0) and a remarkable loss of signal for the potassium adduct of the most abundant phosphocholine molecular species 16:0/18:1 (PC) with a corresponding increase in the sodium adduct ion. This change in PC alkali attachment ion was suggested to be a result of edema and influx of extracellular fluid likely through a loss of Na/K-ATPase caused by the injury. These studies reveal the value of MALDI IMS to examine tissues for changes in lipid biochemistry and will provide data needed to eventually understand the biochemical mechanisms relevant to tissue injury.

  9. Mass Spectrometric Measurement of Neuropeptide Secretion in the Crab, Cancer borealis, by In Vivo Microdialysis

    PubMed Central

    Liang, Zhidan; Schmerberg, Claire M.; Li, Lingjun

    2015-01-01

    Neuropeptides (NPs), a unique and highly important class of signaling molecules across the animal kingdom, have been extensively characterized in the neuronal tissues of various crustaceans. Because many NPs are released into circulating fluid (hemolymph) and travel to distant sites in order to exhibit physiological effects, it is important to measure the secretion of these NPs from living animals. In this study, we report on extensive characterization of NPs released in the crab Cancer borealis by utilizing in vivo microdialysis to sample NPs from the hemolymph. We determined the necessary duration for collection of microdialysis samples, enabling more comprehensive identification of NP content while maintaining the temporal resolution of sampling. Analysis of in vivo microdialysates using a hybrid quadrupole-Orbitrap™ Q-Exactive mass spectrometer revealed that more than 50 neuropeptides from 9 peptide families—including the allatostatin, RFamide, orcokinin, tachykinin-related peptide and RYamide families–were released into the circulatory system. The presence of these peptides both in neuronal tissues as well as in hemolymph indicates their putative hormonal roles, a finding that merits further investigation. Preliminary quantitative measurement of these identified NPs suggested several potential candidates that may be associated with the circadian rhythm in Cancer borealis. PMID:25537886

  10. Electrospray ionization mass spectrometric observation of ligand exchange of zinc pyrithione with amino acids.

    PubMed

    Moriwaki, Hiroshi; Okabayashi, Masanori; Watanabe, Takehiro; Kawasaki, Hideya; Arakawa, Ryuichi

    2009-07-01

    Zinc pyrithione (ZnPT) is widely used as an antidandruff or antifouling reagent. However, this compound is considered toxic, such as the teratogenic effect, to aquatic lives, and it is important to clarify the mechanism of its toxicity. In this study, the interactions between ZnPT and amino acids were observed using electrospray ionization mass spectrometry (ESI-MS) in order to obtain information on the activity of ZnPT within the living body. The ZnPT complex ([ZnPT-ligand+Amino acid]+), in which the ligand of ZnPT was exchanged by the amino acid, was detected in ZnPT solutions mixed with one of 20 amino acids by ESI-MS. Histidine and cysteine, in particular, showed a high reactivity with ZnPT, while serine and glycine showed a low reactivity. The complexes of ZnPT and a peptide were also observed by the ESI-MS measurement of the solution containing ZnPT with the peptide. These results would be useful to understand the mechanism of ZnPT toxicities to living creatures.

  11. Mass spectrometric methods to analyze the structural organization of macromolecular complexes.

    PubMed

    Rajabi, Khadijeh; Ashcroft, Alison E; Radford, Sheena E

    2015-11-01

    With the development of soft ionization techniques such as electrospray ionization (ESI), mass spectrometry (MS) has found widespread application in structural biology. The ability to transfer large biomolecular complexes intact into the gas-phase, combined with the low sample consumption and high sensitivity of MS, has made ESI-MS a method of choice for the characterization of macromolecules. This paper describes the application of MS to study large non-covalent complexes. We categorize the available techniques in two groups. First, solution-based techniques in which the biomolecules are labeled in solution and subsequently characterized by MS. Three MS-based techniques are discussed, namely hydroxyl radical footprinting, cross-linking and hydrogen/deuterium exchange (HDX) MS. In the second group, MS-based techniques to probe intact biomolecules in the gas-phase, e.g. side-chain microsolvation, HDX and ion mobility spectrometry are discussed. Together, the approaches place MS as a powerful methodology for an ever growing plethora of structural applications.

  12. Mass spectrometric and quantum chemical determination of proton water clustering equilibria

    NASA Astrophysics Data System (ADS)

    Likholyot, Alexander; Lemke, Kono H.; Hovey, Jamey K.; Seward, Terry M.

    2007-05-01

    We report on the thermochemistry of proton hydration by water in the gas phase both experimentally using high-pressure mass spectrometry (HPMS) and theoretically using multilevel G3, G3B3, CBS-Q, CBS-QB3, CBS/QCI-APNO as well as density functional theory (DFT) calculations. Gas phase hydration enthalpies and entropies for protonated water cluster equilibria with up to 7 waters (i.e., n ⩽ 7H 3O +·(H 2O) n) were observed and exhibited non-monotonic behavior for successive hydration steps as well as enthalpy and entropy anomalies at higher cluster rank numbers. In particular, there is a significant jump in the stepwise enthalpies and entropies of cluster formation for n varying from 6 to 8. This behavior can be successfully interpreted using cluster geometries obtained from quantum chemical calculations by considering the number of additional hydrogen bonds formed at each hydration step and simultaneous weakening of ion-solvent interaction with increasing cluster size. The measured total hydration energy for the attachment of the first six water molecules around the hydronium ion was found to account for more than 60% of total bulk hydration free energy.

  13. Ultrafast High-Resolution Mass Spectrometric Finger Pore Imaging in Latent Finger Prints

    PubMed Central

    Elsner, Christian; Abel, Bernd

    2014-01-01

    Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record ‘three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high- spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals. PMID:25366032

  14. Chemical, mass spectrometric, and spectrochemical analysis of, and physical tests on, beryllium oxide powder

    SciTech Connect

    Not Available

    1981-01-01

    Beryllium oxide is used in the fabrication of nuclear components. In order to be suitable for this purpose, the material must meet certain criteria for impurity content and physical properties. The analytical and physical testing procedures in this standard are designed to show whether or not a given material meets accepted specifications. Test methods described in detail are: total carbon by the combustion-thermal conductivity method; iron by colorimetric (orthophenanthroline) method; nitride nitrogen by the micro Kjeldahl method; chloride by nephelometry; lithium by atomic absorption spectrophotometry; sulfur by combustion-iodometric titration method; beryllium oxide in beryllium oxide powders by impurity correction method; trace elements by the complete-burning spectrochemical method; impurity elements by a spark-source mass spectrographic method; density by toluene displacement method; density (pour and tap) by the tap-pak volumetric method; particle size distribution analysis by the coulter counter method; sieve analysis; bulk and real densities, porosity, and pore size-pore volume distribution mercury-penetration porosimetry; surface area by nitrogen absorption method. (JMT)

  15. Mass spectrometric detection of CP4 EPSPS in genetically modified soya and maize.

    PubMed

    Ocaña, Mireia Fernández; Fraser, Paul D; Patel, Raj K P; Halket, John M; Bramley, Peter M

    2007-01-01

    The potential of protein fractionation hyphenated to mass spectrometry (MS) to detect and characterize the transgenic protein present in Roundup Ready soya and maize has been investigated. Genetically modified (GM) soya and maize contain the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from Agrobacterium tumefaciens CP4, which confers resistance to the herbicide glyphosate. The GM soya and maize proteomes were fractionated by gel filtration, anion-exchange chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) prior to MS. This facilitated detection of a tryptic peptide map of CP4 EPSPS by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nanoelectrospray ionization quadrupole time-of-flight (nanoESI-QTOF) MS. Subsequently, sequence information from the CP4 EPSPS tryptic peptides was obtained by nanoESI-QTOF MS/MS. The identification was accomplished in 0.9% GM soya seeds, which is the current EU threshold for food-labeling requirements.

  16. Tandem mass spectrometric analysis of a mixture of isobars using the survival yield technique.

    PubMed

    Memboeuf, Antony; Jullien, Laure; Lartia, Rémy; Brasme, Bernard; Gimbert, Yves

    2011-10-01

    Collision induced dissociation tandem mass spectrometry experiments were performed to unequivocally separate compounds from an isobaric mixture of two products. The Survival Yield curve was obtained and is shown to consist in a linear combination of the curves corresponding to the two components separately. For such a mixture, a plateau appears on the diagram in lieu of the continuous decrease expected allowing for the structural study of the two components separately. The width of the plateau critically relates to the fragmentation parameters of the two molecular ions, which need to be sufficiently different structurally for the plateau to be observed. However, at constant fragmentation parameters, we have observed the width significantly increases at large m/z. This makes the separation more and more efficient as isobars have larger m/z and the technique complementary to those applicable at low m/z only. We have observed that the vertical position of the plateau relates linearly to the relative concentration of the two compounds that may be useful for quantification. Repeatability was estimated at 2% on a quadrupole ion trap. An advantage of using survival yield curves only, is that a priori knowledge of the respective fragmentation patterns of the two isobars becomes unnecessary. Consequently, similar performances are obtained if fragments are isobaric, which is also demonstrated in our study. The critical case of reverse peptides, at low m/z and similar fragmentation parameters, is also presented as a limitation of the method.

  17. A Mass Spectrometric Analysis Method Based on PPCA and SVM for Early Detection of Ovarian Cancer

    PubMed Central

    Wu, Jiang; Ji, Mengying; Ye, Zhuang

    2016-01-01

    Background. Surfaced-enhanced laser desorption-ionization-time of flight mass spectrometry (SELDI-TOF-MS) technology plays an important role in the early diagnosis of ovarian cancer. However, the raw MS data is highly dimensional and redundant. Therefore, it is necessary to study rapid and accurate detection methods from the massive MS data. Methods. The clinical data set used in the experiments for early cancer detection consisted of 216 SELDI-TOF-MS samples. An MS analysis method based on probabilistic principal components analysis (PPCA) and support vector machine (SVM) was proposed and applied to the ovarian cancer early classification in the data set. Additionally, by the same data set, we also established a traditional PCA-SVM model. Finally we compared the two models in detection accuracy, specificity, and sensitivity. Results. Using independent training and testing experiments 10 times to evaluate the ovarian cancer detection models, the average prediction accuracy, sensitivity, and specificity of the PCA-SVM model were 83.34%, 82.70%, and 83.88%, respectively. In contrast, those of the PPCA-SVM model were 90.80%, 92.98%, and 88.97%, respectively. Conclusions. The PPCA-SVM model had better detection performance. And the model combined with the SELDI-TOF-MS technology had a prospect in early clinical detection and diagnosis of ovarian cancer. PMID:27642365

  18. MALDI-TOF mass spectrometric determination of eight benzodiazepines with two of their metabolites in blood.

    PubMed

    Nozawa, Hideki; Minakata, Kayoko; Yamagishi, Itaru; Hasegawa, Koutaro; Wurita, Amin; Gonmori, Kunio; Suzuki, Osamu; Watanabe, Kanako

    2015-05-01

    A rapid and sensitive method was developed for the determination of benzodiazepines and benzodiazepine-like substances (BZDs) by matrix-assisted laser desorption ionization (MALDI)-time-of-flight (TOF)-mass spectrometry (MS). In this method, α-cyano-4-hydroxy cinnamic acid was used as the matrix to assist the ionization of BZDs. Determination of 8 BZDs (with two of their metabolites) belonging to top 12 medical drugs detected in poisonous cases in Japan, was performed using diazepam-d5 as the internal standard. The limit of detection of zolpidem was 0.07ng/ml with its quantification range of 0.2-20ng/ml in blood, in the best case, and the limit of detection of flunitrazepam was 2ng/ml with its quantification range of 6-200ng/ml in blood, in the worst case. The spectra of zopiclone in MALDI-MS and MS/MS were different from those in electrospray ionization MS and MS/MS. Present method provides a simple and high throughput method for the screening of these BZDs using only 20μl of blood. The developed method was successfully used for the determination of BZDs in biological fluids obtained from two victims.

  19. Magnetic solid phase extraction and gas chromatography-mass spectrometrical analysis of sixteen polycyclic aromatic hydrocarbons.

    PubMed

    Cai, Ying; Yan, Zhihong; NguyenVan, Manh; Wang, Lijia; Cai, Qingyun

    2015-08-07

    Fluorenyl functionalized superparamagnetic core/shell magnetic nanoparticles (MNPs, Fe3O4@SiO2@Flu) were prepared and characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The MNPs having an average diameter of 200nm were then used as solid-phase extraction sorbent for the determination of 16 priority pollutants polycyclic aromatic hydrocarbons (PAHs) in water samples designated by United States Environmental Protection Agency (U.S. EPA). The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time were optimized. Analyses were performed on gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) mode. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels. Limit of detection ranging from 0.5 to 4.0ng/L were obtained. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 13.1%. Finally, the proposed method was successfully applied for the determination of PAHs in water samples with the recoveries in the range of 96.0-106.7%.

  20. The importance of mass spectrometric dereplication in fungal secondary metabolite analysis

    PubMed Central

    Nielsen, Kristian F.; Larsen, Thomas O.

    2015-01-01

    Having entered the Genomic Era, it is now evident that the biosynthetic potential of filamentous fungi is much larger than was thought even a decade ago. Fungi harbor many cryptic gene clusters encoding for the biosynthesis of polyketides, non-ribosomal peptides, and terpenoids – which can all undergo extensive modifications by tailoring enzymes – thus potentially providing a large array of products from a single pathway. Elucidating the full chemical profile of a fungal species is a challenging exercise, even with elemental composition provided by high-resolution mass spectrometry (HRMS) used in combination with chemical databases (e.g., AntiBase) to dereplicate known compounds. This has led to a continuous effort to improve chromatographic separation in conjunction with improvement in HRMS detection. Major improvements have also occurred with 2D chromatography, ion-mobility, MS/MS and MS3, stable isotope labeling feeding experiments, classic UV/Vis, and especially automated data-mining and metabolomics software approaches as the sheer amount of data generated is now the major challenge. This review will focus on the development and implementation of dereplication strategies and will highlight the importance of each stage of the process from sample preparation to chromatographic separation and finally toward both manual and more targeted methods for automated dereplication of fungal natural products using state-of-the art MS instrumentation. PMID:25741325

  1. Mass spectrometric analysis of the glycosphingolipid-enriched microdomains of rat natural killer cells.

    PubMed

    Man, Petr; Novák, Petr; Cebecauer, Marek; Horváth, Ondrej; Fiserová, Anna; Havlícek, Vladimír; Bezouska, Karel

    2005-01-01

    Glycosphingolipid-enriched microdomains (GEM) are membrane entities that concentrate glycosylphosphatiolylinositol(GPI)-anchored, acylated and membrane proteins important for immune receptor signaling. Using rat leukemic cell line RNK-16 we have initiated proteomic studies of microdomains in natural killer (NK) cells. Isolated plasma membranes were treated with Brij 58, or Nonidet-P40, or sodium carbonate. Extracts were separated by sucrose density gradient centrifugation into very light membrane, medium light membrane and heavy fractions, and a complete protein profile was analyzed by tandem mass spectrometry. Up to 250 proteins were unambiguously identified in each analyzed fraction. The first study of the proteome of NK cell GEM revealed several new aspects including identification of molecules not expected to be expressed in rat NK cells (e.g., NAP-22) or associated with GEM (e.g., NKR-P1, CD45, CD2). Moreover, it provided clear data consolidating controversial views concerning the occurrence of major histcompatibility complex glycoproteins and RT6.1/CD73/CD38 complex in NK cells. Our results also identified a large number of receptors as candidates for future functional studies.

  2. Mass spectrometry investigation of Titan aerosols analogs formed with traces of aromatic compounds

    NASA Astrophysics Data System (ADS)

    Gautier, Thomas; Trainer, Melissa; Sebree, Joshua; Li, Xiang; Pinnick, Veronica; Getty, Stephanie; Brinckerhoff, Will

    2016-06-01

    The detection of benzene at ppm levels in Titan's atmosphere [1] by Cassini's Ion and Neutral Mass Spectrometer (INMS) supports the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titan's aerosols formation. In laboratory studies it has been shown that these aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation [2] and be used to dope the production of aerosol analogs [3]. In this work we investigate the effect on the aerosol composition and growth pattern of the chemical nature of the aromatic reactant used to produce aerosol. Analysis are performed using Laser Desorption-Time of Flight mass spectrometry (LD-TOF) and Fourier Transform Infrared Spectroscopy (FTIR) Infrared analysis of our samples shows that inclusion of aromatic compounds as trace precursors allows to better fit laboratory data to Titan aerosol spectra observed by Cassini [3,4]. The improvement is especially visible on the far infrared (˜200 cm-1) bands observed by CIRS [5]. LDMS results show that the aerosol growth patterns depend both on the number of rings and on the nitrogen content of the trace precursor used. We also perform MS/MS analysis on some prominent peaks of aerosol mass spectra. This MS/MS approach allows us to identify some of the key compounds in the aerosol growth processes.

  3. Capture, enrichment, and mass spectrometric detection of low-molecular-weight biomarkers with nanoporous silicon microparticles.

    PubMed

    Tan, Jie; Zhao, Wei-Jie; Yu, Jie-Kai; Ma, Sai; Sailor, Michael J; Wu, Jian-Min

    2012-11-01

    Mining the disease information contained in the low-molecular-weight range of a proteomic profile is becoming of increasing interest in cancer research. This work evaluates the ability of nanoporous silicon microparticles (NPSMPs) to capture, enrich, protect, and detect low-molecular-weight peptides (LMWPs) sieved from a pool of highly abundant plasma proteins. The average pore size and porosity of NPSMPs are controlled by the electrochemical preparation conditions, and the critical parameters for admission or exclusion of protein with a definite molecular weight are determined by reflectometric-interference Fourier transform spectroscopy (RIFTS). Sodium dodecyl sulfate polyacrylamide-gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) analysis of the proteins captured by the NPSMPs show that the chemical nature of the NPSMPs surface and the solution pH also play vital roles in determining the affinity of NPSMPs for target analytes. It is found that carboxyl-terminated porous microparticles with a porosity of 26% (pore diameter around 9.0 nm) specifically fractionate, enrich and protect LMWPs sieved from either simulated samples or human serum samples. Moreover, NPSMPs containing captured peptides can be directly spotted onto a MALDI plate. When placed in a conventional MALDI matrix, laser irradiation of the particles results in the release of the target peptides confined in the nanopores, which are then ionized and detected in the MALDI experiment. As a proof-of-principle test case, mass spectra of NPSMPs prepared using serum from colorectal cancer patients and from control patients can be clearly distinguished by statistical analysis. The work demonstrates the utility of the method for discovery of biomarkers in the untapped LMWP fraction of human serum, which can be of significant value in the early diagnosis and management of diseases.

  4. Selective Chemoprecipitation to Enrich Nitropeptides from Complex Proteomes for Mass Spectrometric Analysis

    PubMed Central

    Prokai, Laszlo; Guo, Jia; Prokai-Tatrai, Katalin

    2015-01-01

    Posttranslational protein nitration has attracted interest due to its involvement in cellular signaling, effects on protein function, and as a potential biomarker of nitroxidative stress. We describe a procedure for enriching nitropeptides for mass spectrometry-based proteomics that is a simple and reliable alternative to immunoaffinity-based methods. The starting material for this procedure is a proteolytic digest. The peptides are reacted with formaldehyde and sodium cyanoborohydride to dimethylate all the N-terminal and side-chain amino groups. Sodium dithionite is added subsequently to reduce the nitro groups to amines; in theory, the only amino groups present will have originally been nitro groups. The peptide sample is then applied to a solid-phase active ester reagent, and those peptides with amino groups will be selectively and covalently captured. Release of the peptides on hydrolysis with trifluoroacetic acid results in peptides that have a 4-formyl-benzamido group where the nitro group used to be. In qualitative setups, the procedure can be used to identify proteins modified by reactive nitrogen species and to determine the specific sites of their nitration. Quantitative measurements can be performed by stable-isotope labeling of the peptides in the reductive dimethylation step. Preparation of the solid-phase active ester reagent takes about 1 day. Enrichment of nitropeptides requires about 2 days, and sample preparations need 1 to 30 h varying based on experimental design. LC–MS/MS assays take from 4 h to several days and data processing can be done 1 to 7 days. PMID:24651500

  5. Constraining geochemistry and biological primary productivity in hydrothermal systems via in situ mass spectrometric geochemical mapping

    NASA Astrophysics Data System (ADS)

    Vidoudez, Charles; Marcon, Yann; Bach, Wolfgang; Lebris, Nadine; Dubilier, Nicole; Girguis, Peter

    2014-05-01

    Hydrothermal vent ecosystems are biological hot spots, supported by chemoautotrophic primary productivity and achieving densities comparable to rainforests. Nevertheless, our understanding of the geochemical factors that govern the distribution of animals and microbes within vents is limited. It is well known that vent endemic organisms are found in specific vent "microenvironments", and that these microenvironments are distributed -coarsely speaking- in predictable patterns within a vent field. However, the relative differences in activity among these faunal patches, and their role in influencing geochemical flux remains largely unknown due to historical limitations in our ability to sample and quantify geochemical constituents with fine spatial resolution. In particular, the distribution of biologically important volatiles around vent fields is poorly constrained, as is the degree to which their distribution influences the destiny and distribution of organisms. To characterize the relationship between the distribution of volatiles, chemosynthetic microbes, and chemosynthetic symbioses, we generated detailed geo-referenced maps of methane, hydrogen sulfide, carbon dioxide and oxygen (four of the key volatiles that are both vent- and seawater derived) using an in situ mass spectrometer (ISMS). We characterized these concentrations in over 130 spots across three vent sites associated with the mid-Atlantic ridge in the Menez Gwen vent field. We quantified gases in sites ranging from hot fluids to mussel beds, and found notable relationships between the distribution and consumption of hydrogen sulfide and methane and the animal and microbial communities. Finally, we also developed a metabolic energy "map", which enables us to constrain both the potential energy that is available to these communities as well as the extent to which it is being used, and places constraints on the extent of primary production that can be supported by the realized use of these volatiles.

  6. Photochemical vapor generation of lead for inductively coupled plasma mass spectrometric detection

    NASA Astrophysics Data System (ADS)

    Duan, Hualing; Zhang, Ningning; Gong, Zhenbin; Li, Weifeng; Hang, Wei

    2016-06-01

    Photochemical vapor generation (PCVG) of lead was successfully achieved with a simplified and convenient system, in which only low molecular weight organic acid and a high-efficiency photochemical reactor were needed. The reactor was used to generate lead volatile species when a solution of lead containing a small amount of low molecular weight organic acid was pumped through. Several factors, including the concentration of acetic acid, the concentration of hydrochloride acid, and the irradiation time of UV light were optimized. Under the optimal conditions, including the addition of 0.90% (v/v) acetic acid and 0.03% (v/v) hydrochloride acid, and irradiation time of 28 s, intense and repeatable signal of lead volatile species was successfully obtained and identified with inductively coupled plasma mass spectrometry (ICPMS). In addition, the effects from inorganic anions and transition metal ions, including Cl-, NO3-, SO42 -, Cu2 +, Fe3 +, Co2 + and Ni2 +, were investigated, which suggests that their suppression to the PCVG of lead was in the order of Cl- < SO42 - < NO3- for anions and Ni2 +, Co2 + < Fe3 + < Cu2 + for transition metal ions. Under optimized conditions, relative standard derivation (RSD) of 4.4% was achieved from replicate measurements (n = 5) of a standard solution of 0.1 μg L- 1 lead. And, the limit of quantitation (LOQ, 10σ) of 0.012 μg L- 1 lead was obtained using this method and the method blank could be easily controlled down to 0.023 μg L- 1. To validate applicability of this method, it was also employed for the determination of lead in tap water, rain water and lake water.

  7. Thermal desorption mass spectrometric and x-ray photoelectron studies of etched surfaces of polytetrafluoroethylene

    NASA Astrophysics Data System (ADS)

    Rye, R. R.; Kelber, J. A.

    1987-12-01

    The etching of polytetrafluoroethylene (PTFE) with Na solutions is known to lead to a loss of F, a loss which is correlated with enhanced adhesion. Subsequent heating partially restores surface F with a concurrent loss of adhesion strength. We have combined X-ray photoelectron spectroscopy (XPS) and gas phase mass spectroscopy for in situ measurements of the processes that occur as the fluorocarbon is heated. An array of volatile products, which vary with the specific treatment, desorb from etched PTFE. Among these are: N 2 and low molecular weight fluorocarbons, the amounts of which monotonically decrease with increasing exposure to the etching solution (and probably result from the bulk); species such as CO and CO 2, which in part result from surface impurities; and water and acetone which result from the rinse steps following the etching process. XPS measurements show that etching produces a major loss of surface F and a gain of surface O. The latter probably results from the subsequent rinse steps. Heating produces a substantial recovery in surface F with only a small decrease in the surface O, and the gain in surface F is shown to occur at a higher temperature than the desorption of any species from the surface. Thus, desorption of products from the surface is decoupled, in terms of both the distribution of products and their relative temperatures, from the surface changes as monitored by XPS. This decoupling suggests that the increase in surface F results from diffusion of low molecular weight fluorocarbons from the bulk or a transition region, or from a rearrangement of the sponge-like surface region produced in the etching process.

  8. Mass Spectrometric Characterization of Protein Structure Details Refines the Proteome Signature for Invasive Ductal Breast Carcinoma

    NASA Astrophysics Data System (ADS)

    Röwer, Claudia; Koy, Cornelia; Hecker, Michael; Reimer, Toralf; Gerber, Bernd; Thiesen, Hans-Jürgen; Glocker, Michael O.

    2011-03-01

    Early diagnosis as well as individualized therapies are necessary to reduce the mortality of breast cancer, and personalized patient care strategies rely on novel prognostic or predictive factors. In this study, with six breast cancer patients, 2D gel analysis was applied for studying protein expression differences in order to distinguish invasive ductal breast carcinoma, the most frequent breast tumor subtype, from control samples. In total, 1203 protein spots were assembled in a 2D reference gel. Differentially abundant spots were subjected to peptide mass fingerprinting for protein identification. Twenty proteins with their corresponding 38 differentially expressed 2D gel spots were contained in our previously reported proteome signature, suggesting that distinct protein forms were contributing. In-depth MS/MS measurements enabled analyses of protein structure details of selected proteins. In protein spots that significantly contributed to our signature, we found that glyceraldehyde-3-phosphate dehydrogenase was N-terminally truncated, pyruvate kinase M2 and nucleoside diphosphate kinase A but not other isoforms of these proteins were of importance, and nucleophosmin phosphorylation at serine residues 106 and 125 were clearly identified. Principle component analysis and hierarchical clustering with normalized quantitative data from the 38 spots resulted in accurate separation of tumor from control samples. Thus, separation of tissue samples as in our initial proteome signature could be confirmed even with a different proteome analysis platform. In addition, detailed protein structure investigations enabled refining our proteome signature for invasive ductal breast carcinoma, opening the way to structure-/function studies with respect to disease processes and/or therapeutic intervention.

  9. Determination of sirolimus in rabbit arteries using liquid chromatography separation and tandem mass spectrometric detection.

    PubMed

    Zhang, Jun; Rodila, Ramona; Watson, Pamela; Ji, Qin; El-Shourbagy, Tawakol A

    2007-10-01

    Sirolimus, an effective immunosuppressive agent, is used for drug eluting stents. During stent development, an analytical method for the determination of sirolimus in tissue needs to be established. Normally, tissue samples are homogenized and then analyzed against the calibration standards prepared in a tissue homogenate. This approach provides insufficient control of the homogenization process. In this paper, tissue quality control samples were introduced for the optimization of the homogenization process during method development, but also allowance for the performance evaluation of the entire analytical process. In addition, a new approach using rabbit blood as a homogenization medium was developed to stabilize sirolimus in rabbit tissue homogenates. Calibration standards and quality controls were prepared by spiking different sirolimus working solutions into rabbit blood. Homogenization quality control samples were prepared by injecting other sirolimus working solutions into empty test tubes and pre-cut arteries within pre-defined masses. A high-throughput homogenization procedure was optimized based on the specific chemical properties of sirolimus. The linear dynamic range was between 49.9 pg/mL and 31.9 ng/mL to accommodate the expected artery homogenate concentrations. Additionally, quality controls in rabbit blood were also used in the extraction to support the calibration standards. The accuracy and precision of the quality controls in rabbit blood reflect the extraction performance and the accuracy and precision of the homogenization tissue quality controls reflect the overall performance of the method. The mean bias was between -4.5 and 0.2% for all levels of quality controls in the blood and between 4.8 and 14.9% for all levels of the homogenization tissue quality controls. The CVs of all concentration levels were < or =5.3% for the quality controls in blood and < or =9.2% for the homogenization tissue quality controls. The method was successfully

  10. Spatial perspectives in the redox code-Mass spectrometric proteomics studies of moonlighting proteins.

    PubMed

    Pinto, Gabriella; Radulovic, Marko; Godovac-Zimmermann, Jasminka

    2016-05-17

    trafficking of proteins offered by MS-based proteomics has a unique, crucial role to play in deciphering the complex adaptive systems that underlie cellular function. © 2016 Wiley Periodicals, Inc. Mass Spec Rev.

  11. Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Al-Cu-Sn alloy

    NASA Astrophysics Data System (ADS)

    Bencze, L.; Milacic, R.; Jacimovic, R.; Zigon, D.; Mátyás, L.; Popovic, A.

    2010-01-01

    The vaporisation of a liquid Al-Cu-Sn system has been investigated at 1273-1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich-Kister-Muggianu (RKM) sub-regular solution model. Thirty-one different compositions (41 samples) have been examined at eight fixed copper mole fractions, XCu = 0.10, 0.20, 0.30, 0.333, 0.40, 0.50, 0.60 and 0.70. The ternary L-parameters, the thermodynamic activities and the thermodynamic functions of mixing have been evaluated using standard KEMS procedures. In addition, the same quantities were obtained from the measured ion intensity ratios of Al+ to Cu+, Al+ to Sn+ and Cu+ to Sn+ using a mathematical regression technique. The intermediate data obtained directly are the RKM ternary L-parameters that are, as a function of temperature, as follows:L(0)=(14270+/-1270)+(100.1+/-7.6)T-(11.77+/-0.93)T[thin space]ln(T);L(1)=(145600+/-9780)+(101.6+/-58.7)T-(15.56+/-7.14)T[thin space]ln(T);L(2)=(76730+/-1240)+(79.2+/-7.4)T-(15.69+/-0.91)T[thin space]ln(T). From the obtained ternary L-parameters the integral molar excess Gibbs energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies can be also determined. In addition, for comparison, for some compositions, the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs-Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained from the RKM model.

  12. Characterization of Peptide Polymer Interactions in Poly(alkylcyanoacrylate) Nanoparticles: A Mass Spectrometric Approach.

    PubMed

    Kafka, Alexandra P; Kleffmann, Torsten; Rades, Thomas; McDowell, Arlene

    2010-07-01

    Drug/polymer interactions occur during in situ polymerization of poly(alkylcyanoacrylate) (PACA) formulations. We have used MALDI ionization coupled tandem time-of-flight (TOF) mass spectrometry as an accurate method to characterize covalent peptide/polymer interactions of PACA nanoparticles with the bioactives D-Lys6-GnRH, insulin, [Asn1-Val5]-angiotensin II, and fragments of insulin-like growth factor 1 (IGF-1 (1-3)) and human adrenocorticotropic hormone (h-ACTH, (18-39)) at the molecular level. Covalent interactions of peptide with alkylcyanoacrylate were identified for D-Lys6-GnRH, [Asn1-Val5]-angiotensin II and IGF-1 (1-3). D-Lys6-GnRH and [Asn1-Val5]-angiotensin II were modified at their histidine side chain within the peptide, whilst IGF-1 (1-3) was modified at the C-terminal glutamic acid residue. The more complex protein insulin was not modified despite the presence of 2 histidine residues. This might be explained by the engagement of histidine residues in the folding and sterical arrangement of insulin under polymerization conditions. As expected, h-ACTH (18-39) that does not contain histidine residues did not interfere in the polymerization process. Lowering the pH did not prevent the covalent association of PACA with D-Lys6-GnRH or IGF-1 (1-3). Conclusively, protein and peptide bioactives are potentially reactive towards alkylcyanoacrylate monomers via various mechanisms with limited interference of pH. Histidines and C-terminal glutamic acid residues have been identified as potential sites of interaction. The likelihood of their engagement in the polymerization process (initiators), however, seems dependent on their sterical availability. The reactivity of nucleophilic functional groups should always be considered and bioactives examined for their potential to covalently interfere with alkylcyanoacrylate monomers, especially when designing PACA delivery systems for protein and peptide biopharmaceuticals.

  13. Characterization of Peptide Polymer Interactions in Poly(alkylcyanoacrylate) Nanoparticles: A Mass Spectrometric Approach.

    PubMed

    Kafka, Alexandra P; Kleffmann, Torsten; Rades, Thomas; McDowell, Arlene

    2010-02-17

    Drug/polymer interactions occur during in situ polymerization of poly(alkylcyanoacrylate) (PACA) formulations. We have used MALDI ionization coupled tandem time-of-flight (TOF) mass spectrometry as an accurate method to characterize covalent peptide/polymer interactions of PACA nanoparticles with the bioactives D-Lys6-GnRH, insulin, [Asn1-Val5]-angiotensin II, and fragments of insulin-like growth factor 1 (IGF-1 (1-3)) and human adrenocorticotropic hormone (h-ACTH, (18-39)) at the molecular level. Covalent interactions of peptide with alkylcyanoacrylate were identified for D-Lys6-GnRH, [Asn1-Val5]-angiotensin II and IGF-1 (1-3). D-Lys6-GnRH and [Asn1-Val5]-angiotensin II were modified at their histidine side chain within the peptide, whilst IGF-1 (1-3) was modified at the C-terminal glutamic acid residue. The more complex protein insulin was not modified despite the presence of 2 histidine residues. This might be explained by the engagement of histidine residues in the folding and sterical arrangement of insulin under polymerization conditions. As expected, h-ACTH (18-39) that does not contain histidine residues did not interfere in the polymerisation process. Lowering the pH did not prevent the covalent association of PACA with D-Lys6-GnRH or IGF-1 (1-3). Conclusively, protein and peptide bioactives are potentially reactive towards alkylcyanoacrylate monomers via various mechanisms with limited interference of pH. Histidines and C-terminal glutamic acid residues have been identified as potential sites of interaction. The likelihood of their engagement in the polymerisation process (initiators), however, seems dependant on their sterical availability. The reactivity of nucleophilic functional groups should always be considered and bioactives examined for their potential to covalently interfere with alkylcyanoacrylate monomers, especially when designing PACA delivery systems for protein and peptide biopharmaceuticals.

  14. Clustering and diagnostic modelling of slimming aids based on chromatographic and mass spectrometric fingerprints.

    PubMed

    Custers, D; Van Hoeck, E; Courselle, P; Apers, S; Deconinck, E

    2017-02-01

    Herbal medicines and food supplements intended as slimming aids are increasingly gaining popularity worldwide, especially for treating obesity. In this study, an ultra-performance liquid chromatography coupled to photodiode array detection (UPLC-PDA) and an ultra-performance liquid chromatography mass spectrometry (UPLC-MS) method were developed to analyze 92 slimming aids (confiscated by customs), aimed at acquiring highly informative fingerprints. Three types of fingerprints were acquired (PDA, Total Ion Chromatograms (TIC), and MS fingerprints) which were used in the chemometric data analysis. Both unsupervised (i.e., Hierarchical Cluster Analysis (HCA)) and supervised techniques (i.e., Classification and Regression Tree (CART) and Partial Least Squares - Discriminant Analysis (PLS-DA)) were applied. The aim was to perform an in-depth study of the samples, thereby exploring potential patterns present in the data. HCA was able to generate a clustering which was mainly defined by chemical compounds detected in the samples, i.e., sibutramine, phenolphthalein and amfepramone. PLS-DA generated the best diagnostic models for both PDA and TIC fingerprints, characterized by correct classification rates of external validation of 85% and 80%, respectively. For the MS fingerprints, the best model was obtained by CART (65% correct classification rate of external validation). Despite a lower correct classification rate, exploration of the concerned misclassifications revealed that the MS fingerprints proved to be superior since even very low concentrations of sibutramine could be detected. This study shows that reliable chemometric models can be obtained, based on the presence of prohibited chemical substances, which allow high-throughput data analysis of such samples. Moreover, they generate a prime notion of potential threat to a patient's health posed by these kinds of slimming aids. Copyright © 2016 John Wiley & Sons, Ltd.

  15. Abundance-based Classifier for the Prediction of Mass Spectrometric Peptide Detectability Upon Enrichment (PPA)*

    PubMed Central

    Muntel, Jan; Boswell, Sarah A.; Tang, Shaojun; Ahmed, Saima; Wapinski, Ilan; Foley, Greg; Steen, Hanno; Springer, Michael

    2015-01-01

    The function of a large percentage of proteins is modulated by post-translational modifications (PTMs). Currently, mass spectrometry (MS) is the only proteome-wide technology that can identify PTMs. Unfortunately, the inability to detect a PTM by MS is not proof that the modification is not present. The detectability of peptides varies significantly making MS potentially blind to a large fraction of peptides. Learning from published algorithms that generally focus on predicting the most detectable peptides we developed a tool that incorporates protein abundance into the peptide prediction algorithm with the aim to determine the detectability of every peptide within a protein. We tested our tool, “Peptide Prediction with Abundance” (PPA), on in-house acquired as well as published data sets from other groups acquired on different instrument platforms. Incorporation of protein abundance into the prediction allows us to assess not only the detectability of all peptides but also whether a peptide of interest is likely to become detectable upon enrichment. We validated the ability of our tool to predict changes in protein detectability with a dilution series of 31 purified proteins at several different concentrations. PPA predicted the concentration dependent peptide detectability in 78% of the cases correctly, demonstrating its utility for predicting the protein enrichment needed to observe a peptide of interest in targeted experiments. This is especially important in the analysis of PTMs. PPA is available as a web-based or executable package that can work with generally applicable defaults or retrained from a pilot MS data set. PMID:25473088

  16. Lung cancer detection by proton transfer reaction mass-spectrometric analysis of human breath gas

    NASA Astrophysics Data System (ADS)

    Wehinger, Andreas; Schmid, Alex; Mechtcheriakov, Sergei; Ledochowski, Maximilian; Grabmer, Christoph; Gastl, Guenther A.; Amann, Anton

    2007-08-01

    Background Determination of the diagnostic usefulness of proton transfer reaction mass spectrometry (PTR-MS) for detecting primary lung cancer through analysis of volatile organic compounds (VOCs) in exhaled human breath was demonstrated in this investigation. Unlike, for example, gas-chromatographic analyses, PTR-MS can be used without time-consuming preconcentration of the gas samples.Methods By means of PTR-MS, exhaled breath samples from primary lung cancer patients (n = 17) were analyzed and compared with both an overall control collective (controls total, n = 170) and three sub-collectives: hospital personnel (controls hospital, n = 35), age-matched persons (controls age, n = 25), and smokers (controls s, n = 60), respectively.Results Among the VOCs present at reasonably high concentrations, the ones leading to the product ion at m/z = 31 (VOC-31, tentatively protonated formaldehyde) and m/z = 43 (VOC-43, tentatively a fragment of protonated iso-propanol), were found at significantly higher concentrations in the breath gas of the primary lung cancer patients as compared to the healthy controls at the following median concentrations (with interquartile distance, iqr): For VOC-31 the median concentrations were 7.0 ppb (iqr, 15.5 ppb) versus 3.0 ppb (iqr, 1.9 ppb) with P < 10-4. For VOC-43 the median concentrations were 244.1 ppb (iqr, 236.2 ppb) versus 94.1 ppb (iqr, 55.2 ppb) with P < 10-6. The discriminative power between the two collectives was further assessed by ROC-curves obtained upon variation of the chosen threshold concentration and by Fisher's Quadratic Discriminant Method.Conclusions Within the limits of pilot study, VOC-31 and -43 were found to best discriminate between exhaled breath of primary lung cancer cases and healthy controls. Simple and time-saving breath gas analysis by PTR-MS makes this method attractive for a larger clinical evaluation. It may become a new valuable tool for diagnosing primary lung cancer.

  17. Oxidative lipidomics of hyperoxic acute lung injury: mass spectrometric characterization of cardiolipin and phosphatidylserine peroxidation

    PubMed Central

    Tyurin, Vladimir A.; Kaynar, A. Murat; Kapralova, Valentyna I.; Wasserloos, Karla; Li, Jin; Mosher, Mackenzie; Wright, Lindsay; Wipf, Peter; Watkins, Simon; Pitt, Bruce R.; Kagan, Valerian E.

    2010-01-01

    Reactive oxygen species have been shown to play a significant role in hyperoxia-induced acute lung injury, in part, by inducing apoptosis of pulmonary endothelium. However, the signaling roles of phospholipid oxidation products in pulmonary endothelial apoptosis have not been studied. Using an oxidative lipidomics approach, we identified individual molecular species of phospholipids involved in the apoptosis-associated peroxidation process in a hyperoxic lung. C57BL/6 mice were killed 72 h after exposure to hyperoxia (100% oxygen). We found that hyperoxia-induced apoptosis (documented by activation of caspase-3 and -7 and histochemical terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling staining of pulmonary endothelium) was accompanied by nonrandom oxidation of pulmonary lipids. Two anionic phospholipids, mitochondria-specific cardiolipin (CL) and extramitochondrial phosphatidylserine (PS), were the two major oxidized phospholipids in hyperoxic lung. Using electrospray ionization mass spectrometry, we identified several oxygenation products in CL and PS. Quantitative assessments revealed a significant decrease of CL and PS molecular species containing C18:2, C20:4, C22:5, and C22:6 fatty acids. Similarly, exposure of mouse pulmonary endothelial cells (MLEC) to hyperoxia (95% oxygen; 72 h) resulted in activation of caspase-3 and -7 and significantly decreased the content of CL molecular species containing C18:2 and C20:4 as well as PS molecular species containing C22:5 and C22:6. Oxygenated molecular species were found in the same two anionic phospholipids, CL and PS, in MLEC exposed to hyperoxia. Treatment of MLEC with a mitochondria-targeted radical scavenger, a conjugate of hemi-gramicidin S with nitroxide, XJB-5-131, resulted in significantly lower oxidation of both CL and PS and a decrease in hyperoxia-induced changes in caspase-3 and -7 activation. We speculate that cytochrome c driven oxidation of CL and PS is associated with the signaling

  18. Mass spectrometric analyses of phospholipids in the S334ter-3 rat model of retinal degeneration

    PubMed Central

    Chen, Caroline Y.; Lam, Byron L.; Bhattacharya, Sanjoy K.

    2014-01-01

    Purpose The purpose of this study was to profile the endogenous phospholipid species in the retinal tissue of the S334ter-3 rat model of retinal degeneration. Retinal tissue was collected from S334ter-3 rats at postnatal day (P) 20, P30, and P60, while control retinal samples were collected from Sprague-Dawley (SD) rats at the same time points for comparison. Methods Lipids were extracted using the Bligh and Dyer method, and resuspended in an acetonitrile/isopropanol (1:1) solution. For lipid analyses, a positive ion–mode precursor ion scan (PIS) was used for phosphatidylcholine (PC; product m/z of 184), a negative ion–mode neutral loss scan (NLS) was used for phosphatidylserine (PS; product m/z of 87.1), and a negative ion–mode PIS was used for phosphatidylinositol (PI; product m/z of 241) and phosphatidylethanolamine (PE; product m/z of 196); the analyses were carried out using a TSQ Quantum Access Max mass spectrometer. The samples were directly infused with a Triversa Nanomate using 1.6 kV and 0.4 psi of pressure for the positive ion mode, and 1.3 kV and 0.6 psi of pressure for the negative ion mode, and scanned for 2 min between 200 m/z and 1000 m/z. Ratiometric quantification was performed using quantitative standards for each lipid class. Results The comparative profiles of PC, PE, PS, and PI between S334ter-3 and control rats showed that there were several lipid species common to both groups, as well as several that were unique to the S334ter-3 group and vice versa. Conclusions It was found that the proportions of PC and PS were higher in the control retina compared to S334ter-3, and that the proportions of PE and PI were higher in the S334ter-3 retina compared to control. PMID:25489232

  19. Mass spectrometric characterisation and quantitation of selected low molecular mass compounds from the venom of Haplopelma lividum (Theraphosidae).

    PubMed

    Moore, Sara; Smyth, W Franklin; Gault, Victor A; O'Kane, Edmund; McClean, Stephen

    2009-06-01

    Arachnid venoms present a diverse and complex matrix for investigation, with their latent potential for innovative drug and pesticide design largely unrealised. The characterisation and quantification of selected low molecular mass compounds isolated from the crude venom of the Cobalt blue tarantula (Haplopelma lividum) were the objectives of this study. Fractionation of the crude venom was performed using reversed-phase high-performance liquid chromatography, with compound identification using both electrospray ionisation ion trap mass spectrometry and quadrupole time-of-flight mass spectrometry. Four compounds were identified, and quantification on a percentage dry weight basis was achieved by liquid chromatography/electrospray ionisation tandem mass spectrometry based on the formation of their corresponding product ions. Of these the most abundant component was glutamic acid, present at a level of 0.97%. Histamine and adenosine were detected at 0.14% and 0.10% dry weight, respectively, with the polyamine spermine noted in trace amounts at 0.002%. The limits of detection and quantification were established for each of the identified components. The fragmentation profile for histamine has also been proposed.

  20. mMass 3: a cross-platform software environment for precise analysis of mass spectrometric data.

    PubMed

    Strohalm, Martin; Kavan, Daniel; Novák, Petr; Volný, Michael; Havlícek, Vladimír

    2010-06-01

    While tools for the automated analysis of MS and LC-MS/MS data are continuously improving, it is still often the case that at the end of an experiment, the mass spectrometrist will spend time carefully examining individual spectra. Current software support is mostly provided only by the instrument vendors, and the available software tools are often instrument-dependent. Here we present a new generation of mMass, a cross-platform environment for the precise analysis of individual mass spectra. The software covers a wide range of processing tasks such as import from various data formats, smoothing, baseline correction, peak picking, deisotoping, charge determination, and recalibration. Functions presented in the earlier versions such as in silico digestion and fragmentation were redesigned and improved. In addition to Mascot, an interface for ProFound has been implemented. A specific tool is available for isotopic pattern modeling to enable precise data validation. The largest available lipid database (from the LIPID MAPS Consortium) has been incorporated and together with the new compound search tool lipids can be rapidly identified. In addition, the user can define custom libraries of compounds and use them analogously. The new version of mMass is based on a stand-alone Python library, which provides the basic functionality for data processing and interpretation. This library can serve as a good starting point for other developers in their projects. Binary distributions of mMass, its source code, a detailed user's guide, and video tutorials are freely available from www.mmass.org .

  1. IGE RECEPTOR-MEDIATED ALTERATION OF MEMBRANE-CYTOSKELETAL INTERACTIONS REVEALED BY MASS SPECTROMETRIC ANALYSIS OF DETERGENT-RESISTANT MEMBRANES†

    PubMed Central

    Han, Xuemei; Smith, Norah L.; Sil, Dwaipayan; Holowka, David A.; McLafferty, Fred W.; Baird, Barbara A.

    2009-01-01

    these changes are independent of fatty acid chain length. Our mass spectrometric analyses provide a detailed accounting of receptor-activated alterations in the plasma membrane that are regulated by the actin cytoskeleton. PMID:19496615

  2. Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Samaras, Stefanos; Nicolae, Doina; Böckmann, Christine; Vasilescu, Jeni; Binietoglou, Ioannis; Labzovskii, Lev; Toanca, Florica; Papayannis, Alexandros

    2015-10-01

    In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns.

  3. DEVELOPMENTS IN DIRECT THERMAL EXTRACTION GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF FINE AEROSOLS

    EPA Science Inventory

    This examines thermal extraction gas chromatography-mass spectrometry (TE/GC/MS) applied to aerosols collected on filters. Several different TE/GC/MS systems as a group have speciated hundreds of individual organic constituents in ambient fine aerosols. Molecular marker source ap...

  4. Aerosol properties and radiative forcing for three air masses transported in Summer 2011 to Sopot, Poland

    NASA Astrophysics Data System (ADS)

    Rozwadowska, Anna; Stachlewska, Iwona S.; Makuch, P.; Markowicz, K. M.; Petelski, T.; Strzałkowska, A.; Zieliński, T.

    2013-05-01

    Properties of atmospheric aerosols and solar radiation reaching the Earth's surface were measured during Summer 2011 in Sopot, Poland. Three cloudless days, characterized by different directions of incoming air-flows, which are typical transport pathways to Sopot, were used to estimate a radiative forcing due to aerosols present in each air mass.

  5. Chemical composition and characteristics of ambient aerosols and rainwater residues during Indian summer monsoon: Insight from aerosol mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, Sachchida N.

    2016-07-01

    Real time composition of non-refractory submicron aerosol (NR-PM1) is measured via Aerosol mass spectrometer (AMS) for the first time during Indian summer monsoon at Kanpur, a polluted urban location located at the heart of Indo Gangetic Plain (IGP). Submicron aerosols are found to be dominated by organics followed by nitrate. Source apportionment of organic aerosols (OA) via positive matrix factorization (PMF) revealed several types of secondary/oxidized and primary organic aerosols. On average, OA are completely dominated by oxidized OA with a very little contribution from biomass burning OA. During rain events, PM1 concentration is decreased almost by 60%, but its composition remains nearly the same. Oxidized OA showed slightly more decrease than primary OAs, probably due to their higher hygroscopicity. The presence of organo nitrates (ON) is also detected in ambient aerosols. Apart from real-time sampling, collected fog and rainwater samples were also analyzed via AMS in offline mode and in the ICP-OES (Inductively coupled plasma - Optical emission spectrometry) for elements. The presence of sea salt, organo nitrates and sulfates has been observed. Rainwater residues are also dominated by organics but their O/C ratios are 15-20% lower than the observed values for ambient OA. Alkali metals such as Ca, Na, K are found to be most abundant in the rainwater followed by Zn. Rainwater residues are also found to be much less oxidized than the aerosols present inside the fog water, indicating presence of less oxidized organics. These findings indicate that rain can act as an effective scavenger of different types of pollutants even for submicron particle range. Rainwater residues also contain organo sulfates which indicate that some portion of the dissolved aerosols has undergone aqueous processing, possibly inside the cloud. Highly oxidized and possibly hygroscopic OA during monsoon period compared to other seasons (winter, post monsoon), indicates that they can act

  6. Ultrahigh mass resolution and accurate mass measurements as a tool to characterize oligomers in secondary organic aerosols.

    PubMed

    Reinhardt, Alain; Emmenegger, Christian; Gerrits, Bertran; Panse, Christian; Dommen, Josef; Baltensperger, Urs; Zenobi, Renato; Kalberer, Markus

    2007-06-01

    Organic aerosols are a major fraction, often more than 50%, of the total atmospheric aerosol mass. The chemical composition of the total organic aerosol mass is poorly understood, although hundreds of compounds have been identified in the literature. High molecular weight compounds have recently gained much attention because this class of compounds potentially represents a major fraction of the unexplained organic aerosol mass. Here we analyze secondary organic aerosols, generated in a smog chamber from alpha-pinene ozonolysis with ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). About 450 compounds are detected in the mass range of m/z 200-700. The mass spectrum is clearly divided into a low molecular weight range (monomer) and a high molecular weight range, where dimers and trimers are distinguishable. Using the Kendrick mass analysis, the elemental composition of about 60% of all peaks could be determined throughout the whole mass range. Most compounds have high O:C ratios between 0.4 and 0.6. Small compounds (i.e., monomers) have a higher maximum O:C ratio than dimers and trimers, suggesting that condensation reactions with, for example, the loss of water are important in the oligomer formation process. A program developed in-house was used to determine exact mass differences between peaks in the monomer, dimer, and trimer mass range to identify potential monomer building blocks, which form the co-oligomers observed in the mass spectrum. A majority of the peaks measured in the low mass region of the spectrum (m/z < 300) is also found in the calculated results. For the first time the elemental composition of the majority of peaks over a wide mass range was determined using advanced data analysis methods for the analysis of ultra-high-resolution MS data. Possible oligomer formation mechanisms in secondary organic aerosols were investigated.

  7. Secondary Aerosol Formation in the planetary boundary layer observed by aerosol mass spectrometry on a Zeppelin NT

    NASA Astrophysics Data System (ADS)

    Rubach, Florian; Trimborn, Achim; Mentel, Thomas; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL). In combination with the high scientific payload of more than 1 ton, the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due its lifetime of up to several days secondaray aerosol at a certain location can result from local production or from transport processes. For aerosol measurements on a Zeppelin, a High-Resolution Time-of-Flight Aerosol Mass spectrometer (DeCarlo et al, 2006) was adapted to the requirements posed by an airborne platform. A weight reduction of over 20 % compared to the commercial instrument was achieved, while space occupation and footprint were each reduced by over 25 %. Within the PEGASOS project, the instrument was part of 10 measurement flight days over the course of seven weeks. Three flights were starting from Rotterdam, NL, seven flights were starting from Ozzano in the Po Valley, IT. Flight patterns included vertical profiles to study the dynamics of the PBL and cross sections through regions of interest to shed light on local production and transport processes. Analysis of data from transects between the Apennin and San Pietro Capofiume in terms of "residence time of air masses in the Po valley" indicates that aerosol nitrate has only local sources while aerosol sulfate is dominated by transport. The organic aerosol component has significant contributions of both processes. The local prodcution yields are commensurable with imultaneously observed precursor concentrations and oxidant levels. The PEGASOS project is funded by the European Commission under the Framework Programme 7 (FP7-ENV-2010-265148). DeCarlo, P.F. et al (2006), Anal. Chem., 78, 8281-8289.

  8. Advances in mass spectrometric characterization of naphthenic acids fraction compounds in oil sands environmental samples and crude oil--A review.

    PubMed

    Headley, John V; Peru, Kerry M; Barrow, Mark P

    2016-01-01

    There has been a recent surge in the development of mass spectrometric methods for detailed characterization of naphthenic acid fraction compounds (all C(c)H(h)N(n)O(o)S(s), species, including heteroatomic and aromatic components in the acid-extractable fraction) in environmental samples. This surge is driven by the increased activity in oil sands environmental monitoring programs in Canada, the exponential increase in research studies on the isolation and toxicity identification of components in oil sands process water (OSPW), and the analytical requirements for development of technologies for treatment of OSPW. There has been additional impetus due to the parallel studies to control corrosion from naphthenic acids during the mining and refining of heavy bitumen and crude oils. As a result, a range of new mass spectrometry tools have been introduced since our last major review of this topic in 2009. Of particular significance are the developments of combined mass spectrometric methods that incorporate technologies such as gas chromatography, liquid chromatography, and ion mobility. There has been additional progress with respect to improved visualization methods for petroleomics and oil sands environmental forensics. For comprehensive coverage and more reliable characterization of samples, an approach based on multiple-methods that employ two or more ionization modes is recommended. On-line or off-line fractionation of isolated extracts, with or without derivatization, might also be used prior to mass spectrometric analyses. Individual ionization methods have their associated strengths and weaknesses, including biases, and thus dependence upon a single ionization method is potentially misleading. There is also a growing trend to not rely solely on low-resolution mass spectrometric methods (<20,000 resolving power at m/z 200) for characterization of complex samples. Future research is anticipated to focus upon (i) structural elucidation of components to determine

  9. Liquid chromatography tandem mass spectrometric quantitation of sulfamethazine and its metabolites: direct analysis of swine urine by triple quadrupole and by ion trap mass spectrometry.

    PubMed

    Bartolucci, G; Pieraccini, G; Villanelli, F; Moneti, G; Triolo, A

    2000-01-01

    This work describes a new method for the quantitation of trace amounts of sulfamethazine (SMZ) and its main metabolite, N4-acetylsulfamethazine (Ac-SMZ), in swine urine, using high-performance liquid chromatography (HPLC) tandem mass spectrometric analysis of crude urine after addition of internal standard and simple dilution with water. The aim was to determine whether residues of this sulfamidic drug, normally administered to swine in order to prevent infectious diseases, were present in urine at levels lower than those permitted by regulatory authorities before human consumption (EU Project SMT, contract number CT 96-2092). A 10 microL volume of diluted urine was injected into a very short, narrow-bore chromatographic column (Zorbax SB-C18 2.1 i. d. x30 mm length, 3.5 microm pore size). Elution of the analytes of interest was achieved in less than seven minutes using a rapid gradient (from 20 to 80% methanol in 3 minutes). Either a PE Sciex API 365 triple quadrupole (QqQ), operated in the selected reaction monitoring (SRM) mode, or a Finnigan LCQ ion trap (IT) mass spectrometer, operated in narrow-range product ion scan, was used as the final detector. Electrospray (ESI) was used as the ionization technique. A comparison of the two tandem mass spectrometers was performed by analyzing the same set of test samples, at three concentration levels, on three different days. Linearity of responses of the calibration standards, intra- and inter-assay precision of the samples, specificity and limits of detection were evaluated for both systems. Both the QqQ and the IT instrument was suitable for rapid, sensitive and specific determination of the analytes, although the overall performance of the QqQ was slightly superior in terms of linearity, precision and sensitivity.

  10. Evaluating Simulations of Primary Anthropogenic and Biomass Burning Organic Aerosols using Aerosol Mass Spectrometer Data and Positive Matrix Factorization Analysis

    NASA Astrophysics Data System (ADS)

    Fast, J.; Aiken, A.; Alexander, L.; Canagaratna, M.; Decarlo, P.; Herndon, S.; Jimenez, J.; Kleinman, L.; Ochoa, C.; Onasch, T.; Song, C.; Wiedinmyer, C.; Yu, X.; Zaveri, R.

    2008-12-01

    Most model predictions of organic matter are currently underestimated because the processes contributing to secondary organic aerosol (SOA) formation and transformation are not well understood. Since research associated with developing a better framework to improve the representation of specific gas-to-particle partitioning processes controlling SOA based on new measurements and theoretical relationships is on- going, this study seeks to determine whether 3-D models can adequately predict concentrations of primary organic aerosols (POA). If one assumes POA is non-volatile, then errors in POA predictions will results from uncertainties in the emission inventories and errors in transport and mixing processes. The WRF-chem model is used to predict POA in the vicinity of Mexico City during the 2006 MILAGRO field campaign. Particulate matter emission rates were obtained from urban and regional Mexican emission inventories and from biomass burning estimates derived from MODIS "hotspot" and vegetation databases. Organic aerosol predictions are evaluated using data from Aerodyne Aerosol Mass Spectrometer (AMS) instruments deployed at four ground sites and on two research aircraft and from Sunset Laboratory OCEC instruments deployed at two ground sites. Positive Matrix Factorization (PMF) has recently been applied to derive components of organic aerosols including: hydrocarbon-like organic aerosol (HOA), oxidized organic aerosol (OOA), and biomass burning organic aerosols (BBOA). The temporal variation of HOA is often similar to primary emissions of other species in urban areas. PMF analysis is currently available for three of the ground sites and for some of the aircraft flights. We found that the predicted POA was consistently lower than the measured organic matter at the ground sites, which is consistent with the expectation that SOA should be a large fraction of the total organic aerosol mass. A much better agreement was found when predicted POA was compared with HOA

  11. Formation of iron complexs from trifluoroacetic acid based liquid chromatography mobile phases as interference ions in liquid chromatography/electrospray ionization mass spectrometric analysis

    SciTech Connect

    Shukla, Anil K.; Zhang, Rui; Orton, Daniel J.; Zhao, Rui; Clauss, Therese RW; Moore, Ronald J.; Smith, Richard D.

    2011-05-30

    Two unexpected singly charged ions at m/z 1103 and 944 have been observed in mass spectra obtained from electrospray ionization-mass spectrometric analysis of liquid chromatography effluents with mobile phases containing trifluoroacetic acid. Accurate mass measurement and tandem mass spectrometry studies revealed that these two ions are not due to any contamination from solvents and chemicals used for mobile and stationary phases or from the laboratory atmospheric environment. Instead these ions are clusters of trifluoroacetic acid formed in association with acetonitrile, water and iron from the stainless steel union used to connect the column with the electrospray tip and to apply high voltage; the molecular formulae are Fe+((OH)(H2O)2)9(CF3COOH)5 and Fe+((OH)(H2O)2)6 (CF3COOH)5.

  12. Unraveling the Complexity of Atmospheric Aerosol: Insights from Ultrahigh Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Mazzoleni, Lynn R.; Zhao, Yunzhu; Samburova, Vera; Gannet Hallar, A.; Lowenthal, Douglas

    2016-04-01

    Atmospheric aerosol organic matter (AOM) is a complex mixture of thousands of organic compounds, which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of AOM is needed to evaluate the effect of aerosol composition upon aerosol physical properties. Products of gas, aqueous and particle phase reactions contribute to the aerosol organic mass. Thus, ambient aerosols carry a complex array of AOM components with variable chemical signatures depending upon its origin and aerosol life-cycle processes. In this work, ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize ambient aerosol AOM collected at the Storm Peak Laboratory (3210 m a.s.l.) near Steamboat Springs, CO. Thousands of molecular formulas were assigned in the mass range of m/z 100-800 after negative-ion electrospray ionization. Using multivariate statistical analysis, correlations between the site meteorological conditions and specific molecular compositions were identified. For example, days with strong UV radiation and high temperature were found to contain large numbers of biogenic SOA molecular formulas. Similarly, days with high relative humidity and high sulfate concentrations were found to contain many sulfur-containing compounds, suggesting their aqueous phase formation.

  13. [Optimization of the solid-phase extraction procedure for the screening of the medicinal and narcotic substances in the blood by gas chromatography with mass-spectrometric detection].

    PubMed

    Kataev, S S; Dvorskaya, O N; Krokhin, I P

    2017-01-01

    This paper was designed to describe the application of the method for solid-phase extraction of the medicinal and narcotic substances having different physicochemical composition by gas chromatography with mass-spectrometric detection (GC-MS) for the purpose of their screening in the blood. The solid-phase extraction technique was optimized by means of the Box-Behnken modeling with the evaluation of the influence on the effectiveness of extraction of various factors including pH of the buffer solution, eluent composition, the type and the volume of the solutions used to wash the sorbent.

  14. Determination of tetrodotoxin and its analogs in the puffer fish Takifugu oblongus from Bangladesh by hydrophilic interaction chromatography and mass-spectrometric detection.

    PubMed

    Diener, Marc; Christian, Bernd; Ahmed, M Sagir; Luckas, Bernd

    2007-11-01

    Tetrodotoxin (TTX) and its analogs (TTXs), widely distributed among marine as well as terrestrial animals, induce dangerous intoxications. These highly potential toxins are also known as the causative agent of puffer fish poisoning. A newly developed highly sensitive method for determination of TTXs based on hydrophilic interaction chromatography and mass-spectrometric detection is presented. TTX, anhydrotetrodotoxin, 11-deoxytetrodotoxin and trideoxytetrodotoxin were determined in separated tissues of Bangladeshi marine puffers, Takifugu oblongus. TTX was predominant in skin, muscle and liver, whereas trideoxytetrodotoxin preponderated in the ovary. The toxicity of the various tissues was determined by a mouse bioassay.

  15. Mass-spectrometric characterization of phospholipids and their primary peroxidation products in rat cortical neurons during staurosporine-induced apoptosis

    PubMed Central

    Tyurin, Vladimir A.; Tyurina, Yulia Y.; Feng, Weihong; Mnuskin, Alexandra; Jiang, Jianfei; Tang, Minke; Zhang, Xiaojing; Zhao, Qing; Kochanek, Patrick M.; Clark, Robert S. B.; Bayır, Hulya; Kagan, Valerian E.

    2009-01-01

    The molecular diversity of phospholipids is essential for their structural and signaling functions in cell membranes. In the current work, we present, the results of mass spectrometric characterization of individual molecular species in major classes of phospholipids -phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylserine (PtdSer), phosphatidylinositol (PtdIns), sphingomyelin (CerPCho), and cardiolipin (Ptd2Gro) - and their oxidation products during apoptosis induced in neurons by staurosporine (STS). The diversity of molecular species of phospholipids in rat cortical neurons followed the order Ptd2Gro > PtdEtn ≫ PtdCho ≫ PtdSer > PtdIns > CerPCho. The number of polyunsaturated oxidizable species decreased in the order Ptd2Gro ≫ PtdEtn > PtdCho > PtdSer > PtdIns > CerPCho. Thus a relatively minor class of phospholipids, Ptd2Gro, was represented in cortical neurons by the greatest variety of both total and peroxidizable molecular species. Quantitative fluorescence HPLC analysis employed to assess the oxidation of different classes of phospholipids in neuronal cells during intrinsic apoptosis induced by staurosporine (STS) revealed that three anionic phospholipids — Ptd2Gro ≫ PtdSer > PtdIns — underwent robust oxidation. No significant oxidation in the most dominant phospholipid classes – PtdCho and PtdEtn – was detected. MS-studies revealed the presence of hydroxy-, hydroperoxy- as well as hydroxy-/hydroperoxy-species of Ptd2Gro, PtdSer, and PtdIns. Experiments in model systems where total cortex Ptd2Gro and PtdSer fractions were incubated in the presence of cytochrome c (cyt c) and H2O2, confirmed that molecular identities of the products formed were similar to the ones generated during STS-induced neuronal apoptosis. The temporal sequence of biomarkers of STS induced apoptosis and phospholipid peroxidation combined with recently demonstrated redox catalytic properties of cyt c realized through its interactions with Ptd2

  16. MALDI-mass spectrometric imaging revealing hypoxia-driven lipids and proteins in a breast tumor model

    SciTech Connect

    Lu, Jiang; Chughtai, Kamila; Purvine, Samuel O.; Bhujwalla, Zaver M.; Raman, Venu; Pasa-Tolic, Ljiljana; Heeren, Ronald M.; Glunde, Kristine

    2015-06-16

    Hypoxic areas are a common feature of rapidly growing malignant tumors and their metastases, and are typically spatially heterogeneous. Hypoxia has a strong impact on tumor cell biology and contributes to tumor progression in multiple ways. To date, only a few molecular key players in tumor hypoxia, such as for example hypoxia-inducible factor-1 (HIF-1), have been discovered. The distribution of biomolecules is frequently heterogeneous in the tumor volume, and may be driven by hypoxia and HIF-1α. Understanding the spatially heterogeneous hypoxic response of tumors is critical. Mass spectrometric imaging (MSI) provides a unique way of imaging biomolecular distributions in tissue sections with high spectral and spatial resolution. In this paper, breast tumor xenografts grown from MDA-MB-231-HRE-tdTomato cells, with a red fluorescent tdTomato protein construct under the control of a hypoxia response element (HRE)-containing promoter driven by HIF-1α, were used to detect the spatial distribution of hypoxic regions. We elucidated the 3D spatial relationship between hypoxic regions and the localization of small molecules, metabolites, lipids, and proteins by using principal component analysis – linear discriminant analysis (PCA-LDA) on 3D rendered MSI volume data from MDA-MB-231-HRE-tdTomato breast tumor xenografts. In this study we identified hypoxia-regulated proteins active in several distinct pathways such as glucose metabolism, regulation of actin cytoskeleton, protein folding, translation/ribosome, splicesome, the PI3K-Akt signaling pathway, hemoglobin chaperone, protein processing in endoplasmic reticulum, detoxification of reactive oxygen species, aurora B signaling/apoptotic execution phase, the RAS signaling pathway, the FAS signaling pathway/caspase cascade in apoptosis and telomere stress induced senescence. In parallel we also identified co-localization of hypoxic regions and various lipid species such as PC(16:0/18:1), PC(16:0/18:2), PC(18:0/18:1), PC

  17. Fractal morphology, imaging and mass spectrometry of single aerosol particles in flight (CXIDB ID 16)

    SciTech Connect

    Loh, N. Duane

    2012-06-20

    This deposition includes the aerosol diffraction images used for phasing, fractal morphology, and time-of-flight mass spectrometry. Files in this deposition are ordered in subdirectories that reflect the specifics.

  18. On the implications of aerosol liquid water and phase separation for organic aerosol mass

    NASA Astrophysics Data System (ADS)

    Pye, Havala O. T.; Murphy, Benjamin N.; Xu, Lu; Ng, Nga L.; Carlton, Annmarie G.; Guo, Hongyu; Weber, Rodney; Vasilakos, Petros; Wyat Appel, K.; Hapsari Budisulistiorini, Sri; Surratt, Jason D.; Nenes, Athanasios; Hu, Weiwei; Jimenez, Jose L.; Isaacman-VanWertz, Gabriel; Misztal, Pawel K.; Goldstein, Allen H.

    2017-01-01

    Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to organic carbon (OM / OC) ratios are high such that separation relative humidities (SRH) are below the ambient relative humidity (RH). As OM / OC ratios in the SE US are often between 1.8 and 2.2, organic aerosol experiences both mixing with inorganic water and separation from it. Regional chemical transport model simulations including inorganic water (but excluding water uptake by organic compounds) in the partitioning medium for secondary organic aerosol (SOA) when RH > SRH led to increased SOA concentrations, particularly at night. Water uptake to the organic phase resulted in even greater SOA concentrations as a result of a positive feedback in which water uptake increased SOA, which further increased aerosol water and organic aerosol. Aerosol properties, such as the OM / OC and hygroscopicity parameter (κorg), were captured well by the model compared with measurements during the Southern Oxidant and Aerosol Study (SOAS) 2013. Organic nitrates from monoterpene oxidation were predicted to be the least water-soluble semivolatile species in the model, but most biogenically derived semivolatile species in the Community Multiscale Air Quality (CMAQ) model were highly water soluble and expected to contribute to water-soluble organic carbon (WSOC). Organic aerosol and SOA precursors were abundant at night, but additional improvements in daytime organic aerosol are needed to close the model-measurement gap. When taking into account deviations from ideality, including both inorganic (when RH > SRH) and organic water in the organic partitioning medium reduced the mean bias in SOA for routine monitoring networks and improved model performance compared to observations from SOAS. Property updates from

  19. Combined electron transfer dissociation-collision-induced dissociation fragmentation in the mass spectrometric distinction of leucine, isoleucine, and hydroxyproline residues in Peptide natural products.

    PubMed

    Gupta, Kallol; Kumar, Mukesh; Chandrashekara, Krishnappa; Krishnan, Kozhalmannom S; Balaram, Padmanabhan

    2012-02-03

    Distinctions between isobaric residues have been a major challenge in mass spectrometric peptide sequencing. Here, we propose a methodology for distinction among isobaric leucine, isoleucine, and hydroxyproline, a commonly found post-translationally modified amino acid with a nominal mass of 113 Da, through a combined electron transfer dissociation-collision-induced dissociation approach. While the absence of c and z(•) ions, corresponding to the Yyy-Xxx (Xxx = Leu, Ile, or Hyp) segment, is indicative of the presence of hydroxyproline, loss of isopropyl (Δm = 43 Da) or ethyl radicals (Δm = 29 Da), through collisional activation of z radical ions, are characteristic of leucine or isoleucine, respectively. Radical migration processes permit distinctions even in cases where the specific z(•) ions, corresponding to the Yyy-Leu or -Ile segments, are absent or of low intensity. This tandem mass spectrometric (MS(n)) method has been successfully implemented in a liquid chromatography-MS(n) platform to determine the identity of 23 different isobaric residues from a mixture of five different peptides. The approach is convenient for distinction of isobaric residues from any crude peptide mixture, typically encountered in natural peptide libraries or proteomic analysis.

  20. Spectrometre de masse a ionisation Penning selective: Elimination des corrections necessaires a la determination du rapport isotopique de l'hydrogene

    NASA Astrophysics Data System (ADS)

    Letarte, Sylvain

    Dans le but d'ameliorer la precision avec laquelle le rapport isotopique de l'hydrogene peut etre determine, un spectrometre de masse a ionisation Penning a ete construit pour provoquer l'ionisation selective de l'hydrogene moleculaire et de l'hydrure de deuterium a partir d'un melange gazeux. L'utilisation d'atomes dans des etats d'excitation metastable s'est averee une solution adequate pour reponde a cette attente. L'emploi de l'helium, a l'interieur d'une source d'atomes metastables construit specifiquement pour ce travail, ne permet pas d'obtenir un spectre de masse compose uniquement des deux molecules d'interet. L'ionisation de ces dernieres provient de deux processus distincts, soient l'ionisation Penning et l'ionisation par bombardement electronique. Contrairement a l'helium, il a ete demontre que le neon metastable est un candidat ideal pour produire l'ionisation selective de type Penning. Le nombre d'ions produits est directement proportionnel au courant de la decharge electrique et de la pression d'operation de la source d'atomes metastables. Ces resultats demontrent le potentiel d'un tel spectrometre de masse pour ameliorer la precision a laquelle le rapport isotopique peut etre determine comparativement aux autres techniques existantes.

  1. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  2. New mass measurement method of aerosol particle using vibrating probe particle controlled by radiation pressure

    NASA Astrophysics Data System (ADS)

    Hariyama, Tatsuo; Takaya, Yasuhiro; Miyoshi, Takashi

    2005-11-01

    Aerosol particles with sub-micro meter size inhaled into respiratory systems cause serious damage to human body. In order to evaluate the health effects of the particles, classification methods of the particles with size and mass are needed. Several measurement methods of the particle size are established. However, conventional mass measurement methods are not enough to measure the particles with sub- pico gram. We propose a new mass measurement method of the aerosol particles based on laser trapping. In this method, an optically trapped silica particle is used as a measuring probe particle. The probe particle is trapped at a beam waist of the focused laser light and is forced to vibrate by deflecting the beam waist using AOD. The vibrating probe particle has a resonance frequency because it is governed by the spring-mass-damper system. When an aerosol particle is attached to the probe particle, the resonance frequency shifts according to the increase of the total mass. The mass of the aerosol particle can be measured from the shift of the resonance frequency. Experimentally, it is confirmed that the probe particle is governed by the spring-mass-damper system and has a resonance frequency. When a silica fine particle of 3pg in mass used as an aerosol particle is attached to the probe particle, the resonance frequency shift occurs as expected in the dynamic system and the fine particle mass can be measured based on the proposed method.

  3. Aerosol Composition in Los Angeles During the 2010 CalNex Campaign Studied by High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Hayes, P. L.; Ortega, A. M.; Cubison, M.; Hu, W.; Toohey, D. W.; Flynn, J. H.; Grossberg, N.; Lefer, B. L.; Alvarez, S.; Rappenglueck, B.; Allan, J. D.; McKeen, S. A.; Holloway, J. S.; Gilman, J. B.; Kuster, W. C.; Graus, M.; Warneke, C.; de Gouw, J. A.; Richter, R.; Hofer, J.; Prevot, A. S.; Jimenez, J. L.

    2010-12-01

    Submicron atmospheric aerosols impact climate and human health, but their sources and composition are poorly understood. To address this knowledge gap, high-resolution time-of-flight aerosol mass spectrometry (AMS) [DeCarlo et al. Anal. Chem. 2006] and other advanced instrumentation were deployed during the CalNex field campaign in May and June 2010 for 4 weeks to characterize the composition of aerosols in the Los Angeles area. Utilizing AMS, the concentrations for both organic and non-refractory inorganic (sulfate, nitrate, ammonium, chloride) submicron aerosols were quantified at the Caltech/Pasadena ground site 15 km NE of downtown Los Angeles. The total submicron mass concentration as well as the species concentrations measured by AMS compare well with other instruments. Nitrate aerosols appear to dominate in the cooler mornings, but their concentration is reduced in the afternoon when organic aerosols (OA) increase and dominate. The diurnal variations in concentration are strongly influenced by vertical dilution from the rising planetary boundary layer in the afternoon. Secondary organic aerosols (SOA) are an important fraction of submicron aerosols. To assess the concentrations of different OA components present at the site, positive matrix factorization (PMF) is used to analyze the field data. The major OA classes are oxygenated OA (OOA, a surrogate for total SOA), and hydrocarbon-like OA (HOA, a surrogate for primary combustion OA). Preliminary PMF analysis finds that OOA is consistently the largest type of OA present (~75% of the total OA concentration). This result suggests that the air mass over the site has undergone substantial chemical aging. The correlations between OOA and Ox (O3 + NO2) concentrations, as well as between HOA, CO and black carbon concentrations are strong and consistent with previous studies. AMS and 14C measurements are combined to determine the fractions of HOA and OOA from non-fossil vs. fossil sources. Using measurements of SOA

  4. Determination of aromatic tracer compounds for environmental tobacco smoke aerosol by two step laser mass spectrometry

    NASA Astrophysics Data System (ADS)

    Morrical, Brad D.; Zenobi, Renato

    Cigarette smoking is a major cause of indoor aerosol pollution. Determination of exposure to environmental tobacco smoke (ETS) aerosol is critical to understanding health effects. Sizing studies have shown that ETS has a size distribution that is efficiently deposited into the lungs and can therefore provide effective delivery of carcinogenic compounds into the human body. Two-step laser mass spectrometry is used to analyze aromatic compounds on aerosols collected from a smoking lobby. The determination and suitability of ETS tracers on aerosols is examined. Additionally, the transport of aerosol from the smoking lobby is examined to determine what effect deposition and dilution have on the mass spectrum observed. Results from the analysis of ETS, both from lobby samples and direct cigarette sampling, show that several unique peaks are present in the mass spectrum when compared to other combustion sources, such as automobiles and diesel trucks. In particular, ions at m/ z 118, 132, 146, and 160 are consistently present and are not found in other combustion sources. For the indoor environment, where chemical transformation is much less rapid than in the outdoor environment, these ions were found to be present as soon as the first smokers appeared and persisted over the course of the day. Aerosol samples taken in the morning prior to the presence of smokers in the lobby reveal the presence of skeletal PAHs, indicative of outdoor urban traffic aerosol penetration into the building.

  5. Chemical characterization of submicron aerosol particles during wintertime in a northwest city of China using an Aerodyne aerosol mass spectrometry.

    PubMed

    Zhang, Xinghua; Zhang, Yangmei; Sun, Junying; Yu, Yangchun; Canonaco, Francesco; Prévôt, Andre S H; Li, Gang

    2017-03-01

    An Aerodyne quadrupole aerosol mass spectrometry (Q-AMS) was utilized to measure the size-resolved chemical composition of non-refractory submicron particles (NR-PM1) from October 27 to December 3, 2014 at an urban site in Lanzhou, northwest China. The average NR-PM1 mass concentration was 37.3 μg m(-3) (ranging from 2.9 to 128.2 μg m(-3)) under an AMS collection efficiency of unity and was composed of organics (48.4%), sulfate (17.8%), nitrate (14.6%), ammonium (13.7%), and chloride (5.7%). Positive matrix factorization (PMF) with the multi-linear engine (ME-2) solver identified six organic aerosol (OA) factors, including hydrocarbon-like OA (HOA), coal combustion OA (CCOA), cooking-related OA (COA), biomass burning OA (BBOA) and two oxygenated OA (OOA1 and OOA2), which accounted for 8.5%, 20.2%, 18.6%, 12.4%, 17.8% and 22.5% of the total organics mass on average, respectively. Primary emissions were the major sources of fine particulate matter (PM) and played an important role in causing high chemically resolved PM pollution during wintertime in Lanzhou. Back trajectory analysis indicated that the long-range regional transport air mass from the westerly was the key factor that led to severe submicron aerosol pollution during wintertime in Lanzhou.

  6. Effect of Vaporizer Temperature on Ambient Non-Refractory Submicron Aerosol Composition and Mass Spectra Measured by the Aerosol Mass Spectrometer

    EPA Science Inventory

    Aerodyne Aerosol Mass Spectrometers (AMS) are routinely operated with a constant vaporizer temperature (Tvap) of 600oC in order to facilitate quantitative detection of non-refractory submicron (NR-PM1) species. By analogy with other thermal desorption instrument...

  7. Progress Toward a Global, EOS-Era Aerosol Air Mass Type Climatology

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2012-01-01

    The MISR and MODIS instruments aboard the NASA Earth Observing System's Terra Satellite have been collecting data containing information about the state of Earth's atmosphere and surface for over eleven years. Data from these instruments have been used to develop a global, monthly climatology of aerosol amount that is widely used as a constraint on climate models, including those used for the 2007 IPCC assessment report. The next frontier in assessing aerosol radiative forcing of climate is aerosol type, and in particular, the absorption properties of major aerosol air masses. This presentation will focus on the prospects for constraining aerosol type globally, and the steps we are taking to apply a combination of satellite and suborbital data to this challenge.

  8. OMI tropospheric NO2 air mass factors over South America: effects of biomass burning aerosols

    NASA Astrophysics Data System (ADS)

    Castellanos, P.; Boersma, K. F.; Torres, O.; de Haan, J. F.

    2015-03-01

    Biomass burning is an important and uncertain source of aerosols and NOx (NO + NO2) to the atmosphere. OMI observations of tropospheric NO2 are essential for characterizing this emissions source, but inaccuracies in the retrieval of NO2 tropospheric columns due to the radiative effects of aerosols, especially light-absorbing carbonaceous aerosols, are not well understood. It has been shown that the O2-O2 effective cloud fraction and pressure retrieval is sensitive to aerosol optical and physical properties, including aerosol optical depth (AOD). Aerosols implicitly influence the tropospheric air mass factor (AMF) calculations used in the NO2 retrieval through the effective cloud parameters used in the independent pixel approximation. In this work, we explicitly account for the effects of biomass burning aerosols in the tropospheric NO2 AMF calculation by including collocated aerosol extinction vertical profile observations from the CALIOP instrument, and aerosol optical depth (AOD) and single scattering albedo (SSA) retrieved by the OMI near-UV aerosol algorithm (OMAERUV) in the DISAMAR radiative transfer model for cloud-free scenes. Tropospheric AMFs calculated with DISAMAR were benchmarked against AMFs reported in the Dutch OMI NO2 (DOMINO) retrieval; the mean and standard deviation (SD) of the difference was 0.6 ± 8%. Averaged over three successive South American biomass burning seasons (2006-2008), the spatial correlation in the 500 nm AOD retrieved by OMI and the 532 nm AOD retrieved by CALIOP was 0.6, and 72% of the daily OMAERUV AOD observations were within 0.3 of the CALIOP observations. Overall, tropospheric AMFs calculated with observed aerosol parameters were on average 10% higher than AMFs calculated with effective cloud parameters. For effective cloud radiance fractions less than 30%, or effective cloud pressures greater than 800 hPa, the difference between tropospheric AMFs based on implicit and explicit aerosol parameters is on average 6 and 3

  9. Gas-phase CO2 subtraction for improved measurements of the organic aerosol mass concentration and oxidation degree by an aerosol mass spectrometer.

    PubMed

    Collier, S; Zhang, Q

    2013-12-17

    The Aerodyne aerosol mass spectrometer (AMS) has been widely used for real-time characterization of the size-resolved chemical composition of sub-micrometer aerosol particles. The first step in AMS sampling is the pre-concentration of aerosols while stripping away the gas-phase components, which contributes to the high sensitivity of this instrument. The strength of the instrument lies in particle phase measurement; however, ion signals generated from gas-phase species can influence the interpretation of the particle-phase chemistry data. Here, we present methods for subtracting the varying contributions of gas-phase carbon dioxide (CO2) in the AMS spectra of aerosol particles, which is critical for determining the mass concentration and oxygen-to-carbon (O/C) ratio of organic aerosol. This report gives details on the gaseous CO2 subtraction analysis performed on a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) data set acquired from sampling of fresh and diluted vehicle emissions. Three different methods were used: (1) collocated continuous gas-phase CO2 measurement coupled with periodic filter tests consisting of sampling the same particle-free air by the AMS and the CO2 analyzer, (2) positive matrix factorization (PMF) analysis to separate the gas- and particle-phase signals of CO2(+) at m/z 44, and (3) use of the particle time-of-flight (PTOF) size-resolved chemical information for separation of gas- and particle-phase signals at m/z 44. Our results indicate that these three different approaches yield internally consistent values for the gas/particle apportionment of m/z 44, but methods 2 and 3 require certain conditions to be met to yield reliable results. The methods presented are applicable to any situation where gas-phase components may influence the PM signal of interest.

  10. Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

    NASA Technical Reports Server (NTRS)

    DeCarlo, P. F.; Dunlea, E. J.; Kimmel, J. R.; Aiken, A. C.; Sueper, D.; Crounse, J.; Wennberg, P. O.; Emmons, L.; Shinozuka, Y.; Clarke, A.; Zhou, J.; Tomlinson, J.; Collins,D. R.; Knapp, D.; Weinheimer, A. J.; Montzka,D. D.; Campos,T.; Jimenez, J. L.

    2007-01-01

    The concentration, size, and composition of non-refractory submicron aerosol (NR-PM(sub l)) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM(sub l) mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 microg/cubic m (STP) ppm(exp -1). This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city

  11. Evolution of organic aerosol mass spectra upon heating: implications for OA phase and partitioning behavior

    SciTech Connect

    UC Davis; Cappa, Christopher D.; Wilson, Kevin R.

    2010-10-28

    Vacuum Ultraviolet (VUV) photoionization mass spectrometry has been used to measure the evolution of chemical composition for two distinct organic aerosol types as they are passed through a thermodenuder at different temperatures. The two organic aerosol types considered are primary lubricating oil (LO) aerosol and secondary aerosol from the alpha-pinene + O3 reaction (alphaP). The evolution of the VUV mass spectra for the two aerosol types with temperature are observed to differ dramatically. For LO particles, the spectra exhibit distinct changes with temperature in which the lower m/z peaks, corresponding to compounds with higher vapor pressures, disappear more rapidly than the high m/z peaks. In contrast, the alphaP aerosol spectrum is essentially unchanged by temperature even though the particles experience significant mass loss due to evaporation. The variations in the LO spectra are found to be quantitatively in agreement with expectations from absorptive partitioning theory whereas the alphaP spectra suggest that the evaporation of alphaP derived aerosol appears to not be governed by partitioning theory. We postulate that this difference arises from the alphaP particles existing as in a glassy state instead of having the expected liquid-like behavior. To reconcile these observations with decades of aerosol growth measurements, which indicate that OA formation is described by equilibrium partitioning, we present a conceptual model wherein the secondary OA is formed and then rapidly converted from an absorbing form to a non-absorbing form. The results suggest that although OA growth may be describable by equilibrium partitioning theory, the properties of organic aerosol once formed may differ significantly from the properties determined in the equilibrium framework.

  12. Chemical fingerprinting of Shexiang Baoxin Pill and simultaneous determination of its major constituents by HPLC with evaporative light scattering detection and electrospray mass spectrometric detection.

    PubMed

    Yan, Shi-Kai; Zhang, Wei-Dong; Liu, Run-Hui; Zhan, Yong-Cheng

    2006-07-01

    High-performance Liquid Chromatography (HPLC) with evaporative light scattered detection (ELSD) and electrospray ionization mass spectrometric detection (ESI-MS) was employed to establish chemical fingerprint of Shexiang Baoxin Pill (SBP) and to simultaneously determinate its seven major constituents, including cholic acid, deoxycholic acid, ursodeoxycholic acid, chenodeoxycholic acid, cinobufagin, recibufogenin, and ginsenoside Rb1. The analysis was performed on a C18 column with water-acetonitrile gradient elution, and the investigated constituents were authenticated by comparing their retention times and mass spectra with those of reference compounds. The proposed method was applied to analyze nine SBP samples and produced data with acceptable linearity, precision, stability and accuracy. Both the chemical fingerprints and quantification data were used to evaluate the quality of various SBP products. The proposed method allows obtaining chemical fingerprint and quantification of multi-components in one run, and therefore can be readily utilized as a comprehensive quality control approach for traditional Chinese medicine.

  13. Gas chromatography/mass spectrometric analysis of methyl esters of N,N-dialkylaminoethane-2-sulfonic acids for verification of the Chemical Weapons Convention.

    PubMed

    Pardasani, Deepak; Gupta, Arvinda K; Palit, Meehir; Shakya, Purushottam; Kanaujia, Pankaj K; Sekhar, K; Dubey, Devendra K

    2005-01-01

    This paper describes the synthesis and gas chromatography/electron ionization mass spectrometric (GC/EI-MS) analysis of methyl esters of N,N-dialkylaminoethane-2-sulfonic acids (DAESAs). These sulfonic acids are important environmental signatures of nerve agent VX and its toxic analogues, hence GC/EI-MS analysis of their methyl esters is of paramount importance for verification of the Chemical Weapons Convention. DAESAs were prepared by condensation of 2-bromoethane sulfonic acid with dialkylamines, and by condensation of dialkylaminoethyl chloride with sodium bisulfite. GC/EI-MS analysis of methyl esters of DAESAs yielded mass spectra; based on these spectra, generalized fragmentation routes are proposed that rationalize most of the characteristic ions.

  14. Differentiation of the Four Major Species of Cinnamons (C. burmannii, C. verum, C