Time-of-Flight mass spectrometry

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Untersuchungen zur Anwendbarkeit der "Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry" - Technik für die Identifikation von klinisch relevanten, coryneformen Bakterien

Untersuchungen zur Anwendbarkeit der "Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry" - Technik für die Identifikation von klinisch relevanten, coryneformen Bakterien

desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) System der Firma Bruker Daltonik, Bremen, unter Anwendung einer direkten Bakterienschmier- präparation eine verlässliche Speziesidentifikation coryneformer Bakterien in der mikrobiologischen Routinediagnostik möglich ist. Hierfür wurden im ersten Teil dieser Arbeit 965 Bakterienstämme (11 Gattungen / 53 Bakterienspezies / 4 Subspezies) der Stammsammlung coryneformer Bakterien von Prof. Dr. med. G. Funke, MVZ Labor Dr. Gärtner & Kollegen, Ravensburg, mit MALDI-TOF MS getestet. Hierbei zeigten sich 83,6% richtige Speziesidentifikationen (Score-Wert > 1,7), 90,5% richtige Gattungs- identifikationen (Score-Wert > 1,7), 7,4% falsche Speziesidentifikationen, 0,7% falsche Gattungsidentifikationen und 8,8% nicht verlässliche Identifikationen (Score-Wert < 1,7). Im zweiten Teil der Arbeit wurde gezeigt, dass weder die Wahl des Nährbodens (Columbia 5% Blutagar, CNA (Colistin-Nalidixinsäure)-Blutagar und Schokoladenagar) noch die Vorbehandlung des Bakterienschmierpräparates mit 70%iger Ameisensäure einen signifikanten Einfluss (α=0,05) auf das MALDI-TOF MS Testergebnis haben.
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Rapid and comprehensive evaluation of microalgal fatty acids via untargeted gas chromatography and time-of-flight mass spectrometry

Rapid and comprehensive evaluation of microalgal fatty acids via untargeted gas chromatography and time-of-flight mass spectrometry

Due to their high triacylglyceride content, microalgae are intensively investigated for bio-economy and food applications. However, lipid analysis is a laborious task incorporating extraction, transesterification and typically gas chromatographic mea- surement. Co-elution induces a significant risk of fatty acid misidentification and thus, additional purification steps like thin layer chromatography are needed. Con- trary to database matching approaches, solely targeted analysis is facilitated as com- pound identification is driven by matching retention times or indices with standard substances. In this context, a rapid workflow for the analysis of algal fatty acids is presented. In-situ transesterification was used to simplify sample preparation and conditions were optimized towards fast processing. If results are needed at the very day of sampling, direct processing without a preceding drying step is feasible to obtain a rough estimate about the occurrence of the major compounds. Coupling gas chromatography and time-of-flight mass spectrometry enables untargeted analysis. Unknown compounds may be identified by structural reconstruction of their respec- tive fragmentation patterns and by database matching to routinely avoid mismatches by co-elution of disturbing agents. The developed workflow was successfully applied to derive the exact stereochemistry of all fatty acids from Chlorella vulgaris and a systematic shift depending on physiological state of the cells was confirmed.
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Novel quadrupole time-of-flight mass spectrometry for shotgun proteomics

Novel quadrupole time-of-flight mass spectrometry for shotgun proteomics

Recent advances in proteomic technologies have made MS-based proteomics a central research tool. However, truly complete proteomes are still elusive, mainly due to the high complexity and dynamic range of biological samples with their range of post-translational modifications. More than 10,000 proteins are typically present in each biological sample at one specific condition and after digestion the complexity of analytes increases by at least one order of magnitude, because each protein generates tens to hundreds of peptides. The tremendous challenge of the dynamic range is best illustrated by plasma where protein concentration differs by more than 10 orders of magnitude, i.e. between albumin and low level cytokines [17], while LC-MS typically covers a dynamic range of 4-6 orders of magnitude [29]. Moreover in blood plasma the 22 most abundant proteins constitute about 99% of the total protein mass. Depletion of the high abundant proteins, fractionation techniques and enrichment approaches that target a specific sub-proteome (e.g. phosphopeptides) together with improvements in high resolution liquid phase separations and MS technologies have made it possible to cover the proteome in greater dynamic range and depth, but often introduce their own challenges. For instance, while extensive fractionation of a sample reduces complexity and results in a better proteome coverage [42], it also requires more measurement time, which reduces throughput. Besides reducing the complexity of the biological sample by fractionation or enrichment, high resolution in on-line LC separation helps to address these challenges. Very high pressure, long columns (50 cm) with small porous particles (<75 µg) and long gradients have improved the number of identifiable proteins even in single runs without any depletion or fractionation [111-113]. However, these developments still do not allow complete proteome characterization, and a premise of this thesis is that this could be achieved by a different approach – essential the introduction of third dimension of separation in a compact and efficient way (see below). In the following, the challenges of shotgun proteomics that could be addressed by such a novel approach are described.
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Measurements of exotic calcium isotopes by multi-reflection time-of-flight mass spectrometry and further developments and applications

Measurements of exotic calcium isotopes by multi-reflection time-of-flight mass spectrometry and further developments and applications

In general, there are practical limitations to the minimal bunch width as well as to the length of the drift section. To overcome the latter, Wollnik and Przewloka suggested in the early 1990s to increase the effective drift length by re flecting the ions back and forth between ion-optical mirrors [ 13 ], see figure 1 . The resulting ‘multi-reflection time-of-flight mass spectrometers ’ can store ions on stable trajectories, while losses are mostly determined by ion-neutral collisions, i.e. only depend on the residual gas pressure. This opens the possibility to extend the flight time t to tens of milliseconds and beyond. For typical bunch widths Δt of tens of nanose- conds, mass resolving powers of above R = 100 000 have been achieved, increasing the performance of ToF devices by several orders of magnitude while keeping the apparatus compact. Over the years, this scheme has been further developed in particular by Wollnik et al. [ 14 , 15 ] and Ver- entchikov et al [ 16 , 17 ]. The MR-ToF method found appli- cations in nuclear physics, and such devices are developed or used not only at ISOLTAP but also in Gießen, Germany
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Gas-phase kinetic study of soot precursors with  variable hydrogen contents using a shock tube with  high-repetition-rate time-of-flight mass spectrometry

Gas-phase kinetic study of soot precursors with variable hydrogen contents using a shock tube with high-repetition-rate time-of-flight mass spectrometry

Shock tubes are widely used to study the kinetics of ultra-fast gas-phase reaction at high temperatures [39-43]. The importance of shock tubes for combustion studies is evident from some several studies where large amounts of data were drawn by using a variety of diagnos- tics methods [44-46]. The instantaneous and homogeneous heat-up of the test gas through gas-dynamic effects within a time of 1 μs in shock tubes enables the investigation of fast gas- phase kinetics without influences of transport processes. The uniform temperature distribu- tion and the homogeneous mixture together permit a rigorous decoupling of the physical (e.g., diffusion) and chemical processes (kinetics) within the timescale of the experiment. The shock tube offers the typical condition of temperature ranging from 600 to 4000 K and the pressure ranging from 0.1 to 1000 bar. These properties have proven and established shock tubes as versatile tools to study chemical processes under combustion conditions. In general, shock tubes are thick-walled tubes made of stainless steel with circular, square or rectangular cross sections with a very smooth inner surface [47]. A diaphragm, normally from aluminum, separates the low-pressure part of the shock tube from the high-pressure section. The low-pressure part is referred to as the driven section, which is filled with the test-gas mixture including precursor and is subjected to the shock wave. The high-pressure part of the shock tube is called driver section and is filled with the driver gas. The driver gas is always chosen to have low heat capacity ratios (  ) and high speed of sound. For these rea- sons, a low-molecular-weight gas such as H 2 or He is most frequently used as a driver gas.
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Enhanced analysis of stratified climate archives through upgrade of Laser Ablation Inductively Coupled Plasma Quadrupole to Time of Flight Mass Spectrometry?

Enhanced analysis of stratified climate archives through upgrade of Laser Ablation Inductively Coupled Plasma Quadrupole to Time of Flight Mass Spectrometry?

Solid state lasers are the most common systems used for LA of solid samples. The first LA system developed for ICP instrumentation was a ruby laser, operating at 694 nm (Gray, 1985). However, this system showed poor stability, low power density and large beam diameter. Solid state lasers using a neodymium-doped yttrium aluminium garnet (Nd:YAG) are commercially distributed since the late 1980s. The Nd:YAG laser system operates at 1064 nm wavelength. This infrared (IR) laser shows complex ablation processes, poor precision, and because of poor laser coupling this wavelength is not suitable for many solid materials (Durrant, 1999). Therefore systems were developed using optical components to double (532 nm), triple (355 nm), quadruple (266 nm) and quintuple (216 nm) the frequency; the ablation efficiency increased (Jeffries et al., 1995; Shuttleworth, 1995). Further, high quality optics enables a homogeneous beam profile providing high energy density to couple with the sample matrix. Moreover, Guillong et al. (2003) demonstrated that the usage of a shorter wavelength results in mainly small particles; smaller particles are more efficient converted into ions within the ICP. These wavelengths are used e.g. to determine the partitioning of trace elements in mafic minerals (Foley et al., 1996), the analysis of tree rings that reflect the exposure of trees to metal deposition (Watmough et al., 1997) or for the analysis of archaeological materials (Gratuze et al., 2001).
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Application of Thermal Analysis: Single Photon Ionization Time-of-Flight Mass Spectrometry for Studies of Inorganic Clusters and Ionic Liquids

Application of Thermal Analysis: Single Photon Ionization Time-of-Flight Mass Spectrometry for Studies of Inorganic Clusters and Ionic Liquids

A generally known example for the application of ILs as high-temperature reaction media is the BASIL process developed and operated by BASF. The use of 1-methylimidazole as an acid scavenger and nucleophilic catalyst increased the productivity of the alkoxyphenylphosphine formation process by a factor of 80000. The reaction temperature is approx. 80 °C, the plant went on stream in Q3/2004 at BASF´s Ludwigshafen site [60]. Degussa also presented an ionic liquid based process for the synthesis of organosilicon compounds. The use of an ionic liquid solvent enabled the catalyst to be easily recycled and reused without further treatment after separation form the product at the end of the reaction; reaction temperature was 90 °C [89]. Jiménez et al. tested 1-methyl-3-octylimidazolium tetrafluoroborate and 1-methyl-3-hexylim- idazolium hexafluorophosphate for high-temperature steel lubrication up to 300 °C [90]. Philips et al. tested 1-n-ethyl-3-methylimidazolium tetrafluoroborate, 1,2-di-methyl-3-bu- tylimidazolium bis(trifluoromethylsulfonyl)imide, and 1,2-di-methyl-3-butylimidazolium hex- afluorophosphate as high-temperature lubricants also until 300 °C. They concluded that ILs have a great promise as lubricants up to moderate temperatures because the investigated ILs broke down at higher temperatures in reaction with the iron/steel surface to form several reaction products (mainly FeF 2 ) [91]. Polyethylene glycol functionalized dicationic ionic liquids
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Erwinia species identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry

Erwinia species identification using matrix-assisted laser desorption ionization-time of flight mass spectrometry

Erwinia (Winslow et al., 1920) is a genus of the Entero- bacteriaceae family that was originally created to unite all Gram-negative, nonsporulating, fermentative, peritri- chously flagellated plant-pathogenic bacteria (Kwon et al., 1997). Since its inception, the genus has undergone sev- eral taxonomical rearrangements following refined phe- notypic characterization or DNA sequence analysis, with many species being transferred to other genera such as Pectobacterium (Hauben et al., 1998), Dickeya (Samson et al., 2005) (both genera containing phytopathogenic pecti- nolytic bacteria causing soft rot diseases), Pantoea (Brady et al., 2010), Brenneria (Hauben et al., 1998), Lonsdalea (Brady et al., 2012), or Enterobacter (Brenner et al., 1986; Dickey and Zumoff, 1988). In addition, a number of new species were recently described and approved within the genus including Erwinia piriflorinigrans (López et al., 2011) and Erwinia uzenensis (Matsuura et al., 2012), two novel pathogens that affects European pear trees; Erwinia ty- pographica, isolated from the gut of healthy bark beetles (Skrodenyt ė -Arba č iauskien ė et al., 2012); Erwinia gerun- densis a cosmopolitan epiphyte originally isolated from pome fruit trees (Rezzonico et al., 2016); and “Candida- tus Erwinia dacicola”, an olive fly endosymbiont (Estes et al., 2009). As of January 2017, 19 species are listed in the genus.
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Anwendbarkeit der Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) für den Nachweis und die Differenzierung von Leptospira spp. im Vergleich zum Multilocus Sequence Typing (MLST)

Anwendbarkeit der Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) für den Nachweis und die Differenzierung von Leptospira spp. im Vergleich zum Multilocus Sequence Typing (MLST)

The family Leptospiraceae consists of a wide variety of genetic and antigenic diverse leptospiral serovars and strains. Representatives of the pathogenic genomospecies are known to have a zoonotic potential and are important pathogens in human and veterinary medicine. Detection of the pathogen is still complicated due to the complex pathogeneses of the disease and the wide diversity of leptospiral strains. Even though it is known that big varieties of the test results occur, the microscopic agglutination test (MAT) is still said to be the gold standard in routine diagnostics. Interpretation of the MAT test is complicated since regional differences and the epidemiological situation do have an impact on the test result. Despite the MAT-based, serological classification scheme a second genetic classification system, exists in which leptospiral serovars are classified into different genomospecies according to their genetic diversity. Based on the sequencing of the 16S rRNA the genomospecies can further be assigned to pathogenic, non-pathogenic and intermediate species. 16S rRNA sequencing is considered to be the gold standard for the taxonomic classification of bacteria. MALDI-TOF MS analysis can be compared to this genetic classification scheme as this technology comprises variations of the amino acid sequences of the detected housekeeping genes on protein level. These housekeeping genes mainly encode for ribosomal proteins and some structural proteins. MALDI-TOF MS detects and compares the protein spectra that are specific for each bacteria species. Using this technology, clinical isolates can be identified to genus- species- or strain level. Furthermore, the taxonomic classification of bacteria using MALDI-TOF MS can be compared to the 16S rRNA sequencing.
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Further developments of multi-reflection time-of-flight mass spectrometry and first application for cluster research

Further developments of multi-reflection time-of-flight mass spectrometry and first application for cluster research

2 The multi-reflection time-of-flight mass spectrometer A multi-reflection time-of-flight mass spectrometer, as shown in Fig. 2.1, aims to repeatedly use a part of the ions’ flight path by reflecting them through the same field- free drift section. The resulting elongated flight times make MR-ToF devices excellent high-resolution mass spectrometers that can reach mass resolving powers R beyond 100 000 in just a few tens of milliseconds [27–30]. For the required axial ion confinement, the maximum of the electrostatic mirror potentials must exceed the ions’ total energy (Fig. 2.2). Ion injection and ejection can be performed by switching off the corresponding mirror potential for a short time and allowing ion bunches to pass. Alternatively, an “in-trap lift” can be used to lower and raise the ion energy between the mirrors, as was first introduced at the ISOLTRAP MR-ToF mass spectrometer at ISOLDE/CERN [31]. By switching a voltage applied to the device’s central drift tube while ions are inside of it, their energy can be adjusted without disturbance (Faraday-cage principle). The principal gain from this type of operation lies in the fact that the ion energy during storage is decoupled from the transfer energy outside of the analyzer. This significantly reduces the experimental complexity of adjusting either one and is especially useful for tuning the MR-ToF temporal focus (see next section): the gradient of the mirror potentials that is experienced by stored ions can be changed by adjusting only a single voltage. Another advantage of the in-trap lift is an increased mirror-voltage stability. Since all of the reflecting potentials are entirely static, flight-time fluctuations arising from switching noise and ringing are eliminated.
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Present and future isochronous mass spectrometry at GSI-FAIR : 25 new masses of fission fragments ; novel analysis method ; design of a new Time-of-Flight detector system

Present and future isochronous mass spectrometry at GSI-FAIR : 25 new masses of fission fragments ; novel analysis method ; design of a new Time-of-Flight detector system

The origin of modern nuclear physics was the discovery of radioactivity by Henri Becquerel and experiments by Pierre and Marie Curie. Their work was honoured with the Nobel Prize in physics in 1903 [ Nob14 ]. In the following years many im- portant experiments were performed to establish a new and better understanding of the atomic structure. In 1909 Ernest Rutherford and his students Hans Geiger and Ernest Marsden performed the famous scattering experiment with α-particles on a gold foil that completely changed the understanding of the atoms [ GM09 ]. Rutherford concluded from the results that almost the complete mass and the positive charge of the ions have to be concentrated in its tiny centre, the nucleus. Further experiments with α-particles and hydrogen atoms showed, that the mass of an α-particle is less than 4 times the mass of hydrogen. Arthur Stanley Edding- ton connected this so called ”mass defect” in 1920 [ Edd20 ] to the popular equation by Einstein E = mc 2 and it was believed that it is the source of stellar energy.
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First on-line applications of a multi-reflection time-of-flight mass separator at ISOLTRAP and the mass measurement of 82Zn

First on-line applications of a multi-reflection time-of-flight mass separator at ISOLTRAP and the mass measurement of 82Zn

Injection and ejection of ions from MR-ToF MS has been achieved by switching the electric potentials of the entrance and exit mirrors, respectively, to appropriate lower values while the ions are passing. In the following, an alternative method is pre- sented that simplifies the ion transfer to and from the MR-ToF MS considerably: instead of lowering a sufficient number of mir- ror electrodes, a single capture pulse is applied to just one drift tube between the ion mirrors. In addition, by varying the height of this voltage pulse applied to the in-trap drift tube, the ions’ time focus can be adjusted with respect to the distance from the trapping region. Thus, by use of appropriate settings the resolving power for mass spectrometry or for the separation of particular ions of inter- est from contaminant species can be maximized. Furthermore, by use of the new in-trap potential-lift technique the trapping energy inside the MR-ToF device becomes independent of the transfer energy in the up-/downstream beamline. This decoupling of the MR-ToF MS from the beamline has several advantages, in partic- ular with respect to their individual optimizations. Moreover, it is not necessary that injection and ejection pulses are of equal height which gives the possibility to change the kinetic energy after the MR-ToF device. In the following these features will be discussed in detail.
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Developing mass spectrometry towards applications in clinical proteomics

Developing mass spectrometry towards applications in clinical proteomics

Global mapping and localization of post-translational modifications (PTMs) such as phosphorylation is crucial for understanding the activity of the cell. Phosphorylation acts as a molecular switch in various signaling pathways and plays a pivotal role in many biological processes 1 . Mass spectrometry (MS)-based proteomics has emerged as a powerful technique for studying PTMs 2-4 . Among many different versions of MS-based phosphoproteomics, hybrid instruments with quadrupole and time of flight analyzers (quadrupole – TOF) or with two different types of ion traps have gained popularity in the last decade 5 . In particular, the combination of high mass accuracy for the precursor ion and low mass accuracy for the fragment ions from linear ion trap – Orbitrap instruments (LTQ-Orbitrap) is a widely applied instrumental configuration. Employing this ‘high-low’ strategy in large scale phosphoproteomic approaches has led to the identification and quantification of several thousand phosphosites in single projects 6-8 . However, analyzing phosphopeptides by Collision Induced Dissociation (CID) in the ion trap (resonant excitation mediated collision) results in significant neutral loss for phospho- serine (pS) and phospho-threonine (pT) containing peptides and this can require multiple activation steps to efficiently fragment them 9, 10 . Furthermore, in ion trap fragmentation the ‘one third rule’ (loss of low mass ions depending on the fragmentation q value) 11 precludes the analysis of low molecular weight reporter ions that are very informative for example in the case of phospho-tyrosine (pY) ions 12, 13 . A different class of fragmentation techniques, electron capture dissociation (ECD) 14 or electron transfer dissociation (ETD) 15 , complements CID, particularly for labile phosphopeptides 16 .
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Characterization of Yersinia using MALDI-TOF mass spectrometry and chemometrics.

Characterization of Yersinia using MALDI-TOF mass spectrometry and chemometrics.

enterocolitica, Yersinia pseudotuberculosis, and Yersinia pestis, are pathogenic in humans. Rapid and accurate identification of Yersinia strains is essential for appropriate therapeutic management and timely intervention for infection control. In the past decade matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) in combination with computer-aided pattern recognition has evolved as a rapid, objective, and reliable technique for microbial identification. In this comprehensive study a total of 146 strains of all currently known Yersinia species complemented by 35 strains of other relevant genera of the Enterobacteriaceae family were investigated by MALDI-TOF MS and chemometrics. Bacterial sample preparation included microbial inactivation according to a recently developed mass spectrometry compatible inactivation protocol. The mass spectral profiles were evaluated by supervised feature selection methods to identify family-, genus-, and species- specific biomarker proteins and—for classification purposes—by pattern recognition techniques. Unsupervised hierarchical cluster analysis revealed a high degree of correlation between bacterial taxonomy and subproteome-based MALDI-TOF MS classification. Furthermore, classification analysis by supervised artificial neural networks allowed identification of strains of Y. pestis with an accuracy of 100%. In-depth analysis of proteomic data demonstrated the existence of Yersinia-specific biomarkers at m/z 4350 and 6046. In addition, we could also identify species-specific biomarkers of Y.
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Some Remarks About Laser-Induced Mass Spectrometry of Bacteria 

Some Remarks About Laser-Induced Mass Spectrometry of Bacteria 

Laser-induced mass spectrom etry The LAM M A 500 instrum ent used for the experi­ m ents is a powerful tool in microanalysis [17]. In this instrum ent the m aterial to be analysed is vaporized and partly ionized in the laser focus by a single ultra- short laser pulse (irradiance: 10l(l—1011 W x cm "2). The samples used must be stable in a high vacuum state and if layers or tissues are to be m easured they must be perforable with a single laser pulse. A light microscope and an x-y-m anipulator give the oppor­ tunity to choose the part of the sample to be anal­ ysed. The frequency quadrupled Q -sw itched-N d; Y A G laser emits light with a wave-length of 265 nm. Laser-induced ionform ation produces ions of both positive and negative charge. As a result, depending on the polarities of electric potentials, a time of flight spectrum of either positive or negative ions is obtained by a single laser shot.
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Gutenberg Open Science: Application of time-of-flight aerosol mass spectrometry for the real-time measurement of particle-phase organic peroxides: an online redox derivatization–aerosol mass spectrometer (ORD-AMS)

Gutenberg Open Science: Application of time-of-flight aerosol mass spectrometry for the real-time measurement of particle-phase organic peroxides: an online redox derivatization–aerosol mass spectrometer (ORD-AMS)

For the proof-of-principle studies with SOA, a laboratory- scale reaction chamber in continuous-flow tank reactor mode was used. Synthetic air was supplied with a total flow of 7.6 L min −1 into the 100 L chamber, resulting in a residence time of 13.5 min. The total flow was composed of a gas stream through a diffusion test gas source (Thorenz et al., 2012) (0.600 L min −1 ), where the VOC of interest was added to the synthetic air supply. A second gas stream (2.6 L min −1 ) was humidified using a gas-washing bottle, and a third gas flow was led through an ozone generator (Dasibi Environ- mental Corp. Model 1008 RS O3 analyzer, Glendale, CA, USA; 2.7 L min −1 ). To add seed particles an aqueous solu- tion of ammonium sulfate (ca. 0.5 g L −1 ; > 99.5 %, Merck KGaA, Darmstadt, Germany) was nebulized using techni- cal nitrogen and introduced into the chamber (1.7 L min −1 ). Temperature and relative humidity were 25 ◦ C and 61 % for the α-pinene ozonolysis and 22 ◦ C and 59 % for the β-pinene ozonolysis. They were monitored by a thermo-hygrometer (Amarell, ama-digit ad 910 h, Kreuzwertheim, Germany). The chamber was set to be under slight overpressure to pre- vent the entry of laboratory air into the setup. The reaction chamber was wrapped with aluminum foil to avoid photo- chemical reactions. For the ozonolysis of α-pinene (99 %, Fluka, Seelze, Germany), the chamber was first equilibrated with the terpene before the ozone generator was switched on. For the β-pinene (99 %, Sigma Aldrich Chemie GmbH, Steinheim, Germany) experiments, the order of the addition of the individual compounds was reversed – i.e., ozone was added before the terpene. The ozone concentration was es- timated to be about 1 ppm, while the α-pinene concentra- tion was set to 290 ppbv and the β-pinene concentration to 380 ppbv. To remove gaseous organic compounds, the SOA formed in the reaction chamber was led through two diffu- sion denuders filled with activated charcoal.
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Further development and application of a mobile multiple-reflection time-of-flight mass spectrometer for analytical high-resolution tandem mass spectrometry

Further development and application of a mobile multiple-reflection time-of-flight mass spectrometer for analytical high-resolution tandem mass spectrometry

The mass spectrometric analysis of complex volatile and nonvolatile crude oil components falls into the category of such experiments and is one of the most challenging fields in mass spectrometry [Panda et al., 2007]. Crude oil samples are extremely complex and can contain several ten thousand different components. Mass measurements yield dense mass spectra and tens of isobaric constituents at each mass unit. Thus, it is difficult to determine the exact chemical composition of the sample and the use of highly accurate mass spectrometers is vital. If one is interested in the chemical structure of a certain ion species the task becomes even more difficult, since conventional tandem mass spectrometers do not allow for the isolation of molecules from their nearby isobaric contaminants. Hence, fragment spectra always contain product ions of many ion species, which makes the determination of chemical structures very challenging or even impossible. In the following, results of a crude oil measurement with the MR-TOF-MS are presented. The sample was provided by the Max Planck Institute for Coal Re-
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Identification of Adult Fasciola spp. Using Matrix-Assisted Laser/Desorption Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry

Identification of Adult Fasciola spp. Using Matrix-Assisted Laser/Desorption Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry

Interestingly, while creating the MSPs for the in-house database, it was observed that two out of seven F. gigantica samples used (i.e., isolates no. FGN23 and FGN24) clustered together in a group with slightly different spectral patterns than the other five F. gigantica samples. Such observed intra-species differences in the mass spectra profiles could be explained by a minor genetic variation (e.g., a non-synonymous mutation, which could affect the protein profile). In this context, it is important to mention that several studies have reported the existence of an intermediate “hybrid” species of Fasciola, which can only be discriminated by specific molecular methods [ 34 ]. Liu and colleagues [ 35 ] studied the sequence data of protein-encoding genes and showed that the intermediate form of Fasciola is more closely related to F. gigantica than F. hepatica. Similar studies from sub-Saharan Africa have suggested that the epidemiology of fascioliasis in this part of the world may be more complex than previously thought, and that F. gigantica is not the only species occurring [ 36 ]. “Hybrid” Fasciola spp. have also been reported from Chad [ 37 ], and these might also occur in Nigeria, where the F. gigantica samples for the current MALDI-TOF MS were obtained. Since “hybrid” species cannot be accurately identified by amplification of the COX1 as performed here, further molecular investigations pertaining to the genomics (e.g., sequencing of the internal transcribed spacer (ITS) region as reported by Evack and colleagues [ 37 ]) of these samples will be interesting. Indeed, while we aligned and comparatively analyzed the obtained COX1 sequences, we were unable to identify specific variable sites, which would have allowed to accurately identify “hybrid” isolates.
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A multi-reflection time-of-flight mass spectrometer for cluster research and methodological developments with clusters

A multi-reflection time-of-flight mass spectrometer for cluster research and methodological developments with clusters

This decision was made, because for the investigation of stored particles, MR-ToF analyz- ers, aside from high mass-rasolcing powers, come with advantages known from other ToF applications, such as virtually unrestricted mass ranges and fast processing times. Ad- ditionally, they offer an open geometry and easy setup without any need for magnetic or radio-frequency fields. As already mentioned, particles are confined by mirror-electrode potentials that exceed the total energy of the particles. As a side note it is mentioned, that in contrast to Paul- and Penning traps, particles need a sufficient energy to be trapped at all, because otherwise they would violate earnshaw’s theorem. If particles of different masses, or more correctly different mass-to-charge ratios m/q, are stored they are in general already spatially separated during the capture pulse, because of their cor- respondingly different velocities. This spatial separation increases with flight time and each reflection and thus the resolving power increases with the total time of flight. Par- ticles of the same m/q have an energy distribution from their acceleration, which needs to be compensated to avoid a spatially diverging ion bunch. To this end, the potential of the mirror electrodes is adjusted to match the revolution time of particles with the same m/q, but different kinetic energies. This adjustment is achieved by allowing particles with higher energies to penetrate deeper into the mirror stack and, thus, leading to a longer path for faster particles. The remaining, uncompensated spatial distribution is the initial one with the addition of higher order aberrations. Higher order aberrations are accumulated inside and outside the analyzer, they increase the spread of the ion bunch with increasing storage times and, thus, limit the resolving power. According to this discussion, the mass resolving power is given as [72]
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High Sensitivity in CID Mass Spectrometry, Structure Analysis of Pyrolysis Fragments 

High Sensitivity in CID Mass Spectrometry, Structure Analysis of Pyrolysis Fragments 

The experimental set up as described in the foregoing part allows the structure elucidation of various ions representing a single mass peak in a spectrum and is in particular developed for measure­ ment o f very short-lasting ion pulses, e. g. those obtained on flash pyrolysis (Curie point pyrolysis [9] or laser desorption mass spectrometry [10]). In the following section an example is described to demon­ strate the applicability of the system. It concerns one of the mass peaks in pyrolysis mass spectra of complete bacteria.
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