Science.gov

Sample records for acceleration time-of-flight mass

  1. Time of flight mass spectrometer

    DOEpatents

    Ulbricht, Jr., William H.

    1984-01-01

    A time-of-flight mass spectrometer is described in which ions are desorbed from a sample by nuclear fission fragments, such that desorption occurs at the surface of the sample impinged upon by the fission fragments. This configuration allows for the sample to be of any thickness, and eliminates the need for complicated sample preparation.

  2. Resolution limitations from detector pulse width and jitter in a linear orthogonal-acceleration time-of-flight mass spectrometer.

    PubMed

    Coles, J N; Guilhaus, M

    1994-08-01

    Recent and ongoing advances in timing electronics together with the development of ionization techniques suited to time-of-flight mass spectrometry (TOF-MS) have contributed to renewed interest in this method of mass analysis. Whereas low resolving powers (m/†m < 500) were once an almost unavoidable drawback in TOF-MS, recent developments in instrument geometries have produced much higher resolving powers for many ion sources. The temporal width of detector pulses and jitter in timing electronics, however, lead to contributions to peak widths that are essentially independent of the mass-analyzer ion optics. The effective detector pulse width (†t d ≈ 1-10 ns typically) can be a limiting factor in the development of high resolution time-of-flight (TOF) instruments with modest drift lengths (∼1 m), It also reduces the mass resolution more seriously for light ions. This article presents a method for distinguishing the instrumental "ion arrival-time" resolution (R o) of a linear TOF mass analyzer from that which is locally measured at a particular mass, limited by the broadening of the detector pulse width and electronics. The method also provides an estimate of †t d, that is useful in determining the temporal performance of the detection system. The model developed here is tested with data from a recently constructed orthogonal-acceleration TOF mass spectrometer equipped with a commercially available transient recorder (a LeCroy 400-Msamplejs digital oscilloscope) from which we obtained R o = 4240 ± 100 [full width at half maximum (FWHM)) and †t d = 3.0 ± 0.1 ns (FWHM).

  3. IDENTIFYING COMPOUNDS USING SOURCE CID ON AN ORTHOGONAL ACCELERATION TIME-OF-FLIGHT MASS SPECTROMETER

    EPA Science Inventory

    Exact mass libraries of ESI and APCI mass spectra are not commercially available In-house libraries are dependent on CID parameters and are instrument specific. The ability to identify compounds without reliance on mass spectral libraries is therefore more crucial for liquid sam...

  4. Performance optimisation of a new-generation orthogonal-acceleration quadrupole-time-of-flight mass spectrometer.

    PubMed

    Bristow, Tony; Constantine, Jill; Harrison, Mark; Cavoit, Fabien

    2008-04-01

    Orthogonal-acceleration quadrupole time-of-flight (oa-QTOF) mass spectrometers, employed for accurate mass measurement, have been commercially available for well over a decade. A limitation of the early instruments of this type was the narrow ion abundance range over which accurate mass measurements could be made with a high degree of certainty. Recently, a new generation of oa-QTOF mass spectrometers has been developed and these allow accurate mass measurements to be recorded over a much greater range of ion abundances. This development has resulted from new ion detection technology and improved electronic stability or by accurate control of the number of ions reaching the detector. In this report we describe the results from experiments performed to evaluate the mass measurement performance of the Bruker micrOTOF-Q, a member of the new-generation oa-QTOFs. The relationship between mass accuracy and ion abundance has been extensively evaluated and mass measurement accuracy remained stable (+/-1.5 m m/z units) over approximately 3-4 orders of magnitude of ion abundance. The second feature of the Bruker micrOTOF-Q that was evaluated was the SigmaFit function of the software. This isotope pattern-matching algorithm provides an exact numerical comparison of the theoretical and measured isotope patterns as an additional identification tool to accurate mass measurement. The smaller the value, the closer the match between theoretical and measured isotope patterns. This information is then employed to reduce the number of potential elemental formulae produced from the mass measurements. A relationship between the SigmaFit value and ion abundance has been established. The results from the study for both mass accuracy and SigmaFit were employed to define the performance criteria for the micrOTOF-Q. This provided increased confidence in the selection of elemental formulae resulting from accurate mass measurements.

  5. Potential of gas chromatography-orthogonal acceleration time-of-flight mass spectrometry (GC-oaTOFMS) in flavor research.

    PubMed

    Fay, Laurent B; Newton, Anthony; Simian, Hervé; Robert, Fabien; Douce, David; Hancock, Peter; Green, Martin; Blank, Imre

    2003-04-23

    Gas chromatography-orthogonal acceleration time-of-flight mass spectrometry (GC-oaTOFMS) is an emerging technique offering a straightforward access to a resolving power up to 7000. This paper deals with the use of GC-oaTOFMS to identify the flavor components of a complex seafood flavor extract and to quantify furanones formed in model Maillard reactions. A seafood extract was selected as a representative example for complex food flavors and was previously analyzed using GC-quadrupole MS, leaving several molecules unidentified. GC-oaTOFMS analysis was focused on these unknowns to evaluate its potential in flavor research, particularly for determining exact masses. N-Methyldithiodimethylamine, 6-methyl-5-hepten-2-one, and tetrahydro-2,4-dimethyl-4H-pyrrolo[2,1-d]-1,3,5-dithiazine were successfully identified on the basis of the precise mass determination of their molecular ions and their major fragments. A second set of experiments was performed to test the capabilities of the GC-oaTOFMS for quantification. Calibration curves were found to be linear over a dynamic range of 10(3) for the quantification of furanones. The quantitative data obtained using GC-oaTOFMS confirmed earlier results that the formation of 4-hydroxy-2,5-dimethyl-3(2H)-furanone was favored in the xylose/glycine model reaction and 2(or 5)-ethyl-4-hydroxy-5(or 2)-methyl-3(2H)-furanone in the xylose/alanine model reaction. It was concluded that GC-oaTOFMS may become a powerful analytical tool for the flavor chemist for both identification and quantification purposes, the latter in particular when combined with stable isotope dilution assay.

  6. Detection of large ions in time-of-flight mass spectrometry: effects of ion mass and acceleration voltage on microchannel plate detector response.

    PubMed

    Liu, Ranran; Li, Qiyao; Smith, Lloyd M

    2014-08-01

    In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield γ (average number of electrons produced per ion collision) is found to be proportional to mv(3.1) (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

  7. How Constant Momentum Acceleration Decouples Energy and Space Focusing in Distance-of-Flight and Time-of-Flight Mass Spectrometries

    SciTech Connect

    Dennis, Elise; Gundlach-Graham, Alexander W.; Enke, Chris; Ray, Steven J.; Carado, Anthony J.; Barinaga, Charles J.; Koppenaal, David W.; Hieftje, Gary M.

    2013-05-01

    Time-of-flight (TOF) and distance-of-flight (DOF) mass spectrometers require means for focusing ions at the detector(s) because of initial dispersions of position and energy at the time of their acceleration. Time-of-flight mass spectrometers ordinarily employ constant energy acceleration (CEA), which creates a space-focus plane at which the initial spatial dispersion is corrected. In contrast, constant-momentum acceleration (CMA), in conjunction with an ion mirror, provides focus of the initial energy dispersion at the energy focus time for ions of all m/z at their respective positions along the flight path. With CEA, the initial energy dispersion is not simultaneously correctable as its effect on ion velocity is convoluted with that of the spatial dispersion. The initial spatial dispersion with CMA remains unchanged throughout the field-free region of the flight path, so spatial dispersion can be reduced before acceleration. Improved focus is possible when each dispersion can be addressed independently. With minor modification, a TOF mass spectrometer can be operated in CMA mode by treating the TOF detector as though it were a single element in the array of detectors that would be used in a DOF mass spectrometer. Significant improvement in mass resolution is thereby achieved, albeit over a narrow range of m/z values. In this paper, experimental and theoretical results are presented that illustrate the energy-focusing capabilities of both DOF and TOF mass spectrometry.

  8. Compact time-of-flight mass spectrometer

    SciTech Connect

    Belov, A.S.; Kubalov, S.A.; Kuzik, V.F.; Yakushev, V.P.

    1986-02-01

    This paper describes a time-of-flight mass spectrometer developed for measuring the parameters of a pulsed hydrogen beam. The duration of an electron-beam current pulse in the ionizer of the mass spectrometer can be varied within 2-20 usec, the pulse electron current is 0.6 mA, and the electron energy is 250 eV. The time resolution of the mass spectrometer is determined by the repetition period of the electron-beam current pulses and is 40 usec. The mass spectrometer has 100% transmission in the direction of motion of molecular-beam particles. The dimension of the mass spectrometer is 7 cm in this direction. The mass resolution is sufficient for determination of the composition of the hydrogen beam.

  9. Miniature Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Potember, Richard S.

    1999-01-01

    Major advances must occur to protect astronauts from prolonged periods in near-zero gravity and high radiation associated with extended space travel. The dangers of living in space must be thoroughly understood and methods developed to reverse those effects that cannot be avoided. Six of the seven research teams established by the National Space Biomedical Research Institute (NSBRI) are studying biomedical factors for prolonged space travel to deliver effective countermeasures. To develop effective countermeasures, each of these teams require identification of and quantitation of complex pharmacological, hormonal, and growth factor compounds (biomarkers) in humans and in experimental animals to develop an in-depth knowledge of the physiological changes associated with space travel. At present, identification of each biomarker requires a separate protocol. Many of these procedures are complicated and the identification of each biomarker requires a separate protocol and associated laboratory equipment. To carry all of this equipment and chemicals on a spacecraft would require a complex clinical laboratory; and it would occupy much of the astronauts time. What is needed is a small, efficient, broadband medical diagnostic instrument to rapidly identify important biomarkers for human space exploration. The Miniature Time-Of- Flight Mass Spectrometer Project in the Technology Development Team is developing a small, high resolution, time-of-flight mass spectrometer (TOFMS) to quantitatively measure biomarkers for human space exploration. Virtues of the JHU/APL TOFMS technologies reside in the promise for a small (less than one cubic ft), lightweight (less than 5 kg), low-power (less than 50 watts), rugged device that can be used continuously with advanced signal processing diagnostics. To date, the JHU/APL program has demonstrated mass capability from under 100 to beyond 10,000 atomic mass units (amu) in a very small, low power prototype for biological analysis. Further

  10. Metabolic profiling of yeast culture using gas chromatography coupled with orthogonal acceleration accurate mass time-of-flight mass spectrometry: application to biomarker discovery.

    PubMed

    Kondo, Elsuida; Marriott, Philip J; Parker, Rhiannon M; Kouremenos, Konstantinos A; Morrison, Paul; Adams, Mike

    2014-01-01

    Yeast and yeast cultures are frequently used as additives in diets of dairy cows. Beneficial effects from the inclusion of yeast culture in diets for dairy mammals have been reported, and the aim of this study was to develop a comprehensive analytical method for the accurate mass identification of the 'global' metabolites in order to differentiate a variety of yeasts at varying growth stages (Diamond V XP, Yea-Sacc and Levucell). Microwave-assisted derivatization for metabolic profiling is demonstrated through the analysis of differing yeast samples developed for cattle feed, which include a wide range of metabolites of interest covering a large range of compound classes. Accurate identification of the components was undertaken using GC-oa-ToFMS (gas chromatography-orthogonal acceleration-time-of-flight mass spectrometry), followed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) for data reduction and biomarker discovery. Semi-quantification (fold changes in relative peak areas) was reported for metabolites identified as possible discriminative biomarkers (p-value <0.05, fold change >2), including D-ribose (four fold decrease), myo-inositol (five fold increase), L-phenylalanine (three fold increase), glucopyranoside (two fold increase), fructose (three fold increase) and threitol (three fold increase) respectively. PMID:24356230

  11. On the high-resolution mass analysis of the product ions in tandem time-of-flight (TOF/TOF) mass spectrometers using a time-dependent re-acceleration technique.

    PubMed

    Kurnosenko, Sergey; Moskovets, Eugene

    2010-01-01

    The time-dependent reacceleration of product ions produced as a result of dissociation of a single precursor ion in a tandem time-of-flight mass spectrometer is considered for the first time. Analytical expressions for the shapes of electric pulses bringing all the kinetic energies of the product ions to the same value are derived for two cases: forward acceleration mode and deceleration, followed by re-acceleration in the reversed direction (reversed mode). Secondary time-of-flight focusing resulting from the re-acceleration in the reversed mode is shown to be mass-dependent and, when averaged over a wide mass range, the focusing is tight enough to provide mass resolution exceeding 10,000. After time-dependent re-acceleration, additional compression of the ion packet width leading to better mass resolution can be obtained by decelerating the ions in a constant field.

  12. How constant momentum acceleration decouples energy and space focusing in distance-of-flight and time-of-flight mass spectrometries.

    PubMed

    Dennis, Elise A; Gundlach-Graham, Alexander W; Enke, Christie G; Ray, Steven J; Carado, Anthony J; Barinaga, Charles J; Koppenaal, David W; Hieftje, Gary M

    2013-05-01

    Resolution in time-of-flight mass spectrometry (TOFMS) is ordinarily limited by the initial energy and space distributions within an instrument's acceleration region and by the length of the field-free flight zone. With gaseous ion sources, these distributions lead to systematic flight-time errors that cannot be simultaneously corrected with conventional static-field ion-focusing devices (i.e., an ion mirror). It is known that initial energy and space distributions produce non-linearly correlated errors in both ion velocity and exit time from the acceleration region. Here we reinvestigate an old acceleration technique, constant-momentum acceleration (CMA), to decouple the effects of initial energy and space distributions. In CMA, only initial ion energies (and not their positions) affect the velocity ions gain. Therefore, with CMA, the spatial distribution within the acceleration region can be manipulated without creating ion-velocity error. The velocity differences caused by a spread in initial ion energy can be corrected with an ion mirror. We discuss here the use of CMA and independent focusing of energy and space distributions for both distance-of-flight mass spectrometry (DOFMS) and TOFMS. Performance characteristics of our CMA-DOFMS and CMA-TOFMS instrument, fitted with a glow-discharge ionization source, are described. In CMA-DOFMS, resolving powers (FWHM) of greater than 1000 are achieved for atomic ions with a flight length of 285 mm. In CMA-TOFMS, only ions over a narrow range of m/z values can be energy-focused; however, the technique offers improved resolution for these focused ions, with resolving powers of greater than 2000 for a separation distance of 350 mm.

  13. Screening and identification of unknown contaminants in water with liquid chromatography and quadrupole-orthogonal acceleration-time-of-flight tandem mass spectrometry.

    PubMed

    Bobeldijk, I; Vissers, J P; Kearney, G; Major, H; Van Leerdam, J A

    2001-09-21

    In order to assess and maintain the quality of surface waters, target compound monitoring is often not sufficient. Many unknown micro-contaminants are present in water, originating in municipal, industrial or agricultural effluents. Some of these might pose a risk to drinking water production and consequently to human health. The possibilities of screening surface water and identification of these non-target water pollutants with modern data acquisition possibilities of hybrid quadrupole-orthogonal acceleration time of flight mass spectrometers (Q-TOF), such as data-dependent MS to MS/MS switching were investigated. Using model compounds, a procedure for the liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening of water extracts was developed, enabling the detection and identification of compounds at levels < or = 0.25 microg/l in surface water. Based on the accurate mass the elemental compositions for the precursor and product ions are calculated. The calculated chemical formulae are searched against the Merck index, the NIST library, an own database containing about 2,500 water pollutants (pesticides and other contaminants) as well as a CI-CID library containing tandem MS spectra of about 100 water contaminants. The developed approach was applied for the identification of unknown compounds, present in native surface water extract. For three of these compounds, structures were proposed. Confirmation of the proposed structures with standards was beyond the scope of this study.

  14. Inductively Coupled Plasma Zoom-Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Dennis, Elise A.; Ray, Steven J.; Enke, Christie G.; Hieftje, Gary M.

    2016-03-01

    A zoom-time-of-flight mass spectrometer has been coupled to an inductively coupled plasma (ICP) ionization source. Zoom-time-of-flight mass spectrometry (zoom-TOFMS) combines two complementary types of velocity-based mass separation. Specifically, zoom-TOFMS alternates between conventional, constant-energy acceleration (CEA) TOFMS and energy-focused, constant-momentum acceleration (CMA) (zoom) TOFMS. The CMA mode provides a mass-resolution enhancement of 1.5-1.7× over CEA-TOFMS in the current, 35-cm ICP-zoom-TOFMS instrument geometry. The maximum resolving power (full-width at half-maximum) for the ICP-zoom-TOFMS instrument is 1200 for CEA-TOFMS and 1900 for CMA-TOFMS. The CMA mode yields detection limits of between 0.02 and 0.8 ppt, depending upon the repetition rate and integration time—compared with single ppt detection limits for CEA-TOFMS. Isotope-ratio precision is shot-noise limited at approximately 0.2% relative-standard deviation (RSD) for both CEA- and CMA-TOFMS at a 10 kHz repetition rate and an integration time of 3-5 min. When the repetition rate is increased to 43.5 kHz for CMA, the shot-noise limited, zoom-mode isotope-ratio precision is improved to 0.09% RSD for the same integration time.

  15. Rocket-borne time-of-flight mass spectrometry

    NASA Technical Reports Server (NTRS)

    Reiter, R. F.

    1976-01-01

    Theoretical and numerical analyses are made of planar, cylindrical and spherical-electrode two-field time-of-flight mass spectrometers in order to optimize their operating conditions. A method is introduced which can improve the resolving power of these instruments by a factor of 7.5. Potential barrier gating in time-of-flight mass spectrometers is also analyzed. Experimental studies of a miniature cylindrical-electrode and a hemispherical-electrode time-of-flight mass spectrometer are presented. Their sensitivity and ability to operate at D-region pressures with an open source make them ideal instruments for D-region ion composition measurements. A sounding rocket experiment package carrying a cylindrical electrode time-of-flight mass spectrometer was launched. The data indicate that essentially 100% of the positive electric charge on positive ions is carried by ions with mass-to-charge ratios greater than 500 below an altitude of 92 km. These heavy charge carriers were present at altitudes up to about 100 km.

  16. A Segmented Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.; Iga, I.; Rao, M. V. V. S.

    1995-01-01

    The present paper describes the design of a time-of-flight mass spectrometer (TOFMS) in which the single flight tube of a conventional TOFMS has been replaced by several cylindrical electrostatic lenses in tandem. By a judicious choice of voltages on these lenses, an improved TOFMS has been realized which has a superior mass and energy resolution, shorter flight lengths, excellent signal-to-noise ratio and less stringent requirements on the bias voltages.

  17. Miniature Focusing Time-of-Flight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Kanik, Isik; Srivastava, Santosh

    2005-01-01

    An improved miniature time-of-flight mass spectrometer has been developed in a continuing effort to minimize the sizes, weights, power demands, and costs of mass spectrometers for such diverse applications as measurement of concentrations of pollutants in the atmosphere, detecting poisonous gases in mines, and analyzing exhaust gases of automobiles. Advantageous characteristics of this mass spectrometer include the following: It is simple and rugged. Relative to prior mass spectrometers, it is inexpensive to build. There is no need for precise alignment of its components. Its mass range is practically unlimited Relative to prior mass spectrometers, it offers high sensitivity (ability to measure relative concentrations as small as parts per billion). Its resolution is one dalton (one atomic mass unit). An entire mass spectrum is recorded in a single pulse. (In a conventional mass spectrometer, a spectrum is recorded mass by mass.) The data-acquisition process takes only seconds. It is a lightweight, low-power, portable instrument. Although time-of-flight mass spectrometers (TOF-MSs) have been miniaturized previously, their performances have not been completely satisfactory. An inherent adverse effect of miniaturization of a TOF-MS is a loss of resolution caused by reduction of the length of its flight tube. In the present improved TOF-MS, the adverse effect of shortening the flight tube is counteracted by (1) using charged-particle optics to constrain ion trajectories to the flight-tube axis while (2) reducing ion velocities to increase ion flight times. In the present improved TOF-MS, a stream of gas is generated by use of a hypodermic needle. The stream of gas is crossed by an energy-selected, pulsed beam of electrons (see Figure 1). The ions generated by impingement of the electrons on the gas atoms are then focused by three cylindrical electrostatic lenses, which constitute a segmented flight tube. After traveling along the flight tube, the ions enter a charged

  18. Continuous time-of-flight ion mass spectrometer

    DOEpatents

    Funsten, Herbert O.; Feldman, William C.

    2004-10-19

    A continuous time-of-flight mass spectrometer having an evacuated enclosure with means for generating an electric field located in the evacuated enclosure and means for injecting a sample material into the electric field. A source of continuous ionizing radiation injects ionizing radiation into the electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between arrival of a secondary electron out of said ionized atoms or molecules at a first predetermined location and arrival of a sample ion out of said ionized atoms or molecules at a second predetermined location.

  19. Avalanche photodiode based time-of-flight mass spectrometry

    SciTech Connect

    Ogasawara, Keiichi Livi, Stefano A.; Desai, Mihir I.; Ebert, Robert W.; McComas, David J.; Walther, Brandon C.

    2015-08-15

    This study reports on the performance of Avalanche Photodiodes (APDs) as a timing detector for ion Time-of-Flight (TOF) mass spectroscopy. We found that the fast signal carrier speed in a reach-through type APD enables an extremely short timescale response with a mass or energy independent <2 ns rise time for <200 keV ions (1−40 AMU) under proper bias voltage operations. When combined with a microchannel plate to detect start electron signals from an ultra-thin carbon foil, the APD comprises a novel TOF system that successfully operates with a <0.8 ns intrinsic timing resolution even using commercial off-the-shelf constant-fraction discriminators. By replacing conventional total-energy detectors in the TOF-Energy system, APDs offer significant power and mass savings or an anti-coincidence background rejection capability in future space instrumentation.

  20. Linear electronic field time-of-flight ion mass spectrometers

    DOEpatents

    Funsten, Herbert O.

    2010-08-24

    Time-of-flight mass spectrometer comprising a first drift region and a second drift region enclosed within an evacuation chamber; a means of introducing an analyte of interest into the first drift region; a pulsed ionization source which produces molecular ions from said analyte of interest; a first foil positioned between the first drift region and the second drift region, which dissociates said molecular ions into constituent atomic ions and emits secondary electrons; an electrode which produces secondary electrons upon contact with a constituent atomic ion in second drift region; a stop detector comprising a first ion detection region and a second ion detection region; and a timing means connected to the pulsed ionization source, to the first ion detection region, and to the second ion detection region.

  1. Laser Time-of-Flight Mass Spectrometry for Space

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, W. B.; Managadze, G. G.; McEntire, R. W.; Cheng, A. F.; Green, W. J.

    2000-01-01

    A miniature reflection time-of-flight mass spectrometer for in situ planetary surface analysis is described. The laser ablation mass spectrometer (LAMS) measures the regolith's elemental and isotopic composition without high-voltage source extraction or sample preparation. The compact size (< 2 x 10(exp 3) cubic cm) and low mass (approximately 2 kg) of LAMS, due to its fully coaxial design and two-stage reflectron, fall within the strict resource limitations of landed science missions to solar system bodies. A short-pulse laser focused to a spot with a diameter approximately 30-50 micrometers is used to obtain microscopic surface samples. Assisted by a microimager, LAMS can interactively select and analyze a range of compositional regions (with lateral motion) and with repeated pulses can access unweathered, subsurface materials. The mass resolution is calibrated to distinguish isotopic peaks at unit masses, and detection limits are on resolved to a few ppm. The design and calibration method of a prototype LAMS device is described, which include the development of preliminary relative sensitivity coefficients for major element bulk abundance measurements.

  2. AUTOMATED ELEMENTAL COMPOSITION DETERMINATION AND CORRELATION OF PRECURSOR WITH PRODUCT IONS BASED ON ORTHOGONAL ACCELERATION, TIME-OF-FLIGHT MASS SPECTRA

    EPA Science Inventory

    For more than a decade in our laboratory, elemental compositions of ions in mass spectra havebeen routinely determined by measuring exact masses and relative isotopic abundances of ions in isotopicclusters using a GC coupled to a double focusing mass spectrometer.1 HPLC interfac...

  3. LVGEMS Time-of-Flight Mass Spectrometry on Satellites

    NASA Technical Reports Server (NTRS)

    Herrero, Federico

    2013-01-01

    NASA fs investigations of the upper atmosphere and ionosphere require measurements of composition of the neutral air and ions. NASA is able to undertake these observations, but the instruments currently in use have their limitations. NASA has extended the scope of its research in the atmosphere and now requires more measurements covering more of the atmosphere. Out of this need, NASA developed multipoint measurements using miniaturized satellites, also called nanosatellites (e.g., CubeSats), that require a new generation of spectrometers that can fit into a 4 4 in. (.10 10 cm) cross-section in the upgraded satellites. Overall, the new mass spectrometer required for the new depth of atmospheric research must fulfill a new level of low-voltage/low-power requirements, smaller size, and less risk of magnetic contamination. The Low-Voltage Gated Electrostatic Mass Spectrometer (LVGEMS) was developed to fulfill these requirements. The LVGEMS offers a new spectrometer that eliminates magnetic field issues associated with magnetic sector mass spectrometers, reduces power, and is about 1/10 the size of previous instruments. LVGEMS employs the time of flight (TOF) technique in the GEMS mass spectrometer previously developed. However, like any TOF mass spectrometer, GEMS requires a rectangular waveform of large voltage amplitude, exceeding 100 V -- that means that the voltage applied to one of the GEMS electrodes has to change from 0 to 100 V in a time of only a few nanoseconds. Such electronic speed requires more power than can be provided in a CubeSat. In the LVGEMS, the amplitude of the rectangular waveform is reduced to about 1 V, compatible with digital electronics supplies and requiring little power.

  4. Expansion of a shock plasma in the accelerating field of a parallel-plate capacitor in a time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Semkin, N. D.; Pomel'nikov, R. A.; Telegin, A. M.

    2014-05-01

    We have solved the problem of expansion of a multicomponent shock plasma (initiated by an impact of a fast microprojectile against a solid target) to vacuum in the electric field of a parallel-plate capacitor. The results of calculations can be used in the development of a dust impact mass spectrometer for studying the elemental composition of micrometeorites.

  5. Dynamically Multiplexed Ion Mobility Time-of-Flight Mass Spectrometry

    SciTech Connect

    Belov, Mikhail E.; Clowers, Brian H.; Prior, David C.; Danielson, William F.; Liyu, Andrei V.; Petritis, Brianne O.; Smith, Richard D.

    2008-08-01

    Ion Mobility Spectrometry–Time-of-Flight Mass Spectrometry (IMS-TOFMS) has been increasingly used in analysis of complex biological samples. A major challenge is to transform IMS-TOFMS to a high-sensitivity high-throughput platform for e.g. proteomics applications. In this work, we have developed and integrated three advanced technologies, enabling (1) efficient ion accumulation in the ion funnel trap prior to IMS separation, (2) multiplexing (MP) of ion packet introduction into the IMS drift tube and (3) signal detection with an analog-to-digital converter (ADC), into the IMS-TOFMS system for the high-throughput analysis of highly complex proteolytic digests of e.g. blood plasma. To better address variable sample complexity, we have additionally developed and rigorously evaluated a new dynamic MP approach that ensures correlation of the analyzer performance with an ion source function, and provides the improved dynamic range and sensitivity. The MP IMS-TOF MS instrument has been shown to reliably detect peptides at a concentration of 1 nM in a highly complex matrix, as well as to provide a four orders of magnitude dynamic range and a mass measurement accuracy of better than 5 ppm. When matched against human blood plasma database, the detected IMS-TOF features yielded ~ 700 unique peptide identifications at a false discovery rate (FDR) of ~ 7.5 %. Accounting for IMS information gave rise to a projected FDR of ~ 4 %. Signal reproducibility was found to be greater than 80 %, while the variations in the number of unique peptide identifications were < 15 %. A single sample analysis was completed in 15 min, corresponding to approximately an order of magnitude improvement compared to a more conventional LC-MS approach.

  6. Analysis of ion dynamics and peak shapes for delayed extraction time-of-flight mass spectrometers

    NASA Astrophysics Data System (ADS)

    Collado, V. M.; Ponciano, C. R.; Fernandez-Lima, F. A.; da Silveira, E. F.

    2004-06-01

    The dependence of time-of-flight (TOF) peak shapes on time-dependent extraction electric fields is studied theoretically. Conditions for time focusing are analyzed both analytically and numerically for double-acceleration-region TOF spectrometers. Expressions for the spectrometer mass resolution and for the critical delay time are deduced. Effects due to a leakage field in the first acceleration region are shown to be relevant under certain conditions. TOF peak shape simulations for the delayed extraction method are performed for emitted ions presenting a Maxwellian initial energy distribution. Calculations are compared to experimental results of Cs+ emission due to CsI laser ablation.

  7. Metabolomics reveals positive acceleration(+Gz)-induced metabolic perturbations and the protective effect of Ginkgo biloba extract in a rat model based on ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    PubMed

    Yang, Zhihui; Zhao, Andong; Li, Zhongdong; Ge, Hua; Li, Tonghua; Zhang, Fucheng; Zhan, Hao; Wang, Jianchang

    2016-06-01

    Positive acceleration (+Gz) in the head-to-foot direction generated by modern high-performance fighter jets during flight maneuvers is characterized by high G values and a rapid rate of acceleration, and is often long in duration and a repeated occurrence. The acceleration overload far exceeds the pilot's physiological tolerance limits and causes considerable strain on several organ systems. Despite the importance of monitoring pathophysiological alterations related to +Gz exposure, we lack a complete explanation of the pathophysiology of +Gz exposure. Ginkgo biloba extract (GBE) is a classic traditional Chinese medicine (TCM) that might exert a protective effect against +Gz exposure. However, its mechanism remains unclear. Here, a metabolomics approach based on ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOFMS) was used to characterize +Gz-induced metabolic fluctuations in a rat model and to evaluate the protective effect of GBE. Using partial least-squares discriminant analysis for the classification and selection of biomarkers, eighteen serum metabolites related to +Gz exposure were identified, and were found to primarily involve the fatty acid β-oxidation pathway, glycerophospholipid metabolism, phospholipid metabolism, bile acid metabolism, purine metabolism and lysine metabolism. Taking these potential biomarkers as screening indexes, we found that GBE could reverse the pathological process of +Gz exposure by partially regulating the perturbed fatty acid β-oxidation pathway, glycerophospholipid metabolism, purine metabolism and lysine metabolism. This indicates that UHPLC-Q-TOFMS-based metabolomics provides a powerful tool to reveal serum metabolic fluctuations in response to +Gz exposure and to study the mechanism underlying TCM. PMID:27010354

  8. Impact energy measurement in time-of-flight mass spectrometry with cryogenic microcalorimeters.

    PubMed

    Hilton, G C; Martinis, J M; Wollman, D A; Irwin, K D; Dulcie, L L; Gerber, D; Gillevet, P M; Twerenbold, D

    1998-02-12

    Time-of-flight mass spectrometry-most notably matrix-assisted laser-desorption-ionization time-of-flight (MALDI-TOF) spectrometry-is an important class of techniques for the study of proteins and other biomolecules. Although these techniques provide excellent performance for masses up to about 20,000 daltons, there has been limited success in achieving good mass resolution at higher masses. This is because the sensitivity of the microchannel plate (MCP) detectors used in most systems decreases rapidly with increasing particle mass, limiting the utility of MCP detectors for very large masses. It has recently been proposed that cryogenic particle detectors may provide a solution to these difficulties. Cryogenic detectors measure the thermal energy deposited by the particle impact, and thus have a sensitivity that is largely independent of particle mass. Recent experiments have demonstrated the sensitivity of cryogenic particle detectors to single biomolecules, a quantum efficiency several orders of magnitude larger than the MCP detectors, and sensitivity to masses as large as 750,000 daltons. Here we present results demonstrating an order of magnitude better energy resolution than previous measurements, allowing direct determination of particle charge state during acceleration. Although application of these detectors to practical mass spectrometry will require further development of the detectors and cryogenics, these detectors can be used to elucidate the performance-limiting processes that occur in such systems.

  9. Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis.

    PubMed

    Shastri, Lokesh A; Kailasa, Suresh Kumar; Wu, Hui-Fen

    2009-08-01

    Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5-12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics.

  10. Quasi-dynamic mode of nanomembranes for time-of-flight mass spectrometry of proteins.

    PubMed

    Park, Jonghoo; Kim, Hyunseok; Blick, Robert H

    2012-04-21

    Mechanical resonators realized on the nano-scale by now offer applications in mass-sensing of biomolecules with extraordinary sensitivity. The general idea is that perfect mechanical biosensors should be of extremely small size to achieve zeptogram sensitivity in weighing single molecules similar to a balance. However, the small scale and long response time of weighing biomolecules with a cantilever restrict their usefulness as a high-throughput method. Commercial mass spectrometry (MS) such as electro-spray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-MS are the gold standards to which nanomechanical resonators have to live up to. These two methods rely on the ionization and acceleration of biomolecules and the following ion detection after a mass selection step, such as time-of-flight (TOF). Hence, the spectrum is typically represented in m/z, i.e. the mass to ionization charge ratio. Here, we describe the feasibility and mass range of detection of a new mechanical approach for ion detection in time-of-flight mass spectrometry, the principle of which is that the impinging ion packets excite mechanical oscillations in a silicon nitride nanomembrane. These mechanical oscillations are henceforth detected via field emission of electrons from the nanomembrane. Ion detection is demonstrated in MALDI-TOF analysis over a broad range with angiotensin, bovine serum albumin (BSA), and an equimolar protein mixture of insulin, BSA, and immunoglobulin G (IgG). We find an unprecedented mass range of operation of the nanomembrane detector. PMID:22378023

  11. Ion Funnel Trap Interface for Orthogonal Time-of-Flight Mass Spectrometry

    SciTech Connect

    Ibrahim, Yehia M.; Belov, Mikhail E.; Tolmachev, Aleksey V.; Prior, David C.; Smith, Richard D.

    2007-10-15

    A combined electrodynamic ion funnel and ion trap coupled to an orthogonal acceleration (oa)-time-of-flight mass spectrometer was developed and characterized. The ion trap was incorporated through the use of added terminal electrodynamic ion funnel electrodes enabling control over the axial dc gradient in the trap section. The ion trap operates efficiently at a pressure of ~1 Torr, and measurements indicate a maximum charge capacity of ~3 × 107 charges. An order of magnitude increase in sensitivity was observed in the analysis of low concentration peptides mixtures with orthogonal acceleration (oa)-time-of-flight mass spectrometry (oa-TOF MS) in the trapping mode as compared to the continuous regime. A signal increase in the trapping mode was accompanied by reduction in the chemical background, due to more efficient desolvation of, for example, solvent related clusters. Controlling the ion trap ejection time was found to result in efficient removal of singly charged species and improving signal-to-noise ratio (S/N) for the multiply charged analytes.

  12. Sensitivity Upgrades to the Idaho Accelerator Center Neutron Time of Flight Spectrometer

    SciTech Connect

    Thompson, S. J.; Kinlaw, M. T.; Harmon, J. F.; Wells, D. P.; Hunt, A. W.

    2007-10-26

    Past experiments have shown that discrimination between between fissionable and non-fissionable materials is possible using an interrogation technique that monitors for high energy prompt fission neutrons. Several recent upgrades have been made to the neutron time of flight spectrometer at the Idaho Accelerator Center with the intent of increasing neutron detection sensitivity, allowing for system use in nonproliferation and security applications.

  13. Development of grazing incidence devices for space-borne time of flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Cadu, A.; Devoto, P.; Louarn, P.; Sauvaud, J.-A.

    2012-04-01

    Time of flight mass spectrometer is widely used to study space plasmas in planetary and solar missions. This space-borne instrument selects ions in function of their energy through an electrostatic analyzer. Particles are then post-accelerated to energies in the range of 20 keV to cross a carbon foil. At the foil exit, electrons are emitted and separated from ion beam in the time of flight section. A first detector (a Micro-Channel Plate or MCP) emits a start signal at electron arrival and a second one emits a stop signal at incident ion end of path. The time difference gives the speed of the particle and its mass can be calculated, knowing its initial energy. However, current instruments suffer from strong limitations. The post acceleration needs very high voltage power supplies which are heavy, have a high power consumption and imply technical constraints for the development. A typical instrument weighs from 5 to 6 kg, includes a 20 kV power supply, consumes a least 5 W and encounters corona effect and electrical breakdown problems. Moreover, despite the particle high energy range, scattering and straggling phenomena in the carbon foil significantly reduce the instrument overall resolution. Some methods, such as electrostatic focus lenses or reflectrons, really improve mass separation but global system efficiency remains very low because of the charge state dependence of such devices. The main purpose of our work is to replace carbon foil by grazing incidence MCP's - also known as MPO's, for Micro Pore Optics - for electron emission. Thus, incident particles would back-scatter onto the channel inner surface with an angle of a few degrees. With this solution, we can decrease dispersion sources and lower the power supplies to post accelerate ions. The result would be a lighter and simpler instrument with a substantial resolution improvement. We have first simulated MPO's behavior with TRIM and MARLOWE Monte-Carlo codes. Energy scattering and output angle computed

  14. New high-resolution electrostatic ion mass analyzer using time of flight

    NASA Technical Reports Server (NTRS)

    Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Lundgren, R. A.; Sheldon, R. B.

    1990-01-01

    The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

  15. A Design for a Compact Time-of-Flight Mass Spectrometer

    SciTech Connect

    Manard, M.

    2012-10-01

    The design of a prototype, compact time-of-flight (TOF) mass spectrometer (MS) is described. The system primarily consists of an ion acceleration/focusing/steering assembly (AFSA), an 8 cm field-free region, a 4 cm, dual-stage reflectron and a miniature microchannel plate detector. Consequently, the resulting flight length of the system is 12 cm. The system has been designed with the capability to sample directly from atmosphere at ambient pressures. This is accomplished through the use of an electrodynamic ion funnel, housed in an intermediate-vacuum chamber that is coupled to the inlet of the TOF chamber. TOF spectra were obtained using noble gases (Ar, Kr and Xe) as test chemicals. These measured flight times were used to probe the performance of the instrument. A temporal resolution (tflight/Δt) of approximately 125, acquired using 129Xe+, has been measured for the system.

  16. Linear electric field time-of-flight ion mass spectrometer

    DOEpatents

    Funsten, Herbert O.; Feldman, William C.

    2008-06-10

    A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

  17. Reflectron Time-of-Flight Mass Spectrometer (REMAS) Instrumentation

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, W. B.; McEntire, R. W.; Cheng, A. F.

    2000-01-01

    The restricted mass and power budgets of landed science missions present a challenge to obtaining detailed analyses of planetary bodies. In situ studies, whether alone or as reconnaissance for sample return, must rely on highly miniaturized and autonomous instrumentation. Such devices must still produce useful data sets from a minimum of measurements. The great desire to understand the surfaces and interiors of planets, moons, and small bodies had driven the development of small, robotic techniques with ever-increasing capabilities. One of the most important goals on a surface mission is to study composition in many geological contexts. The mineralogical, molecular, elemental, and isotopic content of near-surface materials (regolith, rocks, soils, dust, etc.) at a variety of sites can complement broader imaging to describe the makeup and formative history of the body in question. Instruments that perform this site-to-site analysis must be highly transportable and work as a suite. For instance, a camera, microscope, spectrophotometer, and mass spectrometer can share several components and operate under a parallel command structure. Efficient use of multiple systems on a small rover has been demonstrated on the Mars Pathfinder mission.

  18. Time-of-flight mass spectrometry for explosives trace detection

    NASA Astrophysics Data System (ADS)

    Pettersson, Anna; Elfving, Anders; Elfsberg, Mattias; Hurtig, Tomas; Johansson, Niklas; Al-Khalili, Ahmed; Käck, Petra; Wallin, Sara; Östmark, Henric

    2012-06-01

    This paper presents the ongoing development of a laser ionization mass spectrometric system to be applied for screening for security related threat substances, specifically explosives. The system will be part of a larger security checkpoint system developed and demonstrated within the FP7 project EFFISEC to aid border police and customs at outer border checks. The laser ionization method of choice is SPI (single photon ionization), but the system also incorporates optional functionalities such as a cold trap and/or a particle concentrator to facilitate detection of minute amounts of explosives. The possibility of using jet-REMPI as a verification means is being scrutinized. Automated functionality and user friendliness is also considered in the demo system development.

  19. Optimisation of the design parameters of a reflection geometry time-of-flight mass spectrometer

    SciTech Connect

    Sankari, M.; Suryanarayana, M.V.

    1996-12-31

    Optimisation of the design parameters for a reflectron geometry time-of-flight mass spectrometer (RTOFMS) has been done by a simplex optimisation method based on a Nelder-Mead Algorithm. The space and energy resolutions obtained are 6100 and 7400, respectively, for mass 200 amu. The resolution is quite adequate for all the applications of RIMS. A high resolution reflectron geometry time-of-flight mass spectrometer (RTOFMS) for resonance ionisation mass spectrometer (RIMS) is being fabricated, based on these optimised design parameters. 19 refs., 9 figs., 2 tabs.

  20. Design Study for a Multi-Reflection Time-of-Flight Mass Spectrograph for Very Short Lived Nuclei

    NASA Astrophysics Data System (ADS)

    Yoon, Jin Woo; Park, Young-Ho; Im, Kang-Bin; Kim, Gi Dong; Kim, Yong Kyun

    The multi-reflection time-of-flight mass spectrometer (MR-TOF-MS) has been designed for the high precision mass measurement system in RAON accelerator facility, which will be constructed in Korea. Mirror-electrode potentials were numerically optimized by Nelder-Mead algorithm. The temporal spread and the mass-resolving power were calculated for the 132Sn+ ions with an energy spread of 20 eV and an emittance of 3 π mm mrad; the mass resolving power over 105 was achieved. MR-TOF-MS will be used for the isobar separation and the mass measurement for very short-lived isotopes.

  1. Visualization of acetaminophen-induced liver injury by time-of-flight secondary ion mass spectrometry.

    PubMed

    Murayama, Yohei; Satoh, Shuya; Hashiguchi, Akinori; Yamazaki, Ken; Hashimoto, Hiroyuki; Sakamoto, Michiie

    2015-11-01

    Time-of-flight secondary ion mass spectrometry (MS) provides secondary ion images that reflect distributions of substances with sub-micrometer spatial resolution. To evaluate the use of time-of-flight secondary ion MS to capture subcellular chemical changes in a tissue specimen, we visualized cellular damage showing a three-zone distribution in mouse liver tissue injured by acetaminophen overdose. First, we selected two types of ion peaks related to the hepatocyte nucleus and cytoplasm using control mouse liver. Acetaminophen-overdosed mouse liver was then classified into three areas using the time-of-flight secondary ion MS image of the two types of peaks, which roughly corresponded to established histopathological features. The ion peaks related to the cytoplasm decreased as the injury became more severe, and their origin was assumed to be mostly glycogen based on comparison with periodic acid-Schiff staining images and reference compound spectra. This indicated that the time-of-flight secondary ion MS image of the acetaminophen-overdosed mouse liver represented the chemical changes mainly corresponding to glycogen depletion on a subcellular scale. In addition, this technique also provided information on lipid species related to the injury. These results suggest that time-of-flight secondary ion MS has potential utility in histopathological applications.

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

    SciTech Connect

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

    1997-02-01

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

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

    ERIC Educational Resources Information Center

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

    2007-01-01

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

  4. A compact time-of-flight mass spectrometer for ion source characterization

    SciTech Connect

    Chen, L. Wan, X.; Jin, D. Z.; Tan, X. H.; Huang, Z. X.; Tan, G. B.

    2015-03-15

    A compact time-of-flight mass spectrometer with overall dimension of about 413 × 250 × 414 mm based on orthogonal injection and angle reflection has been developed for ion source characterization. Configuration and principle of the time-of-flight mass spectrometer are introduced in this paper. The mass resolution is optimized to be about 1690 (FWHM), and the ion energy detection range is tested to be between about 3 and 163 eV with the help of electron impact ion source. High mass resolution and compact configuration make this spectrometer useful to provide a valuable diagnostic for ion spectra fundamental research and study the mass to charge composition of plasma with wide range of parameters.

  5. DETERMINATION OF ION AND NEUTRAL LOSS COMPOSITIONS AND DECONVOLUTION OF PRODUCT ION MASS SPECTRA USING AN ORTHOGONAL ACCELERATION, TIME-OF-FLIGHT MASS SPECTROMETER AND AN ION CORRELATION PROGRAM

    EPA Science Inventory

    Exact masses of monoisotopic ions and the relative isotopic abundances (RIAs) of ions greater in mass by 1 and 2 Da than the monoisotopic ion are independent and complementary physical properties useful for istinguishing among ion compositions possible for a given nominal mass. U...

  6. 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.

  7. Evaluation of Inductively Couple Plasma-time-of-Flight Mass Spectrometry for Laser Ablation Analyses

    SciTech Connect

    S.J. Bajic; D.B. Aeschliman; D.P. Baldwin; R.S. Houk

    2003-09-30

    The purpose of this trip to LECO Corporation was to test the non-matrix matched calibration method and the principal component analysis (PCA) method on a laser ablation-inductively coupled plasma-time of flight mass spectrometry (LA-ICP-TOFMS) system. An LA-ICP-TOFMS system allows for multielement single-shot analysis as well as spatial analysis on small samples, because the TOFMS acquires an entire mass spectrum for all ions extracted simultaneously from the ICP. The TOFMS system differs from the double-focusing mass spectrometer, on which the above methods were developed, by having lower sensitivity and lower mass resolution.

  8. Invited article: Characterization of background sources in space-based time-of-flight mass spectrometers.

    PubMed

    Gilbert, J A; Gershman, D J; Gloeckler, G; Lundgren, R A; Zurbuchen, T H; Orlando, T M; McLain, J; von Steiger, R

    2014-09-01

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  9. Invited Article: Characterization of background sources in space-based time-of-flight mass spectrometers

    SciTech Connect

    Gilbert, J. A.; Gershman, D. J.; Gloeckler, G.; Lundgren, R. A.; Zurbuchen, T. H.; Orlando, T. M.; McLain, J.; Steiger, R. von

    2014-09-15

    For instruments that use time-of-flight techniques to measure space plasma, there are common sources of background signals that evidence themselves in the data. The background from these sources may increase the complexity of data analysis and reduce the signal-to-noise response of the instrument, thereby diminishing the science value or usefulness of the data. This paper reviews several sources of background commonly found in time-of-flight mass spectrometers and illustrates their effect in actual data using examples from ACE-SWICS and MESSENGER-FIPS. Sources include penetrating particles and radiation, UV photons, energy straggling and angular scattering, electron stimulated desorption of ions, ion-induced electron emission, accidental coincidence events, and noise signatures from instrument electronics. Data signatures of these sources are shown, as well as mitigation strategies and design considerations for future instruments.

  10. Note: A novel dual-channel time-of-flight mass spectrometer for photoelectron imaging spectroscopy

    SciTech Connect

    Qin Zhengbo; Wu Xia; Tang Zichao

    2013-06-15

    A novel dual-channel time-of-flight mass spectrometer (D-TOFMS) has been designed to select anions in the photoelectron imaging measurements. In this instrument, the radiation laser can be triggered precisely to overlap with the selected ion cloud at the first-order space focusing plane. Compared with that of the conventional single channel TOFMS, the in situ mass selection performance of D-TOFMS is significantly improved. Preliminary experiment results are presented for the mass-selected photodetachment spectrum of F{sup -} to demonstrate the capability of the instrument.

  11. Combined distance-of-flight and time-of-flight mass spectrometer

    DOEpatents

    Enke, Christie G; Ray, Steven J; Graham, Alexander W; Hieftje, Gary M; Barinaga, Charles J; Koppenaal, David W

    2014-02-11

    A combined distance-of-flight mass spectrometry (DOFMS) and time-of-flight mass spectrometry (TOFMS) instrument includes an ion source configured to produce ions having varying mass-to-charge ratios, a first detector configured to determine when each of the ions travels a predetermined distance, a second detector configured to determine how far each of the ions travels in a predetermined time, and a detector extraction region operable to direct portions of the ions either to the first detector or to the second detector.

  12. Aerosol matrix-assisted laser desorption ionization for liquid chromatography/time-of-flight mass spectrometry

    SciTech Connect

    Murray, K.K.; Lewis, T.M.; Beeson, M.D.; Russell, D.H. )

    1994-05-15

    We report the application of aerosol matrix-assisted laser desorption ionization (MALDI) to liquid chromatography/mass spectrometry (LC/MS). The aerosol MALDI experiment uses aerosol liquid introduction in conjunction with pulsed UV laser ionization to form ions from large biomolecules in solution. Mass analysis is achieved in a time-of-flight mass spectrometer. In the LC/MALDI-MS experiment, the matrix solution is combined with the column effluent in a mixing tee, LC/MALDI-MS is demonstrated for the separation of bradykinin, gramicidin S, and myoglobin. 32 refs., 8 figs., 1 tab.

  13. Time-of-flight mass spectrometry of DNA laser-ablated from frozen aqueous solutions: applications to the Human Genome Project

    NASA Astrophysics Data System (ADS)

    Williams, Peter W.; Schieltz, David; Nelson, Randall W.; Chou, Chau-Wen; Luo, Cong-Wen; Thomas, Robert

    1993-06-01

    Techniques have been developed to volatilize intact massive DNA molecules using pulsed laser ablation of thin frozen films of aqueous DNA solutions. Electrophoresis assay of the ablated DNA shows that molecules as massive as approximately 400,000 Da can be ablated intact. It has been possible to obtain time-of-flight mass spectra of ablated multicomponent mixtures of single-stranded DNA with masses up to approximately 18,000 Da (a 60-nucleotide DNA oligomer). The possible application of time-of-flight mass spectrometry to the analysis and readout of DNA sequence mixtures, and the potential thereby to accelerate the Human Genome project, are discussed.

  14. Solid Phase Microextraction and Miniature Time-of-Flight Mass Spectrometer

    SciTech Connect

    Hiller, j.m.

    1999-01-26

    A miniature mass spectrometer, based on the time-of-flight principle, has been developed for the detection of chemical warfare agent precursor molecules. The instrument, with minor modifications, could fulfill many of the needs for sensing organic molecules in various Defense Programs, including Enhanced Surveillance. The basic footprint of the instrument is about that of a lunch box. The instrument has a mass range to about 300, has parts-per-trillion detection limits, and can return spectra in less than a second. The instrument can also detect permanent gases and is especially sensitive to hydrogen. In volume, the device could be manufactured for under $5000.

  15. Biomark/Organic Analysis with Time-of-Flight Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Waite, J. Hunter, Jr.

    2004-01-01

    The concept of a Comprehensive 2-Dimensional Gas Chromatography coupled with Time-of-Flight Mass Spectrometry (GCxGC-TOWS) for the analysis of organic compounds has been proven with commercially available instrumentation (LECO Corp). The performance of a GCxGC instrument has been characterized in various stages using two independent breadboard systems. The GCxGC separation systems, including the thermal modulator, have been miniaturized to the size of a benchtop configuration. One breadboard system employs a Flame Ionization Detector (FID), whereas the second breadboard system employs a Time-of-Fight mass spectrometer (TOFWS) as a detection system.

  16. Fourier transform ion cyclotron resonance versus time of flight for precision mass measurements

    SciTech Connect

    Kouzes, R.T.

    1993-02-01

    Both Fourier Transform Ion Cyclotron Resonance and ICR Time-of-Flight mass spectroscopy (FTICR-MS and ICR-TOF-MS, respectively) have been applied to precision atomic mass measurements. This paper reviews the status of these approaches and compares their limitations. Comparisons are made of FTICR-MS and ICR-TOF-MS for application to precision atomic mass measurements of stable and unstable nuclei, where the relevant scale is an accuracy of 1 keV and where halflives are longer than 10 milliseconds (optimistically). The atomic mass table is built up from mass chains, and ICR-MS brings a method of producing new types of mass chains to the mass measurement arena.

  17. Tandem time-of-flight mass spectrometer for cluster--surface scattering experiments

    SciTech Connect

    Beck, R.D.; Weis, P.; Braeuchle, G.; Rockenberger, J.

    1995-08-01

    A new tandem time-of-flight mass spectrometer is described which is designed to study the mass-, velocity-, and angle-resolved scattering of cluster ions from solid surfaces. Clusters are produced in a supersonic jet laser desorption/vaporization source, ionized either directly in the formation step or by subsequent photoionization of neutrals, mass selected in a primary time-of-flight region, and decelerated to the impact energy (50--1000 eV) close to the target surface. Cluster--surface collisions take place in a field-free region in order to determine both velocity and angular distributions of the scattered clusters and fragments with an independently pulsed, rotatable secondary time-of-flight mass spectrometer. Several surface targets can be mounted in the UHV scattering chamber (10{sup {minus}10} Torr base pressure) on a five-axis manipulator which, together with the rotatable secondary TOF, allows for independent variation of incident and scattering angles. Target surfaces can be cleaned by direct current heating and sputtering with an argon-ion gun. Surface structure and composition are assessed by low-energy electron diffraction (LEED) and Auger spectroscopy with a four grid reverse view LEED/Auger system. Surface collision experiments of fullerenes (C{sup +}{sub 60}, C{sup +}{sub 70}, C{sup +}{sub 76}, C{sup +}{sub 84}, ...) and metallofullerenes (La{at}C{sup +}{sub 82}) with highly oriented pyrolitic graphite (HOPG) surfaces are described as examples for the performance of the instrument. Effects of surface contamination in the scattering of fullerenes from HOPG are described to demonstrate the need for thorough cleaning procedures in order to obtain reproducible results. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  18. Detector response in time-of-flight mass spectrometry at high pulse repetition frequencies

    NASA Technical Reports Server (NTRS)

    Gulcicek, Erol E.; Boyle, James G.

    1993-01-01

    Dead time effects in chevron configured dual microchannel plates (MCPs) are investigated. Response times are determined experimentally for one chevron-configured dual MCP-type detector and two discrete dynode-type electron multipliers with 16 and 23 resistively divided stages. All of these detectors are found to be suitable for time-of-flight mass spectrometry (TOF MS), yielding 3-6-ns (FWHM) response times triggered on a single ion pulse. It is concluded that, unless there are viable solutions to overcome dead time disadvantages for continuous dynode detectors, suitable discrete dynode detectors for TOF MS appear to have a significant advantage for high repetition rate operation.

  19. A new design of ion storage accelerator for time-of-flight-MS

    SciTech Connect

    Kraft, A.; Wollnik, H.; Laiko, V.; Dodonov, A.F.

    1995-12-31

    A new Time-of-Flight MS for orthogonal extraction has been constructed. It consists of a API-source, the orthogonal extraction optic and a single stage reflectron as well as a detector with two MCP`s in Chevron-arrangement. The extraction optic has a new design in respect to the prevention of disturbing fields. Such fields take influence on the primary beam during accumulation made and causes noise as well as broadening of mass peaks. This fields arises from the penetration of field through the grid between the two stages of the extraction optic. In this construction, this penetration is compensated by the introduction of an additional electrode which is held at the average virtual potential of the separation grid. By adjusting all electrical parameters of the mass spectrometer (extraction-pulser, backplane of reflector, focussing optics) the peakwidth had been optimized. It has been shown the peakwidth strongly depends on the potential of the compensation electrode. The optimal value corresponds in good agreement with the calculated value (1.7V instead of 1.56V). In the case of Gramicidin S (m=1140) a resolving power of 2000 is achieved.

  20. Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectra of poly(butylene adipate).

    PubMed

    Rizzarelli, Paola; Puglisi, Concetto; Montaudo, Giorgio

    2006-01-01

    Matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS/MS) was employed to analyze four poly(butylene adipate) (PBAd) oligomers and to investigate their fragmentation pathways as a continuation of our work on the MALDI-TOF/TOF-MS/MS study of synthetic polymers. MALDI-TOF/TOF-MS/MS analysis was performed on oligomers terminated by carboxyl and hydroxyl groups, methyl adipate and hydroxyl groups, dihydroxyl groups, and dicarboxyl groups. The sodium adducts of these oligomers were selected as precursor ions. Different end groups do not influence the fragmentation of sodiated polyester oligomers and similar series of product ions were observed in all the MALDI-TOF/TOF-MS/MS spectra. According to the structures of the most abundant product ions identified in the present work, three fragmentation pathways have been proposed to occur most frequently in PBAd: beta-hydrogen-transfer rearrangement, leading to the selective cleavage of the --O--CH(2)-- bonds; --CH(2)--CH(2)-- (beta--beta) bond cleavage in the adipate moiety; and ester bond scission.

  1. Airborne nanoparticle characterization with a digital ion trap-reflectron time of flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Wang, Shenyi; Johnston, Murray V.

    2006-12-01

    A digital ion trap-reflectron time of flight mass spectrometer is described for airborne nanoparticle characterization. Charged particles sampled into this nanoaerosol mass spectrometer (NAMS) are captured in the ion trap and ablated with a high fluence laser pulse to reach the "complete ionization limit". Atomic ions produced from the trapped particle(s) are mass analyzed by time of flight, and the elemental composition is determined from the relative signal intensities in the mass spectrum. The particle size range captured in the ion trap is selected by the frequency applied to the ring electrode. Size selection is based on the mass normalized particle diameter, defined as the diameter of a spherical particle with unit density that has the same mass as the particle being analyzed. For the current instrument configuration, ring electrode frequencies between 5 and 140 kHz allow selective trapping of particles with a mass normalized diameter between 7 and 25 nm with a geometric standard deviation of about 1.1. The particle detection efficiency, defined as the fraction of charged particles entering the mass spectrometer that are subsequently captured and analyzed, is between l x l0-4 and 3 x l0-4 over this size range. The effective particle density can be determined from simultaneous measurement of the mobility and mass normalized diameters. Test nanoparticles composed of sucrose, polyethylene glycol, polypropylene glycol, sodium chloride, ammonium sulfate and copper(II) chloride are investigated. In most cases, the measured elemental compositions match the expected elemental compositions within +/-5% or less and the measured compositions do not change with particle size. The one exception is copper chloride, which does not yield a well-developed plasma when it is irradiated by the laser pulse.

  2. High precision electric gate for time-of-flight ion mass spectrometers

    NASA Technical Reports Server (NTRS)

    Sittler, Edward C. (Inventor)

    2011-01-01

    A time-of-flight mass spectrometer having a chamber with electrodes to generate an electric field in the chamber and electric gating for allowing ions with a predetermined mass and velocity into the electric field. The design uses a row of very thin parallel aligned wires that are pulsed in sequence so the ion can pass through the gap of two parallel plates, which are biased to prevent passage of the ion. This design by itself can provide a high mass resolution capability and a very precise start pulse for an ion mass spectrometer. Furthermore, the ion will only pass through the chamber if it is within a wire diameter of the first wire when it is pulsed and has the right speed so it is near all other wires when they are pulsed.

  3. Delayed bunching for multi-reflection time-of-flight mass separation

    SciTech Connect

    Rosenbusch, M.; Marx, G.; Schweikhard, L.; Wienholtz, F.; Chauveau, P.; Delahaye, P.

    2015-06-29

    Many experiments are handicapped when the ion sources do not only deliver the ions of interest but also contaminations, i.e., unwanted ions of similar mass. In the recent years, multi-reflection time-of-flight mass separation has become a promising method to isolate the ions of interest from the contaminants, in particular for measurements with low-energy short-lived nuclides. To further improve the performance of multi-reflection mass separators with respect to the limitations by space-charge effects, the simultaneously trapped ions are spatially widely distributed in the apparatus. Thus, the ions can propagate with reduced Coulomb interactions until, finally, they are bunched by a change in the trapping conditions for high-resolution mass separation. Proof-of-principle measurements are presented.

  4. Molecular structure of fulvic acids by electrospray with quadrupole time-of-flight mass spectrometry.

    PubMed

    Plancque, G; Amekraz, B; Moulin, V; Toulhoat, P; Moulin, C

    2001-01-01

    Characterisation of the molecular structure of aquatic fulvic acids (FA) has been performed using a quadrupole time-of-flight (Q-TOF) mass spectrometer equipped with an electrospray ionisation interface. Molecular masses centred around 450 Da and sinusoidal spectral distributions have been obtained for all fulvic acids. Tandem mass spectrometry (MS/MS) experiments showed losses of 18 Da (H(2)O) and 44 Da (CO(2)), and possible molecular structures were determined for the first time to our knowledge. A methodology is reported for evaluating the average elemental composition of FA from high-resolution mass spectra by processing post-acquisition data calculations using molecular size distributions and atomic compositions of ions. The results are found to be consistent with elemental analysis data.

  5. Characterization of gunpowder samples using time-of-flight secondary ion mass spectrometry (TOF-SIMS).

    PubMed

    Mahoney, Christine M; Gillen, Greg; Fahey, Albert J

    2006-04-20

    Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was utilized to obtain characteristic mass spectra from three different smokeless powders and six different black powder samples. In these mass spectra, peaks indicative of both the organic and inorganic additive constituents in the gunpowders were observed. TOF-SIMS was able to successfully differentiate between the different black and smokeless gunpowder samples analyzed with the aid of principal components analysis (PCA), a multivariate statistical analysis approach often used to reduce the dimensionality of complex data. TOF-SIMS was also used to obtain information about the spatial distribution of the various additives contained within the gunpowder samples. SIMS imaging demonstrated that that the samples could potentially be characterized by their 2-D structure, which varied from sample to sample. These results clearly demonstrate the feasibility of utilizing TOF-SIMS as a tool for the characterization and differentiation of gunpowder samples for general forensic applications.

  6. Parallel Configuration For Fast Superconducting Strip Line Detectors With Very Large Area In Time Of Flight Mass Spectrometry

    SciTech Connect

    Casaburi, A.; Zen, N.; Suzuki, K.; Ohkubo, M.; Ejrnaes, M.; Cristiano, R.; Pagano, S.

    2009-12-16

    We realized a very fast and large Superconducting Strip Line Detector based on a parallel configuration of nanowires. The detector with size 200x200 {mu}m{sup 2} recorded a sub-nanosecond pulse width of 700 ps in FWHM (400 ps rise time and 530 ps relaxation time) for lysozyme monomers/multimers molecules accelerated at 175 keV in a Time of Flight Mass Spectrometer. This record is the best in the class of superconducting detectors and comparable with the fastest NbN superconducting single photon detector of 10x10 {mu}m{sup 2}. We succeeded in acquiring mass spectra as the first step for a scale-up to {approx}mm pixel size for high throughput MS analysis, while keeping a fast response.

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

    SciTech Connect

    Prather, K.A.; Noble, C.; Salt, K.; Nordmeyer, T.; Fergenson, D.; Morrical, B.

    1995-12-31

    Particulate pollution is an area of growing concern in light of recent studies which suggest a link between high concentrations of ambient PM{sub 10} (particles with diameters equal to or less than 10 {mu}m) and adverse health effects ranging from respiratory ailments to premature death. However, analytical chemistry techniques aimed at sampling and analysis of atmospheric aerosols are extremely limited in comparison to the number of methods that exist for studying gas phase smog components. As a result, current government regulations for levels of ambient particulates are necessarily general, lacking any chemical specificity. The authors have recently developed a technique, Aerosol-Time-of-Flight Mass Spectrometry (ATOFMS), which is capable of real-time determination of the size and chemical composition of individual aerosol particles. In order to obtain such information, the techniques of aerodynamic particle sizing and time-of-flight spectrometry are combined in a single instrument. In one of the aerosol studies performed in this laboratory, this instrument is being used for the direct analysis of ambient aerosols with the goal of establishing correlations between particle size and chemical composition. To date, the authors have observed very distinct size/composition correlations for organic and inorganic particles.

  8. Laser Time-of-Flight Mass Spectrometry for Future In Situ Planetary Missions

    NASA Technical Reports Server (NTRS)

    Getty, S. A.; Brinckerhoff, W. B.; Cornish, T.; Ecelberger, S. A.; Li, X.; Floyd, M. A. Merrill; Chanover, N.; Uckert, K.; Voelz, D.; Xiao, X.; Tawalbeh, R.; Glenar, D.; Elsila, J. E.; Callahan, M.

    2012-01-01

    Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) is a versatile, low-complexity instrument class that holds significant promise for future landed in situ planetary missions that emphasize compositional analysis of surface materials. Here we describe a 5kg-class instrument that is capable of detecting and analyzing a variety of analytes directly from rock or ice samples. Through laboratory studies of a suite of representative samples, we show that detection and analysis of key mineral composition, small organics, and particularly, higher molecular weight organics are well suited to this instrument design. A mass range exceeding 100,000 Da has recently been demonstrated. We describe recent efforts in instrument prototype development and future directions that will enhance our analytical capabilities targeting organic mixtures on primitive and icy bodies. We present results on a series of standards, simulated mixtures, and meteoritic samples.

  9. Depth profiling and imaging capabilities of an ultrashort pulse laser ablation time of flight mass spectrometer

    PubMed Central

    Cui, Yang; Moore, Jerry F.; Milasinovic, Slobodan; Liu, Yaoming; Gordon, Robert J.; Hanley, Luke

    2012-01-01

    An ultrafast laser ablation time-of-flight mass spectrometer (AToF-MS) and associated data acquisition software that permits imaging at micron-scale resolution and sub-micron-scale depth profiling are described. The ion funnel-based source of this instrument can be operated at pressures ranging from 10−8 to ∼0.3 mbar. Mass spectra may be collected and stored at a rate of 1 kHz by the data acquisition system, allowing the instrument to be coupled with standard commercial Ti:sapphire lasers. The capabilities of the AToF-MS instrument are demonstrated on metal foils and semiconductor wafers using a Ti:sapphire laser emitting 800 nm, ∼75 fs pulses at 1 kHz. Results show that elemental quantification and depth profiling are feasible with this instrument. PMID:23020378

  10. Quantitative analysis of biomolecules by time-of-flight secondary-ion mass spectrometry: Fundamental considerations

    SciTech Connect

    Muddiman, D.C.; Nicola, A.J.; Proctor, A.

    1995-12-31

    Static Time-of-Flight Secondary-Ion Mass Spectrometry (TOF-SIMS) has been applied to investigate an extensive assortment of analytical systems; from semiconductors to DNA sequencing. Recently, the TOF-SIMS method has been successfully applied to real biological systems. This report focuses on some important aspects that must be taken into consideration when conducting measurements on biomaterials in order to observe the potential the TOF-SIMS method affords. The current data are presented using Cyclosporin A (CsA, 1202 Da) and cocaine (303 Da) as model compounds. CsA is observed in the TOF-SIMS mass spectrum predominately as a Ag-cationized species and cocaine as a protonated species; thus, they are complementary probe molecules.

  11. Automated Gain Control Ion Funnel Trap for Orthogonal Time-of-Flight Mass Spectrometry

    PubMed Central

    Ibrahim, Yehia M.; Belov, Mikhail E.; Liyu, Andrei V.; Smith, Richard D.

    2009-01-01

    Time-of-flight mass spectrometry (TOF MS) is increasingly used in proteomics research. Herein, we report on the development and characterization of a TOF MS instrument with improved sensitivity equipped with an electrodynamic ion funnel trap (IFT) that employs an automated gain control (AGC) capability. The IFT-TOF MS was coupled to a reversed-phase capillary liquid chromatography (RPLC) separation and evaluated in experiments with complex proteolytic digests. When applied to a global tryptic digest of Shewanella oneidensis proteins, an order-of-magnitude increase in sensitivity compared to that of the conventional continuous mode of operation was achieved due to efficient ion accumulation prior to TOF MS analysis. As a result of this sensitivity improvement and related improvement in mass measurement accuracy, the number of unique peptides identified in the AGC-IFT mode was 5-fold greater than that obtained in the continuous mode. PMID:18512944

  12. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

    SciTech Connect

    Andersen, T.; Jensen, R.; Christensen, M. K.; Chorkendorff, I.; Pedersen, T.; Hansen, O.

    2012-07-15

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/{Delta}m > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH{sub 3}.

  13. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors.

    PubMed

    Andersen, T; Jensen, R; Christensen, M K; Pedersen, T; Hansen, O; Chorkendorff, I

    2012-07-01

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal response. Gas analysis is performed with a time of flight mass spectrometer with a modified nude Bayard-Alpert ionization gauge as gas ionization source. The mass resolution of the time of flight mass spectrometer using the ion gauge as ionization source is estimated to m/Δm > 2500. The system design is superior to conventional batch and flow reactors with accompanying product detection by quadrupole mass spectrometry or gas chromatography not only due to the high sensitivity, fast temperature response, high mass resolution, and fast acquisition time of mass spectra but it also allows wide mass range (0-5000 amu in the current configuration). As a demonstration of the system performance we present data from ammonia oxidation on a Pt thin film showing resolved spectra of OH and NH(3).

  14. Characterization of mustard seeds and paste by DART ionization with time-of-flight mass spectrometry.

    PubMed

    Prchalová, Jana; Kovařík, František; Ševčík, Rudolf; Čížková, Helena; Rajchl, Aleš

    2014-09-01

    Direct analysis in real time (DART) is a novel technique with great potential for rapid screening analysis. The DART ionization method coupled with high-resolution time-of-flight mass spectrometry (TOF-MS) has been used for characterization of mustard seeds and table mustard. The possibility to use DART to analyse glucosinolates was confirmed on determination of sinalbin (4-hydroxybenzyl glucosinolate). The DART-TOF-MS method was optimized and validated. A set of samples of mustard seeds and mustard products was analyzed. High-performance liquid chromatography and DART-TOF-MS were used to determine glucosinolates in mustard seeds and compared. The correlation equation between these methods was DART = 0.797*HPLC + 6.987, R(2)  = 0.972. The DART technique seems to be a suitable method for evaluation of the quality of mustard seeds and mustard products. PMID:25230177

  15. Multiphoton Ionization Time-of-Flight Mass Spectrometry for the Detection of Bioactive Lignan.

    PubMed

    Uchimura, Tomohiro; Tokumoto, Goro; Batnyam, Onon; Chou, Chih-Wei; Fujita, Satoshi

    2016-01-01

    Multiphoton ionization time-of-flight mass spectrometry (MPI-TOFMS) combined with a pulsed laser for sample vaporization was developed for the detection of a low-volatile compound in a solution. A solution containing Taiwanin A ((3E,4E)-3,4-bis(1,3-benzodioxol-5-ylmethylene)dihydro-2(3H)-furanone), which is a lignan that has an anticancer effect, was employed in the present study. Consequently, Taiwanin A could be detected by irradiating a laser pulse for vaporization to an inlet nozzle, rather than by heating. Therefore, the present method could be effective for detecting compounds with lower volatilities in a liquid sample. PMID:26860576

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

    PubMed

    Šedo, Ondrej; Márová, Ivana; Zdráhal, Zbyněk

    2012-11-15

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

  17. Campaign 1.7 Pu Aging. Development of Time of Flight Secondary Ion Mass Spectroscopy

    SciTech Connect

    Venhaus, Thomas J.

    2015-09-09

    The first application of Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) to an aged plutonium surface has resulted in a rich set of surface chemistry data, as well as some unexpected results. FY15 was highlighted by not only the first mapping of hydrogen-containing features within the metal, but also a prove-in series of experiments using the system’s Sieverts Reaction Cell. These experiments involved successfully heating the sample to ~450 oC for nearly 24 hours while the sample was dosed several times with hydrogen, followed by an in situ ToF-SIMS analysis. During this year, the data allowed for better and more consistent identification of the myriad peaks that result from the SIMS sputter process. In collaboration with the AWE (U.K), the system was also fully aligned for sputter depth profiling for future experiments.

  18. TOFwave: reproducibility in biomarker discovery from time-of-flight mass spectrometry data.

    PubMed

    Chierici, Marco; Albanese, Davide; Franceschi, Pietro; Furlanello, Cesare

    2012-11-01

    Many are the sources of variability that can affect reproducibility of disease biomarkers from time-of-flight (TOF) Mass Spectrometry (MS) data. Here we present TOFwave, a complete software pipeline for TOF-MS biomarker identification, that limits the impact of parameter tuning along the whole chain of preprocessing and model selection modules. Peak profiles are obtained by a preprocessing based on Continuous Wavelet Transform (CWT), coupled with a machine learning protocol aimed at avoiding selection bias effects. Only two parameters (minimum peak width and a signal to noise cutoff) have to be explicitly set. The TOFwave pipeline is built on top of the mlpy Python package. Examples on Matrix-Assisted Laser Desorption and Ionization (MALDI) TOF datasets are presented. Software prototype, datasets and details to replicate results in this paper can be found at http://mlpy.sf.net/tofwave/. PMID:22875362

  19. Probing nanoparticles and nanoparticle-conjugated biomolecules using time-of-flight secondary ion mass spectrometry.

    PubMed

    Kim, Young-Pil; Shon, Hyun Kyong; Shin, Seung Koo; Lee, Tae Geol

    2015-01-01

    Bio-conjugated nanoparticles have emerged as novel molecular probes in nano-biotechnology and nanomedicine and chemical analyses of their surfaces have become challenges. The time-of-flight (TOF) secondary ion mass spectrometry (SIMS) has been one of the most powerful surface characterization techniques for both nanoparticles and biomolecules. When combined with various nanoparticle-based signal enhancing strategies, TOF-SIMS can probe the functionalization of nanoparticles as well as their locations and interactions in biological systems. Especially, nanoparticle-based SIMS is an attractive approach for label-free drug screening because signal-enhancing nanoparticles can be designed to directly measure the enzyme activity. The chemical-specific imaging analysis using SIMS is also well suited to screen nanoparticles and nanoparticle-biomolecule conjugates in complex environments. This review presents some recent applications of nanoparticle-based TOF-SIMS to the chemical analysis of complex biological systems.

  20. Analysis of liposome model systems by time-of-flight secondary ion mass spectrometry

    PubMed Central

    Lovrić, Jelena; Keighron, Jacqueline D.; Angerer, Tina B.; Li, Xianchan; Malmberg, Per; Fletcher, John S.; Ewing, Andrew G.

    2015-01-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is an important technique for studying chemical composition of micrometer scale objects due to its high spatial resolution imaging capabilities and chemical specificity. In this work we focus on the application of ToF-SIMS to gain insight into the chemistry of micrometer size liposomes as a potential model for neurotransmitter vesicles. Two models of giant liposomes were analyzed: histamine and aqueous two phase system (ATPS)-containing liposomes. Characterization of the internal structure of single fixed liposomes was done both with the Bi3+ and C60+ ion sources. The depth profiling capability of ToF-SIMS was used to investigate the liposome interior. PMID:25918450

  1. Optimizing sequence coverage for a moderate mass protein in nano-electrospray ionization quadrupole time-of-flight mass spectrometry.

    PubMed

    Matsuda, Ryan; Kolli, Venkata; Woods, Megan; Dodds, Eric D; Hage, David S

    2016-09-15

    Sample pretreatment was optimized to obtain high sequence coverage for human serum albumin (HSA, 66.5 kDa) when using nano-electrospray ionization quadrupole time-of-flight mass spectrometry (nESI-Q-TOF-MS). Use of the final method with trypsin, Lys-C, and Glu-C digests gave a combined coverage of 98.8%. The addition of peptide fractionation resulted in 99.7% coverage. These results were comparable to those obtained previously with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The sample pretreatment/nESI-Q-TOF-MS method was also used with collision-induced dissociation to analyze HSA digests and to identify peptides that could be employed as internal mass calibrants in future studies of modifications to HSA.

  2. Kinetic energy analysis in time of flight mass spectrometry: application of time of flight methods to clusters and pyrolysis studies in supersonic expansions

    NASA Astrophysics Data System (ADS)

    Riley, John S.; Baer, Tomas

    1994-02-01

    A new experimental technique, based on high resolution time of flight analysis of ions in a molecular beam, is described with the use of several examples. Although the approach used here is based on threshold photoelectron photoion coincidence (TPEPICO), the technique can also be used with pulsed laser photoionization, albeit without the benefit of ion energy selection. The approach is based on the fact that the TOF distribution of parent ions formed from cold neutral molecules are narrow, while product ion TOF distributions are broad due to kinetic energy release. This distinction permits differentiating cluster ions formed by "simple" ionization of the corresponding neutral clusters from similar mass cluster ions formed by dissociative ionization. Results so far obtained indicate that most clusters ionize, even at threshold, via dissociative ionization. The technique is also suitable for obtaining the threshold photoelectron spectra (TPES) of mass selected cold species in the presence of a mixture of warm and cold species as might be encountered in a pyrolysis experiment.

  3. Development and characterization of an aircraft aerosol time-of-flight mass spectrometer.

    PubMed

    Pratt, Kerri A; Mayer, Joseph E; Holecek, John C; Moffet, Ryan C; Sanchez, Rene O; Rebotier, Thomas P; Furutani, Hiroshi; Gonin, Marc; Fuhrer, Katrin; Su, Yongxuan; Guazzotti, Sergio; Prather, Kimberly A

    2009-03-01

    Vertical and horizontal profiles of atmospheric aerosols are necessary for understanding the impact of air pollution on regional and global climate. To gain further insight into the size-resolved chemistry of individual atmospheric particles, a smaller aerosol time-of-flight mass spectrometer (ATOFMS) with increased data acquisition capabilities was developed for aircraft-based studies. Compared to previous ATOFMS systems, the new instrument has a faster data acquisition rate with improved ion transmission and mass resolution, as well as reduced physical size and power consumption, all required advances for use in aircraft studies. In addition, real-time source apportionment software allows the immediate identification and classification of individual particles to guide sampling decisions while in the field. The aircraft (A)-ATOFMS was field-tested on the ground during the Study of Organic Aerosols in Riverside, CA (SOAR) and aboard an aircraft during the Ice in Clouds Experiment-Layer Clouds (ICE-L). Initial results from ICE-L represent the first reported aircraft-based single-particle dual-polarity mass spectrometry measurements and provide an increased understanding of particle mixing state as a function of altitude. Improved ion transmission allows for the first single-particle detection of species out to approximately m/z 2000, an important mass range for the detection of biological aerosols and oligomeric species. In addition, high time resolution measurements of single-particle mixing state are demonstrated and shown to be important for airborne studies where particle concentrations and chemistry vary rapidly.

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

    SciTech Connect

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

    2014-10-01

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

  5. Herbal medicine analysis by liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    Zhou, Jian-Liang; Qi, Lian-Wen; Li, Ping

    2009-10-30

    The fact that the effects of herbal medicines (HMs) are brought about by their chemical constituents has created a critical demand for powerful analytical tools performing the chemical analysis to assure their efficacy, safety and quality. Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to analyze multi-components in complex herbal matrices. Due to its inherent characteristics of accurate mass measurements and high resolution, time-of-flight (TOF) MS is well-suited to this field, especially for qualitative applications. The purpose of this article is to provide an overview on the potential of TOF, including the hybrid quadrupole- and ion trap-TOF (QTOF and IT-TOF), hyphenated to LC for chemical analysis in HMs or HM-treated biological samples. The peculiarities of LC-(Q/IT)TOF-MS for the analysis of HMs are discussed first, including applied stationary phase, mobile-phase selection, accurate mass measurements, fragmentation and selectivity. The final section is devoted to describing the applicability of LC-(Q/IT)TOF-MS to routine analysis of multi-components, including target and non-target (unknown) compounds, in herbal samples, emphasizing both the advantages and limitations of this approach for qualitative and quantitative purposes. The potential and future trends of fast high-performance liquid chromatography (HPLC) (e.g. rapid resolution LC and ultra-performance LC) coupled to (Q)TOF-MS for chemical analysis of HMs are highlighted.

  6. Determination of triacetone triperoxide using ultraviolet femtosecond multiphoton ionization time-of-flight mass spectrometry.

    PubMed

    Ezoe, Ryota; Imasaka, Tomoko; Imasaka, Totaro

    2015-01-01

    Triacetone triperoxide (TATP), an explosive compound, was measured using gas chromatography combined with multiphoton ionization time-of-flight mass spectrometry (GC/MPI-TOFMS). By decreasing the pulse width of a femtosecond laser from 80 to 35 fs, a molecular ion was drastically enhanced and was measured as one of the major ions in the mass spectrum. The detection limits obtained using the molecular (M(+)) and fragment (C2H3O(+)) ions were similar or slightly superior to those obtained using conventional mass spectrometry based on electron and chemical ionization. In order to improve the reliability, an isotope of TATP, i.e., TATP-d18, was synthesized and used as an internal standard in the trace analysis of TATP in a sample of human blood. TATP could be identified in a two-dimensional display, even though numerous interfering compounds were present in the sample. Acetone, which is frequently used as a solvent in sampling TATP, produced a chemical species with a retention time nearly identical to that of TATP and provided a C2H3O(+) fragment ion that was employed for measuring a chromatogram of TATP in conventional MS. This compound, the structure of which was assigned as phorone, was clearly differentiated from TATP based on a molecular ion observable in MPI-TOFMS. PMID:25467497

  7. Time-of-flight secondary neutral & ion mass spectrometry using swift heavy ions

    NASA Astrophysics Data System (ADS)

    Breuer, L.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

    2015-12-01

    We report on a new time-of-flight (TOF) spectrometer designed to investigate sputtering phenomena induced by swift heavy ions in the electronic stopping regime. In this experiment, particular emphasis is put on the detection of secondary ions along with their emitted neutral counterparts in order to examine the ionization efficiency of the sputtered material. For the detection of neutral species, the system is equipped with a pulsed VUV laser for post-ionization of sputtered neutral atoms and molecules via single photon ionization at a wavelength of 157 nm (corresponding to 7.9 eV photon energy). For alignment purposes and in order to facilitate comparison to nuclear sputtering conditions, the system also includes a 5 keV Ar+ ion beam directed to the same sample area. The instrument has been added to the M1-branch beam line at the German accelerator facility in Darmstadt (GSI) and was tested with 4.8 MeV/u Au26+ ions impinging onto various samples including metals, salts and organic films. It is found that secondary ion and neutral spectra obtained under both bombardment conditions can be acquired in an interleaved manner throughout a single accelerator pulse cycle, thus making efficient use of valuable beam time. In addition, the keV ion beam can be intermittently switched to dc mode between subsequent data acquisition windows and accelerator pulses in order to ensure reproducible surface conditions. For the case of a dynamically sputter cleaned metal surface, comparison of secondary ion and neutral signals obtained under otherwise identical instrumental conditions reveals a nearly identical ionization probability of atoms emitted under electronic and nuclear sputtering conditions.

  8. High Energy Collisions on Tandem Time-of-Flight Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Cotter, Robert J.

    2013-05-01

    Long before the introduction of matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI), Orbitraps, and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were, nonetheless, some clear advantages for sectors over their low collision energy counterparts. Time-of-flight (TOF) mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective, we recount our own journey to produce high performance TOFs and tandem TOFs, describing the basic theory, problems, and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages, and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging, and the characterization of microorganisms.

  9. Highly efficient, selective and sensitive molecular screening of acetylcholinesterase inhibitors of natural origin by solid-phase extraction-liquid chromatography/electrospray ionisation-octopole-orthogonal acceleration time-of-flight-mass spectrometry and novel thin-layer chromatography-based bioautography.

    PubMed

    Mroczek, Tomasz

    2009-03-20

    Highly efficient, selective and sensitive molecular screening of natural acetylcholinesterase (AChE) inhibitors was developed and comprised optimized pressurized liquid extraction (PLE) of plant materials followed by highly selective solid-phase extraction (SPE) using Oasis HLB cartridges. Pure alkaloidal fractions were analyzed by a newly developed high-performance liquid-chromatography (HPLC) on a 3 microm Atlantis HILIC silica stationary phase combined with recently introduced electrospray ionisation (ESI) octopole-orthogonal acceleration time-of-flight (oa TOF)-mass spectrometry (MS) with high mass accuracy (about 2 ppm) and high sensitivity (absolute limit of detection (LOD) for galanthamine was about 43 fg at signal-to-noise 13:1). Moreover, a newly developed and validated TLC-bioautography permit galanthamine sensitivities at pg levels. In this way, more potent than galanthamine AChE inhibitor namely 1,2-dihydrogalanthamine in Narcissus jonquilla 'Pipit' extract could be found (with IC(50) value 0.19 microM lower of about 42% than that of galanthamine).

  10. Time-of-flight accurate mass spectrometry identification of quinoline alkaloids in honey.

    PubMed

    Rodríguez-Cabo, Tamara; Moniruzzaman, Mohammed; Rodríguez, Isaac; Ramil, María; Cela, Rafael; Gan, Siew Hua

    2015-08-01

    Time-of-flight accurate mass spectrometry (TOF-MS), following a previous chromatographic (gas or liquid chromatography) separation step, is applied to the identification and structural elucidation of quinoline-like alkaloids in honey. Both electron ionization (EI) MS and positive electrospray (ESI+) MS spectra afforded the molecular ions (M(.+) and M+H(+), respectively) of target compounds with mass errors below 5 mDa. Scan EI-MS and product ion scan ESI-MS/MS spectra permitted confirmation of the existence of a quinoline ring in the structures of the candidate compounds. Also, the observed fragmentation patterns were useful to discriminate between quinoline derivatives having the same empirical formula but different functionalities, such as aldoximes and amides. In the particular case of phenylquinolines, ESI-MS/MS spectra provided valuable clues regarding the position of the phenyl moiety attached to the quinoline ring. The aforementioned spectral information, combined with retention times matching, led to the identification of quinoline and five quinoline derivatives, substituted at carbon number 4, in honey samples. An isomer of phenyquinoline was also noticed; however, its exact structure could not be established. Liquid-liquid microextraction and gas chromatography (GC) TOF-MS were applied to the screening of the aforementioned compounds in a total of 62 honeys. Species displaying higher occurrence frequencies were 4-quinolinecarbonitrile, 4-quinolinecarboxaldehyde, 4-quinolinealdoxime, and the phenylquinoline isomer. The Pearson test revealed strong correlations among the first three compounds. PMID:26041455

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  12. Aerosol chemical composition in cloud events by high resolution time-of-flight aerosol mass spectrometry.

    PubMed

    Hao, Liqing; Romakkaniemi, Sami; Kortelainen, Aki; Jaatinen, Antti; Portin, Harri; Miettinen, Pasi; Komppula, Mika; Leskinen, Ari; Virtanen, Annele; Smith, James N; Sueper, Donna; Worsnop, Douglas R; Lehtinen, Kari E J; Laaksonen, Ari

    2013-03-19

    This study presents results of direct observations of aerosol chemical composition in clouds. A high-resolution time-of-flight aerosol mass spectrometer was used to make measurements of cloud interstitial particles (INT) and mixed cloud interstitial and droplet residual particles (TOT). The differences between these two are the cloud droplet residuals (RES). Positive matrix factorization analysis of high-resolution mass spectral data sets and theoretical calculations were performed to yield distributions of chemical composition of the INT and RES particles. We observed that less oxidized hydrocarbon-like organic aerosols (HOA) were mainly distributed into the INT particles, whereas more oxidized low-volatile oxygenated OA (LVOOA) mainly in the RES particles. Nitrates existed as organic nitrate and in chemical form of NH(4)NO(3). Organic nitrates accounted for 45% of total nitrates in the INT particles, in clear contrast to 26% in the RES particles. Meanwhile, sulfates coexist in forms of acidic NH(4)HSO(4) and neutralized (NH(4))(2)SO(4). Acidic sulfate made up 64.8% of total sulfates in the INT particles, much higher than 10.7% in the RES particles. The results indicate a possible joint effect of activation ability of aerosol particles, cloud processing, and particle size effects on cloud formation.

  13. Detection of brake wear aerosols by aerosol time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Beddows, D. C. S.; Dall'Osto, M.; Olatunbosun, O. A.; Harrison, Roy M.

    2016-03-01

    Brake dust particles were characterised using an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) operated using two inlet configurations, namely the aerodynamic lens (AFL) inlet and countersunk nozzle inlet. Laboratory studies show that dust particles are characterised by mass spectra containing ions deriving from Fe and Ba and although highly correlated to each other, the Fe and Ba signals were mostly detected using the nozzle inlet with relatively high laser desorption energies. When using the AFL, only [56Fe] and [-88FeO2] ions were observed in brake dust spectra generated using lower laser desorption pulse energies, and only above 0.75 mJ was the [138Ba] ion detected. When used with the preferred nozzle inlet configuration, the [-88FeO2] peak was considered to be the more reliable tracer peak, because it is not present in other types of dust (mineral, tyre, Saharan etc). As shown by the comparison with ambient data from a number of locations, the aerodynamic lens is not as efficient in detecting brake wear particles, with less than 1% of sampled particles attributed to brake wear. Five field campaigns within Birmingham (background, roadside (3) and road tunnel) used the nozzle inlet and showed that dust particles (crustal and road) accounted for between 3.1 and 65.9% of the particles detected, with the remaining particles being made up from varying percentages of other constituents.

  14. Protocol of single cells preparation for time of flight secondary ion mass spectrometry.

    PubMed

    Bobrowska, Justyna; Pabijan, Joanna; Wiltowska-Zuber, Joanna; Jany, Benedykt R; Krok, Franciszek; Awsiuk, Kamil; Rysz, Jakub; Budkowski, Andrzej; Lekka, Malgorzata

    2016-10-15

    There are several techniques like time of flight secondary ion mass spectrometry (ToF SIMS) that require a special protocol for preparation of biological samples, in particular, those containing single cells due to high vacuum conditions that must be kept during the experiment. Frequently, preparation methodology involves liquid nitrogen freezing what is not always convenient. In our studies, we propose and validate a protocol for preparation of single cells. It consists of four steps: (i) paraformaldehyde fixation, (ii) salt removal, (iii) dehydrating, and (iv) sample drying under ambient conditions. The protocol was applied to samples with single melanoma cells i.e. WM115 and WM266-4 characterized by similar morphology. The surface and internal structures of cells were monitored using atomic force, scanning electron and fluorescent microscopes, used to follow any potential protocol-induced alterations. To validate the proposed methodology for sample preparation, ToF SIMS experiments were carried out using C60(+) cluster ion beam. The applied principal component analysis (PCA) revealed that chemical changes on cell surface of melanoma cells were large enough to differentiate between primary and secondary tumor sites. Subject category: Mass spectrometry. PMID:27318241

  15. Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

    PubMed Central

    Huang, Yunguang; Li, Jinxu; Tang, Bin; Zhu, Liping; Hou, Keyong; Li, Haiyang

    2015-01-01

    A vacuum ultraviolet lamp based single photon ionization- (SPI-) photoelectron ionization (PEI) portable reflecting time-of-flight mass spectrometer (TOFMS) was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE) below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX), SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1) with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear. PMID:26587023

  16. Multiplexed Ion Mobility Spectrometry - Orthogonal Time-Of-Flight Mass Spectrometry

    SciTech Connect

    Belov, Mikhail E.; Buschbach, Michael A.; Prior, David C.; Tang, Keqi; Smith, Richard D.

    2007-03-15

    Ion mobility spectrometry (IMS) coupled to orthogonal time-of-flight mass spectrometry (TOF) has shown significant promise for the characterization of complex biological mixtures. The enormous complexity of biological samples (e.g. from proteomics) and the need for both biological and technical analysis replicates imposes major challenges for multidimensional separation platforms in regard to both sensitivity and sample throughput. A major potential attraction of the IMS-TOF MS platform is separation speeds exceeding that of conventional condensed-phase separations by orders of magnitude. Known limitations of the IMS-TOF MS platforms that presently mitigate this attraction include the need for extensive signal averaging due to factors that include significant ion losses in the IMS-TOF interface and an ion utilization efficiency of less than ~1% with continuous ion sources (e.g. ESI). We have developed a new multiplexed ESI-IMS-TOF mass spectrometer that enables lossless ion transmission through the IMS-TOF as well as a utilization efficiency of >50% for ions from the ESI source. Initial results with a mixture of peptides show a ~10-fold increase in signal-to-noise ratio with the multiplexed approach compared to a signal averaging approach, with no reduction in either IMS or TOF MS resolution.

  17. Introduction to time-of-flight secondary ion mass spectrometry application in chromatographic analysis.

    PubMed

    Orinák, Andrej; Arlinghaus, Heinrich F; Vering, Guido; Orináková, Renáta; Hellweg, Sebastian

    2005-08-19

    New on-line analytical system coupling thin layer chromatography (TLC) and high selective identification unit-time of flight secondary ion mass spectrometry (TOF-SIMS) is introduced in this article. Chromatographic mixture separation and analyte surface deposition followed with surface TOF-SIMS analysis on-line allows to identify the analytes at trace and ultratrace levels. The selected analytes with different detectability and identification possibility were analysed in this hyphenated unit (Methyl Red indicator, Terpinolen and Giberrelic acid). Here, the chromatographic thin layer plays a universal role: separation unit, analyte depositing surface and TOF-SIMS interface, finally. Two depositing substrates and TOF-SIMS compatible interfaces were tested in above-mentioned interfacing unit: modified aluminium backed chromatographic thin layer and monolithic silica thin layer. The sets of positive and negative ions TOF-SIMS spectra obtained from different SIMS modes of analysis were used for analyte identification purposes. SIMS enables analyte detection with high mass resolution at the concentration level that is not achieved by other methods. PMID:16114244

  18. Laser photoionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons and nitrated heterocyclic compounds. Master's thesis

    SciTech Connect

    Noyes, R.A.

    1993-01-01

    Partial Contents: Laser Desorption-Laser Photoionization Time-of-Flight Mass Spectrometry; Basic Principles of TOFMS; Factors Affecting Flight Time; Source of Broadening; Laser Desorption; Theory of Multiphoton Ionization: Application to Mass Spectrometry; Quantum Theory of MPI; Time-Dependent Perturbation Theory; Time-Dependent Coefficients; Probability of a Two-Photon Process; and Attributes of R2PI.

  19. Development of analytically capable time-of-flight mass spectrometer with continuous ion introduction.

    PubMed

    Hárs, György; Dobos, Gábor

    2010-03-01

    The present article describes the results and findings explored in the course of the development of the analytically capable prototype of continuous time-of-flight (CTOF) mass spectrometer. Currently marketed pulsed TOF (PTOF) instruments use ion introduction with a 10 ns or so pulse width, followed by a waiting period roughly 100 micros. Accordingly, the sample is under excitation in 10(-4) part of the total measuring time. This very low duty cycle severely limits the sensitivity of the PTOF method. A possible approach to deal with this problem is to use linear sinusoidal dual modulation technique (CTOF) as described in this article. This way the sensitivity of the method is increased, due to the 50% duty cycle of the excitation. All other types of TOF spectrometer use secondary electron multiplier (SEM) for detection, which unfortunately discriminates in amplification in favor of the lighter ions. This discrimination effect is especially undesirable in a mass spectrometric method, which targets high mass range. In CTOF method, SEM is replaced with Faraday cup detector, thus eliminating the mass discrimination effect. Omitting SEM is made possible by the high ion intensity and the very slow ion detection with some hundred hertz detection bandwidth. The electrometer electronics of the Faraday cup detector operates with amplification 10(10) V/A. The primary ion beam is highly monoenergetic due to the construction of the ion gun, which made possible to omit any electrostatic mirror configuration for bunching the ions. The measurement is controlled by a personal computer and the intelligent signal generator Type Tabor WW 2571, which uses the direct digital synthesis technique for making arbitrary wave forms. The data are collected by a Labjack interface board, and the fast Fourier transformation is performed by the software. Noble gas mixture has been used to test the analytical capabilities of the prototype setup. Measurement presented proves the results of the

  20. Development of analytically capable time-of-flight mass spectrometer with continuous ion introduction

    SciTech Connect

    Hars, Gyoergy; Dobos, Gabor

    2010-03-15

    The present article describes the results and findings explored in the course of the development of the analytically capable prototype of continuous time-of-flight (CTOF) mass spectrometer. Currently marketed pulsed TOF (PTOF) instruments use ion introduction with a 10 ns or so pulse width, followed by a waiting period roughly 100 {mu}s. Accordingly, the sample is under excitation in 10{sup -4} part of the total measuring time. This very low duty cycle severely limits the sensitivity of the PTOF method. A possible approach to deal with this problem is to use linear sinusoidal dual modulation technique (CTOF) as described in this article. This way the sensitivity of the method is increased, due to the 50% duty cycle of the excitation. All other types of TOF spectrometer use secondary electron multiplier (SEM) for detection, which unfortunately discriminates in amplification in favor of the lighter ions. This discrimination effect is especially undesirable in a mass spectrometric method, which targets high mass range. In CTOF method, SEM is replaced with Faraday cup detector, thus eliminating the mass discrimination effect. Omitting SEM is made possible by the high ion intensity and the very slow ion detection with some hundred hertz detection bandwidth. The electrometer electronics of the Faraday cup detector operates with amplification 10{sup 10} V/A. The primary ion beam is highly monoenergetic due to the construction of the ion gun, which made possible to omit any electrostatic mirror configuration for bunching the ions. The measurement is controlled by a personal computer and the intelligent signal generator Type Tabor WW 2571, which uses the direct digital synthesis technique for making arbitrary wave forms. The data are collected by a Labjack interface board, and the fast Fourier transformation is performed by the software. Noble gas mixture has been used to test the analytical capabilities of the prototype setup. Measurement presented proves the results of

  1. Development of analytically capable time-of-flight mass spectrometer with continuous ion introduction

    NASA Astrophysics Data System (ADS)

    Hárs, György; Dobos, Gábor

    2010-03-01

    The present article describes the results and findings explored in the course of the development of the analytically capable prototype of continuous time-of-flight (CTOF) mass spectrometer. Currently marketed pulsed TOF (PTOF) instruments use ion introduction with a 10 ns or so pulse width, followed by a waiting period roughly 100 μs. Accordingly, the sample is under excitation in 10-4 part of the total measuring time. This very low duty cycle severely limits the sensitivity of the PTOF method. A possible approach to deal with this problem is to use linear sinusoidal dual modulation technique (CTOF) as described in this article. This way the sensitivity of the method is increased, due to the 50% duty cycle of the excitation. All other types of TOF spectrometer use secondary electron multiplier (SEM) for detection, which unfortunately discriminates in amplification in favor of the lighter ions. This discrimination effect is especially undesirable in a mass spectrometric method, which targets high mass range. In CTOF method, SEM is replaced with Faraday cup detector, thus eliminating the mass discrimination effect. Omitting SEM is made possible by the high ion intensity and the very slow ion detection with some hundred hertz detection bandwidth. The electrometer electronics of the Faraday cup detector operates with amplification 1010 V/A. The primary ion beam is highly monoenergetic due to the construction of the ion gun, which made possible to omit any electrostatic mirror configuration for bunching the ions. The measurement is controlled by a personal computer and the intelligent signal generator Type Tabor WW 2571, which uses the direct digital synthesis technique for making arbitrary wave forms. The data are collected by a Labjack interface board, and the fast Fourier transformation is performed by the software. Noble gas mixture has been used to test the analytical capabilities of the prototype setup. Measurement presented proves the results of the mathematical

  2. Monoacylglycerol Analysis Using MS/MSALL Quadruple Time of Flight Mass Spectrometry

    PubMed Central

    Gao, Fei; McDaniel, Justice; Chen, Emily Y.; Rockwell, Hannah; Lynes, Matthew D.; Tseng, Yu-Hua; Sarangarajan, Rangaprasad; Narain, Niven R.; Kiebish, Michael A.

    2016-01-01

    Monoacylglycerols (MAGs) are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MSALL, using electrospray ionization (ESI) coupled quadrupole time of flight mass spectrometry (MS), was utilized for the structural identification and quantitative analysis of individual MAG molecular species. Compared with other acylglycerols, diacylglycerols (DAG) and triacylglycerols (TAG), MAG characteristically presented as a dominant protonated ion, [M + H]+, and under low collision energy as fatty acid-like fragments due to the neutral loss of the glycerol head group. At low concentrations (<10 pmol/µL), where lipid-lipid interactions are rare, there was a strong linear correlation between ion abundance and MAG concentration. Moreover, using the MS/MSALL method the major MAG species from human plasma and mouse brown and white adipose tissues were quantified in less than 6 min. Collectively, these results demonstrate that MS/MSALL analysis of MAG is an enabling strategy for the direct identification and quantitative analysis of low level MAG species from biological samples with high throughput and sensitivity. PMID:27548241

  3. Multi-capillary-column proton-transfer-reaction time-of-flight mass spectrometry☆

    PubMed Central

    Ruzsanyi, Veronika; Fischer, Lukas; Herbig, Jens; Ager, Clemes; Amann, Anton

    2013-01-01

    Proton-transfer-reaction time-of-flight mass-spectrometry (PTR-TOFMS) exhibits high selectivity with a resolution of around 5000 m/Δm. While isobars can be separated with this resolution, discrimination of isomeric compounds is usually not possible. The coupling of a multi-capillary column (MCC) with a PTR-TOFMS overcomes these problems as demonstrated in this paper for the ketone isomers 3-heptanone and 2-methyl-3-hexanone and for different aldehydes. Moreover, fragmentation of compounds can be studied in detail which might even improve the identification. LODs for compounds tested are in the range of low ppbv and peak positions of the respective separated substances show good repeatability (RSD of the peak positions <3.2%). Due to its special characteristics, such as isothermal operation, compact size, the MCC setup is suitable to be installed inside the instrument and the overall retention time for a complete spectrum is only a few minutes: this allows near real-time measurements in the optional MCC mode. In contrast to other methods that yield additional separation, such as the use of pre-cursor ions other than H3O+, this method yields additional information without increasing complexity. PMID:24119758

  4. Liquid chromatography quadrupole time-of-flight mass spectrometry selective determination of ochratoxin A in wine.

    PubMed

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Cela, R

    2016-05-15

    The performance of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for ochratoxin A (OTA) determination in wine is evaluated for the first time. Sample preparation was optimized to obtain quantitative recoveries at the same time that the efficiency of electrospray ionization (ESI) remained unaltered between sample extracts and calibration standards. Under final conditions, samples (20 mL) were concentrated using a reversed-phase solid-phase extraction (SPE) cartridge, followed by OTA elution with 1 mL of ethyl acetate. The absolute recoveries of the method, established against calibration standards, were 91-121% and 90-113% (without and with internal standard correction, respectively), for wines fortified at 3 concentration levels. The attained LOQ (0.05 ng mL(-1)) remained below the maximum permitted OTA concentration (2 ng mL(-1)) in dry wines. The method was applied to different samples, with OTA being found in some dessert wines at concentrations below 1 ng mL(-1). The ethyl ester of OTA (OTC) could be identified in the same wine samples from its accurate full product ion spectra.

  5. Comprehensive blood plasma lipidomics by liquid chromatography/quadrupole time-of-flight mass spectrometry.

    PubMed

    Sandra, Koen; Pereira, Alberto Dos Santos; Vanhoenacker, Gerd; David, Frank; Sandra, Pat

    2010-06-18

    A lipidomics strategy, combining high resolution reversed-phase liquid chromatography (RPLC) with high resolution quadrupole time-of-flight mass spectrometry (QqTOF), is described. The method has carefully been assessed in both a qualitative and a quantitative fashion utilizing human blood plasma. The inherent low technical variability associated with the lipidomics method allows to measure 65% of the features with an intensity RSD value below 10%. Blood plasma lipid spike-in experiments demonstrate that relative concentration differences smaller than 25% can readily be revealed by means of a t-test. Utilizing an advanced identification strategy, it is shown that the detected features mainly originate from (lyso-)phospholipids, sphingolipids, mono-, di- and triacylglycerols and cholesterol esters. The high resolution offered by the up-front RPLC step further allows to discriminate various isomeric species associated with the different lipid classes. The added value of utilizing a Jetstream electrospray ionization (ESI) source over a regular ESI source in lipidomics is for the first time demonstrated. In addition, the application of ultra high performance LC (UHPLC) up to 1200bar to extend the peak capacity or increase productivity is discussed. PMID:20307888

  6. Preparation, IR spectroscopy, and time-of-flight mass spectrometry of halogenated and methylated Si(111)

    NASA Astrophysics Data System (ADS)

    Salingue, Nils; Hess, Peter

    2011-09-01

    The preparation of chlorine-, bromine-, and iodine-terminated silicon surfaces (Si(111):Cl, Br, and I) using atomically flat Si(111)-(1×1):H is described. The halogenated surfaces were obtained by photochemically induced radical substitution reactions with the corresponding dihalogen in a Schlenk tube by conventional inert gas chemistry. The nucleophilic substitution of the Si-Cl functionality with the Grignard reagent (CH3MgCl) resulted in the unreconstructed methylated Si(111)-(1×1):CH3 surface. The halogenated and methylated silicon surfaces were characterized by Fourier transform infrared (FTIR) spectroscopy and laser-induced desorption of monolayers (LIDOM). Calibration of the desorption temperature via analysis of time-of-flight (TOF) distributions as a function of laser fluence allowed the determination of the originally emitted neutral fragments by TOF mass spectrometry using electron-impact ionization. The halogens were desorbed atomically and as SiX n (X = Cl, Br) clusters. The methyl groups mainly desorbed as methyl and ethyl fragments and a small amount of +SiCH3.

  7. Monoacylglycerol Analysis Using MS/MS(ALL) Quadruple Time of Flight Mass Spectrometry.

    PubMed

    Gao, Fei; McDaniel, Justice; Chen, Emily Y; Rockwell, Hannah; Lynes, Matthew D; Tseng, Yu-Hua; Sarangarajan, Rangaprasad; Narain, Niven R; Kiebish, Michael A

    2016-01-01

    Monoacylglycerols (MAGs) are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MS(ALL), using electrospray ionization (ESI) coupled quadrupole time of flight mass spectrometry (MS), was utilized for the structural identification and quantitative analysis of individual MAG molecular species. Compared with other acylglycerols, diacylglycerols (DAG) and triacylglycerols (TAG), MAG characteristically presented as a dominant protonated ion, [M + H]⁺, and under low collision energy as fatty acid-like fragments due to the neutral loss of the glycerol head group. At low concentrations (<10 pmol/µL), where lipid-lipid interactions are rare, there was a strong linear correlation between ion abundance and MAG concentration. Moreover, using the MS/MS(ALL) method the major MAG species from human plasma and mouse brown and white adipose tissues were quantified in less than 6 min. Collectively, these results demonstrate that MS/MS(ALL) analysis of MAG is an enabling strategy for the direct identification and quantitative analysis of low level MAG species from biological samples with high throughput and sensitivity. PMID:27548241

  8. Analysis of lung surfactant model systems with time-of-flight secondary ion mass spectrometry.

    PubMed Central

    Bourdos, N; Kollmer, F; Benninghoven, A; Ross, M; Sieber, M; Galla, H J

    2000-01-01

    An often-used model lung surfactant containing dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG), and the surfactant protein C (SP-C) was analyzed as Langmuir-Blodgett film by spatially resolved time-of-flight secondary ion mass spectrometry (TOF-SIMS) to directly visualize the formation and composition of domains. Binary lipid and lipid/SP-C systems were probed for comparison. TOF-SIMS spectra revealed positive secondary ions (SI) characteristic for DPPC and SP-C, but not for DPPG. SI mapping results in images with domain structures in DPPC/DPPG and DPPG/SP-C, but not in DPPC/SP-C films. We are able to distinguish between the fluid and condensed areas probably due to a matrix effect. These findings correspond with other imaging techniques, fluorescence light microscopy (FLM), scanning force microscopy (SFM), and silver decoration. The ternary mixture DPPC/DPPG/SP-C transferred from the collapse region exhibited SP-C-rich domains surrounding pure lipid areas. The results obtained are in full accordance with our earlier SFM picture of layered protrusions that serve as a compressed reservoir for surfactant material during expansion. Our study demonstrates once more that SP-C plays a unique role in the respiration process. PMID:10866961

  9. Investigation of isovaline enantiomeric excesses in CM meteorites using liquid chromatography time of flight mass spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.

    2003-01-01

    The enantiomeric abundances of the alpha-dialkyl amino acid isovaline were measured in the CM2 meteorites Murchison and LEW 90500 using a new liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) technique coupled with OPA/NAC derivatization and UV fluorescence detection. Previous analyses of Murchison have shown that L-enantiomeric excesses of isovaline range from 0 to 15.2% with significant variation between meteorite fragments [1]. For this study, hot water extracts of interior fragments (> 2 cm from fusion crust) of the Murchison (USNM 6650.2, mass 6 g) and LEW 90500 (split 69, parent 1, mass 5 g) carbonaceous meteorites were analyzed. Enantiomeric excesses were measured using the single ion LC-ToF-MS trace for the OPA/NAC derivative of isovaline at d z 393.15 (Fig. 1). L-isovaline excesses in these meteorite samples ranged from 18.9 to 20.5% for Murchison and -0.5 to 3.0% for LEW 90500. The measured values for Murchison are the largest enantiomeric excesses for isovaline reported to date. The enantiomeric excesses of L-isovaline cannot be the result of interference from other C5 amino acid isomers present in the meteorites or terrestrial contamination from the landing site environments. The L-isovaline excesses in Murchison are inconsistent with the synthesis of all of the isovaline by the Strecker-cyanohydrin pathway on the CM meteorite parent body. The mechanism(s) for the formation of the enantiomeric asymmetry in isovaline in Murchison are currently unknown and it is not clear how the asymmetry of alpha-dialkyl amino acids could be transferred to the a-hydrogen protein amino acids common in all life on Earth today.

  10. Nanocluster isotope distributions measured by electrospray time-of-flight mass spectrometry.

    PubMed

    Comeau, Amanda N; Liu, JiangJiang; Khadka, Chhatra B; Corrigan, John F; Konermann, Lars

    2013-01-15

    Electrospray ionization (ESI) mass spectrometry (MS) is a widely used tool for the characterization of organometallic nanoclusters. By matching experimental mass spectra with calculated isotope distributions it is possible to determine the elemental composition of these analytes. In this work we conduct ESI-MS investigations on M(14)E(13)Cl(2)(tmeda)(6) nanoclusters, where M is a transition metal, E represents a chalcogen, and tmeda is N,N,N',N'-tetramethyl-ethylenediamine. ESI mass spectra of these systems agree poorly with theoretical isotope distributions when data are acquired under standard conditions. This behavior is attributed to dead-time artifacts of the time-of-flight (TOF) analyzer used. It is well-known that excessively high TOF ion count rates lead to dead-time issues. Surprisingly, our data reveal that nanocluster spectra are affected by this problem even at moderate signal intensities that do not cause any problems for other types of analytes. This unexpected vulnerability is attributed to the extremely wide isotope distributions of the nanoclusters studied here. A good match between experimental and calculated nanocluster spectra is obtained only at ion count rates that are more than 1 order of magnitude below commonly used levels. Discrepancies between measured and theoretical isotope distributions have been observed in a number of previous ESI-MS nanocluster investigations. The dead-time issue identified here likely represents a contributing factor to the spectral distortions that were observed in those earlier studies. Using low-intensity ESI-MS conditions we demonstrate the feasibility of analyzing highly heterogeneous nanocluster samples that comprise subpopulations with a wide range of metal compositions.

  11. The power of hyphenated chromatography/time-of-flight mass spectrometry in public health laboratories.

    PubMed

    Ibáñez, María; Portolés, Tania; Rúbies, Antoni; Muñoz, Eva; Muñoz, Gloria; Pineda, Laura; Serrahima, Eulalia; Sancho, Juan V; Centrich, Francesc; Hernández, Félix

    2012-05-30

    Laboratories devoted to the public health field have to face the analysis of a large number of organic contaminants/residues in many different types of samples. Analytical techniques applied in this field are normally focused on quantification of a limited number of analytes. At present, most of these techniques are based on gas chromatography (GC) or liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS). Using these techniques only analyte-specific information is acquired, and many other compounds that might be present in the samples would be ignored. In this paper, we explore the potential of time-of-flight (TOF) MS hyphenated to GC or LC to provide additional information, highly useful in this field. Thus, all positives reported by standard reference targeted LC-MS/MS methods were unequivocally confirmed by LC-QTOF MS. Only 61% of positives reported by targeted GC-MS/MS could be confirmed by GC-TOF MS, which was due to its lower sensitivity as nonconfirmations corresponded to analytes that were present at very low concentrations. In addition, the use of TOF MS allowed searching for additional compounds in large-scope screening methodologies. In this way, different contaminants/residues not included in either LC or GC tandem MS analyses were detected. This was the case of the insecticide thiacloprid, the plant growth regulator paclobutrazol, the fungicide prochloraz, or the UV filter benzophenone, among others. Finally, elucidation of unknowns was another of the possibilities offered by TOF MS thanks to the accurate-mass full-acquisition data available when using this technique.

  12. Qualitative nontarget analysis of landfill leachate using gas chromatography time-of-flight mass spectrometry.

    PubMed

    Jernberg, Joonas; Pellinen, Jukka; Rantalainen, Anna-Lea

    2013-01-15

    Nontarget analysis means that a sample is analysed without preselection of the studied analytes. While target analysis attempts to determine whether certain selected compounds are present in the sample, nontarget analysis is performed to explore what unknown compounds can be found. We developed a nontarget method using a landfill leachate sample as a complex test sample. The method was based on the use of a gas chromatograph-time-of-flight mass spectrometer (GC-TOF-MS) for final analysis and a deconvolution computer application for data processing. This nontarget analysis method was tested and validated by applying it to a landfill leachate sample spiked with 11 organic pollutants that were treated as unknowns. Sensitivity was found to be the most critical parameter affecting the success of nontarget analysis. The limit of identification (LOI) was 2500 ng L(-1) for four of the 11 compounds, 500 ng L(-1) for three compounds and 100 ng L(-1) for one compound. Three compounds were not detected in any of the spiked samples. A six-stage identification process was developed based on the spiking experiments. The process was based on the forward fit value of the library hit, the number of deconvoluted ions and the accurate mass scoring of the measured ions. The process was applied to an unspiked leachate water sample. Altogether, 44 compounds were tentatively identified in the sample. Elemental compositions of 36 components were additionally determined for which an unequivocal compound identification could not be given. Nontarget analysis with GC-TOF-MS is a promising method for the qualitative analysis of complex water samples. However, we conclude that the computer application for nontarget analysis needs improvement to decrease the amount of manual work needed in the identification process.

  13. Time-Of-Flight Mass Spectrometry of Laser Exploding Foil Initiated PETN Samples

    NASA Astrophysics Data System (ADS)

    Fajardo, Mario

    2015-06-01

    We report the results of time-of-flight mass spectrometry (TOFMS) measurements of the gaseous products of thin film PETN samples reacting in-vacuo. The PETN sample spots are produced by masked physical vapor deposition of PETN onto a first-surface aluminum mirror. A pulsed laser beam imaged through the soda lime glass mirror substrate converts the aluminum layer into a high-temperature high-pressure plasma which initiates chemical reactions in the overlying PETN sample. We had previously proposed to exploit differences in gaseous product chemical identities and molecular velocities to provide a chemically-based diagnostic for distinguishing between ``detonation-like'' and deflagration responses. Briefly: we expect in-vacuum detonations to produce hyperthermal (v ~ 10 km/s) thermodynamically-stable products such as N2, CO2, and H2O, and for deflagrations to produce mostly reaction intermediates, such as NO and NO2, with much slower molecular velocities - consistent with the expansion-quenched thermal decomposition of PETN. We observe primarily slow reaction intermediates (NO2, CH2NO3) at low laser pulse energies, the appearance of NO at intermediate laser pulse energies, and the appearance of hyperthemal CO/N2 at mass 28 amu at the highest laser pulse energies. However, these results are somewhat ambiguous, as the NO, NO2, and CH2NO3 intermediates persist and all species become hyperthermal at the higher laser pulse energies. Also, the purported CO/N2 signal at 28 amu may be contaminated by silicon ablated from the glass mirror substrate. We plan to mitigate these problems in future experiments by adopting the ``Buelow'' sample configuration which employs an intermediate foil barrier to shield the energetic material from the laser and the laser driven plasma. [RW PA#4930

  14. Accurate characterization of carcinogenic DNA adducts using MALDI tandem time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Barnes, Charles A.; Chiu, Norman H. L.

    2009-01-01

    Many chemical carcinogens and their in vivo activated metabolites react readily with genomic DNA, and form covalently bound carcinogen-DNA adducts. Clinically, carcinogen-DNA adducts have been linked to various cancer diseases. Among the current methods for DNA adduct analysis, mass spectroscopic method allows the direct measurement of unlabeled DNA adducts. The goal of this study is to explore the use of matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to determine the identity of carcinogen-DNA adducts. Two of the known carcinogenic DNA adducts, namely N-(2'-deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (dG-C8-PhIP) and N-(2'-deoxyguanosin-8yl)-4-aminobiphenyl (dG-C8-ABP), were selected as our models. In MALDI-TOF MS measurements, the small matrix ion and its cluster ions did not interfere with the measurements of both selected dG adducts. To achieve a higher accuracy for the characterization of selected dG adducts, 1 keV collision energy in MALDI-TOF/TOF MS/MS was used to measure the adducts. In comparison to other MS/MS techniques with lower collision energies, more extensive precursor ion dissociations were observed. The detection of the corresponding fragment ions allowed the identities of guanine, PhIP or ABP, and the position of adduction to be confirmed. Some of the fragment ions of dG-C8-PhIP have not been reported by other MS/MS techniques.

  15. The power of hyphenated chromatography/time-of-flight mass spectrometry in public health laboratories.

    PubMed

    Ibáñez, María; Portolés, Tania; Rúbies, Antoni; Muñoz, Eva; Muñoz, Gloria; Pineda, Laura; Serrahima, Eulalia; Sancho, Juan V; Centrich, Francesc; Hernández, Félix

    2012-05-30

    Laboratories devoted to the public health field have to face the analysis of a large number of organic contaminants/residues in many different types of samples. Analytical techniques applied in this field are normally focused on quantification of a limited number of analytes. At present, most of these techniques are based on gas chromatography (GC) or liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS). Using these techniques only analyte-specific information is acquired, and many other compounds that might be present in the samples would be ignored. In this paper, we explore the potential of time-of-flight (TOF) MS hyphenated to GC or LC to provide additional information, highly useful in this field. Thus, all positives reported by standard reference targeted LC-MS/MS methods were unequivocally confirmed by LC-QTOF MS. Only 61% of positives reported by targeted GC-MS/MS could be confirmed by GC-TOF MS, which was due to its lower sensitivity as nonconfirmations corresponded to analytes that were present at very low concentrations. In addition, the use of TOF MS allowed searching for additional compounds in large-scope screening methodologies. In this way, different contaminants/residues not included in either LC or GC tandem MS analyses were detected. This was the case of the insecticide thiacloprid, the plant growth regulator paclobutrazol, the fungicide prochloraz, or the UV filter benzophenone, among others. Finally, elucidation of unknowns was another of the possibilities offered by TOF MS thanks to the accurate-mass full-acquisition data available when using this technique. PMID:22578112

  16. High resolution time-of-flight mass analysis of the entire range of intact singly-charged proteins.

    PubMed

    Lee, Jeonghoon; Chen, Huijuan; Liu, Tiancheng; Berkman, Clifford E; Reilly, Peter T A

    2011-12-15

    The proof of principle for high-resolution analysis of intact singly charged proteins of any size is presented. Singly charged protein ions were produced by electrospray ionization followed by surface-induced charge reduction at atmospheric pressure. The inlet and trapping system "stops" the forward momentum of the protein ions over a very broad range to be captured by the digitally produced electric fields of a large radius linear ion trap whereupon they are moved into a smaller radius linear ion trap and collected and concentrated in front of its exit end-cap electrode using digital waveform manipulation. The protein ions are then ejected on demand from the end of the small radius linear quadrupole in a tightly collimated ion beam with an instrumentally defined kinetic energy into the acceleration region of an orthogonal acceleration reflectron time-of-flight mass analyzer where their flight times were measured and detected with a Photonis BiPolar TOF detector. We present results that clearly prove that massive singly charged ions can yield high-resolution mass spectra with very low chemical noise and without loss of sensitivity with increasing mass across the entire spectrum. Analysis of noncovalently bound protein complexes was demonstrated with streptavidin-Cy5 bound with a biotinylated peptide mimic. Our results suggest proteins across the entire range can be directly quantified using our mass analysis technique. We present evidence that solvent molecules noncovalently adduct onto the proteins while yielding consistent flight time distributions. Finally, we provide a look into future that will result from the ability to rapidly measure and quantify protein distributions.

  17. Nanocalorimetry-coupled time-of-flight mass spectrometry: identifying evolved species during high-rate thermal measurements.

    PubMed

    Yi, Feng; DeLisio, Jeffery B; Zachariah, Michael R; LaVan, David A

    2015-10-01

    We report on measurements integrating a nanocalorimeter sensor into a time-of-flight mass spectrometer (TOFMS) for simultaneous thermal and speciation measurements at high heating rates. The nanocalorimeter sensor was incorporated into the extraction region of the TOFMS system to provide sample heating and thermal information essentially simultaneously with the evolved species identification. This approach can be used to measure chemical reactions and evolved species for a variety of materials. Furthermore, since the calorimetry is conducted within the same proximal volume as ionization and ion extraction, evolved species detected are in a collision-free environment, and thus, the possibility exists to interrogate intermediate and radical species. We present measurements showing the decomposition of ammonium perchlorate, copper oxide nanoparticles, and sodium azotetrazolate. The rapid, controlled, and quantifiable heating rate capabilities of the nanocalorimeter coupled with the 0.1 ms temporal resolution of the TOFMS provides a new measurement capability and insight into high-rate reactions, such as those seen with reactive and energetic materials, and adsorption\\desorption measurements, critical for understanding surface chemistry and accelerating catalyst selection. PMID:26372315

  18. Nano-localized desorption and time-of-flight mass analysis using solely optical enhancement in the proximity of a scanning tunneling microscope tip

    NASA Astrophysics Data System (ADS)

    Ding, Yu; Micheletto, Ruggero; Okazaki, Satoshi; Otsuka, Koji

    2003-04-01

    The combination of scanning tunneling microscopy (STM) with time-of-flight mass system (TOF-MS) adds new information to STM imaging. In this study, an STM system has been combined with laser excitation and was used for desorption and ionization of surface molecules, without the use of any other external stimulus. Desorbed ions from confined areas were accelerated and detected by a TOF chamber. We demonstrate in this paper that the technique proposed enables desorption of superficial structures within a small area of approximately 5 nm diameter and simultaneous mass spectroscopy of the desorbed atoms.

  19. Electronic Microchannel Plate Particle Detector Design for a CubeSat Time-of-Flight Reflectron Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Pyle, M. L.; Davidson, R.; Swenson, C.; Syrstad, E. A.

    2015-12-01

    Variations of gas density and composition in Earth's thermosphere and ionosphere are key indicators of interactions between different layers of Earth's atmosphere. The nature of interactions between neutral and ion species in the upper atmosphere is an active area of study in Heliophysics and there is much to learn about the dynamic relationship between the ionosphere and neutral thermosphere. Mass Spectrometers are among an array of instruments used to explore Earth's upper atmosphere and other space environments. Normally, these instruments are substantial in size and deployed on larger satellites. Data from these larger instruments generally provides information from a specific point in time at a single location. Studies of atmospheric density and composition with multiple locations for each time point could be performed by CubeSat swarms if proper instrumentation were available to fit CubeSat payload restrictions. The proposed miniaturized time-of-flight (TOF) mass spectrometer (MS) will have a mass resolution and range sufficient for measuring the composition of Earth's thermosphere and ionosphere while operating within the power and space constraints of a CubeSat. The capabilities of this instrument would potentially dramatically reduce the cost of future missions while simultaneously enhancing the science return. The design employs miniaturization of TOF-MS technology, including resolution refinement techniques used for larger instruments and standard concepts for TOF-MS components such as acceleration grids, a Bradbury-Nielsen wire gate, a gridless ion mirror, and microchannel plate detector (MCP). The quality of particle detection is known to have a significant impact on the instrument performance. A signal collector for an MCP detector is being designed to maximize the detection performance and enable the transmission of density and composition data back to Earth.

  20. A novel double-focusing time-of-flight mass spectrometer for absolute recoil ion cross sections measurements.

    PubMed

    Sigaud, L; de Jesus, V L B; Ferreira, Natalia; Montenegro, E C

    2016-08-01

    In this work, the inclusion of an Einzel-like lens inside the time-of-flight drift tube of a standard mass spectrometer coupled to a gas cell-to study ionization of atoms and molecules by electron impact-is described. Both this lens and a conical collimator are responsible for further focalization of the ions and charged molecular fragments inside the spectrometer, allowing a much better resolution at the time-of-flight spectra, leading to a separation of a single mass-to-charge unit up to 100 a.m.u. The procedure to obtain the overall absolute efficiency of the spectrometer and micro-channel plate detector is also discussed. PMID:27587105

  1. A novel double-focusing time-of-flight mass spectrometer for absolute recoil ion cross sections measurements.

    PubMed

    Sigaud, L; de Jesus, V L B; Ferreira, Natalia; Montenegro, E C

    2016-08-01

    In this work, the inclusion of an Einzel-like lens inside the time-of-flight drift tube of a standard mass spectrometer coupled to a gas cell-to study ionization of atoms and molecules by electron impact-is described. Both this lens and a conical collimator are responsible for further focalization of the ions and charged molecular fragments inside the spectrometer, allowing a much better resolution at the time-of-flight spectra, leading to a separation of a single mass-to-charge unit up to 100 a.m.u. The procedure to obtain the overall absolute efficiency of the spectrometer and micro-channel plate detector is also discussed.

  2. A novel double-focusing time-of-flight mass spectrometer for absolute recoil ion cross sections measurements

    NASA Astrophysics Data System (ADS)

    Sigaud, L.; de Jesus, V. L. B.; Ferreira, Natalia; Montenegro, E. C.

    2016-08-01

    In this work, the inclusion of an Einzel-like lens inside the time-of-flight drift tube of a standard mass spectrometer coupled to a gas cell—to study ionization of atoms and molecules by electron impact—is described. Both this lens and a conical collimator are responsible for further focalization of the ions and charged molecular fragments inside the spectrometer, allowing a much better resolution at the time-of-flight spectra, leading to a separation of a single mass-to-charge unit up to 100 a.m.u. The procedure to obtain the overall absolute efficiency of the spectrometer and micro-channel plate detector is also discussed.

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

    PubMed

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

    2016-03-01

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

  4. Molecule-Specific Imaging Analysis of Carcinogens in Breast Cancer Cells Using Time-of-Flight Secondary Ion Mass Spectrometry

    SciTech Connect

    Quong, J N; Knize, M G; Kulp, K S; Wu, K J

    2003-08-19

    Imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to study the localization of heterocyclic amines in MCF7 line of human breast cancer cells. The detection sensitivities of a model rodent mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were determined. Following an established criteria for the determination of status of freeze-fracture cells, the distribution of PhIP in the MCF7 cells are reported.

  5. Fusobacterium nucleatum subspecies identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Nie, Shuping; Tian, Baoyu; Wang, Xiaowei; Pincus, David H; Welker, Martin; Gilhuley, Kathleen; Lu, Xuedong; Han, Yiping W; Tang, Yi-Wei

    2015-04-01

    We explored the use of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of Fusobacterium nucleatum subspecies. MALDI-TOF MS spectra of five F. nucleatum subspecies (animalis, fusiforme, nucleatum, polymorphum, and vincentii) were analyzed and divided into four distinct clusters, including subsp. animalis, nucleatum, polymorphum, and fusiforme/vincentii. MALDI-TOF MS with the modified SARAMIS database further correctly identified 28 of 34 F. nucleatum clinical isolates to the subspecies level.

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

    PubMed

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

    2016-03-01

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

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

    PubMed Central

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

    2015-01-01

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

  8. Metabonomic Study of Biochemical Changes in Human Hair of Heroin Abusers by Liquid Chromatography Coupled with Ion Trap-Time of Flight Mass Spectrometry.

    PubMed

    Xie, Pu; Wang, Tie-jie; Yin, Guo; Yan, Yan; Xiao, Li-he; Li, Qing; Bi, Kai-shun

    2016-01-01

    Hair analysis is with the advantage of non-invasive collection and long surveillance window. The present study employed a sensitive and reliable liquid chromatography coupled with ion trap-time of flight mass spectrometry method to study the metabonomic characters in the hair of 58 heroin abusers and 72 non-heroin abusers. Results indicated that certain endogenous metabolites, such as sorbitol and cortisol, were accelerated, and the level of arachidonic acid, glutathione, linoleic acid, and myristic acid was decreased in hair of heroin abusers. The metabonomic study is helpful for further understanding of heroin addiction and clinical diagnosis. PMID:26445826

  9. Metabonomic Study of Biochemical Changes in Human Hair of Heroin Abusers by Liquid Chromatography Coupled with Ion Trap-Time of Flight Mass Spectrometry.

    PubMed

    Xie, Pu; Wang, Tie-jie; Yin, Guo; Yan, Yan; Xiao, Li-he; Li, Qing; Bi, Kai-shun

    2016-01-01

    Hair analysis is with the advantage of non-invasive collection and long surveillance window. The present study employed a sensitive and reliable liquid chromatography coupled with ion trap-time of flight mass spectrometry method to study the metabonomic characters in the hair of 58 heroin abusers and 72 non-heroin abusers. Results indicated that certain endogenous metabolites, such as sorbitol and cortisol, were accelerated, and the level of arachidonic acid, glutathione, linoleic acid, and myristic acid was decreased in hair of heroin abusers. The metabonomic study is helpful for further understanding of heroin addiction and clinical diagnosis.

  10. Theoretical calculations for mass resolution of a quadrupole ion trap reflectron time-of-flight mass spectrometer.

    PubMed

    Choi, Chang Min; Heo, Jiyoung; Park, Chang Joon; Kim, Nam Joon

    2010-02-01

    We have developed a theoretical method of predicting the mass resolution for a quadrupole ion trap reflectron time-of-flight (QIT-reTOF) mass spectrometer as a function of the spatial and velocity distributions of ions, voltages applied to the electrodes, and dimensions of the instrument. The flight times of ions were calculated using theoretical equations derived with an assumption of uniform electric fields inside the QIT and with the analytical description of the potential including the monopole, dipole, and quadrupole components. The mass resolution was then estimated from the flight-time spread of the ions with finite spatial and velocity distributions inside the QIT. The feasibility of the theoretical method was confirmed by the reasonable agreement of the theoretical resolution with the experimental one measured by varying the extraction voltage of the QIT or the deceleration voltage of the reflectron. We found that the theoretical resolution estimated with the assumption of the uniform electric fields inside the QIT reproduced the experimental one better than that with the analytical description of the potential. The possible applications of this theoretical method include the optimization of the experimental parameters of a given QIT-reTOF mass spectrometer and the design of new instruments with higher mass resolution.

  11. Liquid chromatography time of flight mass spectrometry based environmental metabolomics for the analysis of Pseudomonas putida Bacteria in potable water.

    PubMed

    Kouremenos, Konstantinos A; Beale, David J; Antti, Henrik; Palombo, Enzo A

    2014-09-01

    Water supply biofilms have the potential to harbour waterborne diseases, accelerate corrosion, and contribute to the formation of tuberculation in metallic pipes. One particular species of bacteria known to be found in the water supply networks is Pseudomonas sp., with the presence of Pseudomonas putida being isolated to iron pipe tubercles. Current methods for detecting and analysis pipe biofilms are time consuming and expensive. The application of metabolomics techniques could provide an alternative method for assessing biofilm risk more efficiently based on bacterial activity. As such, this paper investigates the application of metabolomic techniques and provides a proof-of-concept application using liquid chromatography coupled with time-of-flight mass spectrometry (LC-ToF-MS) to three biologically independent P. putida samples, across five different growth conditions exposed to solid and soluble iron (Fe). Analysis of the samples in +ESI and -ESI mode yielded 887 and 1789 metabolite features, respectively. Chemometric analysis of the +ESI and -ESI data identified 34 and 39 significant metabolite features, respectively, where features were considered significant if the fold change was greater than 2 and obtained a p-value less than 0.05. Metabolite features were subsequently identified according to the Metabolomics Standard Initiative (MSI) Chemical Analysis Workgroup using analytical standards and standard online LC-MS databases. Possible markers for P. putida growth, with and without being exposed to solid and soluble Fe, were identified from a diverse range of different chemical classes of metabolites including nucleobases, nucleosides, dipeptides, tripeptides, amino acids, fatty acids, sugars, and phospholipids.

  12. A quadrupole/time-of-flight mass spectrometry study of Trp-cage's conformation.

    PubMed

    Lin, Mingxiang; Ahmed, Zeeshan; Taormina, Christopher R; Somayajula, Kasi V

    2007-02-01

    Trp-cage is a synthetic 20-residue miniprotein that uses tertiary contacts to stabilize its native conformation. NMR, circular dichroism (CD), and UV-resonance Raman spectroscopy were used to probe its energy landscape. In this quadrupole/time-of-flight study, electrospray ionization charge state distribution (CSD) and solution-phase H/D exchange are used to probe Trp-cage's tertiary structure. The CSDs of Trp-cage and its mutant provide spectra showing a pH-dependent conformation change. Solution-phase H/D exchange in 30% deuterated trifluoroethanol solution of the wild type shows increased protection of one labile hydrogen in the native state. Together, CSDs and solution-phase H/D exchange are demonstrated to constitute a simple but effective means to follow conformation changes in a small tertiary protein. PMID:17067814

  13. Time of flight mass spectra of ions in plasmas produced by hypervelocity impacts of organic and mineralogical microparticles on a cosmic dust analyser

    NASA Astrophysics Data System (ADS)

    Goldsworthy, B. J.; Burchell, M. J.; Cole, M. J.; Armes, S. P.; Khan, M. A.; Lascelles, S. F.; Green, S. F.; McDonnell, J. A. M.; Srama, R.; Bigger, S. W.

    2003-10-01

    The ionic plasma produced by a hypervelocity particle impact can be analysed to determine compositional information for the original particle by using a time-of-flight mass spectrometer. Such methods have been adopted on interplanetary dust detectors to perform in-situ analyses of encountered grains, for example, the Cassini Cosmic Dust Analyser (CDA). In order to more fully understand the data returned by such instruments, it is necessary to study their response to impacts in the laboratory. Accordingly, data are shown here for the mass spectra of ionic plasmas, produced through the acceleration of microparticles via a 2 MV van de Graaff accelerator and their impact on a dimensionally correct CDA model with a rhodium target. The microparticle dusts examined have three different chemical compositions: metal (iron), organic (polypyrrole and polystyrene latex) and mineral (aluminosilicate clay). These microparticles have mean diameters in the range 0.1 to 1.6 mu m and their velocities range from 1-50 km s-1. They thus cover a wide range of compositions, sizes and speeds expected for dust particles encountered by spacecraft in the Solar System. The advent of new low-density, microparticles with highly controllable attributes (composition, size) has enabled a number of new investigations in this area. The key is the use of a conducting polymer, either as the particle itself or as a thin overlayer on organic (or inorganic) core particles. This conductive coating permits efficient electrostatic charging and acceleration. Here, we examine how the projectile's chemical composition influences the ionic plasma produced after the hypervelocity impact. This study thus extends our understanding of impact plasma formation and detection. The ionization yield normalized to particle mass was found to depend on impact speed to the power (3.4 +/- 0.1) for iron and (2.9 +/- 0.1) for polypyrrole coated polystyrene and aluminosilicate clay. The ioization signal rise time was found to

  14. Two-step Laser Time-of-Flight Mass Spectrometry to Elucidate Organic Diversity in Planetary Surface Materials.

    NASA Technical Reports Server (NTRS)

    Getty, Stephanie A.; Brinckerhoff, William B.; Cornish, Timothy; Li, Xiang; Floyd, Melissa; Arevalo, Ricardo Jr.; Cook, Jamie Elsila; Callahan, Michael P.

    2013-01-01

    Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) holds promise to be a low-mass, compact in situ analytical capability for future landed missions to planetary surfaces. The ability to analyze a solid sample for both mineralogical and preserved organic content with laser ionization could be compelling as part of a scientific mission pay-load that must be prepared for unanticipated discoveries. Targeted missions for this instrument capability include Mars, Europa, Enceladus, and small icy bodies, such as asteroids and comets.

  15. Large scale pesticide multiresidue methods in food combining liquid chromatography--time-of-flight mass spectrometry and tandem mass spectrometry.

    PubMed

    García-Reyes, Juan F; Hernando, M Dolores; Ferrer, Carmen; Molina-Díaz, Antonio; Fernández-Alba, Amadeo R

    2007-10-01

    Liquid chromatography tandem mass spectrometry (LC-MS/MS) and liquid chromatography time-of-flight mass spectrometry (LC-TOFMS) are powerful and complementary techniques that can independently cover the majority of the challenges related with pesticide residue food control. The sequential combination of both systems benefits from their complementary advantages and assists to increase the performance and to simplify routine large scale pesticide multiresidue methods. The proposed approach consists of three stages: (1) automated pesticide screening by LC-TOFMS; (2) identification by LC-TOFMS accurate mass measurements; and (3) confirmation and quantitation by LC-MS/MS. We have developed a fast comprehensive (identification/confirmation + quantitation) automated screening method for 100 target pesticides in crops. In the first stage, a set of data including m/z accurate mass windows (within 20 mDa width) and retention time is obtained (using a standard solution containing all the targeted pesticides) in order to build the automated screening procedure, which is created automatically by assigning retention time and the m/z mass window for each target pesticide. Samples are then analyzed, and the method enables the screening and preliminary identification of the species first by retention time and m/z mass window, followed by subsequent identification (only if positive results) by LC-TOFMS accurate mass measurements. After that, final confirmation of the positive findings using two MRM transitions and accurate quantitation is performed by LC-MS/MS using a hybrid triple quadrupole linear ion trap (QqLIT) mass spectrometer. In addition, the use of this QqLIT instrument also offers additional advantageous scanning modes (enhanced product ion and MS3 modes) for confirmatory purposes in compounds with poor fragmentation. Examples of applications to real samples show the potential of the proposed approach, including the detection of nonselected "a priori" compounds as a

  16. PILGRIM, a Multi-Reflection Time-of-Flight Mass Spectrometer for Spiral2-S3 at GANIL

    NASA Astrophysics Data System (ADS)

    Chauveau, P.; Delahaye, P.; De France, G.; El Abir, S.; Lory, J.; Merrer, Y.; Rosenbusch, M.; Schweikhard, L.; Wolf, R. N.

    2016-06-01

    PILGRIM is a Multi-Reflection Time-of-Flight Mass Spectrometer currently under development at GANIL for the S3 (Super Separator Spectrometer) collaboration and dedicated to the study of the ground-state properties of exotic nuclei. MR-ToF devices have proven to be effective tools for isobar separation (with mass resolving powers in excess of 105) and high-precision mass measurements (relative mass uncertainty down to a few 10-7) within a few tens of milliseconds. These features make them extremely interesting for ensuring beam purity and accurate mass determinations of very exotic, short lived nuclei. PILGRIM is to be set up in the future low energy branch of the S3-Spiral2 project and may also be used as a beam purifier in front of the double Penning trap PIPERADE at DESIR-Spiral2. An electrostatic 90 degree quadrupole deflector to be placed between an RFQ cooler-buncher (for beam preparation) and PILGRIM is also under study. The study on the deflector focuses on conserving the beam features, especially the time-of-flight spread of the ion bunches which has a direct impact on the resolving power of a multi-reflection device.

  17. Shock tube coupled to the time-of-flight mass spectrometer via a molecular beam sampling system.

    PubMed

    Krizancic, I; Haluk, M; Cho, S H; Trass, O

    1979-07-01

    A method for continuous mass spectrometric analysis of high-temperature reacting gas mixtures is described. The apparatus consists of a unique combination of three devices: the shock tube, the time-of-flight mass spectrometer, and the supersonic molecular beam. The driven section of the shock tube constitutes the reservoir of a supersonic molecular beam by which gas is continuously extracted from the reaction zone and introduced through a two-stage high-capacity vacuum system into the ionization region of the mass spectrometer. The shock tube and the mass spectrometer are coupled at right angles to one another. This configuration avoids excessive pressure buildup in the mass spectrometer system. The apparatus has an estimated mass resolution of 100 amu, a frequency range of 10-100 kHz, and can be operated over a wide range of shock conditions during the complete high-temperature pulse. PMID:18699630

  18. Time-of-flight secondary ion mass spectrometry with transmission of energetic primary cluster ions through foil targets

    SciTech Connect

    Hirata, K.; Saitoh, Y.; Chiba, A.; Yamada, K.; Matoba, S.; Narumi, K.

    2014-03-15

    We developed time-of-flight (TOF) secondary ion (SI) mass spectrometry that provides informative SI ion mass spectra without needing a sophisticated ion beam pulsing system. In the newly developed spectrometry, energetic large cluster ions with energies of the order of sub MeV or greater are used as primary ions. Because their impacts on the target surface produce high yields of SIs, the resulting SI mass spectra are informative. In addition, the start signals necessary for timing information on primary ion incidence are provided by the detection signals of particles emitted from the rear surface of foil targets upon transmission of the primary ions. This configuration allows us to obtain positive and negative TOF SI mass spectra without pulsing system, which requires precise control of the primary ions to give the spectra with good mass resolution. We also successfully applied the TOF SI mass spectrometry with energetic cluster ion impacts to the chemical structure characterization of organic thin film targets.

  19. Time-of-flight secondary ion mass spectrometry with transmission of energetic primary cluster ions through foil targets.

    PubMed

    Hirata, K; Saitoh, Y; Chiba, A; Yamada, K; Matoba, S; Narumi, K

    2014-03-01

    We developed time-of-flight (TOF) secondary ion (SI) mass spectrometry that provides informative SI ion mass spectra without needing a sophisticated ion beam pulsing system. In the newly developed spectrometry, energetic large cluster ions with energies of the order of sub MeV or greater are used as primary ions. Because their impacts on the target surface produce high yields of SIs, the resulting SI mass spectra are informative. In addition, the start signals necessary for timing information on primary ion incidence are provided by the detection signals of particles emitted from the rear surface of foil targets upon transmission of the primary ions. This configuration allows us to obtain positive and negative TOF SI mass spectra without pulsing system, which requires precise control of the primary ions to give the spectra with good mass resolution. We also successfully applied the TOF SI mass spectrometry with energetic cluster ion impacts to the chemical structure characterization of organic thin film targets.

  20. Mycobacterium abscessus Complex Identification with Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Panagea, Theofano; Pincus, David H.; Grogono, Dorothy; Jones, Melissa; Bryant, Josephine; Parkhill, Julian; Floto, R. Andres

    2015-01-01

    We determined that the Vitek MS Plus matrix-assisted laser desorption ionization–time of flight mass spectrometry using research-use-only (RUO) v.4.12 and in vitro-diagnostic (IVD) v.3.0 databases accurately identified 41 Mycobacterium abscessus subsp. abscessus and 13 M. abscessus subsp. massiliense isolates identified by whole-genome sequencing to the species but not the subspecies level, from Middlebrook 7H11 and Burkholderia cepacia selective agars. Peak analysis revealed three peaks potentially able to differentiate between subspecies. PMID:25948607

  1. Mycobacterium abscessus Complex Identification with Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Panagea, Theofano; Pincus, David H; Grogono, Dorothy; Jones, Melissa; Bryant, Josephine; Parkhill, Julian; Floto, R Andres; Gilligan, Peter

    2015-07-01

    We determined that the Vitek MS Plus matrix-assisted laser desorption ionization-time of flight mass spectrometry using research-use-only (RUO) v.4.12 and in vitro-diagnostic (IVD) v.3.0 databases accurately identified 41 Mycobacterium abscessus subsp. abscessus and 13 M. abscessus subsp. massiliense isolates identified by whole-genome sequencing to the species but not the subspecies level, from Middlebrook 7H11 and Burkholderia cepacia selective agars. Peak analysis revealed three peaks potentially able to differentiate between subspecies. PMID:25948607

  2. Mass determination of light ions in a Penning trap by time-of-flight detection of ion resonances

    NASA Astrophysics Data System (ADS)

    Kern, J.; Engel, T.; Hagena, D.; Werth, G.

    1992-12-01

    We describe an experimental setup to determine the cyclotron frequencies of ions confined in a Penning trap by resonant excitation of the ions eigenfrequencies and a time-of-flight detection of the resonances. Systematic shifts from trap- and B-field imperfections are discussed and methods to minimize those effects in our experiment are presented. Results on the mass ratio for 4He/D2 and 3He/H2 demonstrate the experimentally obtained precision in the ppb range, which might be further improved by modification of our apparatus.

  3. Monitoring single coffee bean roasting by direct volatile compound analysis with proton transfer reaction time-of-flight mass spectrometry.

    PubMed

    Yener, Sine; Navarini, Luciano; Lonzarich, Valentina; Cappellin, Luca; Märk, Tilmann D; Bonn, Günther K; Biasioli, Franco

    2016-09-01

    This study applies proton transfer reaction time-of-flight mass spectrometry for the rapid analysis of volatile compounds released from single coffee beans. The headspace volatile profiles of single coffee beans (Coffeea arabica) from different geographical origins (Brazil, Guatemala and Ethiopia) were analyzed via offline profiling at different stages of roasting. The effect of coffee geographical origin was reflected on volatile compound formation that was supported by one-way ANOVA. Clear origin signatures were observed in the formation of different coffee odorants. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27476633

  4. Current status of matrix-assisted laser desorption ionisation-time of flight mass spectrometry in the clinical microbiology laboratory.

    PubMed

    Kok, Jen; Chen, Sharon C A; Dwyer, Dominic E; Iredell, Jonathan R

    2013-01-01

    The integration of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) into many clinical microbiology laboratories has revolutionised routine pathogen identification. MALDI-TOF MS complements and has good potential to replace existing phenotypic identification methods. Results are available in a more clinically relevant timeframe, particularly in bacteraemic septic shock. Novel applications include strain typing and the detection of antimicrobial resistance, but these are not widely used. This review discusses the technical aspects, current applications, and limitations of MALDI-TOF MS.

  5. Direct Mass Measurements in the Light Neutron-Rich Region Using a Combined Energy and Time-of-Flight Technique

    NASA Astrophysics Data System (ADS)

    Pillai, C.; Swenson, L. W.; Vieira, D. J.; Butler, G. W.; Wouters, J. M.; Rokni, S. H.; Vaziri, K.; Remsberg, L. P.

    This experiment has demonstrated that direct mass measurements can be performed (albeit of low precision in this first attempt) using the M proportional to ET(2) method. This technique has the advantage that many particle-bound nuclei, produced in fragmentation reactions can be measured simultaneously, independent of their N or Z. The main disadvantage of this approach is that both energy and time-of-flight must be measured precisely on an absolute scale. Although some mass walk with N and Z was observed in this experiment, these uncertainties were largely removed by extrapolating the smooth dependence observed for known nuclei which lie closer to the valley of (BETA)-stability. Mass measurements for several neutron-rich light nuclei ranging from C-17 to NE-26 have been performed. In all cases these measurements agree with the latest mass compilation of Wapstra and Audi. The masses of N-20 N and F-24 have been determined for the first time.

  6. Potential of monitoring isotopologues by quantitative gas chromatography with time-of-flight mass spectrometry for metabolomic assay.

    PubMed

    Wang, Yi; Hu, Haiyan; Su, Yue; Zhang, Fang; Guo, Yinlong

    2016-03-01

    Because of the extreme complexity of metabolomic samples, the effectiveness of quantitative gas chromatography with time-of-flight mass spectrometry depends substantially on the expansion of the linear dynamic range. Facing the existence of numerous saturated detector signals, a data processing method based on monitoring isotopologues has been developed. The monoisotopic ion kept the high mass spectrometry sensitivity, and the less abundant isotopologue ions extended the linear dynamic range. This alternative method was proved to extend the linear dynamic range to five orders of magnitude successfully and overcome the quantitative problems induced by the ion detector saturation. Finally, to validate the applicability, the method was applied to a metabolomic assay of Alzheimer's disease. Comparing with the traditional monoisotopic method, the use of monitoring isotopologues helped us to discover an additional eight metabolites with significant difference and to conduct a more reliable principal component analysis as well. The results demonstrated that monitoring isotopologues in quantitative gas chromatography with time-of-flight mass spectrometry could improve the authenticity of metabolomic analysis. PMID:26763370

  7. Quantitative Organic Acids in Urine by Two Dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS).

    PubMed

    Sweetman, Lawrence; Ashcraft, Paula; Bennett-Firmin, Jeanna

    2016-01-01

    Seventy-six organic acids in urine specimens are determined with quantitative two dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS). The specimen is treated with urease to remove urea then derivatized to form pentafluorobenzyl oximes (PFBO) of oxoacids. The sample is then treated with ethyl alcohol to precipitate proteins and centrifuged. After drying the supernatant, the organic acids are derivatized to form volatile trimethylsilyl (TMS) derivatives for separation by capillary two dimensional Gas Chromatography (GCxGC) with temperature programming and modulation. Detection is by Time of Flight Mass Spectrometry (TOFMS) with identification of the organic acids by their mass spectra. Organic acids are quantitated by peak areas of reconstructed ion chromatograms with internal standards and calibration curves. Organic acids are quantified to determine abnormal patterns for the diagnosis of more than 100 inherited disorders of organic acid metabolism. Characteristic abnormal metabolites are quantified to monitor dietary and other modes of treatment for patients who are diagnosed with specific organic acid disorders.

  8. Clustering, methodology, and mechanistic insights into acetate chemical ionization using high-resolution time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Brophy, Patrick; Farmer, Delphine K.

    2016-08-01

    We present a comprehensive characterization of cluster control and transmission through the Tofwerk atmospheric pressure interface installed on various chemical ionization time-of-flight mass spectrometers using authentic standards. This characterization of the atmospheric pressure interface allows for a detailed investigation of the acetate chemical ionization mechanisms and the impact of controlling these mechanisms on sensitivity, selectivity, and mass spectral ambiguity with the aim of non-targeted analysis. Chemical ionization with acetate reagent ions is controlled by a distribution of reagent ion-neutral clusters that vary with relative humidity and the concentration of the acetic anhydride precursor. Deprotonated carboxylic acids are primarily detected only if sufficient declustering is employed inside the atmospheric pressure interface. The configuration of a high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) using an acetate chemical ionization source for non-targeted analysis is discussed. Recent approaches and studies characterizing acetate chemical ionization as it applies to the HR-TOF-CIMS are evaluated in light of the work presented herein.

  9. Analysis of sucralose and other sweeteners in water and beverage samples by liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    Ferrer, Imma; Thurman, E Michael

    2010-06-18

    A methodology for the chromatographic separation and analysis of three of the most popular artificial sweeteners (aspartame, saccharin, and sucralose) in water and beverage samples was developed using liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS). The sweeteners were extracted from water samples using solid-phase extraction (SPE) cartridges. Furthermore, several beverages were analyzed by a rapid and simple method without SPE, and the presence of the sweeteners was confirmed by accurate mass measurements below 2-ppm error. The unambiguous confirmation of the compounds was based on accurate mass measurements of the protonated molecules [M+H](+), their sodium adducts and their main fragment ions. Quantitation was carried out using matrix-matched standard calibration and linearity of response over 2 orders of magnitude was demonstrated (r>0.99). A detailed fragmentation study for sucralose was carried out by time-of-flight and a characteristic spectrum fingerprint pattern was obtained for the presence of this compound in water samples. Finally, the analysis of several wastewater, surface water and groundwater samples from the US showed that sucralose can be found in the aquatic environment at concentrations up to 2.4microg/L, thus providing a good indication of wastewater input from beverage sources.

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

    PubMed Central

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

    2006-01-01

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

  11. Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer

    SciTech Connect

    Westmacott, G.; Zhong, F.; Frank, M.; Friedrich, S.; Labov, S.; Benner, W.H.

    1999-12-01

    The performance of an energy sensitive, niobium superconducting tunnel junction detector is investigated by measuring the pulse height produced by impacting molecular and atomic ions at different kinetic energies. Ions are produced by laser resorption and matrix-assisted laser desorption in a time-of-flight mass spectrometer. Results show that the STJ detector pulse height decreases for increasing molecular ion mass, passes through a minimum at around 2000 Da, and the increases with increasing mass of molecular ions above 2000Da. The detector does not show a decline in sensitivity for high mass ions as is observed with microchannel plate ion detectors. These detector plus height measurements are discussed in terms of several physical mechanisms involved in an ion-surface collision.

  12. An integrated ion trap and time-of-flight mass spectrometer for chemical and photo- reaction dynamics studies.

    PubMed

    Schowalter, Steven J; Chen, Kuang; Rellergert, Wade G; Sullivan, Scott T; Hudson, Eric R

    2012-04-01

    We demonstrate the integration of a linear quadrupole trap with a simple time-of-flight mass spectrometer with medium-mass resolution (m/Δm ∼ 50) geared towards the demands of atomic, molecular, and chemical physics experiments. By utilizing a novel radial ion extraction scheme from the linear quadrupole trap into the mass analyzer, a device with large trap capacity and high optical access is realized without sacrificing mass resolution. This provides the ability to address trapped ions with laser light and facilitates interactions with neutral background gases prior to analyzing the trapped ions. Here, we describe the construction and implementation of the device as well as present representative ToF spectra. We conclude by demonstrating the flexibility of the device with proof-of-principle experiments that include the observation of molecular-ion photodissociation and the measurement of trapped-ion chemical reaction rates.

  13. A Rocket-Borne Axially Sampling Time-of-Flight Mass Spectrometer for Investigation of the Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Everett, E. A.; Syrstad, E. A.

    2013-12-01

    We have previously reported results from modeling and simulation efforts and preliminary laboratory testing for a new rocket-borne time-of-flight mass spectrometer (TOF-MS) for direct, in-situ measurements in the mesosphere/lower thermosphere (MLT) region of Earth's atmosphere. Mass spectrometry in the MLT is difficult, mainly due to the high ambient pressures in the MLT and also the high speeds and short flight durations of sounding rocket missions. In particular, TOF-MS has rarely been applied to the MLT, owing to the dependence of this MS technique on high acceleration voltages and microchannel plate (MCP) detectors. To overcome these obstacles, the TOF-MS relies on a pressure tolerant MCP as well as modest acceleration potentials (100 V - 300 V). The TOF-MS is adaptable and vacuum requirements can be met by several options, including an innovative design using an inexpensive barium getter tube system, mechanical pumping system, or a cryogenic pumping system. This presentation highlights results from laboratory testing of a prototype TOF-MS instrument, demonstrating the ability of the TOF-MS to survive and operate in the challenging MLT region. MCP's have traditionally required vacuum conditions of 10-6 torr or better for operation. We have rigorously tested the effects of pressure on the MCP detector used in the TOF-MS under backfills of gases including He, Ar, N2, and lab air, at pressures extending into the 10-2 torr range. We have also tested the effect of humidity on MCP performance. Discharge events were also tracked. These experiments demonstrate the ability of the MCP detector to perform under the high pressure conditions likely to be encountered on a sounding rocket in the MLT. Additionally, optimal operating parameters for the laboratory prototype TOF-MS have been experimentally determined and applied to study the effects of pressure on the resolution and SNR of mass spectra taken with the TOF-MS. The TOF-MS has successfully operated with internal

  14. Critical factors determining the quantification capability of matrix-assisted laser desorption/ionization- time-of-flight mass spectrometry.

    PubMed

    Wang, Chia-Chen; Lai, Yin-Hung; Ou, Yu-Meng; Chang, Huan-Tsung; Wang, Yi-Sheng

    2016-10-28

    Quantitative analysis with mass spectrometry (MS) is important but challenging. Matrix-assisted laser desorption/ionization (MALDI) coupled with time-of-flight (TOF) MS offers superior sensitivity, resolution and speed, but such techniques have numerous disadvantages that hinder quantitative analyses. This review summarizes essential obstacles to analyte quantification with MALDI-TOF MS, including the complex ionization mechanism of MALDI, sensitive characteristics of the applied electric fields and the mass-dependent detection efficiency of ion detectors. General quantitative ionization and desorption interpretations of ion production are described. Important instrument parameters and available methods of MALDI-TOF MS used for quantitative analysis are also reviewed.This article is part of the themed issue 'Quantitative mass spectrometry'.

  15. Time of flight mass spectrometry of DNA laser-ablated from frozen aqueous solutions: applications to the Human Genome Project

    NASA Astrophysics Data System (ADS)

    Williams, Peter

    1994-02-01

    Time of flight mass spectrometry offers an extremely rapid and accurate alternative to gel electrophoresis for sizing DNA fragments in the Sanger sequencing process, if large single-stranded DNA molecules can be volatilized and ionized without fragmentation. A process based on pulsed laser ablation of thin frozen films of DNA solutions has been shown to ablate intact DNA molecules up to [approximate]400 kDa in mass, and also has been shown to yield molecular ions of single-stranded DNA up to [approximate]18 500 Da. The theoretical basis and the progress to date in this approach are described and the potential impact of mass spectrometry on large-scale DNA sequencing is discussed.

  16. Critical factors determining the quantification capability of matrix-assisted laser desorption/ionization- time-of-flight mass spectrometry.

    PubMed

    Wang, Chia-Chen; Lai, Yin-Hung; Ou, Yu-Meng; Chang, Huan-Tsung; Wang, Yi-Sheng

    2016-10-28

    Quantitative analysis with mass spectrometry (MS) is important but challenging. Matrix-assisted laser desorption/ionization (MALDI) coupled with time-of-flight (TOF) MS offers superior sensitivity, resolution and speed, but such techniques have numerous disadvantages that hinder quantitative analyses. This review summarizes essential obstacles to analyte quantification with MALDI-TOF MS, including the complex ionization mechanism of MALDI, sensitive characteristics of the applied electric fields and the mass-dependent detection efficiency of ion detectors. General quantitative ionization and desorption interpretations of ion production are described. Important instrument parameters and available methods of MALDI-TOF MS used for quantitative analysis are also reviewed.This article is part of the themed issue 'Quantitative mass spectrometry'. PMID:27644968

  17. CHARACTERIZATION OF CRYPTOSPORIDIUM PARVUM BY MATRIX-ASSISTED LASER DESORPTION -- IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    Matrix assisted laser desorption/ionization (MALDI) mass spectrometry was used to investigate whole and freeze thawed Cryptosporidium parvum oocysts. Whole oocysts revealed some mass spectral features. Reproducible patterns of spectral markers and increased sensitivity were obtai...

  18. Screening for basic drugs in hair of drug addicts by liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    Pelander, Anna; Ristimaa, Johanna; Rasanen, Ilpo; Vuori, Erkki; Ojanperä, Ilkka

    2008-12-01

    Hair analysis in forensic and clinical toxicology has been strongly focused on drugs of abuse, and comprehensive, drug class-independent screening methods based on mass spectrometric detection have not been applied to date. In this study, a qualitative drug screening method by liquid chromatography coupled to time-of-flight mass spectrometry, earlier developed and evaluated for forensic toxicological urine analysis, was adapted for screening of basic drugs in hair. The method included alkaline hydrolysis, purification with mixed-mode solid phase extraction, and analysis by liquid chromatography coupled to time-of-flight mass spectrometry with automated data analysis and reporting. Identification was based on accurate mass, isotopic pattern fit, and retention time, if available. Analysis of 32 hair samples from deceased drug addicts revealed 35 different drugs. The drug classes identified included antidepressants, antipsychotics, antiepileptics, amphetamines, opioids, beta-blockers, a benzodiazepine, a hypnotic, a local anesthetic, an antiemetic, and an antipyretic analgesic. The findings were in good agreement with the findings in blood and urine by other methods. Moreover, information about previous drug use not evident in the analysis of other matrices was obtained in the majority (72%) of the cases. Tramadol was an especially predominant finding, suggesting tramadol abuse as an opioid substitute. One apparent false-positive finding was identified. The mean and median mass accuracies of positive findings were 2.3 and 1.8 ppm, corresponding to 0.5 and 0.4 mDa, respectively. Cutoff values for tramadol and methamphetamine in hair were 100 and 200 pg/mg, respectively. The method proved to be a simple and straightforward tool for comprehensive screening of basic drugs in hair.

  19. Enhancing gas chromatography-time of flight mass spectrometry data analysis using two-dimensional mass channel cluster plots.

    PubMed

    Fitz, Brian D; Reaser, Brooke C; Pinkerton, David K; Hoggard, Jamin C; Skogerboe, Kristen J; Synovec, Robert E

    2014-04-15

    A novel data reduction and representation method for gas chromatography time-of-flight mass spectrometry (GC-TOFMS) is presented that significantly facilitates separation visualization and analyte peak deconvolution. The method utilizes the rapid mass spectral data collection rate (100 scans/s or greater) of current generation TOFMS detectors. Chromatographic peak maxima (serving as the retention time, tR) above a user specified signal threshold are located, and the chromatographic peak width, W, are determined on a per mass channel (m/z) basis for each analyte peak. The peak W (per m/z) is then plotted against its respective tR (with 10 ms precision) in a two-dimensional (2D) format, producing a cluster of points (i.e., one point per peak W versus tR in the 2D plot). Analysis of GC-TOFMS data by this method produces what is referred to as a two-dimensional mass channel cluster plot (2D m/z cluster plot). We observed that adjacent eluting (even coeluting) peaks in a temperature programmed separation can have their peak W vary as much as ∼10-15%. Hence, the peak W provides useful chemical selectivity when viewed in the 2D m/z cluster plot format. Pairs of overlapped analyte peaks with one-dimensional GC resolution as low as Rs ≈ 0.03 can be visually identified as fully resolved in a 2D m/z cluster plot and readily deconvoluted using chemometrics (i.e., demonstrated using classical least-squares analysis). Using the 2D m/z cluster plot method, the effective peak capacity of one-dimensional GC separations is magnified nearly 40-fold in one-dimensional GC, and potentially ∼100-fold in the context of comparing it to a two-dimensional separation. The method was studied using a 73 component test mixture separated on a 30 m × 250 μm i.d. RTX-5 column with a LECO Pegasus III TOFMS.

  20. Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry

    PubMed Central

    Park, Jonghoo; Blick, Robert H.

    2016-01-01

    We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. PMID:26861329

  1. Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry.

    PubMed

    Park, Jonghoo; Blick, Robert H

    2016-01-01

    We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. PMID:26861329

  2. Polychlorinated biphenyls (PCBs) analysis using a miniaturized high-resolution time-of-flight mass spectrometer "MULTUM-S II".

    PubMed

    Shimma, Shuichi; Miki, Shinichi; Toyoda, Michisato

    2012-05-01

    In this study, we conducted polychlorinated biphenyls (PCBs) analysis using fast gas chromatography (GC)/high-resolution mass spectrometry (HRMS). Mass spectrometry (MS) was performed with a miniature multi-turn time-of-flight (TOF) analyzer called "MULTUM-S II". MULTUM-S II is truly a portable high resolution mass spectrometer. The mass spectrometer's high resolution capability is due to its theoretical infinite flight path utilizing perfect space and time focusing within a closed flight orbit. Mass resolution above 10 000 was easily achievable employing this portable system. This mass resolution is comparable to magnetic sector mass spectrometers, which have traditionally performed PCB analyses in the past. At a resolution of 10 000, a limit-of-detection of 1 ppb was determined using a heptachlorinated biphenyl standard sample. Using this fast GC/HRMS, 66 PCB congeners were analyzed within 5 min. In addition experiments aimed at confirming interference of PCB signal peaks and matrix peaks in diluted dielectric coolant fluids were performed. We found that the PCB signal peaks were detected without matrix interference via high mass resolution.

  3. Exploring the phase space of time of flight mass selected Pt(x)Y nanoparticles.

    PubMed

    Masini, Federico; Hernández-Fernández, Patricia; Deiana, Davide; Strebel, Christian Ejersbo; McCarthy, David Norman; Bodin, Anders; Malacrida, Paolo; Stephens, Ifan; Chorkendorff, Ib

    2014-12-28

    Mass-selected nanoparticles can be conveniently produced using magnetron sputtering and aggregation techniques. However, numerous pitfalls can compromise the quality of the samples, e.g. double or triple mass production, dendritic structure formation or unpredicted particle composition. We stress the importance of transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS) for verifying the morphology, size distribution and chemical composition of the nanoparticles. Furthermore, we correlate the morphology and the composition of the PtxY nanoparticles with their catalytic properties for the oxygen reduction reaction. Finally, we propose a completely general diagnostic method, which allows us to minimize the occurrence of undesired masses.

  4. Electrospray ionization time-of-flight mass spectrum analysis method of polyaluminum chloride flocculants.

    PubMed

    Feng, Chenghong; Bi, Zhe; Tang, Hongxiao

    2015-01-01

    Electrospray mass spectrometry has been reported as a novel technique for Al species identification, but to date, the working mechanism is not clear and no unanimous method exists for spectrum analysis of traditional Al salt flocculants, let alone for analysis of polyaluminum chloride (PAC) flocculants. Therefore, this paper introduces a novel theoretical calculation method to identify Al species from a mass spectrum, based on deducing changes in m/z (mass-to-charge ratio) and molecular formulas of oligomers in five typical PAC flocculants. The use of reference chemical species was specially proposed in the method to guarantee the uniqueness of the assigned species. The charge and mass reduction of the Al cluster was found to proceed by hydrolysis, gasification, and change of hydroxyl on the oxy bridge. The novel method was validated both qualitatively and quantitatively by comparing the results to those obtained with the (27)Al NMR spectrometry.

  5. Accelerated time-of-flight (TOF) PET image reconstruction using TOF bin subsetization and TOF weighting matrix pre-computation

    NASA Astrophysics Data System (ADS)

    Mehranian, Abolfazl; Kotasidis, Fotis; Zaidi, Habib

    2016-02-01

    Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, thereby the cross-dependencies of image voxels are reduced, which in turns results in improved signal-to-noise ratio and convergence rate. In this work, we propose a novel approach to further improve the convergence of the expectation maximization (EM)-based TOF PET image reconstruction algorithm through subsetization of emission data over TOF bins as well as azimuthal bins. Given the prevalence of TOF PET, we elaborated the practical and efficient implementation of TOF PET image reconstruction through the pre-computation of TOF weighting coefficients while exploiting the same in-plane and axial symmetries used in pre-computation of geometric system matrix. In the proposed subsetization approach, TOF PET data were partitioned into a number of interleaved TOF subsets, with the aim of reducing the spatial coupling of TOF bins and therefore to improve the convergence of the standard maximum likelihood expectation maximization (MLEM) and ordered subsets EM (OSEM) algorithms. The comparison of on-the-fly and pre-computed TOF projections showed that the pre-computation of the TOF weighting coefficients can considerably reduce the computation time of TOF PET image reconstruction. The convergence rate and bias-variance performance of the proposed TOF subsetization scheme were evaluated using simulated, experimental phantom and clinical studies. Simulations demonstrated that as the number of TOF subsets is increased, the convergence rate of MLEM and OSEM algorithms is improved. It was also found that for the same computation time, the proposed subsetization gives rise to further convergence. The bias-variance analysis of the experimental NEMA phantom and a clinical

  6. Accelerated time-of-flight (TOF) PET image reconstruction using TOF bin subsetization and TOF weighting matrix pre-computation.

    PubMed

    Mehranian, Abolfazl; Kotasidis, Fotis; Zaidi, Habib

    2016-02-01

    Time-of-flight (TOF) positron emission tomography (PET) technology has recently regained popularity in clinical PET studies for improving image quality and lesion detectability. Using TOF information, the spatial location of annihilation events is confined to a number of image voxels along each line of response, thereby the cross-dependencies of image voxels are reduced, which in turns results in improved signal-to-noise ratio and convergence rate. In this work, we propose a novel approach to further improve the convergence of the expectation maximization (EM)-based TOF PET image reconstruction algorithm through subsetization of emission data over TOF bins as well as azimuthal bins. Given the prevalence of TOF PET, we elaborated the practical and efficient implementation of TOF PET image reconstruction through the pre-computation of TOF weighting coefficients while exploiting the same in-plane and axial symmetries used in pre-computation of geometric system matrix. In the proposed subsetization approach, TOF PET data were partitioned into a number of interleaved TOF subsets, with the aim of reducing the spatial coupling of TOF bins and therefore to improve the convergence of the standard maximum likelihood expectation maximization (MLEM) and ordered subsets EM (OSEM) algorithms. The comparison of on-the-fly and pre-computed TOF projections showed that the pre-computation of the TOF weighting coefficients can considerably reduce the computation time of TOF PET image reconstruction. The convergence rate and bias-variance performance of the proposed TOF subsetization scheme were evaluated using simulated, experimental phantom and clinical studies. Simulations demonstrated that as the number of TOF subsets is increased, the convergence rate of MLEM and OSEM algorithms is improved. It was also found that for the same computation time, the proposed subsetization gives rise to further convergence. The bias-variance analysis of the experimental NEMA phantom and a clinical

  7. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.

    PubMed

    Marin, Stephanie J; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A; Johnson-Davis, Kamisha L

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs. PMID:26342055

  8. One Hundred False-Positive Amphetamine Specimens Characterized by Liquid Chromatography Time-of-Flight Mass Spectrometry.

    PubMed

    Marin, Stephanie J; Doyle, Kelly; Chang, Annie; Concheiro-Guisan, Marta; Huestis, Marilyn A; Johnson-Davis, Kamisha L

    2016-01-01

    Some amphetamine (AMP) and ecstacy (MDMA) urine immunoassay (IA) kits are prone to false-positive results due to poor specificity of the antibody. We employed two techniques, high-resolution mass spectrometry (HRMS) and an in silico structure search, to identify compounds likely to cause false-positive results. Hundred false-positive IA specimens for AMP and/or MDMA were analyzed by an Agilent 6230 time-of-flight (TOF) mass spectrometer. Separately, SciFinder (Chemical Abstracts) was used as an in silico structure search to generate a library of compounds that are known to cross-react with AMP/MDMA IAs. Chemical formulas and exact masses of 145 structures were then compared against masses identified by TOF. Compounds known to have cross-reactivity with the IAs were identified in the structure-based search. The chemical formulas and exact masses of 145 structures (of 20 chemical formulas) were compared against masses identified by TOF. Urine analysis by HRMS correlates accurate mass with chemical formulae, but provides little information regarding compound structure. Structural data of targeted antigens can be utilized to correlate HRMS-derived chemical formulas with structural analogs.

  9. Construction and simulation of a multi-reflection time-of-flight mass spectrometer at the University of Notre Dame

    NASA Astrophysics Data System (ADS)

    Schultz, B. E.; Kelly, J. M.; Nicoloff, C.; Long, J.; Ryan, S.; Brodeur, M.

    2016-06-01

    One of the most significant problems in the production of rare isotopes is the simultaneous production of contaminants, often time isobaric. Thus, a high-resolution beam purification method is required which needs to be compatible with both the low yield and short half-life of the desired radionuclide. A multi-reflection time-of-flight mass spectrometer meets all these criteria, in addition to boasting a smaller footprint relative to traditional separator dipole magnets. Such a device is currently under construction at the University of Notre Dame and is intended to be coupled to the IG-ISOL source of the planned cyclotron facility. The motivation and conceptual design are presented, as well as the status of simulations to determine the feasibility of using a Bradbury-Nielsen gate for bunching ion beams during initial system testing.

  10. First Isochronous Time-of-Flight Mass Measurements of Short-Lived Projectile Fragments in the ESR

    SciTech Connect

    Stadlmann, J.; Geissel, H.; Hausmann, M.; Nolden, F.; Radon, T.; Schatz, H.; Scheidenberger, C.; Attallah, F.; Beckert, K.; Bosch, F.; Falch, M.; Franczak, B.; Franzke, B.; Kerscher, Th.; Klepper, O.; Kluge, H.J.; Kozhuharov, C.; Loebner, K.E.G.; Muenzenberg, G.; Novikov, Yu.N.; Steck, M.; Sun, Z.; Suemmerer, K.; Weick, H.; Wollnik, H.

    2000-12-31

    A new method for precise mass measurements of short-lived hot nuclei is presented. These nuclei were produced via projectile fragmentation, separated with the FRS and injected into the storage ring ESR being operated in the isochronous mode. The revolution time of the ions is measured with a time-of-flight detector sensitive to single particles. This new method allows access to exotic nuclei with half-lives in the microsecond region. First results from this novel method obtained with measurements on neutron-deficient fragments of a chromium primary beam with half-lives down to 50 ms are reported. A precision of {delta}m/m {<=} 5 {center_dot} 10{sup -6} has been achieved.

  11. Structural calculations and experimental detection of small Ga mS n clusters using time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    BelBruno, J. J.; Sanville, E.; Burnin, A.; Muhangi, A. K.; Malyutin, A.

    2009-08-01

    Ga mS n clusters were generated by laser ablation of a solid sample of Ga 2S 3. The resulting molecules were analyzed in a time-of-flight mass spectrometer. In addition to atomic species, the spectra exhibited evidence for the existence of GaS3+, GaS4+, GaS5+, and GaS6+ clusters. The potential neutral and cationic structures of the observed Ga mS n clusters were computationally investigated using a density-functional approach. Reference is made to the kinetic pathways required for production of clusters from the starting point of the stoichiometric molecule or molecular ion. Cluster atomization enthalpies are compared with bulk values from the literature.

  12. Ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry analysis of icariside II metabolites in rats.

    PubMed

    Sun, E; Xu, Fengjuan; Qian, Qian; Cui, Li; Tan, Xiaobin; Jia, Xiaobin

    2014-01-01

    The possible metabolic pathways of icariside II were proposed. An ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry method was used for analysing the faecal, bile, plasma and urine samples of rats administrated with icariside II. In all, 27 metabolites were identified in the biosamples. Of these, 20, including F1-F12, D3, D4, D6, D7-D9 and M3, M4, were, to our knowledge, reported for the first time. The results indicated that icariside II was metabolised via desugarisation, dehydrogenation, hydrogenation, hydroxylation, demethylation, glucuronidation, dehydration and glycosylation pathways in vivo. Specific hydrolysis of 7-O glucosides in the gut lumen and glucuronic acid conjugation in the liver were considered as the main physiologic processes of icariside II. This study revealed the possible metabolite profiles of icariside II in rats. PMID:25076022

  13. Lipid imaging by gold cluster time-of-flight secondary ion mass spectrometry: application to Duchenne muscular dystrophy.

    PubMed

    Touboul, David; Brunelle, Alain; Halgand, Frédéric; De La Porte, Sabine; Laprévote, Olivier

    2005-07-01

    Imaging with time-of-flight secondary ion mass spectrometry (TOF-SIMS) has expanded very rapidly with the development of gold cluster ion sources (Au(3+)). It is now possible to acquire ion density maps (ion images) on a tissue section without any treatment and with a lateral resolution of few micrometers. In this article, we have taken advantage of this technique to study the degeneration/regeneration process in muscles of a Duchenne muscular dystrophy model mouse. Specific distribution of different lipid classes (fatty acids, triglycerides, phospholipids, tocopherol, coenzyme Q9, and cholesterol) allows us to distinguish three different regions on a mouse leg section: one is destroyed, another is degenerating (oxidative stress and deregulation of the phosphoinositol cycle), and the last one is stable. TOF-SIMS imaging shows the ability to localize directly on a tissue section a great number of lipid compounds that reflect the state of the cellular metabolism. PMID:15834124

  14. Chemical Analysis of the Chinese Liquor Luzhoulaojiao by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry

    PubMed Central

    Yao, Feng; Yi, Bin; Shen, Caihong; Tao, Fei; Liu, Yumin; Lin, Zhixin; Xu, Ping

    2015-01-01

    Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here, and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors. PMID:25857434

  15. Chemical Analysis of the Chinese Liquor Luzhoulaojiao by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Yao, Feng; Yi, Bin; Shen, Caihong; Tao, Fei; Liu, Yumin; Lin, Zhixin; Xu, Ping

    2015-04-01

    Luzhoulaojiao liquor is a type of Chinese liquor that dates back hundreds of years, but whose precise chemical composition remains unknown. This paper describes the screening of the liquor and the identification of its compounds using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOF-MS). Samples were prepared by both liquid-liquid extraction and solid-phase microextraction, which facilitated the detection of thousands of compounds in the liquor, thus demonstrating the superior performance of the proposed method over those reported in previous studies. A total of 320 compounds were common to all 18 types of Luzhoulaojiao liquor studied here, and 13 abundant and potentially bioactive compounds were further quantified. The results indicated that the high-performance method presented here is well suited for the detection and identification of compounds in liquors. This study also contributes to enriching our knowledge of the contents of Chinese liquors.

  16. Potato glycoalkaloids in soil-optimising liquid chromatography-time-of-flight mass spectrometry for quantitative studies.

    PubMed

    Jensen, Pia H; Juhler, René K; Nielsen, Nikoline J; Hansen, Thomas H; Strobel, Bjarne W; Jacobsen, Ole S; Nielsen, John; Hansen, Hans Christian B

    2008-02-22

    Potato glycoalkaloids are produced in high amounts in potato fields during the growth season and losses to soil potentially impact shallow groundwater and via tiles to fresh water ecosystems. A quantitative liquid chromatography-electrospray ionization time-of-flight mass spectrometry (LC-ESI-TOF-MS) method for determination and quantification of potato glycoalkaloids and their metabolites in aqueous soil extracts was developed. The LC-ESI-TOF-MS method had linearities up to 2000microg/L for alpha-solanine and alpha-chaconine and up to 760microg/L for solanidine. No matrix effect was observed, and the detection limits found were in the range 2.2-4.7microg/L. The method enabled quantification of the potato glycoalkaloids in environmental samples.

  17. Letter: A method for the chromatic aberration correction of a laser time of-flight mass analyzer.

    PubMed

    Sysoeva, Elizaveta A; Sysoev, Alexander A

    2016-01-01

    The new ion-optical system of the laser time-of-flight (TOF) mass spectrometer on the basis of two tandem wedge-shape reflectors has been offered and implemented. A new method of correcting chromatic aberration by the ion energy was proposed that used a wire electrode unit with adjustable potentials. This unit allows one to adjust the local TOF of the ions in a narrow energy range ± (1-2)% within the total ion packet with an energy spread of ± 20%. The method reduces the duration of the ion packets by up to 1.5ns, which enables us to obtain the restriction of resolution at a level not worse than R ~ 10500 for a TOF ~35 µs. The aim of the project is to increase the separation of isobaric ions to improve the limit of detection of the laser TOF-MS for the analysis of high-purity samples. PMID:27553736

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  19. Identification of adulteration in milk by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Cozzolino, R; Passalacqua, S; Salemi, S; Malvagna, P; Spina, E; Garozzo, D

    2001-09-01

    The development is described of a rapid, simply and accurate analytical method aimed at evaluating both the presence of cow milk in either raw ewe and water buffalo milk samples employed in industrial processes and the addition of powdered milk to samples of fresh raw milk, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The presence of adulteration is defined by evaluating the protein patterns coming from the most abundant whey proteins, alpha-lactalbumin and beta-lactoglobulin, used as molecular markers. As no pretreatment of the milk samples is required and owing to the speed and ease of use of MALDI-MS the proposed analytical protocol can be used as a routine strategy for the identification of possible adulteration of the raw fresh milk samples that the dairy industry receives from producers every day.

  20. Screening and identification of various components in Thalictrum fortunei using a combination of liquid chromatography/time-of-flight tandem mass spectrometry.

    PubMed

    Cheng, H X; Zeng, Y C; Jia, B Y; Fang, C F; Cheng, W M

    2012-02-01

    An approach for screening and identification of various components in a traditional Chinese medicine (TCM), using a combination of LC/TOF-MS technique was described in this paper. The chemical profile of Thalictrum fortunei, well-known in TCM, was studied using the established method. The possibilities of screening and identifying non-target components inside TCM with modern data acquisition methods of acceleration time of flight mass spectrometers, such as data-dependent MS to MS/MS switching were investigated. As a result, 27 components were identified. This study was aimed to screen and identify the main components of T. fortunei using LC/TOF-MS, expecting to provide a rapid, sensitive, economical and systematical method for the identification and further quality evaluation of TCM preparation.

  1. A field-programmable-gate-array based time digitizer for the time-of-flight mass spectrometry.

    PubMed

    Ye, Chunfeng; Zhao, Lei; Zhou, Zhongyue; Liu, Shubin; An, Qi

    2014-04-01

    The time-of-flight (TOF) mass spectrometry is one of the most widely used techniques to get information about the composition and structure of compounds. The time digitizer, based on time-to-digital conversion, is one of the important parts in modern TOF mass spectrometry, which is often implemented with analog circuitry or application-specific-integrated-circuit (ASIC) devices. However, it is difficult to achieve a high density with the analog approach. Furthermore, ASIC requires a long design cycle and the function cannot be easily revised for different applications. In this work, we present a highly flexible, accurate, yet low-costing design of time digitizer which is based on a field-programmable-gate-array (FPGA) and time interpolation method. Test results indicate that the bin size of this time digitizer is 390 ps with an average standard deviation (about 150 ps). The differential nonlinearity is in the range of -0.10 to +0.05 LSB (least significant bit), and the measurement time range is larger than 107 s. Compared with other techniques, it reduces the system complexity while providing a good flexibility. In addition, this technique can also accommodate one or more STOP pulse measurements for each START pulse reference, enabling measurement of multiple times-of-flight with a common start trigger. Besides, a time stamp is recorded for each input pulse, rendering this time digitizer versatile in other applications. Moreover, because of the programmable characteristic of a FPGA, more functions can be integrated in the time digitizer, such as a trigger function, data transfer interface; the parameters such as the number of the channels. The measurement range can also be modified according to different requirements.

  2. A field-programmable-gate-array based time digitizer for the time-of-flight mass spectrometry.

    PubMed

    Ye, Chunfeng; Zhao, Lei; Zhou, Zhongyue; Liu, Shubin; An, Qi

    2014-04-01

    The time-of-flight (TOF) mass spectrometry is one of the most widely used techniques to get information about the composition and structure of compounds. The time digitizer, based on time-to-digital conversion, is one of the important parts in modern TOF mass spectrometry, which is often implemented with analog circuitry or application-specific-integrated-circuit (ASIC) devices. However, it is difficult to achieve a high density with the analog approach. Furthermore, ASIC requires a long design cycle and the function cannot be easily revised for different applications. In this work, we present a highly flexible, accurate, yet low-costing design of time digitizer which is based on a field-programmable-gate-array (FPGA) and time interpolation method. Test results indicate that the bin size of this time digitizer is 390 ps with an average standard deviation (about 150 ps). The differential nonlinearity is in the range of -0.10 to +0.05 LSB (least significant bit), and the measurement time range is larger than 107 s. Compared with other techniques, it reduces the system complexity while providing a good flexibility. In addition, this technique can also accommodate one or more STOP pulse measurements for each START pulse reference, enabling measurement of multiple times-of-flight with a common start trigger. Besides, a time stamp is recorded for each input pulse, rendering this time digitizer versatile in other applications. Moreover, because of the programmable characteristic of a FPGA, more functions can be integrated in the time digitizer, such as a trigger function, data transfer interface; the parameters such as the number of the channels. The measurement range can also be modified according to different requirements. PMID:24784667

  3. Time-of-flight SIMS/MSRI reflectron mass analyzer and method

    DOEpatents

    Smentkowski, Vincent S.; Gruen, Dieter M.; Krauss, Alan R.; Schultz, J. Albert; Holecek, John C.

    1999-12-28

    A method and apparatus for analyzing the surface characteristics of a sample by Secondary Ion Mass Spectroscopy (SIMS) and Mass Spectroscopy of Recoiled Ions (MSRI) is provided. The method includes detecting back scattered primary ions, low energy ejected species, and high energy ejected species by ion beam surface analysis techniques comprising positioning a ToF SIMS/MSRI mass analyzer at a predetermined angle .theta., where .theta. is the angle between the horizontal axis of the mass analyzer and the undeflected primary ion beam line, and applying a specific voltage to the back ring of the analyzer. Preferably, .theta. is less than or equal to about 120.degree. and, more preferably, equal to 74.degree.. For positive ion analysis, the extractor, lens, and front ring of the reflectron are set at negative high voltages (-HV). The back ring of the reflectron is set at greater than about +700V for MSRI measurements and between the range of about +15 V and about +50V for SIMS measurements. The method further comprises inverting the polarity of the potentials applied to the extractor, lens, front ring, and back ring to obtain negative ion SIMS and/or MSRI data.

  4. Accurate screening for synthetic preservatives in beverage using high performance liquid chromatography with time-of-flight mass spectrometry.

    PubMed

    Li, Xiu Qin; Zhang, Feng; Sun, Yan Yan; Yong, Wei; Chu, Xiao Gang; Fang, Yan Yan; Zweigenbaum, Jerry

    2008-02-11

    In this study, liquid chromatography time-of-flight mass spectrometry (HPLC/TOF-MS) is applied to qualitation and quantitation of 18 synthetic preservatives in beverage. The identification by HPLC/TOF-MS is accomplished with the accurate mass (the subsequent generated empirical formula) of the protonated molecules [M+H]+ or the deprotonated molecules [M-H]-, along with the accurate mass of their main fragment ions. In order to obtain sufficient sensitivity for quantitation purposes (using the protonated or deprotonated molecule) and additional qualitative mass spectrum information provided by the fragments ions, segment program of fragmentor voltages is designed in positive and negative ion mode, respectively. Accurate mass measurements are highly useful in the complex sample analyses since they allow us to achieve a high degree of specificity, often needed when other interferents are present in the matrix. The mass accuracy typically obtained is routinely better than 3 ppm. The 18 compounds behave linearly in the 0.005-5.0mg.kg(-1) concentration range, with correlation coefficient >0.996. The recoveries at the tested concentrations of 1.0mg.kg(-1)-100mg.kg(-1) are 81-106%, with coefficients of variation <7.5%. Limits of detection (LODs) range from 0.0005 to 0.05 mg.kg(-1), which are far below the required maximum residue level (MRL) for these preservatives in foodstuff. The method is suitable for routine quantitative and qualitative analyses of synthetic preservatives in foodstuff.

  5. A gated atmospheric pressure drift tube ion mobility spectrometer-time-of-flight mass spectrometer.

    PubMed

    Heptner, Andre; Reinecke, Tobias; Langejuergen, Jens; Zimmermann, Stefan

    2014-08-22

    Identifying the compounds of an unknown gas mixture by using an ion mobility spectrometer (IMS) is a difficult task, because several ion species can be generated in the ionization process. One method to analyze the occurring peaks in an IMS spectrum is coupling an IMS to a mass spectrometer (MS). In our setup we coupled a (3)H drift tube IMS to a Bruker micrOTOF II. Therefore, the detector plate of the IMS is pierced and a transfer capillary is inserted. The ions are transferred via gas flow and electric fields into the MS. The transmission of the ions through the transfer capillary can be shuttered very precisely by increasing the electric potential of the detector generating a repulsive electric field. Thus, it is possible to transfer single ion clouds of generated IMS spectra into the mass spectrometer where a corresponding mass spectrum is generated. In this work we analyze the positive and negative IMS spectra of single analytes as well as gas mixtures and characterize the occurring ion species. PMID:25015244

  6. A gated atmospheric pressure drift tube ion mobility spectrometer-time-of-flight mass spectrometer.

    PubMed

    Heptner, Andre; Reinecke, Tobias; Langejuergen, Jens; Zimmermann, Stefan

    2014-08-22

    Identifying the compounds of an unknown gas mixture by using an ion mobility spectrometer (IMS) is a difficult task, because several ion species can be generated in the ionization process. One method to analyze the occurring peaks in an IMS spectrum is coupling an IMS to a mass spectrometer (MS). In our setup we coupled a (3)H drift tube IMS to a Bruker micrOTOF II. Therefore, the detector plate of the IMS is pierced and a transfer capillary is inserted. The ions are transferred via gas flow and electric fields into the MS. The transmission of the ions through the transfer capillary can be shuttered very precisely by increasing the electric potential of the detector generating a repulsive electric field. Thus, it is possible to transfer single ion clouds of generated IMS spectra into the mass spectrometer where a corresponding mass spectrum is generated. In this work we analyze the positive and negative IMS spectra of single analytes as well as gas mixtures and characterize the occurring ion species.

  7. Biological tissue imaging with a hybrid cluster SIMS quadrupole time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Carado, A.; Kozole, J.; Passarelli, M.; Winograd, N.; Loboda, A.; Bunch, J.; Wingate, J.; Hankin, J.; Murphy, R.

    2008-12-01

    A 20 keV C 60+ ion source was mounted onto a commercial MALDI/electrospray orthogonal ToF mass spectrometer. Cross-sectional mouse brain and lung slices between 5 and 10 μm prepared by cryostat sectioning were successfully imaged using a DC C 60+ primary ion beam at a spot size of 100 μm. Analysis was performed at room temperature following vacuum drying. An abundance of ions were mapped in all samples, many whose identity can only be found using the MS/MS functionality. We have successfully identified and imaged localizations of diacylglycerol (DAG) ions - 1-palmitoyl-2-oleoyl-glycerol ( m/ z+ 577.5) and 1,2-dioleoyl-glycerol ( m/ z+ 603.5) - in lung tissue. The mouse brain slice revealed strong, distinct localizations of many ions revealing the potential for this technique for biological imaging. Ions throughout the mass range of m/ z+ 50-800 were collected in sufficient quantities to permit unambiguous chemical mapping. Mass resolutions of 12,000 or greater were routinely obtained allowing for more accurate ion mapping than typically seen with ToF-SIMS image analysis.

  8. An electrodynamic ion funnel for electrospray ionization source based time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Bhushan, K. G.; Rao, K. C.; Sule, U.; Reddy, P.; Rodrigues, S. M.; Gaikwad, D. T.; Mukundhan, R.; Gupta, S. K.

    2016-04-01

    An electrodynamic ion funnel has been developed for improving the sensitivity of electrospray ionization sources widely used in the mass spectrometric study of proteins and other biological macromolecules. The ion funnel consists of 52 electrodes and works under the combined influence of RF and DC voltages in the pressure range of 0.1 to 5 mbar. A novel feature of this ion funnel is the specific shape of the exit electrode that improves transmission of lower mass ions by reducing the depth of effective trapping potentials. In this paper, we report on the optimization of the ion funnel design using ion trajectory simulation software SIMION 8.0 especially in the mass range 500–5000 amu, followed by experimental observations of the ion transmission from the electrospray interface. It is seen that the electrospray-ion funnel combination greatly enhances the transmission when compared with an electrospray-skimmer interface. Ion currents > 1 nA could be obtained at the exit of the ion funnel for dilute Streptomycin Sulphate (~ 1500 amu) solution with the ion funnel operating in the 500–900 kHz frequency range, amplitude of 70 Vp‑p, under a DC gradient of about 20 Volts/cm at a background pressure of 0.3 mbar. Details of the construction of the ion funnel along with the experimental results are presented.

  9. A two-phase approach to Fourier transform ion mobility time-of-flight mass spectrometry.

    PubMed

    Clowers, Brian H; Siems, William F; Yu, Zhihao; Davis, Austen L

    2015-10-21

    It is well known that the duty cycle of common drift-tube ion mobility experiments is often below 1%. However, multiplexing approaches such as Fourier and Hadamard pulsing schemes have been shown to independently enhance the throughput of ion mobility spectrometry (IMS) experiments to levels that approach 50%. While challenges remain to their broad scale implementation we describe a new Fourier transform (FT) IMS experiment that is directly compatible with standard drift tube ion mobility mass spectrometers (DT-IMMS). Compared to previous FT-IMS experiments, our new approach requires only a single gate and circumvents the need for signal apodization by combining data from two frequency pulsing sequences 180° out of phase. Assessment of our initial results highlights an increase in signal-to-noise (SNR) relative to both previous implementations FT-IMS experiments and signal averaged (SA) experiments. For select tetraalkylammonium salts SNR improvements of more than one order of magnitude are routinely possible. To explore the performance metrics associated with the technique a number of experimental variables were systematically altered including frequency sweep range, sweep time, and data acquisition time. Using this experimental design we present the key aspects, considerations, and minimum resources necessary for other IMS researchers to incorporate this operational mode into their research. The two-phase FT-IMMS technique offers a tractable mechanism to enhance sensitivity for IMMS measurements and its broad-scale adoption by IMMS researchers promises to enhance the acquisition speed for mobility measurements using hybrid instrumentation.

  10. Neutron Energy and Time-of-flight Spectra Behind the Lateral Shield of a High Energy Electron Accelerator Beam Dump, Part II: Monte Carlo Simulations

    SciTech Connect

    Roesler, Stefan

    2002-09-19

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  11. Calculation of Neutron Time-of-Flight and Energy Spectra Behind Thick Shielding of an Electron Accelerator and Comparison to Experimental Data

    NASA Astrophysics Data System (ADS)

    Roesler, S.

    2002-05-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  12. Calculation of Neutron Time-of-Flight and Energy Spectra Behind Thick Shielding of an Electron Accelerator and Comparison to Experimental Data

    SciTech Connect

    Roesler, Stefan

    2002-05-06

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  13. High temperature gas chromatography-time-of-flight-mass spectrometry (HTGC-ToF-MS) for high-boiling compounds.

    PubMed

    Sutton, P A; Rowland, S J

    2012-06-22

    High temperature gas chromatography (HTGC) is a routine technique for the analysis of high boiling compounds which are eluted from the column with oven cycling up to > 400 °C. In contrast, the coupling of HTGC with mass spectrometry (HTGC-MS) has received relatively little attention. This may be due to the availability of GC columns, mass spectrometers and accessories that are able to withstand constant high temperature cycling. We have assembled a HTGC-time of flight-MS (HTGC-ToF-MS) system from readily available products that is capable of rapid (<25 min) analysis of ∼C₁₀₋₁₀₀ hydrocarbon boiling equivalents and full mass spectral data recording up to m/z 1850. Here we report initial results from the analysis of diverse substrates including:long-chain (> C₆₀) n-alkanes, n-acid methyl esters up to C₆₄, triacylglycerides (TAGs) with molecular and fragment ions in a single analysis, intact wax esters from C₄₀₋₆₄, C₈₀ glycerol alkyl glycerol tetraethers (GDGTs), and C₃₃₋₄₄ metallated porphyrins. Mass spectrometry at 430 °C was achievable on a routine basis without significant thermal degradation of analytes. The method is applicable to analysis of a wide range of industrial, environmental, biological, geochemical and other samples where high molecular weight analytes are of interest.

  14. Use of proton transfer reaction time-of-flight mass spectrometry for quantitative monitoring of toxic nitramines in the environment

    NASA Astrophysics Data System (ADS)

    Wisthaler, A.; Zhu, L.; Stenstrøm, Y.; Nielsen, C. J.

    2014-12-01

    Naturally occurring aliphatic amines and industrially emitted aromatic amines and alkanolamines produce toxic nitramines, (R1R2)-N-NO2, when photo-oxidized in the atmosphere in the presence of nitrogen oxides (NOx). Particular concerns arise from amine-based CO2 capture where the amine solution may get nitrated by NOx in the flue gas. An on-line analytical technique for measuring nitramines in industrial emissions and in ambient air is thus in high demand. Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) is a state-of-the-art technique for on-line measurements of volatile organic compounds (VOCs) in air. Herein, we report on the use of high mass resolution proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) for on-line analysis of nitramines. We generated a mass spectral library from a series of nitramines and investigated the analytical performance of PTR-ToF-MS in terms of sensitivity, precision, accuracy and detection limit. We will discuss limitations of the innovative technique and propose measurement strategies for future emission and ambient measurements.

  15. New long term metabolite in human urine for metenolone misuse by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    He, Genye; Yang, Sheng; Lu, Jianghai; Xu, Youxuan

    2016-01-01

    In this study, metenolone metabolic profiles were investigated. Metenolone was administered to one healthy male volunteer. Liquid-liquid extraction and direct-injection were applied to processing urine samples. Urinary extracts were analyzed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOFMS) using full scan and product ion scan with accurate mass measurement for the first time. Due to the lack of useful fragment ion for structural elucidation, GC-MS instrumentation was employed to obtain structural details of the trimethylsilylated phase I metabolite released after hydrolysis, and the EI mass spectrum was always informative in steroidal structure studies owing to more useful fragment ions than the ESI mass spectrum. 16 metabolites including 6 glucuronide and 9 unreported sulfate conjugates were characterized and tentatively identified. All the metabolites were evaluated in terms of how long they could be detected. The sulfate conjugate S6 (1-methylen-5α-androst-3,17-dione-2ξ-sulfate) was considered to be a new long term metabolite for metenolone misuse that could be detected 40 days by liquid-liquid extraction and up to 30 days by direct-injection analysis after oral administration.

  16. An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, F.; Bönisch, H.; Engel, A.

    2015-09-01

    We present the characterization and application of a new gas chromatography-time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δ m of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 Th/Th and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found around 5 ppm after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits were as low as a few femtograms as mass traces could be made highly specific for selected molecule fragments with the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. The TOFMS was found to be linear within a concentration range from about 1 pg to 1 ng of analyte per Liter of air. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straight-forward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well-suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, low resolution quadrupole MS and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

  17. An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air

    NASA Astrophysics Data System (ADS)

    Obersteiner, F.; Bönisch, H.; Engel, A.

    2016-01-01

    We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range.

  18. Electron Capture Dissociation of Sodium-Adducted Peptides on a Modified Quadrupole/Time-of-Flight Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Voinov, Valery G.; Hoffman, Peter D.; Bennett, Samuel E.; Beckman, Joseph S.; Barofsky, Douglas F.

    2015-12-01

    Electron capture dissociation (ECD), which generally preserves the position of labile post-translational modifications, can be a powerful method for de novo sequencing of proteins and peptides. In this report, ECD product-ion mass spectra of singly and doubly sodiated, nonphosphorylated, and phosphorylated peptides are presented and compared with the ECD mass spectra of their protonated counterparts. ECD of doubly charged, singly sodiated peptides yielded essentially the same sequence information as was produced by the corresponding doubly protonated peptides. The presence of several sodium binding sites on the polypeptide backbone, however, resulted in more complicated spectra. This situation is aggravated by the zwitterionic equilibrium of the free acid peptide precursors. The product-ion spectra of doubly and triply charged peptides possessing two sodium ions were further complicated by the existence of isomers created by the differential distribution of sodium binding sites. Triply charged, phosphorylated precursors containing one sodium, wherein the sodium is attached exclusively to the PO4 group, were found to be as useful for sequence analysis as the fully protonated species. Although sodium adducts are generally minimized during sample preparation, it appears that they can nonetheless provide useful sequence information. Additionally, they enable straightforward identification of a peptide's charge state, even on low-resolution instruments. The experiments were carried out using a radio frequency-free electromagnetostatic cell retrofitted into the collision-induced dissociation (CID) section of a hybrid quadrupole/time-of-flight tandem mass spectrometer.

  19. Qualitative analysis of halogenated organic contaminants in American eel by gas chromatography/time-of-flight mass spectrometry.

    PubMed

    Byer, Jonathan D; Pacepavicius, Grazina; Lebeuf, Michel; Brown, R Stephen; Backus, Sean; Hodson, Peter V; Alaee, Mehran

    2014-12-01

    Target compound analysis with scanning mass spectrometers such as quadrupole or magnetic sector instruments is used extensively in environmental chemistry because of the selectivity, sensitivity, and robustness. Yet, target compound analysis selectively ignores the majority of compounds present in a sample, especially in complex matrices like fish. In this study, time-of-flight mass spectrometry was used to screen for and identify halogenated compounds in American eels (Anguilla rostrata). Individual and then pooled eel samples were analysed using electron ionization and electron capture negative ionization (ECNI) modes. Eels were differentiated by principal component analysis of chemical profiles and were grouped corresponding to their capture location, all with a single instrument injection per sample. Bromine containing compounds were further investigated by taking advantage of the selectivity of ECNI by utilizing the Br(-) ion m/z 79 and 81. A total of 51 brominated compounds were detected and their identities were attempted by authentic standards, library searching, and/or chemical formula prediction based on accurate mass measurements. Several PBDEs were identified in the samples, and the majority of the non-PBDEs identified were bromophenols, bromoanisoles, and bromobenzenes. These classes of compounds are synthesized for use in flame retardant production either as intermediates or as final products. However, their occurrence in eels was most likely the result of metabolism or break-down products of high production volume flame retardants like polybrominated diphenyl ethers and bromophenoxy compounds.

  20. Searching for non-target chlorinated pesticides in food by liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    García-Reyes, Juan F; Ferrer, Imma; Thurman, E Michael; Molina-Díaz, Antonio; Fernández-Alba, Amadeo R

    2005-01-01

    In this study the unique and most salient features of liquid chromatography/time-of-flight-mass spectrometry (LC/TOFMS) were applied for the identification of non-target chlorinated pesticides in complex food extracts 'a priori', i.e., without the use of standards. The combination of high sensitivity full-scan spectra incorporating accurate mass measurements (routinely better than 2 ppm accuracy) of the protonated molecules with the evidence from resolved isotopic clusters provides the ability to obtain a reduced number of possible elemental compositions (typically 1-2). Databases were then used to find the identity of the suspected species using the elemental composition as a searching criterion. The accurate mass and the generated elemental composition of characteristic fragment ions of the suspected species provide further evidence for the proposed species. With this approach we have identified the following chlorinated pesticides in different market-purchased fruit and vegetable extracts: Chlorotoluron (tomato), iprodione (apple), and procymidone (grapes). Finally, the confirmation and quantitation of these suspected species were successfully accomplished with standards. Other unknown compounds could be partially identified based on the data obtained within this study. As an example, a chlorinated species ('m/z 311') is discussed; the elemental composition and possible structures were proposed and the analytical potential, advantages and disadvantages of the proposed approach critically discussed.

  1. Electron Capture Dissociation of Sodium-Adducted Peptides on a Modified Quadrupole/Time-of-Flight Mass Spectrometer.

    PubMed

    Voinov, Valery G; Hoffman, Peter D; Bennett, Samuel E; Beckman, Joseph S; Barofsky, Douglas F

    2015-12-01

    Electron capture dissociation (ECD), which generally preserves the position of labile post-translational modifications, can be a powerful method for de novo sequencing of proteins and peptides. In this report, ECD product-ion mass spectra of singly and doubly sodiated, nonphosphorylated, and phosphorylated peptides are presented and compared with the ECD mass spectra of their protonated counterparts. ECD of doubly charged, singly sodiated peptides yielded essentially the same sequence information as was produced by the corresponding doubly protonated peptides. The presence of several sodium binding sites on the polypeptide backbone, however, resulted in more complicated spectra. This situation is aggravated by the zwitterionic equilibrium of the free acid peptide precursors. The product-ion spectra of doubly and triply charged peptides possessing two sodium ions were further complicated by the existence of isomers created by the differential distribution of sodium binding sites. Triply charged, phosphorylated precursors containing one sodium, wherein the sodium is attached exclusively to the PO4 group, were found to be as useful for sequence analysis as the fully protonated species. Although sodium adducts are generally minimized during sample preparation, it appears that they can nonetheless provide useful sequence information. Additionally, they enable straightforward identification of a peptide's charge state, even on low-resolution instruments. The experiments were carried out using a radio frequency-free electromagnetostatic cell retrofitted into the collision-induced dissociation (CID) section of a hybrid quadrupole/time-of-flight tandem mass spectrometer. Graphical Abstract ᅟ. PMID:26266643

  2. New Potential Biomarker for Methasterone Misuse in Human Urine by Liquid Chromatography Quadrupole Time of Flight Mass Spectrometry.

    PubMed

    Zhang, Jianli; Lu, Jianghai; Wu, Yun; Wang, Xiaobing; Xu, Youxuan; Zhang, Yinong; Wang, Yan

    2016-01-01

    In this study, methasterone urinary metabolic profiles were investigated by liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF-MS) in full scan and targeted MS/MS modes with accurate mass measurement. A healthy male volunteer was asked to take the drug and liquid-liquid extraction was employed to process urine samples. Chromatographic peaks for potential metabolites were hunted out with the theoretical [M - H](-) as a target ion in a full scan experiment and actual deprotonated ions were studied in targeted MS/MS experiment. Fifteen metabolites including two new sulfates (S1 and S2), three glucuronide conjugates (G2, G6 and G7), and three free metabolites (M2, M4 and M6) were detected for methasterone. Three metabolites involving G4, G5 and M5 were obtained for the first time in human urine samples. Owing to the absence of helpful fragments to elucidate the steroid ring structure of methasterone phase II metabolites, gas chromatography mass spectrometry (GC-MS) was employed to obtain structural information of the trimethylsilylated phase I metabolite released after enzymatic hydrolysis and the potential structure was inferred using a combined MS method. Metabolite detection times were also analyzed and G2 (18-nor-17β-hydroxymethyl-2α, 17α-dimethyl-androst-13-en-3α-ol-ξ-O-glucuronide) was thought to be new potential biomarker for methasterone misuse which can be detected up to 10 days. PMID:27669235

  3. New Potential Biomarker for Methasterone Misuse in Human Urine by Liquid Chromatography Quadrupole Time of Flight Mass Spectrometry

    PubMed Central

    Zhang, Jianli; Lu, Jianghai; Wu, Yun; Wang, Xiaobing; Xu, Youxuan; Zhang, Yinong; Wang, Yan

    2016-01-01

    In this study, methasterone urinary metabolic profiles were investigated by liquid chromatography quadrupole time of flight mass spectrometry (LC-QTOF-MS) in full scan and targeted MS/MS modes with accurate mass measurement. A healthy male volunteer was asked to take the drug and liquid–liquid extraction was employed to process urine samples. Chromatographic peaks for potential metabolites were hunted out with the theoretical [M − H]− as a target ion in a full scan experiment and actual deprotonated ions were studied in targeted MS/MS experiment. Fifteen metabolites including two new sulfates (S1 and S2), three glucuronide conjugates (G2, G6 and G7), and three free metabolites (M2, M4 and M6) were detected for methasterone. Three metabolites involving G4, G5 and M5 were obtained for the first time in human urine samples. Owing to the absence of helpful fragments to elucidate the steroid ring structure of methasterone phase II metabolites, gas chromatography mass spectrometry (GC-MS) was employed to obtain structural information of the trimethylsilylated phase I metabolite released after enzymatic hydrolysis and the potential structure was inferred using a combined MS method. Metabolite detection times were also analyzed and G2 (18-nor-17β-hydroxymethyl-2α, 17α-dimethyl-androst-13-en-3α-ol-ξ-O-glucuronide) was thought to be new potential biomarker for methasterone misuse which can be detected up to 10 days. PMID:27669235

  4. [Separation and identification of beta-casein from Chinese human milk by ion exchange chromatography-matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry].

    PubMed

    Huang, Yu; Ren, Haowei; Liu, Biao; Liu, Ning; Li, Meng; Wang, Dongmao

    2013-05-01

    The selective precipitation of whole casein from skimmed milk was achieved by the addition of calcium salt under acidic pH. The effects of pH, centrifugal force and final concentration of CaCl2 on the separation of casein were studied by measuring the purity of final products using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that casein with the highest purity could be obtained with the pH of 4.3, the centrifugal force of 10 400 g and the final concentration of CaCl2 of 60 mmol/L. The casein was processed with DEAE anion exchange chromatography and three peaks were obtained. Then the third peak (peak III) was identified with Western-Blot method and matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (MALDI-TOF/TOF MS). The identification of Western-Blot showed that peak III can combine with the specificity of human milk beta-casein antibody, and it is proved to be human milk beta-casein. The fingerprints of peak III were nalyzed by Mascot searching, and the sequence coverage was 50%, further supporting it is human milk beta-casein. In conclusion, an effective method to obtain human milk beta-casein from milk samples through DEAE anion exchange chromatography was established, and it is suitable for the proteomics research requirements of the beta-casein from human milk.

  5. Determination of exogenous epigallocatechin gallate peracetate in mouse plasma using liquid chromatography with quadrupole time-of-flight mass spectrometry.

    PubMed

    Chu, Kai On; Man, Gene Chi Wai; Chan, Kwok Ping; Chu, Ching Yan; Chan, Tak Hang; Pang, Chi Pui; Wang, Chi Chiu

    2014-12-01

    A robust method for the quantitation of epigallocatechin gallate peracetate in plasma for pharmacokinetic studies is lacking. We have developed a validated method to quantify this compound using liquid chromatography with quadrupole time-of-flight mass spectrometry with isopropanol and tert-butyl methyl ether (3:10) extraction and thin-layer chromatography purification. The epigallocatechin gallate peracetate-1-(13) C8 isotope was used as an internal standard. The linear range (r(2) > 0.9950) was from 0.05 to 100.00 μg/mL. The lower limit of quantification of the method was 0.05 μg/mL. Reproducibility, coefficient of variation, was between 0.7 and 12.6% (n = 6), accuracy between 83.7 and 104.6% (n = 5), and recovery ranged from 82.4 to 109.0% (n = 4). Ion suppression was approximately 40%. No mass spectral peaks were found to interfere between the standard and internal standard or the blank plasma extracts. Epigallocatechin gallate peracetate in plasma was stably stored at -80°C over three months even after three freeze-thaw cycles. Extracts were stable in the sampler at 4°C for over 48 h. Plasma levels were maintained at 1.36 μg/mL for 360 min after intraorbital intravenous injection at 50 mg/kg in mice. This method can be used to reliably measure epigallocatechin gallate peracetate in plasma for pharmacokinetic studies.

  6. Coupled Space- and Velocity-Focusing in Time-of-Flight Mass Spectrometry-a Comprehensive Theoretical Investigation.

    PubMed

    Cai, Yi-Hong; Lai, Yin-Hung; Wang, Yi-Sheng

    2015-10-01

    A comprehensive theoretical calculation that couples space- and velocity-focusing is developed for optimizing the design of a time-of-flight (TOF) mass spectrometer. Conventional designs for ion sources of TOF mass spectrometers deviate from the optimal condition because the velocity- and space-focusing conditions are considered separately for two ions with simplified equations. The result of a reexamination taking into account all essential ions reveals that the conventional ion source design, especially the length of the ion extraction region, results in poor resolving power. The comprehensive calculation demonstrates that the resolving power increases when the length of the extraction region is shorter than that of the conventional ion source. A numerical analysis indicates that the resolving power dramatically increases when the effective extraction potential compensates for the initial kinetic energy spread of ions. With typically used extraction potentials, the newly optimized ion source improves the resolving power by more than two orders of magnitude compared with the conventional design. This new theoretical interpretation can also be used to predict the optimal extraction potential and extraction delay in conventional ion sources to substantially improve the resolving power. This comprehensive calculation method is effective not only for designing new high-resolution instruments but also for optimizing commercial products.

  7. Rapid assignment of malting barley varieties by matrix-assisted laser desorption-ionisation - Time-of-flight mass spectrometry.

    PubMed

    Šedo, Ondrej; Kořán, Michal; Jakešová, Michaela; Mikulíková, Renata; Boháč, Michal; Zdráhal, Zbyněk

    2016-09-01

    A method for discriminating malting barley varieties based on direct matrix-assisted laser desorption-ionisation - time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting of proteins was developed. Signals corresponding to hordeins were obtained by simple mixing of powdered barley grain with a MALDI matrix solution containing 12.5mgmL(-1) of ferulic acid in an acetonitrile:water:formic acid 50:33:17 v/v/v mixture. Compared to previous attempts at MALDI-TOF mass spectrometric analysis of barley proteins, the extraction and fractionation steps were practically omitted, resulting in a significant reduction in analytical time and costs. The discriminatory power was examined on twenty malting barley varieties and the practicability of the method was tested on sixty barley samples acquired from Pilsner Urquell Brewery. The method is proposed as a rapid tool for variety assignment and purity determination of malting barley that may replace gel electrophoresis currently used for this purpose. PMID:27041307

  8. A strategy for direct identification of protein S-nitrosylation sites by quadrupole time-of-flight mass spectrometry.

    PubMed

    Wang, Yan; Liu, Tong; Wu, Changgong; Li, Hong

    2008-09-01

    S-nitrosylation of proteins serves an important role in regulating diverse cellular processes including signal transduction, DNA repair, and neurotransmission. Identification of S-nitrosylation sites is crucial for understanding the significance of this post-translational modification (PTM) in modulating the function of a protein. However, it is challenging to identify S-nitrosylation sites directly by mass spectrometric (MS) methods due to the labile nature of the S-NO bond. Here we describe a strategy for direct identification of protein S-nitrosylation sites in an electrospray ionization (ESI) quadrupole time-of-flight (QTOF) mass spectrometer without prior chemical derivatization of S-nitrosylated peptides. Both sample buffer composition and MS hardware parameters were carefully adjusted to ensure that S-nitrosylated peptide ions could be analyzed by the QTOF MS with optimal signal/noise ratios. It was crucial that the proteins were preserved in a sample solution containing 1 mM EDTA and 0.1 mM neocuproine at neutral pH. Proteins dissolved in this solution are amenable to in-solution tryptic digestion, which is important for the analysis of biological samples. S-nitrosylated peptides were effectively analyzed by LC/MS/MS on QTOF MS, with an optimized cone voltage of 20 V and collision energy of 4 V. We have successfully applied this method to thioredoxin, a key antioxidant protein, and identified within it an S-nitrosylation site at Cys73.

  9. Metabolic profiles of dioscin in rats revealed by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Zhu, He; Xu, Jin-Di; Mao, Qian; Shen, Hong; Kong, Ming; Chen, Jian-Ping; Li, Song-Lin

    2015-09-01

    Dioscin (DIS), one of the most abundant bioactive steroidal saponins in Dioscorea sp., is used as a complementary medicine to treat coronary disease and angina pectoris in China. Although the pharmacological activities and pharmacokinetics of DIS have been well demonstrated, information regarding the final metabolic fates is very limited. This study investigated the in vivo metabolic profiles of DIS after oral administration by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry method. The structures of the metabolites were identified and tentatively characterized by means of comparing the molecular mass, retention time and fragmentation pattern of the analytes with those of the parent compound. A total of eight metabolites, including seven phase I and one phase II metabolites, were detected and tentatively identified for the first time. Oxidation, deglycosylation and glucuronidation were found to be the major metabolic processes of the compound in rats. In addition, a possible metabolic pathway on the biotransformation of DIS in vivo was proposed. This study provides valuable and new information on the metabolism of DIS, which will be helpful for further understanding its mechanism of action. PMID:25678372

  10. New potential biomarkers for mesterolone misuse in human urine by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Lu, Jianghai; Fernández-Álvarez, María; Yang, Sheng; He, Genye; Xu, Youxuan; Aguilera, Rodigo

    2015-01-01

    In this paper, mesterolone metabolic profiles were investigated carefully. Mesterolone was administered to one healthy male volunteer. Urinary extracts were analyzed by liquid chromatography quadruple time-of-flight mass spectrometry (LC-QTOFMS) for the first time. Liquid-liquid extraction was applied to processing urine samples, and dilute-shoot analyses of intact metabolites were also presented. In LC-QTOFMS analysis, chromatographic peaks for potential metabolites were hunt down by using the theoretical [M-H](-) as target ions in full scan experiment, and their actual deprotonated ions were analyzed in targeted MS/MS mode. Ten metabolites including seven new sulfate and three glucuronide conjugates were found for mesterolone. Because of no useful fragment ion for structural elucidation, gas chromatography-mass spectrometry instrumentation was employed to obtain structural details of the trimethylsilylated phase I metabolite released after solvolysis. Thus, their potential structures were proposed particularly by a combined MS approach. All the metabolites were also evaluated in terms of how long they could be detected, and S1 (1α-methyl-5α-androst-3-one-17β-sulfate) together with S2 (1α-methyl-5α-androst-17-one-3β-sulfate) was detected up to 9 days after oral administration, which could be the new potential biomarkers for mesterolone misuse. PMID:25601687

  11. Global gas chromatography/time-of-flight mass spectrometry (GC/TOFMS)-based metabonomic profiling of lyophilized human feces.

    PubMed

    Phua, Lee Cheng; Koh, Poh Koon; Cheah, Peh Yean; Ho, Han Kiat; Chan, Eric Chun Yong

    2013-10-15

    Gas chromatography mass spectrometry (GC/MS)-based fecal metabonomics represents a powerful systems biology approach for elucidating metabolic biomarkers of lower gastrointestinal tract (GIT) diseases. Unlike metabolic profiling of fecal water, the profiling of complete fecal material remains under-explored. Here, a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) method was developed and validated for the global metabonomic profiling of human feces. Fecal and fecal water metabotypes were also profiled and compared. Additionally, the unclear influence of blood in stool on the fecal metabotype was investigated unprecedentedly. Eighty milligram of lyophilized feces was ultrasonicated with 1mL of methanol:water (8:2) for 30min, followed by centrifugation, drying of supernatant, oximation and trimethylsilylation for 45min. Lyophilized feces demonstrated a more comprehensive metabolic coverage than fecal water, based on the number of chromatographic peaks. Principal component analysis (PCA) indicated occult blood (1mgHb/g feces) exerted a negligible effect on the fecal metabotype. Conversely, a unique metabotype related to feces spiked with gross blood (100mgHb/g feces) was revealed (PCA, R(2)X=0.837, Q(2)=0.794), confirming the potential confounding effect of gross GIT bleeding on the fecal metabotype. This pertinent finding highlights the importance of prudent interpretation of fecal metabonomic data, particularly in GIT diseases where bleeding is prevalent.

  12. Imaging of a tribolayer formed from ionic liquids by laser desorption/ionization-reflectron time-of-flight mass spectrometry.

    PubMed

    Gabler, Christoph; Pittenauer, Ernst; Dörr, Nicole; Allmaier, Günter

    2012-12-18

    For the first time, imaging using laser desorption/ionization (LDI) reflectron time-of-flight (RTOF) mass spectrometry (MS) was demonstrated to be a powerful tool for an offline monitoring of tribometrical experiments directly from disc specimen applying selected ammonium-, phosphonium-, and sulfonium-based ionic liquids (IL) with bis(trifluoromethylsulfonyl)imide as counterion for lubrication. The direct measurement of IL tribolayers by LDI-MS allowed the visualization of the lubricants in the form of the distribution of their intact cations and the anion in and outside the wear scar after the tribometrical experiment with a low degree of in-source generated fragmentation. Besides, also, an oxidation product formed during a tribometrical experiment was detected and located exclusively in the wear track. Comparative data of identical wear tracks were obtained by X-ray photoelectron spectroscopy (XPS) imaging not only enabling the determination of elemental distributions of the IL across the area imaged but also corroborating the mass spectrometry imaging (MSI) data, thus generating multimodal images. Merging data from MSI and XPS imaging exhibited that areas, where iron-fluorine bonds were detected in the wear track, are corresponding to data from LDI-MS imaging showing absence of IL cations and anions.

  13. Comparative metabolomic study of transgenic versus conventional soybean using capillary electrophoresis-time-of-flight mass spectrometry.

    PubMed

    García-Villalba, Rocio; León, Carlos; Dinelli, Giovanni; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto; Garcia-Cañas, Virginia; Cifuentes, Alejandro

    2008-06-27

    In this work, capillary electrophoresis-time-of-flight mass spectrometry (CE-TOF-MS) is proposed to identify and quantify the main metabolites found in transgenic soybean and its corresponding non-transgenic parental line both grown under identical conditions. The procedure includes optimization of metabolites extraction, separation by CE, on-line electrospray-TOF-MS analysis and data evaluation. A large number of extraction procedures and background electrolytes are tested in order to obtain a highly reproducible and sensitive analytical methodology. Using this approach, a large number of metabolites were tentatively identified based on the high mass accuracy provided by TOF-MS analyzer, together with the isotopic pattern and expected electrophoretic mobility of these compounds. In general, the same metabolites and in similar amounts were found in the conventional and transgenic variety. However, significant differences were also observed in some specific cases when the conventional variety was compared with its corresponding transgenic line. The selection of these metabolites as possible biomarkers of transgenic soybean is discussed, although a larger number of samples need to be analyzed in order to validate this point. It is concluded that metabolomic procedures based on CE-MS can open new perspectives in the study of transgenic foods in order to corroborate (or not) the equivalence with their conventional counterparts.

  14. Revealing surface oxidation on the organic semi-conducting single crystal rubrene with time of flight secondary ion mass spectroscopy.

    PubMed

    Thompson, Robert J; Fearn, Sarah; Tan, Ke Jie; Cramer, Hans George; Kloc, Christian L; Curson, Neil J; Mitrofanov, Oleg

    2013-04-14

    To address the question of surface oxidation in organic electronics the chemical composition at the surface of single crystalline rubrene is spatially profiled and analyzed using Time of Flight - Secondary Ion Mass Spectroscopy (ToF-SIMS). It is seen that a uniform oxide (C42H28O) covers the surface while there is an increased concentration of peroxide (C42H28O2) located at crystallographic defects. By analyzing the effects of different primary ions, temperature and sputtering agents the technique of ToF-SIMS is developed as a valuable tool for the study of chemical composition variance both at and below the surface of organic single crystals. The primary ion beams C60(3+) and Bi3(+) are found to be most appropriate for mass spectroscopy and spatial profiling respectively. Depth profiling of the material is successfully undertaken maintaining the molecular integrity to a depth of ~5 μm using an Ar cluster ion source as the sputtering agent. PMID:23455651

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

    EPA Science Inventory

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

  16. Exploration of Inorganic C and N Assimilation by Soil Microbes with Time-of-Flight Secondary Ion Mass Spectrometry†

    PubMed Central

    Cliff, John B.; Gaspar, Daniel J.; Bottomley, Peter J.; Myrold, David D.

    2002-01-01

    Stable C and N isotopes have long been used to examine properties of various C and N cycling processes in soils. Unfortunately, relatively large sample sizes are needed for accurate gas phase isotope ratio mass spectrometric analysis. This limitation has prevented researchers from addressing C and N cycling issues on microbially meaningful scales. Here we explored the use of time-of-flight secondary ion mass spectrometry (TOF-SIMS) to detect 13C and 15N assimilation by individual bacterial cells and to quantify N isotope ratios in bacterial samples and individual fungal hyphae. This was accomplished by measuring the relative abundances of mass 26 (12C14N−) and mass 27 (13C14N− and 12C15N−) ions sputtered with a Ga+ probe from cells adhered to an Si contact slide. TOF-SIMS was successfully used to locate and quantify the relative 15N contents of individual hyphae that grew onto Si contact slides in intimate contact with a model organomineral porous matrix composed of kaolin, straw fragments, and freshly deposited manure that was supplemented with 15NO3−. We observed that the 15N content of fungal hyphae grown on the slides was significantly lower in regions where the hyphae were influenced by N-rich manure than in regions influenced by N-deficient straw. This effect occurred over distances of tens to hundreds of microns. Our data illustrate that TOF-SIMS has the potential to locate N-assimilating microorganisms in soil and to quantify the 15N content of cells that have assimilated 15N-labeled mineral N and shows promise as a tool with which to explore the factors controlling microsite heterogeneities in soil. PMID:12147508

  17. Exploration of Inorganic C and N Assimilation by Soil Microbes with Time-of-Flight Secondary Ion Mass Spectrometry

    SciTech Connect

    Cliff, John B.; Gaspar, Dan J. ); Bottomley, Peter J.; Myrold, David D.

    2002-08-01

    Stable C and N isotopes have long been used to examine properties of various C and N cycling processes in soils. Unfortunately, relatively large sample sizes are needed for accurate gas phase isotope ratio mass spectrometric analysis. This limitation has prevented researchers from addressing C and N cycling issues at microbially meaningful scales. Here we explore the use of time of flight secondary ion mass spectrometry (TOF-SIMS) to detect 13C and 15N assimilation by individual bacterial cells and to quantify N isotope ratios in bacterial samples and individual fungal hyphae. This was accomplished by measuring the relative abundances of mass 26 (12C14N) and mass 27 (13C14N and 12C15N) ions sputtered with a Ga+ probe form cells adhered to a Si contact slide. TOF-SIMS was successfully used to locate and quantify the relative 15N content of individual hyhpae that grew onto Si contact slides in intimate contact with a model organomineral porous matrix composed of kaolin, straw fragments, and freshly deposited manure that was supplemented with 15NO-3. We observed that 15N content of fungal hyphae grown on the slides was significantly lower in regions where the hyhpae were influenced by N-rich manure than in regions influenced by N-deficient straw. This effect occurred over distances of tens of hundreds of microns. Our data illustrates that TOF-SIMS has the potential to locate N assimilating microorganisms in soil, to quantify the 15N content of cells that have assimilated 15N-labeled mineral N, and shows promise as a tool to explore the factors controlling microsite heterogeneities in soil.

  18. Exploration of inorganic C and N assimilation by soil microbes with time-of-flight secondary ion mass spectrometry.

    PubMed

    Cliff, John B; Gaspar, Daniel J; Bottomley, Peter J; Myrold, David D

    2002-08-01

    Stable C and N isotopes have long been used to examine properties of various C and N cycling processes in soils. Unfortunately, relatively large sample sizes are needed for accurate gas phase isotope ratio mass spectrometric analysis. This limitation has prevented researchers from addressing C and N cycling issues on microbially meaningful scales. Here we explored the use of time-of-flight secondary ion mass spectrometry (TOF-SIMS) to detect 13C and 15N assimilation by individual bacterial cells and to quantify N isotope ratios in bacterial samples and individual fungal hyphae. This was accomplished by measuring the relative abundances of mass 26 (12C14N-) and mass 27 (13C14N- and 12C15N-) ions sputtered with a Ga+ probe from cells adhered to an Si contact slide. TOF-SIMS was successfully used to locate and quantify the relative 15N contents of individual hyphae that grew onto Si contact slides in intimate contact with a model organomineral porous matrix composed of kaolin, straw fragments, and freshly deposited manure that was supplemented with 15NO3-. We observed that the 15N content of fungal hyphae grown on the slides was significantly lower in regions where the hyphae were influenced by N-rich manure than in regions influenced by N-deficient straw. This effect occurred over distances of tens to hundreds of microns. Our data illustrate that TOF-SIMS has the potential to locate N-assimilating microorganisms in soil and to quantify the 15N content of cells that have assimilated 15N-labeled mineral N and shows promise as a tool with which to explore the factors controlling microsite heterogeneities in soil.

  19. Insights on Clusters Formation Mechanism by Time of Flight Mass Spectrometry. 2. The Case of Acetone-Water Clusters

    NASA Astrophysics Data System (ADS)

    Apicella, B.; Li, X.; Passaro, M.; Russo, C.

    2016-11-01

    This paper is the second of a series dealing with clusters formation mechanism. In part 1, water clusters with the addition of an electrophilic molecule such as ethanol were studied by Time Of Flight Mass Spectrometry (TOFMS). Mass distributions of molecular clusters of ethanol, water and ethanol-water mixed clusters, were obtained by means of two different ionization methods: Electron Ionization (EI) and picosecond laser Photo-Ionization (PI) at a wavelength of 355 nm. In part 2, the same experimental approach was employed to obtain mass spectra of clusters generated by acetone-water binary mixtures with a different composition. Strong dependence of the mass spectra of clusters with EI and PI on the acetone-water mixing ratio was observed. It was shown that the spectral pattern changes gradually and water-rich cluster signals become fainter while acetone-rich cluster signals become more intensive with increasing acetone concentrations from 0.3% to 40%. Owing to the hydrogen bond acceptor character of acetone, its self-association is discouraged with respect to ethanol. The autocorrelation function (AF) was used to analyze the variation of the water clusters composition with the increase of the acetone concentration in terms of fundamental periodicities. However, although acetone and ethanol present a very different hydrogen-bonding ability, similarly to ethanol-water system, in acetone-water system the formation of water-rich clusters and subsequent metastable fragmentation are the dominant process that determine the clusters distribution, irrespective of the ionization process, while the ionization process significantly affects the acetone-rich clusters distribution.

  20. Insights on Clusters Formation Mechanism by Time of Flight Mass Spectrometry. 2. The Case of Acetone-Water Clusters

    NASA Astrophysics Data System (ADS)

    Apicella, B.; Li, X.; Passaro, M.; Russo, C.

    2016-08-01

    This paper is the second of a series dealing with clusters formation mechanism. In part 1, water clusters with the addition of an electrophilic molecule such as ethanol were studied by Time Of Flight Mass Spectrometry (TOFMS). Mass distributions of molecular clusters of ethanol, water and ethanol-water mixed clusters, were obtained by means of two different ionization methods: Electron Ionization (EI) and picosecond laser Photo-Ionization (PI) at a wavelength of 355 nm. In part 2, the same experimental approach was employed to obtain mass spectra of clusters generated by acetone-water binary mixtures with a different composition. Strong dependence of the mass spectra of clusters with EI and PI on the acetone-water mixing ratio was observed. It was shown that the spectral pattern changes gradually and water-rich cluster signals become fainter while acetone-rich cluster signals become more intensive with increasing acetone concentrations from 0.3% to 40%. Owing to the hydrogen bond acceptor character of acetone, its self-association is discouraged with respect to ethanol. The autocorrelation function (AF) was used to analyze the variation of the water clusters composition with the increase of the acetone concentration in terms of fundamental periodicities. However, although acetone and ethanol present a very different hydrogen-bonding ability, similarly to ethanol-water system, in acetone-water system the formation of water-rich clusters and subsequent metastable fragmentation are the dominant process that determine the clusters distribution, irrespective of the ionization process, while the ionization process significantly affects the acetone-rich clusters distribution.

  1. Characterization and quantitative analysis of surfactants in textile wastewater by liquid chromatography/quadrupole-time-of-flight mass spectrometry.

    PubMed

    González, Susana; Petrović, Mira; Radetic, Maja; Jovancic, Petar; Ilic, Vesna; Barceló, Damià

    2008-05-01

    A method based on the application of ultra-performance liquid chromatography (UPLC) coupled to hybrid quadrupole-time-of-flight mass spectrometry (QqTOF-MS) with an electrospray (ESI) interface has been developed for the screening and confirmation of several anionic and non-ionic surfactants: linear alkylbenzenesulfonates (LAS), alkylsulfate (AS), alkylethersulfate (AES), dihexyl sulfosuccinate (DHSS), alcohol ethoxylates (AEOs), coconut diethanolamide (CDEA), nonylphenol ethoxylates (NPEOs), and their degradation products (nonylphenol carboxylate (NPEC), octylphenol carboxylate (OPEC), 4-nonylphenol (NP), 4-octylphenol (OP) and NPEO sulfate (NPEO-SO4). The developed methodology permits reliable quantification combined with a high accuracy confirmation based on the accurate mass of the (de)protonated molecules in the TOFMS mode. For further confirmation of the identity of the detected compounds the QqTOF mode was used. Accurate masses of product ions obtained by performing collision-induced dissociation (CID) of the (de)protonated molecules of parent compounds were matched with the ions obtained for a standard solution. The method was applied for the quantitative analysis and high accuracy confirmation of surfactants in complex mixtures in effluents from the textile industry. Positive identification of the target compounds was based on accurate mass measurement of the base peak, at least one product ion and the LC retention time of the analyte compared with that of a standard. The most frequently surfactants found in these textile effluents were NPEO and NPEO-SO4 in concentrations ranging from 0.93 to 5.68 mg/L for NPEO and 0.06 to 4.30 mg/L for NPEO-SO4. AEOs were also identified. PMID:18398847

  2. Investigation of isomeric flavanol structures in black tea thearubigins using ultraperformance liquid chromatography coupled to hybrid quadrupole/ion mobility/time of flight mass spectrometry.

    PubMed

    Yassin, Ghada H; Grun, Christian; Koek, Jean H; Assaf, Khaleel I; Kuhnert, Nikolai

    2014-11-01

    Ultra performance liquid chromatography (UPLC) when coupled to ion mobility (IMS)/orthogonal acceleration time of flight mass spectrometry is a suitable technique for analyzing complex mixtures such as the black tea thearubigins. With the aid of this advanced instrumental analysis, we were able to separate and identify different isomeric components in the complex mixture which could previously not be differentiated by a conventional high performance liquid chromatography/tandem mass spectrometry. In this study, the difference between isomeric structures theasinensins, proanthocyanidins B-type and rutin (quercetin-3O-rutinoside) were studied, and these are present abundantly in many botanical sources. The differentiation between these structures was accomplished according to their acquired mobility drift times differing from the traditional investigations in mass spectrometry, where calculation of theoretical collisional cross sections allowed assignment of the individual isomeric structures. The present work demonstrates UPLC-IMS-MS as an efficient technology for isolating and separating isobaric and isomeric structures existing in complex mixtures discriminating between them according to their characteristic fragment ions and mobility drift times. Therefore, a rational assignment of isomeric structures in many phenolic secondary metabolites based on the ion mobility data might be useful in mass spectrometry-based structure analysis in the future.

  3. [Development of a chemical ionization time-of-flight mass spectrometer for continuous measurements of atmospheric hydroxyl radical].

    PubMed

    Dou, Jian; Hua, Lei; Hou, Ke-Yong; Jiang, Lei; Xie, Yuan-Yuan; Zhao, Wu-Duo; Chen, Ping; Wang, Wei-Guo; Di, Tian; Li, Hai-Yang

    2014-05-01

    A home-made chemical ionization time-of-flight mass spectrometer (TOFMS) has been developed for continuous measurements of atmospheric hydroxyl radical. Based on the atmospheric pressure chemical ionization technique, an ionization source with orthogonal dual tube structure was adopted in the instrument, which minimized the interference between the reagent gas ionization and the titration reaction. A 63Ni radioactive source was fixed inside one of the orthogonal tubes to generate reactant ion of NO(-)(3) from HNO3 vapor. Hydroxyl radical was first titrated by excess SO2 to form equivalent concentrations of H2SO4 in the other orthogonal tube, and then reacted with NO(-)(3) ions in the chemical ionization chamber, leading to HSO(-)(4) formation. The concentration of atmospheric hydroxyl radical can be directly calculated by measuring the intensities of the HSOj product ions and the NO(-)(3) reactant ions. The analytical capability of the instrument was demonstrated by measuring hydroxyl radical in laboratory air, and the concentration of the hydroxyl radical in the investigated air was calculated to be 1.6 x 106 molecules*cm ', based on 5 seconds integration. The results have shown that the instrument is competent for in situ continuous measurements of atmospheric trace radical.

  4. Dissociation of 1,1,1-trifluoroethane behind reflected shock waves :shock tube/time-of-flight mass spectrometry experiments.

    SciTech Connect

    Giri, B. R.; Tranter, R. S.; Chemistry

    2007-01-01

    The dissociation of 1,1,1,-trifluoroethane, a potential non-RRKM reaction, has been studied at 600 and 1200 Torr and high temperatures (1500-1840 K) using a new shock tube/time-of-flight mass spectrometer (ST/TOF-MS). These data obtained by an independent method are in good agreement with the laser schlieren, LS, experiments of Kiefer et al. [J. Phys. Chem. A 2004, 108, 2443-2450] and extend the range of that experimental dataset. The data have been simulated by both standard RRKM calculations and the non-RRKM model reported by Kiefer et al. but with <{Delta}E{sub down}> = 750 cm{sup -1}. Both the RRKM and non-RRKM calculations provide equally good fits to the ST/TOF-MS data. Neither model simulates the combined ST/TOF-MS and LS datasets particularly well. However, the non-RRKM model predicts a pressure dependency closer to that observed in the experiments than the RRKM model.

  5. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry applied to virus identification

    PubMed Central

    Calderaro, Adriana; Arcangeletti, Maria-Cristina; Rodighiero, Isabella; Buttrini, Mirko; Gorrini, Chiara; Motta, Federica; Germini, Diego; Medici, Maria-Cristina; Chezzi, Carlo; De Conto, Flora

    2014-01-01

    Virus detection and/or identification traditionally rely on methods based on cell culture, electron microscopy and antigen or nucleic acid detection. These techniques are good, but often expensive and/or time-consuming; furthermore, they not always lead to virus identification at the species and/or type level. In this study, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was tested as an innovative tool to identify human polioviruses and to identify specific viral protein biomarkers in infected cells. The results revealed MALDI-TOF MS to be an effective and inexpensive tool for the identification of the three poliovirus serotypes. The method was firstly applied to Sabin reference strains, and then to isolates from different clinical samples, highlighting its value as a time-saving, sensitive and specific technique when compared to the gold standard neutralization assay and casting new light on its possible application to virus detection and/or identification. PMID:25354905

  6. Profiling the metabolism of astragaloside IV by ultra performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry.

    PubMed

    Cheng, Xu-Dong; Wei, Ming-Gang

    2014-01-01

    Astragaloside IV is a compound isolated from the Traditional Chinese Medicine Astragalus membranaceus, that has been reported to have bioactivities against cardiovascular disease and kidney disease. There is limited information on the metabolism of astragaloside IV, which impedes comprehension of its biological actions and pharmacology. In the present study, an ultra-performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS)-based approach was developed to profile the metabolites of astragaloside IV in rat plasma, bile, urine and feces samples. Twenty-two major metabolites were detected. The major components found in plasma, bile, urine and feces included the parent chemical and phases I and II metabolites. The major metabolic reactions of astragaloside IV were hydrolysis, glucuronidation, sulfation and dehydrogenation. These results will help to improve understanding the metabolism and reveal the biotransformation profiling of astragaloside IV in vivo. The metabolic information obtained from our study will guide studies into the pharmacological activity and clinical safety of astragaloside IV. PMID:25407723

  7. Metabolite analysis of toosendanin by an ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry technique.

    PubMed

    Wu, Jian-Lin; Leung, Elaine Lai-Han; Zhou, Hua; Liu, Liang; Li, Na

    2013-01-01

    Toosendanin is the major bioactive component of Melia toosendan Sieb. et Zucc., which is traditionally used for treatment of abdominal pain and as an insecticide. Previous studies reported that toosendanin possesses hepatotoxicity, but the mechanism remains unknown. Its bioavailability in rats is low, which indicates the hepatotoxicity might be induced by its metabolites. In this connection, in the current study, we examined the metabolites obtained by incubating toosendanin with human live microsomes, and then six of these metabolites (M1-M6) were identified for the first time by ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF/MS). Further analysis on the MS spectra showed M1, M2, and M3 are oxidative products and M6 is a dehydrogenation product, while M4 and M5 are oxidative and dehydrogenation products of toosendanin. Moreover, their possible structures were deduced from the MS/MS spectral features. Quantitative analysis demonstrated that M1-M5 levels rapidly increased and reached a plateau at 30 min, while M6 rapidly reached a maximal level at 20 min and then decreased slowly afterwards. These findings have provided valuable data not only for understanding the metabolic fate of toosendanin in liver microsomes, but also for elucidating the possible molecular mechanism of its hepatotoxicity. PMID:24084018

  8. Untargeted metabolomic analysis using liquid chromatography quadrupole time-of-flight mass spectrometry for non-volatile profiling of wines.

    PubMed

    Arbulu, M; Sampedro, M C; Gómez-Caballero, A; Goicolea, M A; Barrio, R J

    2015-02-01

    The current study presents a method for comprehensive untargeted metabolomic fingerprinting of the non-volatile profile of the Graciano Vitis vinifera wine variety, using liquid chromatography/electrospray ionization time of flight mass spectrometry (LC-ESI-QTOF). Pre-treatment of samples, chromatographic columns, mobile phases, elution gradients and ionization sources, were evaluated for the extraction of the maximum number of metabolites in red wine. Putative compounds were extracted from the raw data using the extraction algorithm, molecular feature extractor (MFE). For the metabolite identification the WinMet database was designed based on electronic databases and literature research and includes only the putative metabolites reported to be present in oenological matrices. The results from WinMet were compared with those in the METLIN database to evaluate how much the databases overlap for performing identifications. The reproducibility of the analysis was assessed using manual processing following replicate injections of Vitis vinifera cv. Graciano wine spiked with external standards. In the present work, 411 different metabolites in Graciano Vitis vinifera red wine were identified, including primary wine metabolites such as sugars (4%), amino acids (23%), biogenic amines (4%), fatty acids (2%), and organic acids (32%) and secondary metabolites such as phenols (27%) and esters (8%). Significant differences between varieties Tempranillo and Graciano were related to the presence of fifteen specific compounds.

  9. Action spectroscopy of SrCl{sup +} using an integrated ion trap time-of-flight mass spectrometer

    SciTech Connect

    Puri, Prateek Schowalter, Steven J.; Hudson, Eric R.; Kotochigova, Svetlana; Petrov, Alexander

    2014-07-07

    The photodissociation cross-section of SrCl{sup +} is measured in the spectral range of 36 000–46 000 cm{sup −1} using a modular time-of-flight mass spectrometer (TOF-MS). By irradiating a sample of trapped SrCl{sup +} molecular ions with a pulsed dye laser, X{sup 1}Σ{sup +} state molecular ions are electronically excited to the repulsive wall of the A{sup 1}Π state, resulting in dissociation. Using the TOF-MS, the product fragments are detected and the photodissociation cross-section is determined for a broad range of photon energies. Detailed ab initio calculations of the SrCl{sup +} molecular potentials and spectroscopic constants are also performed and are found to be in good agreement with experiment. The spectroscopic constants for SrCl{sup +} are also compared to those of another alkaline earth halogen, BaCl{sup +}, in order to highlight structural differences between the two molecular ions. This work represents the first spectroscopy and ab initio calculations of SrCl{sup +}.

  10. Identification of senkyunolide I metabolites in rats using ultra performance liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry.

    PubMed

    Xiong, Yao-kun; Lin, Xiao; Liang, Shuang; Hong, Yan-long; Shen, Lan; Feng, Yi

    2013-01-01

    Ligusticum chuanxiong Hort. (Umbelliferae) has been widely prescribed to treat cardiovascular disease in China for centuries. Senkyunolide I is one of the major bioactive components in L. chuanxiong, which shows pharmacological activities against migraines and oxidative damage. In this paper, ultra performance liquid chromatography/quadrupole-time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS) was applied for the rapid analysis of senkyunolide I metabolites in rats after its intravenous administration. The non-metabolized parent compound and eighteen metabolites from drug-treated samples in rat plasma, urine and bile were identified. Our analysis indicated that methylation, hydration, epoxidation, glucuronidation and glutathione conjugation were the major pathways of senkyunolide I metabolism in vivo. This study provides important information regarding the metabolism of senkyunolide I, which will be helpful for understanding its mechanism of action. Furthermore, this work demonstrates the potential of using UPLC/Q-TOF-MS for the rapid and reliable characterization of the metabolites of natural products. PMID:23666254

  11. Evaluating the Aging of Multiple Emulsions Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry.

    PubMed

    Tsuda, Yukihiro; Uchimura, Tomohiro

    2016-01-01

    Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry was applied to measurements of multiple emulsions with no pretreatment; a method for the quantitative evaluation of aging was proposed. We prepared water-in-oil-in-water (W/O/W) multiple emulsions containing toluene and m-phenylenediamine. The samples were measured immediately following both preparation and after having been stirred for 24 h. Time profiles of the peak areas for each analyte species were obtained, and several intense spikes for toluene could be detected from each sample after stirring, which suggests that the concentration of toluene in the middle phase had increased during stirring. On the other hand, in the case of a W/O/W multiple emulsion containing phenol and m-phenylenediamine, spikes for m-phenylenediamine, rather than phenol, were detected after stirring. In the present study, the time-profile data were converted into a scatter plot in order to quantitatively evaluate the aging. As a result, the ratio of the plots where strong signal intensities of toluene were detected increased from 8.4% before stirring to 33.2% after stirring for 24 h. The present method could be a powerful tool for evaluating multiple emulsions, such as studies on the kinetics of the encapsulation and release of active ingredients. PMID:27396662

  12. Secondary ionization of chemical warfare agent simulants: atmospheric pressure ion mobility time-of-flight mass spectrometry.

    PubMed

    Steiner, Wes E; Clowers, Brian H; Haigh, Paul E; Hill, Herbert H

    2003-11-15

    For the first time, the use of a traditional ionization source for ion mobility spectrometry (radioactive nickel ((63)Ni) beta emission ionization) and three alternative ionization sources (electrospray ionization (ESI), secondary electrospray ionization (SESI), and electrical discharge (corona) ionization (CI)) were employed with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer (IM(tof)MS) to detect chemical warfare agent (CWA) simulants from both aqueous- and gas-phase samples. For liquid-phase samples, ESI was used as the sample introduction and ionization method. For the secondary ionization (SESI, CI, and traditional (63)Ni ionization) of vapor-phase samples, two modes of sample volatilization (heated capillary and thermal desorption chamber) were investigated. Simulant reference materials, which closely mimic the characteristic chemical structures of CWA as defined and described by Schedule 1, 2, or 3 of the Chemical Warfare Convention treaty verification, were used in this study. A mixture of four G/V-type nerve simulants (dimethyl methylphosphonate, pinacolyl methylphosphonate, diethyl phosphoramidate, and 2-(butylamino)ethanethiol) and one S-type vesicant simulant (2-chloroethyl ethyl sulfide) were found in each case (sample ionization and introduction methods) to be clearly resolved using the IM(tof)MS method. In many cases, reduced mobility constants (K(o)) were determined for the first time. Ion mobility drift times, flight times, relative signal intensities, and fragmentation product signatures for each of the CWA simulants are reported for each of the methods investigated. PMID:14615983

  13. Ultra-high-performance liquid chromatography-Time-of-flight high resolution mass spectrometry to quantify acidic drugs in wastewater.

    PubMed

    Becerra-Herrera, Mercedes; Honda, Luis; Richter, Pablo

    2015-12-01

    A novel analytical approach involving an improved rotating-disk sorptive extraction (RDSE) procedure and ultra-high-performance liquid chromatography (UHPLC) coupled to an ultraspray electrospray ionization source (UESI) and time-of-flight mass spectrometry (TOF/MS), in trap mode, was developed to identify and quantify four non-steroidal anti-inflammatory drugs (NSAIDs) (naproxen, ibuprofen, ketoprofen and diclofenac) and two anti-cholesterol drugs (ACDs) (clofibric acid and gemfibrozil) that are widely used and typically found in water samples. The method reduced the amount of both sample and reagents used and also the time required for the whole analysis, resulting in a reliable and green analytical strategy. The analytical eco-scale was calculated, showing that this methodology is an excellent green analysis, increasing its ecological worth. The detection limits (LOD) and precision (%RSD) were lower than 90ng/L and 10%, respectively. Matrix effects and recoveries were studied using samples from the influent of a wastewater treatment plant (WWTP). All the compounds exhibited suppression of their signals due to matrix effects, and the recoveries were approximately 100%. The applicability and reliability of this methodology were confirmed through the analysis of influent and effluent samples from a WWTP in Santiago, Chile, obtaining concentrations ranging from 1.1 to 20.5μg/L and from 0.5 to 8.6μg/L, respectively. PMID:26559617

  14. Identification of a variety of Staphylococcus species by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Dubois, Damien; Leyssene, David; Chacornac, Jean Paul; Kostrzewa, Markus; Schmit, Pierre Olivier; Talon, Régine; Bonnet, Richard; Delmas, Julien

    2010-03-01

    Whole-cell fingerprinting by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) in combination with a dedicated bioinformatic software tool (MALDI Biotyper 2.0) was used to identify 152 staphylococcal strains corresponding to 22 staphylococcal species. Spectra of the 152 isolates, previously identified at the species level using a sodA gene-based oligonucleotide array, were analyzed against the main spectra of 3,030 microorganisms. A total of 151 strains out of 152 (99.3%) were correctly identified at the species level; only one strain was identified at the genus level. The MALDI-TOF MS method revealed different clonal lineages of Staphylococcus epidermidis that were of either human or environmental origin, which suggests that the MALDI-TOF MS method could be useful in the profiling of staphylococcal strains. The topology of the dendrogram generated by the MALDI Biotyper 2.0 software from the spectra of 120 Staphylococcus reference strains (representing 36 species) was in general agreement with that inferred from the 16S rRNA gene-based analysis. Our findings indicate that the MALDI-TOF MS technology, associated with a broad-spectrum reference database, is an effective tool for the swift and reliable identification of Staphylococci.

  15. Analysis of synthetic canine training aids by comprehensive two-dimensional gas chromatography-time of flight mass spectrometry.

    PubMed

    Stadler, Sonja; Stefanuto, Pierre-Hugues; Byer, Jonathan D; Brokl, Michał; Forbes, Shari; Focant, Jean-François

    2012-09-14

    Cadaver dogs are trained on a variety of materials, including artificial or pseudo scents. The chemical components of commercially available pseudo scents are not known, so their accuracy as a decomposition odour mimic and their effectiveness as a canine training aid have not been evaluated. Two pseudo scents that are commercially available and used for training cadaver dogs were analysed using comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC×GC-TOFMS). The two formulations were determined to be simplistic in their composition, compared to real cadaveric volatile organic compound (VOC) mixtures, with only a few major components. The enhanced GC×GC-TOFMS peak capacity was nevertheless useful to discriminate less intense peaks from large overloaded peaks. The availability of both dimension retention times combined with the peak finding and deconvolution algorithm, enabled the chemical characterization of the two formulations. Additionally, high resolution (HR) TOFMS was used to extract molecular formulae and confirm identities of analytes. The seven compounds identified by this work have not been reported previously as volatile products of decomposition, indicating that these pseudo scents are not to be considered as an accurate representation of cadaveric decomposition odour. Further research on the olfaction of scent detection canines and the chemical composition of their target odourants needs to be conducted to develop improved canine training aids.

  16. Optimization of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Analysis for Bacterial Identification

    PubMed Central

    Khot, Prasanna D.; Couturier, Marc R.; Wilson, Andrew; Croft, Ann

    2012-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a relatively new addition to the clinical microbiology laboratory. The performance of the MALDI Biotyper system (Bruker Daltonics) was compared to those of phenotypic and genotypic identification methods for 690 routine and referred clinical isolates representing 102 genera and 225 unique species. We systematically compared direct-smear and extraction methods on a taxonomically diverse collection of isolates. The optimal score thresholds for bacterial identification were determined, and an approach to address multiple divergent results above these thresholds was evaluated. Analysis of identification scores revealed optimal species- and genus-level identification thresholds of 1.9 and 1.7, with 91.9% and 97.0% of isolates correctly identified to species and genus levels, respectively. Not surprisingly, routinely encountered isolates showed higher concordance than did uncommon isolates. The extraction method yielded higher scores than the direct-smear method for 78.3% of isolates. Incorrect species were reported in the top 10 results for 19.4% of isolates, and although there was no obvious cutoff to eliminate all of these ambiguities, a 10% score differential between the top match and additional species may be useful to limit the need for additional testing to reach single-species-level identifications. PMID:22993178

  17. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    PubMed

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes.

  18. Direct matrix-assisted laser desorption ionization time-of-flight mass spectrometry improves appropriateness of antibiotic treatment of bacteremia.

    PubMed

    Vlek, Anne L M; Bonten, Marc J M; Boel, C H Edwin

    2012-01-01

    Matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows the identification of microorganisms directly from positive blood culture broths. Use of the MALDI-TOF MS for rapid identification of microorganisms from blood culture broths can reduce the turnaround time to identification and may lead to earlier appropriate treatment of bacteremia. During February and April 2010, direct MALDI-TOF MS was routinely performed on all positive blood cultures. During December 2009 and March 2010 no direct MALDI-TOF MS was used. Information on antibiotic therapy was collected from the hospital and intensive care units' information systems from all positive blood cultures during the study period. In total, 253 episodes of bacteremia were included of which 89 during the intervention period and 164 during the control period. Direct performance of MALDI-TOF MS on positive blood culture broths reduced the time till species identification by 28.8-h and was associated with an 11.3% increase in the proportion of patients receiving appropriate antibiotic treatment 24 hours after blood culture positivity (64.0% in the control period versus 75.3% in the intervention period (p0.01)). Routine implementation of this technique increased the proportion of patients on adequate antimicrobial treatment within 24 hours.

  19. Rapid Microcystin Determination Using a Paper Spray Ionization Method with a Time-of-Flight Mass Spectrometry System.

    PubMed

    Zhu, Xiaoqiang; Huang, Zhengxu; Gao, Wei; Li, Xue; Li, Lei; Zhu, Hui; Mo, Ting; Huang, Bao; Zhou, Zhen

    2016-07-13

    The eutrophication of surface water sources and climate changes have resulted in an annual explosion of cyanobacterial blooms in many irrigating and drinking water resources. To decrease health risks to the public, a rapid real time method for the synchronous determination of two usually harmful microcystins (MC-RR and MC-LR) in environmental water samples was built by employing a paper spray ionization method coupled with a time-of-flight mass spectrometer system. With this approach, direct analysis of microcystin mixtures without sample preparation has been achieved. Rapid detection was performed, simulating the release process of microcystins in reservoir water samples, and the routine detection frequency was every three minutes. The identification time of microcystins was reduced from several hours to a few minutes. The limit of detection is 1 μg/L, and the limit of quantitation is 3 μg/L. This method displays the ability for carrying out rapid, direct, and high-throughput experiments for determination of microcystins, and it would be of significant interest for environmental and food safety applications.

  20. Ultra-high-performance liquid chromatography-Time-of-flight high resolution mass spectrometry to quantify acidic drugs in wastewater.

    PubMed

    Becerra-Herrera, Mercedes; Honda, Luis; Richter, Pablo

    2015-12-01

    A novel analytical approach involving an improved rotating-disk sorptive extraction (RDSE) procedure and ultra-high-performance liquid chromatography (UHPLC) coupled to an ultraspray electrospray ionization source (UESI) and time-of-flight mass spectrometry (TOF/MS), in trap mode, was developed to identify and quantify four non-steroidal anti-inflammatory drugs (NSAIDs) (naproxen, ibuprofen, ketoprofen and diclofenac) and two anti-cholesterol drugs (ACDs) (clofibric acid and gemfibrozil) that are widely used and typically found in water samples. The method reduced the amount of both sample and reagents used and also the time required for the whole analysis, resulting in a reliable and green analytical strategy. The analytical eco-scale was calculated, showing that this methodology is an excellent green analysis, increasing its ecological worth. The detection limits (LOD) and precision (%RSD) were lower than 90ng/L and 10%, respectively. Matrix effects and recoveries were studied using samples from the influent of a wastewater treatment plant (WWTP). All the compounds exhibited suppression of their signals due to matrix effects, and the recoveries were approximately 100%. The applicability and reliability of this methodology were confirmed through the analysis of influent and effluent samples from a WWTP in Santiago, Chile, obtaining concentrations ranging from 1.1 to 20.5μg/L and from 0.5 to 8.6μg/L, respectively.

  1. Enhancing Secondary Ion Yields in Time of Flight-Secondary Ion Mass Spectrometry Using Water Cluster Primary Beams

    PubMed Central

    2013-01-01

    Low secondary ion yields from organic and biological molecules are the principal limitation on the future exploitation of time of flight-secondary ion mass spectrometry (TOF-SIMS) as a surface and materials analysis technique. On the basis of the hypothesis that increasing the density of water related fragments in the ion impact zone would enhance proton mediated reactions, a prototype water cluster ion beam has been developed using supersonic jet expansion methodologies that enable ion yields using a 10 keV (H2O)1000+ beam to be compared with those obtained using a 10 keV Ar1000+ beam. The ion yields from four standard compounds, arginine, haloperidol, DPPC, and angiotensin II, have been measured under static+ and high ion dose conditions. Ion yield enhancements relative to the argon beam on the order of 10 or more have been observed for all the compounds such that the molecular ion yield per a 1 μm pixel can be as high as 20, relative to 0.05 under an argon beam. The water beam has also been shown to partially lift the matrix effect in a 1:10 mixture of haloperidol and dipalmitoylphosphatidylcholine (DPPC) that suppresses the haloperidol signal. These results provide encouragement that further developments of the water cluster beam to higher energies and larger cluster sizes will provide the ion yield enhancements necessary for the future development of TOF-SIMS. PMID:23718847

  2. High throughput screening of genetic polymorphisms by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    PubMed

    Corona, Giuseppe; Toffoli, Giuseppe

    2004-12-01

    In the post genomic era, the screening of many different genetic polymorphisms in large populations represents a major goal that will facilitate the understanding of individual genetic variability in the development of multi factor diseases and in drug response and toxicities. The increasing interest in these pathogenetic and pharmacogenomic studies by both academic and pharmaceutical industry researchers has increased the demand for broad genome association studies. This demand has produced a boom in the development of new and robust high throughput screening methods for genotype analysis. Matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents an emerging and powerful technique for DNA analysis because of its high speed, accuracy, no label requirement, and cost-effectiveness. So far, many MALDI-TOF MS approaches have been developed for rapid screening of single nucleotide polymorphisms (SNPs), variable sequences repeat, epigenotype analysis, quantitative allele studies, and for the discovery of new genetic polymorphisms. The more established methods are based on single base primer extension and minisequencing implemented with new chemical features to overcome the limitations associated with DNA analysis using MALDI-TOF MS. These new promising methods of genotyping include both photochemical and other different chemical and enzyme cleavage strategies that facilitate sample automation and MS analysis for both real-time genotyping and resequencing screening. In this review, we analyze and discuss in depth the advantages and the limitations of the more recent developments in MALDI-TOF MS analysis for large-scale genomic studies applications.

  3. Rapid Microcystin Determination Using a Paper Spray Ionization Method with a Time-of-Flight Mass Spectrometry System.

    PubMed

    Zhu, Xiaoqiang; Huang, Zhengxu; Gao, Wei; Li, Xue; Li, Lei; Zhu, Hui; Mo, Ting; Huang, Bao; Zhou, Zhen

    2016-07-13

    The eutrophication of surface water sources and climate changes have resulted in an annual explosion of cyanobacterial blooms in many irrigating and drinking water resources. To decrease health risks to the public, a rapid real time method for the synchronous determination of two usually harmful microcystins (MC-RR and MC-LR) in environmental water samples was built by employing a paper spray ionization method coupled with a time-of-flight mass spectrometer system. With this approach, direct analysis of microcystin mixtures without sample preparation has been achieved. Rapid detection was performed, simulating the release process of microcystins in reservoir water samples, and the routine detection frequency was every three minutes. The identification time of microcystins was reduced from several hours to a few minutes. The limit of detection is 1 μg/L, and the limit of quantitation is 3 μg/L. This method displays the ability for carrying out rapid, direct, and high-throughput experiments for determination of microcystins, and it would be of significant interest for environmental and food safety applications. PMID:27345366

  4. Electrospray ionization quadrupole time-of-flight tandem mass spectrometric analysis of hexamethylenediamine-modified maltodextrin and dextran.

    PubMed

    Sisu, Eugen; Bosker, Wouter T E; Norde, Willem; Slaghek, Ted M; Timmermans, Johan W; Peter-Katalinić, Jasna; Cohen-Stuart, Martien A; Zamfir, Alina D

    2006-01-01

    A combined methodology for obtaining at the preparative scale and characterization by nanoelectrospray ionization (nanoESI) quadrupole time-of-flight (QTOF) mass spectrometry (MS) and tandem MS (MS/MS) of linear polysaccharides modified at the reducing end is presented. Two polydisperse maltodextrins (1000 and 3000 Da) and a high molecular weight polydisperse dextran (6000 Da) were coupled with hexamethylenediamine (HMD). The coupling products were analyzed by nanoESI-QTOF-MS in the positive ion mode and MS/MS using collision-induced dissociation (CID) at low energies. In the HMD-M1000 mixture, the polysaccharide chains containing from 2 to 8 Glc residues were detected, while in HMD-M3000 we identified a complete series of chains containing from 8 to 21 Glc moieties. The employed ESI conditions enhanced the detection of chains with up to 46 Glc residues in the HMD-D6000 sample. By optimized MS/MS, HMD-modified polysaccharides of 3, 4, 5, 12 and 46 degrees of polymerization yielded product ion spectra exhibiting the whole set of Y- and B-fragment ions. The MS structural data were obtained within a few minutes of signal acquisition, with a sample consumption situating the analysis sensitivity in the picomolar range.

  5. Validation of Direct Analysis Real Time source/Time-of-Flight Mass Spectrometry for organophosphate quantitation on wafer surface.

    PubMed

    Hayeck, Nathalie; Ravier, Sylvain; Gemayel, Rachel; Gligorovski, Sasho; Poulet, Irène; Maalouly, Jacqueline; Wortham, Henri

    2015-11-01

    Microelectronic wafers are exposed to airborne molecular contamination (AMC) during the fabrication process of microelectronic components. The organophosphate compounds belonging to the dopant group are one of the most harmful groups. Once adsorbed on the wafer surface these compounds hardly desorb and could diffuse in the bulk of the wafer and invert the wafer from p-type to n-type. The presence of these compounds on wafer surface could have electrical effect on the microelectronic components. For these reasons, it is of importance to control the amount of these compounds on the surface of the wafer. As a result, a fast quantitative and qualitative analytical method, nondestructive for the wafers, is needed to be able to adjust the process and avoid the loss of an important quantity of processed wafers due to the contamination by organophosphate compounds. Here we developed and validated an analytical method for the determination of organic compounds adsorbed on the surface of microelectronic wafers using the Direct Analysis in Real Time-Time of Flight-Mass Spectrometry (DART-ToF-MS) system. Specifically, the developed methodology concerns the organophosphate group.

  6. Characterization of Gas-Phase Organics Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry: Cooking Emissions.

    PubMed

    Klein, Felix; Platt, Stephen M; Farren, Naomi J; Detournay, Anais; Bruns, Emily A; Bozzetti, Carlo; Daellenbach, Kaspar R; Kilic, Dogushan; Kumar, Nivedita K; Pieber, Simone M; Slowik, Jay G; Temime-Roussel, Brice; Marchand, Nicolas; Hamilton, Jacqueline F; Baltensperger, Urs; Prévôt, André S H; El Haddad, Imad

    2016-02-01

    Cooking processes produce gaseous and particle emissions that are potentially deleterious to human health. Using a highly controlled experimental setup involving a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS), we investigate the emission factors and the detailed chemical composition of gas phase emissions from a broad variety of cooking styles and techniques. A total of 95 experiments were conducted to characterize nonmethane organic gas (NMOG) emissions from boiling, charbroiling, shallow frying, and deep frying of various vegetables and meats, as well as emissions from vegetable oils heated to different temperatures. Emissions from boiling vegetables are dominated by methanol. Significant amounts of dimethyl sulfide are emitted from cruciferous vegetables. Emissions from shallow frying, deep frying and charbroiling are dominated by aldehydes of differing relative composition depending on the oil used. We show that the emission factors of some aldehydes are particularly large which may result in considerable negative impacts on human health in indoor environments. The suitability of some of the aldehydes as tracers for the identification of cooking emissions in ambient air is discussed. PMID:26766423

  7. Monitoring protein glycation by electrospray ionization (ESI) quadrupole time-of-flight (Q-TOF) mass spectrometer.

    PubMed

    Akıllıoğlu, H Gül; Çelikbıçak, Ömür; Salih, Bekir; Gökmen, Vural

    2017-02-15

    In this study electrospray ionization quadrupole time-of-flight (ESI-Q-TOF) mass spectrometry was used to investigate protein glycation. The glycated species of cytochrome C, lysozyme, and β-casein formed during glycation with d-glucose were identified and monitored in binary systems heated at 70°C under dry and aqueous conditions. Cytochrome C had multiple charges in non-glycated state, primarily changing from +13 to +17 positive charges, whereas β-casein had charge states up to +30. Upon heating with glucose at 70°C in aqueous state, attachment of one glucose molecule onto proteins was observed in each charge state. However, heating in dry state caused much more glucose attachment, leading to the formation of multiple glycoforms of proteins. By using ESI-QTOF-MS technique, formation of glycated cytochrome C containing up to 12 glucose moieties were observed, while glycated species containing 6 and 8 glucose moieties were observed for lysozyme and β-casein, respectively in various heating conditions. PMID:27664609

  8. Time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy analyses of Bixa orellana seeds.

    PubMed

    Felicissimo, Marcella P; Bittencourt, Carla; Houssiau, Laurent; Pireaux, Jean-Jacques

    2004-04-01

    Three different experiments were performed in order to obtain the major carotenoid composition of the natural colorant annatto (E160b) through ToF-SIMS (time-of-flight secondary ion mass spectrometry) and XPS (X-ray photoelectron spectroscopy) analyses. In the first experiment, Bixa orellana seeds aril as well as its interior part were analyzed. The analysis of the seeds aril by ToF-SIMS gives the colorant fingerprint without any sample treatment, showing the presence of bixin and its characteristic fragments. The analysis performed in the interior part of the seeds indicates the presence of Fe. The second set of measurements was conducted on the seeds organic extract right after extraction revealing the same components observed by in situ measurement. A third set of measurements was performed aiming to determine the reason for the organic extract color shift observed after 3 months of exposure to ambient light at room temperature. In this case, it was possible to evidence the degradation of bixin by the loss of xylene molecules through ToF-SIMS and the probable carotenoid oxidation based on the C1s XPS spectrum of the degraded extract. PMID:15053514

  9. Depth profile analysis of amorphous silicon thin film solar cells by pulsed radiofrequency glow discharge time of flight mass spectrometry.

    PubMed

    Alvarez-Toral, Aitor; Sanchez, Pascal; Menéndez, Armando; Pereiro, Rosario; Sanz-Medel, Alfredo; Fernández, Beatriz

    2015-02-01

    Among the different solar cell technologies, amorphous silicon (a-Si:H) thin film solar cells (TFSCs) are today very promising and, so, TFSCs analytical characterization for quality control issues is increasingly demanding. In this line, depth profile analysis of a-Si:H TFSCs on steel substrate has been investigated by using pulsed radiofrequency glow discharge-time of flight mass spectrometry (rf-PGD-TOFMS). First, to discriminate potential polyatomic interferences for several analytes (e.g., (28)Si(+), (31)P(+), and (16)O(+)) appropriate time positions along the GD pulse profile were selected. A multi-matrix calibration approach, using homogeneous certified reference materials without hydrogen as well as coated laboratory-made standards containing hydrogen, was employed for the methodological calibration. Different calibration strategies (in terms of time interval selection on the pulse profile within the afterglow region) have been compared, searching for optimal calibration graphs correlation. Results showed that reliable and fast quantitative depth profile analysis of a-Si:H TFSCs by rf-PGD-TOFMS can be achieved. PMID:25404156

  10. Identification of phlebotomine sand flies (Diptera: Psychodidae) by matrix-assisted laser desorption/ionization time of flight mass spectrometry

    PubMed Central

    2014-01-01

    Background Phlebotomine sand flies are incriminated in the transmission of several human and veterinary pathogens. To elucidate their role as vectors, proper species identification is crucial. Since traditional morphological determination is based on minute and often dubious characteristics on their head and genitalia, which require certain expertise and may be damaged in the field-collected material, there is a demand for rapid, simple and cost-effective molecular approaches. Methods Six laboratory-reared colonies of phlebotomine sand flies belonging to five species and four subgenera (Phlebotomus, Paraphlebotomus, Larroussius, Adlerius) were used to evaluate the discriminatory power of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Various storage conditions and treatments, including the homogenization in either distilled water or given concentrations of formic acid, were tested on samples of both sexes. Results Specimens of all five analysed sand fly species produced informative, reproducible and species-specific protein spectra that enabled their conclusive species identification. The method also distinguished between two P. sergenti colonies originating from different geographical localities. Protein profiles within a species were similar for specimens of both sexes. Tested conditions of specimen storage and sample preparation give ground to a standard protocol that is generally applicable on analyzed sand fly specimens. Conclusions Species identification of sand flies by MALDI-TOF MS is feasible and represents a novel promising tool to improve biological and epidemiological studies on these medically important insects. PMID:24423215

  11. Top-down N-terminal sequencing of Immunoglobulin subunits with electrospray ionization time of flight mass spectrometry.

    PubMed

    Ren, Da; Pipes, Gary D; Hambly, David; Bondarenko, Pavel V; Treuheit, Michael J; Gadgil, Himanshu S

    2009-01-01

    An N-terminal top-down sequencing approach was developed for IgG characterization, using high-resolution HPLC separation and collisionally activated dissociation (CAD) on a single-stage LCT Premier time of flight (TOF) mass spectrometer. Fragmentation of the IgG chains on the LCT Premier was optimized by varying the ion guide voltage values. Ion guide 1 voltage had the most significant effect on the fragmentation of the IgG chains. An ion guide 1 voltage value of 100 V was found to be optimum for the N-terminal fragmentation of IgG heavy and light chains, which are approximately 50 and 25 kDa, respectively. The most prominent ion series in this CAD experiment was the terminal b-ion series which allows N-terminal sequencing. Using this technique, we were able to confirm the sequence of up to seven N-terminal residues. Applications of this method for the identification of N-terminal pyroglutamic acid formation will be discussed. The method described could be used as a high-throughput method for the rapid N-terminal sequencing of IgG chains and for the detection of chemical modifications in the terminal residues.

  12. Sequence analysis of phosphorothioate oligonucleotides via matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    PubMed

    Schuette, J M; Pieles, U; Maleknia, S D; Srivatsa, G S; Cole, D L; Moser, H E; Afeyan, N B

    1995-09-01

    Modification of the natural phosphodiester backbone of deoxyribooligonucleotides can impart increased biostability via nuclease resistance. Further, uniform incorporation of phosphorothioate linkages renders oligonucleotides highly resistant to reagents traditionally used in sequencing reactions. As a consequence, analytical tests crucial for establishing the identity of such oligonucleotide drugs are less informative. To circumvent this problem, chemical oxidation has been employed for converting the phosphorothioate to the uniform phosphodiester, thereby facilitating enzymatic degradation. Following oxidation, exonucleases which sequentially cleave individual bases from the 3' or 5' terminus of the oligonucleotide or base-specific cleavage chemicals were used to facilitate sequence identification of the oligonucleotide. Matrix-assisted laser desorption ionization-time-of-flight/mass spectrometry (MALDI-TOF/MS), previously used to sequence natural phosphodiester DNA, was then used to sequence the chemically oxidized phosphorothioate. Sequential enzymatic cleavage of desulphurized phosphorothioates in combination with MALDI analysis not only provides a viable alternative to radiolabeling as used in conventional sequencing approaches (e.g. Maxam-Gilbert), but also enables rapid sequencing of phosphorothioate oligonucleotides, for routine drug analysis. PMID:8562591

  13. High-throughput intracellular pteridinic profiling by liquid chromatography-quadrupole time-of-flight mass spectrometry.

    PubMed

    Burton, Casey; Weng, Rui; Yang, Li; Bai, Yu; Liu, Huwei; Ma, Yinfa

    2015-01-01

    Pteridines are a diverse family of endogenous metabolites that may serve as useful diagnostic biomarkers for disease. While many preparative and analytical techniques have been described for analysis of selected pteridines in biological fluids, broad intracellular pteridine detection remains a significant analytical challenge. In this study, a novel, specific and sensitive extraction and high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS) method was developed to simultaneously quantify seven intracellular pteridines and monitor 18 additional, naturally-occurring intracellular pteridines. The newly developed method was validated through evaluation of spiked recoveries (84.5-109.4%), reproducibility (2.1-5.4% RSD), method detection limits (0.1-3.0 μg L(-1)) and limits of quantitation (0.1-1 μg L(-1)), and finally application to non-small cell lung cancer A549 cells. Twenty-three pteridine derivatives were successfully detected from cell lysates with an average RSD of 12% among culture replicates. Quantified intracellular pteridine levels ranged from 1 to 1000 nM in good agreement with previous studies. Finally, this technique may be applied to cellular studies to generate new biological hypotheses concerning pteridine physiological and pathological functions as well as to discovery new pteridine-based biomarkers.

  14. A simple algorithm improves mass accuracy to 50-100 ppm for delayed extraction linear matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Hack, Christopher A; Benner, W Henry

    2002-01-01

    A simple mathematical technique for improving mass calibration accuracy of linear delayed extraction matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (DE MALDI-TOFMS) spectra is presented. The method involves fitting a parabola to a plot of Delta(m) vs. mass data where Delta(m) is the difference between the theoretical mass of calibrants and the mass obtained from a linear relationship between the square root of m/z and ion time of flight. The quadratic equation that describes the parabola is then used to correct the mass of unknowns by subtracting the deviation predicted by the quadratic equation from measured data. By subtracting the value of the parabola at each mass from the calibrated data, the accuracy of mass data points can be improved by factors of 10 or more. This method produces highly similar results whether or not initial ion velocity is accounted for in the calibration equation; consequently, there is no need to depend on that uncertain parameter when using the quadratic correction. This method can be used to correct the internally calibrated masses of protein digest peaks. The effect of nitrocellulose as a matrix additive is also briefly discussed, and it is shown that using nitrocellulose as an additive to the alpha-cyano-4-hydroxycinnamic acid (alphaCHCA) matrix does not significantly change initial ion velocity but does change the average position of ions relative to the sample electrode at the instant the extraction voltage is applied.

  15. Identification of dermatophytes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    de Respinis, Sophie; Tonolla, Mauro; Pranghofer, Sigrid; Petrini, Liliane; Petrini, Orlando; Bosshard, Philipp P

    2013-07-01

    In this study we evaluated the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of dermatophytes in diagnostic laboratories. First, a spectral database was built with 108 reference strains belonging to 18 species of the anamorphic genera Epidermophyton, Microsporum and Trichophyton. All strains were well characterized by morphological criteria and ITS sequencing (gold standard). The dendrogram resulting from MALDI-TOF mass spectra was almost identical with the phylogenetic tree based on ITS sequencing. Subsequently, MALDI-TOF MS SuperSpectra were created for the identification of Epidermophyton floccosum, Microsporium audouinii, M. canis, M. gypseum (teleomorph: Arthroderma gypseum), M. gypseum (teleomorph: A. incurvatum), M. persicolor, A. benhamiae (Tax. Entity 3 and Am-Eur. race), T. erinacei, T. interdigitale (anthropophilic and zoophilic populations), T. rubrum/T. violaceum, T. tonsurans and T. terrestre. Because T. rubrum and T. violaceum did not present enough mismatches, a SuperSpectrum covering both species was created, and differentiation between them was done by comparison of eight specific peptide masses. In the second part of this study, MALDI-TOF MS with the newly created SuperSpectra was tested using 141 clinical isolates representing nine species. Analyses were done with 3-day-old cultures. Results were compared to morphological identification and ITS sequencing; 135/141 (95.8%) strains were correctly identified by MALDI-TOF MS compared to 128/141 (90.8%) by morphology. Therefore, MALDI-TOF MS has proven to be a useful and rapid identification method for dermatophytes. PMID:23228046

  16. Localization of ferruginol, a diterpene phenol, in Cryptomeria japonica heartwood by time-of-flight secondary ion mass spectrometry.

    PubMed

    Imai, Takanori; Tanabe, Kinuko; Kato, Toshiyuki; Fukushima, Kazuhiko

    2005-06-01

    Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was applied to the investigation of heartwood extractives in Sugi (Cryptomeria japonica). Sugi heartwood tissue generated secondary ions that were not produced from sapwood tissue by TOF-SIMS. Among the peculiar ions generated from heartwood, two positive ions of m/z 285 and 301 were remarkable due to their appearance in a larger mass range and with a high intensity. These two ions were not generated from heartwood tissue preextracted with n-hexane, and the n-hexane extract of Sugi heartwood produced both ions. Gas chromatography-mass spectrometry of the n-hexane extract demonstrated that ferruginol, a diterpene phenol, the molecular weight of which is 286, constituted one of the predominant constituents of the extract. Authentic ferruginol also generated both ions by TOF-SIMS. The molecular formula of the m/z 285 ion generated from Sugi heartwood tissue was estimated to be C(20)H(29)O, which corresponds well with that of ferruginol, i.e. C(20)H(30)O, by peak identification. All these results strongly suggest that the m/z 285 ion generated from Sugi heartwood tissue originated significantly from ferruginol in Sugi heartwood. By TOF-SIMS imaging, the m/z 285 ion was detected uniformly in the tracheid cell walls, in the cell walls of the axial parenchyma cells and ray parenchyma cells, and also inside these parenchyma cells. These results indicate that ferruginol was distributed almost evenly in Sugi heartwood tissue.

  17. Utilisation of electrospray time-of-flight mass spectrometry for solving complex fragmentation patterns: application to benzoxazinone derivatives.

    PubMed

    Bonnington, L S; Barcelò, D; Knepper, T P

    2003-10-01

    In this paper we describe the application of electrospray time-of-flight mass spectrometry (ESI-TOFMS) to structural elucidation of the fragment ions formed from a range of natural and synthetic allelochemical derivatives. The extensive mass spectrometric characterisation of ten non-glucosylated benzoxazinone derivatives using this method is described here for the first time. The analytes include six naturally occurring 1,4-benzoxazin-3(4H)-one derivatives, including the hydroxamic acids DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one] and DIBOA [2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one], lactams HBOA [2-hydroxy-2H-1,4-benzoxazin-3(4H)-one] and HMBOA [2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one], benzoxazolinones BOA [benzoxazolin-2(3H)-one] and MBOA [6-methoxy-benzoxazolin-2(3H)-one] and four synthetic variations, 2'H-DIBOA [4-hydroxy-2H-1,4-benzoxazin-3(4H)-one], 2'OMe-DIBOA [2-methoxy-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one], 2'H-HBOA [2H-1,4-benzoxazin-3(4H)-one] and 2'OMe-HBOA [2-methoxy-2H-1,4-benzoxazin-3(4H)-one]. Assignments of the mass spectral fragments were aided by elemental composition calculation results, comparison of structural analogues and background literature, and acquired knowledge regarding feasible structures for the compounds. The influence of substituents on the chemical reactivity of the compounds with respect to the observed MS behaviour over varying nozzle potentials is addressed and, through comparison of the structural analogues, generic fragmentation patterns have also been identified.

  18. Characterization of an Ion Mobility-Multiplexed Collision Induced Dissociation- Tandem Time-of-Flight Mass Spectrometry Approach

    SciTech Connect

    Ibrahim, Yehia M.; Prior, David C.; Baker, Erin Shammel; Smith, Richard D.; Belov, Mikhail E.

    2010-06-01

    The confidence in peptide (and protein) identifications with ion mobility spectrometry time-of-flight mass spectrometry (IMS-TOFMS) is expected to drastically improve with the addition of information from an efficient ion dissociation step prior to MS detection. High throughput IMS-TOFMS analysis imposes a strong need for multiplexed ion dissociation approaches where multiple precursor ions yield complex sets of fragment ions that are often intermingled with each other in both the drift time and m/z domains. We have developed and evaluated a novel approach for collision-induced dissociation (CID) with an IMS-TOFMS instrument. It has been shown that precursor ions activated inside an rf-device with an axial dc-electric field produce abundant fragment ions which are radially confined with the rf-field and collisionally cooled at an elevated pressure, resulting in high CID efficiencies comparable or higher than those measured in triple-quadrupole instruments We have also developed an algorithm for deconvoluting these complex multiplexed tandem MS spectra by clustering both the precursor and fragment ions into the matching drift time profiles and by effectively utilizing high mass measurement accuracy of the TOFMS. In a single IMS separation with a tryptic digest of bovine serum albumin (BSA), we have reliably identified 20 unique peptides using multiplexed CID approach downstream of the IMS separation. Peptides were identified based upon the correlation between the precursor and fragment drift time profiles and by matching the profile representative masses to those of in silico BSA tryptic peptides and their fragments. The false discovery rate (FDR) of peptide identifications from multiplexed MS/MS spectra was less than 1%.

  19. Searching for anthropogenic contaminants in human breast adipose tissues using gas chromatography-time-of-flight mass spectrometry.

    PubMed

    Hernández, Félix; Portolés, Tania; Pitarch, Elena; López, Francisco J

    2009-01-01

    The potential of gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) for screening anthropogenic organic contaminants in human breast adipose tissues has been investigated. Initially a target screening was performed for a list of 125 compounds which included persistent halogen pollutants [organochlorine (OC) pesticides, polychlorinated biphenylss (PCBs), polybrominated diphenyl ethers (PBDEs)], polyaromatic hydrocarbons (PAHs), alkylphenols, and a notable number of pesticides from the different fungicide, herbicide and insecticide families. Searching for target pollutants was done by evaluating the presence of up to five representative ions for every analyte, all measured at accurate mass (20-mDa mass window). The experimental ion abundance ratios were then compared to those of reference standards for confirmation. Sample treatment consisted of an extraction with hexane and subsequent normal-phase (NP) High performance liquid chromatography (HPLC) or SPE cleanup. The fat-free LC fractions were then investigated by GC-TOF MS.Full-spectral acquisition and accurate mass data generated by GC-TOF MS also allowed the investigation of nontarget compounds using appropriate processing software to manage MS data. Identification was initially based on library fit using commercial nominal mass libraries. This was followed by comparing the experimental accurate masses of the most relevant ions with the theoretical exact masses with calculations made using the elemental composition calculator included in the software.The application of both target and nontarget approaches to around 40 real samples allowed the detection and confirmation of several target pollutants including p,p'-DDE, hexachlorobenzene (HCB), and some polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Several nontarget compounds that could be considered anthropogenic pollutants were also detected. These included 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) and its metabolite 3,5-di

  20. Identification of Tsetse (Glossina spp.) Using Matrix-Assisted Laser Desorption/Ionisation Time of Flight Mass Spectrometry

    PubMed Central

    Hoppenheit, Antje; Murugaiyan, Jayaseelan; Bauer, Burkhard; Steuber, Stephan; Clausen, Peter-Henning; Roesler, Uwe

    2013-01-01

    Glossina (G.) spp. (Diptera: Glossinidae), known as tsetse flies, are vectors of African trypanosomes that cause sleeping sickness in humans and nagana in domestic livestock. Knowledge on tsetse distribution and accurate species identification help identify potential vector intervention sites. Morphological species identification of tsetse is challenging and sometimes not accurate. The matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI TOF MS) technique, already standardised for microbial identification, could become a standard method for tsetse fly diagnostics. Therefore, a unique spectra reference database was created for five lab-reared species of riverine-, savannah- and forest- type tsetse flies and incorporated with the commercial Biotyper 3.0 database. The standard formic acid/acetonitrile extraction of male and female whole insects and their body parts (head, thorax, abdomen, wings and legs) was used to obtain the flies' proteins. The computed composite correlation index and cluster analysis revealed the suitability of any tsetse body part for a rapid taxonomical identification. Phyloproteomic analysis revealed that the peak patterns of G. brevipalpis differed greatly from the other tsetse. This outcome was comparable to previous theories that they might be considered as a sister group to other tsetse spp. Freshly extracted samples were found to be matched at the species level. However, sex differentiation proved to be less reliable. Similarly processed samples of the common house fly Musca domestica (Diptera: Muscidae; strain: Lei) did not yield any match with the tsetse reference database. The inclusion of additional strains of morphologically defined wild caught flies of known origin and the availability of large-scale mass spectrometry data could facilitate rapid tsetse species identification in the future. PMID:23875040

  1. Determination of Dicyandiamide in Powdered Milk Using Direct Analysis in Real Time Quadrupole Time-of-Flight Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Zhang, Liya; Yong, Wei; Liu, Jiahui; Wang, Sai; Chen, Qilong; Guo, Tianyang; Zhang, Jichuan; Tan, Tianwei; Su, Haijia; Dong, Yiyang

    2015-08-01

    The direct analysis in real time (DART) ionization source coupled with quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS) system has the capability to desorb analytes directly from samples without sample cleanup or chromatographic separation. In this work, a method based on DART/Q-TOF MS/MS has been developed for rapid identification of dicyandiamide (DCD) present in powdered milk. Simple sample extraction procedure employing acetonitrile-water (80:20, v/v) mixture was followed by direct, high-throughput determination of sample extracts spread on a steel mesh of the transmission module by mass spectrometry under ambient conditions. The method has been evaluated for both qualitative and quantitative analysis of DCD in powdered milk. Variables including experimental apparatus, DART gas heater temperature, sample presentation speed, and vacuum pressure were investigated. The quantitative method was validated with respect to linearity, sensitivity, repeatability, precision, and accuracy by using external standards. After optimization of these parameters, a limit of detection (LOD) of 100 μg kg-1 was obtained for DCD with a linear working range from 100 to 10000 μg kg-1 and a satisfactory correlation coefficient (R2) of 0.9997. Good recovery (80.08%-106.47%) and repeatability (RSD = 3.0%-5.4%) were achieved for DCD. The DART/Q-TOF MS/MS-based method provides a rapid, efficient, and powerful scheme to analyze DCD in powdered milk with limited sample preparation, thus reducing time and complexity of quality control.

  2. Detection of illicit drugs on surfaces using direct analysis in real time (DART) time-of-flight mass spectrometry.

    PubMed

    Grange, Andrew H; Sovocool, G Wayne

    2011-05-15

    Methamphetamine (meth) from meth syntheses or habitual meth smoking deposited on household surfaces poses human health hazards. The U.S. State Departments of Health require decontamination of sites where meth was synthesized (meth labs) before they are sold. National Institute for Occupational Safety and Health (NIOSH) methods for meth analysis require wipe sampling, extraction, clean-up, solvent exchange, derivatization, and/or mass spectral analysis using selected ion monitoring. Rapid and inexpensive analyses could screen for drug-contamination within structures with greater spatial resolution, provide real-time analyses during decontamination, and provide thorough documentation of successful clean ups. Herein an autosampler/open-air ion source time-of-flight mass spectrometric technique is described that required only direct sampling using cotton-swab wipes. Each wipe sample collection required 2 min and data acquisition required only 13 s per sample. Optimum collision-induced dissociation voltages, desorption gas temperatures, and wipe sample solvents were determined for 11 drugs. Peaks were observed in analyte-ion traces for 0.025 µg/100 cm(2) of meth and seven other drugs. This level is half the detection limit of NIOSH methods and one-fourth of the lowest U.S. state decontamination limit for meth. Dynamic ranges of 100 in concentration were demonstrated for eight drugs, which is sufficient for a screening technique. The volatilities of 11 drugs deposited on glass were determined. The pick up of the drugs by solvent-soaked cotton-swab wipes from glass relative to acrylic latex paint was also compared.

  3. Identification of beer-spoilage bacteria using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Wieme, Anneleen D; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita; Vandamme, Peter

    2014-08-18

    Applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of beer-spoilage bacteria was examined. To achieve this, an extensive identification database was constructed comprising more than 4200 mass spectra, including biological and technical replicates derived from 273 acetic acid bacteria (AAB) and lactic acid bacteria (LAB), covering a total of 52 species, grown on at least three growth media. Sequence analysis of protein coding genes was used to verify aberrant MALDI-TOF MS identification results and confirmed the earlier misidentification of 34 AAB and LAB strains. In total, 348 isolates were collected from culture media inoculated with 14 spoiled beer and brewery samples. Peak-based numerical analysis of MALDI-TOF MS spectra allowed a straightforward species identification of 327 (94.0%) isolates. The remaining isolates clustered separately and were assigned through sequence analysis of protein coding genes either to species not known as beer-spoilage bacteria, and thus not present in the database, or to novel AAB species. An alternative, classifier-based approach for the identification of spoilage bacteria was evaluated by combining the identification results obtained through peak-based cluster analysis and sequence analysis of protein coding genes as a standard. In total, 263 out of 348 isolates (75.6%) were correctly identified at species level and 24 isolates (6.9%) were misidentified. In addition, the identification results of 50 isolates (14.4%) were considered unreliable, and 11 isolates (3.2%) could not be identified. The present study demonstrated that MALDI-TOF MS is well-suited for the rapid, high-throughput and accurate identification of bacteria isolated from spoiled beer and brewery samples, which makes the technique appropriate for routine microbial quality control in the brewing industry. PMID:24929682

  4. Identification of beer-spoilage bacteria using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Wieme, Anneleen D; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita; Vandamme, Peter

    2014-08-18

    Applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of beer-spoilage bacteria was examined. To achieve this, an extensive identification database was constructed comprising more than 4200 mass spectra, including biological and technical replicates derived from 273 acetic acid bacteria (AAB) and lactic acid bacteria (LAB), covering a total of 52 species, grown on at least three growth media. Sequence analysis of protein coding genes was used to verify aberrant MALDI-TOF MS identification results and confirmed the earlier misidentification of 34 AAB and LAB strains. In total, 348 isolates were collected from culture media inoculated with 14 spoiled beer and brewery samples. Peak-based numerical analysis of MALDI-TOF MS spectra allowed a straightforward species identification of 327 (94.0%) isolates. The remaining isolates clustered separately and were assigned through sequence analysis of protein coding genes either to species not known as beer-spoilage bacteria, and thus not present in the database, or to novel AAB species. An alternative, classifier-based approach for the identification of spoilage bacteria was evaluated by combining the identification results obtained through peak-based cluster analysis and sequence analysis of protein coding genes as a standard. In total, 263 out of 348 isolates (75.6%) were correctly identified at species level and 24 isolates (6.9%) were misidentified. In addition, the identification results of 50 isolates (14.4%) were considered unreliable, and 11 isolates (3.2%) could not be identified. The present study demonstrated that MALDI-TOF MS is well-suited for the rapid, high-throughput and accurate identification of bacteria isolated from spoiled beer and brewery samples, which makes the technique appropriate for routine microbial quality control in the brewing industry.

  5. Isomer-specific determination of 4-nonylphenols using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

    USGS Publications Warehouse

    Eganhouse, R.P.; Pontolillo, J.; Gaines, R.B.; Frysinger, G.S.; Gabriel, F.L.P.; Kohler, H.-P.E.; Giger, W.; Barber, L.B.

    2009-01-01

    Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C3-10-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/ ToFMS) was used to characterize tNP samples obtained from seven commercial suppliers. Under optimal chromatographic conditions, 153-204 alkylphenol peaks, 59-66 of which were identified as 4-NPs, were detected. The 4-NPs comprised ???86-94% of tNP, with 2-NPs and decylphenols making up???2-9%and???2-5%, respectively. The tNP products were analyzed for eight synthetic 4-NP isomers, and results were compared with published data based on GC/ MS analysis. Significant differences were found among the products and between two samples from a single supplier. The enhanced resolution of GC x GC coupled with fast mass spectral data acquisition by ToFMS facilitated identification of all major 4-NP isomers and a number of previously unrecognized components. Analysis of tNP altered by the bacterium, Sphingobium xenophagum Bayram, revealed several persistent 4-NPs whose structures and estrogenicities are presently unknown. The potential of this technology for isomer-specific determination of 4-NP isomers in environmental matrices is demonstrated using samples of wastewatercontaminated groundwater and municipal wastewater. ?? 2009 American Chemical Society.

  6. Time of flight secondary ion mass spectrometry of bone-Impact of sample preparation and measurement conditions.

    PubMed

    Henss, Anja; Hild, Anne; Rohnke, Marcus; Wenisch, Sabine; Janek, Juergen

    2015-06-07

    Time of flight secondary ion mass spectrometry (ToF-SIMS) enables the simultaneous detection of organic and inorganic ions and fragments with high mass and spatial resolution. Due to recent technical developments, ToF-SIMS has been increasingly applied in the life sciences where sample preparation plays an eminent role for the quality of the analytical results. This paper focusses on sample preparation of bone tissue and its impact on ToF-SIMS analysis. The analysis of bone is important for the understanding of bone diseases and the development of replacement materials and new drugs for the cure of diseased bone. The main purpose of this paper is to find out which preparation process is best suited for ToF-SIMS analysis of bone tissue in order to obtain reliable and reproducible analytical results. The influence of the embedding process on the different components of bone is evaluated using principal component analysis. It is shown that epoxy resin as well as methacrylate based plastics (Epon and Technovit) as embedding materials do not infiltrate the mineralized tissue and that cut sections are better suited for the ToF-SIMS analysis than ground sections. In case of ground samples, a resin layer is smeared over the sample surface due to the polishing step and overlap of peaks is found. Beside some signals of fatty acids in the negative ion mode, the analysis of native, not embedded samples does not provide any advantage. The influence of bismuth bombardment and O2 flooding on the signal intensity of organic and inorganic fragments due to the variation of the ionization probability is additionally discussed. As C60 sputtering has to be applied to remove the smeared resin layer, its effect especially on the organic fragments of the bone is analyzed and described herein.

  7. Quantitative analysis of pesticide residues in vegetables and fruits by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Saito-Shida, Shizuka; Nemoto, Satoru; Teshima, Reiko; Akiyama, Hiroshi

    2016-01-01

    The applicability of liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) for the quantitative analysis of pesticide residues in vegetables and fruits was demonstrated. The LC-QTOF-MS parameters, such as cone voltage, capillary voltage, collision energy and mass extraction window, were carefully optimised for the analysis of pesticide residues. The LC-QTOF-MS method was validated for 149 pesticides in four vegetables and fruits, i.e. apple, potato, cabbage and spinach, at a spiking level of 0.01 mg kg(-1). The samples were prepared according to the Japanese official multi-residue method with a modification to the column clean-up procedure. Of the 149 pesticides, recoveries in the range of 70-120% were achieved for 147 pesticides in apple, 145 in potato, 141 in cabbage and 131 in spinach, with intra-day precisions (RSDs) of < 25% and inter-day precisions (RSDs) of < 30%, which are within the acceptable range given in the Japanese method validation guideline. Matrix effects were negligible for the majority of the target pesticides. Except for spiroxamine in spinach, no interfering peaks were observed in the blank samples. The target pesticides, except those with low sensitivity, achieved calibration curves with satisfactory linearity, with correlation coefficients (r) greater than 0.995 in the concentration range of 0.002-0.1 μg ml(-1). Furthermore, the majority of the target pesticides provided more than one fragment ion or isotope ion that could be used for confirmation. The overall results suggest that LC-QTOF-MS is a powerful tool for the quantification of pesticide residues in vegetables and fruits at the level of 0.01 mg kg(-1).

  8. Uptake of Ra during the recrystallization of barite: a microscopic and time of flight-secondary ion mass spectrometry study.

    PubMed

    Klinkenberg, Martina; Brandt, Felix; Breuer, Uwe; Bosbach, Dirk

    2014-06-17

    A combined macroscopic and microanalytical approach was applied on two distinct barite samples from Ra uptake batch experiments using time of flight-secondary ion mass spectrometry (ToF-SIMS) and detailed scanning electron microscopy (SEM) investigations. The experiments were set up at near to equilibrium conditions to distinguish between two possible scenarios for the uptake of Ra by already existent barite: (1) formation of a Ba1-xRaxSO4 solid solution surface layer on the barite or (2) a complete recrystallization, leading to homogeneous Ba1-xRaxSO4 crystals. It could be clearly shown that Ra uptake in all barite particles analyzed within this study is not limited to the surface but extends to the entire solid. For most grains a homogeneous distribution of Ra could be determined, indicating a complete recrystallization of barite into a Ba1-xRaxSO4 solid solution. The maxima of the Ra/Ba intensity ratio distribution histograms calculated from ToF-SIMS are identical with the expected Ra/Ba ratios calculated from mass balance assuming a complete recrystallization. In addition, the role of Ra during the recrystallization of barite was examined via detailed SEM investigations. Depending on the type of barite used, an additional coarsening effect or a strong formation of oriented aggregates was observed compared to blank samples without Ra. In conclusion, the addition of Ra to a barite at close to equilibrium conditions has a major impact on the system leading to a fast re-equilibration of the solid to a Ba1-xRaxSO4 solid solution and visible effects on the particle size distribution, even at room temperature.

  9. Determination of exogenous epigallocatechin gallate peracetate in mouse plasma using liquid chromatography with quadrupole time-of-flight mass spectrometry.

    PubMed

    Chu, Kai On; Man, Gene Chi Wai; Chan, Kwok Ping; Chu, Ching Yan; Chan, Tak Hang; Pang, Chi Pui; Wang, Chi Chiu

    2014-12-01

    A robust method for the quantitation of epigallocatechin gallate peracetate in plasma for pharmacokinetic studies is lacking. We have developed a validated method to quantify this compound using liquid chromatography with quadrupole time-of-flight mass spectrometry with isopropanol and tert-butyl methyl ether (3:10) extraction and thin-layer chromatography purification. The epigallocatechin gallate peracetate-1-(13) C8 isotope was used as an internal standard. The linear range (r(2) > 0.9950) was from 0.05 to 100.00 μg/mL. The lower limit of quantification of the method was 0.05 μg/mL. Reproducibility, coefficient of variation, was between 0.7 and 12.6% (n = 6), accuracy between 83.7 and 104.6% (n = 5), and recovery ranged from 82.4 to 109.0% (n = 4). Ion suppression was approximately 40%. No mass spectral peaks were found to interfere between the standard and internal standard or the blank plasma extracts. Epigallocatechin gallate peracetate in plasma was stably stored at -80°C over three months even after three freeze-thaw cycles. Extracts were stable in the sampler at 4°C for over 48 h. Plasma levels were maintained at 1.36 μg/mL for 360 min after intraorbital intravenous injection at 50 mg/kg in mice. This method can be used to reliably measure epigallocatechin gallate peracetate in plasma for pharmacokinetic studies. PMID:25250898

  10. Uptake of Ra during the recrystallization of barite: a microscopic and time of flight-secondary ion mass spectrometry study.

    PubMed

    Klinkenberg, Martina; Brandt, Felix; Breuer, Uwe; Bosbach, Dirk

    2014-06-17

    A combined macroscopic and microanalytical approach was applied on two distinct barite samples from Ra uptake batch experiments using time of flight-secondary ion mass spectrometry (ToF-SIMS) and detailed scanning electron microscopy (SEM) investigations. The experiments were set up at near to equilibrium conditions to distinguish between two possible scenarios for the uptake of Ra by already existent barite: (1) formation of a Ba1-xRaxSO4 solid solution surface layer on the barite or (2) a complete recrystallization, leading to homogeneous Ba1-xRaxSO4 crystals. It could be clearly shown that Ra uptake in all barite particles analyzed within this study is not limited to the surface but extends to the entire solid. For most grains a homogeneous distribution of Ra could be determined, indicating a complete recrystallization of barite into a Ba1-xRaxSO4 solid solution. The maxima of the Ra/Ba intensity ratio distribution histograms calculated from ToF-SIMS are identical with the expected Ra/Ba ratios calculated from mass balance assuming a complete recrystallization. In addition, the role of Ra during the recrystallization of barite was examined via detailed SEM investigations. Depending on the type of barite used, an additional coarsening effect or a strong formation of oriented aggregates was observed compared to blank samples without Ra. In conclusion, the addition of Ra to a barite at close to equilibrium conditions has a major impact on the system leading to a fast re-equilibration of the solid to a Ba1-xRaxSO4 solid solution and visible effects on the particle size distribution, even at room temperature. PMID:24845972

  11. Isomer-specific determination of 4-nonylphenols using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

    PubMed

    Eganhouse, Robert P; Pontolillo, James; Gaines, Richard B; Frysinger, Glenn S; Gabriel, Frédéric L P; Kohler, Hans-Peter E; Giger, Walter; Barber, Larry B

    2009-12-15

    Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C(3-10)-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/ToFMS) was used to characterize tNP samples obtained from seven commercial suppliers. Under optimal chromatographic conditions, 153-204 alkylphenol peaks, 59-66 of which were identified as 4-NPs, were detected. The 4-NPs comprised approximately 86-94% of tNP, with 2-NPs and decylphenols making up approximately 2-9% and approximately 2-5%, respectively. The tNP products were analyzed for eight synthetic 4-NP isomers, and results were compared with published data based on GC/MS analysis. Significant differences were found among the products and between two samples from a single supplier. The enhanced resolution of GC x GC coupled with fast mass spectral data acquisition by ToFMS facilitated identification of all major 4-NP isomers and a number of previously unrecognized components. Analysis of tNP altered by the bacterium, Sphingobium xenophagum Bayram, revealed several persistent 4-NPs whose structures and estrogenicities are presently unknown. The potential of this technology for isomer-specific determination of 4-NP isomers in environmental matrices is demonstrated using samples of wastewater-contaminated groundwater and municipal wastewater. PMID:19924899

  12. High Mass Measurement Accuracy Determination for Proteomics using Multivariate Regression Fitting: Application to Electrospray Ionization Time-Of-Flight Mass Spectrometry

    SciTech Connect

    Strittmatter, Eric F.; Rodriguez, Nestor; Smith, Richard D.

    2003-02-01

    Important factors that limit the mass measurement accuracy from a mass spectrometer are related to (1) the type of mass analyzer used and (2) the data processing/calibration methods used to obtain mass values from the raw data. Here, two data processing methods are presented that correct for systematic deviations when measuring the mass of ions using a time-of-flight (TOF) mass spectrometer. The first fitting method is one where m/z values are obtained from fitting peak distributions using double Gaussian functions. A second calibration method takes into account the slight non-linear response of the time-of-flight analyzer in addition to the drift in the calibration over time. Using multivariate regression, both of these two effects can be corrected for using a single calibration formula. Achievable performance was evaluated with a trypsin digestion of serum albumin and proteins from the organism D. radiodurans that were analyzed using gradient reverse-phase liquid chromatography combined with electrospray ionization orthogonal TOF mass spectrometer. The root mean square deviation between the theoretical and experimental m/z for serum albumin was found to be 8 ppm using the double Gaussian-multivariate method compared to 29 ppm determined using linear calibration and normal peak centroiding. An advantage of the methods presented here is that no calibrant compounds need to be added to the mobile phase, thereby avoiding interference effects and signal suppression of analytes.

  13. Matrix-assisted laser desorption ionization-time of flight mass spectrometry can accurately differentiate Aeromonas dhakensis from A. hydrophila, A. caviae, and A. veronii.

    PubMed

    Chen, Po-Lin; Lee, Tai-Fen; Wu, Chi-Jung; Teng, Shih-Hua; Teng, Lee-Jene; Ko, Wen-Chien; Hsueh, Po-Ren

    2014-07-01

    Among 217 Aeromonas isolates identified by sequencing analysis of their rpoB genes, the accuracy rates of identification of A. dhakensis, A. hydrophila, A. veronii, and A. caviae were 96.7%, 90.0%, 96.7%, and 100.0%, respectively, by the cluster analysis of spectra generated by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

  14. Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry for species identification of nonfermenting Gram-negative bacilli.

    PubMed

    Almuzara, Marisa; Barberis, Claudia; Traglia, Germán; Famiglietti, Angela; Ramirez, Maria Soledad; Vay, Carlos

    2015-05-01

    Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) to identify 396 Nonfermenting Gram-Negative Bacilli clinical isolates was evaluated in comparison with conventional phenotypic tests and/or molecular methods. MALDI-TOF MS identified to species level 256 isolates and to genus or complex level 112 isolates. It identified 29 genera including uncommon species.

  15. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  17. Evaluation of Comprehensive 2-D Gas Chromatography-Time-Of-Flight Mass Spectrometry for 209 Chlorinated Biphenyl Congeners in Two Chromatographic Runs

    EPA Science Inventory

    This research evaluates a recently developed comprehensive 2-D GC coupled with a time-of-flight (TOF) mass spectrometer for the potential separation of 209 PCB congeners, using a sequence of 1-D and 2-D chromatographic modes. In two consecutive chromatographic runs, using a 40 m,...

  18. Probing orientation of immobilized humanized anti-lysozyme variable fragment by time-of-flight secondary-ion mass spectrometry.

    PubMed

    Baio, J E; Cheng, Fang; Ratner, Daniel M; Stayton, Patrick S; Castner, David G

    2011-04-01

    As methods to orient proteins are conceived, techniques must also be developed that provide an accurate characterization of immobilized protein orientation. In this study, X-ray photoelectron spectroscopy (XPS), surface plasmon resonance (SPR), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to probe the orientation of a surface immobilized variant of the humanized anti-lysozyme variable fragment (HuLys Fv, 26 kDa). This protein contained both a hexahistidine tag and a cysteine residue, introduced at opposite ends of the HuLys Fv, for immobilization onto nitrilotriacetic acid (NTA) and maleimide oligo(ethylene glycol) (MEG)-terminated substrates, respectively. The thiol group on the cysteine residue selectively binds to the MEG groups, while the his-tag selectively binds to the Ni-loaded NTA groups. XPS was used to monitor protein coverage on both surfaces by following the change in the nitrogen atomic %. SPR results showed a 10-fold difference in lysozyme binding between the two different HuLys Fv orientations. The ToF-SIMS data provided a clear differentiation between the two samples due to the intensity differences of secondary ions originating from asymmetrically located amino acids in HuLys Fv (histidine: 81, 82, and 110 m/z; phenylalanine: 120 and 131 m/z). An intensity ratio of the secondary ion peaks from the histidine and phenylalanine residues at either end of the protein was then calculated directly from the ToF-SIMS data. The 45% change in this ratio, observed between the NTA and MEG substrates with similar HuLys Fv surface coverages, indicates that the HuLys Fv fragment has opposite orientations on two different surfaces.

  19. Identification of Weissella species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    PubMed Central

    Lee, Meng-Rui; Tsai, Chia-Jung; Teng, Shih-Hua; Hsueh, Po-Ren

    2015-01-01

    Although some Weissella species play beneficial roles in food fermentation and in probiotic products, others such as Weissella confusa are emerging Gram-positive pathogens in immunocompromised hosts. Weissella species are difficult to identify by conventional biochemical methods and commercial automated systems and are easily misidentified as Lactobacillus and Leuconostoc species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly being used for bacterial identification. Little, however, is known about the effectiveness of MALDI-TOF MS in identifying clinical isolates of Weissella to the species level. In this study, we evaluated whether the MALDI-TOF MS Bruker Biotyper system could accurately identify a total of 20 W. confusa and 2 W. cibaria blood isolates that had been confirmed by 16s rRNA sequencing analysis. The MALDI-TOF Biotyper system yielded no reliable identification results based on the current reference spectra for the two species (all score values <1.7). New W. confusa spectra were created by randomly selecting 3 W. confusa isolates and external validation was performed by testing the remaining 17 W. confusa isolates using the new spectra. The new main spectra projection (MSP) yielded reliable score values of >2 for all isolates with the exception of one (score value, 1.963). Our results showed that the MSPs in the current database are not sufficient for correctly identifying W. confusa or W. cibaria. Further studies including more Weissella isolates are warranted to further validate the performance of MALDI-TOF in identifying Weissella species. PMID:26594208

  20. Determination of urinary metabolites of XLR-11 by liquid chromatography-quadrupole time-of-flight mass spectrometry.

    PubMed

    Jang, Moonhee; Kim, In Sook; Park, Yu Na; Kim, Jihyun; Han, Inhoi; Baeck, Seungkyung; Yang, Wonkyung; Yoo, Hye Hyun

    2016-01-01

    Recently, use of novel synthetic cannabinoids has increased greatly despite worldwide efforts to regulate these drugs. XLR-11 ((1-[5'-fluoropentyl]indol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone), a fluorinated synthetic cannabinoid with a tetramethylcyclopropyl moiety, has been frequently abused since 2012. XLR-11 produces a number of metabolites in common with its non-fluorinated parent analogue, UR-144 ((1-pentylindol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone). Therefore, it is essential to develop effective urinary markers to distinguish between these drugs. In this study, we investigated the metabolic profile of authentic human urine specimens from suspected users of XLR-11 using liquid chromatography-quadrupole time-of-flight mass spectrometry. Furthermore, we quantified four potential XLR-11 metabolites by using commercially available reference standards. In vitro metabolism of XLR-11 and UR-144 using human liver microsomes was also investigated to compare patterns of production of hydroxypentyl metabolites. Urine samples were prepared with and without enzymatic hydrolysis, and subjected to solid-phase extraction. We identified 19 metabolites generated by oxidative defluorination, hydroxylation, carboxylation, dehydrogenation, glucuronidation, and combinations of these reactions. Among the identified metabolites, 12 were generated from a cyclopropyl ring-opened XLR-11 degradation product formed during smoking. The XLR-11 metabolite with a hydroxylated 2,4-dimethylpent-1-ene moiety was detected in most specimens after hydrolysis and could be utilized as a specific marker for XLR-11 intake. Quantitative results showed that the concentration ratio of 5- and 4-hydroxypentyl metabolites should also be considered as a useful marker for differentiating between the abuse of XLR-11 and UR-144. PMID:26514671

  1. Microorganisms direct identification from blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Ferreira, L; Sánchez-Juanes, F; Porras-Guerra, I; García-García, M I; García-Sánchez, J E; González-Buitrago, J M; Muñoz-Bellido, J L

    2011-04-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows a fast and reliable bacterial identification from culture plates. Direct analysis of clinical samples may increase its usefulness in samples in which a fast identification of microorganisms can guide empirical treatment, such as blood cultures (BC). Three hundred and thirty BC, reported as positive by the automated BC incubation device, were processed by conventional methods for BC processing, and by a fast method based on direct MALDI-TOF MS. Three hundred and eighteen of them yield growth on culture plates, and 12 were false positive. The MALDI-TOF MS-based method reported that no peaks were found, or the absence of a reliable identification profile, in all these false positive BC. No mixed cultures were found. Among these 318 BC, we isolated 61 Gram-negatives (GN), 239 Gram-positives (GP) and 18 fungi. Microorganism identifications in GN were coincident with conventional identification, at the species level, in 83.3% of BC and, at the genus level, in 96.6%. In GP, identifications were coincident with conventional identification in 31.8% of BC at the species level, and in 64.8% at the genus level. Fungaemia was not reliably detected by MALDI-TOF. In 18 BC positive for Candida species (eight C. albicans, nine C. parapsilosis and one C. tropicalis), no microorganisms were identified at the species level, and only one (5.6%) was detected at the genus level. The results of the present study show that this fast, MALDI-TOF MS-based method allows bacterial identification directly from presumptively positive BC in a short time (<30 min), with a high accuracy, especially when GN bacteria are involved.

  2. Effect of heating strategies on whey protein denaturation--Revisited by liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Akkerman, M; Rauh, V M; Christensen, M; Johansen, L B; Hammershøj, M; Larsen, L B

    2016-01-01

    Previous standards in the area of effect of heat treatment processes on milk protein denaturation were based primarily on laboratory-scale analysis and determination of denaturation degrees by, for example, electrophoresis. In this study, whey protein denaturation was revisited by pilot-scale heating strategies and liquid chromatography quadrupole time-of-flight mass spectrometer (LC/MC Q-TOF) analysis. Skim milk was heat treated by the use of 3 heating strategies, namely plate heat exchanger (PHE), tubular heat exchanger (THE), and direct steam injection (DSI), under various heating temperatures (T) and holding times. The effect of heating strategy on the degree of denaturation of β-lactoglobulin and α-lactalbumin was determined using LC/MC Q-TOF of pH 4.5-soluble whey proteins. Furthermore, effect of heating strategy on the rennet-induced coagulation properties was studied by oscillatory rheometry. In addition, rennet-induced coagulation of heat-treated micellar casein concentrate subjected to PHE was studied. For skim milk, the whey protein denaturation increased significantly as T and holding time increased, regardless of heating method. High denaturation degrees were obtained for T >100°C using PHE and THE, whereas DSI resulted in significantly lower denaturation degrees, compared with PHE and THE. Rennet coagulation properties were impaired by increased T and holding time regardless of heating method, although DSI resulted in less impairment compared with PHE and THE. No significant difference was found between THE and PHE for effect on rennet coagulation time, whereas the curd firming rate was significantly larger for THE compared with PHE. Micellar casein concentrate possessed improved rennet coagulation properties compared with skim milk receiving equal heat treatment.

  3. Probing orientation of immobilized humanized anti-lysozyme variable fragment by time-of-flight secondary-ion mass spectrometry

    PubMed Central

    Baio, J. E.; Cheng, Fang; Ratner, Daniel M.; Stayton, Patrick S.; Castner, David G.

    2011-01-01

    As methods to orient proteins are conceived, techniques must also be developed that provide an accurate characterization of immobilized protein orientation. In this study, x-ray photoelectron spectroscopy (XPS), surface plasmon resonance, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to probe the orientation of a surface immobilized variant of the humanized anti-lysozyme variable fragment (HuLys Fv, 26kDa). This protein contained both a his-tag and a cysteine residue, introduced at opposite ends of the HuLys Fv, for immobilization onto nitrilotriacetic acid (NTA) and maleimide oligo(ethylene glycol) (MEG) terminated substrates, respectively. The thiol group on the cysteine residue selectively binds to the MEG groups, while the his-tag selectively binds to the Ni loaded NTA groups. XPS was used to monitor protein coverage on both surfaces by following the change in the nitrogen atomic %. SPR results showed a 10-fold difference in lysozyme binding between the two different HuLys Fv orientations. The ToF-SIMS data provided a clear differentiation between the two samples due to the intensity differences of secondary ions originating from asymmetrically located amino acids in HuLys Fv (Histidine: 81, 82, and 110 m/z; Phenylalanine: 120 and 131 m/z). An intensity ratio of the secondary-ion peaks from the histidine and phenylalanine residues at either end of the protein was then calculated directly from the ToF-SIMS data. The 45% change in this ratio, observed between the NTA and MEG substrates with similar HuLys Fv surface coverages, indicates the HuLys Fv fragment has opposite orientations on the two different surfaces. PMID:21308984

  4. Identification of Acinetobacter Species Using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

    PubMed Central

    Jeong, Seri; Hong, Jun Sung; Kim, Jung Ok; Kim, Keon-Han; Lee, Woonhyoung; Bae, Il Kwon; Lee, Kyungwon

    2016-01-01

    Background Acinetobacter baumannii has a greater clinical impact and exhibits higher antimicrobial resistance rates than the non-baumannii Acinetobacter species. Therefore, the correct identification of Acinetobacter species is clinically important. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has recently become the method of choice for identifying bacterial species. The purpose of this study was to evaluate the ability of MALDI-TOF MS (Bruker Daltonics GmbH, Germany) in combination with an improved database to identify various Acinetobacter species. Methods A total of 729 Acinetobacter clinical isolates were investigated, including 447 A. baumannii, 146 A. nosocomialis, 78 A. pittii, 18 A. ursingii, 9 A. bereziniae, 9 A. soli, 4 A. johnsonii, 4 A. radioresistens, 3 A. gyllenbergii, 3 A. haemolyticus, 2 A. lwoffii, 2 A. junii, 2 A. venetianus, and 2 A. genomospecies 14TU. After 212 isolates were tested with the default Bruker database, the profiles of 63 additional Acinetobacter strains were added to the default database, and 517 isolates from 32 hospitals were assayed for validation. All strains in this study were confirmed by rpoB sequencing. Results The addition of the 63 Acinetobacter strains' profiles to the default Bruker database increased the overall concordance rate between MALDI-TOF MS and rpoB sequencing from 69.8% (148/212) to 100.0% (517/517). Moreover, after library modification, all previously mismatched 64 Acinetobacter strains were correctly identified. Conclusions MALDI-TOF MS enables the prompt and accurate identification of clinically significant Acinetobacter species when used with the improved database. PMID:27139605

  5. Identification of in vitro metabolites of ethylphenidate by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

    PubMed

    Negreira, Noelia; Erratico, Claudio; van Nuijs, Alexander L N; Covaci, Adrian

    2016-01-01

    Ethylphenidate is a new potent synthetic psychoactive drug, structurally related to methylphenidate. Using human liver microsomes and cytosol, we have investigated for the first time the Phase-I and Phase-II in vitro metabolism of ethylphenidate. The structure of the metabolites was elucidated by hybrid quadrupole time-of-flight mass spectrometry. Overall, seven Phase-I, but no Phase-II metabolites were detected. Ethylphenidate underwent hydroxylation forming two primary mono-hydroxylated metabolites and, subsequently, dehydration and ring opening with an additional hydroxylation, forming secondary metabolites. The involvement of different human cytochrome P450 (CYP) enzymes in the formation of ethylphenidate metabolites was investigated using a panel of human recombinant CYPs (rCYPs). rCYP2C19 was the most active recombinant enzyme involved in the formation of all seven ethylphenidate metabolites detected, although other rCYPs (rCYP1A2, rCYP2B6, rCYPC9, rCYP2D6, and rCYP3A4, but not rCYP2E1) played a role in the metabolism of ethylphenidate. All metabolites identified in the present study can be considered as potential specific biomarkers of ethylphenidate in toxicological studies. Additionally, ritalinic acid and methylphenidate were formed by non-enzymatic hydrolysis and trans-esterification, and, therefore, they cannot be considered as (oxidative) metabolites of ethylphenidate. The presence of methylphenidate and ritalinic acid cannot be exclusively associated to the use of ethylphenidate, since methylphenidate is a drug itself and ritanilic acid can be formed from both ethylphenidate and methylphenidate. PMID:26454340

  6. Development of a Metastable Atom Bombardment (MAB) Source for Penning Ionization Time-of-flight Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Robinson, C. B.; Kimmel, J. R.; David, D.; Jayne, J. T.; Trimborn, A.; Worsnop, D. R.; Jimenez, J. L.

    2009-12-01

    The Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS) utilizes thermal vaporization followed by electron ionization (EI) to convert aerosol components to gas-phase ions. The method enables quantification of chemical classes, but the extensive fragmentation caused by EI limits the specificity of both chemical analysis and source identification by factor analysis. To better identify the molecular components of aerosols, we have constructed a metastable atom bombardment (MAB) ionization source that can be interfaced to standard ToF-AMS hardware. A beam of metastable rare gas atoms is produced by a low-voltage DC discharge and focused toward the vaporization plume, yielding Penning Ionization of the analyte molecules. By changing gases, the excited energies of the metastables can be adjusted between 20.61 eV (He) and 9.92 eV (Kr). Source parameters, including pressures, current, geometry, and materials, were optimized for He, Ar, and Kr. Instrument sensitivity and induced fragmentation was characterized for each using lab-generated oleic acid particles. The demonstrated sensitivities are 0.1% of EI (3% of the SNR of EI in the V-mode, comparable to the Q-AMS SNR), which is sufficient for ambient monitoring. A metastable flux of 2.6e14 sr-1sec-1 has been achieved. The MAB-AMS has been deployed to the FLAME-3 campaign at the USDA Fire Sciences Laboratory in Missoula, MT, and used to sample smoke from open burning of different biomass samples. Preliminary results from FLAME-3 will be presented.

  7. Analysis of psychoactive substances in water by information dependent acquisition on a hybrid quadrupole time-of-flight mass spectrometer.

    PubMed

    Andrés-Costa, María Jesús; Andreu, Vicente; Picó, Yolanda

    2016-08-26

    Emerging drugs of abuse, belonging to many different chemical classes, are attracting users with promises of "legal" highs and easy access via internet. Prevalence of their consumption and abuse through wastewater-based epidemiology can only be realized if a suitable analytical screening procedure exists to detect and quantify them in water. Solid-phase extraction and ultra-high performance liquid chromatography quadrupole time-of-flight-mass spectrometry (UHPLC-QqTOF-MS/MS) was applied for rapid suspect screening as well as for the quantitative determination of 42 illicit drugs and metabolites in water. Using this platform, we were able to identify amphetamines, tryptamines, piperazines, pyrrolidinophenones, arylcyclohexylamines, cocainics, opioids and cannabinoids. Additionally, paracetamol, carbamazepine, ibersartan, valsartan, sulfamethoxazole, terbumeton, diuron, etc. (including degradation products as 3-hydroxy carbamazepine or deethylterbuthylazine) were detected. This method encompasses easy sample preparation and rapid identification of psychoactive drugs against a database that cover more than 2000 compounds that ionized in positive mode, and possibility to identify metabolites and degradation products as well as unknown compounds. The method for river water, influent and effluents samples was fully validated for the target psychoactive substances including assessment of matrix effects (-88-67.8%), recovery (42-115%), precision (<19%) and limits of quantification (1-100ngL(-1)). Method efficiency was thoroughly investigated for a wide range of waste and surface waters. Robust and repeatable functioning of this platform in the screening, identification and quantification of traditional and new psychoactive drugs biomarkers and other water contaminants is demonstrated. PMID:27481402

  8. Analysis of Perilla nankinensis decne essential oil using gas chromatography coupled with time-of-flight mass spectrometry.

    PubMed

    Shashiashvili, N; Jokhadze, M; Tushurashvili, P; Bakuridze, A; Berashvili, D

    2014-04-01

    Perilla is the genus of herbaceous plants of Lamiaceae family. The essential oil of Perilla is believed to be essential part of the herb. It was claimed to have anti-inflammatory, anti-hyperlipidemia, antioxidative and antimicrobial activities. Apart from pharmaceutical and nutrition purposes, It is an edible plant frequently used as a fresh vegetable. It was also applied to produce perfume and cosmetics. Due to the importance of the essential oil from the P. nanakinensis and the lack of detailed studies of them, our work aimed investigation of contents of essential compositions by GC- TOF/MS method. The materials of the study were the aerial parts of P. nankinesis collected at full flowering stage, Guria Region, Georgia. A qualitative analysis of the individual compounds in P. nankinensis essential oil performed by gas chromatography (GC) coupled with time-of-flight mass spectrometer (TOF/MS) for the identification of the resolved peaks. 28 components, which accounted for 77,7% of the oil, were identified. The main components of this essential oil were 1,3,6,10-Dodecatetraene, 3,7,11-trimethyl-, (Z,E)- (α-Farnesene) (34.3%), Caryophyllene oxide (10.2%), 1,6-Octadien-3-ol, 3,7-dimethyl- (linalool) (10.2%). Essential oil also contained humulene (3.9%),caryophyllene (1.9%), methyl salicilate (1.15%), 2-hexanoylfuran (1.0%), gernacrene (1.1%). Based on the results of our experimental data and literature reviews, Perilla essential oil can represent special interest and can be used as an important natural substance for obtaining medicinal and preventive products with the several biological activities.

  9. Quadrupole mass spectrometry and time-of-flight analysis of ions resulting from 532 nm pulsed laser ablation of Ni, Al, and ZnO targets

    SciTech Connect

    Sage, Rebecca S.; Cappel, Ute B.; Ashfold, Michael N. R.; Walker, Nicholas R.

    2008-05-01

    This work describes the design and validation of an instrument to measure the kinetic energies of ions ejected by the pulsed laser ablation (PLA) of a solid target. Mass spectra show that the PLA of Ni, Al, and ZnO targets, in vacuum, using the second harmonic of a Nd:YAG laser (532 nm, pulse duration {approx}10 ns) generates abundant X{sup n+} ions (n{<=}3 for Ni, {<=}2 for Al, {<=}3 and {<=}2 for Zn and O respectively from ZnO). Ions are selected by their mass/charge (m/z) ratio prior to the determination of their times of flight. PLA of Ni has been studied in most detail. The mean velocities of ablated Ni{sup n+} ions are shown to follow the trend v(Ni{sup 3+})>v(Ni{sup 2+})>v(Ni{sup +}). Data from Ni{sup 2+} and Ni{sup 3+} are fitted to shifted Maxwellian functions and agree well with a model which assumes both thermal and Coulombic contributions to ion velocities. The dependence of ion velocities on laser pulse energy (and fluence) is investigated, and the high energy data are shown to be consistent with an effective accelerating voltage of {approx}90 V within the plume. The distribution of velocities associated with Ni{sup 3+} indicates a population at cooler temperature than Ni{sup 2+}.

  10. Sensitivity and fragmentation calibration of the time-of-flight mass spectrometer RTOF on board ESA's Rosetta mission

    NASA Astrophysics Data System (ADS)

    Gasc, Sébastien; Altwegg, Kathrin; Jäckel, Annette; Le Roy, Léna; Rubin, Martin; Fiethe, Björn; Mall, Urs; Rème, Henri

    2014-05-01

    The European Space Agency's Rosetta mission will rendez-vous comet 67P/Churyumov-Gerasimenko (67P) in September 2014. The Rosetta spacecraft with the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) onboard will follow and survey 67P for more than a year until the comet reaches its perihelion and beyond. ROSINA will provide new information on the global molecular, elemental, and isotopic composition of the coma [1]. ROSINA consists of a pressure sensor (COPS) and two mass spectrometers, the Double Focusing Mass Spectrometer (DFMS) and the Reflectron Time Of Flight mass spectrometer (RTOF). RTOF has a wide mass range, from 1 amu/e to >300 amu/e, and contains two ion sources, a reflectron and two detectors. The two ion sources, the orthogonal and the storage source, are capable to measure cometary ions while the latter also allows measuring cometary neutral gas. In neutral gas mode the ionization is performed through electron impact. A built-in Gas Calibration Unit (GCU) contains a known gas mixture composed of He, CO2, and Kr that can be used for in-flight calibration of the instrument. Among other ROSINA specific scientific goals, RTOF's task will be to determine molecular composition of volatiles via measuring and separating heavy hydrocarbons; it has been designed to study the development of the cometary activity as well as the coma chemistry between 3.5 AU and perihelion. From the spectroscopic studies and in-situ observations of other comets, we expect to find molecules such as H2O, CO, CO2, hydrocarbons, alcohols, formaldehyde, and other organic compounds in the coma of 67P/Churyumov-Gerasimenko [2]. To demonstrate and quantify the sensitivity and functionality of RTOF, calibration measurements have been realized with more than 20 species among the most abundant molecules quoted above, as well as other species such as PAHs. We will describe the applied methods used to realize this calibration and will discuss our preliminary results, i

  11. Gas chromatography coupled to tunable pulsed glow discharge time-of-flight mass spectrometry for environmental analysis.

    PubMed

    Solà-Vázquez, Auristela; Lara-Gonzalo, Azucena; Costa-Fernández, José M; Pereiro, Rosario; Sanz-Medel, Alfredo

    2010-05-01

    A tuneable microsecond pulsed direct current glow discharge (GD)-time-of-flight mass spectrometer MS(TOF) developed in our laboratory was coupled to a gas chromatograph (GC) to obtain sequential collection of the mass spectra, at different temporal regimes occurring in the GD pulses, during elution of the analytes. The capabilities of this set-up were explored using a mixture of volatile organic compounds of environmental concern: BrClCH, Cl(3)CH, Cl(4)C, BrCl(2)CH, Br(2)ClCH, Br(3)CH. The experimental parameters of the GC-pulsed GD-MS(TOF) prototype were optimized in order to separate appropriately and analyze the six selected organic compounds, and two GC carrier gases, helium and nitrogen, were evaluated. Mass spectra for all analytes were obtained in the prepeak, plateau and afterpeak temporal regimes of the pulsed GD. Results showed that helium offered the best elemental sensitivity, while nitrogen provided higher signal intensities for fragments and molecular peaks. The analytical performance characteristics were also worked out for each analyte. Absolute detection limits obtained were in the order of ng. In a second step, headspace solid phase microextraction (HS SPME), as sample preparation and preconcentration technique, was evaluated for the quantification of the compounds under study, in order to achieve the required analytical sensitivity for trihalomethanes European Union (EU) environmental legislation. The analytical figures of merit obtained using the proposed methodology showed rather good detection limits (between 2 and 13 microg L(-1) depending on the analyte). In fact, the developed methodology met the EU legislation requirements (the maximum level permitted in tap water for the "total trihalomethanes" is set at 100 microg L(-1)). Real analysis of drinking water and river water were successfully carried out. To our knowledge this is the first application of GC-pulsed GD-MS(TOF) for the analysis of real samples. Its ability to provide elemental

  12. Hybrid quadrupole mass filter/quadrupole ion trap/time-of-flight-mass spectrometer for infrared multiple photon dissociation spectroscopy of mass-selected ions

    SciTech Connect

    Gulyuz, Kerim; Stedwell, Corey N.; Wang Da; Polfer, Nick C.

    2011-05-15

    We present a laboratory-constructed mass spectrometer optimized for recording infrared multiple photon dissociation (IRMPD) spectra of mass-selected ions using a benchtop tunable infrared optical parametric oscillator/amplifier (OPO/A). The instrument is equipped with two ionization sources, an electrospray ionization source, as well as an electron ionization source for troubleshooting. This hybrid mass spectrometer is composed of a quadrupole mass filter for mass selection, a reduced pressure ({approx}10{sup -5} Torr) quadrupole ion trap (QIT) for OPO irradiation, and a reflectron time-of-flight drift tube for detecting the remaining precursor and photofragment ions. A helium gas pulse is introduced into the QIT to temporarily increase the pressure and hence enhance the trapping efficiency of axially injected ions. After a brief pump-down delay, the compact ion cloud is subjected to the focused output from the continuous wave OPO. In a recent study, we implemented this setup in the study of protonated tryptophan, TrpH{sup +}, as well as collision-induced dissociation products of this protonated amino acid [W. K. Mino, Jr., K. Gulyuz, D. Wang, C. N. Stedwell, and N. C. Polfer, J. Phys. Chem. Lett. 2, 299 (2011)]. Here, we give a more detailed account on the figures of merit of such IRMPD experiments. The appreciable photodissociation yields in these measurements demonstrate that IRMPD spectroscopy of covalently bound ions can be routinely carried out using benchtop OPO setups.

  13. Improved analysis of melamine-formaldehyde resins by capillary zone electrophoresis-mass spectrometry using ion-trap and quadrupole-time-of-flight mass spectrometers.

    PubMed

    Vo, Thuy Diep Thanh; Himmelsbach, Markus; Haunschmidt, Manuela; Buchberger, Wolfgang; Schwarzinger, Clemens; Klampfl, Christian W

    2008-12-01

    An improved method based on capillary zone electrophoresis (CZE) coupled to either ion-trap (IT) mass spectrometry (MS) or quadrupole-time-of-flight (Q-TOF) MS for the analysis of melamine-formaldehyde condensates is presented. Employing a formic acid-based electrolyte containing 50% acetonitrile (ACN) and MS detection up to 13 compounds could be determined in lab-made resins, synthesized by mixing formaldehyde and melamine in different ratios ranging from 1:1.5 to 1:4. The use of a Q-TOF-MS for detection allowed the assignment of molecular formulas for all 13 substances with high accuracy.

  14. Analytical strategy based on the combination of gas chromatography coupled to time-of-flight and hybrid quadrupole time-of-flight mass analyzers for non-target analysis in food packaging.

    PubMed

    Cherta, L; Portolés, T; Pitarch, E; Beltran, J; López, F J; Calatayud, C; Company, B; Hernández, F

    2015-12-01

    The potential of an advanced analytical strategy based on the use of gas chromatography (GC) coupled to high resolution mass spectrometry (HRMS) with two different analyzers and ionization sources has been investigated and applied to the non-target analysis of food packaging contaminants. Initially, the approach based on GC-time-of-flight (TOF) MS with electron ionization (EI) source allowed performing a library search and mass accurate measurements of selected ions. Then, a second analysis was performed using hybrid quadrupole (Q) TOF MS with an atmospheric pressure chemical ionization (APCI) source in order to search for the molecular ion or the protonated molecule and study the fragmentation behavior. This analytical strategy was applied to the analysis of four polypropylene/ethylene vinyl alcohol/polypropylene (PP/EVOH/PP) multilayer trays and one PP/Al foil/PP film, each one subjected to migration assays with the food simulants isooctane and Tenax®, in order to investigate its potential on the determination of migrant substances.

  15. Chemical characterization of bio-oils using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

    PubMed

    Tessarolo, Nathalia S; dos Santos, Luciana R M; Silva, Raphael S F; Azevedo, Débora A

    2013-03-01

    The liquid product obtained via the biomass flash pyrolysis is commonly called bio-oil or pyrolysis oil. Bio-oils can be used as sources for chemicals or as fuels, primarily in mixtures or emulsions with fossil fuels. A detailed chemical characterization of bio-oil is necessary to determine its potential uses. Such characterization demands a powerful analytical technique such as comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). Limited chemical information can be obtained from conventional gas chromatography coupled mass spectrometry (GC-MS) because of the large number of compounds and coelutions. Thus, GC×GC-TOFMS was used for the individual identification of bio-oil components from two samples prepared via the flash pyrolysis of empty palm fruit bunch and pine wood chips. To the best of our knowledge, few papers have reported comprehensive two-dimensional gas chromatography (GC×GC) for bio-oil analysis. Many classes of compounds such as phenols, benzenediols, cyclopentenones, furanones, indanones and alkylpyridines were identified. Several coelutions present in the GC-MS were resolved using GC×GC-TOFMS. Many peaks were detected for the samples by GC-MS (~166 and 129), but 631 and 857 were detected by GC×GC-TOFMS, respectively. The GC×GC-TOFMS analyses indicated that the major classes of components (analytes>0.5% relative area) in the two bio-oil samples are ketones, cyclopentenones, furanones, furans, phenols, benzenediols, methoxy- and dimethoxy-phenols and sugars. In addition, esters, aldehydes and pyridines were found for sample obtained from empty palm fruit bunch, while alcohols and cyclopentanediones were found in sample prepared from pine wood chips indicating different composition profiles due to the biomass sources. The elucidation of the composition of empty fruit bunch and pine wood chips bio-oils indicates that these oils are suitable for the production of value-added chemicals. The

  16. Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Cross, E. S.; Onasch, T. B.; Canagaratna, M.; Jayne, J. T.; Kimmel, J.; Yu, X.-Y.; Alexander, M. L.; Worsnop, D. R.; Davidovits, P.

    2008-12-01

    We present the first single particle results obtained using an Aerodyne time-of-flight aerosol mass spectrometer coupled with a light scattering module (LS-ToF-AMS). The instrument was deployed at the T1 ground site approximately 40 km northeast of the Mexico City Metropolitan Area (MCMA) as part of the MILAGRO field study in March of 2006. The instrument was operated as a standard AMS from 12-30 March, acquiring average chemical composition and size distributions for the ambient aerosol, and in single particle mode from 27-30 March. Over a 75-h sampling period, 12 853 single particle mass spectra were optically triggered, saved, and analyzed. The correlated optical and chemical detection allowed detailed examination of single particle collection and quantification within the LS-ToF-AMS. The single particle data enabled the mixing states of the ambient aerosol to be characterized within the context of the size-resolved ensemble chemical information. The particulate mixing states were examined as a function of sampling time and most of the particles were found to be internal mixtures containing many of the organic and inorganic species identified in the ensemble analysis. The single particle mass spectra were deconvolved, using techniques developed for ensemble AMS data analysis, into HOA, OOA, NH4NO3, (NH4)2SO4, and NH4Cl fractions. Average single particle mass and chemistry measurements are shown to be in agreement with ensemble MS and PTOF measurements. While a significant fraction of ambient particles were internal mixtures of varying degrees, single particle measurements of chemical composition allowed the identification of time periods during which the ambient ensemble was externally mixed. In some cases the chemical composition of the particles suggested a likely source. Throughout the full sampling period, the ambient ensemble was an external mixture of combustion-generated HOA particles from local sources (e.g. traffic), with number concentrations peaking

  17. Interlaboratory Comparison of Intact-Cell Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Results for Identification and Differentiation of Brucella spp.

    PubMed Central

    Karger, Axel; Melzer, Falk; Timke, Markus; Bettin, Barbara; Kostrzewa, Markus; Nöckler, Karsten; Hohmann, Angelika; Tomaso, Herbert; Neubauer, Heinrich

    2013-01-01

    Classical microbiological diagnosis of human brucellosis is time-consuming, hazardous, and subject to variable interpretation. Intact-cell matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) was evaluated for the routine identification of Brucella spp. Analysis of mass peak patterns allowed accurate identification to the genus level. However, statistical models based on peak intensities were needed for definite species differentiation. Interlaboratory comparison confirmed the reproducibility of the results. PMID:23850950

  18. Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: a Fundamental Shift in the Routine Practice of Clinical Microbiology

    PubMed Central

    Clark, Andrew E.; Kaleta, Erin J.; Arora, Amit

    2013-01-01

    SUMMARY Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the “nuts and bolts” of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care. PMID:23824373

  19. Matrix-assisted laser desorption ionization-time of flight mass spectrometry: a fundamental shift in the routine practice of clinical microbiology.

    PubMed

    Clark, Andrew E; Kaleta, Erin J; Arora, Amit; Wolk, Donna M

    2013-07-01

    Within the past decade, clinical microbiology laboratories experienced revolutionary changes in the way in which microorganisms are identified, moving away from slow, traditional microbial identification algorithms toward rapid molecular methods and mass spectrometry (MS). Historically, MS was clinically utilized as a high-complexity method adapted for protein-centered analysis of samples in chemistry and hematology laboratories. Today, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS is adapted for use in microbiology laboratories, where it serves as a paradigm-shifting, rapid, and robust method for accurate microbial identification. Multiple instrument platforms, marketed by well-established manufacturers, are beginning to displace automated phenotypic identification instruments and in some cases genetic sequence-based identification practices. This review summarizes the current position of MALDI-TOF MS in clinical research and in diagnostic clinical microbiology laboratories and serves as a primer to examine the "nuts and bolts" of MALDI-TOF MS, highlighting research associated with sample preparation, spectral analysis, and accuracy. Currently available MALDI-TOF MS hardware and software platforms that support the use of MALDI-TOF with direct and precultured specimens and integration of the technology into the laboratory workflow are also discussed. Finally, this review closes with a prospective view of the future of MALDI-TOF MS in the clinical microbiology laboratory to accelerate diagnosis and microbial identification to improve patient care.

  20. Neutron energy and time-of-flight spectra behind the lateral shield of a high energy electron accelerator beam dump. Part II: Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Roesler, S.; Liu, J. C.; Rokni, S. H.; Taniguchi, S.

    2003-05-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight spectra were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  1. Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high-performance liquid chromatography and time-of-flight mass spectrometry

    USGS Publications Warehouse

    Thurman, E.M.; Ferrer, I.; Parry, R.

    2002-01-01

    Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750??0.0049 amu and 270.0786??0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098??0.0061 amu and 314.1153??0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation spectra, which did not occur using negative-ion electrospray.

  2. Angular and internal state distributions of H2 (+) generated by (2 + 1) resonance enhanced multiphoton ionization of H2 using time-of-flight mass spectrometry.

    PubMed

    Perreault, William E; Mukherjee, Nandini; Zare, Richard N

    2016-06-01

    We report direct measurement of the anisotropy parameter β for the angular distribution of the photoelectron and photoion in (2 + 1) resonance enhanced multiphoton ionization process of H2 X (1)Σg (+) (v = 0, J = 0) molecules through the intermediate H2 E,F (1)Σg (+) (v' = 0, J' = 0) level (λ = 201.684 nm) using a time-of-flight mass spectrometer. The time-of-flight spectra were recorded as the direction of polarization of the ionizing laser was varied with respect to the flight axis of the H2 molecular beam and were fitted to an angular distribution in an appropriately rotated coordinate system with the z-axis oriented along the time-of-flight axis. The anisotropy parameter β was found to be 1.72 ± 0.13 by fitting the time-of-flight spectra and agreed with previous measurements. Using secondary ionization with a delayed laser pulse of different wavelength, we also determined the vibrational energy distribution of the ions, showing that 98% ± 4% of the ions are generated in their ground vibrational state, in agreement with the calculated Franck-Condon factors between the H2 E,F (1)Σg (+) (v' = 0) and H2 (+) X (1)Σg (+) (v″) vibrational levels.

  3. Characterization of multiple constituents in Kai-Xin-San prescription and rat plasma after oral administration by liquid chromatography with quadrupole time-of-flight tandem mass spectrometry.

    PubMed

    Zhang, Xiaowen; Li, Qing; Lv, Chunxiao; Xu, Huarong; Liu, Xujia; Sui, Zhenyu; Bi, Kaishun

    2015-06-01

    A sensitive and reliable ultra high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry method was established to separate and identify the chemical constituents of Kai-Xin-San prescription, a classic traditional Chinese medicine formula that plays an important role in the treatment of Alzheimer's disease. The detection was performed on an Agilent 6520 Accurate-Mass quadrupole time-of-flight mass spectrometer equipped with an electrospray ionization source in negative modes. With the optimized conditions, a total of 54 compounds were identified or tentatively characterized. Out of the 54 compounds, six compounds were identified by comparing the retention time and mass spectrometry data with reference standards, the rest were characterized by analyzing mass spectrometry data and retrieving the literature data. Results indicated ginsenosides, polygala saponins, terpenoids, and oligosaccharide esters were the major effective constituents in Kai-Xin-San prescription. There were 26 prototype ingredients that were assigned for identification in rat plasma. It is also concluded that the developed ultra high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry method with high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents of Kai-Xin-San prescription, and the analysis provides a helpful chemical basis for further research on Kai-Xin-San prescription and the clinical diagnostics of Alzheimer's disease.

  4. Characterization of Compounds in Psoralea corylifolia Using High-Performance Liquid Chromatography Diode Array Detection, Time-of-Flight Mass Spectrometry and Quadrupole Ion Trap Mass Spectrometry.

    PubMed

    Tan, Guangguo; Yang, Tiehong; Miao, Huayan; Chen, Hao; Chai, Yifeng; Wu, Hong

    2015-10-01

    High-performance liquid chromatography with diode array detection (HPLC-DAD), time-of-flight mass spectrometry (HPLC-TOFMS) and quadrupole ion trap mass spectrometry (HPLC-QITMS) were used for separation and identification of multi-components in Psoralea corylifolia. Benefiting from combining the accurate mass measurement of HPLC-TOFMS to generate elemental compositions, the complementary multilevel structural information provided by HPLC-QITMS and the characteristic UV spectra obtained from HPLC-DAD, 24 components in P. corylifolia were identified. The five groups of isomers were differentiated based on the fragmentation behaviors in QITMS and UV spectra. It can be concluded that an effective method based on the combination of HPLC-DAD, HPLC-TOFMS and HPLC-QITMS for identification of chemical components in P. corylifolia was established. The results provide essential data for further pharmacological and clinical studies of P. corylifolia and facilitate the rapid quality control of the crude drug.

  5. Systematic screening and characterization of astragalosides in an oral solution of Radix Astragali by liquid chromatography with quadrupole time-of-flight mass spectrometry and Peakview software.

    PubMed

    Li, Chang-Yin; Song, Hui-Ting; Liu, Shi-Jia; Wang, Qiong; Dai, Guo-Liang; Ding, Xuan-Sheng; Ju, Wen-Zheng

    2016-03-01

    Liquid chromatography with quadrupole time-of-flight mass spectrometry coupled with automated data analysis by Peakview software was employed to systematically screen and characterize the astragalosides in Radix Astragali, a Chinese medical preparation. The separation was performed on a poroshell 120 SB-C18 column equipped in a conventional liquid chromatography system. After being separated using a general gradient elution, the analytes were detected by the triple quadrupole time-of-flight mass spectrometer in both positive- and negative-ion modes. The mass defect filtering function built in the Peakview software was utilized to rapidly screen the potential ions of interest, while some functions of Peakview such as Formula Finder, XIC manager, and IDA Explorer were employed to facilitate the assignment or characterization of the screened astragalosides. A total of 42 astragalosides were screened and tentatively characterized or assigned, and 20 of them were firstly detected in Radix Astragali. According to the screened astragalosides, acetylation, glycosidation, hydrogenation, oxidation, and hydration were considered to be the major secondary metabolic pathways involved in the formation of the astragalosides. The combination of liquid chromatography with quadrupole time-of-flight mass spectrometry and automated Peakview analysis is a feasible and efficient tool to screen and identify the constituents in complex matrices of herbal medicines.

  6. High throughput discovery of thermo-responsive materials using water contact angle measurements and time-of-flight secondary ion mass spectrometry.

    PubMed

    Hook, Andrew L; Scurr, David J; Anderson, Daniel G; Langer, Robert; Williams, Paul; Davies, Martyn; Alexander, Morgan

    2013-01-01

    Switchable materials that alter their chemical or physical properties in response to external stimuli allow for temporal control of material-biological interactions, thus, are of interest for many biomaterial applications. Our interest is the discovery of new materials suitable to the specific requirements of certain biological systems. A high throughput methodology has been developed to screen a library of polymers for thermo-responsiveness, which has resulted in the identification of novel switchable materials. To elucidate the mechanism by which the materials switch, time-of-flight secondary ion mass spectrometry has been employed to analyse the top 2 nm of the polymer samples at different temperatures. The surface enrichment of certain molecular fragments has been identified by time-of-flight secondary ion mass spectrometry analysis at different temperatures, suggesting an altered molecular conformation. In one example, a switch between an extended and collapsed conformation is inferred. Copyright © 2012 John Wiley & Sons, Ltd.

  7. Neutron Energy and Time-of-flight Spectra Behind the Lateral Shield of a High Energy Electron Accelerator Beam Dump,Part I: Measurements

    SciTech Connect

    Roesler, Stefan

    2002-09-24

    Neutron energy and time-of-flight spectra were measured behind the lateral shield of the electron beam dump at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were produced by a 28.7 GeV electron beam hitting the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shield. The measurements were performed using a NE213 organic liquid scintillator behind different thicknesses of the concrete shield of 274 cm, 335 cm, and 396 cm, respectively. The neutron energy spectra between 6 and 800 MeV were obtained by unfolding the measured pulse height spectrum with the detector response function. The attenuation length of neutrons in concrete was then derived. The spectra of neutron time-of-flight between beam on dump and neutron detection by NE213 were also measured. The corresponding experimental results were simulated with the FLUKA Monte Carlo code. The experimental results show good agreement with the simulated results.

  8. Neutron energy and time-of-flight spectra behind the lateral shield of a high energy electron accelerator beam dump. Part I: measurements

    NASA Astrophysics Data System (ADS)

    Taniguchi, S.; Nakamura, T.; Nunomiya, T.; Iwase, H.; Yonai, S.; Sasaki, M.; Rokni, S. H.; Liu, J. C.; Kase, K. R.; Roesler, S.

    2003-05-01

    Neutron energy and time-of-flight spectra were measured behind the lateral shield of the electron beam dump at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were produced by a 28.7 GeV electron beam hitting the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shield. The measurements were performed using an NE213 organic liquid scintillator behind different thicknesses of the concrete shield of 274, 335, and 396 cm, respectively. The neutron energy spectra between 6 and 800 MeV were obtained by unfolding the measured pulse height spectrum with the detector response function. The attenuation length of neutrons in concrete was then derived. The spectra of neutron time-of-flight between beam on dump and neutron detection by NE213 were also measured. The corresponding experimental results were simulated with the FLUKA Monte Carlo code. The experimental results show good agreement with the simulated results.

  9. Differentiation of Raoultella ornithinolytica/planticola and Klebsiella oxytoca clinical isolates by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

    PubMed

    de Jong, Eefje; de Jong, Arjan S; Smidts-van den Berg, Nathalie; Rentenaar, Rob J

    2013-04-01

    Ninety-nine clinical isolates previously identified as Klebsiella oxytoca were evaluated using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight isolates were identified as Raoultella spp., being 5 Raoultella spp. and 3 K. oxytoca, by 16S rRNA sequencing. These isolates were correctly identified by applying the 10% differential rule for the MALDI-TOF MS score values. This approach might be useful to discriminate Raoultella species from K. oxytoca.

  10. Analysis of Melamine, Cyanuric Acid, Ammelide, and Ammeline Using Matrix-Asssisted Laser Desorption Ionization/Time-of-Flight Mass Spectrometry (MALDI/TOFMS)

    SciTech Connect

    Campbell, James A.; Wunschel, David S.; Petersen, Catherine E.

    2007-12-01

    Melamine and cyanuric acid, two compounds connected to tainted pet food, have been analyzed using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. (M+H)+ ions were observed for melamine, ammelide, and ammeline under positive ion conditions with sinapinic acid as the matrix. With alpha-cyano-4-hydroxy-cinnamic acid as the matrix, a matrix-melamine complex was observed. (M-H)- was observed for cyanuric acid with sinapinic acid as the matrix.

  11. Identification of Non-diphtheriae Corynebacterium by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Alatoom, Adnan A.; Cazanave, Charles J.; Cunningham, Scott A.; Ihde, Sherry M.

    2012-01-01

    We evaluated the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry for identification of 92 clinical isolates of Corynebacterium species in comparison to identification using rpoB or 16S rRNA gene sequencing. Eighty isolates (87%) yielded a score of ≥1.700, and all of these were correctly identified to the species level with the exception of Corynebacterium aurimucosum being misidentified as the closely related Corynebacterium minutissimum. PMID:22075579

  12. Influence of Culture Media on Detection of Carbapenem Hydrolysis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Ramos, Ana Carolina; Carvalhaes, Cecília Godoy; Cordeiro-Moura, Jhonatha Rodrigo; Rockstroh, Anna Carolina; Machado, Antonia Maria Oliveira; Gales, Ana Cristina

    2016-07-01

    In this study, we evaluated the influence of distinct bacterial growth media on detection of carbapenemase hydrolysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. False-negative results were observed for OXA-25-, OXA-26-, and OXA-72-producing Acinetobacter baumannii isolates grown on MacConkey agar medium. The other culture media showed 100% sensitivity and 100% specificity for detecting carbapenemase.

  13. Identification of Neisseria gonorrhoeae by the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry System Is Improved by a Database Extension.

    PubMed

    Schweitzer, Valentijn A; van Dam, Alje P; Hananta, I Putu Yuda; Schuurman, Rob; Kusters, Johannes G; Rentenaar, Rob J

    2016-04-01

    Identification ofNeisseria gonorrhoeaeby the Bruker matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system may be affected by "B consistency categorization." A supplementary database of 17N. gonorrhoeaemain spectra was constructed. Twelve of 64N. gonorrhoeaeidentifications were categorized with B consistency, which disappeared using the supplementary database. Database extension did not result in misidentification ofNeisseria meningitidis. PMID:26763972

  14. Influence of Culture Media on Detection of Carbapenem Hydrolysis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

    PubMed

    Ramos, Ana Carolina; Carvalhaes, Cecília Godoy; Cordeiro-Moura, Jhonatha Rodrigo; Rockstroh, Anna Carolina; Machado, Antonia Maria Oliveira; Gales, Ana Cristina

    2016-07-01

    In this study, we evaluated the influence of distinct bacterial growth media on detection of carbapenemase hydrolysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. False-negative results were observed for OXA-25-, OXA-26-, and OXA-72-producing Acinetobacter baumannii isolates grown on MacConkey agar medium. The other culture media showed 100% sensitivity and 100% specificity for detecting carbapenemase. PMID:27076665

  15. A Simple and Safe Protocol for Preparing Brucella Samples for Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Analysis

    PubMed Central

    Mesureur, Jennifer; Ranaldi, Sébastien; Monnin, Valérie; Girard, Victoria; Arend, Sandrine; Welker, Martin; O'Callaghan, David

    2015-01-01

    We describe a simple protocol to inactivate the biosafety level 3 (BSL3) pathogens Brucella prior to their analysis by matrix-assisted laser desorption ionization–time of flight mass spectrometry. This method is also effective for several other bacterial pathogens and allows storage, and eventually shipping, of inactivated samples; therefore, it might be routinely applied to unidentified bacteria, for the safety of laboratory workers. PMID:26582837

  16. Identification of Neisseria gonorrhoeae by the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System Is Improved by a Database Extension

    PubMed Central

    Schweitzer, Valentijn A.; van Dam, Alje P.; Hananta, I Putu Yuda; Schuurman, Rob; Kusters, Johannes G.

    2016-01-01

    Identification of Neisseria gonorrhoeae by the Bruker matrix-assisted laser desorption ionization−time of flight mass spectrometry (MALDI-TOF MS) system may be affected by “B consistency categorization.” A supplementary database of 17 N. gonorrhoeae main spectra was constructed. Twelve of 64 N. gonorrhoeae identifications were categorized with B consistency, which disappeared using the supplementary database. Database extension did not result in misidentification of Neisseria meningitidis. PMID:26763972

  17. Renaissance of gas chromatography-time-of-flight mass spectrometry. Meeting the challenge of capillary columns with a beam deflection instrument and time array detection.

    PubMed

    Watson, J T; Schultz, G A; Tecklenburg, R E; Allison, J

    1990-10-01

    This report describes the use of a unique beam deflection time-of-flight mass spectrometer to address some of the demands made on mass spectrometry by new developments in high-resolution capillary column gas chromatography. An integrating transient recorder is used in combination with this beam deflection time-of-flight instrument to apply the concept of time array detection in capturing all of the mass spectral information available from the ion source, thereby greatly enhancing the signal-to-noise ratio quality of the mass spectral data. The applicability of the time array detection approach to gas chromatography-mass spectrometry is demonstrated in the context of an analysis of the standard Grob mixture for assessing performance of capillary column chromatography. During analysis of the Grob mixture by gas chromatography-mass spectrometry, mass spectra were recorded at a rate of 20 scan files per second. The data indicate that this rate of mass spectral scan file generation is adequate to provide a suitable data base for reconstruction of the chromatographic profile. In addition, the effective scan rate is high enough that there is no distortion in the relative peak intensities throughout the individual mass spectra of components regardless of the relatively high dynamic changes in partial pressure of the analyte as reflected by the sharp peaks in the chromatographic profile. The experimental results indicate that the beam deflection time-of-flight mass spectrometer can provide mass spectra at a scan file generation rate much higher than that possible with the conventional quadrupole or magnetic sector mass spectrometer, but at comparable detection limits.

  18. Chemical characterisation of different separation media based on agarose by static time-of-flight secondary ion mass spectrometry.

    PubMed

    Johansson, Bo-Lennart; Andersson, Mikael; Lausmaa, Jukka; Sjövall, Peter

    2004-01-01

    In this paper, the novel application of time-of-flight secondary ion mass spectrometry (TOF-SIMS) for qualitative and semi-quantitative investigation of the surface chemistry of separation media based on beaded agarose is reported. Five different media were studied: DEAE Sepharose Fast Flow, Q Sepharose Fast Flow, SP Sepharose Fast Flow, Phenyl Sepharose Fast Flow at ligand densities between 7 and 33% (w/w) and the base matrix Sepharose 6 Fast Flow. The obtained TOF-SIMS spectra reveal significant chemical information regarding the ligands (DEAE, Q, SP and Phenyl) which are covalently attached to the agarose-based matrix Sepharose 6 Fast Flow. For the anion-exchange media (DEAE and Q Sepharose Fast Flow), the positive TOF-SIMS spectra yielded several strong characteristic fragment peaks from the amine ligands. Structural information was obtained, e.g. from the peak at m/z 173.20, originating from the ion structure [(C2H5)2NCH2CH2NH(C2H5)2l+, which shows that the ligand in DEAE Sepharose Fast Flow is composed of both tertiary and quaternary amines. The positive spectrum of Phenyl Sepharose Fast Flow contained major fragments both from the base matrix and the ligand. The cation-exchanger (SP Sepharose Fast Flow) gave rise to a positive spectrum resembling that of the base matrix (Sepharose 6 Fast Flow) but with a different intensity pattern of the matrix fragments. In addition, peaks with low intensity at m/z 109.94, 125.94 and 139.95 corresponding to Na2SO2+, Na2SO3+ and Na2SO3CH2+, respectively, were observed. The positive TOF-SIMS spectrum of Sepharose 6 Fast Flow contains a large number of fragments in the mass range up to m/z 200 identified as CxHyOz and CxHy structures. The results clearly show that positive TOF-SIMS spectra of different media based on Sepharose 6 Fast Flow are strongly influenced by the ligand coupled to the matrix. The negative TOF-SIMS spectra contained several ligand-specific, characteristic peaks for the cation-exchanger, having sulphonate

  19. Functional wave time-lag focusing matrix-assisted laser desorption/ionization in a linear time-of-flight mass spectrometer: improved mass accuracy.

    PubMed

    Whittal, R M; Russon, L M; Weinberger, S R; Li, L

    1997-06-01

    A strength of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is its ability to analyze mixtures without separation. MALDI mass spectrometers capable of providing a linear mass calibration over a broad mass range should find wide use in these applications. This work addresses issues pertinent to mass measurement accuracy of a time-lag focusing MALDI time-of-flight instrument and presents a new approach to improving mass accuracy by using a functional wave extraction pulse, instead of a square wave, for time-lag focusing. A model is described of an ideal extraction pulse shape that provides constant total kinetic energy for all ions. If total kinetic energy is constant, then there is an exact linear correlation between ion mass and flight time raised to the second power. Using a descending wave extraction pulse, it is demonstrated that mass accuracy of better than 30 ppm using two internal calibrants and better than 70 ppm using external calibrants can be obtained over a 25 ku mass range. The practical aspects of an instrument needed to obtain consistent mass accuracy is discussed. It is found that ion flight time shows a small dependence upon laser flux; flight times increase slightly as the flux increases. But this dependence is much smaller than is observed in continuous-extraction MALDI.

  20. High mass resolution, high angular acceptance time-of-flight mass spectroscopy for planetary missions under the Planetary Instrument Definition and Development Program (PIDDP)

    NASA Technical Reports Server (NTRS)

    Young, David T.

    1991-01-01

    This final report covers three years and several phases of work in which instrumentation for the Planetary Instrument Definition and Development Program (PIDDP) were successfully developed. There were two main thrusts to this research: (1) to develop and test methods for electrostatically scanning detector field-of-views, and (2) to improve the mass resolution of plasma mass spectrometers to M/delta M approximately 25, their field-of-view (FOV) to 360 degrees, and their E-range to cover approximately 1 eV to 50 keV. Prototypes of two different approaches to electrostatic scanning were built and tested. The Isochronous time-of-flight (TOF) and the linear electric field 3D TOF devices were examined.

  1. Qualitative Characterization of the Aqueous Fraction from Hydrothermal Liquefaction of Algae Using 2D Gas Chromatography with Time-of-flight Mass Spectrometry.

    PubMed

    Maddi, Balakrishna; Panisko, Ellen; Albrecht, Karl; Howe, Daniel

    2016-01-01

    Two-dimensional gas chromatography coupled with time-of-flight mass spectrometry is a powerful tool for identifying and quantifying chemical components in complex mixtures. It is often used to analyze gasoline, jet fuel, diesel, bio-diesel and the organic fraction of bio-crude/bio-oil. In most of those analyses, the first dimension of separation is non-polar, followed by a polar separation. The aqueous fractions of bio-crude and other aqueous samples from biofuels production have been examined with similar column combinations. However, sample preparation techniques such as derivatization, solvent extraction, and solid-phase extraction were necessary prior to analysis. In this study, aqueous fractions obtained from the hydrothermal liquefaction of algae were characterized by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry without prior sample preparation techniques using a polar separation in the first dimension followed by a non-polar separation in the second. Two-dimensional plots from this analysis were compared with those obtained from the more traditional column configuration. Results from qualitative characterization of the aqueous fractions of algal bio-crude are discussed in detail. The advantages of using a polar separation followed by a non-polar separation for characterization of organics in aqueous samples by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry are highlighted. PMID:27022829

  2. Detection of ricin in complex samples by immunocapture and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed

    Duriez, Elodie; Fenaille, François; Tabet, Jean-Claude; Lamourette, Patricia; Hilaire, Didier; Becher, François; Ezan, Eric

    2008-09-01

    Ricin, the toxin component of Ricinus communis is considered as a potential chemical weapon. Several complementary techniques are required to confirm its presence in environmental samples. Here, we report a method combining immunocapture and analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the accurate detection of different species of R. communis. Liquid environmental samples were applied to magnetic particles coated with a monoclonal antibody directed against the B-chain of the toxin. After acidic elution, tryptic peptides of the A- and B-chains were obtained by accelerated digestion with trypsin in the presence of acetonitrile. Of the 20 peptides observed by MALDI-TOF MS, three were chosen for detection ( m/ z 1013.6, m/ z 1310.6 and m/ z 1728.9, which correspond to peptides 161-LEQLAGNLR-169, 150-YTFAFGGNYDR-160, and 233-SAPDPSVITLENSWGR-248, respectively). Their selection was based on several parameters such as detection sensitivity, specificity toward ricin forms and absence of isotopic overlap with unrelated peptides. To increase assay reproducibility, stable isotope-labeled peptides were incorporated during the sample preparation phase. The final assay has a limit of detection estimated at approximately 50 ng/mL ( approximately 0.8 nM) of ricin in buffer. No interference was observed when the assay was applied to ricin-spiked milk samples. In addition, several varieties of R. communis or from different geographical origins were also shown to be detectable. The present assay provides a new tool with a total analytical time of approximately 5 h, which is particularly relevant in the context of a bioterrorist incident. PMID:18651759

  3. Top-down proteomic identification of Shiga toxin 2 subtypes from Shiga toxin-producing Escherichia coli by Matrix-Assisted Laser Desorption Ionization-Tandem Time of Flight mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have analyzed 26 Shiga toxin-producing Escherichia coli (STEC) strains for Shiga toxin 2 (Stx2) production using matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomic analysis. STEC strains were induced to ...

  4. Elucidation of high micro-heterogeneity of an acidic-neutral trichotoxin mixture from Trichoderma harzianum by electrospray ionization quadrupole time-of-flight mass spectrometry.

    PubMed

    Suwan, S; Isobe, M; Kanokmedhakul, S; Lourit, N; Kanokmedhakul, K; Soytong, K; Koga, K

    2000-12-01

    The high micro-heterogeneity of an acidic-neutral trichotoxin mixture from T. harzianum, PC01, was elucidated using a modern tandem mass spectrometer equipped with an electrospray ionization source, a hybrid quadrupole-orthogonal accelerator and a reflectron time-of-flight analyzer. The trichotoxins appeared predominantly in six possible doubly charged pseudo molecular ions with three different adducts (H, Na and K) as [M + 2H](2+), [M + H + Na](2+), [M + H + K](2+), [M + 2Na](2+), [M + Na + K](2+) and [M + 2K](2+). The singly charged pseudomolecular ions, [M + H](+), [M + Na](+) and [M + K](+), occurred only in low abundance when the cone voltages were higher than 30 V. Additional singly charged fragments, b(12) and y"6 (complementary N- and C-terminal fragments), were obtained in high abundance using high cone voltages. The peak patterns of both singly and doubly charged molecular adducts revealed that this trichotoxin mixture contained several components having 6-7 molecular masses with a consecutive 14 u difference among members in the same molecular adduct series. Furthermore, well resolved isotopic peaks of every doubly or singly charged ions and their reproducible peak intensity allowed the identification of the mixing of acidic trichotoxins 1 u molecular mass heavier than the neutral counterparts in the sample. Tandem mass spectrometric (MS/MS) analyses of various singly charged b(12) and y"6 ions supported the sequence deduction of the major and minor components and also the position of Glu in the sequences of these acidic molecules. The setting of either low or high resolution of the quadrupole mass filter unit together with a suitable variation of the collision voltage for any MS/MS precursor were the tools for extracting a number of mixed components and obtaining the major and minor sequences of these precursor peaks. The nature of the MS/MS fragmentation and the data assignment of three major doubly charged ions, [M + 2H](2+), [M + K + H](2+) and [M

  5. A technique for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble aromatic polyamides.

    PubMed

    Gies, Anthony P; Nonidez, William K

    2004-04-01

    Wet grinding methods for obtaining matrix-assisted laser desorption/ionization time-of-flight mass spectra of poorly soluble and insoluble low molecular mass oligomers (<4600 Da) of Nomex and Kevlar are described. Optimum conditions for sample preparation are given along with a detailed analysis of the spectra obtained. Two matrix materials were employed in this analysis, 1,8-dihydroxyanthrone (dithranol) and 3-aminoquinoline with potassium trifluoroacetate used as the cationizing agent. The spectra obtained in this study are sensitive to the matrix, molar mixing ratios of matrix/polymer/cationizing agent, and the sample preparation method. PMID:15053662

  6. FiehnLib: mass spectral and retention index libraries for metabolomics based on quadrupole and time-of-flight gas chromatography/mass spectrometry.

    PubMed

    Kind, Tobias; Wohlgemuth, Gert; Lee, Do Yup; Lu, Yun; Palazoglu, Mine; Shahbaz, Sevini; Fiehn, Oliver

    2009-12-15

    At least two independent parameters are necessary for compound identification in metabolomics. We have compiled 2 212 electron impact mass spectra and retention indices for quadrupole and time-of-flight gas chromatography/mass spectrometry (GC/MS) for over 1000 primary metabolites below 550 Da, covering lipids, amino acids, fatty acids, amines, alcohols, sugars, amino-sugars, sugar alcohols, sugar acids, organic phosphates, hydroxyl acids, aromatics, purines, and sterols as methoximated and trimethylsilylated mass spectra under electron impact ionization. Compounds were selected from different metabolic pathway databases. The structural diversity of the libraries was found to be highly overlapping with metabolites represented in the BioMeta/KEGG pathway database using chemical fingerprints and calculations using Instant-JChem. In total, the FiehnLib libraries comprised 68% more compounds and twice as many spectra with higher spectral diversity than the public Golm Metabolite Database. A range of unique compounds are present in the FiehnLib libraries that are not comprised in the 4345 trimethylsilylated spectra of the commercial NIST05 mass spectral database. The libraries can be used in conjunction with GC/MS software but also support compound identification in the public BinBase metabolomic database that currently comprises 5598 unique mass spectra generated from 19,032 samples covering 279 studies of 47 species (plants, animals, and microorganisms).

  7. An iodide-adduct high-resolution time-of-flight chemical-ionization mass spectrometer: application to atmospheric inorganic and organic compounds.

    PubMed

    Lee, Ben H; Lopez-Hilfiker, Felipe D; Mohr, Claudia; Kurtén, Theo; Worsnop, Douglas R; Thornton, Joel A

    2014-06-01

    A high-resolution time-of-flight chemical-ionization mass spectrometer (HR-ToF-CIMS) using Iodide-adducts has been characterized and deployed in several laboratory and field studies to measure a suite of organic and inorganic atmospheric species. The large negative mass defect of Iodide, combined with soft ionization and the high mass-accuracy (<20 ppm) and mass-resolving power (R>5500) of the time-of-flight mass spectrometer, provides an additional degree of separation and allows for the determination of elemental compositions for the vast majority of detected ions. Laboratory characterization reveals Iodide-adduct ionization generally exhibits increasing sensitivity toward more polar or acidic volatile organic compounds. Simultaneous retrieval of a wide range of mass-to-charge ratios (m/Q from 25 to 625 Th) at a high frequency (>1 Hz) provides a comprehensive view of atmospheric oxidative chemistry, particularly when sampling rapidly evolving plumes from fast moving platforms like an aircraft. We present the sampling protocol, detection limits and observations from the first aircraft deployment for an instrument of this type, which took place aboard the NOAA WP-3D aircraft during the Southeast Nexus (SENEX) 2013 field campaign.

  8. Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family

    PubMed Central

    Nguyen, Thao; Aparicio, Mario; Saleh, Mahmoud A.

    2016-01-01

    The triacylglycerol (TAG) structure and the regio-stereospecific distribution of fatty acids (FA) of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens), caraway (Carum carvi), cumin (Cuminum cyminum), coriander (Coriandrum sativum), anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), fennel (Foeniculum vulgare), and Khella (Ammi visnaga), all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v) using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs) from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES) using 1% boron trifluoride (BF3) in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF) mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF) mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0), palmitoleic (C16:1n-9), stearic (C18:0), petroselinic (C18:1n-12), linoleic (C18:2n-6), linolinic (18:3n-3), and arachidic (C20:0) acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS) techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in

  9. Accurate Mass GC/LC-Quadrupole Time of Flight Mass Spectrometry Analysis of Fatty Acids and Triacylglycerols of Spicy Fruits from the Apiaceae Family.

    PubMed

    Nguyen, Thao; Aparicio, Mario; Saleh, Mahmoud A

    2015-01-01

    The triacylglycerol (TAG) structure and the regio-stereospecific distribution of fatty acids (FA) of seed oils from most of the Apiaceae family are not well documented. The TAG structure ultimately determines the final physical properties of the oils and the position of FAs in the TAG molecule affects the digestion; absorption and metabolism; and physical and technological properties of TAGs. Fixed oils from the fruits of dill (Anethum graveolens), caraway (Carum carvi), cumin (Cuminum cyminum), coriander (Coriandrum sativum), anise (Pimpinella anisum), carrot (Daucus carota), celery (Apium graveolens), fennel (Foeniculum vulgare), and Khella (Ammi visnaga), all from the Apiaceae family, were extracted at room temperature in chloroform/methanol (2:1 v/v) using percolators. Crude lipids were fractionated by solid phase extraction to separate neutral triacylglycerols (TAGs) from other lipids components. Neutral TAGs were subjected to transesterification process to convert them to their corresponding fatty acids methyl esters (FAMES) using 1% boron trifluoride (BF₃) in methanol. FAMES were analyzed by gas chromatography-quadrupole time of flight (GC-QTOF) mass spectrometry. Triglycerides were analyzed using high performance liquid chromatography-quadrupole time of flight (LC-QTOF) mass spectrometry. Petroselinic acid was the major fatty acid in all samples ranging from 57% of the total fatty acids in caraway up to 82% in fennel. All samples contained palmitic (16:0), palmitoleic (C16:1n-9), stearic (C18:0), petroselinic (C18:1n-12), linoleic (C18:2n-6), linolinic (18:3n-3), and arachidic (C20:0) acids. TAG were analyzed using LC-QTOF for accurate mass identification and mass spectrometry/mass spectrometry (MS/MS) techniques for regiospesific elucidation of the identified TAGs. Five major TAGs were detected in all samples but with different relative concentrations in all of the tested samples. Several other TAGs were detected as minor components and were present in

  10. Complex mixture analysis based on gas chromatography-mass spectrometry with time array detection using a beam deflection time-of-flight mass spectrometer.

    PubMed

    Schultz, G A; Chamberlin, B A; Sweeley, C C; Watson, J T; Allison, J

    1992-01-31

    A beam deflection time-of-flight mass spectrometer was developed in conjunction with an integrating transient recorder to provide time array detection, permitting high mass spectral scan file acquisition rates for complex mixture analysis by capillary gas chromatography-mass spectrometry (GC-MS). Results are presented for the analysis of a urinary organic acid mixture by GC-MS at a scan file acquisition rate of 10 scan files per second (sf/s), showing the advantages of such data collection in the deconvolution of partially resolved components. The reconstructed total ion current (RTIC) chromatogram available from data acquired at this scan file generation rate is shown to be comparable to the profile obtained from a flame ionization detector in representing the chromatography performed under identical experimental parameters. The RTIC chromatogram available from the database obtained at 10 sf/s is compared with that available from a database obtained at 1 sf/s, the latter representing that scan rate typically used with most GC-MS instruments. The advantages of the higher scan file acquisition rate in representing the chromatographic profile and in allowing mass spectral data to be obtained for components in the complex mixture that are unresolved chromatographically are discussed.

  11. Advanced 360o FOV, wide energy range, non-HV, gated time of flight mass spectrometers for Small Satellites and Cubesats

    NASA Astrophysics Data System (ADS)

    Paschalidis, N.; Jones, S.; Rodriguez, M.; Sittler, E. C., Jr.; Chornay, D. J.; Uribe, P.; Cameron, T.; Nanan, G.

    2015-12-01

    The time of flight technique is widely used for composition analysis of space plasma instruments. The foil - MCP/CEM combination is commonly used for E x TOF mass analysis at the cost of energy threshold, scattering, and direct particle interaction which ultimately affect performance. An alternative method especially effective at low energies is gated time of flight where the start foil is replaced with electric gating. There are several advantages of electric gating, including elimination of heavy HVPS required for pre-reacceleration to overcome foil thresholds, non- destructive interaction with atomic and molecular ions before analysis, and electronic controllability including geometric factor adjustment for flux dynamic range, FOV optimization, electronic filtering of most abundant elements in favor of minor species, and other properties affecting directly the scientific and engineering performance of the instruments. In addition special secondary emission surfaces can be used for triple coincidence when needed. The combination of electric gating and special surfaces works in an extensive energy range from 0 to tens of KeV without the need of start foil/HVPS making thus the use attractive to small satellites and cubesats. Those characteristics will be elaborated in the context of a gated time of flight wide field of view and energy range ion spectrometer combined with a neutral mass spectrometer (WINMS) developed at GSFC. The instrument prototypes have mass resolution adequate to separate N, O, OH, OH2; also static from ram moving H allowing thus separation of outgassing from ambient gases. A first implementation INMS with a mass <600 grams and size <1.5U is the main payload of the EXOCUBE Cubesat mission launched in January 2015 and already produced flight data; a second upgraded implementation is on onboard the GSFC Dellingr 6U CubeSat scheduled for launch in late 2015; and ongoing developments are baselined for other satellite missions.

  12. Building an empirical mass spectra library for screening of organic pollutants by ultra-high-pressure liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry.

    PubMed

    Díaz, Ramón; Ibáñez, María; Sancho, Juan V; Hernández, Félix

    2011-01-30

    Hybrid quadrupole time-of-flight mass spectrometry (QTOF MS) has gained wide acceptance in many fields of chemistry, for example, proteomics, metabolomics and small molecule analysis. This has been due to the numerous technological advances made to this mass analyser in recent years. In the environmental field, the instrument has proven to be one of the most powerful approaches for the screening of organic pollutants in different matrices due to its high sensitivity in full acquisition mode and mass accuracy measurements. In the work presented here, the optimum experimental conditions for the creation of an empirical TOF MS spectra library have been evaluated. For this model we have used a QTOF Premier mass spectrometer and investigated its functionalities to obtain the best MS data, mainly in terms of mass accuracy, dynamic range and sensitivity. Different parameters that can affect mass accuracy, such as lock mass, ion abundance, spectral resolution, instrument calibration or matrix effect, have also been carefully evaluated using test compounds (mainly pesticides and antibiotics). The role of ultra-high-pressure liquid chromatography (UHPLC), especially when dealing with complex matrices, has also been tested. In addition to the mass accuracy measurements, this analyser allows the simultaneous acquisition of low and high collision energy spectra. This acquisition mode greatly enhances the reliable identification of detected compounds due to the useful (de)protonated molecule and fragment ion accurate mass information obtained when working in this mode. An in-house empirical spectral library was built for approximately 230 organic pollutants making use of QTOF MS in MS(E) mode. All the information reported in this paper is made available to the readers to facilitate screening and identification of relevant organic pollutants by QTOF MS.

  13. Suspected-target pesticide screening using gas chromatography-quadrupole time-of-flight mass spectrometry with high resolution deconvolution and retention index/mass spectrum library.

    PubMed

    Zhang, Fang; Wang, Haoyang; Zhang, Li; Zhang, Jing; Fan, Ruojing; Yu, Chongtian; Wang, Wenwen; Guo, Yinlong

    2014-10-01

    A strategy for suspected-target screening of pesticide residues in complicated matrices was exploited using gas chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS). The screening workflow followed three key steps of, initial detection, preliminary identification, and final confirmation. The initial detection of components in a matrix was done by a high resolution mass spectrum deconvolution; the preliminary identification of suspected pesticides was based on a special retention index/mass spectrum (RI/MS) library that contained both the first-stage mass spectra (MS(1) spectra) and retention indices; and the final confirmation was accomplished by accurate mass measurements of representative ions with their response ratios from the MS(1) spectra or representative product ions from the second-stage mass spectra (MS(2) spectra). To evaluate the applicability of the workflow in real samples, three matrices of apple, spinach, and scallion, each spiked with 165 test pesticides in a set of concentrations, were selected as the models. The results showed that the use of high-resolution TOF enabled effective extractions of spectra from noisy chromatograms, which was based on a narrow mass window (5 mDa) and suspected-target compounds identified by the similarity match of deconvoluted full mass spectra and filtering of linear RIs. On average, over 74% of pesticides at 50 ng/mL could be identified using deconvolution and the RI/MS library. Over 80% of pesticides at 5 ng/mL or lower concentrations could be confirmed in each matrix using at least two representative ions with their response ratios from the MS(1) spectra. In addition, the application of product ion spectra was capable of confirming suspected pesticides with specificity for some pesticides in complicated matrices. In conclusion, GC-QTOF MS combined with the RI/MS library seems to be one of the most efficient tools for the analysis of suspected-target pesticide residues

  14. Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy

    SciTech Connect

    Siketić, Zdravko; Bogdanović Radović, Ivančica; Jakšić, Milko; Popović Hadžija, Marijana; Hadžija, Mirko

    2015-08-31

    In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells.

  15. Extension of the two-dimensional mass channel cluster plot method to fast separations utilizing low thermal mass gas chromatography with time-of-flight mass spectrometry.

    PubMed

    Fitz, Brian D; Synovec, Robert E

    2016-03-24

    Implementation of a data reduction and visualization method for use with high-speed gas chromatography and time-of-flight mass spectrometry (GC-TOFMS) is reported. The method, called the "2D m/z cluster method" facilitates analyte detection, deconvolution, and identification, by accurately measuring peak widths and retention times using a fast TOFMS sampling frequency (500 Hz). Characteristics and requirements for high speed GC are taken into consideration: fast separations with narrow peak widths and high peak capacity, rapid data collection rate, and effective peak deconvolution. Transitioning from standard GC (10-60+ minute separations) to fast GC (1-10 min separations) required consideration of how to properly analyze the data. This report validates use of the 2D m/z cluster method with newly developed GC technology that produces ultra-fast separations (∼1 min) with narrow analyte peak widths. Low thermal mass gas chromatography (LTM-GC) operated at a heating rate of 250 °C/min coupled to a LECO Pegasus III TOFMS analyzed a 115 component test mixture in 120 s with peak widths-at-base, wb (4σ), of 350 ms (average) to produce a separation with a high peak capacity, nc ∼ 340 (at unit resolution Rs = 1). The 2D m/z cluster method is shown to separate overlapped analytes to a limiting Rs ∼ 0.03, so the effective peak capacity was increased nearly 30-fold to nc ∼10,000 in the 120 s separation. The method, when coupled with LTM-GC-TOFMS, is demonstrated to provide unambiguous peak rank (i.e. the number of analytes per overlapped peak in the total ion current (TIC)), by visualizing locations of pure and chromatographically overlapped m/z. Hence, peak deconvolution and identification using MCR-ALS (multivariate curve resolution - alternating least squares) is demonstrated.

  16. Assessment of Reproducibility of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Bacterial and Yeast Identification

    PubMed Central

    Westblade, Lars F.; Garner, Omai B.; MacDonald, Karen; Bradford, Constance; Pincus, David H.; Mochon, A. Brian; Jennemann, Rebecca; Manji, Ryhana; Bythrow, Maureen; Lewinski, Michael A.; Burnham, Carey-Ann D.

    2015-01-01

    Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) has revolutionized the identification of clinical bacterial and yeast isolates. However, data describing the reproducibility of MALDI-TOF MS for microbial identification are scarce. In this study, we show that MALDI-TOF MS-based microbial identification is highly reproducible and can tolerate numerous variables, including differences in testing environments, instruments, operators, reagent lots, and sample positioning patterns. Finally, we reveal that samples of bacterial and yeast isolates prepared for MALDI-TOF MS identification can be repeatedly analyzed without compromising organism identification. PMID:25926486

  17. Determination of polycyclic aromatic hydrocarbons in vegetable oils using solid-phase microextraction-comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry.

    PubMed

    Purcaro, Giorgia; Morrison, Paul; Moret, Sabrina; Conte, Lanfranco S; Marriott, Philip J

    2007-08-17

    A simple and fast solid-phase microextraction method coupled with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry was developed for analysis of polycyclic aromatic hydrocarbons in edible oil, performed directly in a hexane solution of the oil. Sampling conditions (solvent used, extraction time, extraction temperature and fiber rinsing time) were optimized by using a sample of oil fortified with a standard solution of polycyclic aromatic hydrocarbons. The method was validated by calculating linear range, correlation coefficient, accuracy, repeatability, detection limit and quantification limit. The method was applied to several oils collected from the market and directly from an olive pomace extraction plant. PMID:17597138

  18. Two-dimensional and three-dimensional dynamic imaging of live biofilms in a microchannel by time-of-flight secondary ion mass spectrometry

    SciTech Connect

    Hua, Xin; Marshall, Matthew J.; Xiong, Yijia; Ma, Xiang; Zhou, Yufan; Tucker, Abigail E.; Zhu, Zihua; Liu, Songqin; Yu, Xiao-Ying

    2015-05-01

    A vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface) was employed for in situ chemical imaging of live biofilms using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling by sputtering materials in sequential layers resulted in live biofilm spatial chemical mapping. 2D images were reconstructed to report the first 3D images of hydrated biofilm elucidating spatial and chemical heterogeneity. 2D image principal component analysis (PCA) was conducted among biofilms at different locations in the microchannel. Our approach directly visualized spatial and chemical heterogeneity within the living biofilm by dynamic liquid ToF-SIMS.

  19. Laser desorption/ionization time-of-flight mass spectrometry: A predictive tool for the lifetime of organic light emitting devices

    SciTech Connect

    Scholz, Sebastian; Meerheim, Rico; Luessem, Bjoern; Leo, Karl

    2009-01-26

    For improving the lifetime of organic light emitting devices (OLEDs), the analysis of the chemical degradation requires a deep understanding of the involved reaction pathways. We show that the dissociation reactions of phosphorescent emitters and the additional complexations with the used surrounding blocking layers are the dominant intrinsic degradation mechanisms in long living p-i-n type OLEDs. We use the laser desorption/ionization (LDI) time-of-flight mass spectrometry to correlate the laser-induced ion formation with the observed lifetime of the organic devices. The superlinear correlation between the LDI forced reactions and the lifetimes allows the prediction of the lifetime of an OLED with new materials.

  20. Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry-Based Method for Discrimination between Molecular Types of Cryptococcus neoformans and Cryptococcus gattii

    PubMed Central

    Posteraro, Brunella; Vella, Antonietta; Cogliati, Massimo; De Carolis, Elena; Florio, Ada Rita; Posteraro, Patrizia; Tortorano, Anna Maria

    2012-01-01

    We evaluated the usefulness of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) for Cryptococcus identification at the species and subspecies levels by using an in-house database of 25 reference cryptococcal spectra. Eighty-one out of the 82 Cryptococcus isolates (72 Cryptococcus neoformans and 10 Cryptococcus gattii) tested were correctly identified with respect to their molecular type designations. We showed that MALDI-TOF MS is a practicable alternative to conventional mycology or DNA-based methods. PMID:22573595

  1. Evaluating the Translational Temperature of Molecules Laser-desorbed after Online Concentration Using Multiphoton Ionization Time-of-Flight Mass Spectrometry.

    PubMed

    Miura, Shuhei; Uchimura, Tomohiro

    2016-01-01

    We describe a new technique for evaluating the translational temperature of molecules by applying online concentration via analyte adsorption/laser desorption, which is a sample-introduction technique for resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). In the present study, analyte molecules were adsorbed via a narrowed capillary tip once, and then the flow of the carrier gas containing the analyte was stopped. After laser desorption, the ion signals induced by REMPI were monitored. Finally, the translational temperature could be calculated from the velocity distribution of the desorbed molecules by applying a Maxwell distribution. PMID:27682410

  2. Rapid Identification of Positive Blood Cultures by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Using Prewarmed Agar Plates

    PubMed Central

    Bhatti, M. M.; Boonlayangoor, S.; Beavis, K. G.

    2014-01-01

    This study describes an inexpensive and straightforward method for identifying bacteria by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) directly from positive blood cultures using prewarmed agar plates. Different inoculation methods and incubation times were evaluated to determine the optimal conditions. The two methods using pelleted material from positive culture bottles performed best. In particular, the pellet streak method correctly identified 94% of the Gram negatives following 4 h of incubation and 98% of the Gram positives following 6 h of incubation. PMID:25232166

  3. Rapid identification of positive blood cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry using prewarmed agar plates.

    PubMed

    Bhatti, M M; Boonlayangoor, S; Beavis, K G; Tesic, V

    2014-12-01

    This study describes an inexpensive and straightforward method for identifying bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) directly from positive blood cultures using prewarmed agar plates. Different inoculation methods and incubation times were evaluated to determine the optimal conditions. The two methods using pelleted material from positive culture bottles performed best. In particular, the pellet streak method correctly identified 94% of the Gram negatives following 4 h of incubation and 98% of the Gram positives following 6 h of incubation.

  4. Advances in Identification of Clinical Yeast Isolates by Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

    PubMed Central

    Buchan, Blake W.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS)-based identification is being adopted by clinical laboratories for routine identification of microorganisms. To date, the majority of studies have focused on the performance and optimization of MALDI-TOF MS for the identification of bacterial isolates. We review recent literature describing the use of MALDI-TOF MS for the routine identification of a variety of yeasts and yeast-like isolates. Specific topics include the effect of optimized or streamlined extraction methods, modified scoring thresholds, expanded reference libraries, and the possibility of conducting antifungal susceptibility testing using MALDI-TOF MS. PMID:23426924

  5. Verification of a Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Method for Diagnostic Identification of High-Consequence Bacterial Pathogens

    PubMed Central

    Tracz, Dobryan M.; Antonation, Kym S.

    2015-01-01

    We examined the utility of a single matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry method for the identification of security-sensitive biological agents (risk group 3 bacterial pathogens). The goal was 2-fold: to verify a method for inclusion into our scope of accreditation, and to assess the biological safety of extractions. We developed our sample flow to include a tube-based chemical extraction, followed by filtration, before processing on MALDI-TOF MS instruments in a containment level 2 laboratory. PMID:26677252

  6. Data acquisition techniques for exploiting the uniqueness of the time-of-flight mass spectrometer: Application to sampling pulsed gas systems

    NASA Technical Reports Server (NTRS)

    Lincoln, K. A.

    1980-01-01

    Mass spectra are produced in most mass spectrometers by sweeping some parameter within the instrument as the sampled gases flow into the ion source. It is evident that any fluctuation in the gas during the sweep (mass scan) of the instrument causes the output spectrum to be skewed in its mass peak intensities. The time of flight mass spectrometer (TOFMS) with its fast, repetitive mode of operation produces spectra without skewing or varying instrument parameters and because all ion species are ejected from the ion source simultaneously, the spectra are inherently not skewed despite rapidly changing gas pressure or composition in the source. Methods of exploiting this feature by utilizing fast digital data acquisition systems, such as transient recorders and signal averagers which are commercially available are described. Applications of this technique are presented including TOFMS sampling of vapors produced by both pulsed and continuous laser heating of materials.

  7. Advances in quadrupole and time-of-flight mass spectrometry for peptide MRM based translational research analysis.

    PubMed

    Mbasu, Richard J; Heaney, Liam M; Molloy, Billy J; Hughes, Chris J; Ng, Leong L; Vissers, Johannes P C; Langridge, James I; Jones, Donald J L

    2016-08-01

    The application of unit resolution tandem quadrupole and high-resolution orthogonal acceleration ToF mass spectrometers for the quantitation and translational analysis of proteolytic peptides is described. The MS platforms were contrasted in terms of sensitivity and linear response. Moreover, the selectivity of the platforms was investigated and the effect on quantitative precision studied. Chromatographic LC conditions, including gradient length and configuration, were investigated with respect to speed/throughput, while minimizing isobaric interferences, thereby providing information with regard to practical sample cohort size limitations of LC-MS for large cohort experiments. In addition to these fundamental analytical performance metrics, precision and linear dynamic ranges were also studied. An LC-MS configuration that encompasses the best combination of throughput and analytical accuracy for translational studies was chosen, despite the MS platforms giving similar quantitative performance, and instances were identified where alternative combinations were found to be beneficial. This configuration was utilized to demonstrate that proteolytically digested nondepleted samples from heart failure patients could be classified with good discriminative power using a subset of proteins previously suggested as candidate biomarkers for cardiovascular diseases. PMID:27214876

  8. Performance evaluation of a prototype multi-bounce time-of-flight mass spectrometer in linear mode and applications in space science

    NASA Astrophysics Data System (ADS)

    Hässig, M.; Libardoni, M.; Mandt, K.; Miller, G.; Blase, R.

    2015-11-01

    Mass spectrometry is a powerful tool to measure the composition of volatile and semi volatile gases. The necessity to accurately identify and quantify unknown species lead to the requirements of a mass spectrometer as the detector of choice in most separation science and direct sample analysis situations. Advantages of time-of-flight mass spectrometry (TOFMS) are the high mass resolution, high mass range, and the measurement of the entire mass range in each extraction. The multi-bounce time-of-flight mass spectrometer (MBTOF) described in this work, takes advantage of a small footprint without sacrificing mass resolution. To achieve this, the MBTOF prototype uses a linear flight path with dual lens stacks. Ions are bounced in between the mirrors for a specified duration whereby increasing their flight time and resolution. The number of bounces can tune the resolution of the instrument. To show the minimum capabilities of the instrument and further applications of it, MBTOF was operated in linear mode. The instrument is designed for a multibounce passage of the ion optics and the focal point of the ion optics is optimized for this application, therefore the resolution in linear mode is limited. However, even in linear mode of operation, the mass resolution meets or exceeds that of a quadrupole mass spectrometer with limited power supplies required for operations. The measurements presented here are based on lab measurements of the early lab prototype MBTOF operated in a linear flight mode with low ion source extraction fields. A detailed evaluation including filament characterization, dynamic range and resolution are investigated. Further discussion involving applications on planetary missions for rocket science, coupling of MBTOF with laser thermal desorption or gas chromatography for potential organic determination in deep space are included.

  9. A multi-residue method for 17 anticoccidial drugs and ractopamine in animal tissues by liquid chromatography-tandem mass spectrometry and time-of-flight mass spectrometry.

    PubMed

    Matus, Johanna L; Boison, Joe O

    2016-05-01

    A new and sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QToF-MS) method was developed and validated for the determination and confirmation of residues of 17 anticoccidials, plus free ractopamine in poultry muscle and liver, and bovine muscle, liver, and kidney tissues. The 17 anticoccidials are lasalocid, halofuginone, narasin, monensin, semduramicin, ethopabate, robenidine, buquinolate, toltrazuril as its sulfone metabolite, maduramicin, salinomycin, diclazuril, amprolium, decoquinate, dinitolmide, clopidol, and the nicarbazin metabolite DNC (N,N1-bis(4-nitrophenyl)urea). The analytes were extracted and cleaned up within a 3-hour period by simply extracting the analytes into a solvent mixture with salts followed by centrifugation, dilution, and filtration. The validated method was used in a pilot study for the analysis of 173 samples that included quail liver, bovine kidney, liver, muscle, and horse muscle. The predominant residues found in this study were monensin, ractopamine, and lasalocid. The results of this pilot study showed that this new method is applicable to real samples, and is fit for use in a regulatory testing programme. © 2016 Her Majesty the Queen in Right of Canada. Drug Testing and Analysis. © 2016 John Wiley & Sons, Ltd. PMID:27443201

  10. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry.

    PubMed

    Martín-Ortiz, A; Salcedo, J; Barile, D; Bunyatratchata, A; Moreno, F J; Martin-García, I; Clemente, A; Sanz, M L; Ruiz-Matute, A I

    2016-01-01

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2-0.6min) and good symmetry (As: 0.8-1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40°C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315mgL(-1) for neutral oligosaccharides and from 83 to 251mgL(-1) for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO.

  11. Characterization of goat colostrum oligosaccharides by nano-liquid chromatography on chip quadrupole time-of-flight mass spectrometry and hydrophilic interaction liquid chromatography-quadrupole mass spectrometry

    PubMed Central

    Martín-Ortiz, A.; Salcedo, J.; Barile, D.; Bunyatratchata, A.; Moreno, F.J.; Martin-García, I.; Clemente, A.; Sanz, M.L.; Ruiz-Matute, A.I.

    2016-01-01

    A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2–0.6 min) and good symmetry (As: 0.8–1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1% ammonium hydroxide at 40 °C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315 mg L−1 for neutral oligosaccharides and from 83 to 251 mg L−1 for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO. PMID:26427327

  12. Isotopic Ratio Outlier Analysis of the S. cerevisiae Metabolome Using Accurate Mass Gas Chromatography/Time-of-Flight Mass Spectrometry: A New Method for Discovery.

    PubMed

    Qiu, Yunping; Moir, Robyn; Willis, Ian; Beecher, Chris; Tsai, Yu-Hsuan; Garrett, Timothy J; Yost, Richard A; Kurland, Irwin J

    2016-03-01

    Isotopic ratio outlier analysis (IROA) is a (13)C metabolomics profiling method that eliminates sample to sample variance, discriminates against noise and artifacts, and improves identification of compounds, previously done with accurate mass liquid chromatography/mass spectrometry (LC/MS). This is the first report using IROA technology in combination with accurate mass gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS), here used to examine the S. cerevisiae metabolome. S. cerevisiae was grown in YNB media, containing randomized 95% (13)C, or 5%(13)C glucose as the single carbon source, in order that the isotopomer pattern of all metabolites would mirror the labeled glucose. When these IROA experiments are combined, the abundance of the heavy isotopologues in the 5%(13)C extracts, or light isotopologues in the 95%(13)C extracts, follows the binomial distribution, showing mirrored peak pairs for the molecular ion. The mass difference between the (12)C monoisotopic and the (13)C monoisotopic equals the number of carbons in the molecules. The IROA-GC/MS protocol developed, using both chemical and electron ionization, extends the information acquired from the isotopic peak patterns for formulas generation. The process that can be formulated as an algorithm, in which the number of carbons, as well as the number of methoximations and silylations are used as search constraints. In electron impact (EI/IROA) spectra, the artifactual peaks are identified and easily removed, which has the potential to generate "clean" EI libraries. The combination of chemical ionization (CI) IROA and EI/IROA affords a metabolite identification procedure that enables the identification of coeluting metabolites, and allowed us to characterize 126 metabolites in the current study. PMID:26820234

  13. Compact Two-step Laser Time-of-Flight Mass Spectrometer for in Situ Analyses of Aromatic Organics on Planetary Missions

    NASA Technical Reports Server (NTRS)

    Getty, Stephanie; Brickerhoff, William; Cornish, Timothy; Ecelberger, Scott; Floyd, Melissa

    2012-01-01

    RATIONALE A miniature time-of-flight mass spectrometer has been adapted to demonstrate two-step laser desorption-ionization (LOI) in a compact instrument package for enhanced organics detection. Two-step LDI decouples the desorption and ionization processes, relative to traditional laser ionization-desorption, in order to produce low-fragmentation conditions for complex organic analytes. Tuning UV ionization laser energy allowed control ofthe degree of fragmentation, which may enable better identification of constituent species. METHODS A reflectron time-of-flight mass spectrometer prototype measuring 20 cm in length was adapted to a two-laser configuration, with IR (1064 nm) desorption followed by UV (266 nm) postionization. A relatively low ion extraction voltage of 5 kV was applied at the sample inlet. Instrument capabilities and performance were demonstrated with analysis of a model polycyclic aromatic hydrocarbon, representing a class of compounds important to the fields of Earth and planetary science. RESULTS L2MS analysis of a model PAH standard, pyrene, has been demonstrated, including parent mass identification and the onset o(tunable fragmentation as a function of ionizing laser energy. Mass resolution m/llm = 380 at full width at half-maximum was achieved which is notable for gas-phase ionization of desorbed neutrals in a highly-compact mass analyzer. CONCLUSIONS Achieving two-step laser mass spectrometry (L2MS) in a highly-miniature instrument enables a powerful approach to the detection and characterization of aromatic organics in remote terrestrial and planetary applications. Tunable detection of parent and fragment ions with high mass resolution, diagnostic of molecular structure, is possible on such a compact L2MS instrument. Selectivity of L2MS against low-mass inorganic salt interferences is a key advantage when working with unprocessed, natural samples, and a mechanism for the observed selectivity is presented.

  14. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of environmental organisms: the Planctomycetes paradigm.

    PubMed

    Cayrou, Caroline; Raoult, Didier; Drancourt, Michel

    2010-12-01

    We have developed a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based identification technique for Planctomycetes organisms, which are used here as bacteria of suitable diversity at genus and species level for testing resolution of the method. Planctomyces maris ATCC 29201, Planctomyces brasiliensis ATCC 49424(T) , P. brasiliensis ATCC 49425, Planctomyces limnophilus ATCC 43296(T) , Blastopirellula marina ATCC 49069(T) , Rhodopirellula baltica DSM 10527(T) and Gemmata obscuriglobus DSM 5831(T) were cultured on half-strength marine broth and agar, or alternatively on caulobacter broth and agar. The resulting pellets of organisms (liquid) or colonies (solid agar) were directly applied to a MALDI-TOF plate. This yielded a reproducible, unique protein profiles comprising 23-39 peaks ranging in size from 2403 to 12 091 Da. These peaks were unambiguously distinguished from any of the 3038 bacterial spectra in the Brüker database. Matrix-assisted laser desorption/ionization time-of-flight patterns were similar for isolates grown in solid and in liquid medium, albeit the patterns from solid growth were more easily interpretable. After the incorporation of the herein determined profiles into the Brüker database, Planctomycetes isolates were blindly identified within 10 min, with an identification score in the range of 1.8 to 2.3. Matrix-assisted laser desorption/ionization time-of-flight-based clustering of these Planctomycetes organisms was consistent with 16S rDNA-based phylogeny. However, the incorporation of additional non-Planctomycetes MALDI-TOF profiles in the analysis resulted in inconsequential clustering. In conclusion, MALDI-TOF protein profiling is a new approach for the rapid and accurate identification of cultured environmental organisms, as illustrated in this study through the analysis of Planctomycetes. PMID:23766281

  15. Fatal Nocardia farcinica Bacteremia Diagnosed by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry in a Patient with Myelodysplastic Syndrome Treated with Corticosteroids

    PubMed Central

    Moretti, Amedeo; Guercini, Francesco; Cardaccia, Angela; Furbetta, Leone; Agnelli, Giancarlo; Bistoni, Francesco; Mencacci, Antonella

    2013-01-01

    Nocardia farcinica is a Gram-positive weakly acid-fast filamentous saprophytic bacterium, an uncommon cause of human infections, acquired usually through the respiratory tract, often life-threatening, and associated with different clinical presentations. Predisposing conditions for N. farcinica infections include hematologic malignancies, treatment with corticosteroids, and any other condition of immunosuppression. Clinical and microbiological diagnoses of N. farcinica infections are troublesome, and the isolation and identification of the etiologic agent are difficult and time-consuming processes. We describe a case of fatal disseminated infection in a patient with myelodysplastic syndrome, treated with corticosteroids, in which N. farcinica has been isolated from blood culture and identified by Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry. The patient died after 18 days of hospitalization in spite of triple antimicrobial therapy. Nocardia farcinica infection should be suspected in patients with history of malignancy, under corticosteroid therapy, suffering from subacute pulmonary infection,and who do not respond to conventional antimicrobial therapy. Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry can be a valuable tool for rapid diagnosis of nocardiosis. PMID:23690786

  16. Low-molecular weight protein profiling of genetically modified maize using fast liquid chromatography electrospray ionization and time-of-flight mass spectrometry.

    PubMed

    Koc, Anna; Cañuelo, Ana; Garcia-Reyes, Juan F; Molina-Diaz, Antonio; Trojanowicz, Marek

    2012-06-01

    In this work, the use of liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC-TOFMS) has been evaluated for the profiling of relatively low-molecular weight protein species in both genetically modified (GM) and non-GM maize. The proposed approach consisted of a straightforward sample fractionation with different water and ethanol-based buffer solutions followed by separation and detection of the protein species using liquid chromatography with a small particle size (1.8 μm) C(18) column and electrospray-time-of-flight mass spectrometry detection in the positive ionization mode. The fractionation of maize reference material containing different content of transgenic material (from 0 to 5% GM) led to five different fractions (albumins, globulins, zeins, zein-like glutelins, and glutelins), all of them containing different protein species (from 2 to 52 different species in each fraction). Some relevant differences in the quantity and types of protein species were observed in the different fractions of the reference material (with different GM contents) tested, thus revealing the potential use of the proposed approach for fast protein profiling and to detect tentative GMO markers in maize.

  17. Low-molecular weight protein profiling of genetically modified maize using fast liquid chromatography electrospray ionization and time-of-flight mass spectrometry.

    PubMed

    Koc, Anna; Cañuelo, Ana; Garcia-Reyes, Juan F; Molina-Diaz, Antonio; Trojanowicz, Marek

    2012-06-01

    In this work, the use of liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC-TOFMS) has been evaluated for the profiling of relatively low-molecular weight protein species in both genetically modified (GM) and non-GM maize. The proposed approach consisted of a straightforward sample fractionation with different water and ethanol-based buffer solutions followed by separation and detection of the protein species using liquid chromatography with a small particle size (1.8 μm) C(18) column and electrospray-time-of-flight mass spectrometry detection in the positive ionization mode. The fractionation of maize reference material containing different content of transgenic material (from 0 to 5% GM) led to five different fractions (albumins, globulins, zeins, zein-like glutelins, and glutelins), all of them containing different protein species (from 2 to 52 different species in each fraction). Some relevant differences in the quantity and types of protein species were observed in the different fractions of the reference material (with different GM contents) tested, thus revealing the potential use of the proposed approach for fast protein profiling and to detect tentative GMO markers in maize. PMID:22740254

  18. Profiling analysis of low molecular weight heparins by multiple heart-cutting two dimensional chromatography with quadruple time-of-flight mass spectrometry.

    PubMed

    Ouyang, Yilan; Zeng, Yangyang; Rong, Yinxiu; Song, Yue; Shi, Lv; Chen, Bo; Yang, Xinlei; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

    2015-09-01

    Low molecular weight heparins (LMWHs) are polydisperse and microheterogenous mixtures of polysaccharides used as anticoagulant drugs. Profiling analysis is important for obtaining deeper insights into the structure of LMWHs. Previous oligosaccharide mapping methods are relatively low resolution and are unable to show an entire picture of the structural complexity of LMWHs. In the current study a profiling method was developed relying on multiple heart-cutting, two-dimensional, ultrahigh performance liquid chromatography with quadruple time-of-flight mass spectrometry. This represents an efficient, automated, and robust approach for profiling LMWHs. Using size-exclusion chromatography and ion-pairing reversed-phase chromatography in a two-dimensional separation, LMW components of different sizes and LMW components of the same size but with different charges and polarities can be resolved, providing a more complete picture of a LMWH. Structural information on each component was then obtained with quadrupole time-of-flight mass spectrometry. More than 80 and 120 oligosaccharides were observed and unambiguously assigned from the LMWHs, nadroparin and enoxaparin, respectively. This method might be useful for quality control of LMWHs and as a powerful tool for heparin-related glycomics.

  19. Identification of Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs) in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS).

    PubMed

    Strynar, Mark; Dagnino, Sonia; McMahen, Rebecca; Liang, Shuang; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol

    2015-10-01

    Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the

  20. Preliminary energy-filtering neutron imaging with time-of-flight method on PKUNIFTY: A compact accelerator based neutron imaging facility at Peking University

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Zou, Yubin; Wen, Weiwei; Lu, Yuanrong; Guo, Zhiyu

    2016-07-01

    Peking University Neutron Imaging Facility (PKUNIFTY) works on an accelerator-based neutron source with a repetition period of 10 ms and pulse duration of 0.4 ms, which has a rather low Cd ratio. To improve the effective Cd ratio and thus improve the detection capability of the facility, energy-filtering neutron imaging was realized with the intensified CCD camera and time-of-flight (TOF) method. Time structure of the pulsed neutron source was firstly simulated with Geant4, and the simulation result was evaluated with experiment. Both simulation and experiment results indicated that fast neutrons and epithermal neutrons were concentrated in the first 0.8 ms of each pulse period; meanwhile in the period of 0.8-2.0 ms only thermal neutrons existed. Based on this result, neutron images with and without energy filtering were acquired respectively, and it showed that detection capability of PKUNIFTY was improved with setting the exposure interval as 0.8-2.0 ms, especially for materials with strong moderating capability.

  1. Synopsis of a computer program designed to interface a personal computer with the fast data acquisition system of a time-of-flight mass spectrometer

    NASA Technical Reports Server (NTRS)

    Bechtel, R. D.; Mateos, M. A.; Lincoln, K. A.

    1988-01-01

    Briefly described are the essential features of a computer program designed to interface a personal computer with the fast, digital data acquisition system of a time-of-flight mass spectrometer. The instrumentation was developed to provide a time-resolved analysis of individual vapor pulses produced by the incidence of a pulsed laser beam on an ablative material. The high repetition rate spectrometer coupled to a fast transient recorder captures complete mass spectra every 20 to 35 microsecs, thereby providing the time resolution needed for the study of this sort of transient event. The program enables the computer to record the large amount of data generated by the system in short time intervals, and it provides the operator the immediate option of presenting the spectral data in several different formats. Furthermore, the system does this with a high degree of automation, including the tasks of mass labeling the spectra and logging pertinent instrumental parameters.

  2. Triple Quadrupole Versus High Resolution Quadrupole-Time-of-Flight Mass Spectrometry for Quantitative LC-MS/MS Analysis of 25-Hydroxyvitamin D in Human Serum

    NASA Astrophysics Data System (ADS)

    Geib, Timon; Sleno, Lekha; Hall, Rabea A.; Stokes, Caroline S.; Volmer, Dietrich A.

    2016-08-01

    We describe a systematic comparison of high and low resolution LC-MS/MS assays for quantification of 25-hydroxyvitamin D3 in human serum. Identical sample preparation, chromatography separations, electrospray ionization sources, precursor ion selection, and ion activation were used; the two assays differed only in the implemented final mass analyzer stage; viz. high resolution quadrupole-quadrupole-time-of-flight (QqTOF) versus low resolution triple quadrupole instruments. The results were assessed against measured concentration levels from a routine clinical chemiluminescence immunoassay. Isobaric interferences prevented the simple use of TOF-MS spectra for extraction of accurate masses and necessitated the application of collision-induced dissociation on the QqTOF platform. The two mass spectrometry assays provided very similar analytical figures of merit, reflecting the lack of relevant isobaric interferences in the MS/MS domain, and were successfully applied to determine the levels of 25-hydroxyvitamin D for patients with chronic liver disease.

  3. Isotope dilution mass spectrometry for quantitative elemental analysis of powdered samples by radiofrequency pulsed glow discharge time of flight mass spectrometry.

    PubMed

    Alvarez-Toral, Aitor; Fernandez, Beatriz; Malherbe, Julien; Claverie, Fanny; Molloy, John L; Pereiro, Rosario; Sanz-Medel, Alfredo

    2013-10-15

    In recent years particular effort is being devoted to the development of pulsed glow discharges (PGDs) for mass spectrometry because this powering operation mode could offer important ionization analytical advantages. However, the capabilities of radiofrequency (RF) PGD coupled to a time of flight mass spectrometry (ToFMS) for accurate isotope ratio measurements have not been demonstrated yet. This work is focused on investigating different time positions along the pulse profile for the accurate measurement of isotope ratios. As a result, a method has been developed for the direct and simultaneous multielement determination of trace elements in powdered geological samples by RF-PGD-ToFMS in combination with isotope dilution mass spectrometry (IDMS) as an absolute measurement method directly traceable to the International System of Units. Optimized operating conditions were 70 W of applied radiofrequency power, 250 Pa of pressure, 2 ms of pulse width and 4 ms of pulse period, being argon the plasma gas used. To homogeneously distribute the added isotopically-enriched standards, lithium borate fusion of powdered solid samples was used as sample preparation approach. In this way, Cu, Zn, Ba and Pb were successfully determined by RF-PGD-ToF(IDMS) in two NIST Standard Reference Materials (SRM 2586 and SRM 2780) representing two different matrices of geological interest (soil and rock samples). Cu, Zn, Ba and Pb concentrations determined by RF-PGD-ToF(IDMS) were well in agreement with the certified values at 95% confidence interval and precisions below 12% relative standard deviation were observed for three independent analyses. Elemental concentrations investigated were in the range of 81-5770 mg/kg, demonstrating the potential of RF-PGD-ToF(IDMS) for a sensitive, accurate and robust analysis of powdered samples.

  4. Isotope dilution mass spectrometry for quantitative elemental analysis of powdered samples by radiofrequency pulsed glow discharge time of flight mass spectrometry.

    PubMed

    Alvarez-Toral, Aitor; Fernandez, Beatriz; Malherbe, Julien; Claverie, Fanny; Molloy, John L; Pereiro, Rosario; Sanz-Medel, Alfredo

    2013-10-15

    In recent years particular effort is being devoted to the development of pulsed glow discharges (PGDs) for mass spectrometry because this powering operation mode could offer important ionization analytical advantages. However, the capabilities of radiofrequency (RF) PGD coupled to a time of flight mass spectrometry (ToFMS) for accurate isotope ratio measurements have not been demonstrated yet. This work is focused on investigating different time positions along the pulse profile for the accurate measurement of isotope ratios. As a result, a method has been developed for the direct and simultaneous multielement determination of trace elements in powdered geological samples by RF-PGD-ToFMS in combination with isotope dilution mass spectrometry (IDMS) as an absolute measurement method directly traceable to the International System of Units. Optimized operating conditions were 70 W of applied radiofrequency power, 250 Pa of pressure, 2 ms of pulse width and 4 ms of pulse period, being argon the plasma gas used. To homogeneously distribute the added isotopically-enriched standards, lithium borate fusion of powdered solid samples was used as sample preparation approach. In this way, Cu, Zn, Ba and Pb were successfully determined by RF-PGD-ToF(IDMS) in two NIST Standard Reference Materials (SRM 2586 and SRM 2780) representing two different matrices of geological interest (soil and rock samples). Cu, Zn, Ba and Pb concentrations determined by RF-PGD-ToF(IDMS) were well in agreement with the certified values at 95% confidence interval and precisions below 12% relative standard deviation were observed for three independent analyses. Elemental concentrations investigated were in the range of 81-5770 mg/kg, demonstrating the potential of RF-PGD-ToF(IDMS) for a sensitive, accurate and robust analysis of powdered samples. PMID:24054645

  5. Quantification, confirmation and screening capability of UHPLC coupled to triple quadrupole and hybrid quadrupole time-of-flight mass spectrometry in pesticide residue analysis.

    PubMed

    Grimalt, Susana; Sancho, Juan V; Pozo, Oscar J; Hernández, Félix

    2010-04-01

    The potential of three mass spectrometry (MS) analyzers (triple quadrupole, QqQ; time of flight, TOF; and quadrupole time of flight, QTOF) has been investigated and compared for quantification, confirmation and screening purposes in pesticide residue analysis of fruit and vegetable samples. For this purpose, analytical methodology for multiresidue determination of 11 pesticides, taken as a model, has been developed and validated in nine food matrices for the three mass analyzers coupled to ultra high pressure liquid chromatography. In all cases, limits of quantification around 0.01 mg/kg were reached, fulfilling the most restrictive case of baby-food analysis. Regarding absolute sensitivity, the lower limits of detection were obtained, as expected, for QqQ (100 fg), whereas slightly higher limits (300 fg) were obtained for both TOF and QTOF. Confirmative capacity of each analyzer was studied for each analyte based on the identification points (IPs) criterion, useful for a comprehensive comparison. QTOF mass analyzer showed the highest confirmatory capacity, although QqQ normally led to sufficient number of IPs, even at lower concentration levels. The potential of TOF MS was also investigated for screening purposes. To this aim, around 50 commercial fruits and vegetables samples were analyzed, searching for more than 400 pesticides. TOF MS proved to be an attractive analytical tool for rapid detection and reliable identification of a large number of pesticides thanks to the full spectrum acquisition at accurate mass with satisfactory sensitivity. This process is readily boosted when combined with specialized software packages, together with theoretical exact mass databases. Several pesticides (e.g. carbendazim in citrus and indoxacarb in grape) were detected in the samples. Further unequivocal confirmation of the identity was performed using reference standards and/or QTOF MS/MS experiments. PMID:20301091

  6. Screening and quantitation of multiclass drugs of abuse and pharmaceuticals in hair by fast liquid chromatography electrospray time-of-flight mass spectrometry.

    PubMed

    Domínguez-Romero, Juan C; García-Reyes, Juan F; Molina-Díaz, Antonio

    2011-07-15

    In this work, an automated screening method for the simultaneous identification and quantitation of 30 representative multiclass drugs (including opiates, cocaine and its main metabolite, cannabinoids, amphetamines and other stimulants in hair samples) has been developed using fast liquid-chromatography time-of-flight mass spectrometry (LC-TOFMS). The identification and quantitation of the drugs were carried out by liquid chromatography using a C(18) column (4.6×50 mm) with 1.8 μm particle size. Accurate mass measurements of ions of interest (typically [M+H](+)) by electrospray time-of-flight mass spectrometry in the positive ionization mode were used for unambiguous confirmation of the targeted species. Three sample preparation methodologies were evaluated: (a) direct methanolic extraction by sonication, (b) acidic extraction, and (c) alkaline digestion. Direct methanolic extraction showed better recoveries and cleaner extracts. The limits of detection obtained in hair matrix were as low as 5 pg mg(-1) for cocaine and cannabidiol, ranging from 5 to 75 pg mg(-1) for the studied species while the LOQ ranged from 15 to 250 pg mg(-1). The method has been applied to six hair samples from drug consumer volunteers, where the presence of at least one drug was confirmed by accurate mass measurements within 2 ppm (mass error) in most cases. The present study demonstrates the usefulness of LC-TOFMS for both screening and quantitation purposes in drug testing in hair. In addition, the possibility of non-target or a posteriori data analysis of samples or the extension of the procedure for testing for additional compounds offers interesting features for forensic analysis.

  7. Chemical and biological differentiation of three human breast cancer cell types using time-of-flight secondary ion mass spectrometry (TOF-SIMS)

    SciTech Connect

    Kulp, K S; Berman, E F; Knize, M G; Shattuck, D L; Nelson, E J; Wu, L; Montgomery, J L; Felton, J S; Wu, K J

    2006-01-09

    We use Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) to image and classify individual cells based on their characteristic mass spectra. Using statistical data reduction on the large data sets generated during TOF-SIMS analysis, similar biological materials can be differentiated based on a combination of small changes in protein expression, metabolic activity and cell structure. We apply this powerful technique to image and differentiate three carcinoma-derived human breast cancer cell lines (MCF-7, T47D and MDA-MB-231). In homogenized cells, we show the ability to differentiate the cell types as well as cellular compartments (cytosol, nuclear and membrane). These studies illustrate the capacity of TOF-SIMS to characterize individual cells by chemical composition, which could ultimately be applied to detect and identify single aberrant cells within a normal cell population. Ultimately, we anticipate characterizing rare chemical changes that may provide clues to single cell progression within carcinogenic and metastatic pathways.

  8. A rapid method for chemical fingerprint analysis of Pan Panax notoginseng powders by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    PubMed

    Liu, Peng; Yu, He-Shuil; Zhang, Li-Juan; Song, Xin-Bo; Kang, Li-Ping; Liu, Jing-Yuan; Zhang, Jie; Cao, Man; Yu, Kate; Kang, Ting-Guo; Ma, Bai-Ping

    2015-06-01

    A method coupling ultra-performance liquid chromatography (UPLC) with quadrupole time-of-flight mass spectrometer (Qtof MS) using the electrospray ionization (ESI) source was developed for the identification of the major saponins from Panax notoginseng powder (PNP). Ten different PNP samples were analyzed and evaluated for their quality by similarity evaluation and principle component analysis (PCA). Based on the accurate mass, summarized characteristic fragmentation behaviors, retention times of different types of saponins, related botanical biogenesis, and reported chromatographic behavior of saponins, fifty-one common peaks were effectively separated and identified, including 28 protopanaxadiol saponins and 18 protopanaxatriol saponins. Simultaneously, 15 significant discrepancy compounds were identified from the disqualified PNP samples. The established UPLC/Qtof MS fingerprint method was successfully applied for profiling and identifying the major saponins of PNP, providing a fast quality evaluation tool for distinguishing the authentic PNP and the adulterated products.

  9. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry of coal liquids produced during a coal liquefaction process

    SciTech Connect

    Jacqui F. Hamilton; Alistair. C. Lewis; Marcos Millan; Keith D. Bartle; Alan A. Herod; Rafael Kandiyoti

    2007-01-15

    Comprehensive two-dimensional gas chromatography (GC) coupled to time-of-flight mass spectrometry (MS) has been applied to the analysis of coal-derived liquids from the former British Coal Point-of-Ayr coal liquefaction plant. The feed to the hydrocracker and the resulting product were analyzed. The results refer almost exclusively to the plant-derived recycle solvent, known as the liquefaction solvent; the molecular mass range of the GC does not exceed that of the solvent. The method allows for the resolution of the numerous structural isomers of tetralin and methyl indan, one pair of hydrogen-donor (necessary for the dissolution of coal) and isomeric nondonor (that reduce the hydrogen donors) components of the recycle solvent. In addition, the n-alkanes that concentrate in the recycle solvent are easily observed in comparison with the results from one-dimensional GC-MS. 24 refs., 6 figs., 1 tab.

  10. Rapid Screening of Multiclass Syrup Adulterants in Honey by Ultrahigh-Performance Liquid Chromatography/Quadrupole Time of Flight Mass Spectrometry.

    PubMed

    Du, Bing; Wu, Liming; Xue, Xiaofeng; Chen, Lanzhen; Li, Yi; Zhao, Jing; Cao, Wei

    2015-07-29

    Honey adulteration with sugar syrups is a widespread problem. Several types of syrups have been used in honey adulteration, and there is no available method that can simultaneously detect all of these adulterants. In this study, we generated a small-scale database containing the specific chromatographic and mass spectrometry information on sugar syrup markers and developed a simple, rapid, and effective ultrahigh-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) method for the detection of adulterated honey. Corn syrup, high-fructose corn syrup, inverted syrup, and rice syrup were used as honey adulterants; polysaccharides, difructose anhydrides, and 2-acetylfuran-3-glucopyranoside were used as detection markers. The presence of 10% sugar syrup in honey could be easily detected in <30 min using the developed method. The results revealed that UHPLC/Q-TOF-MS was simple and rapid. PMID:26151590

  11. Rapid Screening of Multiclass Syrup Adulterants in Honey by Ultrahigh-Performance Liquid Chromatography/Quadrupole Time of Flight Mass Spectrometry.

    PubMed

    Du, Bing; Wu, Liming; Xue, Xiaofeng; Chen, Lanzhen; Li, Yi; Zhao, Jing; Cao, Wei

    2015-07-29

    Honey adulteration with sugar syrups is a widespread problem. Several types of syrups have been used in honey adulteration, and there is no available method that can simultaneously detect all of these adulterants. In this study, we generated a small-scale database containing the specific chromatographic and mass spectrometry information on sugar syrup markers and developed a simple, rapid, and effective ultrahigh-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) method for the detection of adulterated honey. Corn syrup, high-fructose corn syrup, inverted syrup, and rice syrup were used as honey adulterants; polysaccharides, difructose anhydrides, and 2-acetylfuran-3-glucopyranoside were used as detection markers. The presence of 10% sugar syrup in honey could be easily detected in <30 min using the developed method. The results revealed that UHPLC/Q-TOF-MS was simple and rapid.

  12. High-resolution time-of-flight mass spectrometry fingerprinting of metabolites from cecum and distal colon contents of rats fed resistant starch

    SciTech Connect

    Anderson, Timothy J.; Jones, Roger W.; Ai, Yongfeng; Houk, Robert S.; Jane, Jay-lin; Zhao, Yinsheng; Birt, Diane F.; McClelland, John F.

    2013-12-04

    Time-of-flight mass spectrometry along with statistical analysis was utilized to study metabolic profiles among rats fed resistant starch (RS) diets. Fischer 344 rats were fed four starch diets consisting of 55 % (w/w, dbs) starch. A control starch diet consisting of corn starch was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. A subgroup received antibiotic treatment to determine if perturbations in the gut microbiome were long lasting. A second subgroup was treated with azoxymethane (AOM), a carcinogen. At the end of the 8-week study, cecal and distal colon content samples were collected from the sacrificed rats. Metabolites were extracted from cecal and distal colon samples into acetonitrile. The extracts were then analyzed on an accurate-mass time-of-flight mass spectrometer to obtain their metabolic profile. The data were analyzed using partial least-squares discriminant analysis (PLS-DA). The PLS-DA analysis utilized a training set and verification set to classify samples within diet and treatment groups. PLS-DA could reliably differentiate the diet treatments for both cecal and distal colon samples. The PLS-DA analyses of the antibiotic and no antibiotic-treated subgroups were well classified for cecal samples and modestly separated for distal colon samples. PLS-DA analysis had limited success separating distal colon samples for rats given AOM from those not treated; the cecal samples from AOM had very poor classification. Mass spectrometry profiling coupled with PLS-DA can readily classify metabolite differences among rats given RS diets.

  13. The performance and the characterization of laser ablation aerosol particle time-of-flight mass spectrometry (LAAP-ToF-MS)

    NASA Astrophysics Data System (ADS)

    Gemayel, Rachel; Hellebust, Stig; Temime-Roussel, Brice; Hayeck, Nathalie; Van Elteren, Johannes T.; Wortham, Henri; Gligorovski, Sasho

    2016-05-01

    Hyphenated laser ablation-mass spectrometry instruments have been recognized as useful analytical tools for the detection and chemical characterization of aerosol particles. Here we describe the performances of a laser ablation aerosol particle time-of-flight mass spectrometer (LAAP-ToF-MS) which was designed for aerodynamic particle sizing using two 405 nm scattering lasers and characterization of the chemical composition of single aerosol particle via ablation/ionization by a 193 nm excimer laser and detection in a bipolar time-of-flight mass spectrometer with a mass resolving power of m/Δm > 600.

    We describe a laboratory based optimization strategy for the development of an analytical methodology for characterization of atmospheric particles using the LAAP-ToF-MS instrument in combination with a particle generator, a differential mobility analyzer and an optical particle counter. We investigated the influence of particle number concentration, particle size and particle composition on the detection efficiency. The detection efficiency is a product of the scattering efficiency of the laser diodes and the ionization efficiency or hit rate of the excimer laser. The scattering efficiency was found to vary between 0.6 and 1.9 % with an average of 1.1 %; the relative standard deviation (RSD) was 17.0 %. The hit rate exhibited good repeatability with an average value of 63 % and an RSD of 18 %. In addition to laboratory tests, the LAAP-ToF-MS was used to sample ambient air during a period of 6 days at the campus of Aix-Marseille University, situated in the city center of Marseille, France. The optimized LAAP-ToF-MS methodology enables high temporal resolution measurements of the chemical composition of ambient particles, provides new insights into environmental science, and a new investigative tool for atmospheric chemistry and physics, aerosol science and health impact studies.

  14. Characterization of chemical constituents in Zhi-Zi-Da-Huang decoction by ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    PubMed

    Zhu, Heyun; Yin, Ran; Han, Fei; Guan, Jiao; Zhang, Xiaoshu; Mao, Xinjuan; Zhao, Longshan; Li, Qing; Hou, Xiaohong; Bi, Kaishun

    2014-12-01

    A sensitive and reliable ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method was established to separate and identify the chemical constituents of Zhi-Zi-Da-Huang decoction, a classic traditional Chinese medicine formula. The chromatographic separation was achieved on a Shim-pack XR-ODS C18 column (75 × 3.0 mm, 2.2 μm) using a gradient elution program. The detection was performed on a Waters Xevo G2 Q-TOF mass spectrometer equipped with electrospray ionization source in both positive and negative modes. With the optimized conditions, a total of 82 compounds were identified or tentatively characterized. Of the 82 compounds, 21 compounds were identified by comparing the retention time and MS data with reference standards, the rest were characterized by analyzing MS data and retrieving the reference literature. In addition, 31 compounds were identified from Gardenia jasminoides Ellis, ten compounds were identified from Rheum palmatum L., 33 compounds were identified from Citrus aurantium L., and eight compounds were identified from Sojae Semen Praeparatum. Results indicated that iridoids, anthraquinones, flavonoids, isoflavonoids, coumarins, glycosides of crocetin, monoterpenoids, and organic acids were major constituents in Zhi-Zi-Da-Huang decoction. It is concluded that the developed ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method with high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents of Zhi-Zi-Da-Huang decoction, and the analysis provides a helpful chemical basis for further research on Zhi-Zi-Da-Huang decoction. PMID:25195935

  15. Characterization of chemical constituents in Zhi-Zi-Da-Huang decoction by ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

    PubMed

    Zhu, Heyun; Yin, Ran; Han, Fei; Guan, Jiao; Zhang, Xiaoshu; Mao, Xinjuan; Zhao, Longshan; Li, Qing; Hou, Xiaohong; Bi, Kaishun

    2014-12-01

    A sensitive and reliable ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method was established to separate and identify the chemical constituents of Zhi-Zi-Da-Huang decoction, a classic traditional Chinese medicine formula. The chromatographic separation was achieved on a Shim-pack XR-ODS C18 column (75 × 3.0 mm, 2.2 μm) using a gradient elution program. The detection was performed on a Waters Xevo G2 Q-TOF mass spectrometer equipped with electrospray ionization source in both positive and negative modes. With the optimized conditions, a total of 82 compounds were identified or tentatively characterized. Of the 82 compounds, 21 compounds were identified by comparing the retention time and MS data with reference standards, the rest were characterized by analyzing MS data and retrieving the reference literature. In addition, 31 compounds were identified from Gardenia jasminoides Ellis, ten compounds were identified from Rheum palmatum L., 33 compounds were identified from Citrus aurantium L., and eight compounds were identified from Sojae Semen Praeparatum. Results indicated that iridoids, anthraquinones, flavonoids, isoflavonoids, coumarins, glycosides of crocetin, monoterpenoids, and organic acids were major constituents in Zhi-Zi-Da-Huang decoction. It is concluded that the developed ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method with high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents of Zhi-Zi-Da-Huang decoction, and the analysis provides a helpful chemical basis for further research on Zhi-Zi-Da-Huang decoction.

  16. Broad-spectrum drug screening of meconium by liquid chromatography with tandem mass spectrometry and time-of-flight mass spectrometry.

    PubMed

    Ristimaa, Johanna; Gergov, Merja; Pelander, Anna; Halmesmäki, Erja; Ojanperä, Ilkka

    2010-09-01

    Analysis of the major drugs of abuse in meconium has been established in clinical practice for detecting fetal exposure to illicit drugs, particularly for the ready availability of the sample and ease of collection from diapers, compared with neonatal hair and urine. Very little is known about the occurrence and detection possibilities of therapeutic and licit drugs in meconium. Meconium specimens (n = 209) were collected in delivery hospitals, from infants of mothers who were suspected to be drug abusers. A targeted analysis method by liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) was developed for abused drugs: amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, morphine, codeine, 6-monoacetylmorphine, oxycodone, methadone, tramadol, buprenorphine, and norbuprenorphine. A separate LC-MS/MS method was developed for 11-nor-∆(9)-tetrahydrocannabinol-9-carboxylic acid. A screening method based on LC coupled to time-of-flight MS was applied to a broad spectrum of drugs. As a result, a total of 77 different compounds were found. The main drug findings in meconium were as follows: local anesthetics 82.5% (n = 172), nicotine or its metabolites 61.5% (n = 129), opioids 48.5% (n = 101), stimulants 21.0% (n = 44), hypnotics and sedatives 19.0% (n = 40), antidepressants 18.0% (n = 38), antipsychotics 5.5% (n = 11), and cannabis 3.0% (n = 5). By revealing drugs and metabolites beyond the ordinary scope, the present procedure helps the pediatrician in cases where maternal denial is strong but the infant seems to suffer from typical drug-withdrawal symptoms. Intrapartum drug administration cannot be differentiated from gestational drug use by meconium analysis, which affects the interpretation of oxycodone, tramadol, fentanyl, pethidine, and ephedrine findings. PMID:20617307

  17. A high-performance multiple-reflection time-of-flight mass spectrometer and isobar separator for the research with exotic nuclei

    NASA Astrophysics Data System (ADS)

    Dickel, T.; Plaß, W. R.; Becker, A.; Czok, U.; Geissel, H.; Haettner, E.; Jesch, C.; Kinsel, W.; Petrick, M.; Scheidenberger, C.; Simon, A.; Yavor, M. I.

    2015-03-01

    A novel multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) and isobar separator for the research with exotic nuclides at low-energy rare isotope beam facilities has been developed, commissioned and characterized. It can be used (i) as broadband mass spectrometer with medium resolution, (ii) as highly accurate mass spectrometer for direct mass measurements and (iii) as high-resolution mass separator. The device features a worldwide unique combination of performance characteristics: a mass resolving power of 600,000 (FWHM), a mass measurement accuracy of ~10-7, large ion capacities in excess of 106 ions per second, a transmission efficiency of up to 70%, single-ion sensitivity, and cycle frequencies of up to 400 Hz have been achieved. The spatial separation of close-lying isobars with an intensity ratio of 200:1 and a binding energy difference as small as 4 MeV has been demonstrated. The MR-TOF-MS is ideally suited for experiments with rare and very short-lived nuclei at present and future in-flight, ISOL or IGISOL facilities, such as the FRS Ion-Catcher and SHIP/SHIPTRAP at GSI, TITAN at TRIUMF, IGISOL at the University of Jyväskylä and the Low-Energy Branch of the Super-FRS at FAIR.

  18. Main differences between volatiles of sparkling and base wines accessed through comprehensive two dimensional gas chromatography with time-of-flight mass spectrometric detection and chemometric tools.

    PubMed

    Welke, Juliane Elisa; Zanus, Mauro; Lazzarotto, Marcelo; Pulgati, Fernando Hepp; Zini, Cláudia Alcaraz

    2014-12-01

    The main changes in the volatile profile of base wines and their corresponding sparkling wines produced by traditional method were evaluated and investigated for the first time using headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection (GC×GC/TOFMS) and chemometric tools. Fisher ratios helped to find the 119 analytes that were responsible for the main differences between base and sparkling wines and principal component analysis explained 93.1% of the total variance related to the selected 78 compounds. It was also possible to observe five subclusters in base wines and four subclusters in sparkling wines samples through hierarchical cluster analysis, which seemed to have an organised distribution according to the regions where the wines came from. Twenty of the most important volatile compounds co-eluted with other components and separation of some of them was possible due to GC×GC/TOFMS performance.

  19. Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Blood Isolates of Vibrio Species

    PubMed Central

    Cheng, Wern-Cherng; Jan, I-Shiow; Chen, Jong-Min; Teng, Shih-Hua; Teng, Lee-Jene; Sheng, Wang-Huei; Ko, Wen-Chien

    2015-01-01

    Among 56 blood isolates of Vibrio species identified by sequencing analysis of 16S rRNA and rpoB genes, the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system correctly identified all isolates of Vibrio vulnificus (n = 20), V. parahaemolyticus (n = 2), and V. fluvialis (n = 1) but none of the isolates of serogroup non-O1/O139 (non-serogroup O1, non-O139) V. cholerae (n = 33) to the species level. All of these serogroup non-O1/O139 V. cholerae isolates were correctly identified using the newly created MALDI-TOF MS database. PMID:25740773

  20. Application of ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to identify curcumin metabolites produced by human intestinal bacteria.

    PubMed

    Lou, Yan; Zheng, Jinqi; Hu, Haihong; Lee, Jun; Zeng, Su

    2015-03-15

    Curcumin, a yellow pigment derived from the rhizomes of Curcuma longa Linn, is a natural antioxidant that exhibits a variety of pharmacological activities and therapeutic properties. However, as curcumin is generally conjugated when absorbed through the intestine, free curcumin is present at extremely low levels in the body. Thus, curcumin metabolites are presumed to be responsible for curcumin bioactivity. In this study, we describe a strategy using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF MS) with automated data analysis software (MetaboLynx(XS)) for rapid analysis of the metabolic profile of curcumin in human intestinal flora. The results show that curcumin undergoes extensive phase I and phase II metabolism. A total of 23 curcumin metabolites were detected and identified in vitro. Furthermore, we identified a number of novel metabolic pathways of curcumin in the human intestinal microflora system. PMID:25658514

  1. Differentiation of Spores of Bacillus Subtilis Grown in Different Media by Elemental Characterization using Time-of-Flight Secondary Ion Mass Spectrometry

    SciTech Connect

    Cliff, John B.; Jarman, Kristin H.; Valentine, Nancy B.; Golledge, Stephen; Gaspar, Dan J.; Wunschel, David S.; Wahl, Karen L.

    2005-11-01

    We demonstrate the use of time of flight secondary ion mass spectrometry (ToF-SIMS) to infer the medium in which Bacillus subtilis spores were grown based on elemental signatures of the spores. Triplicate culture replicates grown in each of four different media were analyzed to obtain ToF-SIMS signatures comprised of 16 elemental intensities. The signatures were analyzed using ANOVA and principal components analysis (PCA). Confusion matrices constructed using nearest neighbor classification of the PCA scores confirmed the predictive utility of ToF-SIMS elemental signatures in identifying sporulation media. Application of this method will be of use in microbial forensics, and may also prove useful in the areas of food microbiology and astrobiology.

  2. Profiling of nonvolatiles in whiskeys using ultra high pressure liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS).

    PubMed

    Collins, Thomas S; Zweigenbaum, Jerry; Ebeler, Susan E

    2014-11-15

    Commercial samples of 63 American whiskeys, including bourbon whiskeys, Tennessee whiskeys, rye whiskeys and other blended whiskeys were analysed using ultra high pressure liquid chromatography (UHPLC) coupled with quadrupole time-of-flight (QTOF) mass spectrometry (MS). The non-volatile composition of the whiskeys was used to model differences among the samples using discriminant analysis. The blended American whiskeys were readily distinguished from the remaining types. Additionally, most Tennessee whiskeys could be differentiated from bourbon and rye whiskeys. Similarly, younger (<4 years old) and older (>8 years old) whiskeys could be separated. The compounds important for differentiating among these whiskeys included wood derived phenolic compounds, lignan derived compounds and several C8 and larger lipids. A number of additional compounds differentiated the whiskeys but could not be identified using MS and MS/MS data alone.

  3. Structural elucidation of biologically active neomycin N-octyl derivatives in a regioisomeric mixture by means of liquid chromatography/ion trap time-of-flight mass spectrometry.

    PubMed

    Giera, Martin; de Vlieger, Jon S B; Lingeman, Henk; Irth, Hubertus; Niessen, Wilfried M A

    2010-05-30

    Structural elucidation of six regioisomers of mono-N-octyl derivatized neomycin is achieved using MS(n) (up to n = 4) on an ion trap time-of-flight (IT-TOF) instrument equipped with electrospray ionization. The mixture of six derivatized neomycin analogues was generated by reductive amination in a shotgun synthetic approach. In parallel to the liquid chromatography/mass spectrometry (LC/MS) detection, the antibacterial activity of the neomycin regioisomers was tested by post-column addition of buffer and bacterial inocula, subsequent microfractionation of the resulting mixture, incubation, and finally a chemiluminescence-based bioactivity measurement based on the production of bacterial ATP. The MS-based high-resolution screening approach described can be applied in medicinal chemistry to help in designing and producing new antibiotic substances, which is particularly challenging due to the high functionality of most antibiotic substances, therefore requiring advanced (hyphenated) separation and detection techniques for compound mixtures.

  4. Use of comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry for the characterization of biodegradation and unresolved complex mixtures in petroleum

    NASA Astrophysics Data System (ADS)

    Tran, Tin C.; Logan, Graham A.; Grosjean, Emmanuelle; Ryan, Danielle; Marriott, Philip J.

    2010-11-01

    A comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC/TOFMS) method has been developed for separation of a series of petroleum samples using a polar/non-polar column set configuration. Groups of oils were selected to provide samples from the same oil family to assist in comparison of compositional changes during biodegradation. The groups also represented different sources and ages to allow an assessment of the application of GC × GC for the differentiation of oil source, as well as fluid history. The increased resolution and separation afforded by the GC × GC technique provides more complete compositional information on complex biodegraded oil samples than one-dimensional GC, and improves the ability to study biodegradation trends. Among the components identified, it is proposed that alkyl-decahydronaphthalenes constitute a significant contribution to the UCM.

  5. Alkaloid profiling of the traditional Chinese medicine Rhizoma corydalis using high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry

    PubMed Central

    Sun, Mingqian; Liu, Jianxun; Lin, Chengren; Miao, Lan; Lin, Li

    2014-01-01

    Since alkaloids are the major active constituents of Rhizoma corydalis (RC), a convenient and accurate analytical method is needed for their identification and characterization. Here we report a method to profile the alkaloids in RC based on liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (LC–Q-TOF-MS/MS). A total of 16 alkaloids belonging to four different classes were identified by comparison with authentic standards. The fragmentation pathway of each class of alkaloid was clarified and their differences were elucidated. Furthermore, based on an analysis of fragmentation pathways and alkaloid profiling, a rapid and accurate method for the identification of unknown alkaloids in RC is proposed. The method could also be useful for the quality control of RC. PMID:26579385

  6. Alkaloid profiling of the traditional Chinese medicine Rhizoma corydalis using high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry.

    PubMed

    Sun, Mingqian; Liu, Jianxun; Lin, Chengren; Miao, Lan; Lin, Li

    2014-06-01

    Since alkaloids are the major active constituents of Rhizoma corydalis (RC), a convenient and accurate analytical method is needed for their identification and characterization. Here we report a method to profile the alkaloids in RC based on liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). A total of 16 alkaloids belonging to four different classes were identified by comparison with authentic standards. The fragmentation pathway of each class of alkaloid was clarified and their differences were elucidated. Furthermore, based on an analysis of fragmentation pathways and alkaloid profiling, a rapid and accurate method for the identification of unknown alkaloids in RC is proposed. The method could also be useful for the quality control of RC.

  7. A Metabolomics Profiling Study in Hand-Foot-and-Mouth Disease and Modulated Pathways of Clinical Intervention Using Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry

    PubMed Central

    Lu, Cheng; Liu, Xinru; Ding, Xiaorong; Chen, Xiao; Fan, Haiwei; Liu, Yunqiang; Xie, Ning; Tan, Yong; Ko, Joshua; Zhang, Weidong; Lu, Aiping

    2013-01-01

    Hand-foot-and-mouth disease (HFMD), with poorly understood pathogenesis, has become a major public health threat across Asia Pacific. In order to characterize the metabolic changes of HFMD and to unravel the regulatory role of clinical intervention, we have performed a metabolomics approach in a clinical trial. In this study, metabolites profiling was performed by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) platform from the HFMD clinical patient samples. The outcome of this study suggested that 31 endogenous metabolites were mainly involved and showed marked perturbation in HFMD patients. In addition, combination therapy intervention showed normalized tendency in HFMD patients in differential pathway. Taken together, these results indicate that metabolomics approach can be used as a complementary tool for the detection and the study of the etiology of HFMD. PMID:23533509

  8. Characterization of volatile components in four vegetable oils by headspace two-dimensional comprehensive chromatography time-of-flight mass spectrometry.

    PubMed

    Hu, Wei; Zhang, Liangxiao; Li, Peiwu; Wang, Xiupin; Zhang, Qi; Xu, Baocheng; Sun, Xiaoman; Ma, Fei; Ding, Xiaoxia

    2014-11-01

    Edible oil adulteration is the biggest source of food fraud all over the world. Since characteristic aroma is an important quality criterion for edible oils, we analyzed volatile organic compounds (VOCs) in four edible vegetable oils (soybean, peanut, rapeseed, and sunflower seed oils) by headspace comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (Headspace-GC×GC-TOFMS) in this study. After qualitative and quantitative analysis of VOCs, we used unsupervised (PCA) and supervised (Random forests) multivariate statistical methods to build a classification model for the four edible oils. The results indicated that the four edible oils had their own characteristic VOCs, which could be used as markers to completely classify these four edible oils into four groups.

  9. Comprehensive metabolite profiling of Plantaginis Semen using ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique.

    PubMed

    Wang, Dandan; Qi, Meng; Yang, Qiming; Tong, Renchao; Wang, Rui; Bligh, S W Annie; Yang, Li; Wang, Zhengtao

    2016-05-01

    Plantaginis Semen is commonly used in traditional medicine to treat edema, hypertension, and diabetes. The commercially available Plantaginis Semen in China mainly comes from three species. To clarify the chemical composition and distinct different species of Plantaginis Semen, we established a metabolite profiling method based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique. A total of 108 compounds, including phenylethanoid glycosides, flavonoids, guanidine derivatives, terpenoids, organic acids, and fatty acids, were identified from Plantago asiatica L., P. depressa Willd., and P. major L. Results showed significant differences in chemical components among the three species, particularly flavonoids. This study is the first to provide a comprehensive chemical profile of Plantaginis Semen, which could be involved into the quality control, medication guide, and developing new drug of Plantago seeds.

  10. Determination of emerging contaminants in wastewater utilizing comprehensive two-dimensional gas-chromatography coupled with time-of-flight mass spectrometry.

    PubMed

    Prebihalo, Sarah; Brockman, Adrienne; Cochran, Jack; Dorman, Frank L

    2015-11-01

    An analytical method for identification of emerging contaminants of concern, such as pesticides and organohalogens has been developed and utilized for true discovery-based analysis. In order to achieve the level of sensitivity and selectivity necessary for detecting compounds in complex samples, comprehensive gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) was utilized to analyze wastewater samples obtained from the Pennsylvania State University wastewater treatment facility (WWTF). Determination of emerging contaminants through a process of combining samples which represent "normal background" and comparing this to new samples was developed. Results show the presence of halogenated benzotriazoles in wastewater samples as well as soil samples from Pennsylvania State University agricultural fields. The trace levels of chlorinated benzotriazoles observed in the monitoring wells present on the property indicate likely environmental degradation of the chlorinated benzotriazoles. Preliminary investigation of environmental fate of the substituted benzotriazoles indicates their likely degradation into phenol; an Environmental Protection Agency (USEPA) priority pollutant.

  11. Comprehensive metabolite profiling of Plantaginis Semen using ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique.

    PubMed

    Wang, Dandan; Qi, Meng; Yang, Qiming; Tong, Renchao; Wang, Rui; Bligh, S W Annie; Yang, Li; Wang, Zhengtao

    2016-05-01

    Plantaginis Semen is commonly used in traditional medicine to treat edema, hypertension, and diabetes. The commercially available Plantaginis Semen in China mainly comes from three species. To clarify the chemical composition and distinct different species of Plantaginis Semen, we established a metabolite profiling method based on ultra high performance liquid chromatography with electrospray ionization quadrupole time-of-flight tandem mass spectrometry coupled with elevated energy technique. A total of 108 compounds, including phenylethanoid glycosides, flavonoids, guanidine derivatives, terpenoids, organic acids, and fatty acids, were identified from Plantago asiatica L., P. depressa Willd., and P. major L. Results showed significant differences in chemical components among the three species, particularly flavonoids. This study is the first to provide a comprehensive chemical profile of Plantaginis Semen, which could be involved into the quality control, medication guide, and developing new drug of Plantago seeds. PMID:27030316

  12. Challenges in implementing a screening method for veterinary drugs in milk using liquid chromatography quadrupole time-of-flight mass spectrometry.

    PubMed

    Turnipseed, Sherri B; Lohne, Jack J; Storey, Joseph M; Andersen, Wendy C; Young, Susan L; Carr, Justin R; Madson, Mark R

    2014-04-30

    High resolution mass spectrometry (HRMS) is a valuable tool for the analysis of chemical contaminants in food. Our laboratory has successfully developed methods to screen for veterinary drug residues using liquid chromatography quadrupole time-of-flight (Q-TOF). There have been, however, significant challenges as methods are transferred from the development stage to routine regulatory analysis. Having experimental retention time and product ion information for analytes greatly facilitates the ability to determine if residues found by the HRMS searching software are false detects. These data were collected for over 200 veterinary drug residues using LC Q-TOF MS. The screening levels of detection for over 150 veterinary drug residues in milk were determined, and over half of those tested can be detected at concentrations of 10 ng/mL or less; 72% can be found in milk when present at 100 ng/mL. Tentative identification of the product ions from these analytes is also presented. PMID:24432774

  13. Characterization of organic gunshot residues in lead-free ammunition using a new sample collection device for liquid chromatography-quadrupole time-of-flight mass spectrometry.

    PubMed

    Benito, Sandra; Abrego, Zuriñe; Sánchez, Alicia; Unceta, Nora; Goicolea, M Aranzazu; Barrio, Ramón J

    2015-01-01

    The identification of characteristic organic gunshot residues (OGSR) provides conclusive evidence in the elucidation of elemental profiles when lead-free ammunition is fired. OGSR also prevents false negatives. Toward this aim, a quick and efficient method based on liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF) was developed to detect and identify 18 gunpowder additives in gunshot residues (GSR). The unequivocal identification of target analytes was assured by using MS/MS mode. Swabs were compared with home-modified tape lift supports covered with a PTFE layer to determine the better sampling technique. The modified tape lift provided better extraction recoveries and enabled the analysis of inorganic and organic GSR simultaneously. The developed method was applied to the analysis of GSR from four different lead-free ammunitions. Diphenylamine and its nitrated degradation products and centralites were identified in all samples, providing strong evidence of GSR.

  14. Localization of ginsenosides in the rhizome and root of Panax ginseng by laser microdissection and liquid chromatography-quadrupole/time of flight-mass spectrometry.

    PubMed

    Liang, Zhitao; Chen, Yujie; Xu, Liang; Qin, Minjian; Yi, Tao; Chen, Hubiao; Zhao, Zhongzhen

    2015-02-01

    The root and rhizome of Panax ginseng C.A. Mey, known as ginseng, is a commonly used medicinal plant. Ginsenosides are the major active components responsible for the tonic effects of this herb. Here, the combination of laser microdissection and ultra-high performance liquid chromatography quadrupole/time of flight-mass spectrometry (UHPLC-QTOF-MS) was applied to investigate the localization of ginsenosides in root and rhizome of P. ginseng. Five kinds of tissue cells were separated from the rhizome, main root and branch root of ginseng. Fifty-nine ginsenosides were identified and the results showed that the cork contained more kinds of ginsenosides than did the cortex, phloem, xylem and resin canals. It is interesting that the phloem, xylem and resin canals from branch root contained a greater number of ginsenosides than did from main root. This study provides solid evidence on the accumulation of ginsenosides in cork, cortex, phloem and xylem.

  15. Preparation of porous styrenics-based monolithic layers for thin layer chromatography coupled with matrix-assisted laser-desorption/ionization time-of-flight mass spectrometric detection.

    PubMed

    Lv, Yongqin; Lin, Zhixing; Tan, Tianwei; Svec, Frantisek

    2013-11-01

    Monolithic 50 μm thin poly(4-methylstyrene-co-chloromethylstyrene-co-divinylbenzene) layers attached to 6.0 cm × 3.3 cm glass plates have been prepared, using a thermally initiated polymerization process. These layers had a well-defined porous structure with a globular morphology demonstrated with SEM images and exhibited superhydrophobic properties characterized with a water contact angle of 157°. They were then used for thin-layer chromatography of peptides and proteins fluorescently labeled with fluorescamine. The spots of individual separated compounds were visualized using UV light, and their identities were confirmed with a matrix-assisted laser desorption/ionization time of flight mass spectrometry. The presence of chloromethylstyrene units in the polymer enabled hypercrosslinking via a Friedel-Crafts alkylation reaction, and led to monoliths with much larger surface areas, which were suitable for separations of small dye molecules.

  16. Profiling of nonvolatiles in whiskeys using ultra high pressure liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS).

    PubMed

    Collins, Thomas S; Zweigenbaum, Jerry; Ebeler, Susan E

    2014-11-15

    Commercial samples of 63 American whiskeys, including bourbon whiskeys, Tennessee whiskeys, rye whiskeys and other blended whiskeys were analysed using ultra high pressure liquid chromatography (UHPLC) coupled with quadrupole time-of-flight (QTOF) mass spectrometry (MS). The non-volatile composition of the whiskeys was used to model differences among the samples using discriminant analysis. The blended American whiskeys were readily distinguished from the remaining types. Additionally, most Tennessee whiskeys could be differentiated from bourbon and rye whiskeys. Similarly, younger (<4 years old) and older (>8 years old) whiskeys could be separated. The compounds important for differentiating among these whiskeys included wood derived phenolic compounds, lignan derived compounds and several C8 and larger lipids. A number of additional compounds differentiated the whiskeys but could not be identified using MS and MS/MS data alone. PMID:24912715

  17. Rapid inactivation of Mycobacterium and nocardia species before identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Dunne, W Michael; Doing, Kirk; Miller, Elizabeth; Miller, Eric; Moreno, Erik; Baghli, Mehdi; Mailler, Sandrine; Girard, Victoria; van Belkum, Alex; Deol, Parampal

    2014-10-01

    The identification of mycobacteria outside biocontainment facilities requires that the organisms first be rendered inactive. Exposure to 70% ethanol (EtOH) either before or after mechanical disruption was evaluated in order to establish a safe, effective, and rapid inactivation protocol that is compatible with identification of Mycobacterium and Nocardia species using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A combination of 5 min of bead beating in 70% EtOH followed by a 10-min room temperature incubation period was found to be rapidly bactericidal and provided high-quality spectra compared to spectra obtained directly from growth on solid media. The age of the culture, the stability of the refrigerated or frozen lysates, and freeze-thaw cycles did not adversely impact the quality of the spectra or the identification obtained.

  18. Microbial Typing by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry: Do We Need Guidance for Data Interpretation?

    PubMed Central

    van Belkum, Alex; Goering, Richard V.; Girard, Victoria; Welker, Martin; Van Nuenen, Marc; Pincus, David H.; Arsac, Maud; Durand, Géraldine

    2014-01-01

    The integration of matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) in clinical microbiology has revolutionized species identification of bacteria, yeasts, and molds. However, beyond straightforward identification, the method has also been suggested to have the potential for subspecies-level or even type-level epidemiological analyses. This minireview explores MALDI-TOF MS-based typing, which has already been performed on many clinically relevant species. We discuss the limits of the method's resolution and we suggest interpretative criteria allowing valid comparison of strain-specific data. We conclude that guidelines for MALDI-TOF MS-based typing can be developed along the same lines as those used for the interpretation of data from pulsed-field gel electrophoresis (PFGE). PMID:25056329

  19. Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry.

    PubMed

    Dorfner, Ralph; Ferge, Thomas; Kettrup, Antonius; Zimmermann, Ralf; Yeretzian, Chahan

    2003-09-10

    The formation of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting was monitored in real-time, using resonance enhanced multiphoton ionization and time-of-flight mass spectrometry. A model is proposed, based on two connected reaction channels. One channel, termed the "low activation energy" channel, consists of ester hydrolysis of 5-FQA followed by decarboxylation of the ferulic acid to form 4-vinylguaiacol, and finally polymerization at the vinyl group to form partly insoluble polymers (coffee melanoidins). The second "high activation energy" channel opens up once the beans have reached higher temperatures. It leads to formation of guaiacol, via oxidation of 4-vinylguaiacol, and subsequently to phenol and other phenolic VOCs. This work aims at developing strategies to modify the composition of coffee flavor compounds based on the time-temperature history during roasting. PMID:12952431

  20. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry reveals the correlation between chemical compounds in Japanese sake and its organoleptic properties.

    PubMed

    Takahashi, Kei; Kabashima, Fumie; Tsuchiya, Fumihiko

    2016-03-01

    Japanese sake is a traditional alcoholic beverage composed of a wide variety of metabolites, which give it many types of tastes and flavors. Previously, we have reported that medium-chain fatty acids contribute to a fatty odor in sake (Takahashi, K., et al., J. Agric. Food Chem., 62, 8478-8485, 2014). In this study, we have reanalyzed the data obtained using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry. The relationship between the chemical components in sake and specific organoleptic properties such as off-flavor and quality has been explored. This led to the identification of the type of chemical compounds present and an assessment of the numerous candidate compounds that correlate with such organoleptic properties in sake. This research provides important fundamental knowledge for the sake-brewing industry.

  1. Ion microscopy with resonant ionization mass spectrometry : time-of-flight depth profiling with improved isotopic precision.

    SciTech Connect

    Pellin, M. J.; Veryovkin, I. V.; Levine, J.; Zinovev, A.; Davis, A. M.; Stephan, T.; Tripa, C. E.; King, B. V.; Savina, M. R.

    2010-01-01

    There are four generally mutually exclusive requirements that plague many mass spectrometric measurements of trace constituents: (1) the small size (limited by the depth probed) of many interesting materials requires high useful yields to simply detect some trace elements, (2) the low concentrations of interesting elements require efficient discrimination from isobaric interferences, (3) it is often necessary to measure the depth distribution of elements with high surface and low bulk contributions, and (4) many applications require precise isotopic analysis. Resonant ionization mass spectrometry has made dramatic progress in addressing these difficulties over the past five years.

  2. IN-SITU PROBING OF RADIATION-INDUCED PROCESSING OF ORGANICS IN ASTROPHYSICAL ICE ANALOGS-NOVEL LASER DESORPTION LASER IONIZATION TIME-OF-FLIGHT MASS SPECTROSCOPIC STUDIES

    SciTech Connect

    Gudipati, Murthy S.; Yang Rui E-mail: ryang73@ustc.edu

    2012-09-01

    Understanding the evolution of organic molecules in ice grains in the interstellar medium (ISM) under cosmic rays, stellar radiation, and local electrons and ions is critical to our understanding of the connection between ISM and solar systems. Our study is aimed at reaching this goal of looking directly into radiation-induced processing in these ice grains. We developed a two-color laser-desorption laser-ionization time-of-flight mass spectroscopic method (2C-MALDI-TOF), similar to matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectroscopy. Results presented here with polycyclic aromatic hydrocarbon (PAH) probe molecules embedded in water-ice at 5 K show for the first time that hydrogenation and oxygenation are the primary chemical reactions that occur in astrophysical ice analogs when subjected to Ly{alpha} radiation. We found that hydrogenation can occur over several unsaturated bonds and the product distribution corresponds to their stabilities. Multiple hydrogenation efficiency is found to be higher at higher temperatures (100 K) compared to 5 K-close to the interstellar ice temperatures. Hydroxylation is shown to have similar efficiencies at 5 K or 100 K, indicating that addition of O atoms or OH radicals to pre-ionized PAHs is a barrierless process. These studies-the first glimpses into interstellar ice chemistry through analog studies-show that once accreted onto ice grains PAHs lose their PAH spectroscopic signatures through radiation chemistry, which could be one of the reason for the lack of PAH detection in interstellar ice grains, particularly the outer regions of cold, dense clouds or the upper molecular layers of protoplanetary disks.

  3. The development of a data system for a combination of liquid chromatography or capillary electrophoresis with an ion trap storage/reflectron time-of-flight mass detector.

    PubMed

    Qian, M G; Wu, J T; Parus, S; Lubman, D M

    1996-01-01

    A data system based upon a 200 MHz transient recorder interface card in a Pentium PC computer is demonstrated for on-line analysis of microbore high-performance liquid chromatography (HPLC), capillary HPLC and capillary electrophoresis (CE) separations using a fast and sensitive ion-trap storage/reflectron time-of-flight mass spectrometric detector (IT-reTOFMS). Under the control of a user-written program, the system is capable of conducting the data acquisition and storage for a minimum of 30 min, at rates exceeding 10 Hz, of individual mass spectra containing 16,000 data points having 10 nsec resolution. The capability is mainly attributed to the use of a data reduction scheme in which only mass intensities higher than a preset threshold are saved as indexed flight-time/intensity pairs. This produces a typical reduction ratio of 30:1 in data set size, yielding faster storage with smaller file size, and permits the complete set of mass spectra to be held in the computer's memory. In addition, the data system is capable of displaying, for real-time evaluation of the analysis, each individual mass spectrum and the total-ion chromatogram. Further, the selected-ion chromatograms of given masses and a 3-dimensional topographic map describing a separation process can be rapidly generated from the collected data for the unambiguous and high fidelity identification of target analytes in a complex mixture.

  4. Discrimination between bacterial spore types using time-of-flight mass spectrometry and matrix-free infrared laser desorption and ionization.

    PubMed

    Ullom, J N; Frank, M; Gard, E E; Horn, J M; Labov, S E; Langry, K; Magnotta, F; Stanion, K A; Hack, C A; Benner, W H

    2001-05-15

    We demonstrate that molecular ions with mass-to-charge ratios (m/z) ranging from a few hundred to 19 050 can be desorbed from whole bacterial spores using infrared laser desorption and no chemical matrix. We have measured the mass of these ions using time-of-flight mass spectrometry and we observe that different ions are desorbed from spores of Bacillus cereus, Bacillus thuringiensis, Bacillus subtilis, and Bacillus niger. Our results raise the possibility of identifying microorganisms using mass spectrometry without conventional sample preparation techniques such as the addition of a matrix. We have measured the dependence of the ion yield from B. subtilis on desorption wavelength over the range 3.05-3.8 microm, and we observe the best results at 3.05 microm. We have also generated mass spectra from whole spores using 337-nm ultraviolet laser desorption, and we find that these spectra are inferior to spectra generated with infrared desorption. Since aerosol analysis is a natural application for matrix-free desorption, we have measured mass spectra from materials such as ragweed pollen and road dust that are likely to form a background to microbial aerosols. We find that these materials are readily differentiated from bacterial spores.

  5. Direct matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of lysozyme contained in hen egg white.

    PubMed

    Smolira, Anna; Hałas, Stanisław

    2016-01-01

    As a natural antibacterial peptide, lysozyme (LZ) is widely used in medicine and the food industry. Despite many years of research on this compound, its new antibacterial properties are still to be determined. The primary aim of this work is to demonstrate the application of the matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometric analysis of LZ directly in hen egg white samples without extraction thereof. The egg white samples were kept over 10 weeks at room temperature and measured every week. The resulting positive and negative ion mass spectra were then compared to determine the intensity of the LZ mass peak. Storage of the egg white for over 10 weeks did not influence the LZ mass peak intensity (both positive and negative). It can be concluded that the LZ concentration in the egg white samples did not vary with time. The effect of the matrix/sample ratio on LZ detection was also examined, and it was found to be different in the case of positive and negative ionization. The mass peaks of LZ oligomeric forms were observed in all mass spectra, so the MALDI method could be used in subsequent studies. PMID:26863071

  6. Enhanced analyte detection using in-source fragmentation of field asymmetric waveform ion mobility spectrometry-selected ions in combination with time-of-flight mass spectrometry.

    PubMed

    Brown, Lauren J; Smith, Robert W; Toutoungi, Danielle E; Reynolds, James C; Bristow, Anthony W T; Ray, Andrew; Sage, Ashley; Wilson, Ian D; Weston, Daniel J; Boyle, Billy; Creaser, Colin S

    2012-05-01

    Miniaturized ultra high field asymmetric waveform ion mobility spectrometry (FAIMS) is used for the selective transmission of differential mobility-selected ions prior to in-source collision-induced dissociation (CID) and time-of-flight mass spectrometry (TOFMS) analysis. The FAIMS-in-source collision induced dissociation-TOFMS (FISCID-MS) method requires only minor modification of the ion source region of the mass spectrometer and is shown to significantly enhance analyte detection in complex mixtures. Improved mass measurement accuracy and simplified product ion mass spectra were observed following FAIMS preselection and subsequent in-source CID of ions derived from pharmaceutical excipients, sufficiently close in m/z (17.7 ppm mass difference) that they could not be resolved by TOFMS alone. The FISCID-MS approach is also demonstrated for the qualitative and quantitative analysis of mixtures of peptides with FAIMS used to filter out unrelated precursor ions thereby simplifying the resulting product ion mass spectra. Liquid chromatography combined with FISCID-MS was applied to the analysis of coeluting model peptides and tryptic peptides derived from human plasma proteins, allowing precursor ion selection and CID to yield product ion data suitable for peptide identification via database searching. The potential of FISCID-MS for the quantitative determination of a model peptide spiked into human plasma in the range of 0.45-9.0 μg/mL is demonstrated, showing good reproducibility (%RSD < 14.6%) and linearity (R(2) > 0.99).

  7. Time-of-flight mass measurements of neutron-rich chromium isotopes up to N =40 and implications for the accreted neutron star crust

    NASA Astrophysics Data System (ADS)

    Meisel, Z.; George, S.; Ahn, S.; Bazin, D.; Brown, B. A.; Browne, J.; Carpino, J. F.; Chung, H.; Cyburt, R. H.; Estradé, A.; Famiano, M.; Gade, A.; Langer, C.; Matoš, M.; Mittig, W.; Montes, F.; Morrissey, D. J.; Pereira, J.; Schatz, H.; Schatz, J.; Scott, M.; Shapira, D.; Sieja, K.; Smith, K.; Stevens, J.; Tan, W.; Tarasov, O.; Towers, S.; Wimmer, K.; Winkelbauer, J. R.; Yurkon, J.; Zegers, R. G. T.

    2016-03-01

    We present the mass excesses of Cr-6459, obtained from recent time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory at Michigan State University. The mass of 64Cr is determined for the first time, with an atomic mass excess of -33.48 (44 ) MeV. We find a significantly different two-neutron separation energy S2 n trend for neutron-rich isotopes of chromium, removing the previously observed enhancement in binding at N =38 . Additionally, we extend the S2 n trend for chromium to N =40 , revealing behavior consistent with the previously identified island of inversion in this region. We compare our results to state-of-the-art shell-model calculations performed with a modified Lenzi-Nowacki-Poves-Sieja interaction in the f p shell, including the g9 /2 and d5 /2 orbits for the neutron valence space. We employ our result for the mass of 64Cr in accreted neutron star crust network calculations and find a reduction in the strength and depth of electron-capture heating from the A =64 isobaric chain, resulting in a cooler than expected accreted neutron star crust. This reduced heating is found to be due to the >1 -MeV reduction in binding for 64Cr with respect to values from commonly used global mass models.

  8. Secondary ion counting for surface-sensitive chemical analysis of organic compounds using time-of-flight secondary ion mass spectroscopy with cluster ion impact ionization

    SciTech Connect

    Hirata, K.; Saitoh, Y.; Chiba, A.; Yamada, K.; Takahashi, Y.; Narumi, K.

    2011-03-15

    We report suitable secondary ion (SI) counting for surface-sensitive chemical analysis of organic compounds using time-of-flight (TOF) SI mass spectroscopy, based on considerably higher emission yields of SIs induced by cluster ion impact ionization. A SI counting system for a TOF SI mass spectrometer was developed using a fast digital storage oscilloscope, which allows us to perform various types of analysis as all the signal pulses constituting TOF SI mass spectra can be recorded digitally in the system. Effects of the SI counting strategy on SI mass spectra were investigated for C{sub 8} and C{sub 60} cluster ion impacts on an organically contaminated silicon wafer and on polytetrafluoroethylene targets by comparing TOF SI mass spectra obtained from the same recorded signals with different SI counting procedures. Our results show that the use of a counting system, which can cope with high SI yields, is necessary for quantitative analysis of SI mass spectra obtained under high SI yield per impact conditions, including the case of cluster ion impacts on organic compounds.

  9. Observation of Accumulated Metal Cation Distribution in Fish by Novel Stigmatic Imaging Time-of-Flight Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Aoki, Jun; Ikeda, Shinichiro; Toyoda, Michisato

    2014-02-01

    The accumulation of radioactive substances in biological organisms is a matter of great concern since the incident at the nuclear power plant in Fukushima, Japan. We have developed a novel technique for observing the distribution of accumulated metal cations in fish that employs a new imaging mass spectrometer, MULTUM-IMG2. Distributions of 133Cs and 88Sr in a sliced section of medaka (Oryzias latipes) are obtained with spatial resolution of µm-scale.

  10. Gas-phase and solution studies of three resorcin[4]arene derivatives using electrospray time-of-flight mass spectrometry.

    PubMed

    Reynolds, James C; Chew, Mei Q; Martin, Helen J; Stubbs, Emma C; Waters, Marguerite A; Crotty, Sarah C; Silvestre-Gonzalez, Vanessa; Chan, Yohan; Thomas, C L Paul; Page, Philip C Bulman; Creaser, Colin S; Heaney, Harry

    2013-01-01

    Electrospray ionisation mass spectrometry (ESI-MS) has been used to study the relative gas-phase proton and alkali metal (Li, Na, K and Cs) binding affinities of three different resorcin[4]arenes using the kinetic method. Collision-induced dissociation (CID) was used to study the fragmentation of resorcin[4]arene heterodimer sandwich complexes, allowing the relative binding affinity order to be established. All the alkali metal cations have the same gas-phase binding affinity order with the resorcin[4]arene host molecules. At collision energies of > or = 13eV, one of the [resorcin[4]arene+Metal]+, (Metal = Li, Na, K) ions fragmented through break-up of the resorcin[4]arene, whilst the other host resorcin[4]arene remained intact, causing an apparent change in binding affinity at high collision energy. This effect was not observed with caesium, since all complex ions dissociated readily under CID by displacement of the caesium cation. The binding affinity for the protonated resorcin[4]arenes was found to be different from the alkali metal cation binding affinity because of the higher proton affinity of the nitrogen-containing resorcin[4]arenes. It is shown that resorcin[4]arenes containing an oxazine ring can be converted into a ring-opened derivative via an Eschweiler-CLarke reaction in the presence of formic acid. A second ring-opening process also occurs, including a hydrolysis reaction that results in apparent Losses of 12 mass units from the intact resorcin[4]arene. Both these reactions occur in solution before mass spectrometric investigation and cannot be achieved by CID. This observation was confirmed by inducing the Eschweiter-CLarke reaction in a model benzoxazine compound.

  11. A miniaturised electron ionisation time-of-flight mass spectrometer that uses a unique helium ion removal pulsing technique specifically for gas analysis.

    PubMed

    Qing, Jiang; Huang, Zhengxu; Zhang, Yan; Zhu, Hui; Tan, Guobin; Gao, Wei; Yang, Peng-yuan

    2013-06-21

    A miniaturised reflectron time-of-flight mass spectrometer combined with an electron ionisation ion source has been developed for the analysis of gases. An entirely new helium ion removal pulsing technique in this mass spectrometer is used to achieve an improved performance for the first time. The helium carrier gas, which enters into the source along with the gaseous sample, is simultaneously ionised and then orthogonally introduced into the time-of-fight mass analyser. Once the relatively light helium ions in the ion packet become extremely close to the reflectron plate (B-plate for short in this article), a modulated pulse is instantaneously applied on the B-plate and a negative reflectron voltage is set to the B-plate and lasts for a very short period, during which all the helium ions are directly bumped into the B-plate and subsequently removed. The helium ion removal pulsing technique can efficiently avoid saturation of the micro-channel plate caused by too many helium ions. A compact and durable instrument is designed, which has a mass resolving resolution greater than 400 FWHM for online gas analysis. The technology may also be further developed to remove other ions for TOF mass spectrometry.

  12. Ion trace detection algorithm to extract pure ion chromatograms to improve untargeted peak detection quality for liquid chromatography/time-of-flight mass spectrometry-based metabolomics data.

    PubMed

    Wang, San-Yuan; Kuo, Ching-Hua; Tseng, Yufeng J

    2015-03-01

    Able to detect known and unknown metabolites, untargeted metabolomics has shown great potential in identifying novel biomarkers. However, elucidating all possible liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) ion signals in a complex biological sample remains challenging since many ions are not the products of metabolites. Methods of reducing ions not related to metabolites or simply directly detecting metabolite related (pure) ions are important. In this work, we describe PITracer, a novel algorithm that accurately detects the pure ions of a LC/TOF-MS profile to extract pure ion chromatograms and detect chromatographic peaks. PITracer estimates the relative mass difference tolerance of ions and calibrates the mass over charge (m/z) values for peak detection algorithms with an additional option to further mass correction with respect to a user-specified metabolite. PITracer was evaluated using two data sets containing 373 human metabolite standards, including 5 saturated standards considered to be split peaks resultant from huge m/z fluctuation, and 12 urine samples spiked with 50 forensic drugs of varying concentrations. Analysis of these data sets show that PITracer correctly outperformed existing state-of-art algorithm and extracted the pure ion chromatograms of the 5 saturated standards without generating split peaks and detected the forensic drugs with high recall, precision, and F-score and small mass error.

  13. Effects of Growth Medium on Matrix-Assisted Laser Desorption–Ionization Time of Flight Mass Spectra: a Case Study of Acetic Acid Bacteria

    PubMed Central

    Wieme, Anneleen D.; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita

    2014-01-01

    The effect of the growth medium used on the matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectra generated and its consequences for species and strain level differentiation of acetic acid bacteria (AAB) were determined by using a set of 25 strains. The strains were grown on five different culture media that yielded a total of more than 600 mass spectra, including technical and biological replicates. The results demonstrate that the culture medium can have a profound effect on the mass spectra of AAB as observed in the presence and varying signal intensities of peak classes, in particular when culture media do not sustain optimal growth. The observed growth medium effects do not disturb species level differentiation but strongly affect the potential for strain level differentiation. The data prove that a well-constructed and robust MALDI-TOF mass spectrometry identification database should comprise mass spectra of multiple reference strains per species grown on different culture media to facilitate species and strain level differentiation. PMID:24362425

  14. Flow-modulated comprehensive two-dimensional gas chromatography combined with a high-resolution time-of-flight mass spectrometer: a proof-of-principle study.

    PubMed

    Tranchida, Peter Q; Salivo, Simona; Franchina, Flavio A; Mondello, Luigi

    2015-03-01

    The present research is focused on the evaluation of a recently developed high-resolution time-of-flight mass spectrometer (HR TOF MS), under the challenging conditions of a flow-modulation comprehensive two-dimensional gas chromatography (FM GC × GC) experiment. The HR TOF MS instrument was operated at a spectral generation frequency of 30 Hz and a mass resolution of ≥25,000 (fwhm). The effluent exiting the second-dimension column was in the range 6-8 mL/min, with part directed to waste to avoid exceeding the maximum pumping capacity of the MS system. An FM GC × GC-HR TOF MS method was developed for the untargeted and targeted analysis of a sample of high complexity, namely, heavy gas oil. With regard to the untargeted results, these were satisfactory in relation to MS database searching and mass accuracies. Considering the targeted data, the high selectivity of the MS system was highlighted by the use of accurate mass extracted-ion-chromatograms with narrow mass windows (±5 and ±1 ppm), for specific classes of polyaromatic sulfur heterocycles (PASHs), namely, benzothiophenes and dibenzothiophenes. Finally, the instrumental performance was also evaluated through the injection of standard solutions of four classes of PASHs.

  15. Screening of environmental contaminants in honey bee wax comb using gas chromatography-high-resolution time-of-flight mass spectrometry.

    PubMed

    Gómez-Ramos, M M; García-Valcárcel, A I; Tadeo, J L; Fernández-Alba, A R; Hernando, M D

    2016-03-01

    This study reports an analytical approach intended to be used for investigation of non-targeted environmental contaminants and to characterize the organic pollution pattern of bee wax comb samples. The method comprises a generic extraction followed by detection with gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF-MS), operated in electron impact ionization (EI) mode. The screening approach for the investigation of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS(1) with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, the molecular formula of representative ions (molecular ion when present in the EI spectrum) and, for at least other two fragment ions, was provided for those with an accurate mass scoring (mass error < 5 ppm). This methodology was applied for screening environmental contaminants in 50 samples of bee wax comb. This approach has allowed the tentative identification of some GC-amenable contaminants belonging to different chemical groups, among them, phthalates and polycyclic aromatic hydrocarbons (PAHs), along with residues of veterinary treatments used in apiculture.

  16. Flow-modulated comprehensive two-dimensional gas chromatography combined with a high-resolution time-of-flight mass spectrometer: a proof-of-principle study.

    PubMed

    Tranchida, Peter Q; Salivo, Simona; Franchina, Flavio A; Mondello, Luigi

    2015-03-01

    The present research is focused on the evaluation of a recently developed high-resolution time-of-flight mass spectrometer (HR TOF MS), under the challenging conditions of a flow-modulation comprehensive two-dimensional gas chromatography (FM GC × GC) experiment. The HR TOF MS instrument was operated at a spectral generation frequency of 30 Hz and a mass resolution of ≥25,000 (fwhm). The effluent exiting the second-dimension column was in the range 6-8 mL/min, with part directed to waste to avoid exceeding the maximum pumping capacity of the MS system. An FM GC × GC-HR TOF MS method was developed for the untargeted and targeted analysis of a sample of high complexity, namely, heavy gas oil. With regard to the untargeted results, these were satisfactory in relation to MS database searching and mass accuracies. Considering the targeted data, the high selectivity of the MS system was highlighted by the use of accurate mass extracted-ion-chromatograms with narrow mass windows (±5 and ±1 ppm), for specific classes of polyaromatic sulfur heterocycles (PASHs), namely, benzothiophenes and dibenzothiophenes. Finally, the instrumental performance was also evaluated through the injection of standard solutions of four classes of PASHs. PMID:25642594

  17. Screening of environmental contaminants in honey bee wax comb using gas chromatography-high-resolution time-of-flight mass spectrometry.

    PubMed

    Gómez-Ramos, M M; García-Valcárcel, A I; Tadeo, J L; Fernández-Alba, A R; Hernando, M D

    2016-03-01

    This study reports an analytical approach intended to be used for investigation of non-targeted environmental contaminants and to characterize the organic pollution pattern of bee wax comb samples. The method comprises a generic extraction followed by detection with gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF-MS), operated in electron impact ionization (EI) mode. The screening approach for the investigation of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS(1) with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, the molecular formula of representative ions (molecular ion when present in the EI spectrum) and, for at least other two fragment ions, was provided for those with an accurate mass scoring (mass error < 5 ppm). This methodology was applied for screening environmental contaminants in 50 samples of bee wax comb. This approach has allowed the tentative identification of some GC-amenable contaminants belonging to different chemical groups, among them, phthalates and polycyclic aromatic hydrocarbons (PAHs), along with residues of veterinary treatments used in apiculture. PMID:26527334

  18. Analysis of estrogens in sediment from a sewage-impacted urban estuary using high-performance liquid chromatography/time-of-flight mass spectrometry.

    PubMed

    Reddy, Sharanya; Brownawell, Bruce J

    2005-05-01

    We describe a highly selective and sensitive method for determination of estrone (E1) and beta-estradiol (E2) in sediments, using high-performance liquid chromatography/time-of-flight (HPLC-ToF) mass spectrometry. The method involved sequential cleanup of sediment extracts over solid phase extraction cartridges, normal phase HPLC, and immunoaffinity extraction, which combine to remove coeluting matrix interferences. Resulting method detection limits (0.03 and 0.04 ng/g for E1 and E2, respectively) are sufficient to determine E1 and E2 in estuarine sediments collected from sewage-impacted Jamaica Bay (New York, NY, USA). The ToF analyzer has a higher resolution (>6,000) than quadrupole mass analyzers and can provide accurate mass estimation to within 2 mDa, which helped in distinguishing steroids from isobaric matrix interferences. The E1 and E2 were internally mass calibrated with respect to their coeluting surrogate standards, and the mass measurement error was between 1.1 and 1.4 mDa. The levels of E1 and E2 ranged between 0.07 to 2.52 and 0.05 to 0.53 ng/g, respectively. The measured concentrations of steroids in sediments correlated closely with other wastewater tracers. Despite the low concentrations of sediment-associated estrogens, their predicted estrogenic potency exceeds that of other measured estrogenic contaminants. PMID:16110980

  19. Investigation of polymer thin films by use of Bi-cluster-ion-supported time of flight secondary ion mass spectrometry.

    PubMed

    Straif, Christoph J; Hutter, Herbert

    2009-04-01

    The investigation and analysis of polymer thin films with Bi(n)(+), n = 1-7 cluster ions has been demonstrated by means of static secondary ion mass spectrometry (SIMS). The highly specific signal enhancement of these primary ions combined with the individual fragmentation pattern of poly(4-vinylphenol) and poly(methyl methacrylate) is the basic principle for a modified approach of data reduction derived from the well-established g-SIMS procedure. Based on mass spectra, which correspond to different cluster ion sizes, not only a clear distinction between the two polymers is feasible but also a further simplification of the data can be demonstrated. It has been successfully proven that characteristic polymer-relevant species can be refined out of the large amount of unspecific and highly fragmented secondary ions, which are usually present in SIMS spectra. Therefore, a more precise and direct interpretation of complex organic fragments becomes feasible, which consequently enables the investigation of even more sophisticated samples.

  20. Analysis of Microbial Mixtures by Matrix-assisted Laser Desorption/Ionization time-of-flight Mass Spectrometry

    SciTech Connect

    Wahl, Karen L.; Wunschel, Sharon C.; Jarman, Kristin H.; Valentine, Nancy B.; Petersen, Catherine E.; Kingsley, Mark T.; Zartolas, Kimberly A.; Saenz, Adam J.

    2002-12-15

    Many different laboratories are currently developing mass-spectrometric techniques to analyze and identify microorganisms. However, minimal work has been done with mixtures of bacteria. To demonstrate that microbial mixtures could be analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), mixed bacterial cultures were analyzed in a double-blind fashion. Nine different bacterial species currently in our MALDI-MS fingerprint library were used to generate 50 different simulated mixed bacterial cultures similar to that done for an initial blind study previously reported.(1) The samples were analyzed by MALDI-MS with automated data extraction and analysis algorithms developed in our laboratory. The components present in the sample were identified correctly to the species level in all but one of the samples. However, correctly eliminating closely related organisms was challenging for the current algorithms, especially in differentiating Serratia marcescens, Escherichia coli, and Yersinia enterocolitica, which have some similarities in their MALDI-MS fingerprints. Efforts to improve the specificity of the algorithms are in progress.

  1. Tropical Greenhouse Measurements of Volatile Organic Compounds Using Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectromety (PTR-TOF-MS)

    NASA Astrophysics Data System (ADS)

    Veres, P.; Auld, J.; Williams, J.

    2012-04-01

    In this presentation, we will summarize the results of measurements made in an approximately 1300 m3 tropical greenhouse at the Johannes Gutenberg University botanical garden in Mainz Germany conducted over a one month period. The greenhouse is home to a large variety of plant species from hot and humid regions of the world. The greenhouse is also host to several crops such as Cocoa and Cola Nut as well as ornamental plants. A particular focus of the species maintained are those which are considered ant plants, or plants which have an intimate relationship with ants in tropical habitats. Volatile organic compounds (VOCs) were measured using a Switchable Reagent Ion Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-TOF-MS) using H3O+, NO+, and O2+ ion chemistry. Measurements will be presented both for primary emissions observed in the closed greenhouse atmosphere as well as the oxidation products observed after the introduction of ambient ozone. The high resolving power (5000 m/Δm) of the time-of-flight instrument allows for the separation of isobaric species. In particular, both isoprene (68.1170 amu) and furan (68.0740 amu) were observed and separated as primary emissions during this study. The significance of this will be discussed in terms of both atmospheric implications as well as with respect to previous measurements of isoprene obtained using quadrupole PTR-MS where isobaric separation of these compounds is not possible. Additionally observed species (e.g. Methanol, Acetaldehyde, MVK and MEK) will be discussed in detail with respect to their behavior as a function of light, temperature and relative humidity. The overall instrument performance of the PTR-TOF-MS technique using the H3O+, NO+, and O2+ primary ions for the measurement of VOCs will be evaluated.

  2. Determination of trace rare earth elements in gadolinium aluminate by inductively coupled plasma time of flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Saha, Abhijit; Deb, S. B.; Nagar, B. K.; Saxena, M. K.

    An analytical methodology was developed for the precise quantification of ten trace rare earth elements (REEs), namely, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm, in gadolinium aluminate (GdAlO3) employing an ultrasonic nebulizer (USN)-desolvating device based inductively coupled plasma mass spectrometry (ICP-MS). A microwave digestion procedure was optimized for digesting 100 mg of the refractory oxide using a mixture of sulphuric acid (H2SO4), phosphoric acid (H3PO4) and water (H2O) with 1400 W power, 10 min ramp and 60 min hold time. An USN-desolvating sample introduction system was employed to enhance analyte sensitivities by minimizing their oxide ion formation in the plasma. Studies on the effect of various matrix concentrations on the analyte intensities revealed that precise quantification of the analytes was possible with matrix level of 250 mg L- 1. The possibility of using indium as an internal standard was explored and applied to correct for matrix effect and variation in analyte sensitivity under plasma operating conditions. Individual oxide ion formation yields were determined in matrix matched solution and employed for correcting polyatomic interferences of light REE (LREE) oxide ions on the intensities of middle and heavy rare earth elements (MREEs and HREEs). Recoveries of ≥ 90% were achieved for the analytes employing standard addition technique. Three real samples were analyzed for traces of REEs by the proposed method and cross validated for Eu and Nd by isotope dilution mass spectrometry (IDMS). The results show no significant difference in the values at 95% confidence level. The expanded uncertainty (coverage factor 1σ) in the determination of trace REEs in the samples were found to be between 3 and 8%. The instrument detection limits (IDLs) and the method detection limits (MDLs) for the ten REEs lie in the ranges 1-5 ng L- 1 and 7-64 μg kg- 1 respectively.

  3. Monoterpene separation by coupling proton transfer reaction time-of-flight mass spectrometry with fastGC.

    PubMed

    Materić, Dušan; Lanza, Matteo; Sulzer, Philipp; Herbig, Jens; Bruhn, Dan; Turner, Claire; Mason, Nigel; Gauci, Vincent

    2015-10-01

    Proton transfer reaction mass spectrometry (PTR-MS) is a well-established technique for real-time analysis of volatile organic compounds (VOCs). Although it is extremely sensitive (with sensitivities of up to 4500 cps/ppbv, limits of detection <1 pptv and the response times of approximately 100 ms), the selectivity of PTR-MS is still somewhat limited, as isomers cannot be separated. Recently, selectivity-enhancing measures, such as manipulation of drift tube parameters (reduced electric field strength) and using primary ions other than H3O(+), such as NO(+) and O2 (+), have been introduced. However, monoterpenes, which belong to the most important plant VOCs, still cannot be distinguished so more traditional technologies, such as gas chromatography mass spectrometry (GC-MS), have to be utilised. GC-MS is very time consuming (up to 1 h) and cannot be used for real-time analysis. Here, we introduce a sensitive, near-to-real-time method for plant monoterpene research-PTR-MS coupled with fastGC. We successfully separated and identified six of the most abundant monoterpenes in plant studies (α- and β-pinenes, limonene, 3-carene, camphene and myrcene) in less than 80 s, using both standards and conifer branch enclosures (Norway spruce, Scots pine and black pine). Five monoterpenes usually present in Norway spruce samples with a high abundance were separated even when the compound concentrations were diluted to 20 ppbv. Thus, fastGC-PTR-ToF-MS was shown to be an adequate one-instrument solution for plant monoterpene research. PMID:26253230

  4. Rapid detection of porins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

    PubMed

    Hu, Yan-Yan; Cai, Jia-Chang; Zhou, Hong-Wei; Zhang, Rong; Chen, Gong-Xiang

    2015-01-01

    The rapid and cost-efficient determination of carbapenem resistance is an important prerequisite for the choice of an adequate antibiotic therapy. A MALDI-TOF MS-based assay was set up to detect porins in the current study. A loss of the components of porin alone such as OmpK35/OmpK36 or together with the production of carbapenemases will augment the carbapenem resistance. Ten strains of Escherichia coli and eight strains of Klebsiella pneumoniae were conducted for both sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and MALDI-TOF MS analysis. MALDI-TOF/TOF MS analysis was then performed to verify the correspondence of proteins between SDS-PAGE and MALDI-TOF MS. The results indicated that the mass spectrum of ca. 35,000, 37,000, and 38,000-m/z peaks of E. coli ATCC 25922 corresponded to OmpA, OmpC, and OmpF with molecular weight of approximately ca. 38, 40, and 41 kDa in SDS-PAGE gel, respectively. The band of OmpC and OmpF porins were unable to be distinguished by SDS-PAGE, whereas it was easy to be differentiated by MALDI-TOF MS. As for K. pneumoniae isolates, the mass spectrum of ca. 36,000 and 38,600-m/z peaks was observed corresponding to OmpA and OmpK36 with molecular weight of approximately ca. 40 and 42 kDa in SDS-PAGE gel, respectively. Porin OmpK35 was not observed in the current SDS-PAGE, while a 37,000-m/z peak was found in K. pneumoniae ATCC 13883 and carbapenem-susceptible strains by MALDI-TOF MS which was presumed to be the characteristic peak of the OmpK35 porin. Compared with SDS-PAGE, MALDI-TOF MS is able to rapidly identify the porin-deficient strains within half an hour with better sensitivity, less cost, and is easier to operate and has less interference.

  5. Quantification of genetically modified soya using strong anion exchange chromatography and time-of-flight mass spectrometry.

    PubMed

    Chang, Po-Chih; Reddy, P Muralidhar; Ho, Yen-Peng

    2014-09-01

    Stable-isotope dimethyl labeling was applied to the quantification of genetically modified (GM) soya. The herbicide-resistant gene-related protein 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) was labeled using a dimethyl labeling reagent, formaldehyde-H2 or -D2. The identification and quantification of CP4 EPSPS was performed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The CP4 EPSPS protein was separated from high abundance proteins using strong anion exchange chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Then, the tryptic peptides from the samples and reference were labeled with formaldehyde-H2 and formaldehyde-D2, respectively. The two labeled pools were mixed and analyzed using MALDI-MS. The data showed a good correlation between the peak ratio of the H- and D-labeled peptides and the GM soya percentages at 0.5, 1, 3, and 5 %, with R (2) of 0.99. The labeling reagents are readily available. The labeling experiments and the detection procedures are simple. The approach is useful for the quantification of GM soya at a level as low as 0.5 %.

  6. Development of a linear ion trap/orthogonal-time-of-flight mass spectrometer for time-dependent observation of product ions by ultraviolet photodissociation of peptide ions.

    PubMed

    Kim, Tae-Young; Schwartz, Jae C; Reilly, James P

    2009-11-01

    A hybrid linear ion trap/orthogonal time-of-flight (TOF) mass spectrometer has been developed to observe time-dependent vacuum ultraviolet photodissociation product ions. In this apparatus, a reflectron TOF mass analyzer is orthogonally interfaced to an LTQ using rf-only octopole and dc quadrupole ion guides. Precursor ions are generated by electrospray ionization and isolated in the ion trap. Subsequently they are directed to the TOF source where photodissociation occurs and product ions are extracted for mass analysis. To detect photodissociation product ions having axially divergent trajectories, a large rectangular detector is utilized. With variation of the time between photodissociation and orthogonal extraction in the TOF source, product ions formed over a range of times after photoexcitation can be sampled. Time-dependent observation of product ions following 157 nm photodissociation of a singly charged tryptic peptide ion (NWDAGFGR) showed that prompt photofragment ions (x- and v-type ions) dominate the tandem mass spectrum up to 1 micros after the laser shot, but the intensities of low energy thermal fragment ions (y-type ions) become comparable several microseconds later. Different proton mobilization time scales were observed for arginine- and lysine-terminated tryptic peptides.

  7. Assessment of gas chromatography time-of-flight accurate mass spectrometry for identification of volatile and semi-volatile compounds in honey.

    PubMed

    Moniruzzaman, M; Rodríguez, I; Ramil, M; Cela, R; Sulaiman, S A; Gan, S H

    2014-11-01

    The performance of gas chromatography (GC) combined with a hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) system for the determination of volatile and semi-volatile compounds in honey samples is evaluated. After headspace (HS) solid-phase microextraction (SPME) of samples, the accurate mass capabilities of the above system were evaluated for compounds identification. Accurate scan electron impact (EI) MS spectra allowed discriminating compounds displaying the same nominal masses, but having different empirical formulae. Moreover, the use of a mass window with a width of 0.005 Da provided highly specific chromatograms for selected ions, avoiding the contribution of interferences to their peak areas. Additional information derived from positive chemical ionization (PCI) MS spectra and ion product scan MS/MS spectra permitted confirming the identity of novel compounds. The above possibilities are illustrated with examples of honey aroma compounds, belonging to different chemical classes and containing different elements in their molecules. Examples of compounds whose structures could not be described are also provided. Overall, 84 compounds, from a total of 89 species, could be identified in 19 honey samples from 3 different geographic areas in the world. The suitability of responses measured for selected ions, corresponding to above species, for authentication purposes is assessed through principal components analysis. PMID:25127626

  8. [Coupling of gas chromatography with single photon ionization time-of-flight mass spectrometry and its application to characterization of compounds in diesel].

    PubMed

    Xie, Yuanyuan; Hua, Lei; Chen, Ping; Hou, Keyong; Jiang, Jichun; Wang, Yan; Li, Haiyang

    2015-02-01

    A novel analytical method coupling gas chromatography (GC) with single photon ionization time-of-flight mass spectrometry (SPI-TOF MS) has been developed. First of all, a double-wall-tube transfer line was built to combine GC with SPI-TOF MS, which realized seamless connection between GC and SPI ion source. Based on this, standard n-pentadecane and benzene/toluene/xylene standard gas mixtures were used to study important voltage parameters of the ion source. After the optimization of the ion source voltages, pure molecular ion peaks of the analytes were obtained in the mass spectra and qualitative analysis of different kinds of organic compounds were eventually realized rapidly and accurately. At last, GC/SPI-TOF MS was applied to the characterization of volatile and semvolatile organic compounds in diesel and two-dimensional spectra of GC×SPI-TOF MS were obtained. Without complicated spectra interpretation and data processing, volatile and semi-volatile organic compounds in diesel have been classified qualitatively by ion mass-to-charge ratio (m/z) in SPI mass spectra, including aliphatic compounds, aromatic compounds and nitrogen-containing compounds with low concentration such as benzopyrroles. Isomeric compounds in diesel were separated and identified by retention times of chromatographic peaks. The results indicate that the proposed analytical method of GC/SPI-TOF MS is suitable for the characterization of complicated samples such as diesel and environmental pollutants with easy operation and high efficiency.

  9. [Application of gas chromatography-high resolution quadrupole time of flight mass spectrometry to the analysis of benzaldehyde, benzyl alcohol acetophenone and phenylacetaldehyde in complex aromatic samples].

    PubMed

    Liu, Junyan; Cao, Zhe; Li, Jiwen; Wang, Zheming; Wang, Chuan; Gu, Songyuan

    2015-02-01

    The study focuses on the quantitative analytical characterization of benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde in complex aromatic samples by gas chromatography-high resolution quadrupole time of flight mass spectrometry (GC-QTOF MS). The four compounds in real sample were accurately qualified and quantified through a comprehensive analysis of the GC retention times and the accurate masses of the ion fragments obtained by the high resolution MS. The new method therefore effectively avoids the interference of the real sample substrate, which reduces the accuracy of the analysis results. The peak area of the characteristic ion fragment for each compound was used for quantitation calculation. The MS signal responses of the four compounds showed good linear relationships with the corresponding mass concentrations and the linear regression coefficients were greater than 0. 99. The method recoveries were 87. 97% - 103.01%. The limits of detection (LODs) were 0. 01, 0. 03, 0. 02 and 0. 01 mg/L for benzaldehyde, benzyl alcohol, acetophenone and phenylacetaldehyde respectively. The contents of the four compounds in three real samples were analyzed. The study provided a new strategy for oxygenate analysis in complex aromatic samples using GC-QTOF MS. By measuring the accurate masses, the new method reduces the reliance on chromatographic separation ability and makes up the shortcomings of the traditional GC-MS methods.

  10. Trace analysis of total naphthenic acids in aqueous environmental matrices by liquid chromatography/mass spectrometry-quadrupole time of flight mass spectrometry direct injection.

    PubMed

    Brunswick, Pamela; Shang, Dayue; van Aggelen, Graham; Hindle, Ralph; Hewitt, L Mark; Frank, Richard A; Haberl, Maxine; Kim, Marcus

    2015-07-31

    A rapid and sensitive liquid chromatography quadrupole time of flight method has been established for the determination of total naphthenic acid concentrations in aqueous samples. This is the first methodology that has been adopted for routine, high resolution, high throughput analysis of total naphthenic acids at trace levels in unprocessed samples. A calibration range from 0.02 to 1.0μgmL(-1) total Merichem naphthenic acids was validated and demonstrated excellent accuracy (97-111% recovery) and precision (1.9% RSD at 0.02μgmL(-1)). Quantitative validation was also demonstrated in a non-commercial oil sands process water (OSPW) acid extractable organics (AEOs) fraction containing a higher percentage of polycarboxylic acid isomers than the Merichem technical mix. The chromatographic method showed good calibration linearity of ≥0.999 RSQ to 0.005μgmL(-1) total naphthenic acids with a precision <3.1% RSD and a calculated detection limit of 0.0004μgmL(-1) employing Merichem technical mix reference material. The method is well suited to monitoring naturally occurring and industrially derived naphthenic acids (and other AEOs) present in surface and ground waters in the vicinity of mining developments. The advantage of the current method is its direct application to unprocessed environmental samples and to examine natural naphthenic acid isomer profiles. It is noted that where the isomer profile of samples differs from that of the reference material, results should be considered semi-quantitative due to the lack of matching isomer content. The fingerprint profile of naphthenic acids is known to be transitory during aging and the present method has the ability to adapt to monitoring of these changes in naphthenic acid content. The method's total ion scan approach allows for data previously collected to be examined retrospectively for specific analyte mass ions of interest. A list of potential naphthenic acid isomers that decrease in response with aging is proposed

  11. Evaluation of a High Resolving Power Time-of-Flight Mass Spectrometer for Drug Analysis in Terms of Resolving Power and Acquisition Rate

    NASA Astrophysics Data System (ADS)

    Pelander, Anna; Decker, Petra; Baessmann, Carsten; Ojanperä, Ilkka

    2011-02-01

    Liquid chromatography time-of-flight mass spectrometry (LC-TOFMS) is applied increasingly to various fields of small molecule analysis. The moderate resolving power (RP) of standard TOFMS instruments poses a risk of false negative results when complex biological matrices are to be analyzed. In this study, the performance of a high resolving power TOFMS instrument (maXis by Bruker Daltonik, Bremen, Germany) was evaluated for drug analysis. By flow injection analysis of critical drug mixtures, including a total of 17 compounds with nominal masses of 212-415 Da and with mass differences of 8.8-23.5 mDa, RP varied from 34,400 to 51,900 (FWHM). The effect of acquisition rate on RP, mass accuracy, and isotopic pattern fit was studied by applying 1, 2, 5, 10, and 20 Hz acquisition rates in a 16 min gradient elution LC separation. All three variables were independent of the acquisition rate, with an average mass accuracy and isotopic pattern fit factor (mSigma) of 0.33 ppm and 5.9, respectively. The average relative standard deviation of RP was 1.8%, showing high repeatability. The performance was tested further with authentic urine extracts containing a co-eluting compound pair with a nominal mass of 296 Da and an 11.2 mDa mass difference. The authentic sample components were readily resolved and correctly identified by the automated data analysis. The average RP, mass accuracy, and isotopic pattern fit were 36,600, 0.9 ppm, and 7.3 mSigma, respectively.

  12. New way to quantify multiple steroidal compounds in wastewater by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

    PubMed

    Kopperi, Matias; Ruiz-Jiménez, José; Hukkinen, Janne I; Riekkola, Marja-Liisa

    2013-01-25

    The applicability of comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry to the screening of steroidal compounds in wastewater is demonstrated. Advanced software was utilized to identify unknown compounds in complex two-dimensional chromatograms exploiting retention indices and two different mass spectral databases. Response factors calculated as a function of the individual mass spectra of six commercial standards at different concentrations were used to develop a model allowing the quantitation of all steroidal compounds identified in the sample. The model, based on partial least squares regression equations, provided good accuracy (prediction error < 16%) in the quantitation of steroidal compounds, so offering a valuable alternative to conventional quantitation methods where reference compounds are required for the verification of analytical measurements. Special attention was paid to the development of an exhaustive sample preparation method for the separate analysis of conjugated and free steroids in both water phase and suspended solid particles. The method, including the exploitation of chemometrics, was successfully applied to the determination of steroidal compounds in effluent and influent waters collected at a local wastewater treatment plant. PMID:23312334

  13. Dispersive liquid-liquid microextraction for the determination of three cytokinin compounds in fruits and vegetables by liquid chromatography with time-of-flight mass spectrometry.

    PubMed

    Campillo, N; Viñas, P; Férez-Melgarejo, G; Hernández-Córdoba, M

    2013-11-15

    The paper presents a novel approach for the determination of three cytokinin compounds, thidiazuron (TDZ), 1,3-diphenylurea (1,3-DPU) and forchlorfenuron (CPPU), in fruit and vegetables samples using liquid chromatography with electrospray ionization and time-of-flight mass spectrometry (LC-ESI-TOFMS). Analytes were extracted from the sample matrix with ethanol, and the extract, after dilution with water, was submitted to dispersive liquid-liquid microextraction (DLLME). Once acetonitrile and 1,2-dichloroethane had been selected as extraction and disperser solvents, respectively, the influence of the following experimental parameters was studied using a Plackett-Burman design: volume of extraction and disperser solvents, sample mass and time and speed of centrifugation. The best analytical conditions were 250 µL 1,2-dichloroethane, 1.5 mL acetonitrile, 5 g sample mass, and centrifugation at 3000 rpm for 3 min. The optimized method provided DLs in the range 0.02-0.05 ng g(-1), depending on the compound. Satisfactory recovery values between 89 and 106% were obtained for spiked samples (kiwifruit, watermelon, grape and tomato) in the 0.2-1.0 ng g(-1) concentration range, depending on the compound. None of the target analytes was detected in any of the samples analyzed.

  14. Laser ablation with resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for determining aromatic lignin volatilization products from biomass

    NASA Astrophysics Data System (ADS)

    Mukarakate, Calvin; Scheer, Adam M.; Robichaud, David J.; Jarvis, Mark W.; David, Donald E.; Ellison, G. Barney; Nimlos, Mark R.; Davis, Mark F.

    2011-03-01

    We have designed and developed a laser ablation/pulsed sample introduction/mass spectrometry platform that integrates pyrolysis (py) and/or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of He, then skimmed and introduced into an ionization region. One color resonance-enhanced multiphoton ionization (1+1 REMPI) is used, resulting in highly selective detection of lignin subunits from complex vapors of biomass materials. The spectra obtained by py-REMPI-TOFMS and LA-REMPI-TOFMS display high selectivity and decreased fragmentation compared to spectra recorded by an electron impact ionization molecular beam mass spectrometer (EI-MBMS). The laser ablation method demonstrates the ability to selectively isolate and volatilize specific tissues within the same plant material and then detect lignin-based products from the vapors with enhanced sensitivity. The identification of select products observed in the LA-REMPI-TOFMS experiment is confirmed by comparing their REMPI wavelength scans with that of known standards.

  15. Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS).

    PubMed

    Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

    2015-01-01

    Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures.

  16. Determination of the disulfide bond arrangement of human respiratory syncytial virus attachment (G) protein by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    PubMed Central

    Gorman, J. J.; Ferguson, B. L.; Speelman, D.; Mills, J.

    1997-01-01

    The attachment protein or G protein of the A2 strain of human respiratory syncytial virus (RSV) was digested with trypsin and the resultant peptides separated by reverse-phase high-performance liquid chromatography (HPLC). One tryptic peptide produced a mass by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) corresponding to residues 152-187 with the four Cys residues of the ectodomain (residues 173, 176, 182, and 186) in disulfide linkage and absence of glycosylation. Sub-digestion of this tryptic peptide with pepsin and thermolysin produced peptides consistent with disulfide bonds between Cys173 and Cys186 and between Cys176 and Cys182. Analysis of ions produced by post-source decay of a peptic peptide during MALDI-TOF-MS revealed fragmentation of peptide bonds with minimal fission of an inter-chain disulfide bond. Ions produced by this unprecedented MALDI-induced post-source fragmentation corroborated the existence of the disulfide arrangement deduced from mass analysis of proteolysis products. These findings indicate that the ectodomain of the G protein has a non-glycosylated subdomain containing a "cystine noose." PMID:9194191

  17. Comprehensive multidimensional separation methods by hyphenation of single-photon ionization time-of-flight mass spectrometry (SPI-TOF-MS) with GC and GCxGC.

    PubMed

    Eschner, Markus S; Welthagen, Werner; Gröger, Thomas M; Gonin, Marc; Fuhrer, Katrin; Zimmermann, Ralf

    2010-10-01

    One- and comprehensive two-dimensional gas chromatography were hyphenated with soft photoionization mass spectrometry. The characteristics of these two- and three-dimensional comprehensive separation techniques are discussed in detail. Using the innovative electron beam pumped excimer light source (EBEL) for single-photon ionization (SPI), organic molecules with ionization energies (E ( i )) of below 9.8 eV can be detected by a time-of-flight mass spectrometer (TOF-MS). SPI with 126 nm vacuum ultraviolet (VUV) photons enables the universal and soft ionization of organic molecules. SPI-TOF-MS hyphenated to one-dimensional gas chromatography results in a comprehensive two-dimensional separation method (GCxMS). To demonstrate this, diesel fuel was analyzed, and the resulting GCxMS chromatograms are discussed in depth. A three-dimensional separation method was also realized by combining comprehensive two-dimensional gas chromatography (GCxGC) with SPI-MS. In the resulting separation space, constituents originating from mineral oil diesel blended with biodiesel were dispersed along the two GC separation axes, while the molecular mass axis served as a third separation dimension.

  18. Real-time trace detection and identification of chemical warfare agent simulants using recent advances in proton transfer reaction time-of-flight mass spectrometry.

    PubMed

    Petersson, Fredrik; Sulzer, Philipp; Mayhew, Chris A; Watts, Peter; Jordan, Alfons; Märk, Lukas; Märk, Tilmann D

    2009-12-01

    This work demonstrates for the first time the potential of using recent developments in proton transfer reaction mass spectrometry for the rapid detection and identification of chemical warfare agents (CWAs) in real-time. A high-resolution (m/Deltam up to 8000) and high-sensitivity (approximately 50 cps/ppbv) proton transfer reaction time-of-flight mass spectrometer (PTR-TOF 8000 from Ionicon Analytik GmBH) has been successfully used to detect a number of CWA simulants at room temperature; namely dimethyl methylphosphonate, diethyl methylphosphonate, diisopropyl methylphosphonate, dipropylene glycol monomethyl ether and 2-chloroethyl ethyl sulfide. Importantly, we demonstrate in this paper the potential to identify CWAs with a high level of confidence in complex chemical environments, where multiple threat agents and interferents could also be present in trace amounts, thereby reducing the risk of false positives. Instantaneous detection and identification of trace quantities of chemical threats using proton transfer reaction mass spectrometry could form the basis for a timely warning system capability with greater precision and accuracy than is currently provided by existing analytical technologies.

  19. [Rapid screening and confirmation of non-target pigment in Chinese softshell turtle by liquid chromatography coupled to time of flight mass spectrometry].

    PubMed

    Li, Shiyan; Wang, Yang; Zhou, Fan; Zheng, Chongying; Zhang, Haiqi; He, Zhongyang; He, Xin

    2015-12-01

    A method of non-target pigment screening in Chinese softshell turtle has been established by using liquid chromatography coupled to time of flight mass spectrometry (LC-Q-TOF MS). After being purified by a simple acetonitrile extraction work, the non-target pigment in 20 Chinese softshell turtle samples was detected by liquid chromatography-photodiode array detection (LC-DAD). The S7 sample, which has a strong spectral response, was chosen to extract the mass spectrometry information of the non-target pigment on different gradient elution conditions. In order to get the characteristic molecular mass ion (564.397 73 Da and 564.395 61 Da) of the non-target pigment, qualitative spectral full scan with negative sample was used. The molecular formula generation data and the literature information prompted speculation that the non-target pigment was canthaxanthin with the formula of C40H52O2. By comparing the canthaxanthin standard material MS/MS information, the result was confirmed accurate. A strategy of LC-Q-TOF MS method for the qualitative analysis of unknown compounds is discussed, and the results indicated that the described method can be effectively applied to qualitative analysis for non-target pigment in Chinese softshell turtle. PMID:27097458

  20. Evaluation of relative isotopic abundance measurements in a quadrupole time-of-flight mass spectrometer for elemental composition determination of natural products in traditional Chinese medicine.

    PubMed

    Wu, Zhi-Jun; Huo, Jia-Li; Chen, Jian-Zhong; Li, Na; Fang, Dong-Mei; Chen, Xiao-Zhen; Zhang, Guo-Lin; Wang, Jian-Hua; Xu, Xiao-Ying

    2013-01-01

    The relative isotopic abundance (RIA) measurement errors of a quadrupole time-of-flight (Q-ToF) instrument incorporating analog-to-digital converter detectors were systemically evaluated by stochastically collecting about 200 data in positive ion mass spectrometry (MS) mode. Errors varied with peak intensities at definite spectral acquisition rates but were very close, even if peak intensities changed sharply at different spectral acquisition rates with the same concentration. Intensity thresholds were systematically defined at 1 Hz of spectral acquisition rates. RIA measurement errors were also evaluated using peak area. It seemed that peak area was better adapted for the high-intensity ions while peak intensity was suited for very low-intensity ions. Several known compounds were selected for RIA measurements for product ions in tandem mass spectropmetry (MS/MS) mode. An extract of a representative traditional Chinese medicinal, Paederia scandens was analyzed with high-performance liquid chromatography-electrospray ionization-QToF-MS/MS. The unique elemental compositions of some compounds could not be identified even with exact masses and MS/MS spectra of measured and reference compounds. RIA errors, especially of (M+2)M(-1), provided vital information for determining the elemental composition. PMID:24261081

  1. Laser ablation with resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for determining aromatic lignin volatilization products from biomass.

    PubMed

    Mukarakate, Calvin; Scheer, Adam M; Robichaud, David J; Jarvis, Mark W; David, Donald E; Ellison, G Barney; Nimlos, Mark R; Davis, Mark F

    2011-03-01

    We have designed and developed a laser ablation∕pulsed sample introduction∕mass spectrometry platform that integrates pyrolysis (py) and∕or laser ablation (LA) with resonance-enhanced multiphoton ionization (REMPI) reflectron time-of-flight mass spectrometry (TOFMS). Using this apparatus, we measured lignin volatilization products of untreated biomass materials. Biomass vapors are produced by either a custom-built hot stage pyrolysis reactor or laser ablation using the third harmonic of an Nd:YAG laser (355 nm). The resulting vapors are entrained in a free jet expansion of He, then skimmed and introduced into an ionization region. One color resonance-enhanced multiphoton ionization (1+1 REMPI) is used, resulting in highly selective detection of lignin subunits from complex vapors of biomass materials. The spectra obtained by py-REMPI-TOFMS and LA-REMPI-TOFMS display high selectivity and decreased fragmentation compared to spectra recorded by an electron impact ionization molecular beam mass spectrometer (EI-MBMS). The laser ablation method demonstrates the ability to selectively isolate and volatilize specific tissues within the same plant material and then detect lignin-based products from the vapors with enhanced sensitivity. The identification of select products observed in the LA-REMPI-TOFMS experiment is confirmed by comparing their REMPI wavelength scans with that of known standards. PMID:21456715

  2. Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS)

    PubMed Central

    Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

    2015-01-01

    Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures. PMID:26271045

  3. Evaluation of relative isotopic abundance measurements in a quadrupole time-of-flight mass spectrometer for elemental composition determination of natural products in traditional Chinese medicine.

    PubMed

    Wu, Zhi-Jun; Huo, Jia-Li; Chen, Jian-Zhong; Li, Na; Fang, Dong-Mei; Chen, Xiao-Zhen; Zhang, Guo-Lin; Wang, Jian-Hua; Xu, Xiao-Ying

    2013-01-01

    The relative isotopic abundance (RIA) measurement errors of a quadrupole time-of-flight (Q-ToF) instrument incorporating analog-to-digital converter detectors were systemically evaluated by stochastically collecting about 200 data in positive ion mass spectrometry (MS) mode. Errors varied with peak intensities at definite spectral acquisition rates but were very close, even if peak intensities changed sharply at different spectral acquisition rates with the same concentration. Intensity thresholds were systematically defined at 1 Hz of spectral acquisition rates. RIA measurement errors were also evaluated using peak area. It seemed that peak area was better adapted for the high-intensity ions while peak intensity was suited for very low-intensity ions. Several known compounds were selected for RIA measurements for product ions in tandem mass spectropmetry (MS/MS) mode. An extract of a representative traditional Chinese medicinal, Paederia scandens was analyzed with high-performance liquid chromatography-electrospray ionization-QToF-MS/MS. The unique elemental compositions of some compounds could not be identified even with exact masses and MS/MS spectra of measured and reference compounds. RIA errors, especially of (M+2)M(-1), provided vital information for determining the elemental composition.

  4. Elemental analysis of coal by tandem laser induced breakdown spectroscopy and laser ablation inductively coupled plasma time of flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Dong, Meirong; Oropeza, Dayana; Chirinos, José; González, Jhanis J.; Lu, Jidong; Mao, Xianglei; Russo, Richard E.

    2015-07-01

    The capabilities and analytical benefits of combined LIBS and LA-ICP-MS were evaluated for the analysis of coal samples. The ablation system consisted of a Nd:YAG laser operated 213 nm. A Czerny-turner spectrograph with ICCD detector and time-of-flight based mass spectrometer were utilized for LIBS and ICP-MS detection, respectively. This tandem approach allows simultaneous determination of major and minor elements (C, Si, Ca, Al, Mg), and trace elements (V, Ba, Pb, U, etc.) in the coal samples. The research focused on calibration strategies, specifically the use of univariate and multivariate data analysis on analytical performance. Partial least square regression (PLSR) was shown to minimize and compensate for matrix effects in the emission and mass spectra improving quantitative analysis by LIBS and LA-ICP-MS, respectively. The correlation between measurements from these two techniques demonstrated that mass spectral data combined with LIBS emission measurements by PLSR improved the accuracy and precision for quantitative analysis of trace elements in coal.

  5. Matrix-assisted and polymer-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of low molecular weight polystyrenes and polyethylene glycols.

    PubMed

    Woldegiorgis, Andreas; Löwenhielm, Peter; Björk, Anders; Roeraade, Johan

    2004-01-01

    Recently, matrices based on oligomers of dioxin and thiophene (polymer-assisted laser desorption/ionization (PALDI)) have been described for mass spectrometric (MS) analysis of low molecular weight compounds (Woldegiorgis A, von Kieseritzky F, Dahlstedt E, Hellberg J, Brinck T, Roeraade J. Rapid Commun. Mass Spectrom. 2004; 18: 841-852). In this paper, we report the use of PALDI matrices for low molecular weight polymers. An evaluation with polystyrene and polyethylene glycol showed that no charge transfer ionization occurs. Ionization is mediated through metal ion adduction. Comparison of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) data for two very low molecular weight polymers with data obtained from size-exclusion chromatography (SEC) revealed a systematic difference regarding mean molecular weight and dispersity. Further, the mass spectra obtained with PALDI matrices had a higher signal-to-noise ratio than the spectra obtained with conventional matrices. For polymers with higher molecular weights (>1500 Da), the conventional matrices gave better performance. For evaluation of the MALDI spectra, three non-linear mathematical models were evaluated to model the cumulative distributions of the different oligomers and their maximal values of Mw, Mn and PDI. Models based on sigmoidal or Boltzmann equations proved to be most suitable. Objective modeling tools are necessary to compare different sample and instrumental conditions during method optimization of MALDI analysis of polymers, since the bias between MALDI and SEC data can be misleading.

  6. Applications of proton transfer reaction time-of-flight mass spectrometry for the sensitive and rapid real-time detection of solid high explosives

    NASA Astrophysics Data System (ADS)

    Mayhew, C. A.; Sulzer, P.; Petersson, F.; Haidacher, S.; Jordan, A.; Märk, L.; Watts, P.; Märk, T. D.

    2010-01-01

    Using recent developments in proton transfer reaction mass spectrometry, proof-of-principle investigations are reported here to illustrate the capabilities of detecting solid explosives in real-time. Two proton transfer reaction time-of-flight mass spectrometers (Ionicon Analytik) have been used in this study. One has an enhanced mass resolution (m/[Delta]m up to 8000) and high sensitivity (~50 cps/ppbv). The second has enhanced sensitivity (~250 cps/ppbv) whilst still retaining high resolution capabilities (m/[Delta]m up to 2000). Both of these instruments have been successfully used to identify solid explosives (RDX, TNT, HMX, PETN and Semtex A) by analyzing the headspace above small quantities of samples at room temperature and from trace quantities not visible to the naked eye placed on surfaces. For the trace measurements a simple pre-concentration and thermal desorption technique was devised and used. Importantly, we demonstrate the unambiguous identification of threat agents in complex chemical environments, where multiple threat agents and interferents may be present, thereby eliminating false positives. This is of considerable benefit to security and for the fight against terrorism.

  7. Online analysis of single cyanobacteria and algae cells under nitrogen-limited conditions using aerosol time-of-flight mass spectrometry.

    PubMed

    Cahill, John F; Darlington, Thomas K; Fitzgerald, Christine; Schoepp, Nathan G; Beld, Joris; Burkart, Michael D; Prather, Kimberly A

    2015-08-18

    Metabolomics studies typically perform measurements on populations of whole cells which provide the average representation of a collection of many cells. However, key mechanistic information can be lost using this approach. Investigating chemistry at the single cell level yields a more accurate representation of the diversity of populations within a cell sample; however, this approach has many analytical challenges. In this study, an aerosol time-of-flight mass spectrometer (ATOFMS) was used for rapid analysis of single algae and cyanobacteria cells with diameters ranging from 1 to 8 μm. Cells were aerosolized by nebulization and directly transmitted into the ATOFMS. Whole cells were determined to remain intact inside the instrument through a combination of particle sizing and imaging measurements. Differences in cell populations were observed after perturbing Chlamydomonas reinhardtii cells via nitrogen deprivation. Thousands of single cells were measured over a period of 4 days for nitrogen-replete and nitrogen-limited conditions. A comparison of the single cell mass spectra of the cells sampled under the two conditions revealed an increase in the dipalmitic acid sulfolipid sulfoquinovosyldiacylglycerol (SQDG), a chloroplast membrane lipid, under nitrogen-limited conditions. Single cell peak intensity distributions demonstrate the ability of the ATOFMS to measure metabolic differences of single cells. The ATOFMS provides an unprecedented maximum throughput of 50 Hz, enabling the rapid online measurement of thousands of single cell mass spectra. PMID:26237223

  8. Study of bis(bibenzyls) in bryophytes using electron ionization time-of-flight and electrospray ionization triple-quadrupole mass spectrometry.

    PubMed

    Guo, Huaifang; Xing, Jie; Xie, Chunfeng; Qu, Jianbo; Gao, Yanhui; Lou, Hongxiang

    2007-01-01

    A detailed analysis of mass spectra generated from bis(bibenzyl) compounds in bryophytes under electron ionization time-of-flight (EI-TOF) and electrospray ionization triple-quadrupole (ESI-TQ) mass spectrometry conditions is reported. Proposed structures of the fragment ions were obtained by tracking the functional groups of 15 bis(bibenzyls), the structures of which are similar except for some alkoxyl substituents and linkage sites of biphenyl ether bonds. The elucidation was aided by the use of accurate mass measurements. Attempts have been made to provide rational pathways for the formation of these fragment ions, and a generalized fragmentation mechanism is proposed. The bis(bibenzyls) mentioned in this study include three types according to their structure characteristics, i.e. one biphenyl ether bond (A-type), two biphenyl ether bonds (B-type), one biphenyl ether and one biphenyl bond (C-type). The three types display different EI-MS and ESI-MS/MS product profiles, by which the bis(bibenzyl) type and the number of alkoxyl substituents can be identified. Isomers of bis(bibenzyls) can be differentiated to some extent, while the linkage sites of biphenyl ether bonds are difficult to identify. The structure-fragmentation relationships will facilitate the characterization of other bis(bibenzyls) and this will be of value for the high-throughput screening of novel bis(bibenzyls) in bryophytes.

  9. Nano-liquid chromatography coupled to time-of-flight mass spectrometry for phenolic profiling: a case study in cranberry syrups.

    PubMed

    Contreras, María del Mar; Arráez-Román, David; Fernández-Gutiérrez, Alberto; Segura-Carretero, Antonio

    2015-01-01

    A new method based on nano-liquid chromatography coupled to time-of-flight mass spectrometry (nano-LC-TOF-MS) using lock-mass calibration was developed to facilitate the accurate and routine characterization and quantification of phenolic compounds. Thus, it was applied to study cranberry syrups, in which, using negative ionization mode, a total of nine phenolic compounds were unequivocally identified using standards and 38 tentatively taking into account their retention time, accurate mass (errors<5 ppm) data and isotope pattern, as well as literature. Among them, 13 compounds, belonging to flavonols and iridoids conjugated with phenolic acids, were reported for first time in cranberry or cranberry based-products. The analytical method was also validated using chlorogenic acid, p-coumaric acid, (+)-catechin, (-)-epicatechin, procyanidin A2, quercetin 3-O-glucoside, quercetin 3-O-rhamnoside, quercetin, and myricetin standards. In this way, the analytical method showed adequate linearity, with R(2) above 0.99, and acceptable values of intra- and inter-day repeatability of the retention time and peak area. The detection limits and quantification were between 1.0-15.6 ng mL(-1) and 2.0-62.5 ng mL(-1), respectively. The method can be extended to characterize phenolic compounds in other food and plant matrices, and as well biological samples. PMID:25476399

  10. Direct identification of trypanosomatids by matrix-assisted laser desorption ionization-time of flight mass spectrometry (DIT MALDI-TOF MS).

    PubMed

    Avila, C C; Almeida, F G; Palmisano, G

    2016-08-01

    Accurate and rapid determination of trypanosomatids is essential in epidemiological surveillance and therapeutic studies. Matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS) has been shown to be a useful and powerful technique to identify bacteria, fungi, metazoa and human intact cells with applications in clinical settings. Here, we developed and optimized a MALDI-TOF MS method to profile trypanosomatids. trypanosomatid cells were deposited on a MALDI target plate followed by addition of matrix solution. The plate was then subjected to MALDI-TOF MS measurement to create reference mass spectra library and unknown samples were identified by pattern matching using the BioTyper software tool. Several m/z peaks reproducibly and uniquely identified trypanosomatids species showing the potentials of direct identification of trypanosomatids by MALDI-TOF MS. Moreover, this method discriminated different life stages of Trypanosoma cruzi, epimastigote and bloodstream trypomastigote and Trypanosoma brucei, procyclic and bloodstream. T. cruzi Discrete Typing Units (DTUs) were also discriminated in three clades. However, it was not possible to achieve enough resolution and software-assisted identification at the strain level. Overall, this study shows the importance of MALDI-TOF MS for the direct identification of trypanosomatids and opens new avenues for mass spectrometry-based detection of parasites in biofluids. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27659938

  11. [Rapid screening and confirmation of non-target pigment in Chinese softshell turtle by liquid chromatography coupled to time of flight mass spectrometry].

    PubMed

    Li, Shiyan; Wang, Yang; Zhou, Fan; Zheng, Chongying; Zhang, Haiqi; He, Zhongyang; He, Xin

    2015-12-01

    A method of non-target pigment screening in Chinese softshell turtle has been established by using liquid chromatography coupled to time of flight mass spectrometry (LC-Q-TOF MS). After being purified by a simple acetonitrile extraction work, the non-target pigment in 20 Chinese softshell turtle samples was detected by liquid chromatography-photodiode array detection (LC-DAD). The S7 sample, which has a strong spectral response, was chosen to extract the mass spectrometry information of the non-target pigment on different gradient elution conditions. In order to get the characteristic molecular mass ion (564.397 73 Da and 564.395 61 Da) of the non-target pigment, qualitative spectral full scan with negative sample was used. The molecular formula generation data and the literature information prompted speculation that the non-target pigment was canthaxanthin with the formula of C40H52O2. By comparing the canthaxanthin standard material MS/MS information, the result was confirmed accurate. A strategy of LC-Q-TOF MS method for the qualitative analysis of unknown compounds is discussed, and the results indicated that the described method can be effectively applied to qualitative analysis for non-target pigment in Chinese softshell turtle.

  12. Non-target screening of organic contaminants in marine salts by gas chromatography coupled to high-resolution time-of-flight mass spectrometry.

    PubMed

    Serrano, Roque; Nácher-Mestre, Jaime; Portolés, Tania; Amat, Francisco; Hernández, Félix

    2011-08-15

    Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF MS) has been applied to characterize the organic pollution pattern of marine salt samples collected in saltworks from the Spanish Mediterranean coast. After dissolving the samples in water, a solid-phase extraction was applied reaching with a 250-preconcentration factor. The screening methodology allowed the detection of sample components without any kind of pre-selection of target pollutants. The identity of components detected was established by accurate mass measurements and comparison of experimental full-acquisition spectra with theoretical MS libraries. Several organic pollutants were identified in the samples, like plasticizers - potentially toxic to humans - and fragrances -included within the group of pharmaceuticals and personal care products-, among others. Our results indicate that these contaminants can be found in the marine salt after the crystallization process. GC-TOF MS is a powerful technique for wide-scope screening of (semi)volatile, low-polar organic contaminants, able to investigate the presence of a large number of compounds. Searching of contaminants is not restricted to a target list of compounds. Therefore, unexpected contaminants can be discovered in an efficient way, with better sensitivity and selectivity than other conventional analytical techniques, and making use of the powerful qualitative information provided by full-spectrum acquisition at accurate mass.

  13. [Screening method for 29 forbidden or limited synthetic pigments in cheese by liquid chromatography/quadrupole time-of-flight mass spectrometry].

    PubMed

    Zhao, Yansheng; Yang, Minli; Zhang, Feng; Feng, Feng; Chu, Xiaogang; Dong, Ying

    2011-07-01

    A screening method for 29 forbidden or limited synthetic pigments in cheese samples was established by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF MS). The pigments were extracted by n-hexane/water (3:1, v/v). After extraction, the n-hexane extract, water extract and residue, were obtained. The n-hexane extract was then cleaned-up by gel permeation chromatography (GPC). The water extract was extracted by acetonitrile, and the residue by ammonia water/methanol (1:99, v/v). The results showed that the 29 synthetic pigments with a wide range of polarities were extracted effectively with the recoveries between 70% and 95%, and matched well by Q-TOF MS precision mass searching to the mass spectral library with matching scores between 59. 66 and 99. 47. The quantitative analysis of the 29 pigments was carried out by Target MS/MS. The limits of detection (LODs) for 8 Sudan dyes were 0.4-2.5 micro/kg while for 21 water-soluble synthetic pigments were 20-80 microg/kg. The screening method is suitable for a wide range of synthetic pigments, and can be applied to food samples with proteins and fat in matrix.

  14. Profile of Native N-linked Glycan Structures from Human Serum Using High Performance Liquid Chromatography on a Microfluidic Chip and Time-of-Flight Mass Spectrometry

    PubMed Central

    Chu, Caroline S.; Niñonuevo, Milady R.; Clowers, Brian H.; Perkins, Patrick D.; An, Hyun Joo; Yin, Hongfeng; Killeen, Kevin; Miyamoto, Suzanne; Grimm, Rudolf; Lebrilla, Carlito B.

    2009-01-01

    Protein glycosylation involves the addition of monosaccharides in a stepwise process requiring no glycan template. Therefore, identifying the numerous glycoforms, including isomers, can help elucidate the biological function(s) of particular glycans. A method to assess the diversity of the N-linked oligosaccharides released from human serum without derivatization has been developed using on-line nano-liquid chromatography (nanoLC) and high resolution time-of-flight mass spectrometry. The N-linked oligosaccharides were analyzed with matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT-ICR MS) and microchip liquid chromatography mass spectrometry (HPLC-Chip/TOF MS). Two microfluidic chips were employed, the glycan chip (40 nL enrichment column, 43×0.075 mm ID analytical column) and the high capacity chip (160 nL enrichment column, 140×0.075 mm ID analytical column), both with graphitized carbon as the stationary phase. Both chips offered good sensitivity and reproducibility in separating a heterogeneous mixture of neutral and anionic oligosaccharides between injections. Increasing the length and volume of the enrichment and the analytical columns improved resolution of the peaks. Complex type N-linked oligosaccharides were the most abundant oligosaccharides in human serum accounting for ~96% of the total glycans identified, while hybrid and high mannose type oligosaccharides comprise the remaining ~4%. PMID:19288519

  15. Identification of bioactive peptides in a functional yogurt by micro liquid chromatography time-of-flight mass spectrometry assisted by retention time prediction.

    PubMed

    Kunda, Pradeep B; Benavente, Fernando; Catalá-Clariana, Sergio; Giménez, Estela; Barbosa, José; Sanz-Nebot, Victoria

    2012-03-16

    In this study we used micro liquid chromatography coupled to time-of-flight mass spectrometry (microLC-TOF-MS) for separation and identification of bioactive peptides in a yogurt marketed as an antihypertensive functional food. An appropriate sample clean-up using solid-phase extraction (SPE) allowed detection of a large number of low-molecular-mass bioactive peptides by reversed-phase microLC-TOF-MS. The preliminary identification was solely based on the experimental monoisotopic molecular mass values (M(exp)). Later, we evaluated the correlations between predicted normalized elution time (NET) and experimental normalized retention times (t(r)') values to describe the retention behavior of the proposed sequences. The assistance of retention prediction proved to be useful to improve reliability of the identification, avoiding misinterpretations and solving some identity conflicts. After revision, the identity of only fifty bioactive peptides was confirmed. Significant number of these peptides was reported as angiotensin converting enzyme (ACE) inhibitors and nine of them were antihypertensive. The presence of peptide sequences with other biological activities such as antibacterial, antithrombotic, antioxidant, cell modulation, immune or phagocytosis stimulation, epitopes of B cells and opioid agonists was also confirmed.

  16. Direct bacterial profiling by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry for identification of pathogenic Neisseria.

    PubMed

    Ilina, Elena N; Borovskaya, Alexandra D; Malakhova, Maja M; Vereshchagin, Vladimir A; Kubanova, Anna A; Kruglov, Alexander N; Svistunova, Tatyana S; Gazarian, Anaida O; Maier, Thomas; Kostrzewa, Markus; Govorun, Vadim M

    2009-01-01

    The present study investigates the suitability of direct bacterial profiling as a tool for the identification and subtyping of pathogenic Neisseria. The genus Neisseria includes two human pathogens, Neisseria meningitidis and Neisseria gonorrhoeae, as well as several nonpathogenic Neisseria species. Here, a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry profiling protocol was optimized using a laboratory strain of E. coli DH5alpha to guarantee high quality and reproducible results. Subsequently, mass spectra for both laboratory and clinical strains of N. gonorrhoeae, N. meningitidis, and several nonpathogenic Neisseria species were collected. Significant interspecies differences but little intraspecies diversity were revealed by means of a visual inspection and bioinformatics examination using the MALDI BioTyper software. Cluster analysis successfully separated mass spectra collected from three groups that corresponded to N. gonorrhoeae, N. meningitidis, and nonpathogenic Neisseria isolates. Requiring only one bacterial colony for testing and using a fast and easy measuring protocol, this approach represents a powerful tool for the rapid identification of pathogenic Neisseria and can be adopted for other microorganisms.

  17. Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry.

    PubMed

    Beddows, David C S; Donovan, Robert J; Harrison, Roy M; Heal, Mathew R; Kinnersley, Robert P; King, Martin D; Nicholson, David H; Thompson, Katherine C

    2004-02-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was used to determine, in real time, the size and chemical composition of individual particles in the atmosphere at the remote inland site of Eskdalemuir, Scotland. A total of 51,980 particles, in the size range 0.3-7.4 microm, were detected between the 25th and 30th June 2001. Rapid changes in the number density, size and chemical composition of the atmospheric aerosol were observed. These changes are attributed to two distinct types of air mass; a polluted air mass that had passed over the British mainland before reaching Eskdalemuir, interposed between two cleaner air masses that had arrived directly from the sea. Such changes in the background aerosol could clearly be very important to studies of urban aerosols and attempts at source apportionment. The results of an objective method of data analysis are presented. Correlations were sought between the occurrence of: lithium, potassium, rubidium, caesium, beryllium, strontium, barium, ammonium, amines, nitrate, nitrite, boron, mercury, sulfate, phosphate, fluorine, chlorine, bromine, iodine and carbon (both elemental and organic hydrocarbon) in both fine (d < 2.5 microm) and coarse (d > 2.5 microm) particle fractions. Several previously unreported correlations were observed, for instance between the elements lithium, beryllium and boron. The results suggest that about 2 in 3 of all fine particles (by number rather than by mass), and 1 in 2 of all coarse particles containing carbon, consisted of elemental carbon rather than organic hydrocarbon (although a bias in the sensitivity of the ATOFMS could have affected these numbers). The ratio of the number of coarse particles containing nitrate anions to the number of particles containing chloride anions exceeded unity when the air mass had travelled over the British mainland. The analysis also illustrates that an air mass of marine origin that had travelled slowly over agricultural land can accumulate amines and

  18. Rosetta/COSIMA: Laboratory time-of-flight secondary ion mass spectra of PAHs for in-situ detection in the cometary solid organic matter

    NASA Astrophysics Data System (ADS)

    Bardyn, A.; Briois, C.; Cottin, H.; Fray, N.; LeRoy, L.; Thirkell, L.; Hilchenbach, M.

    2014-07-01

    ESA's spacecraft called ROSETTA will reach the comet 67P/Churyumov- Gerasimenko in August 2014. During the escort phase of the mission, beginning after the lander (Philae) is released, the COmetary Secondary Ion Mass Analyzer (COSIMA) [1] carried on board will collect and analyse dust grains in the cometary coma. COSIMA is a time-of-flight secondary ion mass spectrometer (TOF-SIMS) with a high mass resolution m/Δ m of 1400 at mass m=100 amu (from FWHM) and mass range from 1 to 3500 amu. The investigations performed by COSIMA on solid cometary grains are aimed to analyze in situ their molecular, elemental, and isotopic composition. The spectra obtained with COSIMA, will be a combination of mass peaks of mineral and organic elements. The organics are expected to be minor peaks, making their identification not simple. To prepare for the future COSIMA spectra interpretation, the COSIMA team members have started to establish a library database of standardized mass spectra [2,3]. High statistics of positive and negative spectra of the samples were then taken in order to get molecular structure information. Polycyclic Aromatic Hydrocarbons (PAHs) are organic macromolecules that could survive harsh radiation environment. They are suspected to be responsible for unidentified infrared bands observed in diverse astrophysical environments. Many attempts were made to demonstrate the presence of PAHs in comets. Tentative attributions of fluorescence emission bands have been made of spectra taken during the Vega-2 mission [4,5], and recently on Stardust samples returned [6]. In this work, we have used the COSIMA prototype based in Orléans to analyze PAHs and alkanes molecules deposition on gold targets.

  19. Detection of aqueous phase chemical warfare agent degradation products by negative mode ion mobility time-of-flight mass spectrometry [IM(tof)MS].

    PubMed

    Steiner, Wes E; Harden, Charles S; Hong, Feng; Klopsch, Steve J; Hill, Herbert H; McHugh, Vincent M

    2006-02-01

    The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined. Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified reference materials (CRM) of CWA degradation products for the detection of Schedule 1, 2, or 3 toxic chemicals or their precursors as defined by the chemical warfare convention (CWC) treaty verification were used in this study. A mixture of six G-series nerve related CWA degradation products (EMPA, IMPA, EHEP, IHEP, CHMPA, and PMPA) and their related collision induced dissociation (CID) fragment ions (MPA and EPA) were found in each case to be clearly resolved and detected using the IM(tof)MS instrument in negative ion monitoring mode. Corresponding ions, masses, drift times, K(o) values, and signal intensities for each of the CWA degradation products are reported. PMID:16413205

  20. Use of time-of-flight mass spectrometry for large screening of organic pollutants in surface waters and soils from a rice production area in Colombia.

    PubMed

    Hernández, F; Portolés, T; Ibáñez, M; Bustos-López, M C; Díaz, R; Botero-Coy, A M; Fuentes, C L; Peñuela, G

    2012-11-15

    The irrigate district of Usosaldaña, an important agricultural area in Colombia mainly devoted to rice crop production, is subjected to an intensive use of pesticides. Monitoring these compounds is necessary to know the impact of phytosanitary products in the different environmental compartments. In this work, surface water and soil samples from different sites of this area have been analyzed by applying an analytical methodology for large screening based on the use of time-of-flight mass spectrometry (TOF MS) hyphenated to liquid chromatography (LC) and gas chromatography (GC). Several pesticides were detected and unequivocally identified, such as the herbicides atrazine, diuron or clomazone. Some of their main metabolites and/or transformation products (TPs) like deethylatrazine (DEA), deisopropylatrazine (DIA) and 3,4-dichloroaniline were also identified in the samples. Among fungicides, carbendazim, azoxystrobin, propiconazole and epoxiconazole were the most frequently detected. Insecticides such as thiacloprid, or p,p'-DDT metabolites (p,p'-DDD and p,p'-DDE) were also found. Thanks to the accurate-mass full-spectrum acquisition in TOF MS it was feasible to widen the number of compounds to be investigated to other families of contaminants. This allowed the detection of emerging contaminants, such as the antioxidant 3,5-di-tertbutyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), or the solar filter benzophenone, among others.

  1. Multiresidue analysis of plant growth regulators in grapes by triple quadrupole and quadrupole-time of flight-based liquid chromatography/mass spectrometry.

    PubMed

    Oulkar, Dasharath P; Banerjee, Kaushik; Kulkarni, Sunil

    2011-01-01

    A selective and sensitive LC-MS/MS method is presented for simultaneous determination of 12 plant growth regulators, viz., indol-3-acetic acid, indol-3-butyric acid, kinetin, zeatin, 6-benzyl aminopurine, gibberellic acid, abscisic acid, chlormequat chloride, forchlorfenuron, paclobutrazole, daminozide, and 2,4-dichlorophenoxy acetic acid, in bud sprouts and grape berries. The sample preparation method involved extraction of homogenized sample (5 g) with 40 mL methanol (80%), and final determination was by LC-MS/MS in the multiple reaction monitoring (MRM) mode with time segmentation for quantification supported by complementary analysis by quadrupole-time of flight (Q-TOF) MS with targeted high-resolution MS/MS scanning for confirmatory identification based on accurate mass measurements. The recovery of the test compounds ranged within 90-107% with precision RSD less than 5% (n = 6). The method could be successfully applied in analyzing incurred residue samples, and the strength of accurate mass analysis could be utilized in identifying the compounds in cases where the qualifier MRM ions were absent or at an S/N less than 3:1 due to low concentrations.

  2. AMINO ACID ANALYSES OF THE ANTARCTIC CM2 METEORITES ALH 83100 AND LEW 90500 USING LIQUID CHROMATOGRAPHY-TIME OF FLIGHT-MASS SPECTROMETRY

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Dworkin, J. P.; Aubrey, A.; Botta, O.; Doty, J. H., III; Bada, J. L.

    2001-01-01

    The investigation of organic compounds in primitive carbonaceous meteorites provides a record of the chemical processes that occurred in the early solar system. In particular, amino acids have been shown to be potential indicators in tracing the nature of carbonaceous chondrite parent bodies [ 13. The delivery of amino acids by carbonaceous chondrites to the early Earth could have been any important source of the Earth's prebiotic organic inventory [2]. Over 80 different amino acids have been detected in the Murchison CM2 meteorite, most of them completely non-existent in the terrestrial biosphere [3]. We have optimized a new liquid chromatography-time-of-flight-mass spectrometry (LC-ToF-MS) technique coupled with OPAMAC derivatization in order to detect amino acids in meteorite extracts by UV fluorescence and exact mass simultaneously. The detection limit of the LC-ToF-MS instrument for amino acids is at least 3 orders of magnitude lower than traditional GC-MS techniques. Here we report on the first analyses of amino acids and their enantiomeric abundances in the CM2 carbonaceous meteorites ALH 83100, LEW 90500, and Murchison using this new LC-ToF-MS instrument configuration. Amino acid analyses of any kind for the CM meteorite ALH 83100 have not previously been reported.

  3. Metabolites identification of Huo Luo Xiao Ling Dan in rat urine by UPLC coupled with electrospray ionization time-of-flight mass spectrometry.

    PubMed

    Wang, Fenrong; Wu, Yun; Ai, Yu; Bian, Qiaoxia; Ma, Wen; Lee, David Y-W; Dai, Ronghua

    2016-03-01

    Huo Luo Xiao Ling Dan (HLXLD), a Chinese herbal formula, is used in folk medicine for the treatment of arthritis and other chronic inflammatory diseases. However, the in vivo integrated metabolism of its multiple components remains unknown. In this paper, an ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS) method was developed for detection and identification of HLXLD metabolites in rat urine at high and normal clinical dosages. The prototype constituents and their metabolites in urine were analyzed. The mass measurements were accurate within 8 ppm, and subsequent fragment ions offered higher quality structural information for interpretation of the fragmentation pathways of various compounds. A total of 85 compounds were detected in high dosages urine samples by a highly sensitive extracted ion chromatograms method, including 31 parent compounds and 54 metabolites. Our results indicated that phase 2 reactions (e.g. glucuronidation, glutathionidation and sulfation) were the main metabolic pathways of lactones, alkaloids and flavones, while phase I reactions (e.g. hydrogenation and hydroxylation) were the major metabolic reaction for coumarins, paeoniflorin and iridoids. This investigation provided important structural information on the metabolism of HLXLD and provided scientific evidence to obtain a more comprehensive metabolic profile.

  4. Disposable polymeric high-density nanovial arrays for matrix assisted laser desorption/ionization-time of flight-mass spectrometry: I. Microstructure development and manufacturing.

    PubMed

    Marko-Varga, G; Ekstrom, S; Heildin, G; Nilsson, J; Laureli, T

    2001-10-01

    In order to meet the expected enormous demand for mass spectrometry (MS) throughput as a result of the current efforts to completely map the human proteome, this paper presents a new concept for low-cost high-throughput protein identification by matrix assisted laser desorption/ionization-time of flight-(MALDI-TOF)-MS peptide mapping using disposable polymeric high-density nanovial MALDI target plates. By means of microfabrication technology precision engineered nanovial arrays are fabricated in polymer substrates such as polymethylmethacrylate (PMMA) and polycarbonate (PC). The target plate fabrication processes investigated were precision micromilling, cold embossing and injection moulding (work in progress). Nanovial dimensions were 300, 400 or 500 microm. Typical array densities were 165 nanovials/cm2, which corresponds to 3,300 vials on a full Applied Biosystems MALDI target plate. Obtained MALDI data displayed equal mass resolution, accuracy, signal intensity for peptide standards as compared to high-density silicon nanovial arrays previously reported by our group [7], as well as conventional stainless steel or gold targets. PMID:11700729

  5. Chemical fingerprint and metabolic profile analysis of ethyl acetate fraction of Gastrodia elata by ultra performance liquid chromatography/quadrupole-time of flight mass spectrometry.

    PubMed

    Tang, Chunlan; Wang, Li; Liu, Xinxin; Cheng, Mengchun; Xiao, Hongbin

    2016-02-01

    The chemical fingerprint and metabolic profile of traditional Chinese medicine is very complicated and has been a great challenge. In the present study, chemical fingerprint of ethyl acetate fraction of Gastrodia elata (EtAcGE) and metabolic profile of rat plasma sample after intragastric administration of EtAcGE (2.5g/kg) were investigated using ultra-high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UPLC/Q-TOF MS). A total of 38 chemical constituents of EtAcGE were identified by comparing their retention time, accurate molecular mass and characteristic fragment ions with those of references, or tentatively characterized by comparing molecular formula, fragment ions with that of known compound or information available in literature. And 40 compounds were detected in dosed rat plasma sample, including 16 prototypes and 24 metabolites underwent metabolic process of glucuronidation, glucosylation, sulfation, methylation, hydroxylation, dehydrogenation or mixed modes. The metabolic "soft spots" was hydroxyl or carboxy group. This is the first research for chemical fingerprint and metabolic profile of EtAcGE, which lay a foundation for the further investigation of EtAcGE. PMID:26621783

  6. Liquid chromatography/quadrupole-time-of-flight mass spectrometry with metabolic profiling of human urine as a tool for environmental analysis of dextromethorphan.

    PubMed

    Thurman, E Michael; Ferrer, Imma

    2012-10-12

    We use the combination of liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF-MS) and urine metabolic profiling to find and identify the metabolites of dextromethorphan, a common over-the-counter (OTC) cough suppressant. Next, we use the combination of ion masses, their MS/MS fragmentation, and retention times to determine dextromethorphan and its metabolites in surface water impacted by wastewater. Prior to this study, neither dextromethorphan nor its metabolites have been reported in surface water; in spite of its common use in over 100 various OTC medications. We found that the concentration of the dextrorphan metabolite in surface water greatly exceeded the parent compound by factors of 5-10 times, which reflects the urine profile, where parent compound is approximately <2% of the total excreted drug based on ion intensities. Urine profiling also indicated that glucuronide metabolites are major phase 2 products (92% of the total) in urine and then are completely hydrolyzed in wastewater to dextrorphan and N-demethyldextrorphan, which are phase 1 metabolites-a "kind of reversal" of human metabolism.

  7. Detection and identification of diterpenoid alkaloids, isoflavonoids and saponins in Qifu decoction and rat plasma by liquid chromatography-time-of-flight mass spectrometry.

    PubMed

    Tan, Guangguo; Jing, Jing; Zhu, Zhenyu; Lou, Ziyang; Li, Wuhong; Zhao, Liang; Zhang, Guoqing; Chai, Yifeng

    2012-02-01

    A liquid chromatography-time-of-flight mass spectrometric (LC-TOFMS) method has been developed for analysis of components in Qifu decoction (QFD), a traditional Chinese medical formula consisting of Radix Astragali and Acontium carmichaeli, and in rat plasma after oral administration. Based on accurate mass measurements within 3 ppm error for each molecular ion and subsequent fragment ions of TOFMS, as well as matching of empirical molecular formulae with those of published components in the in-house chemical library, a total of 44 major components including 21 diterpenoid alkaloids, 12 flavonoids and 11 saponins were identified in QFD. After oral administration of QFD, 22 components in rat plasma were detected and identified by comparing and contrasting the constituents measured in QFD with those in the plasma samples. The results provided valuable chemical information for further pharmacology and active mechanism research on QFD. LC-TOFMS was also applied for the comparison of relative peak area of major active components between QFD and the single herb extracts. The concentration ratios of major saponins detected in the crude herb Radix Astragali were found to be different from those in QFD. The experimental data indicated that the decocting process could result in differences in the amounts of active components. PMID:21594877

  8. Multiresidue analysis of beta-agonists in pork by coupling polymer monolith microextraction to electrospray quadrupole time-of-flight mass spectrometry.

    PubMed

    Huang, Jing-Fang; Zhang, Hui-Juan; Lin, Bo; Yu, Qiong-Wei; Feng, Yu-Qi

    2007-01-01

    A novel method of polymer monolith microextraction (PMME) using poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith combined with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF MS) was developed for the rapid and sensitive determination of beta-agonists in pork samples. The conditions of PMME were optimized for the improvement of extraction efficiency and reduction of the matrix interferences from pork. Under the optimal condition, the eluate solution allowed direct analysis by mass spectrometry. In the positive ion mode and in the multiple reaction monitoring (MRM) mode, the limits of detection (LODs) for beta-agonists were found to be 0.08 ng/g (clenbuterol, CLB), 0.18 ng/g (salbutamol, SBTM) and 0.26 ng/g (terbutaline, TBTL) in pork, respectively, with good inter- and intra-day precisions (2-10% for CLB, 11-23% for SBTM and 4-16% for TBTL). The proposed PMME/ESI-QTOF MS method was successfully applied to the determination of beta-agonist residues in thirteen real samples, and the positive samples were confirmed according to the identification points (IPs) system defined by Commission Decision 2002/657/EC. To investigate the matrix effect, the proposed method was compared with PMME-HPLC/ESI-QTOF MS and the slight decrease in sensitivity of PMME/ESI-QTOF MS was ascribed to the inter-analyte ion suppression.

  9. Structural Characterization of New Peptide Variants Produced by Cyanobacteria from the Brazilian Atlantic Coastal Forest Using Liquid Chromatography Coupled to Quadrupole Time-of-Flight Tandem Mass Spectrometry.

    PubMed

    Sanz, Miriam; Andreote, Ana Paula Dini; Fiore, Marli Fatima; Dörr, Felipe Augusto; Pinto, Ernani

    2015-06-18

    Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins) were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp.).

  10. Monitoring of volatile compound emissions during dry anaerobic digestion of the Organic Fraction of Municipal Solid Waste by Proton Transfer Reaction Time-of-Flight Mass Spectrometry.

    PubMed

    Papurello, Davide; Soukoulis, Christos; Schuhfried, Erna; Cappellin, Luca; Gasperi, Flavia; Silvestri, Silvia; Santarelli, Massimo; Biasioli, Franco

    2012-12-01

    Volatile Organic Compounds (VOCs) formed during anaerobic digestion of aerobically pre-treated Organic Fraction of Municipal Solid Waste (OFMSW), have been monitored over a 30 day period by a direct injection mass spectrometric technique: Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). Most of the tentatively identified compounds exhibited a double-peaked emission pattern which is probably the combined result from the volatilization or oxidation of the biomass-inherited organic compounds and the microbial degradation of organic substrates. Of the sulfur compounds, hydrogen sulfide had the highest accumulative production. Alkylthiols were the predominant sulfur organic compounds, reaching their maximum levels during the last stage of the process. H(2)S formation seems to be influenced by the metabolic reactions that the sulfur organic compounds undergo, such as a methanogenesis induced mechanism i.e. an amino acid degradation/sulfate reduction. Comparison of different batches indicates that PTR-ToF-MS is a suitable tool providing information for rapid in situ bioprocess monitoring. PMID:23079412

  11. Evaluation of the Andromas Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Aerobically Growing Gram-Positive Bacilli

    PubMed Central

    Farfour, E.; Leto, J.; Barritault, M.; Barberis, C.; Meyer, J.; Dauphin, B.; Le Guern, A.-S.; Leflèche, A.; Badell, E.; Guiso, N.; Leclercq, A.; Le Monnier, A.; Lecuit, M.; Rodriguez-Nava, V.; Bergeron, E.; Raymond, J.; Vimont, S.; Bille, E.; Carbonnelle, E.; Guet-Revillet, H.; Lécuyer, H.; Beretti, J.-L.; Vay, C.; Berche, P.; Ferroni, A.; Nassif, X.

    2012-01-01

    Matrix-associated laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a rapid and simple microbial identification method. Previous reports using the Biotyper system suggested that this technique requires a preliminary extraction step to identify Gram-positive rods (GPRs), a technical issue that may limit the routine use of this technique to identify pathogenic GPRs in the clinical setting. We tested the accuracy of the MALDI-TOF MS Andromas strategy to identify a set of 659 GPR isolates representing 16 bacterial genera and 72 species by the direct colony method. This bacterial collection included 40 C. diphtheriae, 13 C. pseudotuberculosis, 19 C. ulcerans, and 270 other Corynebacterium isolates, 32 L. monocytogenes and 24 other Listeria isolates, 46 Nocardia, 75 Actinomyces, 18 Actinobaculum, 11 Propionibacterium acnes, 18 Propionibacterium avidum, 30 Lactobacillus, 21 Bacillus, 2 Rhodococcus equi, 2 Erysipelothrix rhusiopathiae, and 38 other GPR isolates, all identified by reference techniques. Totals of 98.5% and 1.2% of non-Listeria GPR isolates were identified to the species or genus level, respectively. Except for L. grayi isolates that were identified to the species level, all other Listeria isolates were identified to the genus level because of highly similar spectra. These data demonstrate that rapid identification of pathogenic GPRs can be obtained without an extraction step by MALDI-TOF mass spectrometry. PMID:22692743

  12. Simultaneous thermogravimetric modulated beam mass spectrometry and time-of-flight velocity spectra measurements of thermal decomposition products from HMX and RDX

    SciTech Connect

    Behrens, R. Jr.

    1987-01-01

    Simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and time-of-flight (TOF) velocity spectra measurements of the time-dependent thermal decomposition products from HMX and RDX show two primary reaction channels. One is a condensed phase autocatalytic reaction that produces N/sub 2/O, H/sub 2/CO, 1-nitoso-3,5,7-trinitro-1,3,5,7-tetrazacyclooctane, and a hydrocarbon-like nonvolatile residue (NVR) as its final products. The other is a gas phase reaction that produces NO/sub 2/, H/sub 2/O, NO and hydroxy-s-triazine as its final products. The catalyst in the condensed phase reaction is probably formaldehyde, the NVR, or both. The gas phase channel appears to be a chain reaction that may be initiated by the abstraction of a hydrogen atom from a CH/sub 2/ group. Under the conditions of these experiments, the HMX decomposes only through the condensed phase channel and the RDX decomposes through both channels. To assure that only thermal decomposition products are measured with the mass spectrometer, the ion fragmentation of HMX was measured as a function of electron energy. Ion fragmentation of HMX was observed down to 12.4 eV indicating that appearance potential measurements do not eliminate ion signals from ion fragmentation of the HMX reactant.

  13. Global detection and identification of components from crude and processed traditional Chinese medicine by liquid chromatography connected with hybrid ion trap and time-of-flight-mass spectrometry.

    PubMed

    Cao, Gang; Zhang, Chengrong; Zhang, Yun; Cong, Xiaodong; Cai, Hao; Cai, Baochang; Li, Xiaomeng; Yao, Jinting

    2011-08-01

    We herein present a chemical profiling method to efficiently process the information acquired by ultra fast liquid chromatography (UFLC)-electrospray ionization source in combination with hybrid ion trap and high-resolution time-of-flight mass spectrometry (UFLC-(ESI)-IT-TOF/MS), facilitating the structural determination of serial components contained in crude or processed traditional Chinese medicine (TCM). Under the optimized UFLC and IT-TOF-MS(n) conditions, over 39 compounds were separated and detected in crude or processed Fructus corni within 25 min. The components were identified by comparing the mass spectra and retention time with reference compounds, or tentatively assigned by elucidating low-energy collision-induced dissociation (CID) fragment ions and matching empirical molecular formula with that of the published compounds. Several factors in the processing procedure were examined. The experimental results demonstrate that the chemical reactions that occurred in the processing procedure can be used to elucidate the processed mechanism of F. corni, which is regularly affected by the processing conditions. This study provides a novel approach and methodology to identify the complicated components from various complex mixtures such as crude TCM, processed TCM, and biological samples. It can be used as a valid analytical method for further understanding the processing mechanism of TCM, along with the intrinsic quality control of TCM and its processed product.

  14. [[Molecular composition of saturated hydrocarbons in diesels by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry

    PubMed

    Niu, Luna; Liu, Zelong; Zhou, Jian; Cai, Xinheng; Tian, Songbai

    2014-11-01

    An analytical method for separation and identification of the saturated hydrocarbons in diesels at molecular level by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC x GC-TOF MS)was established. The saturated hydrocarbons were pre-separated from diesel samples by solid phase extraction before GC x GC-TOF MS analysis. More than 1,000 individual compounds (including paraffins, naphthenes and ole- fins) in coker diesel were tentatively identified based on NIST library search, mass spectrum resolution, boiling point distribution law and separation characteristics. Normal paraffins showed great regularity and could be identified easily through the relative position with pristane and phytane. The cyclic alkanes arranged above paraffins with the increasing number of rings. The normal alkyl cyclohexanes and cyclopentanes were well distinguished due to the difference of their polarity. Normal α-olefins which were often neglected in the past were also identified. With the support of the above-introduced identification, the distribution by structural type and carbon number were presented using peak area normalization. This analytical method was suc- cessfully used to investigate the molecular composition of saturated fractions in different diesel samples. All the results indicated that the molecular compositions of saturates in catalytic cracking diesel and coker diesel were significantly different because of the processing mechanism. This method provided technical support for the characterization of saturated hydrocar- bons in diesels and the investigation of processing mechanism. PMID:25764659

  15. Identification of metabolites of geniposide in rat urine using ultra-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

    PubMed

    Han, Han; Yang, Li; Xu, Ying; Ding, Yue; Bligh, S W Annie; Zhang, Tong; Wang, Zhengtao

    2011-11-15

    Geniposide, an iridoid glycoside, is an important and characteristic compound in the fruits of Gardenia jasminoides Ellis, a commonly used medicinal herb in Chinese traditional and folk medicine for the treatment of inflammation and jaundice. However, few studies have been carried out on the metabolism of geniposide. In this study, we have established a rapid and sensitive method using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC/ESI-QTOF-MS) for analysis of the metabolic profile of geniposide in rat urine after oral administration. A total of ten metabolites were detected and identified by comparing their fragmentation patterns with that of geniposide using Metabolynx™ and MassFragment™ software tools. The results revealed that the principal metabolism pathways of geniposide in rat occurred after deglycosylation of the irdoid glycoside take place and this is followed by glucuronidation and the pyran-ring cleavages. The major metabolite, the glucuronic acid conjugate of genipin as observed in vivo, was further confirmed by the in vitro enzymatic study. The results of this work have demonstrated the feasibility of the UPLC/ESI-QTOF-MS approach for rapid and reliable characterization of metabolites from iridoid compounds. PMID:22006398

  16. Comprehensive two-dimensional gas chromatography time of flight mass spectrometry (GC×GC-TOFMS) for environmental forensic investigations in developing countries.

    PubMed

    de Vos, Jayne; Dixon, Roger; Vermeulen, Gerhard; Gorst-Allman, Peter; Cochran, Jack; Rohwer, Egmont; Focant, Jean-Francois

    2011-02-01

    The disposal and dumping of toxic waste is a matter of growing concern in developing countries, including South Africa. Frequently these countries do not possess access to gas chromatography-high resolution mass spectrometry (GC-HRMS) for the determination of persistent organic pollutants (POPs). This publication describes an alternative approach to the investigation of toxic waste using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC×GC-TOFMS). The technology permits both comprehensive screening of toxic samples for numerous classes of organic pollutants and also quantitative analysis for the individual compounds. This paper describes the use of this technique by analysing samples obtained from a hazardous waste treatment facility in South Africa. After sampling and extraction the samples were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and four dioxin-like non-ortho substituted polychlorinated biphenyls (PCBs). The quantitative values, as well as detection limits, obtained using the GC×GC-TOFMS methodology compares well with those obtained using GC-HRMS; the accepted benchmark technology for this analysis. Although GC×GC-TOFMS is not a target compound analytical technique (as is GC-HRMS), it is possible to obtain information on numerous other classes of organic pollutants present in the samples in one analytical run. This is not possible with GC-HRMS. Several different column combinations have been investigated for handling very complex waste samples and suggestions are presented for the most suitable combination. PMID:21236466

  17. Analysis of veterinary drug and pesticide residues in animal feed by high-resolution mass spectrometry: comparison between time-of-flight and Orbitrap.

    PubMed

    Gómez-Pérez, María Luz; Romero-González, Roberto; Martínez Vidal, José Luis; Garrido Frenich, Antonia

    2015-01-01

    The use of medium-high-resolution mass spectrometers (M-HRMS) provides many advantages in multi-residue analysis. A comparison between two mass spectrometers, medium-resolution (MRMS) time-of-flight (TOF) and high-resolution (HRMS) Orbitrap, has been carried out for the analysis of toxic compounds in animal feed. More than 300 compounds belonging to several classes of veterinary drugs (VDs) and pesticides have been determined in different animal feed samples using a generic extraction method. The use of a clean-up procedure has been evaluated in both instruments, and several validation parameters have been established, such as the matrix effect, linearity, recovery and sensitivity. Finally, both instruments have been used during the analysis of 18 different feed samples (including chicken, hen, rabbit and horse). Some VDs (sulfadiazine, trimethoprim, robenidine and monensin sodium) and one pesticide (chlorpyrifos) have been identified. In general, better results were obtained using the Orbitrap, such as sensitivity (1-12.5 µg kg(-1)) and recovery values (60-125%). Moreover, this analyser had several software tools, which reduced the time for data processing and were easy to use, performing quick screening for more than 450 compounds in less than 5 min. However, some disadvantages such as the high cost and a decrease in the number of detected compounds at low concentrations must be taken into account.

  18. Liquid chromatography/quadrupole-time-of-flight mass spectrometry with metabolic profiling of human urine as a tool for environmental analysis of dextromethorphan.

    PubMed

    Thurman, E Michael; Ferrer, Imma

    2012-10-12

    We use the combination of liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/Q-TOF-MS) and urine metabolic profiling to find and identify the metabolites of dextromethorphan, a common over-the-counter (OTC) cough suppressant. Next, we use the combination of ion masses, their MS/MS fragmentation, and retention times to determine dextromethorphan and its metabolites in surface water impacted by wastewater. Prior to this study, neither dextromethorphan nor its metabolites have been reported in surface water; in spite of its common use in over 100 various OTC medications. We found that the concentration of the dextrorphan metabolite in surface water greatly exceeded the parent compound by factors of 5-10 times, which reflects the urine profile, where parent compound is approximately <2% of the total excreted drug based on ion intensities. Urine profiling also indicated that glucuronide metabolites are major phase 2 products (92% of the total) in urine and then are completely hydrolyzed in wastewater to dextrorphan and N-demethyldextrorphan, which are phase 1 metabolites-a "kind of reversal" of human metabolism. PMID:22443892

  19. Identification of in vitro and in vivo human metabolites of the new psychoactive substance nitracaine by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

    PubMed

    Negreira, Noelia; Kinyua, Juliet; De Brabanter, Nik; Maudens, Kristof; van Nuijs, Alexander L N

    2016-07-01

    The purpose of this work was to investigate the in vitro metabolism of nitracaine, a new psychoactive substance, using human liver microsome incubations, to evaluate the cytochrome P450 (CYP) enzyme isoforms responsible for the phase-I metabolism and to compare the information from the in vitro experiments with data resulting from an authentic user's urine sample. Accurate mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and were used in the structural identification of metabolites. Two major and three minor phase-I metabolites were identified from the in vitro experiments. The observed phase-I metabolites were formed through N-deethylation, N,N-deethylation, N-hydroxylation, and de-esterification, with CYP2B6 and CYP2C19 being the main enzymes catalyzing their formation. One glucuronidated product was identified in the phase-II metabolism experiments. All of these metabolites are reported for the first time in this study except the N-deethylation product. All the in vitro metabolites except the minor N,N-deethylation product were also present in the human urine sample, thus demonstrating the reliability of the in vitro experiments in the prediction of the in vivo metabolism of nitracaine. In addition to the metabolites, three transformation products (p-nitrobenzoic acid, p-aminobenzoic acid, and 3-(diethylamino)-2,2-dimethylpropan-1-ol) were identified, as well as several glucuronides and glutamine derived of them. PMID:27185541

  20. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria.

    PubMed

    Ojima-Kato, Teruyo; Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources.

  1. Phenolic profiling of the skin, pulp and seeds of Albariño grapes using hybrid quadrupole time-of-flight and triple-quadrupole mass spectrometry.

    PubMed

    Di Lecce, Giuseppe; Arranz, Sara; Jáuregui, Olga; Tresserra-Rimbau, Anna; Quifer-Rada, Paola; Lamuela-Raventós, Rosa M

    2014-02-15

    This paper describes for the first time a complete characterisation of the phenolic compounds in different anatomical parts of the Albariño grape. The application of high-performance liquid chromatography coupled with two complementary techniques, hybrid quadrupole time-of-flight and triple-quadrupole mass spectrometry, allowed the phenolic composition of the Albariño grape to be unambiguously identified and quantified. A more complete phenolic profile was obtained by product ion and precursor ion scans, while a neutral loss scan at 152 u enabled a fast screening of procyanidin dimers, trimers and their galloylated derivatives. The compounds were confirmed by accurate mass measurements in QqToF-MS and QqToF-MS/MS modes at high resolution, and good fits were obtained for all investigated ions, with errors ranging from 0.2 to 4.5 mDa. To the best of our knowledge, two flavanol monomer hexosides were detected in the grape berry for the first time.

  2. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria

    PubMed Central

    Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources. PMID:27442502

  3. Structural Characterization of New Peptide Variants Produced by Cyanobacteria from the Brazilian Atlantic Coastal Forest Using Liquid Chromatography Coupled to Quadrupole Time-of-Flight Tandem Mass Spectrometry

    PubMed Central

    Sanz, Miriam; Andreote, Ana Paula Dini; Fiore, Marli Fatima; Dörr, Felipe Augusto; Pinto, Ernani

    2015-01-01

    Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins) were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp.). PMID:26096276

  4. Chemical fingerprint and metabolic profile analysis of ethyl acetate fraction of Gastrodia elata by ultra performance liquid chromatography/quadrupole-time of flight mass spectrometry.

    PubMed

    Tang, Chunlan; Wang, Li; Liu, Xinxin; Cheng, Mengchun; Xiao, Hongbin

    2016-02-01

    The chemical fingerprint and metabolic profile of traditional Chinese medicine is very complicated and has been a great challenge. In the present study, chemical fingerprint of ethyl acetate fraction of Gastrodia elata (EtAcGE) and metabolic profile of rat plasma sample after intragastric administration of EtAcGE (2.5g/kg) were investigated using ultra-high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UPLC/Q-TOF MS). A total of 38 chemical constituents of EtAcGE were identified by comparing their retention time, accurate molecular mass and characteristic fragment ions with those of references, or tentatively characterized by comparing molecular formula, fragment ions with that of known compound or information available in literature. And 40 compounds were detected in dosed rat plasma sample, including 16 prototypes and 24 metabolites underwent metabolic process of glucuronidation, glucosylation, sulfation, methylation, hydroxylation, dehydrogenation or mixed modes. The metabolic "soft spots" was hydroxyl or carboxy group. This is the first research for chemical fingerprint and metabolic profile of EtAcGE, which lay a foundation for the further investigation of EtAcGE.

  5. Matrix-assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Can Precisely Discriminate the Lineages of Listeria monocytogenes and Species of Listeria.

    PubMed

    Ojima-Kato, Teruyo; Yamamoto, Naomi; Takahashi, Hajime; Tamura, Hiroto

    2016-01-01

    The genetic lineages of Listeria monocytogenes and other species of the genus Listeria are correlated with pathogenesis in humans. Although matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has become a prevailing tool for rapid and reliable microbial identification, the precise discrimination of Listeria species and lineages remains a crucial issue in clinical settings and for food safety. In this study, we constructed an accurate and reliable MS database to discriminate the lineages of L. monocytogenes and the species of Listeria (L. monocytogenes, L. innocua, L. welshimeri, L. seeligeri, L. ivanovii, L. grayi, and L. rocourtiae) based on the S10-spc-alpha operon gene encoded ribosomal protein mass spectrum (S10-GERMS) proteotyping method, which relies on both genetic information (genomics) and observed MS peaks in MALDI-TOF MS (proteomics). The specific set of eight biomarkers (ribosomal proteins L24, L6, L18, L15, S11, S9, L31 type B, and S16) yielded characteristic MS patterns for the lineages of L. monocytogenes and the different species of Listeria, and led to the construction of a MS database that was successful in discriminating between these organisms in MALDI-TOF MS fingerprinting analysis followed by advanced proteotyping software Strain Solution analysis. We also confirmed the constructed database on the proteotyping software Strain Solution by using 23 Listeria strains collected from natural sources. PMID:27442502

  6. Quadrupole time-of-flight mass spectrometry analysis of glycerophospholipid molecular species in the two halophyte seed oils: Eryngium maritimum and Cakile maritima.

    PubMed

    Zitouni, Manel; Wewer, Vera; Dörmann, Peter; Abdelly, Chedly; Ben Youssef, Nabil

    2016-12-15

    Future applications of lipids in clinical cohort studies demand detailed glycerophospholipid molecule information and the application of high-throughput lipidomics platforms. In the present work, a novel sensitive technique with high mass resolution and accuracy was applied to accomplish phospholipid analysis. Nanospray ionization quadrupole time-of-flight mass spectrometry was used to separate and quantify the glycerophospholipid classes as well as molecular species in two halophyte seed oils from Cakile maritima and Eryngium maritimum. Precursor or neutral loss scans of their polar head groups allowed the detection of molecular species within particular glycerophospholipid classes. Phosphatidylcholine was found to be the most abundant glycerophospholipid in both seed oils whereas phosphatidylethanolamine and phosphatidic acid were less abundant. Phosphatidylinositol, phosphatidylserine and phosphatidylglycerol were minor glycerophospholipids. Several molecular species within each class were detected and the main molecular species (C36:4, C36:3, C36:2, 34:2 and C34:1) were quantitatively different between the two halophytes and the different glycerophospholipids. PMID:27451187

  7. Identification of medically relevant species of arthroconidial yeasts by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

    PubMed

    Kolecka, Anna; Khayhan, Kantarawee; Groenewald, Marizeth; Theelen, Bart; Arabatzis, Michael; Velegraki, Aristea; Kostrzewa, Markus; Mares, Mihai; Taj-Aldeen, Saad J; Boekhout, Teun

    2013-08-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used for an extensive identification study of arthroconidial yeasts, using 85 reference strains from the CBS-KNAW yeast collection and 134 clinical isolates collected from medical centers in Qatar, Greece, and Romania. The test set included 72 strains of ascomycetous yeasts (Galactomyces, Geotrichum, Saprochaete, and Magnusiomyces spp.) and 147 strains of basidiomycetous yeasts (Trichosporon and Guehomyces spp.). With minimal preparation time, MALDI-TOF MS proved to be an excellent diagnostic tool that provided reliable identification of most (98%) of the tested strains to the species level, with good discriminatory power. The majority of strains were correctly identified at the species level with good scores (>2.0) and seven of the tested strains with log score values between 1.7 and 2.0. The MALDI-TOF MS results obtained were consistent with validated internal transcribed spacer (ITS) and/or large subunit (LSU) ribosomal DNA sequencing results. Expanding the mass spectrum database by increasing the number of reference strains for closely related species, including those of nonclinical origin, should enhance the usefulness of MALDI-TOF MS-based diagnostic analysis of these arthroconidial fungi in medical and other laboratories.

  8. Global chemical profiling based quality evaluation approach of rhubarb using ultra performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry.

    PubMed

    Zhang, Li; Liu, Haiyu; Qin, Lingling; Zhang, Zhixin; Wang, Qing; Zhang, Qingqing; Lu, Zhiwei; Wei, Shengli; Gao, Xiaoyan; Tu, Pengfei

    2015-02-01

    A global chemical profiling based quality evaluation approach using ultra performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry was developed for the quality evaluation of three rhubarb species, including Rheum palmatum L., Rheum tanguticum Maxim. ex Balf., and Rheum officinale Baill. Considering that comprehensive detection of chemical components is crucial for the global profile, a systemic column performance evaluation method was developed. Based on this, a Cortecs column was used to acquire the chemical profile, and Chempattern software was employed to conduct similarity evaluation and hierarchical cluster analysis. The results showed R. tanguticum could be differentiated from R. palmatum and R. officinale at the similarity value 0.65, but R. palmatum and R. officinale could not be distinguished effectively. Therefore, a common pattern based on three rhubarb species was developed to conduct the quality evaluation, and the similarity value 0.50 was set as an appropriate threshold to control the quality of rhubarb. A total of 88 common peaks were identified by their accurate mass and fragmentation, and partially verified by reference standards. Through the verification, the newly developed method could be successfully used for evaluating the holistic quality of rhubarb. It would provide a reference for the quality control of other herbal medicines.

  9. Characterization by high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry of the lipid fraction of Spirulina platensis pressurized ethanol extract.

    PubMed

    Herrero, Miguel; Vicente, María J; Cifuentes, Alejandro; Ibáñez, Elena

    2007-01-01

    Microalgae have been suggested as a potential source for new functional ingredients, making possible the development of new functional foods from natural origin. Among the natural ingredients, polyunsaturated fatty acids (PUFAs) have generally been identified as an interesting group of compounds with biological activity, mainly related to their anti-inflammatory properties. In this regard, the use of environmentally friendly extraction procedures (e.g. pressurized liquid extraction, PLE) to obtain such natural ingredients is also becoming necessary. In this work, an exhaustive characterization of the lipid fraction of a pressurized ethanolic extract of the microalga Spirulina platensis is carried out. To achieve this objective high-performance liquid chromatography (HPLC) coupled to quadrupole time-of-flight mass spectrometry (QTOF-MS) is employed. The use of the QTOF analyzer allows the selection and isolation of precursor ions as well as providing the high efficiency, sensitivity and mass accuracy required. By means of this powerful hyphenated technique, it was possible to identify several polar lipids in an extract of S. platensis (some of them, to our knowledge, described for the first time in this work), including four free fatty acids, four monogalactosyl monoacylglycerols, three phosphatidylglycerols and two sulfoquinovosyl diacylglycerols.

  10. Detection of bacteria from biological mixtures using immunomagnetic separation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

    USGS Publications Warehouse

    Madonna, A.J.; Basile, F.; Furlong, E.; Voorhees, K.J.

    2001-01-01

    A rapid method for identifying specific bacteria from complex biological mixtures using immunomagnetic separation coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been developed. The technique employs commercially available magnetic beads coated with polycolonal antibodies raised against specific bacteria and whole cell analysis by MALDI-MS. A suspension of a bacterial mixture is mixed with the immunomagnetic beads specific for the target microorganism. After a short incubation period (20 mins) the bacteria captured by the beads are washed, resuspended in deionized H2O and directly applied onto a MALDI probe. Liquid suspensions containing bacterial mixtures can be screened within 1 h total analysis time. Positive tests result in the production of a fingerprint mass spectrum p