Sample records for atmospheric-pressure chemical ionization

  1. Analysis of Genetically Modified Canola Varieties by Atmospheric Pressure Chemical Ionization Mass Spectrometric and Flame Ionization Detection

    Microsoft Academic Search

    William C. Byrdwell; William E. Neff

    1996-01-01

    Canola oil triacylglycerols from genetically modified canola lines were conclusively identified by reverse phase HPLC coupled with atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. APCI-MS is a soft ionization technique, which gave simple spectra for triacylglycerols. Spectral identification of the triacylglycerols was based on the diacylglycerol fragments and on the protonated molecular ion [M+H], except trisaturates which gave no

  2. Atmospheric pressure chemical ionization of fluorinated phenols in atmospheric pressure chemical ionization mass spectrometry, tandem mass spectrometry, and ion mobility spectrometry

    NASA Technical Reports Server (NTRS)

    Eiceman, G. A.; Bergloff, J. F.; Rodriguez, J. E.; Munro, W.; Karpas, Z.

    1999-01-01

    Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) for fluorinated phenols (C6H5-xFxOH Where x = 0-5) in nitrogen with Cl- as the reagent ion yielded product ions of M Cl- through ion associations or (M-H)- through proton abstractions. Proton abstraction was controllable by potentials on the orifice and first lens, suggesting that some proton abstraction occurs through collision induced dissociation (CID) in the interface region. This was proven using CID of adduct ions (M Cl-) with Q2 studies where adduct ions were dissociated to Cl- or proton abstracted to (M-H)-. The extent of proton abstraction depended upon ion energy and structure in order of calculated acidities: pentafluorophenol > tetrafluorophenol > trifluorophenol > difluorophenol. Little or no proton abstraction occurred for fluorophenol, phenol, or benzyl alcohol analogs. Ion mobility spectrometry was used to determine if proton abstraction reactions passed through an adduct intermediate with thermalized ions and mobility spectra for all chemicals were obtained from 25 to 200 degrees C. Proton abstraction from M Cl- was not observed at any temperature for phenol, monofluorophenol, or difluorophenol. Mobility spectra for trifluorophenol revealed the kinetic transformations to (M-H)- either from M Cl- or from M2 Cl- directly. Proton abstraction was the predominant reaction for tetra- and penta-fluorophenols. Consequently, the evidence suggests that proton abstraction occurs from an adduct ion where the reaction barrier is reduced with increasing acidity of the O-H bond in C6H5-xFxOH.

  3. Evaluating the Utility of an Atmospheric Pressure Chemical Ionization Mass Spectrometer for Analyzing Organic Peroxides

    NASA Astrophysics Data System (ADS)

    Jameer, A.; Hastie, D. R.

    2013-12-01

    Secondary organic aerosols (SOA) are known to affect the earth's radiation budget through its ability to scatter and absorb radiation. Consequently, the mechanisms and factors that influence SOA composition and formation are poorly understood. However, recent modeling studies coupled with smog chamber experiments suggest that organic peroxides (organic hydroperoxides and peroxyhemiacetals) might be a major component of SOA composition under low NOx conditions. This study utilized an atmospheric pressure chemical ionization mass spectrometer (APCI-MS) in the positive mode to detect organic peroxides. Mass spectra of organic peroxides analyzed in this study show excessive fragmentation during ionization with protonated water clusters. It was believed that intact ions were not found due to decomposition in the ion source. Future work will explore new reagents for ionization to reduce fragmentation during analysis.

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

    PubMed

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

    2012-08-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  6. Atmospheric pressure chemical ionization mass spectrometry of pyridine and isoprene: potential breath exposure and disease biomarkers.

    PubMed

    Kapishon, Vitaliy; Koyanagi, Gregory K; Blagojevic, Voislav; Bohme, Diethard K

    2013-06-01

    Volatile organic compounds (VOCs) in exhaled human breath can serve as potential disease-specific and exposure biomarkers and therefore can reveal information about a subject's health and environment. Pyridine, a VOC marker for exposure to tobacco smoke, and isoprene, a liver disease biomarker, were studied using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). While both molecules could be detected in low-ppb levels, interactions of the ionized analytes with their neutral forms and ambient air led to unusual ion/molecule chemistry. The result was a highly dynamic system and a nonlinear response to changes in analyte concentration. Increased presence of ambient water was found to greatly enhance the detection limit of pyridine and only slightly decrease that of isoprene. APCI-MS is shown to be a promising analytical tool in breath analysis with good detection limits, but its application requires a better understanding of the ion/molecule chemistry that may affect VOC quantification from a chemically complex system such as human breath. PMID:23579200

  7. Laser Microdissection and Atmospheric Pressure Chemical Ionization Mass Spectrometry Coupled for Multimodal Imaging

    SciTech Connect

    Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Kertesz, Vilmos [ORNL; Van Berkel, Gary J [ORNL

    2013-01-01

    This paper describes the coupling of ambient laser ablation surface sampling, accomplished using a laser capture microdissection system, with atmospheric pressure chemical ionization mass spectrometry for high spatial resolution multimodal imaging. A commercial laser capture microdissection system was placed in close proximity to a modified ion source of a mass spectrometer designed to allow for sampling of laser ablated material via a transfer tube directly into the ionization region. Rhodamine 6G dye of red sharpie ink in a laser etched pattern as well as cholesterol and phosphatidylcholine in a cerebellum mouse brain thin tissue section were identified and imaged from full scan mass spectra. A minimal spot diameter of 8 m was achieved using the 10X microscope cutting objective with a lateral oversampling pixel resolution of about 3.7 m. Distinguishing between features approximately 13 m apart in a cerebellum mouse brain thin tissue section was demonstrated in a multimodal fashion including co-registered optical and mass spectral chemical images.

  8. Fundamentals of ambient metastable-induced chemical ionization mass spectrometry and atmospheric pressure ion mobility spectrometry

    NASA Astrophysics Data System (ADS)

    Harris, Glenn A.

    Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions. New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (< 1000 Da) molecules with a wide range of polarities. Although there is a large list of reported applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms. The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in Chapter 1. Chapter 2 presents the first investigations into the atmospheric pressure ion transport phenomena during DART analysis. Chapter 3 provides a comparison on the internal energy deposition processes during DART and pneumatically assisted-ESI. Chapter 4 investigates the complex spatially-dependent sampling sensitivity, dynamic range and ion suppression effects present in most DART experiments. New implementations and applications with DART are shown in Chapters 5 and 6. In Chapter 5, DART is coupled to multiplexed drift tube ion mobility spectrometry as a potential fieldable platform for the detection of toxic industrial chemicals and chemical warfare agents simulants. In Chapter 6, transmission-mode DART is shown to be an effective method for reproducible sampling from materials which allow for gas to flow through it. Also, Chapter 6 provides a description of a MS imaging platform coupling infrared laser ablation and DART-like phenomena. Finally, in Chapter 7 I will provide perspective on the work completed with DART and the tasks and goals that future studies should focus on.

  9. Kinetic and Thermodynamic Control of Protonation in Atmospheric Pressure Chemical Ionization

    NASA Astrophysics Data System (ADS)

    Chai, Yunfeng; Hu, Nan; Pan, Yuanjiang

    2013-07-01

    For p-(dimethylamino)chalcone ( p-DMAC), the N atom is the most basic site in the liquid phase, whereas the O atom possesses the highest proton affinity in the gas phase. A novel and interesting observation is reported that the N- and O-protonated p-DMAC can be competitively produced in atmospheric pressure chemical ionization (APCI) with the change of solvents and ionization conditions. In neat methanol or acetonitrile, the protonation is always under thermodynamic control to form the O-protonated ion. When methanol/water or acetonitrile/water was used as the solvent, the protonation is kinetically controlled to form the N-protonated ion under conditions of relatively high infusion rate and high concentration of water in the mixed solvent. The regioselectivity of protonation of p-DMAC in APCI is probably attributed to the bulky solvent cluster reagent ions (SnH+) and the analyte having different preferred protonation sites in the liquid phase and gas phase.

  10. Stability studies of propoxur herbicide in environmental water samples by liquid chromatography–atmospheric pressure chemical ionization ion-trap mass spectrometry

    Microsoft Academic Search

    Lei Sun; Hian Kee Lee

    2003-01-01

    Liquid chromatography–atmospheric pressure ionization ion-trap mass spectrometry has been investigated for the analysis of polar pesticides in water. The degradation behavior of propoxur, selected as a model pesticide belonging to the N-methylcarbamate group, in various aqueous matrices (Milli-Q water, drinking water, rain water, seawater and river water) was investigated. Two interfaces of atmospheric pressure ionization, atmospheric pressure chemical ionization (APCI)

  11. Analysis of bitter limonoids in citrus juices by atmospheric pressure chemical ionization and electrospray ionization liquid chromatography-mass spectrometry.

    PubMed

    Manners, Gary D; Breksa, Andrew P; Schoch, Thomas K; Hidalgo, Marlene B

    2003-06-18

    Improved analytical techniques for bitter limonoids in citrus and citrus juices can expedite the evaluation of freeze-induced citrus damage for citrus growers and juice quality for citrus juice producers. Microbore normal-phase and reverse-phase chromatography coupled to a mass spectrometer operating in a positive ion atmospheric pressure chemical ionization and electrospray ionization modes were found to be rapid, selective, and sensitive methods for the analysis of the bitter limonoids limonin and nomilin in citrus juices. Analysis was performed on a chloroform extract of citrus juice to which an internal standard was added. The methods are capable of detecting citrus limonoids in citrus juice in the 60-200 picogram range and quantifying citrus juice limonoids in concentrations as low as 120 picograms. An accurate "total limonoid bitterness" in citrus juice, as represented by the combined occurrence of limonin and nomilin, is easily determined by these methods. PMID:12797731

  12. Scanning Diode Laser Desorption Thin-Layer Chromatography Coupled with Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Peng, Song; Ahlmann, Norman; Edler, Michael; Franzke, Joachim

    Continuous wave diode laser is applied for desorption of an analyte from a porous surface of a thin-layer plate covered with a graphite suspension. The thermally desorbed analyte molecules are ionized in the gas phase by a corona discharge at atmospheric pressure. Therefore, both essential processes - the desorption and the ionization of analyte molecules, which are often performed in one step - are separated. Reserpine was chosen as model analyte, which is often used for specification of mass spectrometers. No fragmentation was observed because of efficient collisional cooling under atmospheric pressure. The influence of diode laser power and the composition of the graphite suspension were investigated, and a primary optimization was performed. An interface to allow online qualitative and quantitative full plate detection and analysis of compounds separated by thin-layer chromatography is presented.

  13. Document authentication at molecular levels using desorption atmospheric pressure chemical ionization mass spectrometry imaging.

    PubMed

    Li, Ming; Jia, Bin; Ding, Liying; Hong, Feng; Ouyang, Yongzhong; Chen, Rui; Zhou, Shumin; Chen, Huanwen; Fang, Xiang

    2013-09-01

    Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS), which was operated in either a gasless, solvent-free or methanol vapor-assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI-MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI-MS imaging differentiated a 10-min old from two 4 h old samples. Non-destructive forensic analysis of forged signatures either handwritten or computer-assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI-MS. The experimental results show that DAPCI-MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications. PMID:24078245

  14. Choosing between atmospheric pressure chemical ionization and electrospray ionization interfaces for the HPLC/MS analysis of pesticides

    USGS Publications Warehouse

    Thurman, E.M.; Ferrer, I.; Barcelo, D.

    2001-01-01

    An evaluation of over 75 pesticides by high-performance liquid chromatography/mass spectrometry (HPLC/MS) clearly shows that different classes of pesticides are more sensitive using either atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI). For example, neutral and basic pesticides (phenylureas, triazines) are more sensitive using APCI (especially positive ion). While cationic and anionic herbicides (bipyridylium ions, sulfonic acids) are more sensitive using ESI (especially negative ion). These data are expressed graphically in a figure called an ionization-continuum diagram, which shows that protonation in the gas phase (proton affinity) and polarity in solution, expressed as proton addition or subtraction (pKa), is useful in selecting APCI or ESI. Furthermore, sodium adduct formation commonly occurs using positive ion ESI but not using positive ion APCI, which reflects the different mechanisms of ionization and strengthens the usefulness of the ionization-continuum diagram. The data also show that the concept of "wrong-way around" ESI (the sensitivity of acidic pesticides in an acidic mobile phase) is a useful modification of simple pKa theory for mobile-phase selection. Finally, this finding is used to enhance the chromatographic separation of oxanilic and sulfonic acid herbicides while maintaining good sensitivity in LC/MS using ESI negative.

  15. Qualitative analysis of some carboxylic acids by ion-exclusion chromatography with atmospheric pressure chemical ionization mass spectrometric detection

    Microsoft Academic Search

    Murad I. H. Helaleh; Kazuhiko Tanaka; Hiroshi Taoda; Wenzhi Hu; Kiyoshi Hasebe; Paul R. Haddad

    2002-01-01

    A simple, selective and sensitive method for the determination of carboxylic acids has been developed. A mixture of formic, acetic, propionic, valeric, isovaleric, isobutyric, and isocaproic acids has been separated on a polymethacrylate-based weak acidic cation-exchange resin (TSK gel OA pak-A) based on an ion-exclusion chromatographic mechanism with detection using UV-photodiode array, conductivity and atmospheric pressure chemical ionization mass spectrometry

  16. Production and Utilization of CO3- Produced by a Corona Discharge in Air for Atmospheric Pressure Chemical Ionization

    SciTech Connect

    Ewing, Robert G.; Waltman, Melanie J.

    2010-12-14

    Atmospheric pressure chemical ionization is a multistep ionization process used in mass spectrometry and ion mobility spectrometry. The formation of product ions depends upon interactions with the analyte and the reactant ion species formed in the ionization source. The predominant reactant ion observed in a point-to-plane corona discharge in air occurs at m/z 60. There have been multiple references in the literature to the identity of this ion with some disagreement. It was postulated to be either CO3- or N2O2-. The identity of this ion is important as it is a key to the ionization of analytes. It was determined here to be CO3- through the use of 18O labeled oxygen. Further confirmation was provided through MS/MS studies. The ionization of nitroglycerine (NG) with CO3- produced the adduct NG•CO3-. This was compared to ionization with NO3- and Cl- reactant ions that also formed adducts with NG. The fragmentation patterns of these three adducts provides insight into the charge distribution and indicates that CO3- has a relatively high electron affinity similar to that of nitrate.

  17. Confirmation of avermectin residues in food matrices with negative-ion atmospheric pressure chemical ionization liquid chromatography/mass spectrometry.

    PubMed

    Turnipseed, S B; Roybal, J E; Rupp, H S; Gonzales, S A; Pfenning, A P; Hurlbut, J A

    1999-01-01

    A multi-residue LC/MS method has been developed to confirm avermectin drug residues in several food matrices. Ivermectin (IVR), doramectin (DOR), eprinomectin (EPR) and moxidectin (MOX) are confirmed using atmospheric pressure chemical ionization (APCI) with negative ion detection and selected ion monitoring of three to four ions for each compound. The drug residues are extracted from tissue or milk using previously published procedures. IVR and DOR are confirmed at 20 ppb levels in fortified salmon muscle; IVR is also confirmed in tissue from salmon dosed with the drug. Residues of DOR, IVR, and EPR are confirmed in fortified milk at the 20 ppb level and in fortified beef liver at 40 ppb. Residues of MOX can also be confirmed in these matrices, but at slightly higher levels (40-80 ppb). PMID:10204245

  18. Characterization of phthalides in Ligusticum chuanxiong by liquid chromatographic-atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Zhang, Xiaozhe; Xiao, Hongbin; Xu, Qing; Li, Xiuling; Wang, Jianing; Liang, Xinmiao

    2003-09-01

    High-performance liquid chromatography (HPLC) with diode-array detection interfaced to atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) is applied to analyze phthalides from Chuanxiong (the rhizome of Ligusticum chuanxiong). This herb material, containing plenty of phthalide compositions, is selected as the analytical target in this paper for its hematological activity. Some of the phthalides are not stable and are difficult to analyze by gas chromatography-MS. Under optimized LC-MS-MS conditions, six phthalides in the methanol extract of Chuanxiong are unambiguously identified, and characteristic fragments are obtained using homemade reference standards. Ten other phthalides in the extract are confirmed by means of LC-APCI-MS with positive-negative ion mode and collision-induced dissociation in combination with UV spectrophotometry. The results show that LC-MS-MS is a method of choice for fast detection and detailed structural analysis of such mixtures in the crude extract of Chuanxiong. PMID:14558936

  19. Comparative analysis of different plant oils by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Jakab, Annamaria; Héberger, Károly; Forgács, Esther

    2002-11-01

    Different vegetable oil samples (almond, avocado, corngerm, grapeseed, linseed, olive, peanut, pumpkin seed, soybean, sunflower, walnut, wheatgerm) were analyzed using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. A gradient elution technique was applied using acetone-acetonitrile eluent systems on an ODS column (Purospher, RP-18e, 125 x 4 mm, 5 microm). Identification of triacylglycerols (TAGs) was based on the pseudomolecular ion [M+1]+ and the diacylglycerol fragments. The positional isomers of triacylglycerol were identified from the relative intensities of the [M-RCO2]+ fragments. Linear discriminant analysis (LDA) as a common multivariate mathematical-statistical calculation was successfully used to distinguish the oils based on their TAG composition. LDA showed that 97.6% of the samples were classified correctly. PMID:12462617

  20. No-discharge atmospheric pressure chemical ionization: evaluation and application to the analysis of animal drug residues in complex matrices.

    PubMed

    Turnipseed, Sherri B; Andersen, Wendy C; Karbiwnyk, Christine M; Roybal, José E; Miller, Keith E

    2006-01-01

    Alternative ionization methods are increasingly being utilized to increase the versatility and selectivity of liquid chromatography/mass spectrometry (LC/MS). One such technique is the practice of using commercially available atmospheric pressure chemical ionization (APCI) sources with the corona discharge turned off, a process termed no-discharge APCI (ND-APCI). The relative LC/MS responses for several different classes of veterinary drugs were obtained by using ND-APCI, electrospray ionization (ESI), and APCI. While the ND-APCI-MS and -MSn spectra for these compounds were comparable with ESI, ND-APCI provided advantages in sensitivity and selectivity for some compounds. Drugs that were charged in solution as cations or sodium adducts responded particularly well with this technique. Instrumental parameters such as temperatures, gas and liquid flow rates, and source design were investigated to determine their effect on the process of ND-APCI. This paper explores advantages of using ND-APCI for the determination and confirmation of drug residues that might be found in food matrices, including malachite green residues in fish tissue and avermectin residues in milk. PMID:16541409

  1. EVALUATION OF DIPHENYLAMINE DERIVATIVES IN APPLE PEEL USING GRADIENT REVERSED-PHASE LIQUID CHROMATOGRAPHY WITH ULRAVIOLET-VISIBLE ABSORPTION AND ATMOSPHERIC PRESSURE CHEMICAL IONIZATION MASS SELECTIVE DETECTION.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A method was developed for extracting, identifying, and quantifying diphenylamine (DPA) derivatives in the peel of DPA-treated apples using gradient reversed-phase liquid chromatography with ultra-violet/visible absorption and atmospheric pressure chemical ionization detection (LC-UV/vis-APCIMS). C...

  2. Facilities: NHMFL 9.4 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer Citation: Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry

    E-print Network

    Weston, Ken

    : Atmospheric Pressure Laser-Induced Acoustic Desorption Chemical Ionization Mass Spectrometry for Analysis hydrocarbons (the primary components of gasoline) are difficult to analyze by mass spectrometry, because with the ability of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to analyze complex

  3. Analysis of intact tetraether lipids in archaeal cell material and sediments by high performance liquid chromatography\\/atmospheric pressure chemical ionization mass spectrometry

    Microsoft Academic Search

    J. S. Sinninghe Damsté; E. C. Hopmans; S. Schouten; R. D. Pancost; M. T. J. van der Meer

    2000-01-01

    A method combining normal phase high performance liquid chromatography (HPLC) with positive ion atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was developed for the analysis of intact glycerol dialkyl glycerol tetraethers (GDGTs) in archaeal cell material and sediments. All GDGTs previously reported to occur in the thermophilic archaeon Sulfolobus solfataricus could be identified based on their mass spectra and retention

  4. Separation and identification of twelve catechins in tea using liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Zeeb, D J; Nelson, B C; Albert, K; Dalluge, J J

    2000-10-15

    A method has been developed for the direct microscale determination of 12 catechins in green and black tea infusions. The method is based on liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS). Standard catechin mixtures and tea infusions were analyzed by LC/APCI-MS with detection of protonated molecular ions and characteristic fragment ions for each compound. The identities of eight major catechins and caffeine in tea were established based on LC retention times and simultaneously recorded mass spectra. In addition, monitoring of the catechin-specific retro Diels-Alder fragment ion at m/z 139 throughout the chromatogram provided a unique fingerprint for catechin content in the samples that led to the identification of four minor chemically modified catechin derivatives in the infusions. This report is the first to describe the comprehensive determination of all 12 reported catechins in a single analysis. The utility of LC/APCI-MS for providing routine separation and identification of catechins at femtomole to low-picomole levels without extraction or sample pretreatment, and its potential as a standard analytical tool for the determination of polyphenols in natural products and biological fluids, are discussed. PMID:11055724

  5. Atmospheric pressure chemical ionization studies of non-polar isomeric hydrocarbons using ion mobility spectrometry and mass spectrometry with different ionization techniques.

    PubMed

    Borsdorf, H; Nazarov, E G; Eiceman, G A

    2002-09-01

    The ionization pathways were determined for sets of isomeric non-polar hydrocarbons (structural isomers, cis/trans isomers) using ion mobility spectrometry and mass spectrometry with different techniques of atmospheric pressure chemical ionization to assess the influence of structural features on ion formation. Depending on the structural features, different ions were observed using mass spectrometry. Unsaturated hydrocarbons formed mostly [M - 1]+ and [(M - 1)2H]+ ions while mainly [M - 3]+ and [(M - 3)H2O]+ ions were found for saturated cis/trans isomers using photoionization and 63Ni ionization. These ionization methods and corona discharge ionization were used for ion mobility measurements of these compounds. Different ions were detected for compounds with different structural features. 63Ni ionization and photoionization provide comparable ions for every set of isomers. The product ions formed can be clearly attributed to the structures identified. However, differences in relative abundance of product ions were found. Although corona discharge ionization permits the most sensitive detection of non-polar hydrocarbons, the spectra detected are complex and differ from those obtained with 63Ni ionization and photoionization. PMID:12322955

  6. Atmospheric pressure chemical ionization studies of non-polar isomeric hydrocarbons using ion mobility spectrometry and mass spectrometry with different ionization techniques

    NASA Technical Reports Server (NTRS)

    Borsdorf, H.; Nazarov, E. G.; Eiceman, G. A.

    2002-01-01

    The ionization pathways were determined for sets of isomeric non-polar hydrocarbons (structural isomers, cis/trans isomers) using ion mobility spectrometry and mass spectrometry with different techniques of atmospheric pressure chemical ionization to assess the influence of structural features on ion formation. Depending on the structural features, different ions were observed using mass spectrometry. Unsaturated hydrocarbons formed mostly [M - 1]+ and [(M - 1)2H]+ ions while mainly [M - 3]+ and [(M - 3)H2O]+ ions were found for saturated cis/trans isomers using photoionization and 63Ni ionization. These ionization methods and corona discharge ionization were used for ion mobility measurements of these compounds. Different ions were detected for compounds with different structural features. 63Ni ionization and photoionization provide comparable ions for every set of isomers. The product ions formed can be clearly attributed to the structures identified. However, differences in relative abundance of product ions were found. Although corona discharge ionization permits the most sensitive detection of non-polar hydrocarbons, the spectra detected are complex and differ from those obtained with 63Ni ionization and photoionization. c. 2002 American Society for Mass Spectrometry.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  8. Analysis of underivatized amphetamines and related phenethylamines with high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Bogusz, M J; Krüger, K D; Maier, R D

    2000-03-01

    Amphetamine, methamphetamine, illicit designer phenethylamines (MDA, MDEA, MDMA, MBDB, and BDMPEA), and other phenethylamines (benzyl-1-phenylethylamine, cathinone, ephedrine, fenfluramine, norfenfluramine, phentermine, 1-phenylethylamine, phenylpropanolamine, and propylhexedrine) were extracted from serum using a solid-phase extraction procedure. The extracts were examined with high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). The drugs were separated on ODS column in acetonitrile/50 mM ammonium formate buffer (pH 3.0) (25:75) as a mobile phase. Full-scan mass spectra of drugs examined by means of APCI with collision-induced dissociation showed protonated molecular ions and fragments typical for particular drugs. LC-APCI-MS allowed an unequivocal differentiation of all drugs involved. The quantitation was performed using selected ion monitoring of protonated molecular ions and fragments of drugs involved and their deuterated analogues. The limits of detection ranged from 1 to 5 microg/L serum, and the recoveries ranged from 58 to 96%. A linear response was observed for all drugs in the range from 5 to 500 microg/L. The method was applied for routine determination of amphetamine, MDMA, MDA, and MDEA in one run. Solid-phase extraction used assured simultaneous isolation of various groups of basic drugs of forensic interest (opiates, cocaines, phenethylamines, and benzodiazepines) from biofluids. PMID:10732943

  9. Self-Aspirated Atmospheric Pressure Chemical Ionization Source for Direct Sampling of Analytes on Surfaces and in Liquid Solutions

    SciTech Connect

    Asano, Keiji G [ORNL; Ford, Michael J [ORNL; Tomkins, Bruce A [ORNL; Van Berkel, Gary J [ORNL

    2005-01-01

    A self-aspirating heated nebulizer probe is described and demonstrated for use in the direct analysis of analytes on surfaces and in liquid samples by atmospheric pressure chemical ionization (APCI) mass spectrometry. Functionality and performance of the probe as a self-aspirating APCI source is demonstrated using reserpine and progesterone as test compounds. The utility of the probe to sample analytes directly from surfaces was demonstrated first by scanning development lanes of a reversed-phase thin-layer chromatography plate in which a three-component dye mixture, viz., Fat Red 7B, Solvent Green 3, and Solvent Blue 35, was spotted and the components were separated. Development lanes were scanned by the sampling probe operated under computer control (x, y plane) while full-scan mass spectra were recorded using a quadrupole ion trap mass spectrometer. In addition, the ability to sample the surface of pharmaceutical tablets (viz., Extra Strength Tylenol(reg. sign) and Evista(reg. sign) tablets) and to detect the active ingredients (acetaminophen and raloxifene, respectively) selectively was demonstrated using tandem mass spectrometry (MS/MS). Finally, the capability to sample analyte solutions from the wells of a 384-well microtiter plate and to perform quantitative analyses using MS/MS detection was illustrated with cotinine standards spiked with cotinine-d{sub 3} as an internal standard.

  10. Analyses of polycyclic aromatic hydrocarbons in seafood by capillary electrochromatography-atmospheric pressure chemical ionization/mass spectrometry.

    PubMed

    Cheng, Yi-Jie; Huang, Sing-Hao; Chiu, Ju-Yin; Liu, Wan-Ling; Huang, Hsi-Ya

    2013-10-25

    In this work, an on-line preconcentration capillary electrochromatographic (CEC) separation coupled with atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) was used for 16 PAHs analyses, in which poly(stearyl methacrylate-divinylbenzene) (poly(SMA-DVB)) monolith was used as the separation column. With variations in the effective length of poly(SMA-DVB) monolith as well as the volume fraction of acetonitrile (ACN) in the mobile phase, both separation and resolution were improved. A poly(SMA-DVB) monolith of 50-cm effective length (i.e. 50-cm column length filled with polymer) and a two-step step-gradient elution (by changing the ACN levels of the mobile phase starting with an initial of 70% up to 80% with 30-min time interval), which provided baseline separation for PAHs solutes (except for chrysene and benzo[a]anthracene) within 50 min, were employed as the optimal chromatographic conditions. In contrast to the other mass spectrometer parameters (nebulizer gas pressure, vaporizer temperature, corona current) as well as on-line preconcentration parameter (the ACN level in the sample matrix), the sheath liquid composition (methanol/water in the ratio of 3:1) and the sample injection time (40 min) were found as the predominant factors that control the sensitivity of PAHs determination. Finally, this on-line preconcentration CEC-APCI-MS method determined PAH residues in seafood samples successfully with as low as 10 ng/g level. PMID:23992841

  11. Analysis of polycyclic aromatic hydrocarbons using desorption atmospheric pressure chemical ionization coupled to a portable mass spectrometer.

    PubMed

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

    2015-02-01

    Desorption atmospheric pressure chemical ionization (DAPCI) is implemented on a portable mass spectrometer and applied to the direct detection of polycyclic aromatic hydrocarbons (PAHs) and alkyl substituted benzenes. The presence of these compounds in the environment poses a significant threat to the health of both humans and wildlife because of their carcinogenic, toxic, and mutagenic properties. As such, instant detection outside of the laboratory is of particular importance to allow in-situ measurement at the source. Using a rapid, high throughput, miniature, handheld mass spectrometer, several alkyl substituted benzenes and PAHs (i.e., 1,2,3,5-tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, fluoranthene, anthracene, benzo[k]fluoranthene, dibenz[a,h]anthracene, acenaphthene, indeno[1,2,3-c,d]pyrene, 9-ethylfluorene, and 1-benzyl-3-methyl-naphthalene) were identified and characterized using tandem mass spectrometry (MS/MS) from ambient surfaces, in the open air. This method can provide almost instantaneous information while minimizing sample preparation, which is advantageous in terms of both cost and simplicity of analysis. This MS-based technique is applicable to a wide range of environmental organic molecules. PMID:25503470

  12. Are clusters important in understanding the mechanisms in atmospheric pressure ionization? Part 1: Reagent ion generation and chemical control of ion populations.

    PubMed

    Klee, Sonja; Derpmann, Valerie; Wißdorf, Walter; Klopotowski, Sebastian; Kersten, Hendrik; Brockmann, Klaus J; Benter, Thorsten; Albrecht, Sascha; Bruins, Andries P; Dousty, Faezeh; Kauppila, Tiina J; Kostiainen, Risto; O'Brien, Rob; Robb, Damon B; Syage, Jack A

    2014-08-01

    It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region. PMID:24850441

  13. Eddy Correlation Measurements of the Air/Sea Flux of DMS Using Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Marandino, C. A.; Debruyn, W. J.; Saltzman, E. S.

    2003-12-01

    The physical and chemical processes controlling gas exchange across the air/sea interface are not well understood. Many laboratory and field studies of the physical controls on gas exchange have been performed using indirect mass balance measurement techniques, but there have been few direct gas flux measurements over the ocean. Eddy correlation is a micrometeorological technique, which can measure fluxes directly. The use of this technique for trace gas flux measurements has been limited in part due to the lack of sufficiently sensitive, fast-response gas detectors. Atmospheric pressure chemical ionization mass spectrometry (API/CIMS) is a highly sensitive, fast response detection method. We carried out a field study at the Scripps Institute of Oceanography pier to test the use of API/CIMS for eddy correlation flux measurements of dimethylsulfide (DMS). Cospectra of vertical winds and DMS demonstrate that flux from the sea surface was routinely detected. The API/CIMS detected atmospheric fluctuations less than 0.5 Hz. This frequency cut-off probably reflects attenuation in the inlet tubing rather than in the detector itself. The partial pressure of DMS in surface seawater was also determined using the API/CIMS, after equilibration with N2 in a continuous flow membrane equilibrator. Gas exchange coefficients were computed from the flux and air/sea concentration gradient. Gas transfer coefficients determined in this study ranged from 0.66 cm/hr to 38.43 cm/hr, for mean horizontal wind speeds ranging from 1 to 6 m/s. The gas transfer coefficients are positively correlated with wind speed, but are significantly greater than current estimates of gas transfer coefficients at similar wind speeds over the ocean. These elevated gas transfer coefficients probably reflect enhanced water-side turbulence induced by the interaction of wave motion with the shallow bottom at this site.

  14. Regioisomeric analysis of triacylglycerols using silver-ion liquid chromatography–atmospheric pressure chemical ionization mass spectrometry: Comparison of five different mass analyzers

    Microsoft Academic Search

    Michal Hol?apek; Hana Dvo?áková; Miroslav Lísa; Ana Jimenéz Girón; Pat Sandra; Josef Cva?ka

    2010-01-01

    Silver-ion high-performance liquid chromatography (HPLC) coupled to atmospheric pressure chemical ionization mass spectrometry (APCI-MS) is used for the regioisomeric analysis of triacylglycerols (TGs). Standard mixtures of TG regioisomers are prepared by the randomization reaction from 8 mono-acid TG standards (tripalmitin, tristearin, triarachidin, triolein, trielaidin, trilinolein, trilinolenin and tri-gamma-linolenin). In total, 32 different regioisomeric doublets and 11 triplets are synthesized, separated

  15. Analysis of aristolochic acid in nine sources of Xixin, a traditional Chinese medicine, by liquid chromatography\\/atmospheric pressure chemical ionization\\/tandem mass spectrometry

    Microsoft Academic Search

    Ting-Ting Jong; Maw-Rong Lee; Shun-Sheng Hsiao; Jar-Lung Hsai; Tian-Shung Wu; Shu Tuan Chiang; Shao-Qing Cai

    2003-01-01

    Aristolochic acid I (AA-I), which is a known nephrotoxin, is found in a commonly used Chinese medicine, Xixin, that originates from nine Asarum species (Aristolochiaceae) found in China. A method has been developed using reversed-phase liquid chromatography coupled with atmospheric pressure chemical ionization (APCI) tandem mass spectrometry under the positive ion detection mode [LC\\/(+)APCI\\/MS\\/MS] to determine the amount of AA-I

  16. Characterization of triacylglycerol and diacylglycerol composition of plant oils using high-performance liquid chromatography–atmospheric pressure chemical ionization mass spectrometry

    Microsoft Academic Search

    Michal Hol?apek; Pavel Jandera; Petr Zderadi?ka; Lucie Hrubá

    2003-01-01

    Triacylglycerols (TGs) and diacylglycerols (DGs) in 16 plant oil samples (hazelnut, pistachio, poppy-seed, almond, palm, Brazil-nut, rapeseed, macadamia, soyabean, sunflower, linseed, Dracocephalum moldavica, evening primrose, corn, amaranth, Silybum arianum) were analyzed by HPLC–MS with atmospheric pressure chemical ionization (APCI) and UV detection at 205 nm on two Nova-Pak C18 chromatographic columns connected in series. A single chromatographic column and non-aqueous

  17. Rapid and sensitive analysis of azadirachtin and related triterpenoids from Neem ( Azadirachta indica) by high-performance liquid chromatography–atmospheric pressure chemical ionization mass spectrometry

    Microsoft Academic Search

    Otmar Schaaf; Andrew P Jarvis; S. Andrew van der Esch; Germina Giagnacovo; Neil J Oldham

    2000-01-01

    Based on reversed-phase high-performance liquid chromatography (RP-HPLC) and atmospheric pressure chemical ionization (APCI) mass spectrometry, a HPLC–MS method was developed to permit the rapid qualitative and quantitative analysis of azadirachtin and related tetranortriterpenoids from seeds and tissue cultures of Neem (Azadirachta indica). APCI+ standard scanning mass spectra of the major Neem triterpenoids were recorded and utilized to select suitable ions

  18. Improved quantitative detection of 11 urinary phthalate metabolites in humans using liquid chromatography–atmospheric pressure chemical ionization tandem mass spectrometry

    Microsoft Academic Search

    Manori J Silva; Nicole A Malek; Carolyn C Hodge; John A Reidy; Kayoko Kato; Dana B Barr; Larry L Needham; John W Brock

    2003-01-01

    Phthalates are widely used as industrial solvents and plasticizers, with global use exceeding four million tons per year. We improved our previously developed high-performance liquid chromatography–atmospheric pressure chemical ionization-tandem mass spectrometric (HPLC–APCI-MS\\/MS) method to measure urinary phthalate metabolites by increasing the selectivity and the sensitivity by better resolving them from the solvent front, adding three more phthalate metabolites, monomethyl phthalate

  19. Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry†

    PubMed Central

    Jin, Zhicheng; Daiya, Shivani; Kenttämaa, Hilkka I.

    2011-01-01

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H2O)+ chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5?-cholestane, cholesta-3,5-diene, squalene, and ?-carotene, were found to solely form the desired water replacement product (adduct-H2O) with the ClMn(H2O)+ ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H2O ions, but less abundant adduct-2H2O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H2O)+ chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids. PMID:21528012

  20. Characterization of nonpolar lipids and steroids by using laser-induced acoustic desorption/chemical ionization, atmospheric pressure chemical ionization, and electrospray ionization mass spectrometry

    SciTech Connect

    Jin, Z.; Daiya, S.; Kenttämaa, Hilkka I.

    2011-01-01

    Laser-induced acoustic desorption (LIAD) combined with ClMn(H{sub 2}O){sup +} chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5?-cholestane, cholesta-3,5-diene, squalene, and ?-carotene, were found to solely form the desired water replacement product (adduct-H{sub 2}O) upon reaction with the ClMn(H{sub 2}O){sup +} ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H{sub 2}O ions, but less abundant adduct-2H{sub 2}O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H{sub 2}O){sup +} chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids.

  1. Cyclic acyloxonium ions as diagnostic aids in the characterization of chloropropanol esters under electron impact (EI), electrospray ionization (ESI), and atmospheric pressure chemical ionization (APCI) conditions.

    PubMed

    Rahn, Anja K K; Yaylayan, Varoujan A

    2013-06-26

    During mass spectrometric analysis of various lipids and lipid derivatives such as the chlorinated counterparts of triacylglycerols, the detailed structure of the characteristic and common ions formed under electron impact (EI), electrospray ionization (ESI), and atmospheric pressure chemical ionization (APCI) conditions by the loss of a single fatty acid remains ambiguous. These ions are designated in the literature as "diacylglyceride ions" and are frequently depicted with a molecular formula without showing any structural features and sometimes represented as cyclic acyloxonium ions. Characterization of these ions is of considerable importance due to their utility in structural identification of lipid derivatives. This study provides complementary evidence on the cyclic nature of "diacylglyceride ions" through the use of the simplest 3-monochloropropanediol diester as a model and the use of isotope labeling technique. Tandem MS/MS studies have indicated that the ion at m/z 135.6 generated from 1,2-bis(acetoyl)-3-chloropropane through the loss of an acetyl group was identical to the ion at m/z 135.6 generated from 4-chloromethyl-2,2-dimethyl-1,3-dioxolane, the latter being generated from a cyclic precursor through the loss of a methyl radical, keeping the dioxolane ring structure intact, thus confirming the cyclic nature of these ions. The corresponding cyclic oxonium ions generated from longer chain chloropropanol diesters, such as the ion at m/z 331.2 originating from 3-monochloropropanediol (3-MCPD) diesters containing palmitic acid(s), could serve as chemical markers for the presence chloropropanol esters. PMID:23734847

  2. Liquid chromatography\\/atmospheric pressure ionization-mass spectrometry in drug metabolism studies

    Microsoft Academic Search

    R. Kostiainen; T. Kotiaho; T. Kuuranne; S. Auriola

    2003-01-01

    Thestudyofthemetabolicfateofdrugs isanessentialand importantpartofthedrug developmentprocess. The analysis of metabolites is a challenging task and several different analytical methods have been used in these studies. However, after the introduction of the atmospheric pressure ionization (API) technique, electrospray and atmospheric pressure chemical ionization, liquid chromatography\\/mass spectrometry (LC\\/MS) has become an important and widely used method in the analysis of metabolites owing to its

  3. Differentiation of regioisomeric aromatic ketocarboxylic acids by atmospheric pressure chemical ionization CAD tandem mass spectrometry in a linear quadrupole ion trap mass spectrometer

    SciTech Connect

    Amundson, Lucas M.; Owen, Ben C.; Gallardo, Vanessa A.; Habicht, S. C.; Fu, M.; Shea, R. C.; Mossman, A. B.; Kenttämaa, Hilkka I.

    2011-01-01

    Positive-mode atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS n ) was tested for the differentiation of regioisomeric aromatic ketocarboxylic acids. Each analyte forms exclusively an abundant protonated molecule upon ionization via positive-mode APCI in a commercial linear quadrupole ion trap (LQIT) mass spectrometer. Energy-resolved collision-activated dissociation (CAD) experiments carried out on the protonated analytes revealed fragmentation patterns that varied based on the location of the functional groups. Unambiguous differentiation between the regioisomers was achieved in each case by observing different fragmentation patterns, different relative abundances of ion-molecule reaction products, or different relative abundances of fragment ions formed at different collision energies. The mechanisms of some of the reactions were examined by H/D exchange reactions and molecular orbital calculations.

  4. Medium resolution atmospheric pressure ionization mass spectrometer

    NASA Astrophysics Data System (ADS)

    Grange, Andrew H.; O'Brien, Robert J.; Barofsky, Douglas F.

    1988-04-01

    An atmospheric pressure ionization (API) source for a VG 7070E-HF mass spectrometer has been built and successfully operated at an accelerating potential of 6 kV. Hydrated protons and hydrated organic ions formed in the API source can be either partially or completely disaggregated by collisionally induced dissociation before entering the mass analyzer. The protonated molecular ions of pinacolone and 2,4-pentanedione can be fully separated (R=2800, m/z 101, <1% valley) at one sixth of their maximum signal strengths, and the 13C-xylene radical ion and protonated benzaldehyde can be fully separated (R=3300, m/z 107, <1% valley) at one tenth of their maximum signal strengths. With 1% transmission, the resolving power of the VG 7070E-HF operating in the API mode is estimated to be 4800 (m/z 92, 10% valley). This resolution is more than sufficient to separate two oxidized hydrocarbons whose masses differ by 0.0364 daltons, the difference between a -CH2CH2- group and a >CO group, and to permit unambiguous assignment of their molecular formulas. No other form of API mass spectrometer, including the triple quadrupole version, has this capability.

  5. Fast determination of 3-ethenylpyridine as a marker of environmental tobacco smoke at trace level using direct atmospheric pressure chemical ionization tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jiang, Cheng-Yong; Sun, Shi-Hao; Zhang, Qi-Dong; Liu, Jun-Hui; Zhang, Jian-Xun; Zong, Yong-Li; Xie, Jian-Ping

    2013-03-01

    A method with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) was developed and applied to direct analysis of Environmental Tobacco Smoke (ETS), using 3-ethenylpyridine (3-EP) as a vapour-phase marker. In this study, the ion source of APCI-MS/MS was modified and direct analysis of gas sample was achieved by the modified instrument. ETS samples were directly introduced, via an atmospheric pressure inlet, into the APCI source. Ionization was carried out in positive-ion APCI mode and 3-EP was identified by both full scan mode and daughter scan mode. Quantification of 3-EP was performed by multiple reaction monitoring (MRM) mode. The calibration curve was obtained in the range of 1-250 ng L-1 with a satisfactory regression coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.5 ng L-1 and 1.6 ng L-1, respectively. The precision of the method, calculated as relative standard deviation (RSD), was characterized by repeatability (RSD 3.92%) and reproducibility (RSD 4.81%), respectively. In real-world ETS samples analysis, compared with the conventional GC-MS method, the direct APCI-MS/MS has shown better reliability and practicability in the determination of 3-EP at trace level. The developed method is simple, fast, sensitive and repeatable; furthermore, it could provide an alternative way for the determination of other volatile pollutants in ambient air at low levels.

  6. Simultaneous detection of polar and nonpolar compounds by ambient mass spectrometry with a dual electrospray and atmospheric pressure chemical ionization source.

    PubMed

    Cheng, Sy-Chyi; Jhang, Siou-Sian; Huang, Min-Zong; Shiea, Jentaie

    2015-02-01

    A dual ionization source combining electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) was developed to simultaneously ionize both polar and nonpolar compounds. The source was constructed by inserting a fused silica capillary into a stainless steel column enclosed in a glass tube. A high dc voltage was applied to a methanol solution flowing in the fused silica capillary to generate an ESI plume at the capillary tip. A high ac voltage was applied to a ring electrode attached to the glass tube to generate plasma from the nitrogen gas flowing between the glass tube and the stainless steel column. The concentric arrangement of the ESI plume and the APCI plasma in the source ensured that analytes entering the ionization region interacted with both ESI and APCI primary ion species generated in the source. Because the high voltages required for ESI and APCI were independently applied and controlled, the dual ion source could be operated in ESI-only, APCI-only, or ESI+APCI modes. Analytes were introduced into the ESI and/or APCI plumes by irradiating sample surfaces with a continuous-wavelength laser or a pulsed laser beam. Analyte ions could also be produced by directing the dual ESI+APCI source toward sample surfaces for desorption and ionization. The ionization mechanisms involved in the dual ion source include Penning ionization, ion molecule reactions, and fused-droplet electrospray ionization. Standards of polycyclic aromatic hydrocarbons, angiotensin I, lidocaine, ferrocene, diesel, and rosemary oils were used for testing. Protonated analyte ions were detected in ESI-only mode, radical cations were detected in APCI-only mode, and both types of ions were detected in ESI+APCI mode. PMID:25562530

  7. High-throughput walkthrough detection portal for counter terrorism: detection of triacetone triperoxide (TATP) vapor by atmospheric-pressure chemical ionization ion trap mass spectrometry.

    PubMed

    Takada, Yasuaki; Nagano, Hisashi; Suzuki, Yasutaka; Sugiyama, Masuyuki; Nakajima, Eri; Hashimoto, Yuichiro; Sakairi, Minoru

    2011-09-15

    With the aim of improving security, a high-throughput portal system for detecting triacetone triperoxide (TATP) vapor emitted from passengers and luggage was developed. The portal system consists of a push-pull air sampler, an atmospheric-pressure chemical ionization (APCI) ion source, and an explosives detector based on mass spectrometry. To improve the sensitivity of the explosives detector, a novel linear ion trap mass spectrometer with wire electrodes (wire-LIT) is installed in the portal system. TATP signals were clearly obtained 2?s after the subject under detection passed through the portal system. Preliminary results on sensitivity and throughput show that the portal system is a useful tool for preventing the use of TATP-based improvised explosive devices by screening persons in places where many people are coming and going. PMID:21818804

  8. Monitoring of antifouling agents in water samples by on-line solid-phase extraction-liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Gimeno, R A; Aguilar, C; Marcé, R M; Borrull, F

    2001-04-27

    An automatic method for determining diuron, irgarol 1051, folpet and dichlofluanid in seawater samples have been developed. This method is based on the on-line coupling of solid-phase extraction (SPE) with a highly crosslinked polymeric sorbent, LiChrolut EN, to liquid chromatography followed by atmospheric pressure chemical ionization (APCI) and mass spectrometry. The operational parameters affecting the APCI interface have been studied in both positive and negative ionization modes. The use of LiChrolut EN in the SPE produced recoveries of over 85% for all the compounds when 100 ml of seawater sample was preconcentrated. Calibration was carried out in both ionization modes and in full-scan and selected-ion monitoring (SIM). The method allowed all the analytes to be detected at 5 ng l(-1) in SIM acquisition mode except folpet, which, because of its low response, could only be detected at 250 ng l(-1). The method was used to analyse water samples taken from five different marina and fishing ports along the coast of Tarragona, Catalonia (Spain), over a 5-month period. Diuron and irgarol 1051 were detected and quantified in most samples at concentration levels ranging from 27 to 420 ng l(-1) for diuron and from 15 to 511 ng l(-1) for irgarol 1051. PMID:11358242

  9. Potential of gas chromatography-atmospheric pressure chemical ionization-time-of-flight mass spectrometry for the determination of sterols in human plasma.

    PubMed

    Matysik, S; Schmitz, G; Bauer, S; Kiermaier, J; Matysik, F-M

    2014-04-11

    The application of Gas Chromatography (GC)-Atmospheric Pressure Chemical Ionization (APCI)-Time-of-Flight Mass Spectrometry (TOF-MS) is presented for sterol analysis in human plasma. A commercial APCI interface was modified to ensure a well-defined humidity which is essential for controlled ionization. In the first step, optimization regarding flow rates of auxiliary gases was performed by using a mixture of model analytes. Secondly, the qualitative and quantitative analysis of sterols including oxysterols, cholesterol precursors, and plant sterols as trimethylsilyl-derivatives was successfully carried out. The characteristics of APCI together with the very good mass accuracy of TOF-MS data enable the reliable identification of relevant sterols in complex matrices. Linear calibration lines and plausible results for healthy volunteers and patients could be obtained whereas all mass signals were extracted with an extraction width of 20 ppm from the full mass data set. One advantage of high mass accuracy can be seen in the fact that from one recorded run any search for m/z can be performed. PMID:24463103

  10. Characterization of triacylglycerol and diacylglycerol composition of plant oils using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Holcapek, Michal; Jandera, Pavel; Zderadicka, Petr; Hrubá, Lucie

    2003-08-29

    Triacylglycerols (TGs) and diacylglycerols (DGs) in 16 plant oil samples (hazelnut, pistachio, poppy-seed, almond, palm, Brazil-nut, rapeseed, macadamia, soyabean, sunflower, linseed, Dracocephalum moldavica, evening primrose, corn, amaranth, Silybum arianum) were analyzed by HPLC-MS with atmospheric pressure chemical ionization (APCI) and UV detection at 205 nm on two Nova-Pak C18 chromatographic columns connected in series. A single chromatographic column and non-aqueous ethanol-acetonitrile gradient system was used as a compromise between the analysis time and the resolution for the characterization of TG composition of five plant oils. APCI mass spectra were applied for the identification of all TGs and other acylglycerols. The isobaric positional isomers can be distinguished on the basis of different relative abundances of the fragment ions formed by preferred losses of the fatty acid from sn-1(3) positions compared to the sn-2 position. Excellent chromatographic resolution and broad retention window together with APCI mass spectra enabled positive identification of TGs containing fatty acids with odd numbers of carbon atoms such as margaric (C17:0) and heptadecanoic (C17:1) acids. The general fragmentation patterns of TGs in both APCI and electrospray ionization mass spectra were proposed on the basis of MSn spectra measured with an ion trap analyzer. The relative concentrations of particular TGs in the analyzed plant oils were estimated on the basis of relative peak areas measured with UV detection at 205 nm. PMID:12974290

  11. Online atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-IT-MSn) for measuring organic acids in concentrated bulk aerosol - a laboratory and field study

    NASA Astrophysics Data System (ADS)

    Vogel, A. L.; Äijälä, M.; Brüggemann, M.; Ehn, M.; Junninen, H.; Petäjä, T.; Worsnop, D. R.; Kulmala, M.; Williams, J.; Hoffmann, T.

    2012-08-01

    The field application of an aerosol concentrator in conjunction with an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) at the boreal forest station SMEAR II at Hyytiälä, Finland, is demonstrated in this study. APCI is a soft ionization technique allowing online measurements of organic acids in the gas and particle phase. The detection limit for the acid species in the particle phase was increased by a factor of 7.5 to 11 (e.g. ~40 ng m-3 for pinonic acid) by using the miniature Versatile Aerosol Concentration Enrichment System (mVACES) upstream of the mass spectrometer. The APCI-IT-MS was calibrated in the negative ion mode with two biogenic organic acid standards - pinic acid and pinonic acid. Pinic acid was used as a surrogate for the quantification of the total amount of organic acids in the ambient aerosol based on the total signal intensities in the negative ion mode. The results were compared with the total organic signal of a C-ToF-AMS during the HUMPPA-COPEC 2010 field campaign. The campaign average contribution of organic acids measured by APCI-IT-MS to the total sub-micron organic aerosol mass was estimated to be about 60%. Very good correlation between APCI-IT-MS and C-ToF-AMS (Pearson's R = 0.94) demonstrates soft ionization mass spectrometry as a complimentary technique to AMS with electron impact ionization. MS2 studies of specific m/z ratios recorded during the HUMPPA-COPEC 2010 field campaign were compared to MS2 studies of selected monoterpene oxidation products formed in simulation chamber experiments. The comparison of the resulting fragments shows that oxidation products of the main VOCs emitted at Hyytiälä (?-pinene and ?3-carene) cannot account for all of the measured fragments, which illustrates the complexity of ambient aerosol and possibly indicates unidentified or underestimated biogenic SOA precursor in the boreal forest.

  12. Method for determination of acephate, methamidophos, omethoate, dimethoate, ethylenethiourea and propylenethiourea in human urine using high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    Montesano, M Angela; Olsson, Anders O; Kuklenyik, Peter; Needham, Larry L; Bradman, A S A; Barr, Dana B

    2007-07-01

    Because of increasing concern about widespread use of insecticides and fungicides, we have developed a highly sensitive analytical method to quantify urine-specific urinary biomarkers of the organophosphorus pesticides acephate, methamidophos, omethoate, dimethoate, and two metabolites from the fungicides alkylenebis-(dithiocarbamate) family: ethylenethiourea and propylenethiourea. The general sample preparation included lyophilization of the urine samples followed by extraction with dichloromethane. The analytical separation was performed by high-performance liquid chromatography (HPLC), and detection by a triple quadrupole mass spectrometer with and atmospheric pressure chemical ionization source in positive ion mode using multiple reaction monitoring and tandem mass spectrometry (MS/MS) analysis. Two different Thermo-Finnigan (San Jose, CA, USA) triple quadrupole mass spectrometers, a TSQ 7,000 and a TSQ Quantum Ultra, were used in these analyses; results are presented comparing the method specifications of these two instruments. Isotopically labeled internal standards were used for three of the analytes. The use of labeled internal standards in combination with HPLC-MS/MS provided a high degree of selectivity and precision. Repeated analysis of urine samples spiked with high, medium and low concentration of the analytes gave relative standard deviations of less than 18%. For all compounds the extraction efficiency ranged between 52% and 63%, relative recoveries were about 100%, and the limits of detection were in the range of 0.001-0.282 ng/ml. PMID:17440487

  13. A method for simultaneous analysis of phytosterols and phytosterol esters in tobacco leaves using non aqueous reversed phase chromatography and atmospheric pressure chemical ionization mass spectrometry detector.

    PubMed

    Ishida, Naoyuki

    2014-05-01

    While numerous analytical methods for phytosterols have been reported, the similar polarity and large molecules of phytosterol esters have made the methods lengthy and complicated. For this reason, an analytical method that could completely separate phytosterol esters including the higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid in addition to phytosterols without preliminary separation was developed. The separation was accomplished by non-aqueous reversed phase chromatography technique using only acetone and acetonitrile. An atmospheric pressure chemical ionization/mass spectrometry detector configured at selected ion monitoring mode was hyphenated with the separation system to detect phytosterols and phytosterol esters. Twenty-four types of these were consequently separated and then identified with their authentic components. The calibration curve was drawn in the range of about 5 to 25,000 ng/mL with a regression coefficient over 0.999. The limit of detection and limit of quantification, respectively, ranged from 0.9 to 3.0 ng/mL and from 3.0 to 11.0 ng/mL. Recovery rates ranged from 80 to 120%. The quantification results were subjected to statistical analysis and hierarchical clustering analysis, and were used to determine the differences in the amounts of phytosterols and phytosterol esters across tobacco leaves. The newly developed method succeeded in clarifying the whole composition of phytosterols and phytosterol esters in tobacco leaves and in explaining compositional differences across the variety of tobacco leaves. PMID:24690307

  14. Analysis of 1,2-diol diesters in vernix caseosa by high-performance liquid chromatography - atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Šub?íková, Lenka; Hoskovec, Michal; Vrkoslav, Vladimír; ?melíková, Tereza; Háková, Eva; Míková, Radka; Coufal, Pavel; Doležal, Antonín; Plavka, Richard; Cva?ka, Josef

    2015-01-23

    Fatty acid diesters of long-chain 1,2-diols (1,2-DDE), or type II wax diesters, were analyzed in the vernix caseosa of a newborn girl. 1,2-DDE were isolated from the total lipid extract by the semipreparative TLC using plates coated with silica gel. Chromatographic separation of the 1,2-DDE molecular species was achieved on the non-aqueous reversed-phase HPLC with two Nova-Pak C18 columns connected in series (a total length of 45cm) and using an acetonitrile-ethyl acetate gradient. 1,2-DDE eluted from the column in the order of their equivalent chain number. The analytes were detected as ammonium adducts by an ion-trap mass spectrometer equipped with an atmospheric pressure chemical ionization source. Their structures were elucidated using tandem mass spectrometry with MS, MS(2) and MS(3) steps in a data-dependent mode. More than two thousand molecular species of 1,2-DDE were identified in 141 chromatographic peaks. The most abundant 1,2-DDE were monounsaturated lipids consisting of a C22 diol and a C18:1 fatty acid together with C16:0, C14:0 or C15:0 fatty acids. The positions of double bonds were characterized by the fragmentation of [M+C3H5N](+) formed in the ion source. PMID:25555408

  15. [Determination of aliphatic amines by high performance liquid chromatography with fluorescence and atmospheric pressure chemical ionization detection and identification by mass spectrometry].

    PubMed

    Chen, Xiangming; Shi, Yunwei; Zhao, Xian'en; Zhang, Haifeng; You, Jinmao

    2005-11-01

    Aliphatic amines exist widely in nature. Therefore, quick and precise determination of aliphatic amines is of great significance. A simple and highly sensitive method based on the derivatization of aliphatic amines utilizing 1,2-benzo-3,4-dihydrocarbazole-9-acetic acid (BCAA) as the novel pre-column derivatization reagent followed by high performance liquid chromatography with fluorescence detection and online mass spectrometric identification was developed. Optimum derivatization was obtained by the reaction of aliphatic amines with BCAA at 50 degrees C for 15 min in the presence of 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDAC) in acetonitrile solvent. The condition of derivatization was mild and the yield of derivative each aliphatic amine was higher than 94%. Derivatives were sufficiently stable to be efficiently analyzed by high performance chromatography without pretreatment. On a reversed-phase BDS-C18 column, twelve aliphatic amine derivatives (C8 - C12) were separated under gradient elution with baseline resolution. The precise determining aliphatic amines from soil and wastewater samples was obtained by post-column online mass spectrometric identification with atmospheric pressure chemical ionization (APIC) source under positive mode detection. The established method exhibited excellent reproducibility and recovery. Linear responses were observed with coefficients over 0.999 3. The detection limits (at signal-to-noise ratio of 3: 1) were 12 - 28 fmol. PMID:16498997

  16. Carbamazepine in municipal wastewater and wastewater sludge: ultrafast quantification by laser diode thermal desorption-atmospheric pressure chemical ionization coupled with tandem mass spectrometry.

    PubMed

    Mohapatra, D P; Brar, S K; Tyagi, R D; Picard, P; Surampalli, R Y

    2012-09-15

    In this study, the distribution of the anti-epileptic drug carbamazepine (CBZ) in wastewater (WW) and aqueous and solid phases of wastewater sludge (WWS) was carried out. A rapid and reliable method enabling high-throughput sample analysis for quicker data generation, detection, and monitoring of CBZ in WW and WWS was developed and validated. The ultrafast method (15s per sample) is based on the laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to tandem mass spectrometry (MS/MS). The optimization of instrumental parameters and method application for environmental analysis are presented. The performance of the novel method was evaluated by estimation of extraction recovery, linearity, precision and detection limit. The method detection limits was 12 ng L(-1) in WW and 3.4 ng g(-1) in WWS. The intra- and inter-day precisions were 8% and 11% in WW and 6% and 9% in WWS, respectively. Furthermore, three extraction methods, ultrasonic extraction (USE), microwave-assisted extraction (MAE) and accelerated solvent extraction (ASE) with three different solvent condition such as methanol, acetone and acetonitrile:ethyle acetate (5:1, v/v) were compared on the basis of procedural blank and method recovery. Overall, ASE showed the best extraction efficiency with methanol as compared to USE and MAE. Furthermore, the quantification of CBZ in WW and WWS samples showed the presence of contaminant in all stages of the treatment plant. PMID:22967548

  17. Identification and quantification of antitumor thioproline and methylthioproline in Korean traditional foods by a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

    PubMed

    Kim, Sun Hyo; Kim, Hyun-Ji; Shin, Ho-Sang

    2014-11-01

    A liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometric method (LC-APCI-MS/MS) has been developed for the sensitive determination of antitumor thioproline and methylthioproline from fermented foods. Thioproline and methylthioproline were derivatized in one step with ethyl chloroformate at room temperature. These compounds were identified and quantified in various traditional Korean fermented foods by LC-APCI-MS/MS. The concentration range of thioproline of each food was found for doenjang (0.011-0.032mg/kg), gochujang (0.010-0.038mg/kg), and ganjang (0.010-0.038mg/kg). Those of methylthioproline of each food was found for doenjang (0.098-0.632mg/kg), gochujang (0.015-0.112mg/kg), and ganjang (0.023-1.468mg/kg). A prolonged aging time leads to an increase in both the thioproline and methylthioproline contents, suggesting that the storage time plays a key role in the formation of thioproline and methylthioproline in Korean traditional foods. The results here suggest that thioproline and methylthioproline are related to the biological activities of traditional Korean fermented foods. PMID:25128876

  18. Online atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-IT-MSn) for measuring organic acids in concentrated bulk aerosol - a laboratory and field study

    NASA Astrophysics Data System (ADS)

    Vogel, A. L.; Äijälä, M.; Brüggemann, M.; Ehn, M.; Junninen, H.; Petäjä, T.; Worsnop, D. R.; Kulmala, M.; Williams, J.; Hoffmann, T.

    2013-02-01

    The field application of an aerosol concentrator in conjunction with an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) at the boreal forest station SMEAR II at Hyytiälä, Finland, is demonstrated in this study. APCI is a soft-ionization technique allowing online measurements of organic acids in the gas and particle phase. The detection limit for the acid species in the particle phase was improved by a factor of 7.5 to 11 (e.g. ∼40 ng m3 for pinonic acid) by using the miniature versatile aerosol concentration enrichment system (mVACES) upstream of the mass spectrometer. The APCI-IT-MS was calibrated in the negative ion mode with two biogenic organic acid standards - pinic acid and pinonic acid. Pinic acid was used as a surrogate for the quantification of the total amount of organic acids in the ambient aerosol based on the total signal intensities in the negative ion mode. The results were compared with the total organic signal of a C-ToF-AMS during the HUMPPA-COPEC 2010 field campaign. The campaign average contribution of organic acids measured by APCI-IT-MS to the total submicron organic aerosol mass was estimated to be about 60%, based on the response of pinic acid. Very good correlation between APCI-IT-MS and C-ToF-AMS (Pearson's R = 0.94) demonstrates soft-ionization mass spectrometry as a complimentary technique to AMS with electron impact ionization. MS2 studies of specific m/z ratios recorded during the HUMPPA-COPEC 2010 field campaign were compared to MS2 studies of selected monoterpene oxidation products formed in simulation chamber experiments. The comparison of the resulting fragments shows that oxidation products of the main VOCs emitted at Hyytiälä (?-pinene and ?3-carene) cannot account for all of the measured fragments. Possible explanations for those unaccounted fragments are the presence of unidentified or underestimated biogenic SOA precursors, or that different products are formed by a different oxidant mixture of the ambient air compared to the chamber ozonolysis.

  19. Quantitative analysis of levamisole in porcine tissues by high-performance liquid chromatography combined with atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Cherlet, M; De Baere, S; Croubels, S; De Backer, P

    2000-06-01

    This work presents the development and the validation of an LC-MS-MS method with atmospheric pressure chemical ionization for the quantitative determination of levamisole, an anthelmintic for veterinary use, in porcine tissue samples. A liquid-liquid back extraction procedure using hexane-isoamylalcohol (95:5, v/v) as extraction solvent was followed by a solid-phase extraction procedure using an SCX column to clean up the tissue samples. Methyllevamisole was used as the internal standard. Chromatographic separation was achieved on a LiChrospher 60 RP-select B (5 microm) column using a mixture of 0.1 M ammonium acetate in water and acetonitrile as the mobile phase. The mass spectrometer was operated in MS-MS full scanning mode. The method was validated for the analysis of various porcine tissues: muscle, kidney, liver, fat and skin plus fat, according to the requirements defined by the European Community. Calibration graphs were prepared for all tissues and good linearity was achieved over the concentration ranges tested (r>0.99 and goodness of fit <10%). Limits of quantification of 5.0 ng/g were obtained for the analysis of levamisole in muscle, kidney, fat and skin plus fat tissues, and of 50.0 ng/g for liver analysis, which correspond in all cases to half the MRLs (maximum residue limits). Limits of detection ranged between 2 and 4 ng/g tissue. The within-day and between-day precisions (RSD, %) and the results for accuracy fell within the ranges specified. The method has been successfully used for the quantitative determination of levamisole in tissue samples from pigs medicated via drinking water. Moreover the product ion spectra of the levamisole peak in spiked and incurred tissue samples were in close agreement (based on ion ratio measurements) with those of standard solutions, indicating the worthiness of the described method for pure qualitative purposes. PMID:10901133

  20. Characterization of triglycerides in vegetable oils by silver-ion packed-column supercritical fluid chromatography coupled to mass spectroscopy with atmospheric pressure chemical ionization and coordination ion spray

    Microsoft Academic Search

    P. Sandra; A. Medvedovici; Y. Zhao; F. David

    2002-01-01

    Characterization of triglycerides in vegetable oils was achieved by silver-ion packed-column supercritical fluid chromatography (SI-pSFC) with mass spectrometric detection. Hyphenation was made using commercially available liquid chromatography–mass spectrometry (LC–MS) interfaces without any modification. A make-up fluid was delivered through a T-piece placed before or after the SFC restrictor by means of a high pressure pump. Atmospheric pressure chemical ionization (APCI)

  1. Rapid quantitation of plasma 2'-deoxyuridine by high-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry and its application to pharmacodynamic studies in cancer patients.

    PubMed

    Li, Kong M; Rivory, Laurent P; Clarke, Stephen J

    2005-06-01

    A novel method employing high-performance liquid chromatograph-mass spectrometry (LC-MS) has been developed and validated for the quantitation of plasma 2'-deoxyuridine (UdR). It involves a plasma clean-up step with strong anion-exchange solid-phase extraction (SAX-SPE) followed by HPLC separation and atmospheric pressure chemical ionization mass spectrometry detection (APCI-MS) in a selected-ion monitoring (SIM) mode. The ionization conditions were optimised in negative ion mode to give the best intensity of the dominant formate adduct [M+HCOO]- at m/z 273. Retention times were 7.5 and 12.5 min for 2'-deoxyuridine and 5-iodo-2'-deoxyuridine, an iodinated analogue internal standard (IS), respectively. Peak area ratios of 2'-deoxyuridine to IS were used for regression analysis of the calibration curve. The latter was linear from 5 to 400 nmol/l using 1 ml sample volume of plasma. The average recovery was 81.5% and 78.6% for 2'-deoxyuridine and 5-iodo-deoxyuridine, respectively. The method provides sufficient sensitivity, precision, accuracy and selectivity for routine analysis of human plasma 2'-deoxyuridine concentration with the lowest limit of quantitation (LLOQ) of 5 nmol/l. Clinical studies in cancer patients treated with the new fluoropyrimidine analogue capecitabine (N4-pentoxycarbonyl-5'-5-fluorocytidine) have shown that plasma 2'-deoxyuridine was significantly elevated after 1 week of treatment, consistent with inhibition of thymidylate synthase (TS). These findings suggest that the mechanism of antiproliferative toxicity of capecitabine is at least partly due to TS inhibitory activity of its active metabolite 5-fluoro-2'-deoxyuridine monophosphate (FdUMP). Monitoring of plasma UdR concentrations have the potential to help clinicians to guide scheduling of capecitabine or other TS inhibitors in clinical trials. Marked differences of plasma 2'-deoxyuridine between human and rodents have also been confirmed. In conclusion, the LC-MS method developed is simple, highly selective and sensitive and permits pharmacodynamic studies of TS inhibitors in several species. PMID:15866500

  2. Ultra-high performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry for the analysis of benzimidazole compounds in milk samples.

    PubMed

    Martínez-Villalba, Anna; Moyano, Encarnación; Galceran, Maria Teresa

    2013-10-25

    In this work the atmospheric pressure ionization behavior and the tandem mass spectrometry fragmentation of 19 benzimidazoles was studied. Several atmospheric pressure ionization (API) sources (ESI, APCI and APPI) were evaluated showing that APCI was the best option, mainly for KETO-TCB that provided a 20 times improvement versus ESI. From the studies of tandem mass spectrometry, fragmentation pathways were proposed thus characterizing the most abundant and interesting product ions and selecting the most abundant and selective ones for the confirmatory quantitative method performed in SRM mode in a triple quadrupole mass analyzer. For quantitative analysis, the 19 benzimidazoles were separated in less than 7 min using a C18 column packed with superficially porous particles providing high efficiency within the range of UHPLC. A QuEChERS-like sample treatment was applied to milk samples before the UHPLC-APCI-MS/MS determination providing method limits of quantitation that ranged from 0.6 to 3 ?g kg(-1) and showing good repeatability (RSD: 2-18%) and accuracy (relative errors: 1-23%) suitable for using this method for routine analysis. PMID:24035105

  3. Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

    PubMed

    Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

    2013-11-01

    In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. PMID:24259213

  4. Analysis of organic aerosols using a micro-orifice volatilization impactor coupled to an atmospheric-pressure chemical ionization mass spectrometer.

    PubMed

    Brüggemann, Martin; Vogel, Alexander Lucas; Hoffmann, Thorsten

    2014-01-01

    We present the development and characterization of a combination of a micro-orifice volatilization impactor (MOVI) and an ion trap mass spectrometer (IT/MS) with an atmospheric-pressure chemical ionization (APCI) source. The MOVI is a multi-jet impactor with 100 nozzles, allowing the collection of aerosol particles by inertial impaction on a deposition plate. The pressure drop behind the nozzles is approximately 5%, resulting in a pressure of 96kPa on the collection surface for ambient pressures of 101.3 kPa. The cut-point diameter (diameter of 50% collection efficiency) is at 0.13 microm for a sampling flow rate of 10 L min(-1). After the collection step, aerosol particles are evaporated by heating the impaction surface and transferred into the APCI-IT/MS for detection of the analytes. APCI was used in the negative ion mode to detect predominantly mono- and dicarboxylic acids, which are major oxidation products of biogenic terpenes. The MOVI-APCI-IT/MS instrument was used for the analysis of laboratory-generated secondary organic aerosol (SOA), which was generated by ozonolysis of alpha-pinene in a 100 L continuous-flow reactor under dark and dry conditions. The combination of the MOVI with an APCI-IT/MS improved the detection Limits for small dicarboxylic acids, such as pinic acid, compared to online measurements by APCI-IT/MS. The Limits of detection and quantification for pinic acid were determined by external calibration to 4.4 ng and 13.2 ng, respectively. During a field campaign in the southern Rocky Mountains (USA) in summer 2011 (BEACHON-RoMBAS), the MOVI-APCI-IT/MS was applied for the analysis of ambient organic aerosols and the quantification of individual biogenic SOA marker compounds. Based on a measurement frequency of approximately 5 h, a diurnal cycle for pinic acid in the sampled aerosol particles was found with maximum concentrations at night (median: 10.1 ngm(-3)) and minimum concentrations during the day (median: 8.2 ng m(-3)), which is likely due to the partitioning behavior of pinic acid and the changing phase state of the organic aerosol particles with changing relative humidity. PMID:24881453

  5. Screening and quantification of pesticide residues in fruits and vegetables making use of gas chromatography-quadrupole time-of-flight mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Cervera, M I; Portolés, T; López, F J; Beltrán, J; Hernández, F

    2014-11-01

    An atmospheric pressure chemical ionization source has been used to enhance the potential of gas chromatography coupled with quadrupole time-of-flight (QTOF) mass spectrometry (MS) for screening and quantification purposes in pesticide residue analysis. A screening method developed in our laboratory for around 130 pesticides has been applied to fruit and vegetable samples, including strawberries, oranges, apples, carrots, lettuces, courgettes, red peppers, and tomatoes. Samples were analyzed together with quality control samples (at 0.05 mg/kg) for each matrix and for matrix-matched calibration standards. The screening strategy consisted in first rapid searching and detection, and then a refined identification step using the QTOF capabilities (MS(E) and accurate mass). Identification was based on the presence of one characteristic m/z ion (Q) obtained with the low collision energy function and at least one fragment ion (q) obtained with the high collision energy function, both with mass errors of less than 5 ppm, and an ion intensity ratio (q/Q) within the tolerances permitted. Following this strategy, 15 of 130 pesticides were identified in the samples. Afterwards, the quantitation capabilities were tested by performing a quantitative validation for those pesticides detected in the samples. To this aim, five matrices were selected (orange, apple, tomato, lettuce, and carrot) and spiked at two concentrations (0.01 and 0.1 mg/kg), and quantification was done using matrix-matched calibration standards (relative responses versus triphenyl phosphate used as an internal standard). Acceptable average recoveries and relative standard deviations were obtained for many but not all pesticide-matrix combinations. These figures allowed us to perform a retrospective quantification of positives found in the screening without the need for additional analysis. Taking advantage of the accurate-mass full-spectrum data provided by QTOF MS, we searched for a higher number of compounds (up to 416 pesticides) in a second stage by performing extra data processing without any new sample injection. Several more pesticides were detected, confirmed, and/or tentatively identified when the reference standard was unavailable, illustrating in this way the potential of gas chromatography-QTOF MS to detect pesticides in addition to the ones targeted in quantitative analysis of pesticides in food matrices. PMID:24828980

  6. Evaluation of gas chromatography-atmospheric pressure chemical ionization-mass spectrometry as an alternative to gas chromatography-electron ionization-mass spectrometry: avocado fruit as example.

    PubMed

    Hurtado-Fernández, Elena; Pacchiarotta, Tiziana; Longueira-Suárez, Enrique; Mayboroda, Oleg A; Fernández-Gutiérrez, Alberto; Carrasco-Pancorbo, Alegría

    2013-10-25

    Although GC-APCI-MS was developed more than 40 years ago this coupling is still far from being a routine technique. One of the reasons explaining the limited use of GC-APCI so far is the lack of spectral database which facilitates the identification of the compounds under study. The first application of a very recently developed GC-APCI database to identify as many compounds as possible in a complex matrix such as avocado fruit is presented here. The results achieved by using this database has been checked against those obtained using traditional GC-EI-MS and a comparison of the MS signals observed in both ionization sources has been carried out. 100 compounds belonging to different chemical families were identified in the matrix under study. Considering the results of this study, the wide range of application (in terms of polarity and size of analytes) and the robustness of APCI as interface, the high quality of TOF spectra, and our library as a publicly available resource, GC-APCI-TOF MS is definitively a valuable addition to the "metabolomics toolbox". PMID:24054422

  7. The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system.

    PubMed

    Kudryavtsev, Andrey S; Makas, Alexey L; Troshkov, Mikhail L; Grachev, Mikhail ?; Pod'yachev, Sergey P

    2014-06-01

    A method for fast simultaneous on-site determination of methyl mercaptan and dimethyl sulfide in air was developed. The target compounds were actively collected on silica gel, followed by direct flash thermal desorption, fast separation on a short chromatographic column and detection by means of mass spectrometer with atmospheric pressure chemical ionization. During the sampling of ambient air, water vapor was removed with a Nafion selective membrane. A compact mass spectrometer prototype, which was designed earlier at Trofimuk Institute of Petroleum Geology and Geophysics, was used. The minimization of gas load of the atmospheric pressure ion source allowed reducing the power requirements and size of the vacuum system and increasing its ruggedness. The measurement cycle is about 3 min. Detection limits in a 0.6 L sample are 1 ppb for methyl mercaptan and 0.2 ppb for dimethyl sulfide. PMID:24725876

  8. The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

    PubMed

    Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

    2014-11-01

    A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M?+?77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI. PMID:25248413

  9. Triacylglycerol Analysis of Potential Margarine Base Stocks by High-Performance Liquid Chromatography with Atmospheric Pressure Chemical Ionization Mass Spectrometry and Flame Ionization Detection

    Microsoft Academic Search

    W. Craig Byrdwell; William E. Neff; Gary R. List

    2001-01-01

    Several margarine base stock candidates have previously been prepared for the purpose of finding better, more oxidatively stable food components: high-saturate vegetable oils, randomized vegetable oils, vegetable oil-hard stock blends, and interesterified vegetable oil-hard stock blends. Here are reported the triacylglycerol compositions of these products, determined using reverse-phase high- performance liquid chromatography (HPLC) coupled with a flame ionization detector or

  10. Liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric analysis of opiates and metabolites in rat urine after inhalation of opium.

    PubMed

    Kikura-Hanajiri, R; Kaniwa, N; Ishibashi, M; Makino, Y; Kojima, S

    2003-06-01

    To examine the urinary excretion of opiates and their metabolites following inhalation exposure of rats to opium, analytical procedures for the simultaneous determination of the compounds in opium, the vapor derived by the volatilization of opium and the urine of rats exposed to the opium vapor were developed using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). Seven compounds were determined in the opium, namely morphine, codeine, thebaine, noscapine, papaverine, meconic acid and meconin. All seven were extracted with 2.5% acetic acid solution and subjected to LC-APCI-MS analysis. The separation was performed on an ODS column in acetonitrile-50 mM ammonium formate buffer (pH 3.0) using a linear gradient program and quantitative analysis was carried out in the selected ion monitoring mode ([M+H](+)). For the analysis of the volatilization of opium, the opium (1 g) was added to a glass pipe, which was then heated at 300 degrees C for 20 min. Negative pressure (air flow-rate; 300 ml/min) was used to draw the vapor through a series of glass wool and methanol traps. The total amount of each compound in the vapor was estimated by measurement of the compounds trapped in the glass wool and methanol. Wister rats (n=3) were exposed to the vapor derived from the volatilization system and the urinary amounts (0-72 h) of the six opiates and metabolites including morphine-3-grucronide (M3G) and morphine-6-grucronide (M6G) were measured after solid-phase extraction. The calibration curves for those compounds in the rat urine were linear over the concentration range 10-500 ng/ml. The recoveries for each analyte from the rat urine sample spiked with standard solution were generally greater than 80%, and the relative standard deviation for the analytical procedure was less than 8% with the exception of meconin. After inhalation exposure of rats to opium, M3G (5.45-14.38 micro g), morphine (2.27-4.65 micro g), meconin (0.54-1.85 micro g), codeine (0.54-1.85 micro g), noscapine (0.34-0.40 micro g) and papaverine (0.01-0.04 micro g) were detected in the urine over 72 h. However, only trace levels of thebaine were observed despite it being one of the major alkaloids found in the opium. On the other hand, a relatively large amount of meconin was detected in the vapor and the urine as compared with the opium. It is suggested that the presence of meconin in biological fluids could be indicative of opium ingestion by inhalation. PMID:12726852

  11. Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization in Transmission Geometry

    E-print Network

    Vertes, Akos

    Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization in Transmission Geometry Marsha C, Washington, D.C. 20375 In both atmospheric pressure matrix-assisted laser de- sorption/ionization (AP MALDI a significant impediment. Atmospheric pressure (AP) MALDI promises to eliminate the need for this step.1

  12. Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool in laser evaporation methods

    E-print Network

    Vertes, Akos

    Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool introduced analytical method, atmospheric pressure matrix-assisted laser desorption ionization (AP- MALDI write; Atmospheric pressure MALDI; Laser evaporation; Plume diagnostics 1. Introduction Diagnostics

  13. Fragmentation energy index for universalization of fragmentation energy in ion trap mass spectrometers for the analysis of chemical weapon convention related chemicals by atmospheric pressure ionization-tandem mass spectrometry analysis.

    PubMed

    Palit, Meehir; Mallard, Gary

    2009-04-01

    The use of mass spectra generated at 70 eV in electron ionization (EI) as a universal standard for EI has helped in the generation of searchable library databases and had a profound influence on the analytical applications of gas chromatography/mass spectrometry (GC/MS), similarly for liquid chromatography tandem mass spectrometry (LC-MS/MS), suggesting a novel method to normalize the collisional energy for the universalization of fragmentation energy for the analysis of Chemical Weapon Convention (CWC)-related chemicals by atmospheric pressure ionization-tandem mass spectrometry (API-MS(n)) using three-dimensional (3D) ion trap instruments. For normalizing fragmentation energy a "fragmentation energy index" (FEI) is proposed which is an arbitrary scale based on the fact of specific MS/MS fragmentation obtained at different collisional energies for the reference chemicals which are not CWC scheduled compounds. FEI 6 for the generation of an MS(n) library-searchable mass spectral database is recommended. PMID:19331429

  14. An atmospheric pressure ion lens to improve electrospray ionization at low solution ow-rates

    E-print Network

    Chen, David D.Y.

    An atmospheric pressure ion lens to improve electrospray ionization at low solution ¯ow by the addition of an atmospheric pressure ion lens near the tip of the tapered sprayer. The magnitude, but no discussion was given as to whether it increased the ion signals. Franzen used an atmospheric pressure ring

  15. Application of an Air Ionization Device Using an Atmospheric Pressure Corona Discharge Process for Water Purification

    Microsoft Academic Search

    Jens Wohlers; In-Ock Koh; Wolfram Thiemann; Wolfgang Rotard

    2009-01-01

    Pesticides presently being discharged into the aquatic environment are not only toxic but also only partially biodegradable,\\u000a they are not easily removed by conventional water treatment plants. Air ionization devices using an atmospheric pressure corona\\u000a discharge process show great promise in improving degradation of chemical and biological contaminants in water purification\\u000a plants. In order to assess the effectiveness of this

  16. Development of an Atmospheric Pressure Ionization Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A commercial atmospheric pressure ionization mass spectrometer (APIMS) was purchased from EXTREL Mass Spectrometry, Inc. (Pittsburgh, PA). Our research objectives were to adapt this instrument and develop techniques for real-time determinations of the concentrations of trace species in the atmosphere. The prototype instrument is capable of making high frequency measurements with no sample preconcentrations. Isotopically labeled standards are used as an internal standard to obtain high precision and to compensate for changes in instrument sensitivity and analyte losses in the sampling manifold as described by Bandy and coworkers. The prototype instrument is capable of being deployed on NASA C130, Electra, P3, and DC8 aircraft. After purchasing and taking delivery by June 1994, we assembled the mass spectrometer, data acquisition, and manifold flow control instrumentation in electronic racks and performed tests.

  17. Comparison of electrospray ionization and atmospheric pressure chemical ionization for multi-residue analysis of biocides, UV-filters and benzothiazoles in aqueous matrices and activated sludge by liquid chromatography-tandem mass spectrometry.

    PubMed

    Wick, Arne; Fink, Guido; Ternes, Thomas A

    2010-04-01

    This paper describes the development of a multi-residue method for the determination of 36 emerging organic pollutants (26 biocides, 5 UV-filters and 5 benzothiazoles) in raw and treated wastewater, activated sludge and surface water using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The target analytes were enriched from water samples adjusted to pH 6 by solid-phase extraction (SPE) on Oasis HLB 200mg cartridges and eluted with a mixture of methanol and acetone (60/40, v/v). Extraction of freeze-dried sludge samples was accomplished by pressurized liquid extraction (PLE) using a mixture of methanol and water (50/50, v/v) as extraction solvent followed by SPE. LC-tandem MS detection was compared using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) in positive and negative ionization mode. ESI exhibited strong ion suppression for most target analytes, while APCI was generally less susceptible to ion suppression but partially leading to ion enhancement of up to a factor of 10. In general, matrix effects could be compensated using stable isotope-labeled surrogate standards, indicated by relative recoveries ranging from 70% to 130%. In wastewater, activated sludge and surface water up to 33 analytes were detected. Maximum concentrations up to 5.1 and 3.9mugL(-1) were found in raw wastewater for the water-soluble UV-filters benzophenone-4 (BZP-4) and phenylbenz-imidazole sulfonic acid (PBSA), respectively. For the first time, the anti-dandruff climbazole was detected in raw wastewater and in activated sludge with concentrations as high as 1.4 microg L(-1) and 1.2 microg gTSS(-1), respectively. Activated sludge is obviously a sink for four benzothiazoles and two isothiazolones, as concentrations were detected in activated sludge between 120 ng gTSS(-1) (2-n-octyl-4-isothiazolin-3-one, OIT) to 330 ng gTSS(-1) (benzothiazole-2-sulfonic acid, BTSA). PMID:20202641

  18. Characterization of HOCl using atmospheric pressure ionization mass spectrometry

    SciTech Connect

    Caldwell, T.E.; Foster, K.L.; Benter, T.; Langer, S.; Hemminger, J.C.; Finlayson-Pitts, B.J.

    1999-10-14

    HOCl is an important intermediate in stratospheric and tropospheric chemistry. Although it can be readily measured in laboratory systems at low pressures ({le}20 Torr) using conventional electron impact ionization mass spectrometry, there is a need for a measurement technique that can operate at higher pressures, up to 1 atm in air. One such technique seeing increasing use is atmospheric pressure ionization mass spectrometry (API-MS). The authors report here studies of the API-MS of {approximately}0.5--50 ppm HOCl at a total pressure of 1 atm and room temperature. Major peaks from the ion-adducts with Cl{sup {minus}} and OCI{sup {minus}} were observed. The Br{sup {minus}} adduct of HOCl can also be generated using bromoform in the discharge region of the ion source. At the lower range of HOCl concentrations studied in air, the O{sub 2}{sup {minus}} adduct and small parent peaks assigned to HOCl{sup {minus}} were observed. The species present as minor impurities in the HOCl source (Cl{sub 2}, Cl{sub 2}O and HCl) can be readily distinguished through identification of the parent ion for Cl{sub 2}, or as their adducts with Cl{sup {minus}} and Br{sup {minus}} for Cl{sub 2}O and HCI. The identification of HOCl was confirmed using electron impact ionization time-of-flight mass spectrometry (El-MS). HOCl was quantified using EI-MS to measure the Cl{sub 2} generated when the HOCl reacted heterogeneously on a water-ice/HCl surface and independently by photolysis of the HOCl to generate atomic chlorine, which was trapped using propene and measured as chloroacetone. The implications for the use of API-MS for measuring HOCl in laboratory systems and in ambient air are discussed.

  19. Atmospheric pressure ionization and gas phase ion mobility studies of isomeric dihalogenated benzenes using different ionization techniques

    NASA Astrophysics Data System (ADS)

    Borsdorf, H.; Nazarov, E. G.; Eiceman, G. A.

    2004-03-01

    Ion mobility spectrometry (IMS) featuring different ionization techniques was used to analyze isomeric ortho-, meta- and para-dihalogenated benzenes in order to assess how structural features affect ion formation and drift behavior. The structure of the product ions formed was investigated by atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and IMS-MS coupling. Photoionization provided [M]+ ions for chlorinated and fluorinated compounds while bromine was cleaved from isomers of dibromobenzene and bromofluorobenzene. This ionization technique does not permit the different isomers to be distinguished. Comparable ions and additional clustered ions were obtained using 63Ni ionization. Depending on the chemical constitution, different clustered ions were observed in ion mobility spectra for the separate isomers of dichlorobenzene and dibromobenzene. Corona discharge ionization permits the most sensitive detection of dihalogenated compounds. Only clustered product ions were obtained. Corona discharge ionization enables the classification of different structural isomers of dichlorobenzene, dibromobenzene and bromofluorobenzene.

  20. Screening for library-assisted identification and fully validated quantification of 22 beta-blockers in blood plasma by liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Maurer, Hans H; Tenberken, Oliver; Kratzsch, Carsten; Weber, Armin A; Peters, Frank T

    2004-11-26

    A liquid chromatographic-mass spectrometric assay with atmospheric pressure chemical ionization (LC-APCI-MS) is presented for screening for, library-assisted identification (both in scan mode) and quantification (selected-ion mode) of the beta-blockers acebutolol, diacetolol, alprenolol, atenolol, betaxolol, bisoprolol, bupranolol, carazolol, carteolol, carvedilol, celiprolol, esmolol, labetalol, metoprolol, nadolol, nebivolol, oxprenolol, penbutolol, propranolol, sotalol, talinolol and timolol in blood plasma after mixed-mode (HCX) solid-phase extraction (SPE) and separation by reverse-phase liquid chromatography with gradient elution. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples allowing confirmation of diagnosis of overdose situations as well as monitoring of patients' compliance. PMID:15595665

  1. Direct and simultaneous quantitation of 5-aminolaevulinic acid and porphobilinogen in human serum or plasma by hydrophilic interaction liquid chromatography-atmospheric pressure chemical ionization/tandem mass spectrometry.

    PubMed

    Benton, Christopher M; Couchman, Lewis; Marsden, Joanne T; Rees, David C; Moniz, Caje; Lim, Chang Kee

    2013-02-01

    Serum/plasma concentrations of 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG) are elevated in patients with acute hepatic porphyrias, especially during acute attacks. Current assays require lengthy sample pre-treatment and derivatization steps. We report here a rapid, sensitive and specific hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the direct and simultaneous quantitation of ALA and PBG in serum or plasma following simple protein precipitation with acetonitrile and centrifugation prior to injection. ALA and PBG were detected using selected reaction monitoring mode, following positive atmospheric pressure chemical ionization. Calibration was linear from 0.05 to 50 µmol/L for ALA and PBG. For both analytes, imprecision (relative standard deviation) was <13% and accuracy (percentage nominal concentrations) was between 92 and 107%. The method was successfully applied to the measurement of ALA and PBG in serum or plasma samples for the screening, biochemical diagnosis and treatment monitoring of patients with acute hepatic porphyrias. PMID:23180457

  2. Development and validation of a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry method for simultaneous analysis of ten amphetamine-, methamphetamine- and 3,4-methylenedioxymethamphetamine-related (MDMA) analytes in human meconium

    PubMed Central

    Kelly, Tamsin; Gray, Teresa R.; Huestis, Marilyn A.

    2008-01-01

    A liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (LC-APCI-MS/MS) method for quantification of ten amphetamine-related analytes in 1 g meconium is presented. Specimen preparation included homogenization and solid phase extraction. Two multiple reaction monitoring transitions were monitored per analyte. Ten and 1 µL injection volumes permitted quantification up to 10,000 ng/g, with sufficient sensitivity to quantify minor metabolites. Lower limits of quantification ranged from 1.25 to 40 ng/g. Precision was less than 14.2%, with accuracy between 79 – 115%. Meconium from a methamphetamine-exposed neonate was analyzed. Metabolites p-hydroxymethamphetamine, norephedrine and 4-hydroxy-3-methoxymethamphetamine were identified in meconium for the first time. PMID:18424195

  3. Plasma Ion Sources for Atmospheric Pressure Ionization Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Zhao, Jian-Guo

    1994-01-01

    Atmospheric pressure ionization (API) sources using direct-current (DC) and radio-frequency (RF) plasma have been developed in this thesis work. These ion sources can provide stable discharge currents of ~ 1 mA, 2-3 orders of magnitude larger than that of the corona discharge, a widely used API source. The plasmas can be generated and maintained in 1 atm of various buffer gases by applying -500 to -1000 V (DC plasma) or 1-15 W with a frequency of 165 kHz (RF plasma) on the needle electrode. These ion sources have been used with liquid injection to detect various organic compounds of pharmaceutical, biotechnological and environmental interest. Key features of these ion sources include soft ionization with the protonated molecule as the largest peak, and superb sensitivity with detection limits in the low picogram or femtomole range and a linear dynamic range over ~4 orders of magnitude. The RF plasma has advantages over the DC plasma in its ability to operate in various buffer gases and to produce a more stable plasma. Factors influencing the performance of the ion sources have been studied, including RF power level, liquid flow rate, chamber temperature, solvent composition, and voltage affecting the collision induced dissociation (CID). Ionization of hydrocarbons by the RF plasma API source was also studied. Soft ionization is generally produced. To obtain high sensitivity, the ion source must be very dry and the needle-to-orifice distance must be small. Nitric oxide was used to enhance the sensitivity. The RF plasma source was then used for the analysis of hydrocarbons in auto emissions. Comparisons between the corona discharge and the RF plasma have been made in terms of discharge current, ion residence time, and the ion source model. The RF plasma source provides larger linear dynamic range and higher sensitivity than the corona discharge, due to its much larger discharge current. The RF plasma was also observed to provide longer ion residence times and was not limited by space-charge effect as in the corona source.

  4. The role of physical and chemical properties of Pd nanostructured materials immobilized on inorganic carriers on ion formation in atmospheric pressure laser desorption/ionization mass spectrometry.

    PubMed

    Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

    2014-06-01

    Fundamental parameters influencing the ion-producing efficiency of palladium nanostructures (nanoparticles [Pd-NP], nanoflowers, nanofilms) during laser irradiation were studied in this paper. The nanostructures were immobilized on the surface of different solid inorganic carrier materials (porous and mono-crystalline silicon, anodic porous aluminum oxide, glass and polished steel) by using classical galvanic deposition, electroless local deposition and sputtering. It was the goal of this study to investigate the influence of both the nanoparticular layer as well as the carrier material on ion production for selected analyte molecules. Our experiments demonstrated that the dimensions of the synthesized nanostructures, the thickness of the active layers, surface disorders, thermal conductivity and physically or chemically adsorbed water influenced signal intensities of analyte ions during surface-assisted laser desorption/ionization (SALDI) while no effects such as plasmon resonance, photoelectric effect or catalytic activity were expected to occur. Excellent LDI abilities were seen for Pd-NPs immobilized on steel, while Pd nanoflowers on porous silicon exhibited several disadvantages; viz, strong memory effects, dependency of the analytical signal on amount of physically and chemically adsorbed water inside porous carrier, reduced SALDI activity from unstable connections between Pd and semiconductor material, decrease of the melting point of pure silicon after Pd immobilization and resulting strong laser ablation of metal/semiconductor complex, as well as significantly changed surface morphology after laser irradiation. The analytical performance of Pd-NP/steel was further improved by applying a hydrophobic coating to the steel surface before galvanic deposition. This procedure increased the distance between Pd-NPs, thus reducing thermal stress upon LDI; it simultaneously decreased spot sizes of deposited sample solutions. PMID:24913399

  5. Schinus terebinthifolius scale-up countercurrent chromatography (Part I): High performance countercurrent chromatography fractionation of triterpene acids with off-line detection using atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Vieira, Mariana Neves; Costa, Fernanda das Neves; Leitão, Gilda Guimarães; Garrard, Ian; Hewitson, Peter; Ignatova, Svetlana; Winterhalter, Peter; Jerz, Gerold

    2015-04-10

    'Countercurrent chromatography' (CCC) is an ideal technique for the recovery, purification and isolation of bioactive natural products, due to the liquid nature of the stationary phase, process predictability and the possibility of scale-up from analytical to preparative scale. In this work, a method developed for the fractionation of Schinus terebinthifolius Raddi berries dichloromethane extract was thoroughly optimized to achieve maximal throughput with minimal solvent and time consumption per gram of processed crude extract, using analytical, semi-preparative and preparative 'high performance countercurrent chromatography' (HPCCC) instruments. The method using the biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (6:1:6:1, v/v/v/v) was volumetrically scaled up to increase sample throughput up to 120 times, while maintaining separation efficiency and time. As a fast and specific detection alternative, the fractions collected from the CCC-separations were injected to an 'atmospheric pressure chemical ionization mass-spectrometer' (APCI-MS/MS) and reconstituted molecular weight MS-chromatograms of the APCI-ionizable compounds from S. terebinthifolius were obtained. This procedure led to the direct isolation of tirucallane type triterpenes such as masticadienonic and 3?-masticadienolic acids. Also oleanonic and moronic acids have been identified for the first time in the species. In summary, this approach can be used for other CCC scale-up processes, enabling MS-target-guided isolation procedures. PMID:25757818

  6. Real-time air monitoring of mustard gas and Lewisite 1 by detecting their in-line reaction products by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow ion introduction.

    PubMed

    Okumura, Akihiko; Takada, Yasuaki; Watanabe, Susumu; Hashimoto, Hiroaki; Ezawa, Naoya; Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Kondo, Tomohide; Nagashima, Hisayuki; Nagoya, Tomoki

    2015-01-20

    A new method enabling sensitive real-time air monitoring of highly reactive chemical warfare agents, namely, mustard gas (HD) and Lewisite 1 (L1), by detecting ions of their in-line reaction products instead of intact agents, is proposed. The method is based on corona discharge-initiated atmospheric pressure chemical ionization coupled with ion trap tandem mass spectrometry (MS(n)) via counterflow ion introduction. Therefore, it allows for highly sensitive and specific real-time detection of a broad range of airborne compounds. In-line chemical reactions, ionization reactions, and ion fragmentations of these agents were investigated. Mustard gas is oxygenated in small quantity by reactive oxygen species generated in the corona discharge. With increasing air humidity, the MS(2) signal intensity of protonated molecules of mono-oxygenated HD decreases but exceeds that of dominantly existing intact HD. This result can be explained in view of proton affinity. Lewisite 1 is hydrolyzed and oxidized. As the humidity increases from zero, the signal of the final product, namely, didechlorinated, dihydroxylated, and mono-oxygenated L1, quickly increases and reaches a plateau, giving the highest MS(2) and MS(3) signals among those of L1 and its reaction products. The addition of minimal moisture gives the highest signal intensity, even under low humidity. The method was demonstrated to provide sufficient analytical performance to meet the requirements concerning hygienic management and counter-terrorism. It will be the first practical method, in view of sensitivity and specificity, for real-time air monitoring of HD and L1 without sample pretreatment. PMID:25553788

  7. Quantitation of spectinomycin residues in bovine tissues by ion-exchange high-performance liquid chromatography with post-column derivatization and confirmation by reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    Hornish, R E; Wiest, J R

    1998-07-01

    Determinative and confirmatory methods of analysis for spectinomycin residue in bovine kidney, liver, muscle and fat have been developed. The determinative method is a single-column HPLC ion-exchange procedure that incorporates a two-step post-column oxidation of the secondary amines to primary amines followed by derivatization with o-phthalaldehyde. The method was validated in all tissues to a low-end concentration of 0.10 micrograms/g (limit of quantitation) and to a high-end of 10 micrograms/g for kidney, which is the rate-limiting tissue for residues of spectinomycin. The recovery of spectinomycin from all tissues was > 80% and the variability (R.S.D.) was generally < 10%. For liver, an alternative reversed-phase HPLC separation was required for incurred-residue samples. The confirmatory method employed an atmospheric pressure chemical ionization-MS-MS approach utilizing a rapid reversed-phase HPLC system with a mobile phase of methanol and 1% acetic acid. The protonated molecular ion for spectinomycin at m/z 333 produced four diagnostic reaction-product ions at 98, 116, 158 and 189 for confirmation. The method was validated to a lower limit of confirmation of 0.10 micrograms/g. PMID:9691313

  8. Pressurized liquid extraction and dispersive liquid-liquid microextraction for determination of tocopherols and tocotrienols in plant foods by liquid chromatography with fluorescence and atmospheric pressure chemical ionization-mass spectrometry detection.

    PubMed

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Pastor-Belda, Marta; Hernández-Córdoba, Manuel

    2014-02-01

    Pressurized liquid extraction (PLE) and dispersive liquid-liquid microextraction (DLLME) were used to isolate and preconcentrate tocopherols and tocotrienols from plant foods. The Taguchi experimental method was used to optimize the six factors (three levels for each factor), affecting DLLME, namely: carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The influencing parameters selected were 2 mL of methanol:isopropanol (1:1) (disperser solvent), 150 µL carbon tetrachloride (extraction solvent) and 10 mL aqueous solution. The organic phase was injected into reversed-phase liquid chromatography (LC) with an isocratic mobile phase composed of an 85:15 (v/v) methanol:water mixture and a pentafluorophenyl stationary phase. Detection was carried out using both fluorescence and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) in negative ion mode. Quantification was carried out by the standard addition method. Detection limits were in the range 0.2-0.3 ng mL(-1) for the vitamers with base-line resolution. The recoveries obtained using the optimized DLLME were in the 90-108% range, with RSDs lower than 6.7%. The APCI-MS spectra, in combination with fluorescence spectra, permitted the correct identification of compounds in the vegetable and fruit samples. The method was validated according to international guidelines and using two certified reference materials. PMID:24401390

  9. Preparative mass-spectrometry profiling of bioactive metabolites in Saudi-Arabian propolis fractionated by high-speed countercurrent chromatography and off-line atmospheric pressure chemical ionization mass-spectrometry injection.

    PubMed

    Jerz, Gerold; Elnakady, Yasser A; Braun, André; Jäckel, Kristin; Sasse, Florenz; Al Ghamdi, Ahmad A; Omar, Mohamed O M; Winterhalter, Peter

    2014-06-20

    Propolis is a glue material collected by honeybees which is used to seal cracks in beehives and to protect the bee population from infections. Propolis resins have a long history in medicinal use as a natural remedy. The multiple biological properties are related to variations in their chemical compositions. Geographical settings and availability of plant sources are important factors for the occurrence of specific natural products in propolis. A propolis ethylacetate extract (800mg) from Saudi Arabia (Al-Baha region) was separated by preparative scale high-speed countercurrent chromatography (HSCCC) using a non-aqueous solvent system n-hexane-ACN (1:1, v/v). For multiple metabolite detection, the resulting HSCCC-fractions were sequentially injected off-line into an atmospheric pressure chemical ionization mass-spectrometry (APCI-MS/MS) device, and a reconstituted mass spectrometry profile of the preparative run was visualized by selected ion traces. Best ion-intensities for detected compounds were obtained in the negative APCI mode and monitored occurring co-elution effects. HSCCC and successive purification steps resulted in the isolation and characterization of various bioactive natural products such as (12E)- and (12Z)-communic acid, sandaracopimaric acid, (+)-ferruginol, (+)-totarol, and 3?-acetoxy-19(29)-taraxasten-20a-ol using EI-, APCI-MS and 1D/2D-NMR. Cycloartenol-derivatives and triterpene acetates were isolated in mixtures and elucidated by EI-MS and 1D-NMR. Free fatty acids, and two labdane fatty acid esters were identified by APCI-MS/MS. In total 19 metabolites have been identified. The novel combination of HSCCC fractionation, and APCI-MS-target-guided molecular mass profiling improve efficiency of lead-structure identification. PMID:24831423

  10. Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass

    E-print Network

    Vertes, Akos

    Laser Ablation Electrospray Ionization for Atmospheric Pressure, in Vivo, and Imaging Mass changes in organisms with high specificity. Here we report on a novel combination of infrared laser ablation with electrospray ionization (LAESI) as an ambient ion source for mass spectrometry. As a result

  11. Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry

    E-print Network

    Vertes, Akos

    Chapter 9 Laser Ablation Electrospray Ionization for Atmospheric Pressure Molecular Imaging Mass Spectrometry Peter Nemes and Akos Vertes Abstract Laser ablation electrospray ionization (LAESI) is a novel-IR) MALDI (3), laser ablation S.S. Rubakhin, J.V. Sweedler (eds.), Mass Spectrometry Imaging, Methods

  12. Screening, library-assisted identification and validated quantification of 23 benzodiazepines, flumazenil, zaleplone, zolpidem and zopiclone in plasma by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Kratzsch, Carsten; Tenberken, Oliver; Peters, Frank T; Weber, Armin A; Kraemer, Thomas; Maurer, Hans H

    2004-08-01

    A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (LC/APCI-MS) is presented for fast and reliable screening and identification and also for precise and sensitive quantification in plasma of the 23 benzodiazepines alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, diazepam, flunitrazepam, flurazepam, desalkylflurazepam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, prazepam, temazepam and tetrazepam, triazolam, their antagonist flumazenil and the benzodiazepine BZ1 (omega 1) receptor agonists zaleplone, zolpidem and zopiclone. It allows confirmation of the diagnosis of an overdose situation and monitoring of psychiatric patients' compliance. The analytes were isolated from plasma using liquid-liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' LC/MS library, the analytes were quantified in the selected-ion monitoring mode. The quantification assay was fully validated. It was found to be selective proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes, except bromazepam. The corresponding reference levels the assay's accuracy and precision data for all studied substances are listed. The accuracy and precision data were within the required limits with the exception of those for bromazepam. The analytes were stable in frozen plasma for at least 1 month. The validated assay was successfully applied to several authentic plasma samples from patients treated or intoxicated with various benzodiazepines or with zaleplone, zolpidem or zopiclone. It has proven to be appropriate for the isolation, separation, screening, identification and quantification of the drugs mentioned above in plasma for clinical toxicology, e.g. in cases of poisoning, and forensic toxicology, e.g. in cases of driving under the influence of drugs. PMID:15329838

  13. Dispersive liquid-liquid microextraction for the determination of vitamins D and K in foods by liquid chromatography with diode-array and atmospheric pressure chemical ionization-mass spectrometry detection.

    PubMed

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

    2013-10-15

    A simple and rapid method was developed using reversed-phase liquid chromatography (LC) with both diode array (DAD) and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of the vitamins ergocalciferol (D2), cholecalciferol (D3), phylloquinone (K1), menaquinone-4 (K2) and a synthetic form of vitamin K, menadione (K3). The Taguchi experimental method, an orthogonal array design (OAD), was used to optimize an efficient and clean preconcentration step based on dispersive liquid-liquid microextraction (DLLME). A factorial design was applied with six factors and three levels for each factor, namely, carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The DLLME optimized procedure consisted of rapidly injecting 3 mL of acetonitrile (disperser solvent) containing 150 µL carbon tetrachloride (extraction solvent) into the aqueous sample, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was evaporated with nitrogen, reconstituted with 50 µL of acetonitrile, and injected. The LC analyses were carried out using a mobile phase composed of acetonitrile, 2-propanol and water, under gradient elution. Quantification was carried out by the standard additions method. The APCI-MS spectra, in combination with UV spectra, permitted the correct identification of compounds in the food samples. The method was validated according to international guidelines and using a certified reference material. The validated method was applied for the analysis of vitamins D and K in infant foods and several green vegetables. There was little variability in the forms of vitamin K present in vegetables, with the most abundant vitamer in all the samples being phylloquinone, while menadione could not be detected. Conversely, cholecalciferol, which is present in food of animal origin, was the main form in infant foods, while ergocalciferol was not detected. PMID:24054666

  14. An improved high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry method for determination of chlorophylls and their derivatives in freeze-dried and hot-air-dried Rhinacanthus nasutus (L.) Kurz.

    PubMed

    Kao, Tsai Hua; Chen, Chia Ju; Chen, Bing Huei

    2011-10-30

    Rhinacanthus nasutus (L.) Kurz, a traditional Chinese herb possessing antioxidant and anti-cancer activities, has been reported to contain functional components like carotenoids and chlorophylls. However, the variety and amount of chlorophylls remain uncertain. The objectives of this study were to develop a high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry (HPLC-DAD-APCI-MS) method for determination of chlorophylls and their derivatives in hot-air-dried and freeze-dried R. nasutus. An Agilent Eclipse XDB-C18 column and a gradient mobile phase composed of methanol/N,N-dimethylformamide (97:3, v/v), acetonitrile and acetone were employed to separate internal standard zinc-phthalocyanine plus 12 cholorophylls and their derivatives within 21 min, including chlorophyll a, chlorophyll a', hydroxychlorophyll a, 15-OH-lactone chlorophyll a, chlorophyll b, chlorophyll b', hydroxychlorophyll b, pheophytin a, pheophytin a', hydroxypheophytin a, hydroxypheophytin a' and pheophytin b in hot-air-dried R. nasutus with flow rate at 1 mL/min and detection at 660 nm. But, in freeze-dried R. nasutus, only 4 chlorophylls and their derivatives, including chlorophyll a, chlorophyll a', chlorophyll b and pheophytin a were detected. Zinc-phthalocyanine was found to be an appropriate internal standard to quantify all the chlorophyll compounds. After quantification by HPLC-DAD, both chlorophyll a and pheophytin a were the most abundant in hot-air-dried R. nasutus, while in freeze-dried R. nasutus, chlorophyll a and chlorophyll b dominated. PMID:22063550

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

    PubMed

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

    2014-11-18

    We present laser desorption atmospheric pressure photochemical ionization mass spectrometry (LD/APPCI MS) for rapid throughput analysis of complex organic mixtures, without the need for matrix, electric discharge, secondary electrospray, or solvents/vaporizers. Analytes dried on a microscope slide are vaporized in transmission geometry by a laser beam aligned with the atmospheric pressure inlet of the mass spectrometer. The laser beam initiates a cascade of reactions in the region between the glass slide and MS inlet, leading to generation of reagent ions for chemical ionization of vaporized analyte. Positive analyte ions are generated predominantly by proton transfer, charge exchange, and hydride abstraction, whereas negative ions are generated by electron capture or proton transfer reactions, enabling simultaneous analysis of saturated, unsaturated, and heteroatom-containing hydrocarbons. The absence of matrix interference renders LD/APPCI MS particularly useful for analysis of small molecules (<2000 Da) such as those present in petroleum crude oil and petroleum deposits. [M + H](+) and M(+•) dominate the positive-ion mass spectra for olefins and polyaromatic hydrocarbons, whereas saturated hydrocarbons are observed mainly as [M - H](+) and/or M(+•). Heteroatom-containing hydrocarbons are observed predominantly as [M + H](+). [M - H](-) and M(-•) are the dominant negative ions observed for analytes of lower gas-phase basicity or higher electron affinity than O2. The source was coupled with a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer (FTICR MS) to resolve and identify thousands of peaks from Athabasca bitumen heavy vacuum gas oil distillates (400-425 and 500-538 °C), enabling simultaneous characterization of their polar and nonpolar composition. We also applied LD/APPCI FTICR MS for rapid analysis of sodium and calcium naphthenate deposits with little to no sample pretreatment to provide mass spectral fingerprints that enable reliable compositional characterization. PMID:25347814

  16. Determination of nivalenol and deoxynivalenol in wheat using liquid chromatography–mass spectrometry with negative ion atmospheric pressure chemical ionisation

    Microsoft Academic Search

    E Razzazi-Fazeli; J Böhm; W Luf

    1999-01-01

    A new, rapid and sensitive method has been developed for the determination of nivalenol (NIV) and deoxynivalenol (DON) by using HPLC in combination with an atmospheric pressure chemical ionization (APCI)-interface and a single quadrupole mass spectrometer. Different LC and MS parameters have been optimized prior to this in order to obtain better results and sensitivity. The effect of nebulizing temperature

  17. Radio frequency induced ionized collisional flow model for application at atmospheric pressures

    E-print Network

    Roy, Subrata

    Radio frequency induced ionized collisional flow model for application at atmospheric pressures and radio frequency (rf) induced plasma-sheath dynamics, using multifluid equations. For the former, argon inherent in nonequilibrium discharges such as obtained through radio frequency (rf) or microwave excitation

  18. Atmospheric Pressure Surface Sampling/Ionization Techniques for Direct Coupling of Planar Separations with Mass Spectrometry

    SciTech Connect

    Pasilis, Sofie P [University of Idaho; Van Berkel, Gary J [ORNL

    2010-01-01

    Planar separations, which include thin layer chromatography and gel electrophoresis, are in widespread use as important and powerful tools for conducting separations of complex mixtures. To increase the utility of planar separations, new methods are needed that allow in-situ characterization of the individual components of the separated mixtures. A large number of atmospheric pressure surface sampling and ionization techniques for use with mass spectrometry have emerged in the past several years, and several have been investigated as a means for mass spectrometric read-out of planar separations. In this article, we review the atmospheric pressure surface sampling and ionization techniques that have been used for the read-out of planar separation media. For each technique, we briefly explain the operational basics and discuss the analyte type for which it is appropriate and some specific applications from the literature.

  19. Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films

    Microsoft Academic Search

    Minghui Yin; Lingli Zhao; Xiangyu Xu; Shouguo Wang

    2008-01-01

    Borophosphosilicate glass (BPSG) films have been grown on silicon wafers by plasma enhanced chemical vapor deposition at atmospheric pressure (AP-PECVD). Tetraethoxysilane (TEOS), triethylborate (TEB), and trimethylphosphite (TMPI) were adopted as precursors, and argon and oxygen were respectively used as the carrier and reactive gases to produce stable plasma at atmospheric pressure. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS),

  20. Modern Atmospheric Pressure Surface Sampling/Ionization Techniques in Mass Spectrometry

    SciTech Connect

    Pasilis, Sofie P [University of Idaho] [University of Idaho; Van Berkel, Gary J [ORNL] [ORNL

    2012-01-01

    Over the last few years, there has been a rapid increase in atmospheric pressure surface sampling/ionization techniques for mass spectrometry, dramatically expanding the range of sample types that can be analyzed. The growth in this field of mass spectrometry has also resulted in a plethora of new acronyms. In this encyclopedia article, the various techniques are first sorted into four major categories based on the method used for analyte desorption and then subcategorized by ionization method. The underlying principles of operation are explained and some representative applications are described.

  1. Atmospheric Pressure Ionization Permanent Magnet Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    PubMed Central

    Vilkov, Andrey N.; Gamage, Chaminda M.; Misharin, Alexander S.; Doroshenko, Vladimir M.; Tolmachev, Dmitry A.; Tarasova, Irina A.; Kharybin, Oleg N.; Novoselov, Konstantin P.; Gorshkov, Michael V.

    2007-01-01

    A new Fourier Transform Ion Cyclotron Resonance mass spectrometer based on a permanent magnet with an atmospheric pressure ionization source was designed and constructed. A mass resolving power (full-width-at-half-maximum) of up to 80,000 in the electron ionization mode and 25,000 in the electrospray mode was obtained. Also, a mass measurement accuracy at low-ppm level has been demonstrated for peptide mixtures in a mass range of up to 1,200 m/z in the isotopically resolved mass spectra. PMID:17587594

  2. Microplasma Discharge Vacuum Ultraviolet Photoionization Source for Atmospheric Pressure Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Symonds, Joshua M.; Gann, Reuben N.; Fernández, Facundo M.; Orlando, Thomas M.

    2014-09-01

    In this paper, we demonstrate the first use of an atmospheric pressure microplasma-based vacuum ultraviolet (VUV) photoionization source in atmospheric pressure mass spectrometry applications. The device is a robust, easy-to-operate microhollow cathode discharge (MHCD) that enables generation of VUV photons from Ne and Ne/H2 gas mixtures. Photons were detected by excitation of a microchannel plate detector and by analysis of diagnostic sample ions using a mass spectrometer. Reactive ions, charged particles, and metastables produced in the discharge were blocked from entering the ionization region by means of a lithium fluoride window, and photoionization was performed in a nitrogen-purged environment. By reducing the output pressure of the MHCD, we observed heightened production of higher-energy photons, making the photoionization source more effective. The initial performance of the MHCD VUV source has been evaluated by ionizing model analytes such as acetone, azulene, benzene, dimethylaniline, and glycine, which were introduced in solid or liquid phase. These molecules represent species with both high and low proton affinities, and ionization energies ranging from 7.12 to 9.7 eV.

  3. Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds.

    PubMed

    Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J; Benter, Thorsten

    2014-03-01

    We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry. PMID:24399666

  4. Capillary Atmospheric Pressure Electron Capture Ionization (cAPECI): A Highly Efficient Ionization Method for Nitroaromatic Compounds

    NASA Astrophysics Data System (ADS)

    Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J.; Benter, Thorsten

    2014-03-01

    We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2 - or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2 - leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

  5. Electron density and temperature measurement by continuum radiation emitted from weakly ionized atmospheric pressure plasmas

    SciTech Connect

    Park, Sanghoo; Choe, Wonho, E-mail: wchoe@kaist.ac.kr [Department of Physics, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Youn Moon, Se [High-enthalpy Plasma Research Center, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju 561-756 (Korea, Republic of); Park, Jaeyoung [5771 La Jolla Corona Drive, La Jolla, CA 92037 (United States)

    2014-02-24

    The electron-atom neutral bremsstrahlung continuum radiation emitted from weakly ionized plasmas is investigated for electron density and temperature diagnostics. The continuum spectrum in 450–1000?nm emitted from the argon atmospheric pressure plasma is found to be in excellent agreement with the neutral bremsstrahlung formula with the electron-atom momentum transfer cross-section given by Popovi?. In 280–450?nm, however, a large discrepancy between the measured and the neutral bremsstrahlung emissivities is observed. We find that without accounting for the radiative H{sub 2} dissociation continuum, the temperature, and density measurements would be largely wrong, so that it should be taken into account for accurate measurement.

  6. Investigations of analyte-specific response saturation and dynamic range limitations in atmospheric pressure ionization mass spectrometry.

    PubMed

    Alfaro, Clint M; Uwakweh, Agbo-Oma; Todd, Daniel A; Ehrmann, Brandie M; Cech, Nadja B

    2014-11-01

    With this study, we investigated why some small molecules demonstrate narrow dynamic ranges in electrospray ionization-mass spectrometry (ESI-MS) and sought to establish conditions under which the dynamic range could be extended. Working curves were compared for eight flavonoids and two alkaloids using ESI, atmospheric pressure chemical ionization (APCI), and heated electrospray ionization (HESI) sources. Relative to reserpine, the flavonoids exhibited narrower linear dynamic ranges with ESI-MS, primarily due to saturation in response at relatively low concentrations. Saturation was overcome by switching from ESI to APCI, and our experiments utilizing a combination HESI/APCI source suggest that this is due in part to the ability of APCI to protonate neutral quercetin molecules in the gas phase. Thermodynamic equilibrium calculations indicate that quercetin should be fully protonated in solution, and thus, it appears that some factor inherent in the ESI process favors the formation of neutral quercetin at high concentration. The flavonoid saturation concentration was increased with HESI as compared to ESI, suggesting that inefficient transfer of ions to the gas phase can also contribute to saturation in ESI-MS response. In support of this conclusion, increasing auxiliary gas pressure or switching to a more volatile spray solvent also increased the ESI dynamic range. Among the sources investigated herein, the HESI source achieved the best analytical performance (widest linear dynamic range, lowest LOD), but the APCI source was less subject to saturation in response at high concentration. PMID:25268329

  7. Production of Fullerenes by Low Temperature Plasma Chemical Vaper Deposition under Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Inomata, Kiyoto; Aoki, Nobuyuki; Koinuma, Hideomi

    1994-02-01

    A gas phase reactor developed for generating homogenous low temperature plasma under atmospheric pressure was found to provide a new method for producing fullerenes by a plasma chemical vapor deposition (CVD) process. Into an afterglow region of atmospheric pressure Ar He mixed gas plasma, an aromatic hydrocarbon was introduced and decomposed into black soot under appropriate reaction conditions. A benzene solution of the soot showed two clear HPLC peaks with retention times corresponding well to those of C60 and C70. The formation of C60 was further confirmed by UV spectroscopy.

  8. Atmospheric pressure chemical ionisation mass spectrometry for in vivo analysis of volatile flavour release

    Microsoft Academic Search

    A. J. Taylor; R. S. T. Linforth; B. A. Harvey; A. Blake

    2000-01-01

    To follow volatile flavour release in the expired air of people during eating, several physiological and analytical constraints must be observed to obtain good quality data. An interface has been developed to sample air from the nose and ionise the volatile compounds contained therein by atmospheric pressure chemical ionisation. The ions formed are detected in a quadrupole mass spectrometer. The

  9. Decontamination of chemical and biological warfare (CBW) agents using an atmospheric pressure plasma jet (APPJ)

    SciTech Connect

    Herrmann, H.W.; Henins, I.; Park, J.; Selwyn, G.S. [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1999-05-01

    The atmospheric pressure plasma jet (APPJ) [A. Sch{umlt u}tze {ital et al.}, IEEE Trans. Plasma Sci. {bold 26}, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O{sub 2}/H{sub 2}O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz rf. While passing through the plasma, the feedgas becomes excited, dissociated or ionized by electron impact. Once the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains neutral metastable species (e.g., O{sub 2}{sup {asterisk}}, He{sup {asterisk}}) and radicals (e.g., O, OH). This reactive effluent has been shown to be an effective neutralizer of surrogates for anthrax spores and mustard blister agent. Unlike conventional wet decontamination methods, the plasma effluent does not cause corrosion and it does not destroy wiring, electronics, or most plastics, making it highly suitable for decontamination of sensitive equipment and interior spaces. Furthermore, the reactive species in the effluent rapidly degrade into harmless products leaving no lingering residue or harmful by-products. {copyright} {ital 1999 American Institute of Physics.}

  10. Determination of nitrogen monoxide in high purity nitrogen gas with an atmospheric pressure ionization mass spectrometer

    NASA Technical Reports Server (NTRS)

    Kato, K.

    1985-01-01

    An atmospheric pressure ionization mass spectrometric (API-MS) method was studied for the determination of residual NO in high purity N2 gas. The API-MS is very sensitive to NO, but the presence of O2 interferes with the NO measurement. Nitrogen gas in cylinders as sample gas was mixed with NO standard gas and/or O2 standard gas, and then introduced into the API-MS. The calibration curves of NO and O2 has linearity in the region of 0 - 2 ppm, but the slopes changed with every cylinder. The effect of O2 on NO+ peak was additive and proportional to O2 concentration in the range of 0 - 0.5 ppm. The increase in NO+ intensity due to O2 was (0.07 - 0.13)%/O2, 1 ppm. Determination of NO and O2 was carried out by the standard addition method to eliminate the influence of variation of slopes. The interference due to O2 was estimated from the product of the O2 concentration and the ratio of slope A to Slope B. Slope A is the change in the NO+ intensity with the O2 concentration. Slope B is the intensity with O2 concentration.

  11. The Protonation Site of para-Dimethylaminobenzoic Acid Using Atmospheric Pressure Ionization Methods.

    PubMed

    Chai, Yunfeng; Weng, Guofeng; Shen, Shanshan; Sun, Cuirong; Pan, Yuanjiang

    2015-04-01

    The protonation site of para-dimethylaminobenzoic acid (p-DMABA) was investigated using atmospheric pressure ionization methods (ESI and APCI) coupled with collision-induced dissociation (CID), nuclear magnetic resonance (NMR), and computational chemistry. Theoretical calculations and NMR experiments indicate that the dimethyl amino group is the preferred site of protonation both in the gas phase and aqueous solution. Protonation of p-DMABA occurs at the nitrogen atom by ESI independent of the solvents and other operation conditions under typical thermodynamic control. However, APCI produces a mixture of the nitrogen- and carbonyl oxygen-protonated p-DMABA when aprotic organic solvents (acetonitrile, acetone, and tetrahydrofuran) are used, exhibiting evident kinetic characteristics of protonation. But using protic organic solvents (methanol, ethanol, and isopropanol) in APCI still leads to the formation of thermodynamically stable N-protonated p-DMABA. These structural assignments were based on the different CID behavior of the N- and O-protonated p-DMABA. The losses of methyl radical and water are the diagnostic fragmentations of the N- and O-protonated p-DMABA, respectively. In addition, the N-protonated p-DMABA is more stable than the O-protonated p-DMABA in CID revealed by energy resolved experiments and theoretical calculations. PMID:25627246

  12. The Protonation Site of para-Dimethylaminobenzoic Acid Using Atmospheric Pressure Ionization Methods

    NASA Astrophysics Data System (ADS)

    Chai, Yunfeng; Weng, Guofeng; Shen, Shanshan; Sun, Cuirong; Pan, Yuanjiang

    2015-01-01

    The protonation site of para-dimethylaminobenzoic acid (p-DMABA) was investigated using atmospheric pressure ionization methods (ESI and APCI) coupled with collision-induced dissociation (CID), nuclear magnetic resonance (NMR), and computational chemistry. Theoretical calculations and NMR experiments indicate that the dimethyl amino group is the preferred site of protonation both in the gas phase and aqueous solution. Protonation of p-DMABA occurs at the nitrogen atom by ESI independent of the solvents and other operation conditions under typical thermodynamic control. However, APCI produces a mixture of the nitrogen- and carbonyl oxygen-protonated p-DMABA when aprotic organic solvents (acetonitrile, acetone, and tetrahydrofuran) are used, exhibiting evident kinetic characteristics of protonation. But using protic organic solvents (methanol, ethanol, and isopropanol) in APCI still leads to the formation of thermodynamically stable N-protonated p-DMABA. These structural assignments were based on the different CID behavior of the N- and O-protonated p-DMABA. The losses of methyl radical and water are the diagnostic fragmentations of the N- and O-protonated p-DMABA, respectively. In addition, the N-protonated p-DMABA is more stable than the O-protonated p-DMABA in CID revealed by energy resolved experiments and theoretical calculations.

  13. The Protonation Site of para-Dimethylaminobenzoic Acid Using Atmospheric Pressure Ionization Methods

    NASA Astrophysics Data System (ADS)

    Chai, Yunfeng; Weng, Guofeng; Shen, Shanshan; Sun, Cuirong; Pan, Yuanjiang

    2015-04-01

    The protonation site of para-dimethylaminobenzoic acid ( p-DMABA) was investigated using atmospheric pressure ionization methods (ESI and APCI) coupled with collision-induced dissociation (CID), nuclear magnetic resonance (NMR), and computational chemistry. Theoretical calculations and NMR experiments indicate that the dimethyl amino group is the preferred site of protonation both in the gas phase and aqueous solution. Protonation of p-DMABA occurs at the nitrogen atom by ESI independent of the solvents and other operation conditions under typical thermodynamic control. However, APCI produces a mixture of the nitrogen- and carbonyl oxygen-protonated p-DMABA when aprotic organic solvents (acetonitrile, acetone, and tetrahydrofuran) are used, exhibiting evident kinetic characteristics of protonation. But using protic organic solvents (methanol, ethanol, and isopropanol) in APCI still leads to the formation of thermodynamically stable N-protonated p-DMABA. These structural assignments were based on the different CID behavior of the N- and O-protonated p-DMABA. The losses of methyl radical and water are the diagnostic fragmentations of the N- and O-protonated p-DMABA, respectively. In addition, the N-protonated p-DMABA is more stable than the O-protonated p-DMABA in CID revealed by energy resolved experiments and theoretical calculations.

  14. A Novel APPI-MS Setup for In Situ Degradation Product Studies of Atmospherically Relevant Compounds: Capillary Atmospheric Pressure Photo Ionization (cAPPI)

    Microsoft Academic Search

    Hendrik Kersten; Valerie Derpmann; Ian Barnes; Klaus J. Brockmann; Rob O’Brien; Thorsten Benter

    We report on the development of a novel atmospheric pressure photoionization setup and its applicability for in situ degradation\\u000a product studies of atmospherically relevant compounds. A custom miniature spark discharge lamp was embedded into an ion transfer\\u000a capillary, which separates the atmospheric pressure from the low pressure region in the first differential pumping stage of\\u000a a conventional atmospheric pressure ionization

  15. Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition of Borophosphosilicate Glass Films

    NASA Astrophysics Data System (ADS)

    Yin, Minghui; Zhao, Lingli; Xu, Xiangyu; Wang, Shouguo

    2008-03-01

    Borophosphosilicate glass (BPSG) films have been grown on silicon wafers by plasma enhanced chemical vapor deposition at atmospheric pressure (AP-PECVD). Tetraethoxysilane (TEOS), triethylborate (TEB), and trimethylphosphite (TMPI) were adopted as precursors, and argon and oxygen were respectively used as the carrier and reactive gases to produce stable plasma at atmospheric pressure. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and refractive index and stress measurements were employed to characterize BPSG films. The effects of input radio-frequency (RF) power and precursor (TEB and TMPI) flow rate on deposition rate were studied. Results indicated that the deposition rate of BPSG films increases with increasing input RF power and precursor flow rate. In addition, reactive gaseous species were detected by optical emission spectroscopy to reveal the possible reaction process of BPSG film deposition.

  16. Aliphatic Hydrocarbon Spectra by Helium Ionization Mass Spectrometry (HIMS) on a Modified Atmospheric-Pressure Source Designed for Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Yang, Zhihua; Attygalle, Athula B.

    2011-08-01

    Chemical-ionization techniques that use metastable species to ionize analytes traditionally use a flat pin or a sharp solid needle onto which the high potential needed to generate the discharge plasma is applied. We report here that direct analysis of samples containing volatile and semivolatile compounds, including saturated and unsaturated aliphatic hydrocarbons, can be achieved on any electrospray-ionization mass spectrometer by passing helium though the sample delivery metal capillary held at a high potential. In the helium plasma ionization source (HPIS) described here, the typical helium flow required (about 20-30 mL/min), was significantly lower than that needed for other helium-ionization sources. By this procedure, positive ions were generated by nominal hydride ion removal from molecules emanating from heated saturated hydrocarbons as large as tetratetracontane (C44H90), at capillary voltages ranging from 2.0 to 4.0 kV. Unsaturated hydrocarbons, on the other hand, underwent facile protonation under much lower capillary voltages (0.9 to 2.0 kV). Although saturated and monounsaturated hydrocarbons bearing the same number of carbon atoms generate ions of the same m/z ratio, a gas-phase deuterium exchange method is described to ascertain the identity of these isomeric ions originating from either protonation or hydride abstraction mechanisms. Moreover, mass spectrometric results obtained by exposing unsaturated hydrocarbons to D2O vapor in an HPIS-MS instrument confirmed that the proton donor for ionization of unsaturated hydrocarbons is protonated water.

  17. Solid-phase extraction combined with high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis of pesticides in water: method performance and application in a reconnaissance survey of residues in drinking water in Greater Cairo, Egypt.

    PubMed

    Potter, Thomas L; Mohamed, Mahmoud A; Ali, Hannah

    2007-01-24

    Monitoring of water resources for pesticide residues is often needed to ensure that pesticide use does not adversely impact the quality of public water supplies or the environment. In many rural areas and throughout much of the developing world, monitoring is often constrained by lack of testing facilities; thus, collection of samples and shipment to centralized laboratories for analysis is required. The portability, ease of use, and potential to enhance analyte stability make solid-phase extraction (SPE) an attractive technique for handling water samples prior to their shipment. We describe performance of an SPE method targeting a structurally diverse mixture of 25 current-use pesticides and two common degradates in samples of raw and filtered drinking water collected in Greater Cairo, Egypt. SPE was completed in a field laboratory in Egypt, and cartridges were shipped to the United States for elution and high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis. Quantitative and reproducible recovery of 23 of 27 compounds (average = 96%; percent relative standard deviation = 21%) from matrix spikes (1 microg L-1 per component) prepared in the field and from deionized water fortified similarly in the analytical laboratory was obtained. Concurrent analysis of unspiked samples identified four parent compounds and one degradate in drinking water samples. No significant differences were observed between raw and filtered samples. Residue levels in all cases were below drinking water and "harm to aquatic-life" thresholds, indicating that human and ecological risks of pesticide contamination were relatively small; however, the study was limited in scale and scope. Further monitoring is needed to define spatial and temporal variation in residue concentrations. The study has demonstrated the feasibility of performing studies of this type using SPE to extract and preserve samples in the field. The approach should be broadly applicable in many settings. PMID:17227043

  18. Epitaxial Growth of Zinc Oxide Whiskers by Chemical-Vapor Deposition under Atmospheric Pressure

    Microsoft Academic Search

    Minoru Satoh; Norio Tanaka; Yoshikazu Ueda; Shigeo Saitoh; Hidetoshi Saitoh

    1999-01-01

    ZnO whiskers were epitaxially grown by a chemical-vapor deposition technique employed at atmospheric pressure. Highly oriented ZnO whiskers grew at a substrate temperature of 550°C on (0001)alpha-Al2O3 substrates with a growth rate of 3.7 nm\\/s. X-ray diffractometry revealed that the epitaxial relationship between the whiskers and the substrate was determined as ZnO[\\\\bar{1}010](0001)\\/\\/Al2O3[\\\\bar{1}2\\\\bar{1}0](0001) or ZnO[\\\\bar{1}2\\\\bar{1}0](0001)\\/\\/Al2O3[\\\\bar{1}010](0001). In addition, the full-width at half

  19. Titanium arsenide films from the atmospheric pressure chemical vapour deposition of tetrakisdimethylamidotitanium and tert-butylarsine.

    PubMed

    Thomas, Tegan; Blackman, Christopher S; Parkin, Ivan P; Carmalt, Claire J

    2011-10-28

    Thin films of titanium arsenide have been deposited from the atmospheric pressure chemical vapour deposition (APCVD) of [Ti(NMe(2))(4)] and (t)BuAsH(2) at substrate temperatures between 350-550 °C. Highly reflective, silver coloured films were obtained which showed borderline metallic-semiconductor resistivities. The titanium arsenide films were analyzed by scanning electron microscopy (SEM), Raman spectroscopy, wavelength dispersive analysis of X-rays (WDX), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The films showed variable titanium to arsenic ratios but at substrate temperatures of 500 and 550 °C films with a 1 : 1 ratio of Ti : As, consistent with the composition TiAs, were deposited. Powder XRD showed that all of the films were crystalline and consistent with the formation of TiAs. Both nitrogen and carbon contamination of the films were negligible. PMID:21743910

  20. Capillary column supercritical fluid chromatography-atmospheric pressure ionisation mass spectrometry interface performance of atmospheric pressure chemical ionisation and electrospray ionisation.

    PubMed

    Sjöberg, P J; Markides, K E

    1999-09-01

    A supercritical fluid chromatography interface probe for atmospheric pressure ionisation mass spectrometry (API-MS) with the advantage of convenient switch between ionisation modes [atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI)] has recently been reported [P.J.R. Sjöberg, K.E. Markides, J. Chromatogr. A, 785 (1997) 101]. In order to obtain a stable ion signal and a low minimum detectable quantity, the design of the spray devise has to be optimised. For easy optimisation in the APCI mode, the corona needle was mounted directly on the interface probe. To compensate for the adiabatic cooling of the expanding mobile phase in the APCI mode, a heated region around the restrictor tip was used. In comparison, ESI required no additional heat, which might also prevent fragmentation for thermolabile compounds. As the mobile phase used was neat CO2, a low flow of make-up liquid was utilised in the ESI mode for transfer of the analytes from the expanding CO2 gas to the liquid phase before ionisation. The low make-up liquid flow in the ESI mode was sufficient for preventing the restrictor from becoming blocked. Factors that influence the ion signal intensity and stability have been studied. In APCI mode, corona needle position, nebuliser gas flow and gas additives were studied and in ESI mode, spray capillary assembly dimension and position, liquid flow-rate and composition were studied. The achievable detection limits were in the 50-0.1 pg (i.e., 290 fmol-140 amol) range. The detection limit in APCI mode was improved by a factor of about 20-25 compared to an earlier design [L.N. Tyrefors, R.X. Moulder, K.E. Markides, Anal. Chem. 65 (1993) 2835]. PMID:10514996

  1. Modeling chemical vapor deposition of silicon dioxide in microreactors at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a multiphysics mathematical model for simulation of silicon dioxide Chemical Vapor Deposition (CVD) from tetraethyl orthosilicate (TEOS) and oxygen mixture in a microreactor at atmospheric pressure. Microfluidics is a promising technology with numerous applications in chemical synthesis due to its high heat and mass transfer efficiency and well-controlled flow parameters. Experimental studies of CVD microreactor technology are slow and expensive. Analytical solution of the governing equations is impossible due to the complexity of intertwined non-linear physical and chemical processes. Computer simulation is the most effective tool for design and optimization of microreactors. Our computational fluid dynamics model employs mass, momentum and energy balance equations for a laminar transient flow of a chemically reacting gas mixture at low Reynolds number. Simulation results show the influence of microreactor configuration and process parameters on SiO2 deposition rate and uniformity. We simulated three microreactors with the central channel diameter of 5, 10, 20 micrometers, varying gas flow rate in the range of 5-100 microliters per hour and temperature in the range of 300-800 °C. For each microchannel diameter we found an optimal set of process parameters providing the best quality of deposited material. The model will be used for optimization of the microreactor configuration and technological parameters to facilitate the experimental stage of this research.

  2. Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer.

    PubMed

    Albrecht, Sascha; Klopotowski, Sebastian; Derpmann, Valerie; Klee, Sonja; Brockmann, Klaus J; Stroh, Fred; Benter, Thorsten

    2014-01-01

    In this study a thermally sampling atmospheric pressure ionization mass spectrometer is described and characterized. The ion transfer stage offers the capability to sample cluster ions at thermal equilibrium and during this transfer fundamental processes possibly affecting the cluster distribution are also readily identified. Additionally, the transfer stage combines optional collision-induced dissociation (CID) analysis of the cluster composition with thermal equilibrium sampling of clusters. The performance of the setup is demonstrated with regard to the proton-bound water cluster system. The benefit of the studied processes is that they can help to improve future transfer stages and to understand cluster ion reactions in ion mobility tubes and high-pressure ion sources. In addition, the instrument allows for the identification of fragmentation and protonation reactions caused by CID. PMID:24517784

  3. Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer

    SciTech Connect

    Albrecht, Sascha, E-mail: s.albrecht@fz-juelich.de; Stroh, Fred, E-mail: f.stroh@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich (Germany)] [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Stratosphere (IEK-7), 52428 Jülich (Germany); Klopotowski, Sebastian, E-mail: s.klopotowski@uni-wuppertal.de; Derpmann, Valerie, E-mail: v.derpmann@uni-wuppertal.de; Klee, Sonja, E-mail: s.klee@uni-wuppertal.de; Brockmann, Klaus J., E-mail: brockma@uni-wuppertal.de; Benter, Thorsten, E-mail: tbenter@uni-wuppertal.de [Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal (Germany)] [Physical and Theoretical Chemistry, Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, 42097 Wuppertal (Germany)

    2014-01-15

    In this study a thermally sampling atmospheric pressure ionization mass spectrometer is described and characterized. The ion transfer stage offers the capability to sample cluster ions at thermal equilibrium and during this transfer fundamental processes possibly affecting the cluster distribution are also readily identified. Additionally, the transfer stage combines optional collision-induced dissociation (CID) analysis of the cluster composition with thermal equilibrium sampling of clusters. The performance of the setup is demonstrated with regard to the proton-bound water cluster system. The benefit of the studied processes is that they can help to improve future transfer stages and to understand cluster ion reactions in ion mobility tubes and high-pressure ion sources. In addition, the instrument allows for the identification of fragmentation and protonation reactions caused by CID.

  4. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Zhanguo; Li, Ying; Cao, Peng; Zhao, Hongjie

    2013-07-01

    An atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experimental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination process, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride (PVC), polyethylene (PE), phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chromatism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet.

  5. Direct atmospheric pressure chemical ionisation ion trap mass spectrometry for aroma analysis: Speed, sensitivity and resolution of isobaric compounds

    Microsoft Academic Search

    Lionel Jublot; Robert S. T. Linforth; Andrew J. Taylor

    2005-01-01

    Atmospheric pressure chemical ionisation (APCI) sources were developed for real time analysis of volatile release from foods using an ion trap (IT) mass spectrometer (MS). Key objectives were spectral simplicity (minimal fragmentation), response time and signal to noise ratio. The benefits of APCI-IT-MS were assessed by comparing the performance for in vivo and headspace analyses with that obtained using APCI

  6. Atmospheric pressure chemical vapor deposition of transparent conducting films of fluorine doped zinc oxide and their application

    E-print Network

    Atmospheric pressure chemical vapor deposition of transparent conducting films of fluorine doped+Business Media, LLC 2007 Abstract Transparent conducting ZnO:F was deposited as thin films on soda lime glass the other transparent conducting oxides. Cadmium in all its compounds is toxic and carcinogenic

  7. Plasma-Spray Ionization (PLASI): A Multimodal Atmospheric Pressure Ion Source for Liquid Stream Analysis

    NASA Astrophysics Data System (ADS)

    Kaylor, Adam; Dwivedi, Prabha; Pittman, Jennifer J.; Monge, María Eugenia; Cheng, Guilong; Li, Shelly; Fernández, Facundo M.

    2014-10-01

    A new ion generation method, named plasma-spray ionization (PLASI) for direct analysis of liquid streams, such as in continuous infusion experiments or liquid chromatography (LC), is reported. PLASI addresses many of the analytical limitations of electrospray ionization (ESI) and has potential for real time process stream analysis and reaction monitoring under atmospheric conditions in non-ESI friendly scenarios. In PLASI-mass spectrometry (MS), the liquid stream is pneumatically nebulized and partially charged at low voltages; the resultant aerosol is thus entrained with a gaseous plasma plume from a distal glow discharge prior to MS detection. PLASI-MS not only overcomes ESI-MS limitations but also generates simpler mass spectra with minimal adduct and cluster formation. PLASI utilizes the atomization capabilities of an ESI sprayer operated below the ESI threshold to generate gas-phase aerosols that are then ionized by the plasma stream. When operated at or above the ESI threshold, ionization by traditional ESI mechanisms is achieved. The multimodal nature of the technique enables readily switching between plasma and ESI operation. It is expected that PLASI will enable analyzing a wide range of analytes in complex matrices and less-restricted solvent systems, providing more flexibility than that achievable by ESI alone.

  8. Plasma-spray ionization (PLASI): a multimodal atmospheric pressure ion source for liquid stream analysis.

    PubMed

    Kaylor, Adam; Dwivedi, Prabha; Pittman, Jennifer J; Monge, María Eugenia; Cheng, Guilong; Li, Shelly; Fernández, Facundo M

    2014-10-01

    A new ion generation method, named plasma-spray ionization (PLASI) for direct analysis of liquid streams, such as in continuous infusion experiments or liquid chromatography (LC), is reported. PLASI addresses many of the analytical limitations of electrospray ionization (ESI) and has potential for real time process stream analysis and reaction monitoring under atmospheric conditions in non-ESI friendly scenarios. In PLASI-mass spectrometry (MS), the liquid stream is pneumatically nebulized and partially charged at low voltages; the resultant aerosol is thus entrained with a gaseous plasma plume from a distal glow discharge prior to MS detection. PLASI-MS not only overcomes ESI-MS limitations but also generates simpler mass spectra with minimal adduct and cluster formation. PLASI utilizes the atomization capabilities of an ESI sprayer operated below the ESI threshold to generate gas-phase aerosols that are then ionized by the plasma stream. When operated at or above the ESI threshold, ionization by traditional ESI mechanisms is achieved. The multimodal nature of the technique enables readily switching between plasma and ESI operation. It is expected that PLASI will enable analyzing a wide range of analytes in complex matrices and less-restricted solvent systems, providing more flexibility than that achievable by ESI alone. PMID:25001384

  9. Determination of 17 illicit drugs in oral fluid using isotope dilution ultra-high performance liquid chromatography/tandem mass spectrometry with three atmospheric pressure ionizations.

    PubMed

    Wang, I-Ting; Feng, Yu-Ting; Chen, Chia-Yang

    2010-11-15

    The collection of oral fluid for drug testing is easy and non-invasive. This study developed a drug testing method using ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS) in selected-reaction monitoring (SRM) mode. We tested the method on the analysis of four opiates and their metabolites, five amphetamines, flunitrazepam and its two metabolites, and cocaine and its four metabolites in oral fluid. 100-?L samples of oral fluid were diluted with twice the amount of water then spiked with isotope-labeled internal standards. After the samples had undergone high-speed centrifugation for 20 min, we analyzed the supernatant. The recovery of the sample preparation ranged from 81 to 108%. We compared the performance of electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). The ion suppression of most analytes on ESI (28-78%) was lower than that of APCI and APPI. A post-column flow split (5:1) did not reduce the matrix effect on ESI. Direct APPI performed better than dopant-assisted APPI using toluene. ESI, APCI and APPI limits of quantitation mostly ranged from 0.11 to 1.9 ng/mL, 0.02 to 2.2 ng/mL and 0.02 to 2.1 ng/mL, respectively, but were much higher on amphetamine and ecgonine methyl ester (about 2.7-4.7 ng/mL, 8.7-14 ng/mL, and 10-19 ng/mL, respectively). Most of the bias percentages (accuracy) and relative standard deviations (precision) on spiked samples were below 15%. This method greatly simplifies the process of sample preparation and shortens the chromatographic time to only 7.5 min per run and is able to detect analytes at sub-ppb levels. PMID:20951654

  10. Threefold atmospheric-pressure annealing for suppressing graphene nucleation on copper in chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Suzuki, Seiya; Nagamori, Takashi; Matsuoka, Yuki; Yoshimura, Masamichi

    2014-09-01

    Chemical vapor deposition (CVD) is a promising method of producing a large single-crystal graphene on a catalyst, especially on copper (Cu), and a further increase in domain size is desirable for electro/optic applications. Here, we report on threefold atmospheric-pressure (ATM) annealing for suppressing graphene nucleation in atmospheric CVD. Threefold ATM annealing formed a step and terrace surface of the underlying Cu, in contrast to ATM annealing. Atomic force microscopy and Auger electron mapping revealed that Si-containing particles existed on threefold-ATM- and ATM-annealed surfaces; particles on Cu had a lower density after threefold ATM annealing than after ATM annealing. The formation of a step and terrace surface and the lower density of particles following the threefold ATM annealing would play a role in reducing graphene nucleation. By combining threefold ATM annealing and electropolishing of Cu, the nucleation of graphene was effectively suppressed, and a submillimeter-sized hexagonal single-crystal graphene was successfully obtained.

  11. Atmospheric Pressure Spray Chemical Vapor Deposited CuInS2 Thin Films for Photovoltaic Applications

    NASA Technical Reports Server (NTRS)

    Harris, J. D.; Raffaelle, R. P.; Banger, K. K.; Smith, M. A.; Scheiman, D. A.; Hepp, A. F.

    2002-01-01

    Solar cells have been prepared using atmospheric pressure spray chemical vapor deposited CuInS2 absorbers. The CuInS2 films were deposited at 390 C using the single source precursor (PPh3)2CuIn(SEt)4 in an argon atmosphere. The absorber ranges in thickness from 0.75 - 1.0 micrometers, and exhibits a crystallographic gradient, with the leading edge having a (220) preferred orientation and the trailing edge having a (112) orientation. Schottky diodes prepared by thermal evaporation of aluminum contacts on to the CuInS2 yielded diodes for films that were annealed at 600 C. Solar cells were prepared using annealed films and had the (top down) composition of Al/ZnO/CdS/CuInS2/Mo/Glass. The Jsc, Voc, FF and (eta) were 6.46 mA per square centimeter, 307 mV, 24% and 0.35%, respectively for the best small area cells under simulated AM0 illumination.

  12. Chemical and biomolecule patterning on 2D surfaces using atmospheric pressure microcavity plasma array devices

    NASA Astrophysics Data System (ADS)

    Al-Bataineh, Sameer A.; Szili, Endre J.; Desmet, Gillies; Ruschitzka, Paul; Gruner, Philipp J.; Priest, Craig; Voelcker, Nicolas H.; Steele, David A.; Short, Robert D.; Griesser, Hans J.

    2011-12-01

    This paper presents a method for chemical and biomolecule patterning on planar (2D) surfaces using atmospheric pressure microplasmas. Spatially controlled surface modification is important for the development of emerging technologies such as microfluidic lab-on-a-chip devices, biosensors and other diagnostics tools. A non-fouling layer of poly(N-isopropylacrylamide) aldehyde (pNIPAM-ald) polymer, grafted onto heptylamine plasma polymer (HApp) modified silicon substrates, was used to achieve this goal. The non-fouling behaviour of the pNIPAM-ald coating was investigated at a temperature below its lower critical solution temperature (LCST) using human serum albumin (HSA). XPS and ToF-SIMS were used to characterise the plasma polymer coating and its subsequent modification with pNIPAM-ald before and after HSA adsorption. A 7 x 7 microcavity plasma array device (each cavity had a 250 ?m diameter and was separated by 500 ?m) was used for microplasma patterning. In a non-contact mode, helium microplasma treatment of the pNIPAM-ald coating was carried out for 60 s. The polymer coating was removed from regions directly exposed to microplasma cavities, as shown by ToF-SIMS. Microplasma treated regions were able to support the adsorption of fluorescently-labelled streptavidin whereas the rest of the coating was still non-fouling. This approach therefore resulted in spatially separated areas of immobilised protein.

  13. Atmospheric pressure ionization time-of-flight mass spectrometer for real-time explosives vapor detection

    NASA Astrophysics Data System (ADS)

    Lee, Harold G.; Lee, Edgar D.; Lee, Milton L.

    1992-05-01

    In this study we report a high-sensitivity, easy-to-use chemical analyzer for the detection of trace volatile explosive chemicals in ambient air, based on a time-of-flight mass spectrometer (TOFMS) with an API source. Because of its unique design, it is much more sensitive than other mass spectrometers; subfemtogram (less than 10(exp -15) g) detection limits are possible. As with other mass spectrometers, the TOFMS separates ions according to their mass-to-charge ratio and thus gives the best selectivity among all other non-MS based detectors. The ultrahigh sensitivity obtained in TOFMS precludes the use of a preconcentration stage. The mass resolution is approximately 500. Simultaneous analyses for up to 16 compounds can be accomplished within 200 microseconds.

  14. Capillary electrochromatography-atmospheric pressure ionization mass spectrometry of pesticides using a surfactant-bound monolithic column

    PubMed Central

    Gu, Congying; Shamsi, Shahab A.

    2011-01-01

    A surfactant bound poly (11-acrylaminoundecanoic acid-ethylene dimethacrylate) (AAUA-EDMA) monolithic column was simply prepared by in-situ co-polymerization of AAUA and EDMA with 1-propanol, 1,4-butanediol and water as porogens in 100 µm id fused silica capillary in one step. This column was used in capillary electrochromatography (CEC)-atmospheric pressure photoionization (APPI)-mass spectrometry system for separation and detection of N-methylcarbamates (NMCs) pesticides. Numerous parameters are optimized for CEC-APPI-MS. After evaluation of the mobile phase composition, sheath liquid composition and the monolithic capillary outlet position, a fractional factorial design (FFD) was selected as a screening procedure to identify factors of ionization source parameters, such as sheath liquid flow rate, drying gas flow rate, drying gas temperature, nebulizing gas pressure, vaporizer temperature, and capillary voltage, which significantly influence APPI-MS sensitivity. A face-centered central composite design (CCD) was further utilized to optimize the most significant parameters and predict the best sensitivity. Under optimized conditions signal-to-noise ratios (S/N) around 78 were achieved for an injection of 100 ng/mL of each pesticide. Finally, this CEC-APPI-MS method was successfully applied to the analysis of nine NMCs in spiked apple juice sample after solid phase extraction with recoveries in the range of 65 to 109%. PMID:20349511

  15. On-line coating of glass with tin oxide by atmospheric pressure chemical vapor deposition.

    SciTech Connect

    Allendorf, Mark D.; Sopko, J.F. (PPF Industries, Pittsburgh, PA); Houf, William G.; Chae, Yong Kee; McDaniel, Anthony H.; Li, M. (PPF Industries, Pittsburgh, PA); McCamy, J.W. (PPF Industries, Pittsburgh, PA)

    2006-11-01

    Atmospheric pressure chemical vapor deposition (APCVD) of tin oxide is a very important manufacturing technique used in the production of low-emissivity glass. It is also the primary method used to provide wear-resistant coatings on glass containers. The complexity of these systems, which involve chemical reactions in both the gas phase and on the deposition surface, as well as complex fluid dynamics, makes process optimization and design of new coating reactors a very difficult task. In 2001 the U.S. Dept. of Energy Industrial Technologies Program Glass Industry of the Future Team funded a project to address the need for more accurate data concerning the tin oxide APCVD process. This report presents a case study of on-line APCVD using organometallic precursors, which are the primary reactants used in industrial coating processes. Research staff at Sandia National Laboratories in Livermore, CA, and the PPG Industries Glass Technology Center in Pittsburgh, PA collaborated to produce this work. In this report, we describe a detailed investigation of the factors controlling the growth of tin oxide films. The report begins with a discussion of the basic elements of the deposition chemistry, including gas-phase thermochemistry of tin species and mechanisms of chemical reactions involved in the decomposition of tin precursors. These results provide the basis for experimental investigations in which tin oxide growth rates were measured as a function of all major process variables. The experiments focused on growth from monobutyltintrichloride (MBTC) since this is one of the two primary precursors used industrially. There are almost no reliable growth-rate data available for this precursor. Robust models describing the growth rate as a function of these variables are derived from modeling of these data. Finally, the results are used to conduct computational fluid dynamic simulations of both pilot- and full-scale coating reactors. As a result, general conclusions are reached concerning the factors affecting the growth rate in on-line APCVD reactors. In addition, a substantial body of data was generated that can be used to model many different industrial tin oxide coating processes. These data include the most extensive compilation of thermochemistry for gas-phase tin-containing species as well as kinetic expressions describing tin oxide growth rates over a wide range of temperatures, pressures, and reactant concentrations.

  16. Automatic Sampling and Analysis of Organics and Biomolecules by Capillary Action-Supported Contactless Atmospheric Pressure Ionization Mass Spectrometry

    PubMed Central

    Hsieh, Cheng-Huan; Meher, Anil Kumar; Chen, Yu-Chie

    2013-01-01

    Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (?1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated. PMID:23762484

  17. Automatic sampling and analysis of organics and biomolecules by capillary action-supported contactless atmospheric pressure ionization mass spectrometry.

    PubMed

    Hsieh, Cheng-Huan; Meher, Anil Kumar; Chen, Yu-Chie

    2013-01-01

    Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (?1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated. PMID:23762484

  18. Atmospheric Pressure Dielectric Barrier Discharges Under Unipolar and Bipolar HV Excitation in View of Chemical Reactivity in Afterglow Conditions

    Microsoft Academic Search

    Emanuel Panousis; Nofel Merbahi; Franck Clement; Andre Ricard; Mohammed Yousfi; Leberis Papageorghiou; Jean-Francis Loiseau; Olivier Eichwald; Bernard Held; Nicolas Spyrou

    2009-01-01

    This paper deals with atmospheric pressure DBDs driven under unipolar and bipolar pulsed excitation, in a context of chemical reactivity in flowing afterglow conditions. The resulting discharges in air and nitrogen are examined via electrical and optical diagnostics. Then, their yield in the production of active species (ozone for the air afterglow-atomic Nitrogen and N2(A) metastables for the N2 afterglow)

  19. Transparent and Conductive ZnO Thin Films Prepared by Atmospheric-Pressure Chemical Vapor Deposition Using Zinc Acetylacetonate

    Microsoft Academic Search

    Tadatsugu Minami; Hideo Sonohara; Shinzo Takata; Hirotoshi Sato

    1994-01-01

    Highly transparent and conductive undoped and impurity-doped ZnO thin films have been prepared by atmospheric-pressure chemical vapor deposition (CVD) using Zn(C5H7O2)2 as a zinc source. A resistivity as low as 4.6×10-3 Omega · cm and an average transmittance above 85% in the visible range were obtained for undoped ZnO thin films deposited at 550°C using H2O as the oxygen source.

  20. Zno-based thin films synthesized by atmospheric pressure mist chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lu, J. G.; Kawaharamura, T.; Nishinaka, H.; Kamada, Y.; Ohshima, T.; Fujita, S.

    2007-02-01

    An atmospheric pressure mist chemical vapor deposition (mist-CVD) system has been developed to prepare zinc oxide (ZnO)-based thin films. This is a promising method for large-area deposition at low temperatures taking into account of its simplicity, inexpensiveness, and safety. Nominally pure ZnO, Al-doped n-type ZnO (ZnO:Al), and N-doped p-type ZnO (ZnO:N) thin films, as well as Zn 1-xCd xO and Zn 1-yMg yO alloy films, have been deposited by this mist-CVD system. The films deposited at the temperatures ranging from 400 to 500 °C were of an acceptable crystallinity with (0 0 2) preferential orientation and homogeneous surface. All the films exhibited high transmittance of about 90% in visible regions and dominant UV emission in the photoluminescence spectra. The n-type ZnO:Al films had a low resistivity of 1.08×10 -3 ? cm at an optimal Al content of 4 at%. The p-type conductivity was obtained in ZnO:N films annealed at higher temperatures with a resistivity of 72.8 ? cm, Hall mobility of 2.28 cm 2 V -1 s -1, and hole concentration of 3.76×10 16 cm -3, as confirmed by Hall-effect measurements. A hydrogen-assisted nitrogen-doping mechanism was proposed to answer for the realization of p-type conductivity in ZnO. The films of Zn 1-xCd xO and Zn 1-yMg yO ternary alloys were also deposited by this technique. The band gap energies, for instance, were 3.05 eV for Zn 1-xCd xO ( x=0.06), 3.28 eV for ZnO, and 3.56 eV for Zn 1-yMg yO ( y=0.11), as confirmed by the optical absorption spectra. The band gap engineering could be readily realized in the ZnO system using mist-CVD.

  1. Screening of lake sediments for emerging contaminants by liquid chromatography atmospheric pressure photoionization and electrospray ionization coupled to high resolution mass spectrometry.

    PubMed

    Chiaia-Hernandez, Aurea C; Krauss, Martin; Hollender, Juliane

    2013-01-15

    We developed a multiresidue method for the target and suspect screening of more than 180 pharmaceuticals, personal care products, pesticides, biocides, additives, corrosion inhibitors, musk fragrances, UV light stabilizers, and industrial chemicals in sediments. Sediment samples were freeze-dried, extracted by pressurized liquid extraction, and cleaned up by liquid-liquid partitioning. The quantification and identification of target compounds with a broad range of physicochemical properties (log K(ow) 0-12) was carried out by liquid chromatography followed by electrospray ionization (ESI) and atmospheric pressure photoionization (APPI) coupled to high resolution Orbitrap mass spectrometry (HRMS/MS). The overall method average recoveries and precision are 103% and 9% (RSD), respectively. The method detection limits range from 0.010 to 4 ng/g(dw), while limits of quantification range from 0.030 to 14 ng/g(dw). The use of APPI as an alternative ionization source helped to distinguish two isomeric musk fragrances by means of different ionization behavior. The method was demonstrated on sediment cores from Lake Greifensee located in northeastern Switzerland. The results show that biocides, musk fragrances, and other personal care products were the most frequently detected compounds with concentrations ranging from pg/g(dw) to ng/g(dw), whereas none of the targeted pharmaceuticals were found. The concentrations of many urban contaminants originating from wastewater correlate with the highest phosphorus input into the lake as a proxy for treatment efficiency. HRMS enabled a retrospective analysis of the full-scan data acquisition allowing the detection of suspected compounds like quaternary ammonium surfactants, the biocide triclocarban, and the tentative identification of further compounds without reference standards, among others transformation products of triclosan and triclocarban. PMID:23215447

  2. Rapid screening procedures for the hydrolysis products of chemical warfare agents using positive and negative ion liquid chromatography–mass spectrometry with atmospheric pressure chemical ionisation

    Microsoft Academic Search

    Robert W Read; Robin M Black

    1999-01-01

    Qualitative screening procedures have been developed for the rapid detection and identification of the hydrolysis products of chemical warfare agents in aqueous samples and extracts, using liquid chromatography–mass spectrometry with positive and negative atmospheric pressure chemical ionisation (APCI). Previously reported screening procedures, which used positive APCI or electrospray ionisation (ESI), were modified by using LC conditions that allowed acquisition of

  3. Quantitation of lysergic acid diethylamide in urine using atmospheric pressure matrix-assisted laser desorption\\/ionization ion trap mass spectrometry

    Microsoft Academic Search

    Meng Cui; Margaret A. McCooeye; Catharine Fraser; Zoltán Mester

    2004-01-01

    A quantitative method was developed for analysis of lysergic acid diethylamide (LSD) in urine using atmospheric pressure matrix-assisted laser desorption\\/ionization ion trap mass spectrometry (AP MALDI-ITMS). Following solid-phase extraction of LSD from urine samples, extracts were analyzed by AP MALDI-ITMS. The identity of LSD was confirmed by fragmentation of the [M + H]+ ion using tandem mass spectrometry. The quantification

  4. Real-time explosives/narcotics vapor enhancement and collection systems for use with the atmospheric pressure ionization time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    Hintze, M. Marx; Hansen, Byron L.; Heath, Russell L.

    1992-05-01

    This paper is a companion document to the Atmospheric Pressure Ionization Time-of-Flight Mass Spectrometer (API TOFMS) presentation (Lee, et al., 1992). Two significant technique challenges related to design and implementation of vapor collection systems are addressed. They are as follows: (1) freeing deposited or trapped explosive material particles or vapor; and (2) transportation of sample specimen from the pickup point to the detector. Addressed in this dissertation will be both hand-held collection and air shower booth accumulation.

  5. Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Ouazzani, Jalil; Rosenberger, Franz

    1990-01-01

    A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

  6. Application of liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry, and tandem mass spectrometry, to the analysis and identification of degradation products of chemical warfare agents

    Microsoft Academic Search

    Robin M. Black; Robert W. Read

    1997-01-01

    A qualitative screening procedure was developed for the detection of the hydrolysis and related products of chemical warfare agents using liquid chromatography-mass spectrometry with atmospheric pressure chemical ionisation. A mixed C8\\/C18 reversed-phase column gave acceptable chromatography for the range of acidic, neutral and basic analytes. Detection limits for pure standards were less than 0.2 ng injected for the simple hydrolysis

  7. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Satoshi

    2013-07-01

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  8. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    SciTech Connect

    Hamaguchi, Satoshi [Center for Atomic and Molecular Technologies, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-07-11

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  9. Evaluation of Parameters in Atmospheric-Pressure Chemical Vapor Deposition of Borophosphosilicate Glass Using Tetraethylorthosilicate and Ozone

    NASA Astrophysics Data System (ADS)

    Nishimoto, Yuko; Tokumasu, Noboru; Maeda, Kazuo

    2001-10-01

    The effective parameters for the atmospheric-pressure chemical vapor deposition (APCVD) of borophosphosilicate glass (BPSG) using tetraethylorthosilicate (TEOS) and ozone were evaluated by designing an experiment. Source efficiencies of the deposition and doping were evaluated at constant boron and phosphorus concentrations. Each parameter was also characterized in terms of uniformity and film properties, such as thermal shrinkage and wet etch rate. Interactions between boron and phosphorus were discussed in terms of the difference in influential parameters and reaction rates. The deposition was controlled by the deposition temperature and the deposition rate, which are the dominant parameters of the film quality and deposition efficiency. The balance between gas flow rate and temperature is important to improve deposition and doping uniformity.

  10. A high temperature and atmospheric pressure experimental and detailed chemical kinetic modelling study of 2-methyl furan oxidation

    PubMed Central

    Somers, Kieran P.; Simmie, John M.; Gillespie, Fiona; Burke, Ultan; Connolly, Jessica; Metcalfe, Wayne K.; Battin-Leclerc, Frédérique; Dirrenberger, Patricia; Herbinet, Olivier; Glaude, Pierre-Alexandre; Curran, Henry J.

    2013-01-01

    An experimental ignition delay time study for the promising biofuel 2-methyl furan (2MF) was performed at equivalence ratios of 0.5, 1.0 and 2.0 for mixtures of 1% fuel in argon in the temperature range 1200–1800 K at atmospheric pressure. Laminar burning velocities were determined using the heat-flux method for mixtures of 2MF in air at equivalence ratios of 0.55–1.65, initial temperatures of 298–398 K and atmospheric pressure. A detailed chemical kinetic mechanism consisting of 2059 reactions and 391 species has been constructed to describe the oxidation of 2MF and is used to simulate experiment. Accurate reproduction of the experimental data has been obtained over all conditions with the developed mechanism. Rate of production and sensitivity analyses have been carried out to identify important consumption pathways of the fuel and key kinetic parameters under these conditions. The reactions of hydrogen atom with the fuel are highlighted as important under all experimental conditions studied, with abstraction by the hydrogen atom promoting reactivity and hydrogen atom addition to the furan ring inhibiting reactivity. This work, to the authors knowledge, is the first to combine theoretical and experimental work to describe the oxidation of any of the alkylated furans. The mechanism developed herein to describe 2MF combustion should also function as a sub-mechanism to describe the oxidation of 2,5-dimethyl furan whilst also providing key insights into the oxidation of this similar biofuel candidate. PMID:23814505

  11. Z .Thin Solid Films 392 2001 231 235 Atmospheric pressure chemical vapor deposition of

    E-print Network

    of electrochromic tungsten oxide films Roy G. Gordona,U , Sean Barryb , Jeffrey T. Bartona , Randy N.R. Broomhall oxide, WO , is a coloring layer commonly used in electrochromic windows and displays. Successful: Chemical vapor deposition; Tungsten; Oxides; Electrochromism 1. Introduction Tungsten oxide is a key

  12. Effect of Hydrogen in Size-Limited Growth of Graphene by Atmospheric Pressure Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Haoran; Zhang, Yanhui; Wang, Bin; Chen, Zhiying; Sui, Yanping; Zhang, Yaqian; Tang, Chunmiao; Zhu, Bo; Xie, Xiaoming; Yu, Guanghui; Jin, Zhi; Liu, Xinyu

    2015-01-01

    Analysis of graphene domain synthesis explains the main graphene growth process. Size-limited graphene growth caused by hydrogen is studied to achieve efficient graphene synthesis. Graphene synthesis on Cu foils via the chemical vapor deposition method using methane as carbon source is limited by high hydrogen concentration. Results indicate that hydrogen affects graphene nucleation, the growth rate, and the final domain size. Considering the role of hydrogen as both activator and etching reagent, we build a model to explain the cause of this low graphene growth rate for high hydrogen partial pressure. A two-step method is proposed to control the graphene nucleation and growth rate separately. Half the time is required to obtain similar domain size compared with single-step synthesis, indicating improved graphene synthesis efficiency. The change of the partial pressure and transmission time between the two steps is a factor that cannot be ignored to control the graphene growth.

  13. Simulation of Chemical Reactions of an Atmospheric Pressure DBD using Graphics Processing Unit

    NASA Astrophysics Data System (ADS)

    Mertmann, Philipp; Rajasekaran, Priyadarshini; Bibinov, Nikita; Awakowicz, Peter; Mussenbrock, Thomas; Gebhardt, Markus

    2009-10-01

    A dielectric barrier discharge in air for biomedical applications is characterized by numerical simulations. Plasma in air produces species like NO or O3, which are of special interest for medical application due to their potential of reacting on surfaces. Optimisation of plasma conditions to produce required density of these species is simulated using different experimental parameters. Input values for the simulation are obtained by optical emission spectroscopy, current-voltage measurements and micro- photography. Solving diffusion equation considering the gain and loss of particles by plasma-chemical reactions in a transient differential equation can be parallelized very efficiently. The use of a graphics processing unit (GPU, graphics card) for calculations allows for quick solutions of this problem. Performance tests showed that the run-time could be decreased by a factor of about 240, compared to a conventional CPU and thereby from a couple of days to 25 minutes.

  14. Aircraft Performance: Atmospheric Pressure

    E-print Network

    Aircraft Performance: Atmospheric Pressure FAA Handbook of Aeronautical Knowledge Chap 10 #12 ­ 21% Oxygen ­ 1% other gases (argon, helium, etc) · Most oxygen Atmospheric Pressure;High Density Altitude (worse performance) · High elevations · Low atmospheric pressures · High

  15. IR/THz Double Resonance Spectroscopy Approach for Remote Chemical Detection at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Tanner, Elizabeth A.; Phillips, Dane J.; De Lucia, Frank C.; Everitt, Henry O.

    2013-06-01

    A remote sensing methodology based on infrared/terahertz (IR/THz) double resonance (DR) spectroscopy is shown to overcome limitations traditionally associated with either IR or THz spectroscopic approaches for detecting trace gases in an atmosphere. The applicability of IR/THz DR spectroscopy is explored by estimating the IR and THz power requirements for detecting a 100 part-per-million-meter cloud of methyl fluoride, methyl chloride, or methyl bromide at ranges up to 1km in three atmospheric windows below 0.3 THz. These prototypical molecules are used to ascertain the dependence of the DR signal-to-noise ratio on IR and THz beam power. A line-tunable CO_2 laser with 100 ps pulse duration generates a DR signature in four rotational transitions on a time scale commensurate with collisional relaxations caused by atmospheric N_2 and O_2. A continuous wave THz beam is frequency tuned to probe one of these rotational transitions so that laser-induced absorption variations in the analyte cloud are detected as temporal power fluctuations synchronized with the laser pulses. A combination of molecule-specific physics and scenario-dependent atmospheric conditions are used to predict the signal-to-noise ratio (SNR) for detecting an analyte as a function of cloud column density. A methodology is presented by which the optimal IR/THz pump/probe frequencies are identified. These estimates show the potential for low concentration chemical detection in a challenging atmospheric scenario with currently available or near term hardware components.

  16. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25507326

  17. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25420342

  18. Continuous flow atmospheric pressure laser desorption/ionization using a 6-7-µm-band mid-infrared tunable laser for biomolecular mass spectrometry.

    PubMed

    Hiraguchi, Ryuji; Hazama, Hisanao; Senoo, Kenichirou; Yahata, Yukinori; Masuda, Katsuyoshi; Awazu, Kunio

    2014-01-01

    A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6-7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6-7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O-H, C=O, CH3 and C-N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS). PMID:24937686

  19. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  20. Atmospheric pressure femtosecond laser imaging mass spectrometry

    Microsoft Academic Search

    Yves Coello; Tissa C. Gunaratne; Marcos Dantus

    2009-01-01

    We present a novel imaging mass spectrometry technique using femtosecond laser pulses to ionize the sample at atmospheric pressure and without the need of a laser-absorbing matrix. A 10 mum-resolution image of biological tissue is demonstrated.

  1. Speciation of nitrogen containing aromatics by atmospheric pressure photoionization or electrospray ionization fourier transform ion cyclotron resonance mass spectrometry

    Microsoft Academic Search

    Jeremiah M. Purcell; Ryan P. Rodgers; Christopher L. Hendrickson; Alan G. Marshall

    2007-01-01

    We determine the elemental compositions of aromatic nitrogen model compounds as well as a petroleum sample by atmospheric\\u000a pressure photoionization (APPI) and electrospray Ionization (ESI) with a 9.4 Tesla Fourier transform ion cyclotron resonance\\u000a (FT-ICR) mass spectrometer. From the double-bond equivalents calculated for the nitrogen-containing ions from a petroleum\\u000a sample, we can infer the aromatic core structure (pyridinic versus pyrrolic

  2. Use of porous graphitic carbon for the analysis of nitrate ester, nitramine and nitroaromatic explosives and by-products by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry.

    PubMed

    Tachon, Romain; Pichon, Valérie; Le Borgne, Martine Barbe; Minet, Jean-Jacques

    2007-06-22

    A new LC/MS method was developed for the analysis of sixteen different analytes including the most common organic explosives encountered in forensic investigations. The separation was achieved using a porous graphitic carbon (PGC) column with a binary gradient elution. Molecular modeling suggested a possible interpretation for the elution order of explosive compounds on PGC. The introduction of ammonium formate in the mobile phase resulted in the formation of characteristic adduct ions thus enhancing the mass spectrometric detection of nitrate ester and nitramine compounds. Atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) were compared in terms of sensitivity. The final LC/APCI-MS method allowed easy identification of investigated compounds with limits of detection ranging from 0.04 to 1.06 ng/microl. The analysis of simulated forensic samples confirmed the performance of the method. PMID:17451723

  3. Negative atmospheric pressure chemical ionisation low-energy collision activation mass spectrometry for the characterisation of flavonoids in extracts of fresh herbs

    Microsoft Academic Search

    Ulla Justesen

    2000-01-01

    The flavonoid composition of commonly eaten fresh herbs such as dill, oregano and parsley was analysed by combined LC, MS and low-energy collision induced dissociation (CID) MS–MS. Negative atmospheric pressure chemical ionisation (APCI) MS and MS–MS were used to provide molecular mass information and product-ion spectra of the glycosyl compounds. The most prominent fragment was found to arise from the

  4. Analysis of intact bacteriohopanepolyols from methanotrophic bacteria by reversed-phase high-performance liquid chromatography–atmospheric pressure chemical ionisation mass spectrometry

    Microsoft Academic Search

    Helen M. Talbot; Diane F. Watson; J. Colin Murrell; James F. Carter; Paul Farrimond

    2001-01-01

    Direct detection of most intact biohopanoids is not possible using conventional GC–MS techniques due to their highly functionalised and amphiphilic nature. Here we report the application of a new reversed-phase high-performance liquid chromatography method for the direct analysis of acetylated, intact bacteriohopanepolyols in solvent extracts of methanotrophic bacteria. Atmospheric pressure chemical ionisation mass spectrometric detection provides structural information relating to

  5. Two-temperature chemically non-equilibrium modelling of high-power Ar N2 inductively coupled plasmas at atmospheric pressure

    Microsoft Academic Search

    Yasunori Tanaka

    2004-01-01

    A two-dimensional thermal and chemical non-equilibrium model was developed for high-power Ar-N2 inductively coupled plasmas (ICPs) at atmospheric pressure, which are conventionally assumed to be under local thermal equilibrium condition. The energy conservation equation of electrons was treated separately from that of heavy particles. These equations consider reaction heat effects and energy transfer between electrons and heavy particles as well

  6. On OH production in water containing atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter; Schram, Daan C.

    2010-08-01

    In this paper radical production in atmospheric pressure water containing plasmas is discussed. As OH is often an important radical in these discharges the paper focuses on OH production. Besides nanosecond pulsed coronas and diffusive glow discharges, several other atmospheric pressure plasmas which are of interest nowadays have a typical electron temperature in the range 1-2 eV and an ionization degree of 10-5-10-4. These properties are quite different from the typical plasma properties known from low pressure gas discharges. In the plasma physics literature OH production is primarily ascribed to be due to electron, metastable induced or thermal dissociation of water, processes which are dominant in (low pressure) gas discharges and in combustion and hot flames. It is shown in this paper that for several atmospheric pressure plasmas also dissociative recombination can be an effective method of OH radical production. Several examples are presented in detail. This paper provides a basic framework for OH production in atmospheric pressure plasmas and shows that accurate knowledge of ne, Te, Tg, the dominant ionic species, radical and neutral species are indispensable to obtain a complete view on the chemical kinetics in these challenging complex atmospheric pressure plasmas. A few relevant plasma diagnostics together with their limitations are also briefly discussed in this context.

  7. Quantitative bioanalysis of quinine by atmospheric pressure-matrix assisted laser desorption/ionization mass spectrometry combined with dynamic drop-to-drop solvent microextraction.

    PubMed

    Shrivas, Kamlesh; Wu, Hui-Fen

    2007-12-19

    Dynamic drop-to-drop solvent microextraction (DDSME) combined with atmospheric pressure-matrix assisted laser desorption/ionization mass spectrometry (AP-MALDI/MS) has been successfully applied on the bioanalysis of quinine using micro liter volume (30 microL) of human urine and plasma samples. The method is based on the movement of aqueous phase (AP) in and out of the microsyringe, which increases the transfer and diffusion rate of the quinine drug from aqueous phase to organic phase (OP). The optimization parameters including the effect of solvent selection, number of samplings, sampling volume, volume of aqueous phase, volume of organic phase, addition of salt and pH were investigated for obtaining higher extraction efficiency of the analyte. The limits of detections (LODs) of quinine, using the dynamic DDSME/AP-MALDI/MS in urine and plasma samples were 0.18 and 0.24 microM, respectively. The superiority of dynamic DDSME over static DDSME and liquid-liquid extraction (LLE) was also demonstrated for the determination of quinine in aqueous solution. This method is promising in clinical application and pharmacokinetic studies, in which the availability of sample amount is extremely small. PMID:18036378

  8. Collision induced dissociation studies of protonated alcohol and alcohol--water clusters by atmospheric pressure ionization tandem mass spectrometry.: Part 2. Ethanol, propanol and butanol

    NASA Astrophysics Data System (ADS)

    Karpas, Z.; Eiceman, G. A.; Ewing, R. G.; Harden, C. S.

    1994-04-01

    Protonated clusters of alcohols, (ROH)nH+, and alcohol--water heteroclusters, (ROH)n((H2O)mH+, where R = C2H5, n-C3H7, iso-C3H7, n-C4H9, iso-C4H9, sec-C4H9 and tert-C4H9, were formed in an atmospheric pressure ionization (API) corona discharge source, through proton transfer and displacement ion--molecule reactions with (H2O)nH+. The cluster ions were then subjected to collision induced dissociation (CID) in a tandem mass spectrometer (API-MS--MS). Stabilities of the clusters were examined through cluster size distribution analysis and CID reaction channels. The results gave insights about the structure and energetics of the clusters. The heteroclusters demonstrated a strong preference for water elimination over alcohol elimination, indicating that the alcohol moiety was the favored protonation site. The CID results indicated that in the heteroclusters water ligands were near the periphery of a chain, along which water and alcohol molecules were hydrogen bonded. This structural model could rationalize product ion formation through a single hydrogen bond cleavage for mild CID conditions and through breaking of two hydrogen bonds or a single bond after proton migration along the chain under enhanced fragmentation conditions. CID of protonated alcohols showed differences in the cleavage of C---O vs. O---H+ bonds, as well as variance in product ion distributions in the alcohols.

  9. Influence of the pre-ionization background and simulation of the optical emission of a streamer discharge in preheated air at atmospheric pressure between two point electrodes

    NASA Astrophysics Data System (ADS)

    Bourdon, A.; Bonaventura, Z.; Celestin, S.

    2010-06-01

    This paper presents simulations of positive and negative streamers propagating between two point electrodes in preheated air at atmospheric pressure. As many discharges have occurred before the simulated one, seed charges are taken into account in the interelectrode gap. First, for a pre-ionization background of 109 cm-3, we have studied the influence of the data set used for transport parameters and reaction rates for air on the simulation results. We have compared results obtained in 1997 using input parameters from Morrow and Lowke and from Kulikovsky. Deviations as large as 20% of streamer characteristics (i.e. electric field in the streamer head and body, streamer velocity, streamer radius, streamer electron density) have been observed for this point-to-point configuration. Second, we have studied the influence of the pulsed voltage frequency on the discharge structure. For the studied discharge regime, a change in the applied voltage frequency corresponds to a change in the pre-ionization background. In this work, we have considered a wide range of pre-ionization values from 104 and up to 109 cm-3. We have noted that the value of the pre-ionization background has a small influence on the electron density, electric field and location of the negative streamer head. Conversely, it has a significant influence on the positive streamer characteristics. Finally, we have compared instantaneous and time-averaged optical emissions of the three band systems of N2 and N_2^+ (1PN2, 2PN2 and 1NN_2^+ ) during the discharge propagation. We have shown that the emission of the 2PN2 is the strongest of the three bands, in agreement with experimental observations. It is interesting to note that even with a short time averaging of a few nanoseconds, which corresponds to currently used instruments, the structure of the time-averaged emission of the 2PN2 is different from the instantaneous one and shows negative and positive streamers with smaller radial expansions and more diffuse streamer heads.

  10. Liquid sampling-atmospheric pressure glow discharge (LS-APGD) ionization source for elemental mass spectrometry: preliminary parametric evaluation and figures of merit.

    PubMed

    Quarles, C Derrick; Carado, Anthony J; Barinaga, Charles J; Koppenaal, David W; Marcus, R Kenneth

    2012-01-01

    A new, low-power ionization source for the elemental analysis of aqueous solutions has recently been described. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) source operates at relatively low currents (<20 mA) and solution flow rates (<50 ?L min(-1)), yielding a relatively simple alternative for atomic mass spectrometry applications. The LS-APGD has been interfaced to what is otherwise an organic, LC-MS mass analyzer, the Thermo Scientific Exactive Orbitrap without any modifications, other than removing the electrospray ionization source supplied with that instrument. A glow discharge is initiated between the surface of the test solution exiting a glass capillary and a metallic counter electrode mounted at a 90° angle and separated by a distance of ~5 mm. As with any plasma-based ionization source, there are key discharge operation and ion sampling parameters that affect the intensity and composition of the derived mass spectra, including signal-to-background ratios. We describe here a preliminary parametric evaluation of the roles of discharge current, solution flow rate, argon sheath gas flow rate, and ion sampling distance as they apply on this mass analyzer system. A cursive evaluation of potential matrix effects due to the presence of easily ionized elements indicate that sodium concentrations of up to 50 ?g mL(-1) generally cause suppressions of less than 50%, dependant upon the analyte species. Based on the results of this series of studies, preliminary limits of detection (LOD) have been established through the generation of calibration functions. While solution-based concentration LOD levels of 0.02-2 ?g mL(-1) are not impressive on the surface, the fact that they are determined via discrete 5 ?L injections leads to mass-based detection limits at picogram to single-nanogram levels. The overhead costs associated with source operation (10 W d.c. power, solution flow rates of <50 ?L min(-1), and gas flow rates <10 mL min(-1)) are very attractive. While further optimization in the source design is suggested here, it is believed that the LS-APGD ion source may present a practical alternative to inductively coupled plasma sources typically employed in elemental mass spectrometry. PMID:21910014

  11. Atmospheric pressure femtosecond laser imaging mass spectrometry.

    PubMed

    Coello, Yves; Jones, A Daniel; Gunaratne, Tissa C; Dantus, Marcos

    2010-04-01

    A novel atmospheric pressure imaging mass spectrometry approach that offers improved lateral resolution (10 microm) using near-infrared femtosecond laser pulses for nonresonant desorption and ionization of sample constituents without the need of a laser-absorbing matrix is demonstrated. As a proof of concept the method was used to image a two-chemical pattern in paper. To demonstrate the ability of the approach to analyze biological tissue, a monolayer of onion epidermis was imaged allowing the chemical visualization of individual cells using mass spectrometry at ambient conditions for the first time. As the spatial resolution is currently limited by the limit of detection of the setup (approximately 500 fmol limit of detection for citric acid), improvements in sensitivity will increase the achievable spatial resolution. PMID:20210322

  12. Development and validation of sensitive method for determination of serum cotinine in smokers and nonsmokers by liquid chromatography\\/atmospheric pressure ionization tandem mass spectrometry

    Microsoft Academic Search

    John T. Bernert; Wayman E. Turner; James L. Pirkle; Connie S. Sosnoff; James R. Akins; Mary K. Waldrep; Qinghong Ann; Thomas R. Covey; Wanda E. Whitfield; Elaine W. Gunter; Barbara B. Miller; Donald G. Patterson; Larry L. Needham; W. Harry; Eric J. Sampson

    We describe a sensitive and specific method for measur- ing cotinine in serum by HPLC coupled to an atmo- spheric pressure chemical ionization tandem mass spec- trometer. This method can analyze 100 samples\\/day on a routine basis, and its limit of detection of 50 ng\\/L makes it applicable to the analysis of samples from nonsmok- ers potentially exposed to environmental

  13. Atmospheric pressure laser desorption/ionization using a 6-7?µm-band mid-infrared tunable laser and liquid water matrix.

    PubMed

    Hiraguchi, Ryuji; Hazama, Hisanao; Masuda, Katsuyoshi; Awazu, Kunio

    2015-01-01

    Due to the characteristic absorption peaks in the IR region, various molecules can be used as a matrix for infrared matrix-assisted laser desorption/ionization (IR-MALDI). Especially in the 6-7?µm-band IR region, solvents used as the mobile phase for liquid chromatography have absorption peaks that correspond to their functional groups, such as O-H, C=O, and CH3. Additionally, atmospheric pressure (AP) IR-MALDI, which is applicable to liquid-state samples, is a promising technique to directly analyze untreated samples. Herein we perform AP-IR-MALDI mass spectrometry of a peptide, angiotensin II, using a mid-IR tunable laser with a tunable wavelength range of 5.50-10.00?µm and several different matrices. The wavelength dependences of the ion signal intensity of [M?+?H](+) of the peptide are measured using a conventional solid matrix, ?-cyano-4-hydroxycinnamic acid (CHCA) and a liquid matrix composed of CHCA and 3-aminoquinoline. Other than the O-H stretching and bending vibration modes, the characteristic absorption peaks are useful for AP-IR-MALDI. Peptide ions are also observed from an aqueous solution of the peptide without an additional matrix, and the highest peak intensity of [M?+?H](+) is at 6.00?µm, which is somewhat shorter than the absorption peak wavelength of liquid water corresponding to the O-H bending vibration mode. Moreover, long-lasting and stable ion signals are obtained from the aqueous solution. AP-IR-MALDI using a 6-7?µm-band IR tunable laser and solvents as the matrix may provide a novel on-line interface between liquid chromatography and mass spectrometry. PMID:25601676

  14. Evaluation of the operating parameters of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) ionization source for elemental mass spectrometry.

    PubMed

    Zhang, Lynn X; Manard, Benjamin T; Konegger-Kappel, Stefanie; Kappel, Stefanie Konegger; Marcus, R Kenneth

    2014-11-01

    The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as an ionization source for elemental analysis with an interdependent, parametric evaluation regarding sheath/cooling gas flow rate, discharge current, liquid flow rate, and the distance between the plasma and the sampling cone of the mass spectrometer. In order to better understand plasma processes (and different from previous reports), no form of collision/reaction processing was performed to remove molecular interferents. The evaluation was performed employing five test elements: cesium, silver, lead, lanthanum and nickel (10(-4) mol L(-1) in 1 mol L(-1) HNO3). The intensity of the atomic ions, levels of spectral background, the signal-to-background ratios, and the atomic-to-oxide/hydroxide adduct ratios were monitored in order to obtain fundamental understanding with regards to not only how each parameter effects the performance of this LS-APGD source, but also the inter-parametric effects. The results indicate that the discharge current and the liquid sampling flow rates are the key aspects that control the spectral composition. A compromise set of operating conditions was determined: sheath gas flow rate?=?0.9 L min(-1), discharge current?=?10 mA, solution flow rate?=?10 ?L min(-1), and sampling distance?=?1 cm. Limits of detection (LODs) were calculated using the SBR-RSDB (signal-to-background ratio/relative standard deviation of the background) approach under the optimized condition. The LODs for the test elementals ranged from 15 to 400 ng mL(-1) for 10 ?L injections, with absolute mass values from 0.2 to 4 ng. PMID:25002336

  15. Atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S. (Los Alamos, NM)

    1999-01-01

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  16. Chemical kinetics and reactive species in atmospheric pressure helium-oxygen plasmas with humid-air impurities

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

    2013-02-01

    In most applications helium-based plasma jets operate in an open-air environment. The presence of humid air in the plasma jet will influence the plasma chemistry and can lead to the production of a broader range of reactive species. We explore the influence of humid air on the reactive species in radio frequency (rf)-driven atmospheric-pressure helium-oxygen mixture plasmas (He-O2, helium with 5000 ppm admixture of oxygen) for wide air impurity levels of 0-500 ppm with relative humidities of from 0% to 100% using a zero-dimensional, time-dependent global model. Comparisons are made with experimental measurements in an rf-driven micro-scale atmospheric pressure plasma jet and with one-dimensional semi-kinetic simulations of the same plasma jet. These suggest that the plausible air impurity level is not more than hundreds of ppm in such systems. The evolution of species concentration is described for reactive oxygen species, metastable species, radical species and positively and negatively charged ions (and their clusters). Effects of the air impurity containing water humidity on electronegativity and overall plasma reactivity are clarified with particular emphasis on reactive oxygen species.

  17. Special issue: diagnostics of atmospheric pressure microplasmas

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

    In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of, e.g. Werner von Siemens [9], who studied a dielectric barrier discharge (DBD) in the context of ozone generation. DBD discharges often consist of numerous filamentary discharges which are inherently transient in nature and with a characteristic size similar to the dimensions of microplasmas. Several groups are investigating the stabilization of such plasma filaments to perform temporal and spatial resolved diagnostics. To this end and due to the many similar challenges for diagnostics, this type of discharge is also included in this special issue. Research on microplasmas is performed in many groups spread all over the world, and a biannual workshop is devoted to the topic. The 7th edition of this International Workshop on Microplasmas was held in Beijing in May 2013. Large research programs consisting of clusters of research labs such as in Japan, Germany, France and the USA have been producing a wealth of information available in the literature. As the editors of this special issue, we are very pleased to have attracted a collection of excellent papers from leading experts in the field covering most of the current diagnostics performed in microplasmas. As an introduction to the regular special issue papers, a review paper is included [10]. It describes the key characteristics of atmospheric pressure plasmas and microplasmas in particular, and reviews the state of the art in plasma diagnostics. Special attention has been given in this review to highlighting the issues and challenges to probe microplasmas. The regular papers cover a large range of different diagnostics including coherent anti-Stokes Raman scattering (CARS) [11], (two-photon) laser induced fluorescence ((Ta)LIF) [12, 13, 18, 24], absorption spectroscopy [13-18], optical emission spectroscopy [12, 16-21, 24], imaging [22, 23], surface diagnostics [24, 25] and mass spectrometry [26, 27]. Different aspects of microplasmas are broadly investigated from a perspective of diagnostics, modelling and applications. Diagnostics are pivotal to both the development of models and the optimization and explorat

  18. Probing new approaches using atmospheric pressure photo ionization for the analysis of brominated flame retardants and their related degradation products by liquid chromatography–mass spectrometry

    Microsoft Academic Search

    Laurent Debrauwer; Anne Riu; Majdouline Jouahri; Estelle Rathahao; Isabelle Jouanin; Jean-Philippe Antignac; Ronan Cariou; Bruno Le Bizec; Daniel Zalko

    2005-01-01

    Atmospheric pressure photo ionisation has been evaluated for the analysis of brominated flame retardants and their related degradation products by LC–MS. Degradation mixtures obtained from the photochemical degradation of tetrabromobisphenol A and decabromodiphenylether were used as model systems for the assessment of the developed methodology. Negative ion mode gave best results for TBBPA and its degradation compounds. [M?H]? ions were

  19. Metabolite localization by atmospheric pressure high-resolution scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging in whole-body sections and individual organs of the rove beetle Paederus riparius.

    PubMed

    Bhandari, Dhaka Ram; Schott, Matthias; Römpp, Andreas; Vilcinskas, Andreas; Spengler, Bernhard

    2014-11-26

    Mass spectrometry imaging provides for non-targeted, label-free chemical imaging. In this study, atmospheric pressure high-resolution scanning microprobe matrix-assisted laser desorption/ionization mass spectrometry imaging (AP-SMALDI MSI) was used for the first time to describe the chemical distribution of the defensive compounds pederin, pseudopederin, and pederon in tissue sections (16 ?m thick) of the rove beetle Paederus riparius. The whole-insect tissue section was scanned with a 20-?m step size. Mass resolution of the orbital trapping mass spectrometer was set to 100,000 at m/z 200. Additionally, organ-specific compounds were identified for brain, nerve cord, eggs, gut, ovaries, and malpighian tubules. To confirm the distribution of the specific compounds, individual organs from the insect were dissected, and MSI experiments were performed on the dissected organs. Three ganglia of the nerve cord, with a dimension of 250-500 ?m, were measured with 10-?m spatial resolution. High-quality m/z images, based on high spatial resolution and high mass accuracy were generated. These features helped to assign mass spectral peaks with high confidence. Mass accuracy of the imaging experiments was <3 ppm root mean square error, and mapping of different compound classes from a single experiment was possible. This approach improved the understanding of the biochemistry of P. riparius. Concentration differences and distributions of pederin and its analogues could be visualized in the whole-insect section. Without any labeling, we assigned key lipids for specific organs to describe their location in the body and to identify morphological structures with a specificity higher than with staining or immunohistology methods. PMID:25424178

  20. Demixing in Atmospheric-Pressure Arcs

    NASA Astrophysics Data System (ADS)

    Murphy, A. B.

    2000-10-01

    Most atmospheric-pressure arcs of industrial interest contain mixtures of gases. In arc welding, for example, mixtures of argon with helium, hydrogen, carbon dioxide or oxygen are used. Demixing is a diffusion-driven phenomenon that leads to the partial separation of the different chemical elements present in such arcs. Typically the chemical elements with lower mass and higher ionization energies are concentrated in the high-temperature regions of the arc. A two-dimensional numerical model of demixing in atmospheric-pressure free burning arcs has been developed.(A. B. Murphy, Phys. Rev. E, 55) (1997) 7473--94; J. Phys. D, 31 (1998) 3383--90. The model incorporates the combined-diffusion-coefficient treatment of diffusion, (A. B. Murphy, Phys. Rev. E, 48) (1993) 3594--604. which allows all species derived from a particular chemical element to be grouped together. Arcs in mixtures of argon with helium, hydrogen, oxygen and nitrogen have been investigated. It is predicted that demixing causes large changes in composition, up to a factor of four compared to a fully-mixed plasma. The predictions have been compared to spectroscopic measurements of argon--nitrogen, argon--helium and argon--hydrogen arcs, with generally good agreement being observed.(A. B. Murphy and K. Hiraoka, J. Phys. D, submitted.) The model has been used to obtain significant physical insights into the importance of the different demixing mechanisms, which include demixing due to partial pressure gradients, demixing due to collisional forces, demixing due to thermal diffusion, and cataphoresis. The model also allows the investigation of the effect of demixing on parameters such as arc temperature and flow, and heat flow to the electrodes. It is found that demixing can significantly alter the latter parameter, which is critical in welding applications.

  1. Thin-layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemica lionization

    SciTech Connect

    Ovchinnikova, Olga S [ORNL; Van Berkel, Gary J [ORNL

    2010-01-01

    An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high-performance thin-layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read-out resolution, detection limits, and surface type are discussed.

  2. An investigation into the optimum thickness of titanium dioxide thin films synthesized by using atmospheric pressure chemical vapour deposition for use in photocatalytic water oxidation.

    PubMed

    Hyett, Geoffrey; Darr, Jawwad A; Mills, Andrew; Parkin, Ivan P

    2010-09-10

    Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660?°C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365?nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ?200?nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation. PMID:20645333

  3. Atmospheric Pressure Chemical Vapor Deposition of High Silica SiO2-TiO2 Antireflective Thin Films for Glass Based Solar Panels

    SciTech Connect

    Klobukowski, Erik R [ORNL; Tenhaeff, Wyatt E [ORNL; McCamy, James [PPG; Harris, Caroline [PPG; Narula, Chaitanya Kumar [ORNL

    2013-01-01

    The atmospheric pressure chemical vapor deposition (APCVD) of SiO2-TiO2 thin films employing [[(tBuO)3Si]2O-Ti(OiPr)2], which can be prepared from commercially available materials, results in antireflective thin films on float glass under industrially relevant manufacturing conditions. It was found that while the deposition temperature had an effect on the SiO2:TiO2 ratio, the thickness was dependent on the time of deposition. This study shows that it is possible to use APCVD employing a single source precursor containing titanium and silicon to produce thin films on float glass with high SiO2:TiO2 ratios.

  4. Experimental Investigation of Atmospheric Pressure Nonequilibrium Plasma Chemistry for Plasma Assisted Chemical Vapor Deposition (pacvd) of Diamond Thin Films.

    NASA Astrophysics Data System (ADS)

    Baldwin, Scott Keith, Jr.

    1996-08-01

    The effects of boundary layer chemistry in atmospheric pressure plasma-assisted diamond deposition were studied. Two separate experimental facilities were used to study effects of reactor conditions on the quantity and quality of the films produced. The first facility, a radio frequency inductively coupled plasma torch, was used to map out the growth domain based on methane-to-hydrogen ratio and substrate temperature. It was found the optimal reactor conditions for this experiment were 2.0-3.0% CH_4 in H_2 and a substrate temperature of 1370-1470 K. These conditions produced well-faceted, high quality (based on Raman spectroscopy) diamond films at reasonable linear growth rates (~55 mum/hour). Growth rates up to 100 mum/hr were attained in this facility, however, Raman spectroscopy indicated the films were amorphous in nature. The second facility, a direct current plasma torch, was used to study the effect of positive substrate biasing on diamond deposition. The substrate biasing was implemented to perturb the boundary layer, gas-phase chemistry by targeting the energy addition at the highly mobile free electrons in the plasma. A factor of seven increase in growth rate was found at a maximum bias of 4.9 A/cm ^2 and 170 V as compared with the unbiased substrate case. A minimum bias current density of ~2.4 A/cm^2 was required before an enhancement of growth rate was observed. Flow field imaging in the direct current plasma torch found an increase in the H_{ alpha} and H_{beta } emission from the boundary layer region with increasing substrate bias. An increase in the excitation temperature, T_{alphabeta }, was observed with increasing bias and proximity to the deposition surface. Modifications to a computational model used to simulate the diamond growth process were performed to include the effects of electron-catalyzed chemistry in the gas -phase. It was determined that both electron impact dissociation of molecular hydrogen and hydrocarbon species are needed in order to predict the experimentally observed increase in diamond growth rate during substrate biasing. The electron -catalyzed chemistry inhibits recombination of the radical species as they are transported through the boundary layer. This results in elevated concentrations of radical species at the growth surface required for the deposition process and leads to the observed increase in growth rate.

  5. Radiation-induced chemical reactions of carbon monoxide and hydrogen mixture—I. Electron beam irradiation at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Sugimoto, Shun'ichi; Nishii, Masanobu; Sugiura, Toshio

    The radiation chemical reaction of Co?H 2 mixture has been studied in the pressure range from 10 4 to 1.3×10 5 Pa using 7 1. reaction vessel made of stainless. Various hydrocarbons and oxygen containing compounds such as methane, formadehyde, acetaldehyde, and methanol have been obtained as radiolytic products. The amounts and the G values of these products depended upon the irradiation conditions such as composition of reactant, total pressure, reaction temperature, and dose. It was found that the irradiation at low dose produced small amounts of trioxane and tetraoxane, which have not yet been reported in literature. The yields of these cyclic ethers increased at high pressure and at low temperature. An experiment was also made on Co?H 2 mixture containing ammonia as a cation scavenger to investigate the precursor of these products.

  6. Determination of validamycin A in agricultural food samples by solid-phase extraction combined with liquid chromatography-atmospheric pressure chemical ionisation-tandem mass spectrometry.

    PubMed

    Wang, Chuanxian; Zhang, Zhigang; Shen, Yan; Tian, Zhengan; Xu, Dunming; Han, Chao

    2015-02-15

    For the first time, a rapid, sensitive and accurate liquid chromatography-atmospheric pressure chemical ionisation-tandem mass spectrometry (LC-APCI-MS/MS) method was developed for determination of validamycin A in agricultural food samples (rice, agaric, almond, cabbage, green onion, carrot, tomato, cucumber and spinach). The validamycin A residue was extracted with methanol-water (9/1, v/v) or methanol by vortex, and a HLB solid-phase extraction cartridge was used for cleaning up the extracts. LC-APCI-MS/MS data acquisition was carried out in multiple reaction monitoring (MRM) mode. A series of matrix-matched calibration solutions ranging from 2.5 to 50ngmL(-1) were used to record calibration curve. The limit of quantification (LOQ) was 10?gkg(-1). The average recoveries, measured at three concentrations levels (10.0, 50.0, 100.0?gkg(-1)) were in the range 83.5-109.6%. The proposed method offers the best sensitivity and specificity for the routine analysis of validamycin A in agricultural food samples. PMID:25236210

  7. Identification of the double-bond position in fatty acid methyl esters by liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Vrkoslav, Vladimír; Cva?ka, Josef

    2012-10-12

    Fatty acid methyl esters (FAMEs) were analysed by reversed-phase HPLC coupled with atmospheric pressure chemical ionisation (APCI) mass spectrometry. The chromatographic separations of the FAMEs were optimised using acetonitrile or binary acetonitrile gradients and C18 or C30 columns. The gas-phase reactions of acetonitrile and unsaturated FAMEs in the APCI source provided [M+C(3)H(5)N](+·) adducts. When fragmented, these adducts yielded diagnostic ions, allowing the unambiguous localisation of double bonds. The formation and fragmentation of the acetonitrile-related adduct was utilised for the structural characterisation of the FAMEs separated by HPLC. The APCI-MS detection of FAMEs encompassed a full-spectrum scan (providing information on the number of carbons and double bonds) and a data-dependent MS/MS scan of the [M+C(3)H(5)N](+·) ions (the position of the double bonds). The utility of this approach was demonstrated using a mixture of FAMEs from blackcurrant-seed oil. All the unsaturated fatty acids known to exist in the sample were correctly identified and several others were newly discovered. In terms of sensitivity, HPLC/APCI-MS appeared to be comparable to GC/EI-MS. PMID:22591660

  8. Optical diagnostics of atmospheric pressure air plasmas

    Microsoft Academic Search

    C O Laux; T G Spence; C H Kruger; R N Zare

    2003-01-01

    Atmospheric pressure air plasmas are often thought to be in local thermodynamic equilibrium owing to fast interspecies collisional exchange at high pressure. This assumption cannot be relied upon, particularly with respect to optical diagnostics. Velocity gradients in flowing plasmas and\\/or elevated electron temperatures created by electrical discharges can result in large departures from chemical and thermal equilibrium. This paper reviews

  9. Atmospheric-pressure plasma-enhanced chemical vapor deposition of a-SiCN:H films: role of precursors on the film growth and properties.

    PubMed

    Guruvenket, Srinivasan; Andrie, Steven; Simon, Mark; Johnson, Kyle W; Sailer, Robert A

    2012-10-24

    Atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) using Surfx Atomflow(TM) 250D APPJ was utilized to synthesize amorphous silicon carbonitride coatings using tetramethyldisilizane (TMDZ) and hexamethyldisilizane (HMDZ) as the single source precursors. The effect of precursor chemistry and substrate temperature (T(s)) on the properties of a-SiCN:H films were evaluated, while nitrogen was used as the reactive gas. Surface morphology of the films was evaluated using atomic force microscopy (AFM); chemical properties were determined using Fourier transform infrared spectroscopy (FTIR); thickness and optical properties were determined using spectroscopic ellipsometry and mechanical properties were determined using nanoindentation. In general, films deposited at substrate temperature (T(s)) < 200 °C contained organic moieties, while the films deposited at T(s) > 200 °C depicted strong Si-N and Si-CN absorption. Refractive indices (n) of the thin films showed values between 1.5 and 2.0, depending on the deposition parameters. Mechanical properties of the films determined using nanoindentation revealed that these films have hardness between 0.5 GPa and 15 GPa, depending on the T(s) value. AFM evaluation of the films showed high roughness (R(a)) values of 2-3 nm for the films grown at low T(s) (<250 °C) while the films grown at T(s) ? 300 °C exhibited atomically smooth surface with R(a) of ~0.5 nm. Based on the gas-phase (plasma) chemistry, precursor chemistry and the other experimental observations, a possible growth model that prevails in the AP-PECVD of a-SiCN:H thin films is proposed. PMID:22979919

  10. Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

    USGS Publications Warehouse

    Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

    2013-01-01

    Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

  11. Influence of free-standing GaN substrate on ultraviolet light-emitting-diodes by atmospheric-pressure metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Shieh, C. Y.; Li, Z. Y.; Chiu, C. H.; Tu, P. M.; Kuo, H. C.; Chi, G. C.

    2013-03-01

    We reported the influence of free-standing (FS) GaN substrate on ultraviolet light-emitting-diodes (UV LEDs) by atmospheric-pressure metal-organic chemical vapor deposition (APMOCVD). The Raman spectrum shows the in-plane compressive stress of the GaN epitaxial structures grown on FS GaN substrate. Besides, the Raman spectrum reveals the relation between the crystal quality and the carrier localization degree in multi-quantum wells (MQWs). High resolution X-ray diffraction (HRXRD) analysis results show that the In0.025Ga0.975N/Al0.08Ga0.92N MQWs grown on FS GaN substrate has higher indium mole fraction than sapphire at the same growth conditions. The higher indium incorporation is corresponding with the red-shift 6 nm (387 nm) of the room temperature photoluminescence (PL) peak. The full widths at half maximum (FWHM) of omega-scan rocking curve in (002) and (102) reflectance on FS GaN substrate (83 arcsec and 77 arcsec) are narrower than UV LEDs grown on sapphire (288 arcsec and 446 arcsec). This superior quality may attribute to homoepitaxial growth structure and better strain relaxation in the FS GaN substrate. An anomalous temperature behavior of PL in UV LEDs designated as an S-shaped peak position dependence and W-shaped linewidth dependence indicate that exciton/carrier motion occurs via photon-assisted tunneling through localized states, what results in incomplete thermalization of localized excitons at low temperature. The Gaussian broadening parameters of carrier localization is about 16.98 meV from the temperature dependent photoluminescence (TDPL) measurement. The saturation temperature from the TDPL linewidth of UV LEDs on FS GaN substrate at about 175 K represents a crossover from a nonthermalized to thermalized energy distribution of excitons.

  12. Comparison of electrospray ionization and atmospheric chemical ionization coupled with the liquid chromatography-tandem mass spectrometry for the analysis of cholesteryl esters.

    PubMed

    Lee, Hae-Rim; Kochhar, Sunil; Shim, Soon-Mi

    2015-01-01

    The approach of two different ionization techniques including electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was tested for the analysis of cholesteryl esters (CEs). The retention time (RT), signal intensity, protonated ion, and product ion of CEs were compared between ESI and APCI. RT of CEs from both ionizations decreased with increasing double bonds, while it increased with longer carbon chain length. The ESI process generated strong signal intensity of precursor ions corresponding to [M+Na](+) and [M+NH4](+) regardless of the number of carbon chains and double bonds in CEs. On the other hand, the APCI process produced a protonated ion of CEs [M+H](+) with a weak signal intensity, and it is selectively sensitive to detect precursor ions of CEs with unsaturated fatty acids. The ESI technique proved to be effective in ionizing more kinds of CEs than the APCI technique. PMID:25873970

  13. Comparison of Electrospray Ionization and Atmospheric Chemical Ionization Coupled with the Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Cholesteryl Esters

    PubMed Central

    Lee, Hae-Rim; Kochhar, Sunil; Shim, Soon-Mi

    2015-01-01

    The approach of two different ionization techniques including electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was tested for the analysis of cholesteryl esters (CEs). The retention time (RT), signal intensity, protonated ion, and product ion of CEs were compared between ESI and APCI. RT of CEs from both ionizations decreased with increasing double bonds, while it increased with longer carbon chain length. The ESI process generated strong signal intensity of precursor ions corresponding to [M+Na]+ and [M+NH4]+ regardless of the number of carbon chains and double bonds in CEs. On the other hand, the APCI process produced a protonated ion of CEs [M+H]+ with a weak signal intensity, and it is selectively sensitive to detect precursor ions of CEs with unsaturated fatty acids. The ESI technique proved to be effective in ionizing more kinds of CEs than the APCI technique.

  14. The application of gas chromatography/atmospheric pressure chemical ionisation time-of-flight mass spectrometry to impurity identification in Pharmaceutical Development.

    PubMed

    Bristow, Tony; Harrison, Mark; Sims, Martin

    2010-06-15

    Accurate mass measurement (used to determine elemental formulae) is an essential tool for impurity identification in pharmaceutical development for process understanding. Accurate mass liquid chromatography/mass spectrometry (LC/MS) is used widely for these types of analyses; however, there are still many occasions when gas chromatography (GC)/MS is the appropriate technique. Therefore, the provision of robust technology to provide accurate mass GC/MS (and GC/MS/MS) for this type of activity is essential. In this report we describe the optimisation and application of a newly available atmospheric pressure chemical ionisation (APCI) interface to couple GC to time-of-flight (TOF) MS.To fully test the potential of the new interface the APCI source conditions were optimised, using a number of standard compounds, with a variety of structures, as used in synthesis at AstraZeneca. These compounds were subsequently analysed by GC/APCI-TOF MS. This study was carried out to evaluate the range of compounds that are amenable to analysis using this technique. The range of compounds that can be detected and characterised using the technique was found to be extremely broad and include apolar hydrocarbons such as toluene. Both protonated molecules ([M + H](+)) and radical cations (M(+.)) were observed in the mass spectra produced by APCI, along with additional ion signals such as [M + H + O](+).The technique has been successfully applied to the identification of impurities in reaction mixtures from organic synthesis in process development. A typical mass accuracy of 1-2 mm/zunits (m/z 80-500) was achieved allowing the reaction impurities to be identified based on their elemental formulae. These results clearly demonstrate the potential of the technique as a tool for problem solving and process understanding in pharmaceutical development. The reaction mixtures were also analysed by GC/electron ionisation (EI)-MS and GC/chemical ionisation (CI)-MS to understand the capability of GC/APCI-MS relative to these two firmly established techniques. PMID:20486265

  15. An atmospheric pressure plasma source

    Microsoft Academic Search

    Jaeyoung Park; I. Henins; H. W. Herrmann; G. S. Selwyn; J. Y. Jeong; R. F. Hicks; D. Shim; C. S. Chang

    2000-01-01

    An atmospheric pressure plasma source operated by radio frequency power has been developed. This source produces a unique discharge that is volumetric and homogeneous at atmospheric pressure with a gas temperature below 300 °C. It also produces a large quantity of oxygen atoms, ~5×1015 cm-3, which has important value for materials applications. A theoretical model shows electron densities of 0.2-2×1011

  16. Constraints on Early Mars atmospheric pressure

    E-print Network

    Kite, Edwin

    Constraints on Early Mars atmospheric pressure from small ancient craters impactors, so impact crater size is a probe of atmospheric pressure. ebar4bar Diameter (m) Fractionofcraterssmallerthan ! Atmospheric pressure upper limit

  17. Chemical form effects on the surface ionization of lithium halides

    Microsoft Academic Search

    Tatsuya Suzuki; Hideki Iwabuchi; Kazuko Takahashi; Masao Nomura; Makoto Okamoto; Yasuhiko Fujii

    1995-01-01

    The surface ionization of lithium halides, i.e. fluoride, chloride, bromide and iodide, was studied using a mass spectrometer. In the measurements of ionization using rhenium filaments, it was found that the ionization efficiencies depend on the chemical forms of the samples. To analyze the mechanism of ionization, direct ionization by dissociative ionization is introduced in the present work. The ionization

  18. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S. (Los Alamos, NM); Henins, Ivars (Los Alamos, NM); Babayan, Steve E. (Huntington Beach, CA); Hicks, Robert F. (Los Angeles, CA)

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  19. Biomedical applications and diagnostics of atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Petrovi?, Z. Lj; Pua?, N.; Lazovi?, S.; Maleti?, D.; Spasi?, K.; Malovi?, G.

    2012-03-01

    Numerous applications of non-equilibrium (cold, low temperature) plasmas require those plasmas to operate at atmospheric pressure. Achieving non-equilibrium at atmospheric pressure is difficult since the ionization growth is very fast at such a high pressure. High degree of ionization on the other hand enables transfer of energy between electrons and ions and further heating of the background neutral gas through collisions between ions and neutrals. Thus, all schemes to produce non-equilibrium plasmas revolve around some form of control of ionization growth. Diagnostics of atmospheric pressure plasmas is difficult and some of the techniques cannot be employed at all. The difficulties stem mostly from the small size. Optical emission spectroscopy and laser absorption spectroscopy require very high resolution in order to resolve the anatomy of the discharges. Mass analysis is not normally applicable for atmospheric pressure plasmas, but recently systems with triple differential pumping have been developed that allow analysis of plasma chemistry at atmospheric pressures which is essential for numerous applications. Application of such systems is, however, not free from problems. Applications in biomedicine require minimum heating of the ambient air. The gas temperature should not exceed 40 °C to avoid thermal damage to the living tissues. Thus, plasmas should operate at very low powers and power control is essential. We developed unique derivative probes that allow control of power well below 1 W and studied four different sources, including dielectric barrier discharges, plasma needle, atmospheric pressure jet and micro atmospheric pressure jet. The jet operates in plasma bullet regime if proper conditions are met. Finally, we cover results on treatment of bacteria and human cells as well as treatment of plants by plasmas. Localized delivery of active species by plasmas may lead to a number of medical procedures that may also involve removal of bacteria, fungi and spores.

  20. Microwave Atmospheric-Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Flower, D. A.; Peckham, G. E.; Bradford, W. J.

    1986-01-01

    Report describes tests of microwave pressure sounder (MPS) for use in satellite measurements of atmospheric pressure. MPS is multifrequency radar operating between 25 and 80 GHz. Determines signal absorption over vertical path through atmosphere by measuring strength of echoes from ocean surface. MPS operates with cloud cover, and suitable for use on current meteorological satellites.

  1. Growth rate enhancement of heavy n- and p-type doped silicon deposited by atmospheric-pressure chemical vapor deposition at low temperatures

    SciTech Connect

    Agnello, P.D.; Sedgwick, T.O.; Cotte, J. (IBM T.J. Watson Research Center, Yorktown Heights, NY (United States))

    1993-09-01

    N and p-Type doping of epitaxially grown Si over the temperature range from 850 C to as low as 550 C was investigated in an atmospheric pressure reactor. P, As, and B could be incorporated into single-crystal silicon at levels exceeding the solid solubility at growth temperatures to levels greater than 1 [times] 10[sup 20]/cm[sup 3]. Remarkably, each of the hydride dopant sources, PH[sub 3], AsH[sub 3], and B[sub 2]H[sub 6], dramatically enhanced the growth rate of Si from dichlorosilane (DCS) at lower temperatures. Such results are unprecedented for the growth of Si from dichlorosilane (DCS) at lower temperature. Such results are unprecedented for the growth of Si from dichlorosilane ((DCS) which has been restricted to higher growth temperatures until recently) and for growth from SiH[sub 4] (which has been practiced over a wide range of temperatures). Growth was carried out primarily from DCS in H[sub 2] carrier gas, although some experiments utilizing SiH[sub 4] were performed, in order to explore the mechanisms responsible for growth rate enhancement of doped films. Instrumental in achieving these results has been the ultraclean, load-locked atmospheric pressure reactor, which permits high-quality epitaxial growth at temperatures no previously obtainable with DCS. Thus utilizing conventional Si and dopant sources in an unconventional regime, doping behavior suitable for advanced device structures was obtained.

  2. Sub-nanosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3

    E-print Network

    Boyer, Edmond

    Sub-nanosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3 u propagation in atmospheric pressure air is presented. With tens-of-picoseconds and tens-of-microns precision by streamer-head electrons. 1 Introduction Streamer in atmospheric pressure air is a contracted ionizing wave

  3. Picosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3

    E-print Network

    Boyer, Edmond

    Picosecond delays of light emitted by streamer in atmospheric pressure air: analysis of N2(C3 u occurring dur- ing the positive streamer propagation in atmospheric pressure air is presented. It is shown and motivation Streamer in atmospheric pressure air is a contracted ionizing wave that propagates into a low

  4. Development of Ion Drift-Chemical Ionization Mass Spectrometry

    E-print Network

    Development of Ion Drift-Chemical Ionization Mass Spectrometry Edward C. Fortner, Jun Zhao An ion drift-chemical ionization mass spectrometry (ID- CIMS) technique has been developed to detect in laboratory kinetic investigations and field measurements. Chemical ionization mass spectrometry (CIMS) has

  5. Single drop microextraction using silver nanoparticles as electrostatic probes for peptide analysis in atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry and comparison with gold electrostatic probes and silver hydrophobic probes.

    PubMed

    Sudhir, Putty-Reddy; Shrivas, Kamlesh; Zhou, Zi-Cong; Wu, Hui-Fen

    2008-10-01

    Single drop microextraction using tetraalkylammonium bromide coated silver nanoparticles (SDME-AgNPs) prepared in toluene has been successfully applied as electrostatic affinity probes to preconcentrate peptide mixtures in biological samples prior to atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry (AP-MALDI-MS) analysis. This approach is based on the isoelectric point (pI) of peptides and surface charge of AgNPs. Using the SDME-AgNPs technique, from a peptide mixture, Met- and Leu-enkephalins (Met-enk and Leu-enk) were extracted into a droplet of toluene containing AgNPs, but not the neutral peptides (gramicidins). The best peptide extraction efficiency for SDME-AgNPs was observed with the optimized parameters: extraction time 2 min, sample agitation rate 240 rpm, and sample pH 7. The limits of detection (LODs) of the SDME-AgNPs/AP-MALDI-MS technique for Met-enk and Leu-enk peptides were 160 and 210 nM, respectively. Furthermore, the application of the technique has been shown for the analysis of peptides from a sample containing high matrix interferences such as 1% Triton X-100 and 6 M urea. Finally, this approach has been compared with the SDME-AuNPs technique and the results have clearly revealed that the SDME-AgNP affinity probe exhibits higher affinity to extract the sulfur-bearing peptide (Met-enk). We also compared this electrostatic affinity probe of AgNPs with the previously demonstrated hydrophobic affinity probe of AgNPs and found that the electrostatic probe can greatly reduce the extraction time from 1.5 h to 2 min. This is due to the fact that electrostatic attraction forces are much stronger than the hydrophobic attraction forces. Therefore, we concluded that the electrostatic affinity probe based on SDME-AgNPs coupled with AP-MALDI-MS is a high-throughput technique for the analysis of low-abundance peptides from biological samples containing complex matrices. PMID:18777509

  6. Chemical protection against ionizing radiation. Final report

    SciTech Connect

    Livesey, J.C.; Reed, D.J.; Adamson, L.F.

    1984-08-01

    The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

  7. Applications of silver nanoparticles capped with different functional groups as the matrix and affinity probes in surface-assisted laser desorption/ionization time-of-flight and atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry for rapid analysis of sulfur drugs and biothiols in human urine.

    PubMed

    Shrivas, Kamlesh; Wu, Hui-Fen

    2008-09-01

    A strategy is presented for the analysis of sulfur drugs and biothiols using silver nanoparticles (AgNPs) capped with different functional groups as the matrix and affinity probes in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) and atmospheric pressure-matrix assisted laser desorption/ionization ion trap mass spectrometry (AP-MALDI-ITMS). Biothiols adsorbed on the surface of AgNPs through covalent bonding were subjected to ultraviolet (UV) radiation that enabled desorption and ionization due to the excellent photochemical property of NPs. The proposed method has been successfully applied for the determination of cysteine and homocysteine in human urine samples using an internal standard. The limit of detection (LOD) and limit of quantification (LOQ) for cysteine and homocysteine in urine sample are 7 and 22 nM, respectively, with a relative standard deviation (RSD) of <10%. The advantages of the present method compared with the methods reported in the literature for biothiol analysis are simplicity, rapidity and sensitivity without the need for time-consuming separation and tedious preconcentration processes. Additionally, we also found that the bare AgNPs can be directly used as the matrix in MALDI-TOF MS for the analysis of sulfur drugs without the addition of an extra proton source. PMID:18720468

  8. The effect of oxygen-containing reagents on the crystal morphology and orientation in tungsten oxide thin films deposited via atmospheric pressure chemical vapour deposition (APCVD) on glass substrates.

    PubMed

    Hyett, Geoffrey; Blackman, Christopher S; Parkin, Ivan P

    2007-01-01

    Thin films of monoclinic WO3 and WO(3-x) have been synthesized by atmospheric pressure chemical vapour deposition from WCl6 and three oxygen containing precursors; water, ethanol and ethanoic anhydride. A wide variation in the colour, crystal morphology and preferred orientation of the films was observed, depending on the chosen oxygen source. In particular contrast were the films formed from WCl6 and ethanol, which were blue and had needle-like crystallites, and those formed from WCl6 and water, which were yellow and had hexagonal shaped crystallites. Studies were also undertaken to form films from WCl6, ethanol and water simultaneously, in which the ratio of ethanol to water was varied, and this led to films in which the crystal morphology and orientation could be controlled. PMID:17955818

  9. Application of Ni-63 photo and corona discharge ionization for the analysis of chemical warfare agents and toxic wastes

    NASA Technical Reports Server (NTRS)

    Stach, J.; Adler, J.; Brodacki, M.; Doring, H.-R.

    1995-01-01

    Over the past decade, advances in instrumental design and refinements in the understanding of ion molecule reactions at atmospheric pressure enabled the application of Ion Mobility Spectrometry (IMS) as a simple inexpensive and sensitive analytical method for the detection of organic trace compounds. Positive and negative gas-phase ions for ion mobility spectrometry have been produced by a variety of methods, including photo-ionization, laser multi photon ionization, surface ionization, corona discharge ionization. The most common ion source used in ion mobility spectrometry is a radioactive Ni-63 foil which is favored due to simplicity, stability, convenience, and high selectivity. If reactant ions like (H2O(n)H)(+) or (H2O(n)O2)(-) dominate in the reaction region, nearly all kinds of compounds with a given proton or electron affinity; are ionized. However, the radioactivity of the Ni-63 foil is one disadvantage of this ion source that stimulates the development and application of other ionization techniques. In this paper, we report analyses of old chemical warfare agents and toxic wastes using Bruker RAID ion mobility spectrometers. Due to the modular construction of the measuring cell, the spectrometers can be equipped with different ion sources. The combined use of Ni-63, photo- and corona discharge ionization allows the identification of different classes of chemical compounds and yields in most cases comparable results.

  10. GC/MS on an LC/MS instrument using atmospheric pressure photoionization

    NASA Astrophysics Data System (ADS)

    McEwen, Charles N.

    2007-01-01

    Atmospheric pressure (AP) GC/MS was first introduced by Horning et al. [E.C. Horning, M.G. Horning, D.I. Carroll, I. Dzidic, R.N. Stillwell, Anal. Chem. 45 (1973) 936] using 63Ni as a beta-emitter for ionization. Because, at the time special instrumentation was required, the technique was only applied with consistency to negative ion environmental studies where high sensitivity was required [T. Kinouchi, A.T.L. Miranda, L.G. Rushing, F.A. Beland, W.A. Korfmacher, J. High Resolut. Chromatogr., Chromatogr. Commun. 13 (1990) 281]. Currently, AP ion sources are commonly available on LC/MS instruments and recently a method was reported for converting an AP-LC/MS ion source to a combination AP-LC/MS:GC/MS source [C.N. McEwen, R.G. McKay, J. Am. Soc. Mass Spectrom. 16 (2005) 1730]. Here, we report the use of atmospheric pressure photoionization (APPI) with GC/MS and compare this to AP chemical ionization (APCI) GC/MS and electron ionization (EI) GC/MS. Using a nitrogen purge gas, we observe excellent chromatographic resolution and abundant molecular M+ and MH+ ions as well as structurally significant fragment ions. Comparison of a 9.8 eV UV lamp with a 10.6 eV lamp, as expected, shows that the higher energy lamp gives more universal ionization and more fragment ions than the lower energy lamp. While there are clear differences in the fragment ions observed by APPI-MS versus EI-MS, there are also similarities. As might be expected from the ionization mechanism, APPI ionization is similar to low energy EI. These odd electron fragment ions are useful in identifying unknown compounds by comparison to mass spectra in computer libraries.

  11. Negative ion-atmospheric pressure photoionization-mass spectrometry

    Microsoft Academic Search

    Tiina J. Kauppila; Tapio Kotiaho; Risto Kostiainen; Andries P. Bruins

    2004-01-01

    The ionization mechanism in the novel atmospheric pressure photoionization mass spectrometry (APPI-MS) in negative ion mode\\u000a was studied thoroughly by the analysis of seven compounds in 17 solvent systems. The compounds possessed either gas-phase\\u000a acidity or positive electron affinity, whereas the solvent systems had different polarities and gas-phase acidities and some\\u000a of them positive electron affinities. The analytes that possessed

  12. Microwave heating systems for atmospheric pressure: Nonequilibrium plasmas

    Microsoft Academic Search

    G. E. Guest; R. A. Dandl

    1989-01-01

    Nonequilibrium plasma-chemical processing is attracting increasing interest because of the possibility of creating mixtures of active species that would not be available in thermal equilibrium. For significant throughput of reactants it would be advantageous to create nonequilibrium plasmas in large volumes of atmospheric-pressure mixtures of gases. Techniques for accomplishing this are very limited at present. Here we describe a novel

  13. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    NASA Technical Reports Server (NTRS)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  14. TOPICAL REVIEW: Non-thermal atmospheric pressure discharges

    Microsoft Academic Search

    A. Fridman; A. Chirokov; A. Gutsol

    2005-01-01

    There has been considerable interest in non-thermal atmospheric pressure discharges over the past decade due to the increased number of industrial applications. Diverse applications demand a solid physical and chemical understanding of the operational principals of such discharges. This paper focuses on the four most important and widely used varieties of non-thermal discharges: corona, dielectric barrier, gliding arc and spark

  15. [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. PMID:25055654

  16. Quantitative Radar REMPI measurements of methyl radicals in flames at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Zhang, Zhili; Ombrello, Timothy M.; Katta, Viswanath R.

    2013-05-01

    Spatially resolved quantitative measurements of methyl radicals (CH3) in CH4/air flames at atmospheric pressure have been achieved using coherent microwave Rayleigh scattering from Resonance enhanced multi-photon ionization, Radar REMPI. Relative direct measurements of the methyl radicals were conducted by Radar REMPI via the two-photon resonance of the 3p2 A2^' ' } 000 state and subsequent one-photon ionization. Due to the proximity of the argon resonance state of 2 s 22 p 54 f [7 /2, J = 4](4+1 REMPI by 332.5 nm) with the CH3 state of 3p2 A2^' ' } 000 (2+1 REMPI by 333.6 nm), in situ calibration with argon was performed to quantify the absolute concentration of CH3. The REMPI cross sections of CH3 and argon were calculated based on time-dependent quantum perturbation theory. The measured CH3 concentration in CH4/air flames was in good agreement with numerical simulations performed using detailed chemical kinetics. The Radar REMPI method has shown great flexibility for spatial scanning, large signal-to-noise ratio for measurements at atmospheric pressures, and significant potential to be straightforwardly generalized for the quantitative measurements of other radicals and intermediate species in practical and relevant combustion environments.

  17. Real-time Measurement of Secondary Organic Aerosols From The Photo-oxidation of Toluene Using Atmospheric Pressure Chemical Ionisation Tandem Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Collin, F.; Arias, M. C.; Merritt, J. V.; Hastie, D. R.

    A system has been developed to study the chemical composition of secondary or- ganic aerosol (SOA) from the photo-oxidation of hydrocarbons using real-time atmo- spheric pressure chemical ionisation triple quadrupole mass spectrometry (APCI/MS- MS) analysis. To complement existing work with a smog chamber, a two-litre dynamic reaction cell has been built. This has a residence time of around two minutes (instead of several hours for smog chamber experiments), thus permitting on-line analysis. Sample gases are introduced into the air stream and irradiated by a 1000 W xenon arc lamp. Af- ter dilution, some of the mixture from the reaction cell is introduced in the MS ion source via a heated probe, with the particle number density being determined by a condensation nucleus counter on the remainder. The focus so far has been on SOA from the photo-oxidation of toluene by HO radicals in presence of NO, with the HO radicals being generated by the photolysis of Isopy- lNitrite (IPN). Prior to performing analyses on the SOA, target compounds (detected in the particulate phase in other studies) were selected and three ions designated to make a fingerprint for each compound. Finally, by using either a denuder, a granu- lar bed diffusion battery or a filter, both gas and particulate phases have been studied independently and compared. Preliminary results show that a number of target compounds, such as methylglyoxylic acid, benzaldehyde or cresol, have been detected in both gas and particulate phases. Most of these compounds appear to be present mainly in the gas phase. An exhaustive identification of organic compounds is a part of the on-going work.

  18. Intense and highly energetic atmospheric pressure plasma jet arrays

    NASA Astrophysics Data System (ADS)

    Furmanski, John Ryan

    This thesis documents the efforts taken to produce highly ionized and concentrated atmospheric pressure plasma using an arrayed atmospheric pressure plasma jet (APPJ) system. The honeycomb-shaped array features seven plasma jets operating in close enough proximity to one another to exhibit jet-to-jet coupling behavior. Optimal gas flow rates for the system were determined and intense plasma plumes composed of argon and/or helium are generated. Optical emission spectroscopy was employed to observe the charged particles responsible for the emissions of each gas discharge and APPJ operation mode. Plasma etching of indium tin oxide glass was conducted to verify the highly energetic properties of a plasma generated using two dissimilar gases, in order to confirm the possibility of plasma coupling between them.

  19. BIOLOGICALAPPLICATIONS OF ATMOSPHERIC PRESSURE DIELECTRIC BARRIER DISCHARGES

    E-print Network

    Paris-Sud XI, Université de

    ABSTRACT. A reduction of more than 4 orders of magnitude of survivors was obtained by exposing a Bacillus Stearothermophilus spores - contaminated surface to an atmospheric pressure DBD post-discharge for 20 minutes

  20. High-performance liquid chromatography-mass spectrometry of porphyrins by using an atmospheric pressure interface.

    PubMed

    Rosell-Melé, A; Carter, J F; Maxwell, J R

    1996-09-01

    A method is described for the high-performance liquid chromatography (HPLC) mass spectrometry analysis of porphyrin mixtures by using an atmospheric pressure interface, which can operate in two modes: pneumatically assisted elecrrospray and atmospheric pressure chemical ionization (APCI). Optimization of the conditions and evaluation of spectral information has been carried out by using direct injection of free-base and metallo porphyrin standards. The most effective results were obtained using APCI. HPLC-APCI mass spectrometry analysis of the demetallated vanadyl porphyrin fraction from the Triassic Serpiano oil shale has allowed rapid characterization of the distribution; more than 50 significant components are present. The presence of trace amounts of high molecular weight (>C33) cycloalkano porphyrins indicates the occurrence of photic zone anoxia in the ancient water column. This example illustrates the potential of the approach for studies of porphyrin mixtures of environmental or biological significance, which should be applicable to other types of metallo and free-base components that can be separated by HPLC under normal or reversed-phase conditions. PMID:24203611

  1. 76 FR 17374 - Receipt of Several Pesticide Petitions Filed for Residues of Pesticide Chemicals in or on Various...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-29

    ...processed fractions is a liquid chromatography-tandem mass spectrometry (LC/MS/ MS) method. Enforcement methods...chromatography-atmosphere pressure chemical ionization/tandem mass spectrometry analytical method is available to EPA for the...

  2. Effect of Swirling Desolvation Gas Flow in an Atmospheric Pressure Ion Source

    NASA Astrophysics Data System (ADS)

    Savtchenko, Serguei; Ashgriz, Nasser; Jolliffe, Chuck; Cousins, Lisa; Gamble, Heather

    2014-09-01

    A numerical study is performed to examine the effect of introducing a swirling desolvation gas flow on the flow transport characteristics in an electrospray and an atmospheric pressure chemical ionization (APCI) system. An ion source having three coaxial tubes is considered: (1) an inner capillary tube to inject the liquid sample, (2) a center coaxial tube to provide a room temperature gas flow to nebulize the liquid, referred to as the nebulizing gas flow, and (3) an outer coaxial tube having a converging exit to supply a high temperature gas for droplet desolvation, referred to as the desolvation gas flow. The results show that a swirling desolvation gas flow reduces the dispersion of the nebulizing gas and suppresses turbulent diffusion. The effect of swirling desolvation flow on the trajectory of a range of droplet sizes emitted from a source is also considered.

  3. Effect of swirling desolvation gas flow in an atmospheric pressure ion source.

    PubMed

    Savtchenko, Serguei; Ashgriz, Nasser; Jolliffe, Chuck; Cousins, Lisa; Gamble, Heather

    2014-09-01

    A numerical study is performed to examine the effect of introducing a swirling desolvation gas flow on the flow transport characteristics in an electrospray and an atmospheric pressure chemical ionization (APCI) system. An ion source having three coaxial tubes is considered: (1) an inner capillary tube to inject the liquid sample, (2) a center coaxial tube to provide a room temperature gas flow to nebulize the liquid, referred to as the nebulizing gas flow, and (3) an outer coaxial tube having a converging exit to supply a high temperature gas for droplet desolvation, referred to as the desolvation gas flow. The results show that a swirling desolvation gas flow reduces the dispersion of the nebulizing gas and suppresses turbulent diffusion. The effect of swirling desolvation flow on the trajectory of a range of droplet sizes emitted from a source is also considered. PMID:24916800

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  5. Generation Of Atmospheric Pressure Non-Thermal Plasma By Diffusive And Constricted Discharges In Rest And Flowing Gases (Air And Nitrogen)

    NASA Astrophysics Data System (ADS)

    Akishev, Y.; Grushin, M.; Karalnik, V.; Kochetov, I.; Napartovich A.; Trushkin N.

    2010-07-01

    Weekly ionized non-thermal plasma (NTP) is of great interest for many applications because of its strong non-equilibrium state wherein an average electron energy Te exceeds markedly gas temperature Tg, i.e. electrons in the NTP are strongly overheated compared to neutral gas. Energetic electrons due to frequent collisions with the neutrals excite and dissociate effectively atoms and molecules of the plasma-forming gas that results in a creation of physically-, and bio-chemically active gaseous medium in a practically cold background gas. At present there are many kinds of plasma sources working at low and atmospheric pressure and using MW, RF, low frequency, pulsed and DC power supplies for NTP generation. The NTP at atmospheric pressure is of considerable interest for practice. A reason is that sustaining the NTP at atmospheric pressure at first allows us to avoid the use of expensive vacuum equipment and second gives opportunity to use the NTP for treatment of the exhausted gases and polluted liquids. The second opportunity cannot be realized at all with use of the NTP at low pressure. Main subject of this talk is low current atmospheric pressure gas discharges powering with DC power supplies. Plasma forming gases are air and nitrogen which are much cheaper compared to rare gases like He or Ar. Besides, great interest to molecular nitrogen as plasma forming gas is caused first of all its unique capability to accumulate huge energy in vibration, electron (metastables) and dissociated (atomic) states providing high chemical reactivity of the activated nitrogen. All active particles mentioned above have a long lifetime, and they can be therefore transported for a long distance away from place of their generation. Different current modes (diffusive and constricted) of these discharges are discussed. Experimental and numerical results on generation of chemically active species in the diffusive and constricted mode are presented. Some data on the usage of the atmospheric pressure NTP for gas cleanup, surface treatment and sterilization are given.

  6. Low-voltage back-gated atmospheric pressure chemical vapor deposition based graphene-striped channel transistor with high-? dielectric showing room-temperature mobility > 11,000 cm(2)/V·s.

    PubMed

    Smith, Casey; Qaisi, Ramy; Liu, Zhihong; Yu, Qingkai; Hussain, Muhammad Mustafa

    2013-07-23

    Utilization of graphene may help realize innovative low-power replacements for III-V materials based high electron mobility transistors while extending operational frequencies closer to the THz regime for superior wireless communications, imaging, and other novel applications. Device architectures explored to date suffer a fundamental performance roadblock due to lack of compatible deposition techniques for nanometer-scale dielectrics required to efficiently modulate graphene transconductance (gm) while maintaining low gate capacitance-voltage product (CgsVgs). Here we show integration of a scaled (10 nm) high-? gate dielectric aluminum oxide (Al2O3) with an atmospheric pressure chemical vapor deposition (APCVD)-derived graphene channel composed of multiple 0.25 ?m stripes to repeatedly realize room-temperature mobility of 11,000 cm(2)/V·s or higher. This high performance is attributed to the APCVD graphene growth quality, excellent interfacial properties of the gate dielectric, conductivity enhancement in the graphene stripes due to low tox/Wgraphene ratio, and scaled high-? dielectric gate modulation of carrier density allowing full actuation of the device with only ±1 V applied bias. The superior drive current and conductance at Vdd = 1 V compared to other top-gated devices requiring undesirable seed (such as aluminum and poly vinyl alcohol)-assisted dielectric deposition, bottom gate devices requiring excessive gate voltage for actuation, or monolithic (nonstriped) channels suggest that this facile transistor structure provides critical insight toward future device design and process integration to maximize CVD-based graphene transistor performance. PMID:23777434

  7. Mass analysis of an atmospheric pressure plasma needle discharge

    NASA Astrophysics Data System (ADS)

    Malovi?, G.; Pua?, N.; Lazovi?, S.; Petrovi?, Z.

    2010-06-01

    Mass spectrometric measurements of a plasma needle (an example of atmospheric pressure non-equilibrium plasma source) were made for neutrals and ions. The measurements were performed for the same geometry as the standard plasma needles albeit for a somewhat increased gas flow. We discuss some of the problems of performing mass analysis at atmospheric pressures. The yields of N, O and NO radicals from the plasma needle were determined for different powers of the RF source and different flow rates of working gas. Positive ions generated by the plasma needle itself were measured for the first time. Significant conversion of feed gases (nitrogen and oxygen) into radicals and ions of N and O, and NO was observed as well as depletion of atomic radicals N and O which in chemical reactions form more complex molecules. Biomedical and nanotechnology applications of atmospheric pressure plasmas require a detailed understanding of the source, and mass analysis is perhaps the best technique to focus on chemical kinetics and in many ways interaction with surfaces.

  8. Sterilization and decontamination of surfaces using atmospheric pressure plasma discharges

    SciTech Connect

    Garate, E.; Gornostaeva, O.; Alexeff, I.; Kang, W.L.

    1999-07-01

    The goal of the program is to demonstrate that an atmospheric pressure plasma discharge can rapidly and effectively sterilize or decontaminate surfaces that are contaminated with model biological and chemical warfare agents. The plasma is produced by corona discharge from an array of pins and a ground plane. The array is constructed so that various gases, like argon or helium, can be flowed past the pins where the discharge is initiated. The pin array can be biased using either DC. AC or pulsed discharges. the work done to date has focused on the sterilization of aluminum, polished steel and tantalum foil metal coupons, about 2 cm on a side and 2 mm thick, which have been inoculated with up to 10{sup 6} spores per coupon of Bacillus subtilis var niger or Bascillus stearothermorphilus. Results indicate that 5 minute exposures to the atmospheric pressure plasma discharge can reduce the viable spore count by 4 orders of magnitude. The atmospheric pressure discharge is also effective in decomposing organic phosphate compounds that are stimulants for chemical warfare agents. Details of the decomposition chemistry, by-product formation, and electrical energy consumption of the system will be discussed.

  9. Diagnostic methods used for atmospheric pressure thermal arc plasma

    NASA Astrophysics Data System (ADS)

    Tamoši?nas, A.; Valatkevi?ius, P.; Valin?ius, V.; Grigaitien?, V.; Kavaliauskas, Ž.

    2014-05-01

    Diagnostic methods used for atmospheric pressure thermal arc plasmas are presented in this paper. An experimental direct current arc plasma torch was used as a source for plasma generation at atmospheric pressure. Overheated water vapor was employed as a plasma-forming gas with an admixture of argon as a shielding gas. A couple of plasma diagnostic methods were invoked to perform the analysis of the generated plasma jet at the nozzle exhaust of the torch. Firstly, an optical emission spectroscopy method was used to determine the chemical composition of the water vapor plasma, and from the obtained spectra, the rotational and excitation temperatures were calculated roughly. Secondly, an enthalpy probe measurement was performed in order to measure the mean temperature and the velocity lengthwise and crosswise in the plasma stream.

  10. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    NASA Astrophysics Data System (ADS)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the silicon wafers in the presence of activated carbon or in a freezer at -22°C. The enhancement of adhesive bond strength and durability for carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024 was demonstrated with the atmospheric pressure helium-oxygen plasma. All surfaces studied were converted from a hydrophobic state with a water contact angle of 65° to 80° into a hydrophilic state with a water contact angle between 20° and 40° within 5 seconds of plasma exposure. X-ray photoelectron spectroscopy confirmed that the carbon atoms on the carbon-fiber/epoxy composite were oxidized, yielding 17 atom% carboxylic acid groups, 10% ketones or aldehydes and 9% alcohols. Analysis of stainless steel and aluminum by XPS illustrate oxidation of the metal surface and an increase in the concentration of hydroxyl groups in the oxide film. Following plasma activation, the total hydroxyl species concentration on stainless steel increased from 31% to 57%, while aluminum exhibited an increase from 4% to 16% hydroxyl species. Plasma activation of the surface led to an increase in bond strength of the different surfaces by up to 150% when using Cytec FM300 and FM300-2 epoxy adhesives. Wedge crack extension tests following plasma activation revealed cohesive failure percentages of 97% for carbon-fiber/epoxy composite bonded to stainless steel, and 96% for aluminum bonded to itself. The bond strength and durability of the substrates correlated with changes in the specific surface chemistry, not the wetting angle or the morphological properties of the material. This suggests that enhanced chemical bonding at the interface was responsible for the improvement in mechanical properties following plasma activation. The surface preparation of polymers and composites using atmospheric pressure plasmas is a promising technique for replacing traditional methods of surface preparation by sanding, grit blasting or peel ply. After oxygen plasma activation and joining the materials together with epoxy, one observes 100% cohesive failure within the c

  11. Atmospheric Pressure Plasma Process And Applications

    SciTech Connect

    Peter C. Kong; Myrtle

    2006-09-01

    This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmosphericpressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

  12. Determining Atmospheric Pressure Using a Water Barometer

    ERIC Educational Resources Information Center

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  13. NEGATIVE CHEMICAL IONIZATION STUDIES OF HUMAN AND FOOD CHAIN CONTAMINATION WITH XENOBIOTIC CHEMICALS

    EPA Science Inventory

    Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasm...

  14. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    NASA Astrophysics Data System (ADS)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio-temporally resolved optical emission spectroscopy (OES) gives the evolution of excited species along the trajectory of the plasma bullets. The APLTPJs' chemical composition includes short-lived species, such as He, N2, N+2 , and long-lived species, such as Hem (helium metastable), O3, NO, NO2. It is worth noting that metastable level excited atoms play an important role in promoting an enhanced chemistry along the plasma jet. Some of the APLTPJs' biomedical applications, such as dental hygiene applications and destruction of amyloid fibrils underlying Parkinson's disease, are explored along with an important discussion showing that the APLTPJs do not have a cytotoxic effect on living cells.

  15. Method for determination of acephate, methamidophos, omethoate, dimethoate, ethylenethiourea and propylenethiourea in human urine using high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

    Microsoft Academic Search

    M Angela Montesano; Anders O Olsson; Peter Kuklenyik; Larry L Needham; A S A Bradman; Dana B Barr

    2007-01-01

    Because of increasing concern about widespread use of insecticides and fungicides, we have developed a highly sensitive analytical method to quantify urine-specific urinary biomarkers of the organophosphorus pesticides acephate, methamidophos, omethoate, dimethoate, and two metabolites from the fungicides alkylenebis-(dithiocarbamate) family: ethylenethiourea and propylenethiourea. The general sample preparation included lyophilization of the urine samples followed by extraction with dichloromethane. The analytical

  16. Quantitation of the 5HT 1D agonists MK-462 and sumatriptan in plasma by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

    Microsoft Academic Search

    D. A. McLoughlin; T. V. Olah; J. D. Ellis; J. D. Gilbert; R. A. Halpin

    1996-01-01

    The 5HT1D agonist sumatriptan is efficacious in the treatment of migraines. MK-462 is a drug of the same class which is under development in our laboratories. Bioanalytical methods of high efficiency, specificity and sensitivity were required to support the preclinical and clinical programs. These assays were based on HPLC with tandem MS-MS detection. MK-462 and sumatriptan were extracted using an

  17. Plasmas Generated With Gas Mixtures at the Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Calzada, M. D.; Muñoz, J.; Rincón, R.; Jiménez, M.; Sáez, M.

    Several applications, such as metal surface nitriding, medical instrument sterilization and chemical analysis, have been developed or improved using a gas mixture as plasmogen gas. Research carried out on these subjects covers the aspect of knowing the processes that take place in plasmas which depend on the densities of the different plasma particles and their energy values. In this paper, the results obtained from the application of spectroscopic techniques for the characterization of surface wave discharges at the atmospheric pressure, generated with more than one gas type, are presented, particularly for the Ar-He, Ar-Ne and Ar-N2 plasmas.

  18. Spectroscopic diagnosis of an atmospheric-pressure waveguide-based microwave N2–Ar plasma torch

    NASA Astrophysics Data System (ADS)

    Li, Shou-Zhe; Chen, Chuan-Jie; Zhang, Xin; Zhang, Jialiang; Wang, Yong-Xing

    2015-04-01

    An atmospheric-pressure N2–Ar plasma is investigated by means of optical emission spectroscopic diagnosis concerning the variation of its fundamental parameters, electron density and plasma temperature, and concentrations of ionized molecular nitrogen, atomic nitrogen, and excited argon with the tuning variables, such as the input power and the ratio of N2 in N2–Ar mixture gas, in the discharge region of the plasma torch. Moreover, qualitative discussions are delivered with respect to the mechanisms for nitrogen dissociation and influence of the Ar component on the N2 plasma discharge at atmospheric pressure.

  19. Electron heating in radio-frequency capacitively coupled atmospheric-pressure plasmas

    SciTech Connect

    Liu, D. W.; Iza, F.; Kong, M. G. [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2008-12-29

    In atmospheric-pressure plasmas the main electron heating mechanism is Ohmic heating, which has distinct spatial and temporal evolutions in the {alpha} and {gamma} modes. In {gamma} discharges, ionizing avalanches in the sheaths are initiated not only by secondary electrons but also by metastable pooling reactions. In {alpha} discharges, heating takes place at the sheath edges and in contrast with low-pressure plasmas, close to 50% of the power absorbed by the electrons is absorbed at the edge of the retreating sheaths. This heating is due to a field enhancement caused by the large collisionality in atmospheric-pressure discharges.

  20. Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry

    E-print Network

    Vertes, Akos

    Infrared Laser Ablation Atmospheric Pressure Photoionization Mass Spectrometry Anu Vaikkinen, Washington, DC 20052, United States *S Supporting Information ABSTRACT: In this paper we introduce laser ablation atmo- spheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass

  1. Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry

    SciTech Connect

    Aranda Gonzalvo, Y.; Whitmore, T.D.; Rees, J.A.; Seymour, D.L.; Stoffels, E. [Hiden Analytical Ltd., 420 Europa Boulevard, Warrington WA5 7UN (United Kingdom); Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2006-05-15

    Fractional number density measurements for a rf plasma 'needle' operating at atmospheric pressure have been obtained using a molecular beam mass spectrometer (MBMS) system designed for diagnostics of atmospheric plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility in the form of a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a helium/air mixture. In particular, data for the conversion of atmospheric oxygen and nitrogen into nitric oxide are discussed with reference to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery.

  2. Atmospheric-pressure plasma decontamination/sterilization chamber

    DOEpatents

    Herrmann, Hans W. (Los Alamos, NM); Selwyn, Gary S. (Los Alamos, NM)

    2001-01-01

    An atmospheric-pressure plasma decontamination/sterilization chamber is described. The apparatus is useful for decontaminating sensitive equipment and materials, such as electronics, optics and national treasures, which have been contaminated with chemical and/or biological warfare agents, such as anthrax, mustard blistering agent, VX nerve gas, and the like. There is currently no acceptable procedure for decontaminating such equipment. The apparatus may also be used for sterilization in the medical and food industries. Items to be decontaminated or sterilized are supported inside the chamber. Reactive gases containing atomic and metastable oxygen species are generated by an atmospheric-pressure plasma discharge in a He/O.sub.2 mixture and directed into the region of these items resulting in chemical reaction between the reactive species and organic substances. This reaction typically kills and/or neutralizes the contamination without damaging most equipment and materials. The plasma gases are recirculated through a closed-loop system to minimize the loss of helium and the possibility of escape of aerosolized harmful substances.

  3. Optical Diagnostics On Cold Atmospheric Pressure Plasmas

    NASA Astrophysics Data System (ADS)

    Niemi, K.; Waskoenig, J.; Graham L. M.; Gans, T.

    2010-07-01

    Cold atmospheric pressure plasma jets promise high potential for temperature sensitive surface treatments in biomedicine, see e.g. Stoffels et al. (2006). Stable homogeneous low temperature plasma operation is achieved by using helium feed gas and applying radio frequency excitation. Small admixtures of molecular oxygen to the feed gas lead to the efficient generation of highly reactive oxygen radicals. A quantification of these radical densities and fluxes is not only vital for the plasma source development and fundamental understanding but crucial for the risk benefit analysis in biomedical applications. Diagnostics of atmospheric pressure plasmas are extremely challenging due to small confining structures and the collision dominated high pressure environment demanding exceptionally high spatial and temporal resolution down to microns and picoseconds. The most promising approach is active combination of advanced optical techniques and numerical simulations. Diagnostic based modelling as a method to determine absolute atomic oxygen ground state densities inside such atmospheric pressure plasmas is proposed, see e.g. Niemi et al. (2009). A one-dimensional numerical simulation yields the spatial and temporal electron dynamics and subsequently the excitation efficiency of optical emission lines which intensities are measured temporally integrated. The population dynamics of the O 3p3P (? = 844 nm) atomic oxygen state is governed by direct electron impact excitation, dissociative excitation, radiation losses, and collisional induced quenching. Absolute atomic oxygen densities are obtained through comparison with the Ar 2p1 (? = 750.4 nm) state. Results for spatial profiles and power variations are presented. An excellent quantitative agreement with independent two-photon absorption laser-induced fluorescence measurements from Knacke et al. (2008) is found.

  4. Atmospheric pressure plasma jet for decontamination purposes

    NASA Astrophysics Data System (ADS)

    Paw?at, Joanna

    2013-02-01

    Advanced oxidation processes, especially induced by non-thermal plasmas, are widely known for their high sanitation efficiency. The paper presents general overview of atmospheric pressure plasma jet (APPJ) reactors for bactericidal decontamination purposes. In the conclusion part, the basic requirements for APPJ as a tool for biomedical applications including the treatment of living tissues are highlighted. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  5. MY NASA DATA: Atmospheric Pressure vs. Elevation

    NSDL National Science Digital Library

    In this data activity, students use NASA satellite measurements of atmospheric pressure to learn that pressure decreases with height in the atmosphere. Step-by-step instructions for use of the MY NASA DATA Live Access Server (LAS) guide students through selecting a data set, importing the data into a spreadsheet, creating graphs, and analyzing data plots. The lesson provides detailed procedures, related links and sample graphs, follow-up questions, extensions, and teacher notes. Designed for student use, MY NASA DATA LAS samples micro datasets from large scientific data archives, and provides structured investigations engaging students in exploration of remotely-sensed data to answer real world questions.

  6. Positive and negative gas-phase ion chemistry of chlorofluorocarbons in air at atmospheric pressure.

    PubMed

    Bosa, Elisabetta; Paradisi, Cristina; Scorrano, Gianfranco

    2003-01-01

    This paper presents a report on the ionization/dissociation of some representative chlorofluorocarbons (CFCs) induced by corona discharges in air at atmospheric pressure. Both positive and negative ions formed from Freons 1,1,1-trichlorotrifluoroethane (CFC 113a), 1,1,2-trichlorotrifluoroethane (CFC 113), and 1,1,1,2-tetrachlorodifluoroethane (CFC 112a) were analyzed using an atmospheric pressure chemical ionization mass spectrometry (APCI-MS) instrument. Energy-resolved mass spectra were obtained by modulating the kinetic energy of the ions via adjustment of the sampling cone potential (V(cone)). Positive ion spectra of the CFCs (M) at low V(cone) show no signals due to either M(+)* or MH(+) but only those due to species [M - Cl](+) and CX(3)(+) (X = Cl, F), likely formed via C-Cl and C-C bond cleavages following ionization via charge exchange. Charge localization in the products of C-C bond cleavage in M(+)* is driven by the stability of the neutral fragment. At low V(cone) the hydrates [M - Cl](+)(H(2)O) are also observed. In the case of 1,1,2,-trichlorotrifluoroethane, [M - F](+) species also form as a result of ion-molecule reactions. As V(cone) is increased collision-induced dissociation of [M - Cl](+) and [M - F](+), i.e., the perhalogenated cations C(2)X(5)(+) (X = Cl, F), takes place via carbene elimination. In some cases such elimination is preceded or accompanied by rearrangements involving transfer of halogen from one carbon to the other. Evidence is also presented for the occurrence of a condensation reaction of C(2)Cl(3)F(2)(+) with water to form a C(2)Cl(2)F(2)HO(+) species via elimination of HCl. Negative ion spectra are dominated by Cl(-) and its ion-neutral complexes with M and with water. Additional components of the plasma include ion-neutral complexes O(3)(-)(M), the molecular anion M(-) (observed only with 1,1,2-trichlorotrifluoroethane), and an interesting species corresponding to [M - Cl + O](-). The origin and structure of these [M - Cl + O](-) species are discussed in terms of available thermochemical and reactivity data and current mechanistic views concerning reaction of O(2)(-) with halogenated compounds. The observation of both positive and negative ions containing oxygen is of special relevance to development of new processes for the treatment of volatile organic compounds (VOCs) based on oxidative decomposition induced by corona discharges in air at room temperature and pressure. PMID:12478549

  7. Atmospheric pressure non-thermal plasma: Sources and applications

    NASA Astrophysics Data System (ADS)

    Napartovich, A. P.

    2008-07-01

    Non-thermal plasma at atmospheric pressure is an inherently unstable object. Nature of discharge plasma instabilities and conditions for observation of uniform non-thermal plasma at atmospheric pressure in different environments will be discussed. Various discharge techniques have been developed, which could support uniform non-thermal plasma with parameters varied in a wide range. Time limitation by plasma instabilities can be overcome by shortening pulse length or by restriction of plasma plug residence time with a fast gas flow. Discharge instabilities leading to formation of filaments or sparks are provoked by a positive feedback between the electric field and plasma density, while the counteracting process is plasma and thermal diffusion. With gas pressure growth the size of plasma fluctuation, which could be stabilized by diffusion, diminishes. As a result, to have long lived uniform plasma one should miniaturize discharge. There exist a number of active methods to organize negative feedback between the electric field and plasma density in order to suppress or, at least, delay the instability. Among them are ballast resistors in combination with electrode sectioning, reactive ballast, electronic feedback, and dielectric barrier across the electric current. The last methods are relevant for ac discharges. In the lecture an overview will be given of different discharge techniques scalable in pressure up to one atmosphere. The interest in this topic is dictated by a potential economic benefit from numerous non-thermal plasma technologies. The spectrum of non-thermal plasma applications is continuously broadening. An incomplete list of known applications includes: plasma-assisted chemical vapor deposition, etching, polymerization, gas-phase synthesis, protective coating deposition, toxic and harmful gas decomposition, destruction of warfare agents, electromagnetic wave shielding, polymer surface modifications, gas laser excitation, odor control, plasma assisted combustion, and gas dynamic flow control. Many of these applications have been developed with low-pressure plasma. Atmospheric pressure non-thermal plasma technologies possess such advantages as simplicity of operation and relatively low cost of equipments. A variety of available discharge techniques provides non-thermal plasma at atmospheric pressure in various gases with parameters covering a wide range in power densities, reduced electric field strengths and current densities. Requirements to non-thermal plasma parameters and sorts of gas for various applications vary widely, too. For any specific application the most appropriate discharge type can be found. The spectrum of discharge devices already existing is surprisingly broad. The problem of a successful choice of a discharge type for a specific application will be discussed. A particular emphasis will be placed on the problem of plasma removal of toxic and harmful species from the gas flow.

  8. Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji; Hori, Masaru

    2014-08-01

    Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

  9. Atmospheric Pressure Dielectric Barrier Discharges: A Low-Cost System for Surface Modification

    SciTech Connect

    Graz, I.; Schwoediauer, R.; Bauer, S. [Soft Matter Physics, Institute of Experimental Physics, Johannes Kepler University Linz (Austria); Gruber, H.; Romanin, C. [Institute for Biophysics, Johannes Kepler University Linz (Austria)

    2005-10-17

    Plasma treatment is a common way for modifying the surface of a material. A simple but effective source for a low-temperature nonequilibrium plasma is dielectric barrier discharges (DBDs), also referred to as silent discharges. DBDs are characterized by the presence of at least one insulating (dielectric) layer in the discharge gap between two metal electrodes. When a high voltage is applied to the DBD configuration, tiny breakdown channels are formed in the discharge gap. These microdischarges are characterized as a weakly ionized plasma containing electrons with energies up to 10 eV and ions at room temperature. The energetic electrons provide an effective tool for chemical surface modification. Typical setups for DBD treatments consist of vacuum chambers and vacuum equipment, and so are very cost-intensive. Atmospheric pressure discharges provide a possibility for low-cost surface chemistry, because the setup consists only of the discharge set-up in normal air or in a specified inert gas atmosphere and a high-voltage amplifier coupled with a frequency generator. Silent discharges in air increase the wettability of polymer foils such as PTFE and FEP, sufficient for cell growth and further for surface-chemical binding of proteins onto the polymer. Thereby a simple and low-cost process to achieve protein chips for biomedical applications may be envisaged.

  10. Nonlinear frequency coupling in dual radio-frequency driven atmospheric pressure plasmas

    SciTech Connect

    Waskoenig, J.; Gans, T. [Centre for Plasma Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2010-05-03

    Plasma ionization, and associated mode transitions, in dual radio-frequency driven atmospheric pressure plasmas are governed through nonlinear frequency coupling in the dynamics of the plasma boundary sheath. Ionization in low-power mode is determined by the nonlinear coupling of electron heating and the momentary local plasma density. Ionization in high-power mode is driven by electron avalanches during phases of transient high electric fields within the boundary sheath. The transition between these distinctly different modes is controlled by the total voltage of both frequency components.

  11. Atmospheric pressure photoionization mass spectrometry as a tool for the investigation of the hydrolysis reaction mechanisms of phosphite antioxidants

    NASA Astrophysics Data System (ADS)

    Papanastasiou, M.; McMahon, A. W.; Allen, N. S.; Johnson, B. W.; Keck-Antoine, K.; Santos, L.; Neumann, M. G.

    2008-08-01

    The hydrolysis reaction mechanism of phosphite antioxidants is investigated by liquid chromatography-mass spectrometry (LC/MS). The phosphites were chosen because they differed in chemical structure and phosphorus content. Dopant assisted-atmospheric pressure photoionization (DA-APPI) is chosen as the ion source for the ionization of the compounds. In our previous work, DA-APPI was shown to offer an attractive alternative to atmospheric pressure chemical ionization (APCI) since it provided background-ion free mass spectra and higher sensitivity [M. Papanastasiou, et al., Polymer Degradation and Stability 91 (11) (2006) 2675-2682]. In positive ion mode, the molecules are generally detected in their protonated form. In negative ion mode, the phosphites are unstable and only fragment ions are observed; these however, are characteristic of each phosphite and may be used for the identification of the analytes in complex mixtures. The analytes under investigation are exposed to accelerated humid ageing conditions and their hydrolytic pathway and stability is investigated. Different substituents around the phosphorus atom are shown to have a significant effect on the stability of the phosphites, with phenol substituents producing very hydrolytically stable structures. Alkanox P24 and PEP-36 follow a similar hydrolytic pathway via the scission of the first and then the second POphenol bonds, eventually leading to the formation of phenol, phosphorous acid and pentaerythritol as end products. HP-10 exhibits a rather different structure and the products detected suggest scission of either the POhydrocarbon or one of the POphenol bonds. A phenomenon similar to that of autocatalysis is observed for all phosphites and is attributed to the formation of dialkyl phosphites as intermediate products.

  12. Self-consistent chemical model of partially ionized plasmas.

    PubMed

    Arkhipov, Yu V; Baimbetov, F B; Davletov, A E

    2011-01-01

    A simple renormalization theory of plasma particle interactions is proposed. It primarily stems from generic properties of equilibrium distribution functions and allows one to obtain the so-called generalized Poisson-Boltzmann equation for an effective interaction potential of two chosen particles in the presence of a third one. The same equation is then strictly derived from the Bogolyubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy for equilibrium distribution functions in the pair correlation approximation. This enables one to construct a self-consistent chemical model of partially ionized plasmas, correctly accounting for the close interrelation of charged and neutral components thereof. Minimization of the system free energy provides ionization equilibrium and, thus, permits one to study the plasma composition in a wide range of its parameters. Unlike standard chemical models, the proposed one allows one to study the system correlation functions and thereby to obtain an equation of state which agrees well with exact results of quantum-mechanical activity expansions. It is shown that the plasma and neutral components are strongly interrelated, which results in the short-range order formation in the corresponding subsystem. The mathematical form of the results obtained enables one to both firmly establish this fact and to determine a characteristic length of the structure formation. Since the cornerstone of the proposed self-consistent chemical model of partially ionized plasmas is an effective pairwise interaction potential, it immediately provides quite an efficient calculation scheme not only for thermodynamical functions but for transport coefficients as well. PMID:21405782

  13. Propagation of an atmospheric pressure plasma plume

    SciTech Connect

    Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2009-02-15

    The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

  14. Propagation of an atmospheric pressure plasma plume

    NASA Astrophysics Data System (ADS)

    Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

    2009-02-01

    The "plasma bullet" behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

  15. The evolution of atmospheric-pressure low-temperature plasma jets: jet current measurements

    Microsoft Academic Search

    Erdinc Karakas; Mehmet Arda Akman; Mounir Laroussi

    2012-01-01

    In this study, we report insights into the dynamics of atmospheric-pressure low-temperature plasma jets (APLTPJs). The plasma jet current was measured by a Pearson current monitor for different operating conditions. These jet current measurements confirmed a proposed photo-ionization model based on streamer theory. Our results are supported by intensified charged-couple device camera observations. It was found that a secondary discharge

  16. Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma

    Microsoft Academic Search

    Paola Brun; Maria Vono; Paola Venier; Elena Tarricone; Velika Deligianni; Emilio Martines; Matteo Zuin; Silvia Spagnolo; Roberto Cavazzana; Romilda Cardin; Ignazio Castagliuolo; Alvise La Gloria Valerio; Andrea Leonardi

    2012-01-01

    BackgroundLow temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage.Methodology\\/Principal FindingsWe tested the

  17. Microwave-excited atmospheric pressure plasma jet with wide aperture for the synthesis of carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Kim, Jaeho; Sakakita, Hajime; Ohsaki, Hiroyuki; Katsurai, Makoto

    2015-01-01

    Atmospheric pressure chemical vapor deposition (APCVD) has preferable properties to the mass production of carbon nanomaterials. Here, we describe a specially-designed microwave-excited atmospheric pressure plasma jet (MW-APPJ) with a 10-mm-wide nozzle based on microstrip line. The MW-APPJ is applied to an APCVD process and nanocrystalline diamond films are successfully deposited on silicon substrates using a mixture gas of Ar/CH4/H2 even in ambient air. The MW-APPJ technology could be suitable for the large-area APCVD system for the synthesis of carbon nanomaterials due to its arrayed configuration for the enlargement of plasma area.

  18. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1?g), and 2.9 x 10^12 cm-3 O2(^1?^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1?g) metastables were responsible for killing the anthrax and other microorganisms.

  19. Atmospheric pressure discharge plasma decomposition for gaseous air contaminants-trichlorotrifluoroethane and trichloroethylene

    Microsoft Academic Search

    Tetsuji Oda; Ryuichi Yamashita; Tadashi Takahashi; Senichi Masuda

    1996-01-01

    The decomposition performance of gaseous environmental destructive contaminants in air by using atmospheric pressure discharge plasma including the surface discharge induced plasma chemical processing (SPCP) was examined. The main contaminants tested were chlorofluorocarbon (CFC-113) and trichloroethylene, typically. The discharge exciting frequency range studied was wide-50 Hz to 50 kHz. Results showed the low frequency discharge requires high voltage to inject

  20. Development and spectroscopic investigation of a microwave plasma source at atmospheric pressure

    Microsoft Academic Search

    M. Leins; A. Schulz; M. Walker; U. Schumacher; U. Stroth

    2010-01-01

    Summary form only given.Microwave plasma sources at atmospheric pressure have a variety of different applications. On the one hand they can be used for the treatment of surfaces, for example the activation or cleaning, and on the other hand they can be applied for the conversion of gases, such as the abatement of waste gases or other chemical synthesis. The

  1. On the growth mode of two-lobed curvilinear graphene domains at atmospheric pressure

    PubMed Central

    Kumar, Kitu; Yang, Eui-Hyeok

    2013-01-01

    We demonstrate the chemical vapor deposition (CVD) growth of 2-lobed symmetrical curvilinear graphene domains specifically on Cu{100} surface orientations at atmospheric pressure. We utilize electron backscattered diffraction, scanning electron microscopy and Raman spectroscopy to determine an as-yet unexplored growth mode producing such a shape and demonstrate how its growth and morphology are dependent on the underlying Cu crystal structure especially in the high CH4:H2 regime. We show that both monolayer and bilayer curvilinear domains are grown on Cu{100} surfaces; furthermore, we show that characteristic atmospheric pressure CVD hexagonal domains are grown on all other Cu facets with an isotropic growth rate which is more rapid than that on Cu{100}. These findings indicate that the Cu-graphene complex is predominant mechanistically at atmospheric pressure, which is an important step towards tailoring graphene properties via substrate engineering. PMID:23999168

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

    PubMed Central

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

    2008-01-01

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

  3. Response of cyanobacteria to low atmosphere pressure

    NASA Astrophysics Data System (ADS)

    Qin, Lifeng; Ai, Weidang; Guo, Shuangsheng; Tang, Yongkang; Yu, Qingni; Shen, Yunze; Ren, Jin

    Maintaining a low pressure environment would reduce the technological complexity and constructed cost of future lunar base. To estimate the effect of hypobaric of controlled ecological life support system in lunar base on terrestrial life, cyanobacteria was used as the model to exam the response of growth, morphology, physiology to it. The decrease of atmosphere pressure from 100 KPa to 50 KPa reducing the growth rates of Microcystis aeruginosa, Merismopedia.sp, Anabaena sp. PCC 7120, Anabaena Hos-aquae, the chlorophyll a content in Microcystis aeruginosa, Merismopedia.sp, Anabaena Hos-aquae, the carotenoid content in Microcystis aeruginosa, Merismopedia.sp and Anabaena sp. PCC 7120, the phycocyanin content in Microcystis aeruginosa. This study explored the biological characteristics of the cyanobacteria under low pressure condition, which aimed at understanding the response of the earth's life to environment for the future moon base, the results enrich the research contents of the lunar biology and may be referred for the research of other terrestrial life, such as human, plant, microbe and animal living in life support system of lunar base.

  4. Chaos in atmospheric-pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Iza, F.; Janson, N. B.; Kong, M. G.

    2012-06-01

    We report detailed characterization of a low-temperature atmospheric-pressure plasma jet that exhibits regimes of periodic, quasi-periodic and chaotic behaviors. Power spectra, phase portraits, stroboscopic section and bifurcation diagram of the discharge current combine to comprehensively demonstrate the existence of chaos, and this evidence is strengthened with a nonlinear dynamics analysis using two control parameters that maps out periodic, period-multiplication, and chaotic regimes over a wide range of the input voltage and gas flow rate. In addition, optical emission signatures of excited plasma species are used as the second and independent observable to demonstrate the presence of chaos and period-doubling in both the concentrations and composition of plasma species, suggesting a similar array of periodic, quasi-periodic and chaotic regimes in plasma chemistry. The presence of quasi-periodic and chaotic regimes in structurally unbounded low-temperature atmospheric plasmas not only is important as a fundamental scientific topic but also has interesting implications for their numerous applications. Chaos may be undesirable for industrial applications where cycle-to-cycle reproducibility is important, yet for treatment of cell-containing materials including living tissues it may offer a novel route to combat some of the major challenges in medicine such as drug resistance. Chaos in low-temperature atmospheric plasmas and its effective control are likely to open up new vistas for medical technologies.

  5. The Chemical and Ionization Conditions in Weak Mg II Absorbers

    E-print Network

    Anand Narayanan; Jane C. Charlton; Toru Misawa; Rebecca E. Green; Tae-Sun Kim

    2008-08-19

    We present an analysis of the chemical and ionization conditions in a sample of 100 weak Mg II absorbers identified in the VLT/UVES archive of quasar spectra. Using a host of low ionization lines associated with each absorber in this sample, and on the basis of ionization models, we infer that the metallicity in a significant fraction of weak Mg II clouds is constrained to values of solar or higher, if they are sub-Lyman limit systems. Based on the observed constraints, we present a physical picture in which weak Mg II absorbers are predominantly tracing two different astrophysical processes/structures. A significant population of weak Mg II clouds, those in which N(Fe II) is much less than N(Mg II), identified at both low (z ~ 1) and high (z ~ 2) redshift, are potentially tracing gas in the extended halos of galaxies, analogous to the Galactic high velocity clouds. These absorbers might correspond to alpha-enhanced interstellar gas expelled from star-forming galaxies, in correlated supernova events. On the other hand, N(FeII) approximately equal to N(Mg II) clouds, which are prevalent only at lower redshifts (z < 1.5), must be tracing Type Ia enriched gas in small, high metallicity pockets in dwarf galaxies, tidal debris, or other intergalactic structures.

  6. Radiative ion-ion neutralization: a new gas-phase atmospheric pressure ion transduction mechanism.

    PubMed

    Davis, Eric J; Siems, William F; Hill, Herbert H

    2012-06-01

    All atmospheric pressure ion detectors, including photo ionization detectors, flame ionization detectors, electron capture detectors, and ion mobility spectrometers, utilize Faraday plate designs in which ionic charge is collected and amplified. The sensitivity of these Faraday plate ion detectors are limited by thermal (Johnson) noise in the associated electronics. Thus approximately 10(6) ions per second are required for a minimal detection. This is not the case for ion detection under vacuum conditions where secondary electron multipliers (SEMs) can be used. SEMs produce a cascade of approximately 10(6) electrons per ion impinging on the conversion dynode. Similarly, photomultiplier tubes (PMTs) can generate approximately 10(6) electrons per photon. Unlike SEMs, however, PMTs are evacuated and sealed so that they are commonly used under atmospheric pressure conditions. This paper describes an atmospheric pressure ion detector based on coupling a PMT with light emitted from ion-ion neutralization reactions. The normal Faraday plate collector electrode was replaced with an electrode "needle" used to concentrate the anions as they were drawn to the tip of the needle by a strong focusing electric field. Light was emitted near the surface of the electrode when analyte ions were neutralized with cations produced from the anode. Although radiative-ion-ion recombination has been previously reported, this is the first time ions from separate ionization sources have been combined to produce light. The light from this radiative-ion-ion-neutralization (RIIN) was detected using a photon multiplier such that an ion mobility spectrum was obtained by monitoring the light emitted from mobility separated ions. An IMS spectrum of nitroglycerin (NG) was obtained utilizing RIIN for tranducing the mobility separated ions into an analytical signal. The implications of this novel ion transduction method are the potential for counting ions at atmospheric pressure and for obtaining ion specific emission spectra for mobility separated ions. PMID:22548633

  7. Atmospheric pressure loading effects on Global Positioning System coordinate determinations

    Microsoft Academic Search

    Tonie M. vanDam; Geoffrey Blewitt; Michael B. Heflin

    1994-01-01

    Earth deformation signals caused by atmospheric pressure loading are detected in vertical position estimates at Global Positioning System (GPS) stations. Surface displacements due to changes in atmospheric pressure account for up to 24% of the total variance in the GPS height estimates. The detected loading signals are larger at higher latitudes where pressure variations are greatest; the largest effect is

  8. A RF Discharge in Argon at Atmospheric Pressure

    Microsoft Academic Search

    Shirshak Dhali; Navin Muthuswamy; Bakul Dave

    2001-01-01

    A dual chamber dischrage is used to create an atmospheric pressure plasma in Argon. The discharge consists of two chambers: one at low pressure (few Torrs) and the other at atmospheric pressure. The chambers are seperated by fused silica window. A RF source(13.56 MHz) is used to create a discharge first in the low pressure chamber which is filled with

  9. Analytical model of atmospheric pressure, helium/trace gas radio-frequency capacitive Penning discharges

    NASA Astrophysics Data System (ADS)

    Lieberman, M. A.

    2015-04-01

    Atmospheric and near-atmospheric pressure, helium/trace gas radio-frequency capacitive discharges have wide applications. An analytic equilibrium solution is developed based on a homogeneous, current-driven discharge model that includes sheath and electron multiplication effects and contains two electron populations. A simplified chemistry is used with four unknown densities: hot electrons, warm electrons, positive ions and metastables. The dominant electron–ion pair production is Penning ionization, and the dominant ion losses are to the walls. The equilibrium particle balances are used to determine a single ionization balance equation for the warm electron temperature, which is solved, both approximately within the ?- and ?-modes, and exactly by conventional root-finding techniques. All other discharge parameters are found, the extinction and ?-? transitions are determined, and a similarity law is given, in which the equilibrium for a short gap at high pressure can be rescaled to a longer gap at lower pressure. Within the ?-mode, we find the scaling of the discharge parameters with current density, frequency, gas density and gap width. The analytic results are compared to hybrid and particle-in-cell (PIC) results for He/0.1%N2, and to hybrid results for He/0.1%H2O. For nitrogen, a full reaction set is used for the hybrid calculations and a simplified reaction set for the PIC simulations. For the chemically complex water trace gas, a set of 209 reactions among 43 species is used. The analytic results are found to be in reasonably good agreement with the more elaborate hybrid and PIC calculations.

  10. Formation of plasma dust structures at atmospheric pressure

    SciTech Connect

    Filippov, A. V., E-mail: fav@triniti.ru; Babichev, V. N.; Dyatko, N. A.; Pal', A. F.; Starostin, A. N.; Taran, M. D. [Troitsk Institute for Innovation and Fusion Research, State Research Center of Russian Federation (Russian Federation); Fortov, V. E. [Russian Academy of Sciences, Institute for High Energy Densities (Russian Federation)

    2006-02-15

    The formation of strongly coupled stable dust structures in the plasma produced by an electron beam at atmospheric pressure was detected experimentally. Analytical expressions were derived for the ionization rate of a gas by an electron beam in an axially symmetric geometry by comparing experimental data with Monte Carlo calculations. Self-consistent one-dimensional simulations of the beam plasma were performed in the diffusion drift approximation of charged plasma particle transport with electron diffusion to determine the dust particle levitation conditions. Since almost all of the applied voltage drops on the cathode layer in the Thomson glow regime of a non-self-sustained gas discharge, a distribution of the electric field that grows toward the cathode is produced in it; this field together with the gravity produces a potential well in which the dust particles levitate to form a stable disk-shaped structure. The nonideality parameters of the dust component in the formation region of a highly ordered quasi-crystalline structure calculated using computational data for the dust particle charging problem were found to be higher than the critical value after exceeding which an ensemble of particles with a Yukawa interaction should pass to the crystalline state.

  11. Atmospheric pressure molecular imaging by infrared MALDI mass spectrometry.

    PubMed

    Li, Yue; Shrestha, Bindesh; Vertes, Akos

    2007-01-15

    An atmospheric pressure (AP) MALDI imaging interface was developed for an orthogonal acceleration time-of-flight mass spectrometer and utilized to analyze peptides, carbohydrates, and other small biomolecules using infrared laser excitation. In molecular imaging experiments, the spatial distribution of mock peptide patterns was recovered with a detection limit of approximately 1 fmol/pixel from a variety of MALDI matrixes. With the use of oversampling for the image acquisition, a spatial resolution of 40 microm, 5 times smaller than the laser spot size, was achieved. This approach, however, required that the analyte was largely removed at the point of analysis before the next point was interrogated. Native water in plant tissue was demonstrated to be an efficient natural matrix for AP infrared laser desorption ionization. In soft fruit tissues from bananas, grapes, and strawberries, potassiated ions of the most abundant metabolites, small carbohydrates, and their clusters produced the strongest peaks in the spectra. Molecular imaging of a strawberry skin sample revealed the distribution of the sucrose, glucose/fructose, and citric acid species around the embedded seeds. Infrared AP MALDI mass spectrometric imaging without the addition of an artificial matrix enables the in vivo investigation of small biomolecules and biological processes (e.g., metabolomics) in their natural environment. PMID:17222016

  12. Methods for estimating the bioconcentration factor of ionizable organic chemicals.

    PubMed

    Fu, Wenjing; Franco, Antonio; Trapp, Stefan

    2009-07-01

    The bioaccumulation potential is an important criterion in risk assessment of chemicals. Several regressions between bioconcentration factor (BCF) in fish and octanol-water partition coefficient (K(OW)) have been developed for neutral organic compounds, but very few approaches address the BCF of ionizable compounds. A database with BCFs of 73 acids and 65 bases was collected from the literature. The BCF estimation method recommended by the Technical Guidance Document (TGD) for chemical risk assessment in the European Union was tested for ionizing substances using log K(OW) (corrected for the neutral species, log[ f(n) x K(OW)]) and log D (sum of log K(OW) of neutral and ionic molecule, apparent log K(OW)) as predictors. In addition, the method of Meylan et al. (Environ Toxicol Chem 1999; 18:664-672) for ionizable compounds and a dynamic cell model based on the Fick- Nernst-Planck equation were tested. Moreover, our own regressions for the BCF were established from log K(OW) and pK(a). The bioaccumulation of lipophilic compounds depends mainly on their lipophilicity, and the best predictor is log D. Dissociation, the pH-dependent ion trap, and electrical attraction of cations impact the BCF. Several methods showed acceptable results. The TGD regressions gave good predictions when log( f(n) x K(OW)) or log D were used as a predictor instead of log K(OW). The new regressions to log K(OW) and pK(a) performed similarly, with mean errors of approximately 0.4. The method of Meylan et al. did not perform as well. The cell model showed weak results for acids but was among the best methods for bases. PMID:19245273

  13. Cold plasma brush generated at atmospheric pressure

    SciTech Connect

    Duan Yixiang; Huang, C.; Yu, Q. S. [C-CSE, MS K484, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Chemical Engineering, Center for Surface Science and Plasma Technology, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

    2007-01-15

    A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 deg. C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds.

  14. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer

    NASA Astrophysics Data System (ADS)

    Babij, Micha?; Kowalski, Zbigniew W.; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet.

  15. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer.

    PubMed

    Babij, Micha?; Kowalski, Zbigniew W; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet. PMID:24880391

  16. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer

    SciTech Connect

    Babij, Micha?; Kowalski, Zbigniew W., E-mail: zbigniew.w.kowalski@pwr.wroc.pl; Nitsch, Karol; Gotszalk, Teodor [Wroc?aw University of Technology, Wybrze?e Wyspia?skiego 27, 50-370 Wroc?aw (Poland)] [Wroc?aw University of Technology, Wybrze?e Wyspia?skiego 27, 50-370 Wroc?aw (Poland); Silberring, Jerzy [AGH University of Science and Technology, Al. A. Mickiewicza 30, 30-059 Kraków (Poland)] [AGH University of Science and Technology, Al. A. Mickiewicza 30, 30-059 Kraków (Poland)

    2014-05-15

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet.

  17. Comparison of direct and alternating current vacuum ultraviolet lamps in atmospheric pressure photoionization.

    PubMed

    Vaikkinen, Anu; Haapala, Markus; Kersten, Hendrik; Benter, Thorsten; Kostiainen, Risto; Kauppila, Tiina J

    2012-02-01

    A direct current induced vacuum ultraviolet (dc-VUV) krypton discharge lamp and an alternating current, radio frequency (rf) induced VUV lamp that are essentially similar to lamps in commercial atmospheric pressure photoionization (APPI) ion sources were compared. The emission distributions along the diameter of the lamp exit window were measured, and they showed that the beam of the rf lamp is much wider than that of the dc lamp. Thus, the rf lamp has larger efficient ionization area, and it also emits more photons than the dc lamp. The ionization efficiencies of the lamps were compared using identical spray geometries with both lamps in microchip APPI mass spectrometry (?APPI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). A comprehensive view on the ionization was gained by studying six different ?APPI solvent compositions, five DAPPI spray solvents, and completely solvent-free DAPPI. The observed reactant ions for each solvent composition were very similar with both lamps except for toluene, which showed a higher amount of solvent originating oxidation products with the rf lamp than with the dc lamp in ?APPI. Moreover, the same analyte ions were detected with both lamps, and thus, the ionization mechanisms with both lamps are similar. The rf lamp showed a higher ionization efficiency than the dc lamp in all experiments. The difference between the lamp ionization efficiencies was greatest when high ionization energy (IE) solvent compositions (IEs above 10 eV), i.e., hexane, methanol, and methanol/water, (1:1 v:v) were used. The higher ionization efficiency of the rf lamp is likely due to the larger area of high intensity light emission, and the resulting larger efficient ionization area and higher amount of photons emitted. These result in higher solvent reactant ion production, which in turn enables more efficient analyte ion production. PMID:22229729

  18. Atmospheric Pressure Plasmas for Decontamination of Complex Medical Devices

    NASA Astrophysics Data System (ADS)

    Weltmann, Klaus-Dieter; Winter, Jörn; Polak, Martin; Ehlbeck, Jörg; von Woedtke, Thomas

    Atmospheric pressure plasma sources produce a multiplicity of different antimicrobial agents and are applicable to even complicated geometries as well as to heat sensitive materials. Thus, atmospheric pressure plasmas have a huge potential for the decontamination of even complex medical devices like central venous catheters and endoscopes. In this paper we present practicable realizations of atmospheric pressure plasma sources, namely plasma jet, dielectric barrier discharge and microwave driven discharge that are able to penetrate fine lumen or are adaptable to difficult geometries. Furthermore, the antimicrobial efficacy of these sources is given for one example setup in each case.

  19. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

  20. Identification of volatile and semivolatile compounds in chemical ionization GC-MS using a mass-to-structure (MTS) Search Engine with integral isotope pattern ranking.

    PubMed

    Liao, Wenta; Draper, William M

    2013-02-21

    The mass-to-structure or MTS Search Engine is an Access 2010 database containing theoretical molecular mass information for 19,438 compounds assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. This database, which contains no experimental mass spectral data, was developed as an aid to identification of compounds in atmospheric pressure ionization (API)-LC-MS. This paper describes a powerful upgrade to this database, a fully integrated utility for filtering or ranking candidates based on isotope ratios and patterns. The new MTS Search Engine is applied here to the identification of volatile and semivolatile compounds including pesticides, nitrosoamines and other pollutants. Methane and isobutane chemical ionization (CI) GC-MS spectra were obtained from unit mass resolution mass spectrometers to determine MH(+) masses and isotope ratios. Isotopes were measured accurately with errors of <4% and <6%, respectively, for A + 1 and A + 2 peaks. Deconvolution of interfering isotope clusters (e.g., M(+) and [M - H](+)) was required for accurate determination of the A + 1 isotope in halogenated compounds. Integrating the isotope data greatly improved the speed and accuracy of the database identifications. The database accurately identified unknowns from isobutane CI spectra in 100% of cases where as many as 40 candidates satisfied the mass tolerance. The paper describes the development and basic operation of the new MTS Search Engine and details performance testing with over 50 model compounds. PMID:23248816

  1. Visualization of a Copper Wire Explosion in Atmospheric Pressure Air

    E-print Network

    Jadidian, Jouya

    Experimental and computational images of a 90-?m thick copper wire explosion in atmospheric pressure air are presented. A Marx generator is used to produce a pulsed current density into the wire with a maximum rate of rise ...

  2. Investigating Atmospheric Pressure with a Cup, Straw and Water

    NSDL National Science Digital Library

    This activity is a reinforcement lab activity where students experiment with ways to get water to flow out of a cup and up a straw causing an imbalance in the atmospheric pressure surrounding the water.

  3. Hydrogenation of unsaturated fatty esters during isobutane chemical ionization mass spectrometry

    Microsoft Academic Search

    William K. Rohwedder; Sandra M. Cox

    1984-01-01

    Hydrogenation of double bonds was observed to occur during the isobutane chemical ionization mass spectrometry (MS) of unsaturated\\u000a fatty esters. Chemical ionization (CI) spectra of a series of methyl esters in the C16–C20 carbon range containing 0–4 double\\u000a bonds showed a variety of ionization characteristics in the molecular ion cluster, including hydride abstraction, charge exchange,\\u000a protonation and, for the unsaturated

  4. Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids.

    E-print Network

    Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids. II 7 June 2001 Chemical ionization tandem mass spectrometry (CI-MS/MS) of alkaloids with ammonia alkaloids in extracts from six pseudomyrmecine ants of the genus Tetraponera. The MS/MS techniques along

  5. Peroxy radical observations using chemical ionization mass spectrometry during TOPSE

    NASA Astrophysics Data System (ADS)

    Cantrell, Christopher A.; Edwards, G. D.; Stephens, S.; Mauldin, L.; Kosciuch, E.; Zondlo, M.; Eisele, F.

    2003-03-01

    Peroxy radicals (HO2 + RO2) were measured by chemical conversion-chemical ionization mass spectroscopy in the TOPSE (Tropospheric Ozone Production about the Spring Equinox) campaign that took place February through May 2000. Instrumentation for these measurements was deployed on the NCAR/NSF C-130 aircraft that flew at latitudes from 40 to 85°N, and altitudes from the surface to 7.5 km over the North American continent. The measurements demonstrate the evolution of photochemical activity as time progresses through the study period due to increases in free radical source rates. The increase in average peroxy radical concentration moves northward as the maximum solar elevation and length of sunlit days increase. HOxROx (HO2 + RO2) concentrations are distributed lognormally with means of 11.5 and 7.8 pptv for the middle-latitude band (MLB) and high-latitude band (HLB), respectively. The observations agree well on average with steady state derived concentrations; measurement-model concentration ratios are 1.04 (MLB) and 0.94 (HLB). Concentrations within a given latitude band and altitude region sometimes appear to increase with NOx concentrations, but this correlation nearly disappears at low and moderate NOx levels when the data are parsed by radical production rate; lower radical levels are observed at the highest NOx levels measured (near 1 ppbv). These data are compared with results from other recent observations utilizing a variety of platforms.

  6. Martian Atmospheric Pressure Static Charge Elimination Tool

    NASA Technical Reports Server (NTRS)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  7. Atmospheric pressure plasma treatment of lipopolysaccharide in a controlled environment

    NASA Astrophysics Data System (ADS)

    Bartis, E. A. J.; Graves, D. B.; Seog, J.; Oehrlein, G. S.

    2013-08-01

    The atmospheric pressure plasma jet (APPJ) has been widely investigated for sterilization of surfaces, but studies on surface chemical changes of model compounds in controlled environments have been lacking. We present measurements on lipopolysaccharide (LPS) using x-ray photoelectron spectroscopy after 1% O2 in Ar APPJ treatments in controlled ambients composed of N2/Ar mixtures. By varying the N2 concentration from 20% to 100%, we find that the interaction of the jet with the environment plays a major role in modifying surface reactions. This is due to the plasma exciting N2, which quenches reactive oxygen species (ROS) that would otherwise modify the film surface. By minimizing the interaction of the APPJ with the environment, e.g. by changing the APPJ geometry, we show that surface modifications increase even when the plasma itself is removed farther from the LPS surface. Measurements on the biological activity, optical emission, and ozone production of the jet using O2, N2 and O2/N2 admixtures all demonstrate that ROS are readily quenched by N2 species excited by the plasma. These results clearly reveal the importance of considering plasma-environment interactions for APPJ treatments of surfaces.

  8. EDITORIAL: Atmospheric pressure non-thermal plasmas for processing and other applications

    NASA Astrophysics Data System (ADS)

    Massines, Françoise

    2005-02-01

    Interest has grown over the past few years in applying atmospheric pressure plasmas to plasma processing for the benefits this can offer to existing and potential new processes, because they do not require expensive vacuum systems and batch processing. There have been considerable efforts to efficiently generate large volumes of homogeneous atmospheric pressure non-thermal plasmas to develop environmentally friendly alternatives for surface treatment, thin film coating, sterilization, decontamination, etc. Many interesting questions have arisen that are related to both fundamental and applied research in this field. Many concern the generation of a large volume discharge which remains stable and uniform at atmospheric pressure. At this pressure, depending on the experimental conditions, either streamer or Townsend breakdown may occur. They respectively lead to micro-discharges or to one large radius discharge, Townsend or glow. However, the complexity arises from the formation of large radius streamers due to avalanche coupling and from the constriction of the glow discharge due to too low a current. Another difficulty is to visually distinguish many micro-discharges from one large radius discharge. Other questions relate to key chemical reactions in the plasma and at the surface. Experimental characterization and modelling also need to be developed to answer these questions. This cluster collects up-to-date research results related to the understanding of different discharges working at atmospheric pressure and the application to polymer surface activation and thin film coating. It presents different solutions for generating and sustaining diffuse discharges at atmospheric pressure. DC, low-frequency and radio-frequency excitations are considered in noble gases, nitrogen or air. Two specific methods developed to understand the transition from Townsend to streamer breakdown are also presented. They are based on the cross-correlation spectroscopy and an electrical model.

  9. Polyethyleneterephthalate surface modification mechanisms by an atmospheric pressure RF plasma source

    NASA Astrophysics Data System (ADS)

    Yang, Shujun; Tang, Jiansheng

    2012-10-01

    An atmospheric pressure plasma was generated by a RF capacitive discharge using Helium gas or a mixture of helium and oxygen. The plasma was used to modify polyethyleneterephthalate (PET) surfaces with extremely high throughput. The surface modification mechanisms were carefully investigated. The modification was determined to be mainly a chemical and photochemical process through the experiments and analysis on ions, UV light, oxygen atoms, and ozone molecules.

  10. CO^+ and C_2 Spectra Generated by CO_2 Atmospheric Pressure Glow Discharges in Microchannels

    NASA Astrophysics Data System (ADS)

    Shin, Chul; Dai, Zhen; Houlahan, Thomas J., Jr.; Park, Sung-Jin; Eden, Gary

    2014-06-01

    Intense emission in the near-ultraviolet and visible from the Comet Tail and Swan bands of CO^+ and C_2, respectively, has been observed from glow discharges produced in CO_2 at atmospheric pressure. Generated within 200--500 ?m microchannels fabricated in nanoporous alumina, the microchannel plasmas are spatially homogeneous, diffuse glows. As the CO_2 flow rate through the microchannels is varied, the visible/UV spectra change dramatically and the chemical kinetics of this fascinating spectrum will be discussed.

  11. Analysis of Ternary InGaN Layers Grown By Atmospheric Pressure Vertical MOVPE

    SciTech Connect

    Yildiz, A.; Ozturk, M. K.; Kasap, M. [Department of Physics, Gazi University, Ankara (Turkey)

    2007-04-23

    We present a study on the n-type ternary InGaN layers grown by atmospheric pressure vertical metal organic chemical vapor deposition on GaN template/(0001) sapphire substrate. An investigation in the different growth conditions on n-type of the InxGa1-xN, alloys was made for three series samples. Structural, electrical and optical properties were characterized by High X-Ray Diffraction, Hall effect and Photoluminescence respectively.

  12. Dynamics and particle fluxes in atmospheric-pressure electronegative radio frequency microplasmas

    SciTech Connect

    McKay, K.; Iza, F.; Kong, M. G. [School of Electronic, Electrical and Systems Engineering, Loughborough University, Loughborough, LE11-3TU (United Kingdom); Liu, D. X.; Rong, M. Z. [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049 (China)

    2011-08-29

    We report on intricate dynamics observed in atmospheric-pressure rf electronegative discharges where electrons and anions are separated due to their different mobilities. This results in the formation of positively charged regions between an electronegative plasma core and an oscillating electron ensemble. It is found that for a given input power, the electron, ion (both positive and negative) and neutral fluxes increase as the gap size is reduced, resulting in a more efficient delivery of chemical species to a treated target.

  13. Surface modification of acrylate intraocular lenses with dielectric barrier discharge plasma at atmospheric pressure

    Microsoft Academic Search

    Yao Wang; ZhenMei Liu; ZhiKang Xu; Ke Yao

    2009-01-01

    Surface modification with dielectric barrier discharge (DBD) plasma was carried out at atmospheric pressure (argon as the\\u000a discharge gas) to improve the biocompatibility of hydrophobic acrylate intraocular lens (IOL). Changes of the plasma-treated\\u000a IOL surface in chemical composition, morphology and hydrophilicity were comprehensively evaluated by X-ray photoelectron spectroscopy\\u000a (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and

  14. Processing materials inside an atmospheric-pressure radiofrequency nonthermal plasma discharge

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Park, Jaeyoung; Herrmann, Hans W.

    2006-04-11

    Apparatus for the processing of materials involving placing a material either placed between an radio-frequency electrode and a ground electrode, or which is itself one of the electrodes. This is done in atmospheric pressure conditions. The apparatus effectively etches or cleans substrates, such as silicon wafers, or provides cleaning of spools and drums, and uses a gas containing an inert gas and a chemically reactive gas.

  15. Non-Thermal Atmospheric-Pressure Plasma Possible Application in Wound Healing

    PubMed Central

    Haertel, Beate; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Lindequist, Ulrike

    2014-01-01

    Non-thermal atmospheric-pressure plasma, also named cold plasma, is defined as a partly ionized gas. Therefore, it cannot be equated with plasma from blood; it is not biological in nature. Non-thermal atmospheric-pressure plasma is a new innovative approach in medicine not only for the treatment of wounds, but with a wide-range of other applications, as e.g. topical treatment of other skin diseases with microbial involvement or treatment of cancer diseases. This review emphasizes plasma effects on wound healing. Non-thermal atmospheric-pressure plasma can support wound healing by its antiseptic effects, by stimulation of proliferation and migration of wound relating skin cells, by activation or inhibition of integrin receptors on the cell surface or by its pro-angiogenic effect. We summarize the effects of plasma on eukaryotic cells, especially on keratinocytes in terms of viability, proliferation, DNA, adhesion molecules and angiogenesis together with the role of reactive oxygen species and other components of plasma. The outcome of first clinical trials regarding wound healing is pointed out. PMID:25489414

  16. Investigation of ion-ion-recombination at atmospheric pressure with a pulsed electron gun.

    PubMed

    Heptner, Andre; Cochems, Philipp; Langejuergen, Jens; Gunzer, Frank; Zimmermann, Stefan

    2012-11-01

    For future development of simple miniaturized sensors based on pulsed atmospheric pressure ionization as known from ion mobility spectrometry, we investigated the reaction kinetics of ion-ion-recombination to establish selective ion suppression as an easy to apply separation technique for otherwise non-selective ion detectors. Therefore, the recombination rates of different positive ion species, such as protonated water clusters H(+)(H(2)O)(n) (positive reactant ions), acetone, ammonia and dimethyl-methylphosphonate ions, all recombining with negative oxygen clusters O(2)(-)(H(2)O)(n) (negative reactant ions) in a field-free reaction region, are measured and compared. For all experiments, we use a drift tube ion mobility spectrometer equipped with a non-radioactive electron gun for pulsed atmospheric pressure ionization of the analytes. Both, ionization and recombination times are controlled by the duty cycle and repetition rate of the electron emission from the electron gun. Thus, it is possible to investigate the ion loss caused by ion-ion-recombination depending on the recombination time defined as the time delay between the end of the electron emission and the ion injection into the drift tube. Furthermore, the effect of the initial total ion density in the reaction region on the ion-ion-recombination rate is investigated by varying the density of the emitted electrons. PMID:22977880

  17. A Micro-Orifice Volatilization Impactor coupled to a Chemical Ionization Mass Spectrometer for the detection of organic acids in atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Yatavelli, R. L.; Thornton, J. A.

    2007-12-01

    Significant uncertainties related to sources and removal processes of particulate organic matter persist due, in part, to a poor understanding of the molecular-level composition. To address these issues, we are developing a novel technique that couples a micro-orifice volatilization impactor (MOVI) to a chemical ionization mass spectrometer (CIMS) for fast, in situ measurements of specific organic acids expected to be in atmospheric particles. The MOVI-CIMS process has three steps: 1) aerosol collection by inertial impaction, 2) volatilization and sample transfer, and 3) chemical ionization and detection using a quadrupole mass spectrometer. We present results from laboratory characterization of two MOVI designs, one operating at low pressure (60 Torr) and the other at near ambient pressure. The low-pressure impactor has a theoretical cut point of 40nm while the atmospheric pressure impactor (API) has a theoretical cut point of 280nm with a pressure drop of less than 5%. We compare the advantages and disadvantages of these two designs in terms of typical atmospheric particle size distributions. Experimental tests of their theoretical cut-points are used to assess the importance of jet-to- plate distance and particle bounce. In addition, we demonstrate the utility of the MOVI-CIMS technique by employing it in studies of heterogeneous oxidation of particle organics and of secondary organic aerosol formation from biogenic hydrocarbon oxidation. Based on typical signal-to-noise ratio, the MOVI-CIMS demonstrates a detection limit of ~50 ng for monocarboxylic acids when using the LPI version and the iodide ion as a chemical ionization reagent. Preliminary results suggest even lower detection limits are possible with other reagent ions.

  18. Atmospheric pressure gas discharges for surface treatment

    Microsoft Academic Search

    K. Pochner; W. Neff; R. Lebert

    1995-01-01

    Dielectric barrier discharges (also called silent discharges) driven by high voltage at frequencies from 50 Hz to several kilohertz have been used for decades in plasma chemical processing of gases. In this paper the new concept of direct dielectric barrier discharges for surface treatment in the range of several hundred kilohertz is introduced, where the material being treated is used

  19. Matrix Assisted Ionization in Vacuum, a Sensitive and Widely Applicable Ionization Method for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah; Inutan, Ellen D.

    2013-05-01

    An astonishingly simple new method to produce gas-phase ions of small molecules as well as proteins from the solid state under cold vacuum conditions is described. This matrix assisted ionization vacuum (MAIV) mass spectrometry (MS) method produces multiply charged ions similar to those that typify electrospray ionization (ESI) and uses sample preparation methods that are nearly identical to matrix-assisted laser desorption/ionization (MALDI). Unlike these established methods, MAIV does not require a laser or voltage for ionization, and unlike the recently introduced matrix assisted ionization inlet method, does not require added heat. MAIV-MS requires only introduction of a crystalline mixture of the analyte incorporated with a suitable small molecule matrix compound such as 3-nitrobenzonitrile directly to the vacuum of the mass spectrometer. Vacuum intermediate pressure MALDI sources and modified ESI sources successfully produce ions for analysis by MS with this method. As in ESI-MS, ion formation is continuous and, without a laser, little chemical background is observed. MAIV, operating from a surface offers the possibility of significantly improved sensitivity relative to atmospheric pressure ionization because ions are produced in the vacuum region of the mass spectrometer eliminating losses associated with ion transfer from atmospheric pressure to vacuum. Mechanistic aspects and potential applications for this new ionization method are discussed.

  20. Atmospheric Pressure non-thermal plasmas for surface treatment of polymer films

    NASA Astrophysics Data System (ADS)

    Huang, Hsiao-Feng; Wen, Chun-Hsiang; Wei, Hsiao-Kuan; Kou, Chwung-Shan

    2006-10-01

    Interest has grown over the past few years in applying atmospheric pressure non-thermal plasmas to surface treatment. In this work, we used an asymmetric glow dielectric-barrier discharge (GDBD), at atmospheric pressure in nitrogen, to improve the surface hydrophilicity of three kinds of polymer films, biaxially oriented polypropylene (BOPP), polyimide (PI), and triacetyl cellulose (TAC). This set-up consists of two asymmetric electrodes covered by dielectrics. And to prevent the filamentary discharge occur, the frequency, gas flow rate and uniformity of gas flow distribution should be carefully controlled. The discharge performance is monitored through an oscilloscope, which is connected to a high voltage probe and a current monitor. The physical and chemical properties of polymer surfaces before and after GDBD treatment were analyzed via water contact angle (CA) measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) techniques.

  1. Atmospheric pressure microwave assisted heterogeneous catalytic reactions.

    PubMed

    Chemat-Djenni, Zoubida; Hamada, Boudjema; Chemat, Farid

    2007-01-01

    The purpose of the study was to investigate microwave selective heating phenomena and their impact on heterogeneous chemical reactions. We also present a tool which will help microwave chemists to answer to such questions as "My reaction yields 90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes under microwaves?" and to have an approximation of their reactions when conducted under microwaves with different heterogeneous procedures. This model predicting reaction kinetics and yields under microwave heating is based on the Arrhenius equation, in agreement with experimental data and procedures. PMID:17909495

  2. Cluster chemical ionization and deuterium exchange mass spectrometry in supersonic molecular Beams

    Microsoft Academic Search

    Shai Dagan; Aviv Amirav

    1996-01-01

    A cluster-based chemical ionization method has been developed that produces protonated molecular ions from molecules introduced\\u000a through a supersonic molecular beam interface. Mixed clusters of the analyte and a clustering agent (water or methanol) are\\u000a produced in the expansion region of the beam, and are subsequently ionized by “fly through” electron impact (EI) ionization,\\u000a which results in a mass spectrum

  3. Novel applications of atmospheric pressure plasma on textile materials

    NASA Astrophysics Data System (ADS)

    Cornelius, Carrie Elizabeth

    Various applications of atmospheric pressure plasma are investigated in conjunction with polymeric materials including paper, polypropylene non-woven fabric, and cotton. The effect of plasma on bulk and surface properties is examined by treating both cellulosic pulp and prefabricated paper with various plasma-gas compositions. After treatment, pulp is processed into paper and the properties are compared. The method of pulp preparation is found to be more significant than the plasma, but differences in density, strength, and surface roughness are apparent for the pulp vs. paper plasma treatments. The plasma is also used to remove sizes of PVA and starch from poly/cotton and cotton fabric respectively. In both cases plasma successfully removes a significant amount of size, but complete size removal is not achieved. Subsequent washes (PVA) or scouring (cotton) to remove the size are less successful than a control, suggesting the plasma is crosslinking the size that is not etched away. However, at short durations in cold water using an oxygen plasma, slightly more PVA is removed than with a control. For the starch sized samples, plasma and scouring are never as successful at removing starch as a conventional enzyme, but plasma improves dyeability without need for scouring. Plasma is also used to graft chemicals to the surface of polypropylene and cotton fabric. HTCC, an antimicrobial is grafted to polypropylene with successful grafting indicated by x-ray photoemission spectroscopy (XPS), dye tests, and Fourier transform infrared spectroscopy (FTIR). Antimicrobial activity of the grafted samples is also characterized. 3ATAC, a vinyl monomer is also grafted to polypropylene and to cotton. Additives including Mohr's salt, potassium persulfate, and diacrylate are assessed to increase yield. Successful grafting of 3ATAC is confirmed by XPS and dye testing. A combination of all three additives is identified as optimum for maximizing graft yield.

  4. Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies

    NASA Astrophysics Data System (ADS)

    Gans, Timo

    2012-10-01

    Non-equilibrium plasmas operated at ambient atmospheric pressure are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. This includes the unique opportunity to deliver short-lived highly reactive species such as atomic oxygen and atomic nitrogen. Reactive oxygen and nitrogen species can initiate a wide range of reactions in biochemical systems, both therapeutic and toxic. The toxicological implications are not clear, e.g. potential risks through DNA damage. It is anticipated that interactions with biological systems will be governed through synergies between two or more species. Suitable optimized plasma sources are improbable through empirical investigations. Quantifying the power dissipation and energy transport mechanisms through the different interfaces from the plasma regime to ambient air, towards the liquid interface and associated impact on the biological system through a new regime of liquid chemistry initiated by the synergy of delivering multiple energy carrying species, is crucial. The major challenge to overcome the obstacles of quantifying energy transport and controlling power dissipation has been the severe lack of suitable plasma sources and diagnostic techniques. Diagnostics and simulations of this plasma regime are very challenging; the highly pronounced collision dominated plasma dynamics at very small dimensions requires extraordinary high resolution - simultaneously in space (microns) and time (picoseconds). Numerical simulations are equally challenging due to the inherent multi-scale character with very rapid electron collisions on the one extreme and the transport of chemically stable species characterizing completely different domains. This presentation will discuss our recent progress actively combining both advance optical diagnostics and multi-scale computer simulations.

  5. Atmospheric-pressure-plasma nitriding of titanium alloy

    NASA Astrophysics Data System (ADS)

    Yoshimitsu, Yuki; Ichiki, Ryuta; Kasamura, Kotaro; Yoshida, Masashi; Akamine, Shuichi; Kanazawa, Seiji

    2015-03-01

    Atmospheric-pressure-plasma nitriding of titanium alloy Ti–6Al–4V has been achieved by using a pulsed-arc plasma jet with a N2/H2 gas mixture, where the plasma jet plume is sprayed onto the titanium surface under atmospheric pressure. We successfully formed a titanium nitride layer on the sample surface. Moreover, the diffusion layer was also formed, the hardness of which was increased from that of as-received titanium. The nitride layer growth was found to be diffusion-controlled, as in other conventional nitriding methods.

  6. Peptide Fragmentation Induced by Radicals at Atmospheric Pressure

    PubMed Central

    Vilkov, Andrey N.; Laiko, Victor V.; Doroshenko, Vladimir M.

    2009-01-01

    A novel ion dissociation technique, which is capable of providing an efficient fragmentation of peptides at essentially atmospheric pressure conditions, is developed. The fragmentation patterns observed often contain c-type fragments that are specific to ECD/ETD, along with the y-/b- fragments that are specific to CAD. In the presented experimental setup, ion fragmentation takes place within a flow reactor located in the atmospheric pressure region between the ion source and the mass spectrometer. According to a proposed mechanism, the fragmentation results from the interaction of ESI-generated analyte ions with the gas-phase radical species produced by a corona discharge source. PMID:19034885

  7. Determination of double bond position in conjugated dienes by chemical ionization mass spectrometry with isobutane

    Microsoft Academic Search

    Robert E. Doolittle; J. H. Tumlinson; A. Proveaux

    1985-01-01

    The chemical ionization (CI) mass spectra of a series of functionalized conjugated dienes, including aldehydes, alcohols, formates, acetates, and hydrocarbons were investigated to determine whether fragmentations occur that are characteristic of the position of the conjugated system within the hydrocarbon chain. CI with isobutane as ionizing gas produces structure-specific fragment ions with m\\/z ratios that can be used to locate

  8. Development of compact ion gun under atmospheric pressure X-rays

    NASA Astrophysics Data System (ADS)

    Hana, Nurul; Tsutsui, Hidenori; Matsutani, Takaomi; Hosokawa, Yoshinori

    2012-02-01

    A highly efficient and highly stable compact ion gun (less than 10 × 10 × 5 cm) operable under atmospheric pressure was developed for environmental measurements and materials technology applications. Soft X-ray ionization was used as an ion source. In this work, soft X-rays were generated from a beryllium/titanium target irradiated by 9 keV thermal electrons. For a nitrogen assist gas flow rate of 500 ml/min and an acceleration voltage of 3.9 kV, the highest average ion current was 1.34 nA and a current stability of ±6% over 10 min was obtained. A high frequency electric field was applied to the electrode in the X-ray ionization chamber in order to enhance the ion current. The ion current increased by a factor of 1.6 compared to the current in the absence of the high frequency electric field. The ion gun developed here was employed to deposit a silicon carbonitride (SiCN) film on silicon and copper substrates by using nitrogen ions and hexamethyldisilane under atmospheric pressure conditions. The deposition of a hydrogenated SiCO and SiCN mixture film was confirmed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.

  9. Negative chemical ionization studied of human and food chain contamination with xenobiotic chemicals.

    PubMed Central

    Dougherty, R C; Whitaker, M J; Smith, L M; Stalling, D L; Kuehl, D W

    1980-01-01

    Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasma, and human adipose tissue, were cleaned up by one of the following three cleanup procedures: (1) continuous liquid-liquid extraction steam distillation; (2) gel-permeation chromatography; and (3) adsorption on activated carbon followed by elution with toluene. The third procedure was used only for the examination of planar polychlorinated aromatic hydrocarbons in environmental samples. Using these techniques, we have found evidence for contamination of fish samples with polychloronaphthalenes, polychlorostyrenes, polychlorobiphenyls, polychlorodibenzofurans, and polychlorodibenzodioxins among other chemicals. The polychlorodibenzodioxins appeared only in the spectra of extracts of fish obtained from the Tittabawassee River at Midland Michigan. The polychlorodibenzofuran ions appeared in NCI mass spectra of fish that were significantly contaminated (above 2 ppm) with polychlorobiphenyls. Toxic substances occurring in human seminal plasma included pentachlorophenol, hexachlorobenzene, DDT metabolites, and polychlorobiphenyls. We have investigated toxic substances in human seminal plasma because of the apparent decrease in sperm density in U.S. males over the last 30 years. Results of screening human adipose tissue for contamination with xenobiotic chemicals have been largely coincident with result of the EPA human monitoring program. Polychlorobiphenyls, DDT metabolites, nonachlor, and chlordane have appeared in most samples examined. Detection limits for all of these chemicals were of the order of 1 ppb. PMID:7428739

  10. Hybrid Arc\\/Glow Microdischarges at Atmospheric Pressure and Their Use in Portable Systems for Liquid and Gas Sensing

    Microsoft Academic Search

    Bhaskar Mitra; Brandon Levey; Yogesh B. Gianchandani

    2008-01-01

    This paper reports on DC pulse-powered microdischarges in air at atmospheric pressure and their potential utility in chemical sensing. For electrode gaps of 50-100 mum, microdischarges take the form of a glow discharge, an arc discharge, or a hybrid of the two. Arc microdischarges have high optical intensity but suffer from high background emission. Glow microdischarges have low background emission,

  11. A study of the tropospheric oxidation of volatile organic compounds using chemical ionization mass spectrometry

    E-print Network

    Broekhuizen, Keith Edward, 1974-

    2002-01-01

    The mechanisms and kinetics of reactions important to the troposphere have been investigated using a high pressure, turbulent, discharge-flow technique coupled to a chemical ionization mass spectrometer. The ability to ...

  12. Preparation of nanodiamonds from carbon nanoparticles at atmospheric pressure.

    PubMed

    Kamali, Ali Reza; Fray, Derek J

    2015-03-17

    A route for producing diamond nanocrystals is reported in this paper. Li2CO3 containing carbon nanostructures synthesised in molten LiCl were transformed to nanodiamonds by simple heating at atmospheric pressure, far less severe conditions than conventional processes. The method presented offers the possibility of bulk production. PMID:25650151

  13. From Submicrosecond to Nanosecond-Pulsed Atmospheric-Pressure Plasmas

    Microsoft Academic Search

    Felipe Iza; James L. Walsh; Michael G. Kong

    2009-01-01

    We have developed a time-hybrid computational model to study pulsed atmospheric-pressure discharges and compared simulation results with experimental data. Experimental and computational results indicate that increasing the applied voltage results in faster ignition of the discharge and an increase in the mean electron energy, opening the door to tunable plasma chemistry by means of pulse shaping. Above a critical electric

  14. Ion transport through capillary atmospheric pressure interfaces of mass spectrometers

    Microsoft Academic Search

    Sandilya Venkata Bhaskara Garimella

    2009-01-01

    The transmission efficiency of ions\\/charged droplets traveling through typical atmospheric pressure interfaces (API) of mass spectrometers is investigated to advance the understanding of charge transport in micro capillaries. The charge transfer efficiency for various capillary dimensions and same flow conductance was focused upon. Quantitative measurements of current transmitted through the API and the current lost to the wall of the

  15. Atmospheric Pressure Infrared MALDI Imaging Mass Spectrometry for Plant Metabolomics

    E-print Network

    Vertes, Akos

    #12;Atmospheric Pressure Infrared MALDI Imaging Mass Spectrometry for Plant Metabolomics Yue Li MALDI mass spectrometry (AP IR-MALDI) was assessed for plant metabolomics studies. Tissue sections from plant organs, including flowers, ovaries, aggregate fruits, fruits, leaves, tubers, bulbs, and seeds

  16. Is atmospheric pressure change an Independent risk factor for hemoptysis?

    PubMed Central

    Araz, Omer; Ucar, Elif Yilmazel; Akgun, Metin; Aydin, Yener; Meral, Mehmet; Saglam, Leyla; Kaynar, Hasan; Gorguner, Ali Metin

    2014-01-01

    Objective: Hemoptysis is one of the most important and challenging symptoms in pulmonary medicine. Because of the increased number of patients with hemoptysis in certain periods of the year, we aimed to investigate whether atmospheric changes have an effect on the development of hemoptysis with or without a secondary cause. Methods: The data of patients presenting with hemoptysis between January 2006 and December 2011 were analyzed. Data on the daily atmospheric pressure (hectopascal, hPa), relative humidity (%), and temperature (o C) during that time were obtained. Results: A total of 232 patients with hemoptysis, 145 male (62.5%) and 87 female (37.5%) with an average age of 48.1(±17.6), were admitted to our hospital between 2006 and 2011. The highest admission rates were in the spring season, the highest in May (n=37, 15.9%), and the lowest admission rates were in December (n=10, 4.3%). A statistically significant negative correlation was found between the number of hemoptysis cases and mean atmospheric pressure but no relative humidity or outdoor temperature. Conclusion: Hemoptysis is very much influenced by weather factors; in particular, low atmospheric pressures significantly affect the development of hemoptysis. Fluctuations in atmospheric pressure may also play a role in hemoptysis. PMID:24948987

  17. Atmospheric pressure and suicide attempts in Helsinki, Finland

    NASA Astrophysics Data System (ADS)

    Hiltunen, Laura; Ruuhela, Reija; Ostamo, Aini; Lönnqvist, Jouko; Suominen, Kirsi; Partonen, Timo

    2012-11-01

    The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods ( P < 0.001), and may explain the clustering of suicide attempts. Men seem to be more vulnerable to attempt suicide under low atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects.

  18. Atmospheric pressure and suicide attempts in Helsinki, Finland.

    PubMed

    Hiltunen, Laura; Ruuhela, Reija; Ostamo, Aini; Lönnqvist, Jouko; Suominen, Kirsi; Partonen, Timo

    2012-11-01

    The influence of weather on mood and mental health is commonly debated. Furthermore, studies concerning weather and suicidal behavior have given inconsistent results. Our aim was to see if daily weather changes associate with the number of suicide attempts in Finland. All suicide attempts treated in the hospitals in Helsinki, Finland, during two separate periods, 8 years apart, were included. Altogether, 3,945 suicide attempts were compared with daily weather parameters and analyzed with a Poisson regression. We found that daily atmospheric pressure correlated statistically significantly with the number of suicide attempts, and for men the correlation was negative. Taking into account the seasonal normal value during the period 1971-2000, daily temperature, global solar radiation and precipitation did not associate with the number of suicide attempts on a statistically significant level in our study. We concluded that daily atmospheric pressure may have an impact on suicidal behavior, especially on suicide attempts of men by violent methods (P?atmospheric pressure and women under high atmospheric pressure. We show only statistical correlations, which leaves the exact mechanisms of interaction between weather and suicidal behavior open. However, suicidal behavior should be assessed from the point of view of weather in addition to psychiatric and social aspects. PMID:22278192

  19. Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for

    E-print Network

    Greifswald, Ernst-Moritz-Arndt-Universität

    Atmospheric Pressure Plasma Jet Treatment of Polyethylene Surfaces for Adhesion Improvement Uwe] The pretreatment modifies the surface properties of the substrate, thereby improving the adhesion strength parts of a substrate selectively.[3,4] Also, in contrast to most corona treatments (and dielectric

  20. The Water Table As Affected by Atmospheric Pressure

    Microsoft Academic Search

    A. J. Peck

    1960-01-01

    In the common situation where air is entrapped in the water, the water table height will vary with atmospheric pressure. The magnitude of this effect must be known before water-table changes can be related with any precision to other factors such as evapo- transpiration, infiltration, and drainage. A theory of this effect is developed and the influences of hysteresis and

  1. Gravity and Atmospheric Pressure Effects on Crater Formation in Sand

    Microsoft Academic Search

    S. W. Johnson; J. A. Smith; E. G. Franklin; L. K. Moraski; D. J. Teal

    1969-01-01

    An experimental investigation was conducted to determine the effects of varying gravity and atmospheric pressure on the size of small explosion craters formed in cohesionless sand. The explosives used were commercially available squibs and caps and a linear detonating cord. Gravity was varied by flying the test container in an aircraft through carefully controlled maneuvers to simulate 0.17, 0.38, and

  2. Global Atmospheric Pressure Effects of the October 30, 1961, Explosion

    Microsoft Academic Search

    H. Wexler; W. A. Hass

    1962-01-01

    The atmospheric pressure waves set off by the explosion of October 30, 1961, were traced over a large portion of the world, including the antipodes in the Antarctic, by means of analyses of available ordinary microbarograph records. The observed geographic variations in propagation speed and maximum amplitude are examined with the aid of air density and wind analyses. Comparison is

  3. ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES

    EPA Science Inventory

    The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly unde...

  4. Carbonation of epoxy methyl soyate at atmospheric pressure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbonated methyl soyates were prepared from epoxy methyl soyate by the introduction of carbon dioxide at the oxirane position. Carbonation was performed with carbon dioxide gas by sparging carbon dioxide through the epoxy esters at atmospheric pressure in the presence of tetrabutylammonium bromide...

  5. Mechanisms for negative reactant ion formation in an atmospheric pressure corona discharge

    SciTech Connect

    Ewing, Robert G.; Waltman, Melanie J.

    2009-06-02

    In an effort to better understand the formation of negative reactant ions in air produced by an atmospheric pressure corona discharge source, the neutral vapors generated by the corona were introduced in varying amounts into the ionization region of an ion mobility spectrometer/mass spectrometer containing a 63Ni ionization source. With no discharge gas the predominant ions were O2- , however, upon the introduction of low levels of discharge gas the NO2- ion quickly became the dominant species. As the amount of discharge gas increased the appearance of CO3- was observed followed by the appearance of NO3-. At very high levels, NO3- species became effectively the only ion present and appeared as two peaks in the IMS spectrum, NO3- and the NO3-•HNO3 adduct, with separate mobilities. Since explosive compounds typically ionize in the presence of negative reactant ions, the ionization of an explosive, RDX, was examined in order to investigate the ionization properties with these three primary ions. It was found that RDX forms a strong adduct with both NO2- and NO3- with reduced mobility values of 1.49 and 1.44 cm2V-1s-1, respectively. No adduct was observed for RDX with CO3- although this adduct has been observed with a corona discharge mass spectrometer. It is believed that this adduct, although formed, does not have a sufficiently long lifetime (greater than 10 ms) to be observed in an ion mobility spectrometer.

  6. Chemical ionization of pentacarbonylrhenium halides in vapor of water, methanol, or ethanol

    SciTech Connect

    Bogdanov, V.A.; Savel'ev, Y.I.; Shchelokov, R.N.

    1986-05-01

    This paper studies the behavior of pentacarbonylrhenium (PCR) halides in chemical ionization in water, methanol, ethanol, or acetone in the vapor phase. The mass spectra is shown for the chemical ionization of the mixture of PCR chloride and PCR bromide, normalized on the maximum-intensity peak. The study shows that the most active group in the complexes Re(CO)/sub 5/X, susceptible to detachment or replacement in ionized vapor of water or certain simple alcohols, is a halogen atom that is omega-bonded to the metal atom. Data on the chemical ionization of halogen-substituted organic compounds also indicate that the halogen atoms in these compounds are quite readily split off, usually in the form of the hydrogen halide.

  7. Flow injection of liquid samples to a mass spectrometer with ionization under vacuum conditions: a combined ion source for single-photon and electron impact ionization.

    PubMed

    Schepler, Claudia; Sklorz, Martin; Passig, Johannes; Famiglini, Giorgio; Cappiello, Achille; Zimmermann, Ralf

    2013-09-01

    Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI) are the most important techniques for the ionization of liquid samples. However, working under atmospheric pressure conditions, all these techniques involve some chemical rather than purely physical processes, and therefore, side reactions often yield to matrix-dependent ionization efficiencies. Here, a system is presented that combines both soft single-photon ionization (SPI) and hard 70 eV electron impact ionization (EI) of dissolved compounds under vacuum conditions. A quadrupole mass spectrometer was modified to enable direct EI, a technique developed by Cappiello et al. to obtain library-searchable EI mass spectra as well as soft SPI mass spectra of sample solutions. An electron beam-pumped rare gas excimer lamp working at 126 nm was used as well as a focusable vacuum UV light source for single-photon ionization. Both techniques, EI and SPI, were applied successfully for flow injection experiments providing library-matchable EI fragment mass spectra and soft SPI mass spectra, showing dominant signals for the molecular ion. Four model compounds were analyzed: hexadecane, propofol, chlorpropham, and eugenol, with detection limits in the picomolar range. This novel combination of EI and SPI promises great analytical benefits, thanks to the possibility of combining database alignment for EI data and molecular mass information provided by SPI. Possible applications for the presented ionization technology system are a matrix-effect-free detection and a rapid screening of different complex mixtures without time-consuming sample preparation or separation techniques (e.g., for analysis of reaction solutions in combinatorial chemistry) or a switchable hard (EI) and soft (SPI) MS method as detection step for liquid chromatography. PMID:23812882

  8. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    SciTech Connect

    Li Guo; Li Heping; Wang Sen; Sun Wenting; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Wang Liyan; Zhao Hongxin; Xing Xinhui [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2008-06-02

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  9. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    NASA Astrophysics Data System (ADS)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  10. Surface properties and hydrophobic recovery of polymers treated by atmospheric-pressure plasma

    NASA Astrophysics Data System (ADS)

    Borcia, C.; Punga, I. L.; Borcia, G.

    2014-10-01

    This paper provides an analysis on the relation between plasma effects on polymers exposed to inert gas atmospheric-pressure plasma, polymer structure characteristics and surface recovery during post-processing ageing. Polymers offering variety of structure, functionality, degree of oxidation, polarity, crystallinity are tested, using contact angle, XPS, XRD and solvent absorption measurement, thus exploring the relationship linking the surface polarity, the chemical structure and composition contribution in the combined functionalization/crosslinking surface modification mechanisms of plasma-exposed polymers. The limiting level of modification attainable, the surface stability and the factors controlling these are examined, concluding on the plasma capacity to provide operational stability for modified polymer surfaces.

  11. Experimental and Modeling Study of Premixed Atmospheric-Pressure Dimethyl Ether?Air Flames

    Microsoft Academic Search

    E. W. Kaiser; T. J. Wallington; M. D. Hurley; J. Platz; H. J. Curran; W. J. Pitz; C. K. Westbrook

    2000-01-01

    Chemical species profiles have been measured at atmospheric pressure for two dimethyl ether (DME)-air flat flames having fuel-air equivalence ratios of 0.67 and 1.49. The samples, obtained with an uncooled quartz probe, were analyzed by either gas chromatography or Fourier transform infrared (FTIR) spectroscopy for CH4, C2H2, C2H4, C2H6, C3H8, DME, CO, CO2, O2, CH2O, and formic acid. A pneumatic

  12. Application of an atmospheric pressure sampling mass spectrometer to chlorination reactions

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.

    1986-01-01

    An atmospheric pressure mass spectrometric sampling system, based on a free jet expansion was used to study certain M-Cl-O reactions at high temperatures. The apparatus enables the volatile species from a 1-atm chemical process to be directly identified with a mass spectrometer which operates at approx. 10 to the minus 8th power torr. Studies for both pure metals and alloys are discussed. It is shown that this mass spectrometer system aids in identifying the volatile species, and provides fundamental information on the reaction mechanism.

  13. Assessment of the various ionization methods in the analysis of metal salen complexes by mass spectrometry.

    PubMed

    S?omi?ska, Beata; Cha?adaj, Wojciech; Danikiewicz, Witold

    2014-05-01

    Metal salen complexes are one of the most frequently used catalysts in enantioselective organic synthesis. In the present work, we compare a series of ionization methods that can be used for the mass spectral analysis of two types of metalosalens: ionic complexes (abbreviated as Com(+)X(-)) and neutral complexes (NCom). These methods include electron ionization and field desorption (FD) which can be applied to pure samples and atmospheric pressure ionization techniques: electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) which are suitable for solutions. We found that FD is a method of choice for recording molecular ions of the complexes containing even loosely bonded ligands. The results obtained using atmospheric pressure ionization methods show that the results depend mainly on the structure of metal salen complex and the ionization method. In ESI spectra, Com(+) ions were observed, while in APCI and APPI spectra both Com(+) and [Com?+?H](+) ions are observed in the ratio depending on the structure of the metal salen complex and the solvent used in the analysis. For complexes with tetrafluoroborate counterion, an elimination of BF3 took place, and ions corresponding to complexes with fluoride counterion were observed. Experiments comparing the relative sensitivity of ESI, APCI and APPI (with and without a dopant) methods showed that for the majority of the studied complexes ESI is the most sensitive one; however, the sensitivity of APCI is usually less than two times lower and for some compounds is even higher than the sensitivity of ESI. Both methods show very high linearity of the calibration curve in a range of about 3 orders of magnitude of the sample concentration. PMID:24809900

  14. Removal of paper microbial contamination by atmospheric pressure DBD discharge

    NASA Astrophysics Data System (ADS)

    Vrajova, J.; Chalupova, L.; Novotny, O.; Cech, J.; Krcma, F.; Stahel, P.

    2009-08-01

    In this paper the removal of the microbial contamination from paper material using the plasma treatment at atmospheric pressure is investigated. The Aspergillus niger has been chosen as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. Dielectric barrier discharge (DBD) operated at atmospheric pressure was used for the paper sterilization. The working gas (nitrogen, argon and helium), plasma exposition time and the plasma power density were varied in order to see the effect of the plasma treatment on the fungi removal. After the treatment, the microbial abatement was evaluated by the standard plate count method. This proved a positive effect of the DBD plasma treatment on fungi removal. Morphological and colorimetric changes of paper substrate after plasma treatment were also investigated.

  15. Cellular membrane collapse by atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  16. Atmospheric-pressure plasma sources for biomedical applications

    NASA Astrophysics Data System (ADS)

    Park, G. Y.; Park, S. J.; Choi, M. Y.; Koo, I. G.; Byun, J. H.; Hong, J. W.; Sim, J. Y.; Collins, G. J.; Lee, J. K.

    2012-08-01

    Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented.

  17. Cellular membrane collapse by atmospheric-pressure plasma jet

    SciTech Connect

    Kim, Kangil; Sik Yang, Sang, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Jun Ahn, Hak; Lee, Jong-Soo, E-mail: jsjlee@ajou.ac.kr, E-mail: ssyang@ajou.ac.kr [Department of Biological Sciences, Ajou University, Suwon 443-749 (Korea, Republic of)] [Department of Biological Sciences, Ajou University, Suwon 443-749 (Korea, Republic of); Lee, Jae-Hyeok; Kim, Jae-Ho [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of)] [Department of Molecular Science and Technology, Ajou University, Suwon 443-749 (Korea, Republic of)

    2014-01-06

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  18. Atmospheric-pressure guided streamers for liposomal membrane disruption

    SciTech Connect

    Svarnas, P.; Aleiferis, Sp. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); Matrali, S. H. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Gazeli, K. [High Voltage Laboratory, Department of Electrical and Computer Engineering, University of Patras, Rion 26504 (Greece); IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Clement, F. [IPREM-LCABIE, Plasmas et Applications, UPPA, 64000 Pau (France); Antimisiaris, S. G. [Pharmaceutical Technology Laboratory, Department of Pharmacy, University of Patras, Rion 26504 (Greece); Institute of Chemical Engineering Sciences (ICES)-FORTH, Rion 26504 (Greece)

    2012-12-24

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  19. Atmospheric pressure Eberlin transacetalization reactions in the heterogeneous liquid/gas phase

    NASA Astrophysics Data System (ADS)

    Augusti, Rodinei; Chen, Hao; Eberlin, Livia Schiavinato; Nefliu, Marcela; Cooks, R. Graham

    2006-07-01

    The Eberlin reaction, the ionic transacetalization of cyclic acetals and analogues with acylium and related ions, is demonstrated in the course of ion/molecule reactions at atmospheric pressure. Selected gaseous acetals (1,3-dioxolane, 2-methyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 1,3-dioxane, and 1,3,5-trioxane) react efficiently with the (CH3)2NCO+ acylium ion, generated by electrosonic spray ionization (ESSI) of an aqueous/methanol solution of tetramethylurea (TMU), to furnish the characteristic cyclic ionic acetals, the Eberlin products, in moderate to high yields. It is proposed that acylium ions on the surface of the ESSI-generated droplets interact with gaseous neutral reagentsE The Eberlin products dissociate exclusively to re-form the reactant (CH3)2NCO+ acylium ion upon collision-induced dissociation (CID), confirming their structures. The intact adduct, i.e., acylium ion plus neutral reagent (the stable precursor of the Eberlin product), is observed in these experiments whereas it is not observed in studies of the same Eberlin reactions under conventional reduced pressure ion/molecule reaction conditions. It is suggested that under atmospheric pressure conditions these intact adducts are likely stabilized through deactivation via collision with buffer gas.

  20. Self-pulsing discharges in pre-heated air at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Janda, Mário; Machala, Zdenko; Dvon?, Lukáš; Lacoste, Deanna; Laux, Christophe O.

    2015-01-01

    The paper presents investigations of self-pulsing discharges in atmospheric pressure air pre-heated to 300–1000 K. Despite using a direct-current power supply, two self-pulsing discharge regimes, a repetitive transient spark (TS) and a repetitive streamer (RS) were generated. The pulse repetition frequency, on the order of a few kHz, can be controlled by adjusting the generator voltage. The TS is a discharge initiated by a streamer, followed by a short (tens of ns) spark current pulse (˜ 1 A), associated with the total discharging of the internal capacity of the electric circuit. The TS is suitable for the study of ‘memory’ effects (pre-heating, pre-ionization) on the mechanisms of streamer-to-spark transition and electrical breakdown in atmospheric pressure air. The TS regime was stable below ˜600 K. Above ˜600 K, a stable repetitive streamer (RS) regime was observed. In this regime, the breakdown and spark did not occur. After the initial streamer, the internal capacity of the electrical circuit discharged partially. With further pre-heating of the gas, the stable TS appeared again at ˜1000 K.

  1. Atmospheric pressure imaging mass spectrometry of drugs with various ablating lasers

    NASA Astrophysics Data System (ADS)

    Moshkunov, K. A.; Alimpiev, S. S.; Grechnikov, A. A.; Nikifirov, S. M.; Pento, A. V.; Simanovsky, Ya O.

    2014-12-01

    The atmospheric pressure mass spectrometric detection efficiency of organic species (tofisopam and verapamil) was measured by means of the laser ablation of dried solution drops containing known amount of the analyte. Ablated molecules were ionized by an atmospheric pressure laser plasma cell and then introduced in the TOF mass-spectrometer. The spot was formed by dripping 2 ?l of solution on the stainless steel substrate and consequent drying. Then it was scanned by an intense ablating beam of various lasers (CO2, Nd:YAG and femtosecond fiber laser) until the spot was completely eroded during the non-stop MS-analysis of ablated material. The sensitivity was defined as the ratio of the total ion current integral of the relevant mass peaks to the amount of molecules in the spot. All the tested lasers are suitable for the ablation and subsequent MS-detection of organic species in dried solution spots given enough power deposition is provided. The measured sensitivity values reach 0.1 ions/fg of tested analytes.

  2. Influence of Atmospheric Pressure and Composition on LIBS

    SciTech Connect

    Jeremy J. Hatch [Pacific Univ., Forest Grove, OR (United States). Dept. of Chemistry; Jill R. Scott [Idaho National Laboratory (INL), Idaho Falls, ID (United States). Chemical and Radiation Measurement; Effenberger, A. J. Jr. [Univ. of California, San Diego, CA (United States). Center for Energy Research

    2014-03-01

    Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to higher resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample. Increasing the number of photons interacting with the sample surface results in increased ablation, which can lead to increased intensity. The composition of the background gas has been shown to greatly influence the observed LIBS spectra by altering the plasma temperature, electron density, mass removal, and plasma shielding that impact the emission intensity and peak resolution. It has been reported that atmospheric Ar results in the highest plasma temperature and electron density, while a He atmosphere results in the lowest plasma temperatures and electron density. Studying temporal data, it was also found that Ar had the slowest decay of both electron density and plasma temperature, while He had the fastest decay in both parameters. The higher plasma temperature and electron density results in an increase in line broadenin, or poor resolution, for Ar compared to He. A rapidly developing LIBS plasma with a sufficient amount of electrons can absorb a significant portion of the laser pulse through inverse Bremsstahlung. Ar (15.8 eV ) is more easily ionized than He (24.4 eV). The breakdown threshold for He at 760 Torr is approximately 3 times greater than Ar and approximately 5 times greater at 100 Torr. The lower breakdown threshold in Ar, compared to He, creates an environment favorable for plasma shielding, which reduces sample vaporization and leads to a weaker LIBS signal.

  3. Electron impact, electron capture negative ionization and positive chemical ionization mass spectra of organophosphorus flame retardants and plasticizers.

    PubMed

    Ma, Yuning; Hites, Ronald A

    2013-08-01

    Phosphate esters are important commercial products that have been used both as flame retardants and as plasticizers. To analyze these compounds by gas chromatographic mass spectrometry, it is important to understand the mass spectra of these compounds using various ionization modes. This paper is a systematic overview of the electron impact (EI), electron capture negative ionization (ECNI) and positive chemical ionization (PCI) mass spectra of 13 organophosphate esters. These data are useful for developing and optimizing analytical measurements. The EI spectra of these 13 compounds are dominated by ions such as H4 PO4 (+) , (M?-?Cl)(+) , (M?-?CH2 Cl)(+) or (M)(+) depending on specific chemical structures. The ECNI spectra are generally dominated by (M?-?R)(-) . The PCI spectra are mainly dominated by the protonated molecular ion (M?+?H)(+) . The branching of the alkyl substituents, the halogenation of the substituents and, for aromatic phosphate esters, ortho alkylation of the ring are all significant factors controlling the details of the fragmentation processes. EI provides the best sensitivity for the quantitative measurement of these compounds, but PCI and ECNI both have considerable qualitative selectivity. PMID:23893640

  4. A helium freeze-out cleaner operating at atmospheric pressure

    Microsoft Academic Search

    J. P. Dauvergne; D. Delikaris; F. Haug; S. Knoops

    1994-01-01

    A low pressure helium purification system has been designed at CERN. The helium gas recovered by means of a set of vacuum pumps from subatmospheric cryogenic circuits is cleaned at purity levels permitting direct re-liquefaction into the main cryo-plant cycle. The gas to be cleaned is close to ambient temperature and atmospheric pressure. It is cooled down to 33K by

  5. Beta-type Stirling engine operating at atmospheric pressure

    Microsoft Academic Search

    Serdar Yucesu; Tolga Topgul; Melih Okur

    2005-01-01

    In this study, a beta-type Stirling engine, with a 192 cc total swept-volume, was manufactured and its performance tested at atmospheric pressure. The hot-source temperature is chosen as a fundamental parameter of the experimental study. Experiments were performed with an electrical heater at 800, 900 and 1000 °C temperatures. Torque and output-power variations were obtained for different engine speeds. The

  6. Reaction mechanism of TEOS and O3 atmospheric pressure CVD

    Microsoft Academic Search

    K. Fujino; Y. Nishimoto; N. Tokumasu; K. Maeda

    1991-01-01

    The reaction mechanism of TEOS\\/O3 atmospheric pressure CVD was studied for dependence of deposition rate on base material, and for step coverage. Base material dependence of TEOS\\/USG, PSG, BSG and BPSG (on silicon and thermal oxide) was studied. Lower deposition rates and poorer quality of TEOS\\/USG films have been obtained on more hydrophilic substrate surface with high ozone concentration. The

  7. Pulsed Atmospheric-Pressure Cold Plasma for Endodontic Disinfection

    Microsoft Academic Search

    Chunqi Jiang; Meng-Tse Chen; Christoph Schaudinn; Amita Gorur; P. Thomas Vernier; J. William Costerton; David E. Jaramillo; Parish P. Sedghizadeh; Martin A. Gundersen

    2009-01-01

    A new plasma dental probe (PDP), powered with 4-6-kV ~100-ns electric pulses at repetition rates of up to 2 kHz, generates a room-temperature > 2-cm-long ~2-mm-diameter plasma plume at ambient atmospheric pressure. The shape of the plasma plume depends on the gas flow rate and the pulse voltage. Growth of Bacillus atrophaeus on nutrient agar plates is completely inhibited by

  8. Double streamer phenomena in atmospheric pressure low frequency corona plasma

    SciTech Connect

    Kim, Dan Bee; Jung, H.; Gweon, B.; Choe, Wonho [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2010-07-15

    Time-resolved images of an atmospheric pressure corona discharge, generated at 50 kHz in a single pin electrode source, show unique positive and negative corona discharge features: a streamer for the positive period and a glow for the negative period. However, unlike in previous reports of dc pulse and low frequency corona discharges, multistreamers were observed at the initial time stage of the positive corona. A possible physical mechanism for the multistreamers is suggested.

  9. Abatement of perfluorinated compounds using microwave plasmas at atmospheric pressure

    Microsoft Academic Search

    Y. Kabouzi; M. Moisan; J. C. Rostaing; C. Trassy; D. Guérin; D. Kéroack; Z. Zakrzewski

    2003-01-01

    Microwave plasmas sustained at atmospheric pressure, for instance by electromagnetic surface waves, can be efficiently used to abate greenhouse-effect gases such as perfluorinated compounds. As a working example, we study the destruction and removal efficiency (DRE) of SF6 at concentrations ranging from 0.1% to 2.4% of the total gas flow where N2, utilized as a purge gas, is the carrier

  10. Atmospheric pressure fluctuations and oxygen enrichment in waste tanks

    SciTech Connect

    Kurzeja, R.J.; Weber, A.H.

    1993-07-01

    During In-Tank Precipitation (ITP) processing radiolytic decomposition of tetraphenylborate and water can produce benzene and hydrogen, which, given sufficiently high oxygen concentrations, can deflagrate. To prevent accumulations of benzene and hydrogen and avoid deflagration, continuous nitrogen purging is maintained. If the nitrogen purging is interrupted by, for example, a power failure, outside air will begin to seep into the tank through vent holes and cracks. Eventually a flammable mixture of benzene, hydrogen, and oxygen will occur (deflagration). However, this process is slow under steady-state conditions (constant pressure) and mechanisms to increase the exchange rate with the outside atmosphere must be considered. The most important mechanism of this kind is from atmospheric pressure fluctuations in which an increase in atmospheric pressure forces air into the tank which then mixes with the hydrogen-benzene mixture. The subsequent decrease in atmospheric pressure causes venting from the tank of the mixture -- the net effect being an increase in the tank`s oxygen concentration. Thus, enrichment occurs when the atmospheric pressure increases but not when the pressure decreases. Moreover, this natural atmospheric {open_quotes}pumping{close_quotes} is only important if the pressure fluctuations take place on a time scale longer than the characteristic mixing time scale (CMT) of the tank. If pressure fluctuations have a significantly higher frequency than the CMT, outside air will be forced into the tank and then out again before any significant mixing can occur. The CMT is not known for certain, but is estimated to be between 8 and 24 hours. The purpose of this report is to analyze yearly pressure fluctuations for a five year period to determine their statistical properties over 8 and 24-hour periods. The analysis also includes a special breakdown into summer and winter seasons and an analysis of 15-minute data from the SRTC Climatology Site.

  11. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    NASA Astrophysics Data System (ADS)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  12. Quality characteristics of the radish grown under reduced atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Levine, Lanfang H.; Bisbee, Patricia A.; Richards, Jeffrey T.; Birmele, Michele N.; Prior, Ronald L.; Perchonok, Michele; Dixon, Mike; Yorio, Neil C.; Stutte, Gary W.; Wheeler, Raymond M.

    This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORACFL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.

  13. Plant adaptation to low atmospheric pressures: potential molecular responses

    NASA Technical Reports Server (NTRS)

    Ferl, Robert J.; Schuerger, Andrew C.; Paul, Anna-Lisa; Gurley, William B.; Corey, Kenneth; Bucklin, Ray

    2002-01-01

    There is an increasing realization that it may be impossible to attain Earth normal atmospheric pressures in orbital, lunar, or Martian greenhouses, simply because the construction materials do not exist to meet the extraordinary constraints imposed by balancing high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow plants at reduced atmospheric pressure. Yet current understanding of plant growth at low pressures is limited to just a few experiments and relatively rudimentary assessments of plant vigor and growth. The tools now exist, however, to make rapid progress toward understanding the fundamental nature of plant responses and adaptations to low pressures, and to develop strategies for mitigating detrimental effects by engineering the growth conditions or by engineering the plants themselves. The genomes of rice and the model plant Arabidopsis thaliana have recently been sequenced in their entirety, and public sector and commercial DNA chips are becoming available such that thousands of genes can be assayed at once. A fundamental understanding of plant responses and adaptation to low pressures can now be approached and translated into procedures and engineering considerations to enhance plant growth at low atmospheric pressures. In anticipation of such studies, we present here the background arguments supporting these contentions, as well as informed speculation about the kinds of molecular physiological responses that might be expected of plants in low-pressure environments.

  14. Laser Isotope Separation in Atomic Vapour:. PhotoChemical Method VS. PhotoIonization One

    Microsoft Academic Search

    P. A. Bokhan; N. V. Fateyev; D. E. Zakrevskiy; V. V. Buchanov; M. A. Kazaryan

    2010-01-01

    Two methods of laser isotope separation in atomic vapour are compared. The first of them is a well developed Photo-ionization method. The other method is based on isotope-selective excitation of long-living atomic states and subsequent chemical reaction of excited atom with special reagents. It is shown that this method has some principal advantages compared to Photo-ionization method.

  15. Optimization of the mass spectrometric analysis of triacylglycerols using negative-ion chemical ionization with ammonia

    Microsoft Academic Search

    Päivi Laakso; Heikki Kallio

    1996-01-01

    Conditions for the mass spectrometric analysis of triacylglycerols,via direct exposure probe, with ammonia negative-ion chemical ionization were optimized. Triacylglycerols were most favorably\\u000a ionized, using the reactant gas pressure of approximately 8500 mtorr at the ion source temperature of 200°C with the instrumentation\\u000a used. Abundant [M-H]? ions were produced under these conditions without the formation of [M+35]? cluster ions, which would

  16. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure ?-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  17. Simulations of nanosecond-pulsed dielectric barrier discharges in atmospheric pressure air

    SciTech Connect

    Soo Bak, Moon; Cappelli, Mark A. [Mechanical Engineering Department, Stanford University, Stanford, California 94305 (United States)

    2013-03-21

    This paper describes simulations of nanosecond pulse plasma formation between planer electrodes covered by dielectric barriers in air at atmospheric pressure and 340 K. The plasma formation process starts as electrons detach from negative ions of molecular oxygen that are produced from the previous discharge pulse. An ionization front is found to form close to the positively biased electrode and then strengthens and propagates towards the grounded electrode with increasing gap voltage. Charge accumulation and secondary emission from the grounded electrode eventually lead to sheath collapse. One interesting feature is a predicted reversal in gap potential due to the accumulated charge, even when there is no reversal in applied potential. The simulation results are compared to recent measurement of mid-gap electric field under the same discharge conditions [Ito et al., Phys. Rev. Lett. 107, 065002 (2011)].

  18. Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography\\/mass spectrometry and gas chromatography\\/flame ionization detection

    Microsoft Academic Search

    Miroslav Lísa; Kate?ina Netušilová; Lukáš Fran?k; Hana Dvo?áková; Vladimír Vrkoslav; Michal Hol?apek

    2011-01-01

    Fatty acid (FA) and triacylglycerol (TG) composition of natural oils and fats intake in the diet has a strong influence on the human health and chronic diseases. In this work, non-aqueous reversed-phase (NARP) and silver-ion high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection and gas chromatography with flame-ionization detection (GC\\/FID) and mass spectrometry detection are used for

  19. Synthetic oligomer analysis using atmospheric pressure photoionization mass spectrometry at different photon energies.

    PubMed

    Desmazières, Bernard; Legros, Véronique; Giuliani, Alexandre; Buchmann, William

    2014-01-15

    Atmospheric pressure photoionization (APPI) followed by mass spectrometric detection was used to ionize a variety of polymers: polyethylene glycol, polymethyl methacrylate, polystyrene, and polysiloxane. In most cases, whatever the polymer or the solvent used (dichloromethane, tetrahydrofuran, hexane, acetone or toluene), only negative ion mode produced intact ions such as chlorinated adducts, with no or few fragmentations, in contrast to the positive ion mode that frequently led to important in-source fragmentations. In addition, it was shown that optimal detection of polymer distributions require a fine tuning of other source parameters such as temperature and ion transfer voltage. Series of mass spectra were recorded in the negative mode, in various solvents (dichloromethane, tetrahydrofuran, hexane, toluene, and acetone), by varying the photon energy from 8eV up to 10.6eV using synchrotron radiation. To these solvents, addition of a classical APPI dopant (toluene or acetone) was not necessary. Courtesy of the synchrotron radiation, it was demonstrated that the photon energy required for an efficient ionization of the polymer was correlated to the ionization energy of the solvent. As commercial APPI sources typically use krypton lamps with energy fixed at 10eV and 10.6eV, the study of the ionization of polymers over a wavelength range allowed to confirm and refine the previously proposed ionization mechanisms. Moreover, the APPI source can efficiently be used as an interface between size exclusion chromatography or reverse phase liquid chromatography and MS for the study of synthetic oligomers. However, the photoionization at fixed wavelength of polymer standards with different molecular weights showed that it was difficult to obtain intact ionized oligomers with molecular weights above a few thousands. PMID:24370106

  20. Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges

    E-print Network

    Raja, Laxminarayan L.

    Role of trace impurities in large-volume noble gas atmospheric-pressure glow discharges Xiaohui 2002 A computational study of capacitively coupled atmospheric-pressure glow discharges in high atmospheric-pressure glow discharges. © 2002 American Institute of Physics. DOI: 10.1063/1.1497445 Several

  1. Simulation of a direct current microplasma discharge in helium at atmospheric pressure

    E-print Network

    Economou, Demetre J.

    Simulation of a direct current microplasma discharge in helium at atmospheric pressure Qiang Wang at atmospheric pressure was performed based on a one-dimensional fluid model. The microdischarge was found dc atmospheric pressure He microdischarge were presented, as well as successful comparisons

  2. Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure

    E-print Network

    Boyer, Edmond

    at atmospheric pressure A. Sáinz1 , J. Margot2 , M. C. García1 , M. D. Calzada1 1 Grupo de Espectroscopía de+ ) are also expected to play an important role in the discharge kinetics. At atmospheric pressure obeys the Saha-Boltzmann distribution. However, at atmospheric pressure, molecular recombination

  3. Video Article Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by

    E-print Network

    Vertes, Akos

    Video Article Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI.3791/2097 Citation: Nemes P., Vertes A. (2010). Atmospheric-pressure Molecular Imaging of Biological Tissues with an atmospheric-pressure ion source interface is employed to analyze and record the composition of the released

  4. Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its formation mechanism

    E-print Network

    Zexian, Cao

    Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its 2008; accepted 8 June 2009; published online 10 July 2009 Atmospheric pressure plasma jet APPJ can The atmospheric pressure plasma is much advantageous over low pressure plasmas in various aspects. It can be dis

  5. Growth of carbon nanowalls at atmospheric pressure for one-step gas sensor fabrication

    PubMed Central

    2011-01-01

    Carbon nanowalls (CNWs), two-dimensional "graphitic" platelets that are typically oriented vertically on a substrate, can exhibit similar properties as graphene. Growth of CNWs reported to date was exclusively carried out at a low pressure. Here, we report on the synthesis of CNWs at atmosphere pressure using "direct current plasma-enhanced chemical vapor deposition" by taking advantage of the high electric field generated in a pin-plate dc glow discharge. CNWs were grown on silicon, stainless steel, and copper substrates without deliberate introduction of catalysts. The as-grown CNW material was mainly mono- and few-layer graphene having patches of O-containing functional groups. However, Raman and X-ray photoelectron spectroscopies confirmed that most of the oxygen groups could be removed by thermal annealing. A gas-sensing device based on such CNWs was fabricated on metal electrodes through direct growth. The sensor responded to relatively low concentrations of NO2 (g) and NH3 (g), thus suggesting high-quality CNWs that are useful for room temperature gas sensors. PACS: Graphene (81.05.ue), Chemical vapor deposition (81.15.Gh), Gas sensors (07.07.Df), Atmospheric pressure (92.60.hv) PMID:21711721

  6. Comparison of the Structures of Triacylglycerols from Native and Transgenic Medium-Chain Fatty Acid-Enriched Rape Seed Oil by Liquid Chromatography–Atmospheric Pressure Chemical Ionization Ion-Trap Mass Spectrometry (LC–APCI-ITMS)

    Microsoft Academic Search

    Christopher Beermann; Nadine Winterling; Angelika Green; Michael Möbius; Joachim J. Schmitt; Günther Boehm

    2007-01-01

    The sn position of fatty acids in seed oil lipids affects physiological function in pharmaceutical and dietary applications. In\\u000a this study the composition of acyl-chain substituents in the sn positions of glycerol backbones in triacylglycerols (TAG) have been compared. TAG from native and transgenic medium-chain\\u000a fatty acid-enriched rape seed oil were analyzed by reversed-phase high performance liquid chromatography coupled with

  7. Highly sensitive, quick and simple quantification method for mono and disaccharides in aqueous media using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS).

    PubMed

    Ricochon, G; Paris, C; Girardin, M; Muniglia, L

    2011-06-01

    A highly sensitive, rapid LC-APCI-MS method for identification and quantification of mono and disaccharides in simple or complex aqueous phase has been developed. This original method is easy to use, no derivation and no post-column injection are needed. The separation is performed with a hydrophilic amino interaction (HILIC) column allowing high-throughput analysis with analysis times of 15 min for monosaccharides to 22 min for disaccharides. The development of the method carried out with 9 standard saccharides allowed to point out a dynamic range from 0.1-25.6 to 1-256 ?g mL(-1) depending on the considered sugar. Next, the method was validated on saccharides at known concentrations in water and on 2 real samples: orange juice and aqueous phase obtained after enzymatic hydrolysis of sunflower seeds. PMID:21515094

  8. Deposition of vertically oriented carbon nanofibers in atmospheric pressure radio frequency discharge

    SciTech Connect

    Nozaki, Tomohiro; Goto, Tomoya; Okazaki, Ken; Ohnishi, Kuma; Mangolini, Lorenzo; Heberlein, Joachim; Kortshagen, Uwe [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro Tokyo 1528552 (Japan); Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2006-01-15

    Deposition of vertically oriented carbon nanofibers (CNFs) has been studied in an atmospheric pressure radio frequency discharge without dielectric barrier covering the metallic electrodes. When the frequency is sufficiently high so that ions reside in the gap for more than one rf cycle ('trapped ions'), the operating voltage decreases remarkably and the transition from a uniform glow discharge to an arc discharge is suppressed even without dielectric barriers. More importantly, the trapped ions are able to build up a cathodic ion sheath. A large potential drop is created in the sheath between the bulk plasma and the electrode, which is essential for aligning growing CNFs. At the same time, the damage to CNFs due to ion bombardment can be minimized at atmospheric pressure. The primary interest of the present work is in identifying the cathodic ion sheath and investigating how it influences the alignment of growing CNFs in atmospheric pressure plasma-enhanced chemical-vapor deposition. Spectral emission profiles of He (706 nm), H{alpha} (656 nm), and CH (432 nm) clearly showed that a dark space is formed between the cathode layer and the heated bottom electrode. However, increasing the rf power induced the transition to a nonuniform {gamma}-mode discharge which creates intense plasma spots in the dark space. Aligned CNFs can be grown at moderate input power during the initial stage of the deposition process. Catalyst particles were heavily contaminated by precipitated carbon in less than 5 min. Alignment deteriorates as CNFs grow and deposition was virtually terminated by the deactivation of catalyst particles.

  9. Optical and electrical characterization of atmospheric pressure microplasma for CH3OH/H2O/Ar mixtures

    NASA Astrophysics Data System (ADS)

    Cho, Jin Hoon; Park, Young Dong; Choi, Myeong Yeol; Moo Lee, Woong

    2009-10-01

    Atmospheric pressure, non-equilibrium microplasmas have become powerful experimental tools for many applications including microfabrications in microelectronics, surface modifications, environmental processing and many other areas. We investigated that comparative study of atmospheric pressure microdischarge generated in different nonequlibrium discharge with respect to observation optical and electrical characteristics at CH3OH/H2O/Ar mixtures. This paper focuses on plasma chemical reactions from methanol and water vapor mixture and the effects of plasma generation methods in the perspective of hydrogen generation. The microplasmas were generated by resorting to discharge modes such as some variations of glow dielectric barrier discharge (DBD) and also a variation of corona discharge called a microdischarge inside a porous ceramic (MIPC). Plasma chemical reactions were monitored using optical emission spectroscopy to gather information on the degree of non-equilibrium, electron density, uniformity of plasma reaction and concentrations of transient species.

  10. Cold atmospheric pressure air plasma jet for medical applications

    SciTech Connect

    Kolb, J. F.; Price, R. O.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H. [Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23510 (United States); Mohamed, A.-A H. [Department of Physics, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt); Swanson, R. J. [Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23510 (United States); Department of Biological Sciences, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2008-06-16

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2 cm long plasma jet. With increasing flow rate, the flow becomes turbulent and temperatures of the jet are reduced to values close to room temperature. Utilizing the jet, yeast grown on agar can be eradicated with a treatment of only a few seconds. Conversely, animal studies show no skin damage even with exposures ten times longer than needed for pathogen extermination. This cold plasma jet provides an effective mode of treatment for yeast infections of the skin.

  11. Atmospheric pressure cold plasma as an antifungal therapy

    SciTech Connect

    Sun Peng; Wu Haiyan [College of Engineering, Peking University, Beijing 100871 (China); Sun Yi; Liu Wei; Li Ruoyu [Department of Dermatology and Venereology, Peking Univ. 1st Hospital and Research Center for Medical Mycology, Peking Univ., Beijing 100034 (China); Zhu Weidong; Lopez, Jose L. [Department of Applied Science and Technology and Center for Microplasma Science and Technology, Saint Peter's College, Jersey City, New Jersey 07306 (United States); Zhang Jue; Fang Jing [College of Engineering, Peking University, Beijing 100871 (China); Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China)

    2011-01-10

    A microhollow cathode based, direct-current, atmospheric pressure, He/O{sub 2} (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

  12. Atmospheric pressure cold plasma as an antifungal therapy

    NASA Astrophysics Data System (ADS)

    Sun, Peng; Sun, Yi; Wu, Haiyan; Zhu, Weidong; Lopez, Jose L.; Liu, Wei; Zhang, Jue; Li, Ruoyu; Fang, Jing

    2011-01-01

    A microhollow cathode based, direct-current, atmospheric pressure, He/O2 (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

  13. Pluto's Insolation History: Latitudinal Variations and Effects on Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.

    2014-11-01

    Since previous insolation modeling in the early 1990’s, new atmospheric pressure data, increased computational power, and the upcoming flyby of the Pluto system by NASA’s New Horizons spacecraft have generated new motivation and increased capabilities for the study of Pluto’s complex long-term (million-years) insolation history. The two primary topics of interest in studying Pluto’s insolation history are the variations in insolation patterns when integrated over different intervals and the evolution of diurnal insolation patterns over the last several decades. We find latitudinal dichotomies when comparing average insolation over timescales of days, decades, centuries, and millennia. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. For any single rotation of Pluto there is a latitude that receives more insolation relative to the others. Often this is the sub-subsolar latitude but it can also be an arctic circle latitude when near-polar regions of Pluto experience the "midnight sun". We define the amount of that greatest insolation value over the course of one rotation as the "maximum diurnal insolation" (MDI). We find that MDI is driven to its highest values when Pluto’s obliquity creates a long arctic summer (or “midnight sun”) beginning just after perihelion. Pluto’s atmospheric pressure, as measured through stellar occultation observations during the past three decades, appears to correlate with Pluto's currently occurring midnight sun as quantified by the MDI parameter. If insolation (as parameterized by the MDI value) is the single dominant factor driving Pluto's atmospheric pressure, this “Midnight Sun Model” predicts that Pluto's maximum atmospheric pressure will be reached in 2017 followed by a steady decline. Pluto's maximum diurnal insolation value begins dropping after 2017 due to two factors: Pluto’s sub-solar point becomes more equatorial (lessening the midnight sun effect) and the planet continues to recede toward aphelion. This work was supported in part by the NASA New Horizons mission to Pluto under SwRI Subcontract 299433Q.

  14. Electron kinetics in a microdischarge in nitrogen at atmospheric pressure

    SciTech Connect

    Levko, Dmitry [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)] [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France)

    2013-12-14

    Electron kinetics during a microdischarge in nitrogen at atmospheric pressure is studied using the one-dimensional Particle-in-Cell/Monte Carlo Collisions model. It is obtained that the electron energy distribution function can be divided into three parts, namely, the non-equilibrium low-energy part, the Maxwellian function at moderate energies, and the high-energy tail. Simulation results showed that the role of the high-energy tail of electron energy distribution increases, when the distance between electrodes increases.

  15. Driven Motion and Instability of an Atmospheric Pressure Arc

    SciTech Connect

    Max Karasik

    1999-12-01

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental arc furnace is constructed and operated in air with graphite cathode and steel anode at currents 100-250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes.

  16. Electrode erosion in arc discharges at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Hardy, T. L.

    1985-01-01

    An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc discharge at powers less than 1 kW. A free-burning arc configuration and a constricted arc configuration were used to test the materials. Lanthanum hexaboride and thoriated tungsten had low cathode erosion rates while thoriated tungsten and pure tungsten had the lowest anode erosion rates of the materials tested. Anode cooling, reverse gas flow, and external magnetic fields were all found to reduce electrode mass loss.

  17. Electrode erosion in arc discharges at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Hardy, T. L.

    1985-01-01

    An experimental investigation was performed in an effort to measure and increase lifetime of electrodes in an arcjet thruster. The electrode erosion of various anode and cathode materials was measured after tests in an atmospheric pressure nitrogen arc discharge at powers less than 1 kW. A free-burning arc configuration and a constricted arc configuration were used to test the materials. Lanthanum hexboride and thoriated tungsten had low cathode erosion rates while thoriated tungsten and pure tungsten had the lowest anode erosion rates of the materials tested. Anode cooling, reverse gas flow, an external magnetic fields were all found to reduce electrode mass loss.

  18. Microwave generation of stable atmospheric-pressure fireballs in air

    SciTech Connect

    Stephan, Karl D. [Department of Engineering and Technology, Texas State University-San Marcos, San Marcos, Texas 78666 (United States) and Process Energetics Laboratory, Dept. of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78758 (United States)

    2006-11-15

    The generation of stable buoyant fireballs in a microwave cavity in air at atmospheric pressure without the use of vaporized solids is described. These fireballs have some of the characteristics of ball lightning and resemble those reported by Dikhtyar and Jerby [Phys. Rev. Lett. 96, 045002 (2006)], although of a different color, and do not require the presence of molten or vaporized material. Mechanisms of microwave plasma formation and fluid dynamics can account for the observed behavior of the fireballs, which do not appear to meet the accepted definition of dusty plasmas in this case. Relevance to models of ball lightning and industrial applications are discussed.

  19. Cold atmospheric pressure plasma jet interactions with plasmid DNA

    SciTech Connect

    O'Connell, D.; Cox, L. J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Graham, W. G.; Gans, T.; Currell, F. J. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2011-01-24

    The effect of a cold (<40 deg. C) radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. Gel electrophoresis was used to analyze the DNA forms post-treatment. The experimental data are fitted to a rate equation model that allows for quantitative determination of the rates of single and double strand break formation. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks.

  20. Electrical characteristics and formation mechanism of atmospheric pressure plasma jet

    SciTech Connect

    Liu, Lijuan; Zhang, Yu; Tian, Weijing; Meng, Ying; Ouyang, Jiting, E-mail: jtouyang@bit.edu.cn [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

    2014-06-16

    The behavior of atmospheric pressure plasma jet produced by a coplanar dielectric barrier discharge in helium in external electrostatic and magnetic field is investigated. Net negative charges in the plasma jet outside the tube were detected. The deflection of the plume in the external field was observed. The plasma jet is suggested to be formed by the electron beam from the temporal cathode which is accelerated by a longitudinal field induced by the surface charges on the dielectric tube or interface between the helium and ambient air. The helium flow is necessary for the jet formation in the surrounding air.

  1. Twin injection-needle plasmas at atmospheric pressure

    SciTech Connect

    Hong, Yong Cheol; Cho, Soon Chon; Uhm, Han Sup [Department of Molecular Science and Technology, Ajou University, San 5, Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of)

    2007-04-02

    Twin injection-needle plasmas at atmospheric pressure are introduced as low-temperature nonequilibrium plasma source. The plasmas with long plasma columns of about 55 cm are produced from one alternating current (ac) power supply as if each of the plasmas is a fraternal twin and shows different characteristics in plasma column length and gas temperature. The twin plasma columns are regarded as skinny rods with a uniform charge distribution, and the change of the plasma column lengths with different distances between the plasmas is compared with the change of the capacitance of the skinny rods presented as a model.

  2. PENTACHLOROPHENOL IN THE ENVIRONMENT. EVIDENCE FOR ITS ORIGIN FROM COMMERCIAL PENTACHLOROPHENOL BY NEGATIVE CHEMICAL IONIZATION MASS SPECTROMETRY

    EPA Science Inventory

    Commercial pentachlorophenol (PCP) contains significant quantities of tetrachlorophenol (TCP). The occurrence of TCP in environmental samples provides a chemical marker for PCP originating from commercial formulations. Negative chemical ionization mass spectrometry has been used ...

  3. PENTACHLOROPHENOL IN THE ENVIRONMENT: EVIDENCE FOR ITS ORIGIN FROM COMMERCIAL PENTACHLOROPHENOL BY NEGATIVE CHEMICAL IONIZATION MASS SPECTROMETRY

    EPA Science Inventory

    Commercial pentachlorophenol (PCP) contains significant quantities of tetrachlorophenol (TCP). The occurrence of TCP in environmental samples provides a chemical marker for PCP originating from commercial formulations. Negative chemical ionization mass spectrometry has been used ...

  4. Plasma-assisted reaction chemical ionization for elemental mass spectrometry of organohalogens.

    PubMed

    Wang, Haopeng; Lin, Ninghang; Kahen, Kaveh; Badiei, Hamid; Jorabchi, Kaveh

    2014-04-01

    We present plasma-assisted reaction chemical ionization (PARCI) for elemental analysis of halogens in organic compounds. Organohalogens are broken down to simple halogen-containing molecules (e.g., HBr) in a helium microwave-induced plasma followed by negative mode chemical ionization (CI) in the afterglow region. The reagent ions for CI originate from penning ionization of gases (e.g., N2) introduced into the afterglow region. The performance of PARCI-mass spectrometry (MS) is evaluated using flow injection analyses of organobromines, demonstrating 5-8 times better sensitivities compared with inductively coupled plasma MS. We show that compound-dependent sensitivities in PARCI-MS mainly arise from sample introduction biases. PMID:24474553

  5. Influence of gas flow dynamics on discharge stability and on the uniformity of atmospheric pressure PECVD thin film

    Microsoft Academic Search

    H. Caquineau; I. Enache; N. Gherardi; N. Naudé; F. Massines

    2009-01-01

    The aim of this paper is to improve the understanding of the mechanisms controlling the uniformity of thin films made by atmospheric pressure plasma enhanced chemical vapour deposition (AP-PECVD). To reach this goal, the influence of the gas flow-rate and injection design on the thin film thickness uniformity is studied through experiments and numerical simulation in the case of silica-like

  6. ELECTRON AFFINITIES OF POLYNUCLEAR AROMATIC HYDROCARBONS AND NEGATIVE ION CHEMICAL IONIZATION SENSITIVITIES

    EPA Science Inventory

    Negative-ion chemical-ionization mass spectrometry (NICI MS) has the potential to be a very useful technique in identifying various polycyclic aromatic hydrocarbons (PAHs) in soil and sediment samples. Some PAHs give much stronger signals under NICI MS conditions than others. On ...

  7. Inactivation of Escherichia coli using atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kuwahata, Hiroshi; Yamaguchi, Takeshi; Ohyama, Ryu-ichiro; Ito, Atsushi

    2015-01-01

    An atmospheric-pressure argon (Ar) plasma jet was applied to the inactivation of Escherichia coli. The Ar plasma jet was generated at a frequency of 10 kHz, an applied voltage of 10 kV, and an Ar gas flow rate of 10 L/min at atmospheric pressure. E. coli cells seeded on an agar medium in a Petri dish were inactivated by Ar plasma jet irradiation for 1 s. Scanning electron microscopy (SEM) revealed that E. coli cells were killed because their cell wall and membrane were disrupted. To determine the causes of the disruption of the cell wall and membrane of E. coli, we performed the following experiments: the measurement of the surface temperature of an agar medium using a thermograph, the analysis of an emission spectrum of a plasma jet obtained using a multichannel spectrometer, and the determination of the distribution of the concentration of hydrogen peroxide (H2O2) generated on an agar medium by plasma jet irradiation using semiquantitative test strips. Moreover, H2O2 solutions of different concentrations were dropped onto an agar medium seeded with E. coli cells to examine the contribution of H2O2 to the death of E. coli. The results of these experiments showed that the cell wall and membrane of E. coli were disrupted by electrons in the plasma jet, as well as by electroneutral excited nitrogen molecules (N2) and hydroxyl (OH) radicals in the periphery of the plasma jet.

  8. Pluto's insolation history: Latitudinal variations and effects on atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Earle, Alissa M.; Binzel, Richard P.

    2015-04-01

    Since previous long-term insolation modeling in the early 1990s, new atmospheric pressure data, increased computational power, and the upcoming flyby of the Pluto system by NASA's New Horizons spacecraft have generated new motivation and increased capabilities for the study of Pluto's complex long-term (million-years) insolation history. The two primary topics of interest in studying Pluto's insolation history are the variations in insolation patterns when integrated over different intervals and the evolution of diurnal insolation patterns over the last several decades. We find latitudinal dichotomies when comparing average insolation over timescales of days, decades, centuries, and millennia, where all timescales we consider are short relative to the predicted timescales for Pluto's chaotic orbit. Depending on the timescales of volatile migration, some consequences of these insolation patterns may be manifested in the surface features revealed by New Horizons. We find the Maximum Diurnal Insolation (MDI) at any latitude is driven most strongly when Pluto's obliquity creates a long arctic summer (or "midnight sun") beginning just after perihelion. Pluto's atmospheric pressure, as measured through stellar occultation observations during the past three decades, shows a circumstantial correlation with this midnight sun scenario as quantified by the MDI parameter.

  9. [Vibrational temperature of plasma plume in atmospheric pressure air].

    PubMed

    Li, Xue-Chen; Chang, Yuan-Yuan; Jia, Peng-Ying; Zhao, Huan-Huan; Bao, Wen-Ting

    2013-07-01

    A tri-electrode discharge device was designed in a dielectric barrier discharge configurations to generate a fairly large volume plasma plume in atmospheric pressure air. The discharge characteristics of the plasma plume were investigated by an optical method. The discharge emission from the plasma plume was collected by a photomultiplier tube. It was found that the number of discharge pulse per cycle of the applied voltage increased with increasing the peak value of the applied voltage. The emission spectra of the plasma plume were collected by a spectrometer. The vibrational temperature was calculated by fitting the experimental data to the theoretical one. Results showed that the vibrational temperature of the plasma plume decreases with increasing the U(p). Spatially resolved measurement of the vibrational temperature was also conducted on the plasma plume with the same method. Results showed that the vibrational temperature increases firstly and then decreases with increasing distance from the nozzle. The vibrational temperature reachs its maximum when the distance is 5.4 mm from the nozzle. These experimental phenomena were analyzed qualitatively based on the discharge theory. These results have important significance for the industrial applications of the plasma plume in atmospheric pressure air. PMID:24059168

  10. Surface modification of cellulosic substrates via atmospheric pressure plasma polymerization of acrylic acid: Structure and properties

    NASA Astrophysics Data System (ADS)

    Garcia-Torres, Jose; Sylla, Dioulde; Molina, Laura; Crespo, Eulalia; Mota, Jordi; Bautista, Llorenç

    2014-06-01

    Surface chemical modification of cellulose-based substrates has been carried out by atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) of acrylic acid. The structure/properties relationship of the samples was studied as a function of the plasma experimental conditions. Acrylic acid monomer/helium ratio and treatment speed clearly influences the wettability properties of the paper substrate: advancing contact angle values were reduced to the half if compare to non-treated paper. Surface morphology of the films did not greatly vary at short polymerization times but fibers were covered by a poly(acrylic acid) film at longer times. FTIR and XPS techniques allowed detecting the retention of carboxylic acid groups/moieties. The possibility to quickly design architectures with tunable carboxylic functions by modifying the plasma processing parameters is shown.

  11. Development of antimicrobial coatings by atmospheric pressure plasma using a guanidine-based precursor.

    PubMed

    Yim, Jacqueline H; Fleischman, Michelle S; Rodriguez-Santiago, Victor; Piehler, Lars T; Williams, André A; Leadore, Julia L; Pappas, Daphne D

    2013-11-27

    Antimicrobial coatings deposited onto ultra high molecular weight polyethylene (UHMWPE) films were investigated using an atmospheric pressure - plasma enhanced chemical vapor deposition (AP-PECVD) process. Varying concentrations of a guanidine-based liquid precursor, 1,1,3,3-tetramethylguanidine, were used, and different deposition conditions were studied. Attenuated total reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) were used to study the chemical structure and elemental composition of the coatings. Conformity, morphology, and coating thickness were assessed through SEM and AFM. Optimal AP-PECVD parameters were chosen and applied to deposit guanidine coatings onto woven fabrics. The coatings exhibited high antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) based on a modified-AATCC 100 test standard, where 2-5 log reductions were achieved. PMID:24164174

  12. Treatment of polycarbonate by dielectric barrier discharge (DBD) at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kostov, K. G.; Hamia, Y. A. A.; Mota, R. P.; dos Santos, A. L. R.; Nascente, P. A. P.

    2014-05-01

    Generally most plastic materials are intrinsically hydrophobic, low surface energy materials, and thus do not adhere well to other substances. Surface treatment of polymers by discharge plasmas is of great and increasing industrial application because it can uniformly modify the surface of sample without changing the material bulk properties and is environmentally friendly. The plasma processes that can be conducted under ambient pressure and temperature conditions have attracted special attention because of their easy implementation in industrial processing. Present work deals with surface modification of polycarbonate (PC) by a dielectric barrier discharge (DBD) at atmospheric pressure. The treatment was performed in a parallel plate reactor driven by a 60Hz power supply. The DBD plasmas at atmospheric pressure were generated in air and nitrogen. Material characterization was carried out by contact angle measurements, and X-ray photoelectron spectroscopy (XPS). The surface energy of the polymer surface was calculated from contact angle data by Owens-Wendt method using distilled water and diiodomethane as test liquids. The plasma-induced chemical modifications are associated with incorporation of polar oxygen and nitrogen containing groups on the polymer surface. Due to these surface modifications the DBD-treated polymers become more hydrophilic. Aging behavior of the treated samples revealed that the polymer surfaces were prone to hydrophobic recovery although they did not completely recover their original wetting properties.

  13. Superhydrophobic treatment using atmospheric-pressure He/C4F8 plasma for buoyancy improvement

    NASA Astrophysics Data System (ADS)

    Noh, Sooryun; Moon, A.-Young; Moon, Se Youn

    2015-04-01

    A superhydrophobic miniature boat was fabricated with aluminum alloy plates treated with atmospheric-pressure helium (He)/octafluorocyclobutane (C4F8) plasma using 13.56 MHz rf power. When only 0.13% C4F8 was added to He gas, the contact angle of the surface increased to 140° and the surface showed superhydrophobic properties. On the basis of chemical and morphological analyses, fluorinated functional groups (CF, CF2, and CF3) and nano-/micro-sized particles were detected on the Al surface. These features brought about superhydrophobicity similar to the lotus effect. While the miniature boat, assembled with plasma-treated plates, was immersed in water, a layer of air (i.e., a plastron) surrounded the superhydrophobic surfaces. This effect contributed to the development of a 4.7% increase in buoyancy. In addition, the superhydrophobic properties lasted for two months under the submerged condition. These results demonstrate that treatment with atmospheric-pressure He/C4F8 plasma is a promising method of improving the load capacity and antifouling properties, and reducing the friction of marine ships through a fast and low-cost superhydrophobic treatment process.

  14. Oxidation of volatile organic compounds by microwave plasma at atmospheric pressure

    SciTech Connect

    Lee, D.J. [Aneptek Corp., Natick, MA (United States); Ruden, T.E.

    1997-12-31

    The theory of microwave excited, non-thermal plasma destruction of VOCs at atmospheric pressure is described in US Navy Patents 5,468,356 and 5,478,532. Advantages of the microwave approach as compared to DC or AC corona discharge, AC barrier dielectric discharge, and DC glow pulsed discharge have been discussed. Destruction efficiency of 96% for toluene (C{sub 7}H{sub 8}) in air was obtained by the Navy using a TM{sub 010} cavity. Power was 6 kW with 600 W coupled to the plasma. Aneptek Corporation, under a license with the US Navy, has continued this research. Improvements have been made in the cavity arc stability, Q, and coupling iris. Stable operation of the plasma has been achieved at atmospheric pressure at a power of 1 kW and improved coupling of about 70%. Measured flow rates are up to 10 liter/minute with an upper limit not yet established. Tests on the destruction of isobutylene (C{sub 4}H{sub 8}) are in progress. Oxidation via the metastable oxygen molecule results in the production of CO{sub 2} and water. The authors observe a high level of CO{sub 2} generation consistent with the stoichiometric relationship; CO and NO{sub x} are not generated. Monochromator analysis shows that ionization of nitrogen does not occur. In addition, they observe minimal bulk heating of the air. This is consistent with the theory prediction that the electron energy is well below that necessary to excite nitrogen molecules in the air. They report on VOC destruction efficiency, results of various diagnostic tests, and new cavity design concepts.

  15. Fragmentation of allylmethylsulfide by chemical ionization: dependence on humidity and inhibiting role of water.

    PubMed

    Maihom, Thana; Schuhfried, Erna; Probst, Michael; Limtrakul, Jumras; Märk, Tilmann D; Biasioli, Franco

    2013-06-20

    We report on a previously unknown reaction mechanism involving water in the fragmentation reaction following chemical ionization. This result stems from a study presented here on the humidity-dependent and energy-dependent endoergic fragmentation of allyl methyl sulfide (AMS) upon protonation in a proton transfer reaction-mass spectrometer (PTR-MS). The fragmentation pathways were studied with experimental (PTR-MS) and quantum chemical methods (polarizable continuum model (PCM), microhydration, studied at the MP2/6-311+G(3df,2p)//MP2/6-31G(d,p) level of theory). We report in detail on the energy profiles, reaction mechanisms, and proton affinities (G4MP2 calculations). In the discovered reaction mechanism, water reduces the fragmentation of protonated species in chemical ionization. It does so by direct interaction with the protonated species via covalent binding (C3H5(+)) or via association (AMS·H(+)). This stabilizes intermediate complexes and thus overall increases the activation energy for fragmentation. Water thereby acts as a reusable inhibitor (anticatalyst) in chemical ionization. Moreover, according to the quantum chemical (QC) results, when water is present in abundance it has the opposite effect and enhances fragmentation. The underlying reason is a concentration-dependent change in the reaction principle from active inhibition of fragmentation to solvation, which then enhances fragmentation. This amphoteric behavior of water is found for the fragmentation of C3H5(+) to C3H3(+), and similarly for the fragmentation of AMS·H(+) to C3H5(+). The results support humidity-dependent quantification efforts for PTR-MS and chemical ionization mass spectrometry (CIMS). Moreover, the results should allow for a better understanding of ion-chemistry in the presence of water. PMID:23682687

  16. Influence of ionization on the Gupta and on the Park chemical models

    NASA Astrophysics Data System (ADS)

    Morsa, Luigi; Zuppardi, Gennaro

    2014-12-01

    This study is an extension of former works by the present authors, in which the influence of the chemical models by Gupta and by Park was evaluated on thermo-fluid-dynamic parameters in the flow field, including transport coefficients, related characteristic numbers and heat flux on two current capsules (EXPERT and Orion) during the high altitude re-entry path. The results verified that the models, even computing different air compositions in the flow field, compute only slight different compositions on the capsule surface, therefore the difference in the heat flux is not very relevant. In the above mentioned studies, ionization was neglected because the velocities of the capsules (about 5000 m/s for EXPERT and about 7600 m/s for Orion) were not high enough to activate meaningful ionization. The aim of the present work is to evaluate the incidence of ionization, linked to the chemical models by Gupta and by Park, on both heat flux and thermo fluid-dynamic parameters. The present computer tests were carried out by a direct simulation Monte Carlo code (DS2V) in the velocity interval 7600-12000 m/s, considering only the Orion capsule at an altitude of 85 km. The results verified what already found namely when ionization is not considered, the chemical models compute only a slight different gas composition in the core of the shock wave and practically the same composition on the surface therefore the same heat flux. On the opposite, the results verified that when ionization is considered, the chemical models compute different compositions in the whole shock layer and on the surface therefore different heat flux. The analysis of the results relies on a qualitative and a quantitative evaluation of the effects of ionization on both chemical models. The main result of the study is that when ionization is taken into account, the Park model is more reactive than the Gupta model; consequently, the heat flux computed by Park is lower than the one computed by Gupta; using the Gupta model, in the design of a thermal protection system, is recommended.

  17. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    SciTech Connect

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)] [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2013-02-15

    Results are presented from experimental studies of decomposition of toluene (C{sub 6}H{sub 5}CH{sub 3}) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C{sub 6}H{sub 5}CH{sub 3} removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N{sub 2}: O{sub 2}: H{sub 2}O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C{sub 6}H{sub 5}CH{sub 3} decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C{sub 6}H{sub 5}CH{sub 3} is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  18. Plasma formation in atmospheric pressure helium discharges under different background air pressures

    SciTech Connect

    Liu Yaoge; Hao Yanpeng; Zheng Bin [School of Electric Power, South China University of Technology, Guangzhou 510640 (China)

    2012-09-15

    Atmospheric pressure glow discharges generated between parallel-plate electrodes in helium have been characterized using temporally resolved emission spectra. The variation of typical spectral lines over time has been analyzed. In helium with a low concentration of N{sub 2}, the emission of He at 706.5 nm is dominant and appears 500 ns earlier than N{sub 2}{sup +} first negative bands, indicating low reaction rates of Penning ionization and charge transfer in the initial stage. During the decay, it is the Penning ionization caused by He metastables with a long lifetime rather than the charge transfer reaction that leads to the long decay of N{sub 2}{sup +} emissions. When helium contains a higher concentration of N{sub 2} molecules, the N{sub 2}{sup +} first negative bands become the most intense, and emissions from He, N{sub 2}{sup +}, and O exhibit similar behavior as they increase. The emissions last for a shorter time under such conditions because of rapid consumption of He metastables and He{sub 2}{sup +}.

  19. Investigation of deprotonation reactions on globular and denatured proteins at atmospheric pressure by ESSI-MS.

    PubMed

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

    2008-04-01

    Deprotonation reactions of multiply charged protein ions have been studied by introducing volatile reference bases at atmospheric pressure between an electrosonic spray ionization (ESSI) source and the inlet of a mass spectrometer. Apparent gas-phase basicities (GB(app)) of different charge states of protein ions were determined by a bracketing approach. The results obtained depend on the conformation of the protein ions in the gas phase, which is linked to the type of buffer used (denaturing or nondenaturing). In nondenaturing buffer, the GB(app) values are consistent with values predicted by the group of Kebarle using an electrostatic model (J. Mass Spectrom.2002, 38, 618) based on the crystal structures, but taking into account salt bridges between ionized basic and acidic sites on the protein surface. A new basicity order for the most basic sites was therefore obtained. An excellent agreement with the charge residue model (CRM) is obtained when comparing the observed and calculated maximum charge state. Decharging of the proteins in the electrosonic spray process could be also useful in the study on noncovalent complexes, by decreasing repulsive electrostatic interactions. A unified mechanism of the ESSI process is proposed. PMID:18276154

  20. Controlled Microdroplet Transport in an Atmospheric Pressure Microplasma

    E-print Network

    Maguire, P D; Kelsey, C P; Bingham, A; Montgomery, E P; Bennet, E D; Potts, H E; Rutherford, D; McDowell, D A; Diver, D A; Mariotti, D

    2015-01-01

    We report the controlled injection of near-isolated micron-sized liquid droplets into a low temperature He-Ne steady-state rf plasma at atmospheric pressure. The H2O droplet stream is constrained within a 2 mm diameter quartz tube. Imaging at the tube exit indicates a log-normal droplet size distribution with an initial count mean diameter of 15 micrometers falling to 13 micrometers with plasma exposure. The radial velocity profile is approximately parabolic indicating near laminar flow conditions with the majority of droplets travelling at >75% of the local gas speed and having a plasma transit time of microreactors and remote delivery of active species for pla...

  1. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  2. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Gary S. Selwyn

    2001-01-09

    Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

  3. Development of ac corona discharge modes at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    El-Koramy, Reda Ahmed; Yehia, Ashraf; Omer, Mohamed

    2011-02-01

    Corona discharges in gases exist under several distinctive forms. In this paper, a survey study has been made of ac corona discharge modes generated in some different gases fed in a wire-duct reactor with a constant rate of flowing at atmospheric pressure. The properties of different corona modes are analyzed under some condition transitions from Trichel pulses to a steady glow. In the course of the presented experimental work, numerous apparent contradictions with earlier observations necessitated further study and are given to provide more information on the physical mechanisms of the ac corona discharges. Furthermore, we have gained insight into some new technologies and applications of the environmentally friendly corona and plasma discharges.

  4. Efficacy of Nonthermal Atmospheric Pressure Plasma for Tooth Bleaching

    PubMed Central

    Nam, Seoul Hee; Lee, Hae June; Hong, Jin Woo; Kim, Gyoo Cheon

    2015-01-01

    The conventional light source used for tooth bleaching has the potential to cause thermal damage, and the actual role of the light source is doubtful. In this study, we evaluated bleaching efficacy, temperature, and morphological safety after tooth bleaching with nonthermal atmospheric pressure plasma. Tooth bleaching combined with plasma had improved efficacy in providing a higher level of brightness. The temperature of the pulp chamber was maintained around 37°C, indicating that the plasma does not cause any thermal damage. The morphological results of tooth bleaching with plasma did not affect mineral composition under scanning electron microscopy (SEM) observations. On the basis of these results, the application of plasma and low concentration of 15% carbamide peroxide (CP) has a high capability for effective tooth bleaching. It can be documented that plasma is a safe energe source, which has no deleterious effects on the tooth surface. PMID:25685843

  5. Generation of reactive species by an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    The role of gas mixing in reactive species delivery to treatment surfaces for an atmospheric pressure capacitively coupled plasma helium jet is investigated by numerical modelling. Atomic oxygen in the jet effluent is shown to quickly convert to ozone for increasing device to surface separation due to the molecular oxygen present in the gas mixture. Surface profiles of reactive oxygen species show narrow peaks for atomic oxygen and broader surface distributions for ozone and metastable species. Production efficiency of atomic oxygen to the helium plasma jet by molecular oxygen admixture is shown to be dependent on electro-negativity. Excessive molecular oxygen admixture results in negative ion dominance over electrons which eventually quenches the plasma. Interaction of the plasma jet with an aqueous surface showed hydrogen peroxide as the dominant species at this interface. Gas heating by the plasma is found to be dominated by elastic electron collisions and positive ion heating. Comparison with experimental measurements for atomic oxygen shows good agreement.

  6. Atmospheric pressure plasma surface modification of carbon fibres

    NASA Astrophysics Data System (ADS)

    Kusano, Y.; Andersen, T. L.; Michelsen, P. K.

    2008-03-01

    Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He/O2 and Ar plasma treatments, mainly attributed to an increase in the density of the C-O single bond at the carbon fibre surfaces. The O/C ratio increased to 0.182 after 1-s He plasma treatment, and remained approximately constant after longer treatment. After exposure in an ambient air at room temperature for a month the O/C ratio at the plasma treated surfaces decreased to 0.151, which is close to that of the untreated ones. It can be attributed to the adsorption of hydrocarbon contamination at the plasma treated surfaces.

  7. Time and space variability of spectral estimates of atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Canavero, Flavio G.; Einaudi, Franco

    1987-01-01

    The temporal and spatial behaviors of atmospheric pressure spectra over the northern Italy and the Alpine massif were analyzed using data on surface pressure measurements carried out at two microbarograph stations in the Po Valley, one 50 km south of the Alps, the other in the foothills of the Dolomites. The first 15 days of the study overlapped with the Alpex Intensive Observation Period. The pressure records were found to be intrinsically nonstationary and were found to display substantial time variability, implying that the statistical moments depend on time. The shape and the energy content of spectra depended on different time segments. In addition, important differences existed between spectra obtained at the two stations, indicating a substantial effect of topography, particularly for periods less than 40 min.

  8. Decomposition of Glycerine by Water Plasmas at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Takayuki, Watanabe; Narengerile

    2013-04-01

    High concentration of aqueous glycerine was decomposed using a direct current (DC) plasma torch at atmospheric pressure. The torch can generate the plasma with water as the plasma-supporting gas in the absence of any additional gas supply system and cooling devices. The results indicated that 5 mol% glycerine was completely decomposed by water plasmas at arc powers of 0.55~1.05 kW. The major products in the effluent gas were H2 (68.9%~71.1%), CO2 (18.9%~23.0%), and CO (0.2%~0.6%). However, trace levels of formic acid (HCOOH) and formaldehyde (HCHO) were observed in the liquid effluent. The results indicated that the water plasma waste treatment process is capable of being an alternative green technology for organic waste decomposition.

  9. Efficacy of nonthermal atmospheric pressure plasma for tooth bleaching.

    PubMed

    Nam, Seoul Hee; Lee, Hae June; Hong, Jin Woo; Kim, Gyoo Cheon

    2015-01-01

    The conventional light source used for tooth bleaching has the potential to cause thermal damage, and the actual role of the light source is doubtful. In this study, we evaluated bleaching efficacy, temperature, and morphological safety after tooth bleaching with nonthermal atmospheric pressure plasma. Tooth bleaching combined with plasma had improved efficacy in providing a higher level of brightness. The temperature of the pulp chamber was maintained around 37°C, indicating that the plasma does not cause any thermal damage. The morphological results of tooth bleaching with plasma did not affect mineral composition under scanning electron microscopy (SEM) observations. On the basis of these results, the application of plasma and low concentration of 15% carbamide peroxide (CP) has a high capability for effective tooth bleaching. It can be documented that plasma is a safe energy source, which has no deleterious effects on the tooth surface. PMID:25685843

  10. Next generation of the atmospheric pressure loading service

    NASA Astrophysics Data System (ADS)

    Petrov, Leonid; Boy, Jean-Paul

    2013-04-01

    A major revision of the service of the atmospheric pressure loading launched in 2002 is scheduled to be completed in 2013. Revised service accessible at http://astrogeo.org/loading will have improved accuracy, reduced latency, and better user interface. Improvement in accuracy will be achieved owing to using numerical models with much higher resolution (several tens of kilometers versus several hundreds of kilometers) owing to more precise surface pressure reduction, and owing to taking into account the dynamic response of the ocean. Using operational numerical weather models matched to reanalysis model allows us to compute loading with latencies measured by hours. Using advanced algorithms for loading computation running at high performance computer allows to offer a service of computing loading on the fly.

  11. Phenomena of oscillations in atmospheric pressure direct current glow discharges

    SciTech Connect

    Liu, Fu-cheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)] [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yan, Wen; Wang, De-zhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-12-15

    Self-sustained oscillations in a dc glow discharge with a semiconductor layer at atmospheric pressure were investigated by means of a one-dimensional fluid model. It is found that the dc glow discharge initially becomes unstable in the subnormal glow region and gives rise to oscillations of plasma parameters. A variety of oscillations with one or more frequencies have been observed under different conditions. The discharge oscillates between the glow discharge mode and the Townsend discharge mode in the oscillations with large amplitude while operates in the subnormal glow discharge mode all the while in the oscillations with small amplitude. Fourier Transform spectra of oscillations reveal the transition mechanism between different oscillations. The effects of semiconductor conductivity on the oscillation frequency of the dominant mode, gas voltage, as well as the discharge current have also been analyzed.

  12. Plasmid DNA damage induced by helium atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

    2014-03-01

    A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

  13. Characterization and stabilization of atmospheric pressure DC microplasmas and their application to thin film deposition

    NASA Astrophysics Data System (ADS)

    Staack, David Alexander

    A comprehensive study was carried out to examine the feasibility of depositing thin films using atmospheric pressure DC and RF microplasma discharges. Atmospheric pressure plasmas for material processing are desirable because of the lower costs, higher throughput, continuous processing, and potentially novel applications obtainable by not using vacuum systems. However, several major concerns exist because of the higher pressures. These are related to: (1) discharge stability, (2) non-thermal operation, (3) non-uniformities, and (4) particle formation. These concerns were investigated using DC and RF microplasmas for atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) of thin films. The DC discharges were fundamentally characterized in Air, helium, nitrogen, argon, hydrogen, methane and mixtures thereof by: (1) voltage-current measurements, (2) current density measurements, (3) microscopic visualization and manipulation of the discharges, and (4) extensive spectroscopic measurements. Measurements were made for breakdown, transitional and stable regimes in current ranges from 0 mA to 40 mA, and discharge gaps sizes from 20 mum to 10 mm. The main focus of the optical emission spectroscopy (OES) was the measurements of rotational and vibrational temperature measurement made by the fitting of experimental data to spectral models of the N2 2nd positive system (N2 C3piu?B3pi g), though the N+2 1st negative system, the NO beta, gamma, delta, and epsilon systems, and the atomic emissions lines were also used for additional temperature measurements, species identification, and measurements of relative concentrations. The structure, electric field, current density and voltage-current measurements indicated that the DC microplasmas operate as density scaled version of the low-pressure normal glow discharge regime with notable exceptions. Spectroscopic measurements show the gas temperatures to vary from ambient to 2000K depending on conditions and to be non-equilibrium discharges, T gas atmospheric pressure RF capacitively coupled plasmas (CCP) utilizing helium buffering for stabilization were also investigated for AP-PECVD. Characterization revealed that the high concentrations of helium were required to maintain low current densities and prevent alpha to gamma mode transition and instabilities. Comparisons were made between the DC, and RF atmospheric pressure deposition system and results from the literature. Properties in general are similar to those achieved by other techniques with the structure of the amorphous carbon films ranging from more polymeric-like-carbon to more diamond-like-carbon. In comparison to the RF deposition, the DC system could deposit more durable films, likely due to higher power densities and ion energies, but the discharge was more sensitive to the substrate properties. The DC microplasma system could also deposit thin films with significantly less helium buffering as helium was not necessary for stabilization.

  14. Static Water Contact Angle Analysis of Cyclonic Atmospheric Pressure Plasma-Activated Polycarbonate

    NASA Astrophysics Data System (ADS)

    Huang, Chun; Wu, Shin-Yi; Liu, Yu-Chia; Chang, Ya-Chi; Tsai, Ching-Yuan

    2011-01-01

    Polycarbonate (PC) films were activated using cyclonic atmospheric pressure plasma. The experimentally measured gas phase temperature was from 30 to 95 °C, demonstrating that this cyclonic atmospheric pressure plasma can treat heat-sensitive polymeric materials at the low temperatures. The surface hydrophilicity changes of cyclonic atmospheric pressure plasma-treated PC films were determined by water contact angle analysis. The activation effects of plasma operational parameters including treatment time, plasma power, and distance of nozzle to substrate on the PC surface features were investigated. The glow feature and luminous plasma species in the cyclonic atmospheric pressure plasma were identified by optical emission spectroscopy (OES). Cyclonic atmospheric pressure plasma-activated PC films showed a significant decrease in water contact angle. In this investigation, we developed an innovative technique for chamberless polymeric surface activation by this atmospheric pressure plasma processing.

  15. Cluster chemical ionization and deuterium exchange mass spectrometry in supersonic molecular Beams.

    PubMed

    Dagan, S; Amirav, A

    1996-06-01

    A cluster-based chemical ionization method has been developed that produces protonated molecular ions from molecules introduced through a supersonic molecular beam interface. Mixed clusters of the analyte and a clustering agent (water or methanol) are produced in the expansion region of the beam, and are subsequently ionized by "fly through" electron impact (EI) ionization, which results in a mass spectrum that is a combination of protonated molecular ion peaks together with the conventional EI fragmentation pattern. The technique is presented and discussed as a tool complementary to electron impact ionization in supersonic molecular beams. Surface-induced dissociation on a rhenium oxide surface is also applied to simplify the mass spectra of clusters and reveal the analyte spectrum. The high gas flow rates involved with the supersonic molecular beam interface that enable the easy introduction of the clustering agents also have been used to introduce deuterating agents. An easy-to-use, fast, and routine on-line deuterium exchange method was developed to exchange active hydrogens (NH, OH). This method, combined with electron impact ionization, is demonstrated and discussed in terms of the unique information available through the EI fragmentation patterns, its ability to help in isomer identification, and possible applications with fast gas chromatography-mass spectrometry in supersonic molecular beams. PMID:24203427

  16. Development and evaluation of a nano-electrospray ionisation source for atmospheric pressure ion mobility spectrometry.

    PubMed

    Bramwell, Claire J; Colgrave, Michelle L; Creaser, Colin S; Dennis, Richard

    2002-11-01

    A nano-electrospray ionisation source has been designed and constructed for a high temperature ion mobility spectrometer. The drift cell was modified by replacement of the 63Ni atmospheric pressure chemical ionisation source with a tube lens/desolvation region and operated using commercial nano-electrospray capillaries. Ions were introduced into the drift region via a Bradbury-Nielson gate (pulse width 50 micros, repetition period 20 ms). A unidirectional flow of nitrogen was used as the drift gas at temperatures in the range 100-150 degrees C to aid desolvation. The performance of the nano-electrospray ion source has been demonstrated for analytes including crown ethers, amino acids and peptides. Reduced mobilities determined by nano-ESI were consistent with those reported using a 63Ni ion source. PMID:12475036

  17. Chemical ionization tandem mass spectrometer for the in situ measurement of methyl hydrogen peroxide

    SciTech Connect

    St Clair, Jason M.; McCabe, David C. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Crounse, John D. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States); Steiner, Urs [Varian, Inc., Santa Clara, California 95051 (United States); Wennberg, Paul O. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125 (United States); Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125 (United States)

    2010-09-15

    A new approach for measuring gas-phase methyl hydrogen peroxide [(MHP) CH{sub 3}OOH] utilizing chemical ionization mass spectrometry is presented. Tandem mass spectrometry is used to avoid mass interferences that hindered previous attempts to measure atmospheric CH{sub 3}OOH with CF{sub 3}O{sup -} clustering chemistry. CH{sub 3}OOH has been successfully measured in situ using this technique during both airborne and ground-based campaigns. The accuracy and precision for the MHP measurement are a function of water vapor mixing ratio. Typical precision at 500 pptv MHP and 100 ppmv H{sub 2}O is {+-}80 pptv (2 sigma) for a 1 s integration period. The accuracy at 100 ppmv H{sub 2}O is estimated to be better than {+-}40%. Chemical ionization tandem mass spectrometry shows considerable promise for the determination of in situ atmospheric trace gas mixing ratios where isobaric compounds or mass interferences impede accurate measurements.

  18. Bimolecular and unimolecular contributions to the disparate self-chemical ionizations of ? Pinene and camphene isomers

    Microsoft Academic Search

    Touradj Solouki; Jan E. Szulejko

    2007-01-01

    The contributions of molecular and fragment ions toward the disparate self-chemical ionization (SCI) of ?-pinene and camphene isomers were investigated. A kinetic model was constructed to predict the SCI outcomes for these two\\u000a C10H16 isomers. A major portion of the camphene molecular ions (isolated 500 ms after the 10 ms EI event at 24 eV) unimolecularly\\u000a dissociated within 200 s

  19. Real-time monitoring of volatile organic compounds using chemical ionization mass spectrometry

    DOEpatents

    Mowry, Curtis Dale (Albuquerque, NM); Thornberg, Steven Michael (Peralta, NM)

    1999-01-01

    A system for on-line quantitative monitoring of volatile organic compounds (VOCs) includes pressure reduction means for carrying a gaseous sample from a first location to a measuring input location maintained at a low pressure, the system utilizing active feedback to keep both the vapor flow and pressure to a chemical ionization mode mass spectrometer constant. A multiple input manifold for VOC and gas distribution permits a combination of calibration gases or samples to be applied to the spectrometer.

  20. Electron impact and chemical ionization mass spectral analysis of a volatile uranyl derivative

    SciTech Connect

    Reutter, D.J.; Hardy, D.R.

    1981-01-01

    Quadrupole mass spectral analysis of the volatile uranium ligand complex bis (1,1,1,5,5,5-hexafluoro-2,4-pentanedionato) dioxouranium-di-n-butyl sulfoxide is described utilizing electron impact (EI) and methane chemical ionization (CI) ion sources. All major ions are tentatively identified and the potential usefulness of this complex for determining uranium isotope /sup 235/U//sup 238/U abundance is demonstrated.

  1. Hair analysis for nordiazepam and oxazepam by gas chromatography-negative-ion chemical ionization mass spectrometry

    Microsoft Academic Search

    Pascal Kintz; Vincent Cirimele; François Vayssette; Patrice Mangin

    1996-01-01

    A procedure is presented for the identification of nordiazepam and its metabolite, oxazepam, in human hair. The method involves decontamination of hair with dichloromethane, incubation in phosphate buffer (pH 7.6) in the presence of deuterated internal standards, liquid-liquid extraction, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide plus 1% trimethylchlorosilane and gas chromatography-mass spectrometry using negative-ion chemical ionization with methane. Among thirty samples obtained from

  2. Chemical Ionization Mass Spectrometer (CIMS) Shanhu Lee, Kent State University (http://www.personal.kent.edu/~slee19/)

    E-print Network

    Lee, Shan-Hu

    . Kosciuch, Proton transfer mass spectrometry at high drift tube pressure, Int. J. Mass. Spec. 223-224, 507Chemical Ionization Mass Spectrometer (CIMS) Shanhu Lee, Kent State University (http ionization mass spectrometry (PTR-CIMS). A typical CIMS instrument can be constructed from an ion source

  3. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrite and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O, and adsorbed H2O. The spectral character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micron, 2.2 micron, 2.7 micron, 3 micron, and 6 microns are reported here in spectra measured under a Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micron band depth is 8-17%; this band is much stronger under moist conditions. Under Marslike atmospheric conditions the 1.9-micron feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micron feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3-micron band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micron band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural OH features observed in these materials at 2.2-2.3 micron and 2.75 microns remain largely unaffected by the environmental conditions. A shift in the Christiansen feature towards shorter wavelengths has also been observed with decreasing atmospheric pressure and temperature in the midinfrared spectra of these samples.

  4. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrate and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O and adsorbed H2O. The spectal character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micrometers, 2.2 micrometers, 2.7 micrometers, 3 micrometers, and 6 micrometers are reported here in spetra measured under Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micrometer band depth is 8-17%; this band is much stonger under moist conditions. Under Marslike atmospheric conditions the 1.9-micrometer feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micrometer feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3- micrometer band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micromter band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural OH features observed in these materials at 2.2-2.3 micrometers and 2.27 micrometers remain largely unaffected by the environmental conditions. A shift in the Christiansen feature towards shorter wavelengths has also been observed with decreasing atmospheric pressure and temperature in the midinfrared spectra of these samples.

  5. DETERMINATION OF PHTHALATES IN WATER AND SOIL BY TANDEM MASS SPECTROMETRY UNDER CHEMICAL IONIZATION CONDITIONS WITH ISOBUTANE AS REAGENT GAS

    EPA Science Inventory

    Phthalate determination is important because phthalates often are major impurities in samples and can have significant health effects. Tandem mass spectrometry under chemical ionization mass spectrometry conditions with isobutane as the reagent gas was used to determine 11 phthal...

  6. Atmospheric pressure plasmas: infection control and bacterial responses.

    PubMed

    Mai-Prochnow, Anne; Murphy, Anthony B; McLean, Keith M; Kong, Michael G; Ostrikov, Kostya Ken

    2014-06-01

    Cold atmospheric pressure plasma (APP) is a recent, cutting-edge antimicrobial treatment. It has the potential to be used as an alternative to traditional treatments such as antibiotics and as a promoter of wound healing, making it a promising tool in a range of biomedical applications with particular importance for combating infections. A number of studies show very promising results for APP-mediated killing of bacteria, including removal of biofilms of pathogenic bacteria such as Pseudomonas aeruginosa. However, the mode of action of APP and the resulting bacterial response are not fully understood. Use of a variety of different plasma-generating devices, different types of plasma gases and different treatment modes makes it challenging to show reproducibility and transferability of results. This review considers some important studies in which APP was used as an antibacterial agent, and specifically those that elucidate its mode of action, with the aim of identifying common bacterial responses to APP exposure. The review has a particular emphasis on mechanisms of interactions of bacterial biofilms with APP. PMID:24637224

  7. Miniature differential mobility spectrometry using atmospheric pressure photoionization.

    PubMed

    Nazarov, Erkinjon G; Miller, Raanan A; Eiceman, Gary A; Stone, John A

    2006-07-01

    Positive and negative ion spectra have been obtained with a miniature differential mobility spectrometer equipped with a photoionization source operating at atmospheric pressure. With benzene as a dopant, providing C6H6+ as reactant ion, protonated molecular ions and proton-bound dimer ions were obtained with dimethyl methylphosphonate and butanone. The spectra obtained from gas chromatographic injections of aromatic hydrocarbons, benzene, toluene, and the xylenes, produced the molecular ions when the moisture level was very low, but at a high level the hydrated proton was also present. Possible mechanisms for the formation of protonated products are discussed. Negative ions were produced from electron capture by sulfur hexafluoride using benzene or acetone as dopant. Photoionization of nitrogen dioxide led to the formation of the nitrate ion whose yield was a nonlinear function of concentration. The use of a suitable dopant enhanced ion formation by up to 2 orders of magnitude, and limits of detection in both the positive and negative modes were all at the sub ppm(v) level. The study makes a strong case for the use of a photoionization source as an alternative to the radioactive 63Ni source. PMID:16808465

  8. Room-temperature atmospheric pressure plasma plume for biomedical applications

    SciTech Connect

    Laroussi, M.; Lu, X. [Electrical and Computer Engineering Department Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2005-09-12

    As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation.

  9. Pulsed, atmospheric pressure plasma source for emission spectrometry

    DOEpatents

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2004-05-11

    A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

  10. Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off

    NASA Technical Reports Server (NTRS)

    Sass, J. P.; Frontier, C. R.

    2007-01-01

    The Cryogenics Test Laboratory (CTL) at the Kennedy Space Center (KSC) routinely utilizes cryostat test hardware to evaluate comparative and absolute thermal conductivities of a wide array of insulation systems. The test method is based on measurement of the flow rate of gas evolved due to evaporative boil-off of a cryogenic liquid. The gas flow rate typically stabilizes after a period of a couple of hours to a couple of days, depending upon the test setup. The stable flow rate value is then used to calculate the thermal conductivity for the insulation system being tested. The latest set of identical cryostats, 1,000-L spherical tanks, exhibited different behavior. On a macro level, the flow rate did stabilize after a couple of days; however the stable flow rate was oscillatory with peak to peak amplitude of up to 25 percent of the nominal value. The period of the oscillation was consistently 12 hours. The source of the oscillation has been traced to variations in atmospheric pressure due to atmospheric tides similar to oceanic tides. This paper will present analysis of this phenomenon, including a calculation that explains why other cryostats are not affected by it.

  11. Infrared polarization spectroscopy of CO 2 at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Alwahabi, Z. T.; Li, Z. S.; Zetterberg, J.; Aldén, M.

    2004-04-01

    Polarisation spectroscopy (PS) was used to probe CO 2 gas concentration in a CO 2/N 2 binary mixture at atmospheric pressure and ambient temperature. The CO 2 molecules were probed by a direct laser excitation to an overtone and combination vibrational state. The tuneable narrow linewidth infrared laser radiation at 2 ?m was obtained by Raman shifting of the output from a single-longitudinal-mode pulsed alexandrite laser-system to the second Stokes component in a H 2 gas cell. Infrared polarisation spectroscopy (IRPS) and time-resolved infrared laser-induced fluorescence (IRLIF) spectra were collected. A linear dependence of the IRPS signal on the CO 2 mole fraction has been found. This indicates that the IRPS signal is only weakly affected by the molecular collisions and that the inter- and intra- molecular energy transfer processes do not strongly influence the molecular alignment at the time scale of the measurements. Thus IRPS holds great potential for quantitative instantaneous gas concentration diagnostics in general. This is especially important for molecules which do not posses an accessible optical transition such as CO, CO 2 and N 2O. In addition, an accurate experimental method to measure the extinction ratio of the IR polarisers employed in this study has been developed and applied. With its obvious merits as simplicity, easy alignment and high accuracy, the method can be generalized to all spectral regions, different polarisers and high extinction ratios.

  12. Measurement of viscosity of gaseous mixtures at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Mall, G. H.; Chegini, H.

    1986-01-01

    Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

  13. Atmospheric pressure nonthermal plasmas for bacterial biofilm prevention and eradication.

    PubMed

    Ermolaeva, Svetlana A; Sysolyatina, Elena V; Gintsburg, Alexander L

    2015-01-01

    Biofilms are three-dimensional structures formed by surface-attached microorganisms and their extracellular products. Biofilms formed by pathogenic microorganisms play an important role in human diseases. Higher resistance to antimicrobial agents and changes in microbial physiology make treating biofilm infections very complex. Atmospheric pressure nonthermal plasmas (NTPs) are a novel and powerful tool for antimicrobial treatment. The microbicidal activity of NTPs has an unspecific character due to the synergetic actions of bioactive components of the plasma torch, including charged particles, reactive species, and UV radiation. This review focuses on specific traits of biofilms, their role in human diseases, and those effects of NTP that are helpful for treating biofilm infections. The authors discuss NTP-based strategies for biofilm control, such as surface modifications to prevent bacterial adhesion, killing bacteria in biofilms, and biofilm destruction with NTPs. The unspecific character of microbicidal activity, proven polymer modification and destruction abilities, low toxicity for human tissues and absence of long-living toxic compounds make NTPs a very promising tool for biofilm prevention and control. PMID:25869456

  14. Power modulation in an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    Power modulation in an atmospheric pressure capacitively coupled radio frequency plasma jet is investigated by numerical modelling. The dynamics of successively pulsing the applied power on and off for a helium-oxygen (˜0.6%) plasma is investigated. The impact of power pulsing on reactive species generation and gas heating is discussed with control opportunities emphasized. Power modulation shows linear control for reactive species and heat flux delivery to a treatment surface above an initial phase of power growth. Power is found to be coupled primarily to the electrons with electron loss rates determining the interference between successive power modulation phases. Plasma decay in the power off phase is characterized by a large initial electron loss in the first 0.5 µs followed by ambipolar decay dominated by ions of opposite charge. Power modulation effects on gas heating show a larger range of temperature control when compared with convection cooling. Reactive oxygen species reaching a treatment surface are shown to typically vary over an order of magnitude for variation in the duty cycle.

  15. Form control in atmospheric pressure plasma processing of ground fused silica

    NASA Astrophysics Data System (ADS)

    Li, Duo; Wang, Bo; Xin, Qiang; Jin, Huiliang; Wang, Jun; Dong, Wenxia

    2014-08-01

    Atmospheric Pressure Plasma Processing (APPP) using inductively coupled plasma has demonstrated that it can achieve comparable removal rate on the optical surface of fused silica under the atmosphere pressure and has the advantage of inducing no sub-surface damage for its non-contact and chemical etching mechanism. APPP technology is a cost effective way, compared with traditional mechanical polishing, magnetorheological finishing and ion beam figuring. Thus, due to these advantages, this technology is being tested to fabricate large aperture optics of fused silica to help shorten the polishing time in optics fabrication chain. Now our group proposes to use inductively coupled plasma processing technology to fabricate ground surface of fused silica directly after the grinding stage. In this paper, form control method and several processing parameters are investigated to evaluate the removal efficiency and the surface quality, including the robustness of removal function, velocity control mode and tool path strategy. However, because of the high heat flux of inductively coupled plasma, the removal depth with time can be non-linear and the ground surface evolvement will be affected. The heat polishing phenomenon is founded. The value of surface roughness is reduced greatly, which is very helpful to reduce the time of follow-up mechanical polishing. Finally, conformal and deterministic polishing experiments are analyzed and discussed. The form error is less 3%, before and after the APPP, when 10?m depth of uniform removal is achieved on a 60×60mm ground fused silica. Also, a basin feature is fabricated to demonstrate the figuring capability and stability. Thus, APPP is a promising technology in processing the large aperture optics.

  16. Laser excitation dynamics of argon metastables generated in atmospheric pressure flows by microwave frequency microplasma arrays

    NASA Astrophysics Data System (ADS)

    Rawlins, W. T.; Galbally-Kinney, K. L.; Davis, S. J.; Hoskinson, A. R.; Hopwood, J. A.

    2014-03-01

    The optically pumped rare-gas metastable laser is a chemically inert analogue to diode-pumped alkali (DPAL) and alkali-exciplex (XPAL) laser systems. Scaling of these devices requires efficient generation of electronically excited metastable atoms in a continuous-wave electric discharge in flowing gas mixtures at atmospheric pressure. This paper describes initial investigations of the use of linear microwave micro-discharge arrays to generate metastable rare-gas atoms at atmospheric pressure in optical pump-and-probe experiments for laser development. Power requirements to ignite and sustain the plasma at 1 atm are low, <30 W. We report on the laser excitation dynamics of argon metastables, Ar (4s, 1s5) (Paschen notation), generated in flowing mixtures of Ar and He at 1 atm. Tunable diode laser absorption measurements indicate Ar(1s5) concentrations near 3 × 1012 cm-3 at 1 atm. The metastables are optically pumped by absorption of a focused beam from a continuous-wave Ti:S laser, and spectrally selected fluorescence is observed with an InGaAs camera and an InGaAs array spectrometer. We observe the optical excitation of the 1s5-->2p9 transition at 811.5 nm and the corresponding laser-induced fluorescence on the 2p10-->1s5 transition at 912.3 nm; the 2p10 state is efficiently populated by collisional energy transfer from 2p9. Using tunable diode laser absorption/gain spectroscopy, we observe small-signal gains of ~1 cm-1 over a 1.9 cm path. We also observe stable, continuous-wave laser oscillation at 912.3 nm, with preliminary optical efficiency ~55%. These results are consistent with efficient collisional coupling within the Ar(4s) manifold.

  17. Video Article Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure

    E-print Network

    Vertes, Akos

    Video Article Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure Bindesh the detailed protocol for single cell analysis using LAESI-MS. The presented video demonstrates the analysis., Vertes A. (2010). Direct Analysis of Single Cells by Mass Spectrometry at Atmospheric Pressure. JoVE. 43

  18. Dynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges

    E-print Network

    Raja, Laxminarayan L.

    . A relatively simple zero-dimensional model that treats only the Paschen breakdown mechanism in the dischargeDynamics of pulse phenomena in helium dielectric-barrier atmospheric-pressure glow discharges of pulse phenomena in conventional parallel-plate dielectric-barrier controlled atmospheric-pressure glow

  19. The initial responses of hot liquid water released under low atmospheric pressures: Experimental insights

    Microsoft Academic Search

    Alistair Simon Bargery; Alexander Barrett; Lionel Wilson; Jennie S. Gilbert

    2010-01-01

    Experiments have been performed to simulate the shallow ascent and surface release of water and brines under low atmospheric pressure. Atmospheric pressure was treated as an independent variable and water temperature and vapor pressure were examined as a function of total pressure variation down to low pressures. The physical and thermal responses of water to reducing pressure were monitored with

  20. PPPL-3281, Preprint: January 1998, UC-426 Synthesis of Ozone at Atmospheric Pressure

    E-print Network

    1 PPPL-3281, Preprint: January 1998, UC-426 Synthesis of Ozone at Atmospheric Pressure-coupled plasma (ICP) torch to synthesize ozone at atmospheric pressure is explored. Ozone concentrations up and ~11 kVA with an argon/oxygen mixture as the plasma-forming gas. A gaseous oxygen quench formed ozone

  1. Response of the Mediterranean mean sea level to atmospheric pressure forcing

    Microsoft Academic Search

    Pierre-Yves Le Traon; Philippe Gauzelin

    1997-01-01

    The response of the Mediterranean mean sea level to atmospheric pressure forcing is analyzed using 3 years of TOPEX\\/POSEIDON data. Coherence analysis between mean sea level and atmospheric pressure shows a significant departure from a standard inverse barometer effect at frequencies higher than 30days-1. At high frequencies the phase difference between sea level and pressure is about 100°, while it

  2. Interplay of discharge and gas flow in atmospheric pressure plasma jets Nan Jiang,1

    E-print Network

    Zexian, Cao

    Interplay of discharge and gas flow in atmospheric pressure plasma jets Nan Jiang,1 JingLong Yang,2 2011) Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three an optical schlieren system. Gas flow gains a forward momentum from discharge except for the case of overflow

  3. Three-dimensional gas temperature measurements in atmospheric pressure microdischarges using Raman scattering

    E-print Network

    Economou, Demetre J.

    Three-dimensional gas temperature measurements in atmospheric pressure microdischarges using Raman of small dimensions 100 s of micrometers , atmospheric pressure operation, and high power densities 10A discharge. © 2006 American Institute of Physics. DOI: 10.1063/1.2404594 High pressure nonequilibrium

  4. Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2

    E-print Network

    Kite, Edwin

    1 Constraints on early Mars atmospheric pressure1 inferred from small ancient craters2-dominated atmosphere, but direct constraints on paleoatmospheric11 pressure P are lacking. Of particular doubtful that increasing CO2 pressure (total atmospheric pressure, P) is enough to raise early39 Mars

  5. Microstreamer dynamics during plasma remediation of NO using atmospheric pressure dielectric barrier discharges

    E-print Network

    Kushner, Mark

    Microstreamer dynamics during plasma remediation of NO using atmospheric pressure dielectric- ate toxins from atmospheric pressure gas streams. Plasma remediation is one technique which has been methods for the removal of oxides of nitrogen NxOy from atmospheric gas streams and among those techniques

  6. Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals from sage leaves

    E-print Network

    Vertes, Akos

    Laser ablation atmospheric pressure photoionization mass spectrometry imaging of phytochemicals. In this contribution, we explore the feasibility of laser ablation atmospheric pressure photoionization (LAAPPI-time-of-flight (TOF)-MSI without any sample preparation. Leaf mass spectra were also recorded with laser ablation

  7. Gliding arc triggered microwave plasma arc at atmospheric pressure for coal gasification application

    NASA Astrophysics Data System (ADS)

    Jain, Vishal; Visani, A.; Patil, C.; Patel, B. K.; Sharma, P. K.; John, P. I.; Nema, S. K.

    2014-08-01

    Plasma torch is device that efficiently converts electrical energy in to thermal energy for various high temperature applications. The conventional plasma torch comprises of consumable electrodes namely anode and cathode electrodes. The replacement of these electrodes is a complex process owing to its cooling and process shut down requirements. However, microwave plasma arc is electrode-less plasma arc system that is an alternative method to conventional arc technology for generating plasma arc. In this technique, microwave power is efficiently coupled to generate plasma arc by using the property of polar molecule to absorb microwave power. The absorption of microwave power is in form of losses due to intermolecular friction and high collisions between the molecules. This is an efficient method because all microwave power can be absorbed by plasma arc. The main feature of microwave plasma arc is its large uniform high temperature column which is not possible with conventional arc discharge methods. Such type of plasma discharge is very useful in applications where sufficient residence time for treat materials is required. Microwave arc does not require any consumable electrodes and hence, it can be operated continuously that makes it very useful for hazardous effluent treatment applications. Further, microwave cannot ionize neutral particles at atmospheric pressure and hence, a gliding arc is initiated between two thin electrodes in the cavity by applying very low power high voltage (3kV) AC source. In this report, the method for generating microwave arc of 1kW power using commercial microwave oven is elaborated.

  8. Temporally-Resolved Emission Spectroscopic Diagnostics of the Atmospheric Pressure Glow Discharge in Helium

    NASA Astrophysics Data System (ADS)

    Liu, Yaoge; Hao, Yanpeng; Zheng, Bin

    2013-09-01

    Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges (DBDs) in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device (ICCD) and a grating spectrometer, we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs. We also studied the time variation of typical emissions from He, O and first negative bands of N+2. The results showed that the spectral lines do not develop synchronously as N+2(B2 ?u + X2 ?+g, 0~0, ?=391.4 nm) and N+2(B2 ?+u ? X2 ?+g, 0~1, ?=427.8 nm) appear earlier and last for a longer time than He (33S1 ? 23P1, ?=706.5 nm) and O (35P?35S, ?=777.4 nm). A certain number of He metastables produced in the initial stage of discharge. Even between adjacent pulses, the emissions from N+2 can still keep certain intensities while those from He and O extinguish. Since long-lifetime He metastables are produced and exist in the discharging space, it is the Penning ionization that keeps the long decay of N+2 emissions.

  9. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    SciTech Connect

    Stark, C. R.; Helling, Ch.; Rimmer, P. B. [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS (United Kingdom); Diver, D. A., E-mail: craig.stark@st-andrews.ac.uk [SUPA, School of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

    2013-10-10

    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (?10{sup –7}) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10{sup –6}-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H{sub 2}, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

  10. Focusing of Ions in Atmospheric Pressure Gases Using Electrostatic Fields.

    NASA Astrophysics Data System (ADS)

    Potjewyd, John

    It has become increasingly important to improve the sensitivity of instruments that sample ions in atmospheric pressure gases from diffuse ion sources such as flames in air, ambient ions in air, and sprays, by introducing ions more efficiently into the analyzer region. Although the present state of mass spectroscopy is highly developed, a signal gain of a factor of two is deemed to be very significant. A prototype electrostatic lens system has been developed that demonstrates the feasibility of focusing ions toward a sampling orifice from various ion sources using spherically converging fields applied with a resistive thick film lens. The limit of a zero space charge ion source was investigated with a differential ion beam showing that gains in sensitivity can be on the order of 100 despite the observed field asymmetry. As part of this study, the ion flow in the micro-region approaching the vacuum orifice was analyzed, experimentally and theoretically, taking into account the combined effect of fluid motion and ion drift due to electric fields. Ions drifting toward the orifice plate are collected from an area larger than the orifice by a ratio which depends inversely on the field strength. Gains achievable by this system with an intense corona discharge ion source were examined to study effects of space charge. In order to maximize gain with the space charge fields present required the application of stronger focusing fields, strengthening the bias field, so that overall gain is reduced by the offsetting effect of the decrease in ion sampling area. Nevertheless, significant improvements in sensitivity, typically three times that of a non-focusing system, were observed. Thus the ion focusing system is of real benefit even with intense ion sources.

  11. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    SciTech Connect

    Begum, Asma [Independent University, Bangladesh, School of Engineering and Computer Science, Bashundhara, Dhaka (Bangladesh); Laroussi, Mounir [Old Dominion University, Department of Electrical and Computer Engineering, Norfolk, Virginia (United States); Pervez, Mohammad Rasel [Master Mind College, Department of Physics, Dhanmondi, Dhaka (Bangladesh)

    2013-06-15

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

  12. Tailoring electron energy distribution functions through energy confinement in dual radio-frequency driven atmospheric pressure plasmas

    SciTech Connect

    O'Neill, C.; Waskoenig, J. [Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom); Gans, T. [Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2012-10-08

    A multi-scale numerical model based on hydrodynamic equations with semi-kinetic treatment of electrons is used to investigate the influence of dual frequency excitation on the effective electron energy distribution function (EEDF) in a radio-frequency driven atmospheric pressure plasma. It is found that variations of power density, voltage ratio, and phase relationship provide separate control over the electron density and the mean electron energy. This is exploited to directly influence both the phase dependent and time averaged effective EEDF. This enables tailoring the EEDF for enhanced control of non-equilibrium plasma chemical kinetics at ambient pressure and temperature.

  13. Real-time monitoring of volatile organic compounds using chemical ionization mass spectroscopy: Final report

    SciTech Connect

    Thornberg, S.M.; Mowry, C.D.; Keenan, M.R.; Bender, S.F.A. [Sandia National Labs., Albuquerque, NM (United States). Gas Analysis Lab.; Owen, T. [Intel Corp., Rio Rancho, NM (United States)

    1997-04-01

    Volatile organic compound (VOC) emission to the atmosphere is of great concern to semiconductor manufacturing industries, research laboratories, the public, and regulatory agencies. Some industries are seeking ways to reduce emissions by reducing VOCs at the point of use (or generation). This paper discusses the requirements, design, calibration, and use of a sampling inlet/quadrupole mass spectrometer system for monitoring VOCs in a semiconductor manufacturing production line. The system uses chemical ionization to monitor compounds typically found in the lithography processes used to manufacture semiconductor devices (e.g., acetone, photoresist). The system was designed to be transportable from tool to tool in the production line and to give the operator real-time feedback so the process(es) can be adjusted to minimize VOC emissions. Detection limits ranging from the high ppb range for acetone to the low ppm range fore other lithography chemicals were achieved using chemical ionization mass spectroscopy at a data acquisition rate of approximately 1 mass spectral scan (30 to 200 daltons) per second. A demonstration of exhaust VOC monitoring was performed at a working semiconductor fabrication facility during actual wafer processing.

  14. Development and Characterization of a Hybrid Atmospheric Pressure Plasma Electrospinning System for Nanofiber Enhancement

    NASA Astrophysics Data System (ADS)

    Nowak, Joshua Michael

    A hybrid atmospheric pressure-electrospinning plasma system was developed to be used for the production of nanofibers and enhance their performance for various applications. Electrospun nanofibers are excellent candidates for protective clothing in the field of chemical and biological warfare defense; however, nanofibers are structurally weak and easily abrade and tear. They can be strengthened through the support of a substrate fabric, but they do not adhere well to substrates. Through the use of the developed hybrid system with either pure He or He/O2 (99/1) feed gas, adherence to the substrate along with abrasion and flex resistance were improved. The plasma source was diagnosed electrically, thermally, and optically. An equivalent circuit model was developed for non-thermal, highly collisional plasmas that can solve for average electron temperature and electron number density. The obtained temperatures (~ 3eV) correlate very well with the results of a neutral Bremsstrahlung continuum matching technique that was also employed. Using the temperatures and number densities obtained from the circuit model and the optical spectroscopy, a global chemical kinetics code was written in order to solve for radical and ion concentrations. This code shows that there are significant concentrations of oxygen radicals present. The XPS analysis confirmed that there was an increase of surface oxygen from 11.1% up to 16.6% for the He/O2 plasma and that the C-O bonding, which was not present in the control samples, has increased to 45.4%. The adhesive strength to the substrate has a significant increase of 81% for helium plasma and 144% for He/O2 plasma; however, these values remain below the desired values for protective clothing applications. The hybrid system displayed the ability to oxygenate nanofibers as they are being electrospun and shows the feasibility of making other surface modifications. The developed circuit model and chemical kinetics code both show promise as tools for deterministic atmospheric pressure plasma research in the field of surface modifications.

  15. Analysis of Biomolecules by Atmospheric Pressure Visible-Wavelength MALDI-Ion Trap-MS in Transmission Geometry

    NASA Astrophysics Data System (ADS)

    West, Raymond E.; Findsen, Eric W.; Isailovic, Dragan

    2013-10-01

    We report the development of a new AP visible-wavelength MALDI-ion trap-MS instrument with significantly improved performance over our previously reported system ( Int. J. Mass Spectrom. 315, 66-73 (2012)). A Nd:YAG pulsed laser emitting light at 532 nm was used to desorb and ionize oligosaccharides and peptides in transmission geometry through a glass slide. Limits of detection (LODs) achieved in MS mode correspond to picomole quantities of oligosaccharides and femtomole quantities of peptides. Tandem MS (MS/MS) experiments enabled identification of enzymatically digested proteins and oligosaccharides by comparison of MS/MS spectra with data found in protein and glycan databases. Moreover, the softness of ionization, LODs, and fragmentation spectra of biomolecules by AP visible-wavelength MALDI-MS were compared to those obtained by AP UV MALDI-MS using a Nd:YAG laser emitting light at 355 nm. AP visible-wavelength MALDI appears to be a softer ionization technique then AP UV MALDI for the analysis of sulfated peptides, while visible-wavelength MALDI-MS, MS/MS, and MS/MS/MS spectra of other biomolecules analyzed were mostly similar to those obtained by AP UV MALDI-MS. Therefore, the methodology presented will be useful for MS and MSn analyses of biomolecules at atmospheric pressure. Additionally, the AP visible-wavelength MALDI developed can be readily used for soft ionization of analytes on various mass spectrometers.

  16. Delayed responses of analyte emission in a pulse-modulated direct-current argon arc at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Kuzmanovi?, M.; Savovi?, J.; Pavlovi?, M. S.; Stoiljkovi?, M.; Rankovi?, D.; Mom?ilovi?, M.

    2010-12-01

    A pulse-modulated direct-current argon arc burning at atmospheric pressure has been investigated by analyzing temporally and spatially resolved analyte emission responses in a millisecond time domain. The arc current was a rectangular pulse modulated between 9 and 3.5 A with a modulation period of 250 ms and a low current interval of up to 50 ms. Both positive and negative step modulation in current strongly affected the analyte emission. Delayed responses of representative analytes with ionization energies ranging from 6.5 to 10 eV have been studied. Depending on the analyte ionization energy and the plasma zone observed, a sudden current change was in most cases followed by a line intensity increase. The magnitude of this increase is correlated with changes in the ionization-recombination balance, the extent of demixing and the gas dynamics processes invoked by a current modulation. For analytes with medium and low ionization energies a current drop is accompanied by a large increase in signal-to-background ratio, which opens up the possibility of the use of arc current modulation for sensitivity improvement.

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

    NASA Astrophysics Data System (ADS)

    Brüggemann, Martin; Hoffmann, Thorsten

    2014-05-01

    Organic aerosol accounts for a substantial fraction of tropospheric aerosol and has implications on the earth's climate and human health. However, the characterization of its chemical composition and transformations remain a major challenge and is still connected to large uncertainties (IPCC, 2013). Recent measurements revealed that organic aerosol particles may reside in an amorphous or semi-solid phase state which impedes the diffusion within the particles (Virtanen et al., 2010; Shiraiwa et al., 2011). This means that reaction products which are formed on the surface of a particle, e.g. by OH, NO3 or ozone chemistry, cannot diffuse into the particle's core and remain at the surface. Eventually, this leads to particles with a core/shell structure. In the particles' cores the initial compounds are preserved whereas the shells contain mainly the oxidation products. By analyzing the particles' cores and shells separately, thus, it is possible to obtain valuable information on the formation and evolution of the aerosols' particle and gas phase. Here we present the development of the aerosol flowing atmospheric-pressure afterglow (AeroFAPA) technique which allows the mass spectrometric analysis of organic aerosols in real time. The AeroFAPA is an ion source based on a helium glow discharge at atmospheric pressure. The plasma produces excited helium species and primary reagent ions which are transferred into the afterglow region where the ionization of the analytes takes place. Due to temperatures of only 80 ° C to 150 ° C and ambient pressure in the afterglow region, the ionization is very soft and almost no fragmentation of organic molecules is observed. Thus, the obtained mass spectra are easy to interpret and no extensive data analysis procedure is necessary. Additionally, first results of a combination of the AeroFAPA-MS with a scanning mobility particle sizer (SMPS) suggest that it is not only possible to analyze the entire particle phase but rather that a separate analysis of the particles' shells and cores is feasible by adjusting flow rates and temperatures in the ionization region. References: IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, in press. A. Virtanen; J. Joutsensaari; T. Koop; J. Kannosto; P. Yli-Pirila; J. Leskinen; J. M. Makela; J. K. Holopainen; U. Pöschl; M. Kulmala; D. R. Worsnop; A. Laaksonen, "An amorphous solid state of biogenic secondary organic aerosol particles", Nature 7317, 824-827 [2010]. M. Shiraiwa; M. Ammann; T. Koop; U. Pöschl, "Gas uptake and chemical aging of semisolid organic aerosol particles", P. Natl. Acad. Sci. USA 27, 11003-11008 [2011].

  18. Picoelectrospray ionization mass spectrometry using narrow-bore chemically etched emitters

    PubMed Central

    Marginean, Ioan; Tang, Keqi; Smith, Richard D.; Kelly, Ryan T.

    2013-01-01

    Electrospray ionization mass spectrometry (ESI-MS) at flow rates below ~10 nL/min has been only sporadically explored due to difficulty in reproducibly fabricating emitters that can operate at lower flow rates. Here we demonstrate narrow orifice chemically etched emitters for stable electrospray at flow rates as low as 400 pL/min. Depending on the analyte concentration, we observe two types of MS signal response as a function of flow rate. At low concentrations, an optimum flow rate is observed slightly above 1 nL/min, while the signal decreases monotonically with decreasing flow rates at higher concentrations. For example, consumption of 500 zmol of sample yielded signal-to-noise ratios ~10 for some peptides. In spite of lower MS signal, the ion utilization efficiency increases exponentially with decreasing flow rate in all cases. Significant variations in ionization efficiency were observed within this flow rate range for an equimolar mixture of peptides, indicating that ionization efficiency is an analyte-dependent characteristic for the present experimental conditions. Mass-limited samples benefit strongly from the use of low flow rates and avoiding unnecessary sample dilution. These findings have important implications for the analysis of trace biological samples. PMID:24122304

  19. Driven motion and instability of an atmospheric pressure arc

    NASA Astrophysics Data System (ADS)

    Karasik, Max

    Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental are furnace is constructed and operated in air with graphite cathode and steel anode at currents 100--250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes. Experiments are carried out on the response of the are to applied transverse DC and AC (up to ?1 kHz) magnetic fields. The arc is found to deflect parabolically for DC field and assumes a growing sinusoidal structure for AC field. A simple analytic two-parameter fluid model of the are dynamics is derived, in which the inertia of the magnetically pumped cathode jet balances the applied J?xB? force. Time variation of the applied field allows evaluation of the parameters individually. A fit of the model to the experimental data gives a value for the average jet speed an order of magnitude below Maecker's estimate of the maximum jet speed. A spontaneous instability of the same arc is investigated experimentally and modeled analytically. The presence of the instability is found to depend critically on cathode dimensions. For cylindrical cathodes, instability occurs only for a narrow range of cathode diameters. Cathode spot motion is proposed as the mechanism of the instability. A simple fluid model combining the effect of the cathode spot motion and the inertia of the cathode jet successfully describes the arc shape during low amplitude instability. The amplitude of cathode spot motion required by the model is in agreement with measurements. The average jet velocity required is approximately equal to that inferred from the transverse magnetic field experiments. Reasons for spot motion and for cathode geometry dependence are discussed. An exploratory study of the instability of the arc in applied axial magnetic field is also described. Applicability of the results of the thesis to an industrial steelmaking furnace is considered.

  20. Surface treatment of aramid fiber by air dielectric barrier discharge plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Jia, Caixia; Chen, Ping; Liu, Wei; Li, Bin; Wang, Qian

    2011-02-01

    Aramid fiber samples are treated by air dielectric barrier discharge (DBD) plasma at atmospheric pressure; the plasma treatment time is investigated as the major parameter. The effects of this treatment on the fiber surface physical and chemical properties are studied by using surface characterization techniques. Scanning electron microscopy (SEM) is performed to determine the surface morphology changes, X-ray photoelectron spectroscopy (XPS) is analyzed to reveal the surface chemical composition variations and dynamic contact angle analysis (DCAA) is used to examine the changes of the fiber surface wettability. In addition, the wetting behavior of a kind of thermoplastic resin, poly(phthalazinone ether sulfone ketone) (PPESK), on aramid fiber surface is also observed by SEM photos. The study shows that there seems to be an optimum treatment condition for surface modification of aramid fiber by the air DBD plasma. In this paper, after the 12 s, 27.6 W/cm3 plasma treatment the aramid fiber surface roughness is significantly improved, some new oxygen-containing groups such as C-O, Cdbnd O and Odbnd C-O are generated on the fiber surface and the fiber surface wettability is greatly enhanced, which results in the better wetting behavior of PPESK resin on the plasma-treated aramid fiber.

  1. Atmospheric pressure drives changes in the vertical distribution of biogenic free-phase gas in a northern peatland

    Microsoft Academic Search

    Xavier Comas; Lee Slater; A. S. Reeve

    2011-01-01

    Gas content in deep peat soils is larger and less variable than shallow peatIncreases in atmospheric pressure result in gas release from shallow peatDecreases in atmospheric pressure result in upward gas movement

  2. Quantitation of Benzo[a]pyrene Metabolic Profiles in Human Bronchoalveolar H358) Cells by Stable Isotope Dilution Liquid Chromatography-Atmospheric Chemical Ionization Mass Spectrometry

    PubMed Central

    Lu, Ding; Harvey, Ronald G.; Blair, Ian A.; Penning, Trevor M.

    2013-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and are carcinogenic in multiple organs and species. Benzo[a]pyrene (B[a]P) is a representative PAH and has been studied extensively for its carcinogenicity and toxicity. B[a]P itself is chemically inert and requires metabolic activation to exhibit its toxicity and carcinogenicity. Three major metabolic pathways have been well documented. The signature metabolites generated from the radical cation (peroxidase or monooxygenase mediated) pathway are B[a]P-1,6-dione and B[a]P-3,6-dione, the signature metabolite generated from the diol-epoxide (P450 mediated) pathway is B[a]P-r-7,t-8,t-9,c-10-tetrahydrotetrol (B[a]P-tetrol-1) and the signature metabolite generated from the o-quinone (aldo-keto reductase mediated) pathway is B[a]P-7,8-dione. The contributions of these different metabolic pathways to cancer initiation and the exploitation of this information for cancer prevention are still under debate. With the availability of a library of [13C4]-labeled B[a]P metabolite internal standards, we developed a sensitive stable isotope dilution atmospheric pressure chemical ionization tandem mass spectrometry method to address this issue by quantitating B[a]P metabolites from each metabolic pathway in human lung cells. This analytical method represents a 500 fold increased sensitivity compared with a method using HPLC-radiometric detection. The limit of quantitation (LOQ) was determined to be 6 fmol on column for 3-hydroxybenzo[a]pyrene (3-OH-B[a]P), the generally accepted biomarker for B[a]P exposure. This high level of sensitivity and robustness of the method was demonstrated in a study of B[a]P metabolic profiles in human bronchoalveolar H358 cells induced or uninduced with the AhR ligand, 2,3,7,8-tetrachlorodibenzodioxin (TCDD). All the signature metabolites were detected and successfully quantitated. Our results suggest that all three metabolic pathways contribute equally in the overall metabolism of B[a]P in H358 cells with or without TCDD induction. The sensitivity of the method should permit the identification of cell-type differences in B[a]P activation and detoxication and could also be used for biomonitoring human exposure to PAH. PMID:21962213

  3. Characterization of pyrogenic black carbon by desorption atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Podgorski, David C; Hamdan, Rasha; McKenna, Amy M; Nyadong, Leonard; Rodgers, Ryan P; Marshall, Alan G; Cooper, William T

    2012-02-01

    We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C and O/C ratios. The bimodal distribution of aromatic and aliphatic compounds observed in the combusted oak sample is attributed to incomplete thermal degradation of lignin and hemicellulose. Pyrolyzed oak constituents exhibit lower H/C and O/C ratios: approximately three-quarters of the identified species are aromatic. DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy. Complete molecular characterization of biomass upon thermal transformation may provide insight into the biogeochemical cycles of biochar and future renewable energy sources, particularly for samples currently limited by solubility, separation, and sample preparation. PMID:22242739

  4. Diamond and Related Materials, 2 (1993) 661 666 661 Degenerate four-wave mixing diagnostics of atmospheric pressure

    E-print Network

    Zare, Richard N.

    of atmospheric pressure diamond deposition T. G. Owano and C. H. Kruger Iti~'4h7~,mperatureGasdynamies Laboratory of atmospheric pressure diamond synthesis reactors are evaluated. Benefits and disadvantages of optical emission (DFWM), are discussed in terms of their applicability to the harsh environment of atmospheric pressure

  5. Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures

    E-print Network

    Harilal, S. S.

    in argon gas at atmospheric pressures Alexander Miloshevsky, Sivanandan S. Harilal, Gennady Miloshevsky formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures. VC plasma expansion into a background gas at atmospheric pressure is cru- cial for many engineering

  6. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    E-print Network

    Boyer, Edmond

    in air at atmospheric pressure David Z. Pai,a Deanna A. Lacoste, and Christophe O. Laux Laboratoire EM2C January 2010; published online 6 May 2010 In atmospheric pressure air preheated from 300 to 1000 K.1063/1.3309758 I. INTRODUCTION Atmospheric pressure air plasmas have potential appli- cations in biomedical

  7. The emissions of gases from abandoned mines: role of atmospheric pressure changes and air temperature on the surface

    E-print Network

    Boyer, Edmond

    1 The emissions of gases from abandoned mines: role of atmospheric pressure changes and air . Atmospheric pressure . Air temperature on the surface . Exits . Open or closed old mining voids Introduction, atmospheric pressure, speed and direction of the wind have also effects on mine gas outflow or atmospheric gas

  8. Quasi-trapping chemical ionization source based on a commercial VUV lamp for time-of-flight mass spectrometry.

    PubMed

    Chen, Ping; Hou, Keyong; Hua, Lei; Xie, Yuanyuan; Zhao, Wuduo; Chen, Wendong; Chen, Chuang; Li, Haiyang

    2014-02-01

    The application of VUV lamp-based single photon ionization (SPI) was limited due to low photon energy and poor photon flux density. In this work, we designed a quasi-trapping chemical ionization (QT-CI) source with a commercial VUV 10.6 eV krypton lamp for time-of-flight mass spectrometry. The three electrode configuration ion source with RF voltage on the second electrode constitutes a quasi-trapping region, which has two features: accelerating the photoelectrons originated from the photoelectric effect with VUV light to trigger the chemical ionization through ion-molecule reaction and increasing the collisions between reactant ion O2(+) and analyte molecules to enhance the efficiency of chemical ionization. Compared to single SPI based on VUV krypton lamp, the QT-CI ion source not only apparently improved the sensitivity (e.g., 12-118 fold enhancement were achieved for 13 molecules, including aromatic hydrocarbon, chlorinated hydrocarbon, hydrogen sulfide, etc.) but also extended the range of ionizable molecules with ionization potential (IP) higher than 10.6 eV, such as propane, dichloroethane, and trichloromethane. PMID:24428693

  9. Preflame zone structure and main features of fuel conversion in atmospheric pressure premixed laminar hydrocarbon flames

    SciTech Connect

    Ksandopulo, G.I.

    1995-08-25

    This report describes the structure study of the premixed hydrocarbon-oxidizer Bunsen flames burning at the atmospheric pressure and also the ones with some inhibitors added. Studies were performed on hexane, propane, methane, acetylene, and hexene flames.

  10. Surface atmospheric pressure excitation of the translational mode of the inner , J.-P. Boy

    E-print Network

    Paris-Sud XI, Université de

    for Environmental Prediction) Climate Forecast System Reanalysis (CFSR) models, we show that atmospheric pressure a challenging instrumental task for the near future. Keywords: Slichter mode; ECMWF atmospheric model; NCEP/CFSR

  11. FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS IN AN ATMOSPHERIC PRESSURE ETHYLENE DIFFUSION FLAME. (R825412)

    EPA Science Inventory

    Abstract The microstructure of an atmospheric pressure, counterflow, sooting, flat, laminar ethylene diffusion flame has been studied experimentally by withdrawing samples from within the flame using a heated quartz microprobe coupled to an online gas chromatograph/mas...

  12. Optical emission study of a directcurrent, atmospheric-pressure nonthermal plasma microjet

    Microsoft Academic Search

    WeiDong Zhu; J. Lopez; K. H. Becker

    2010-01-01

    Summary form only given. Over the past few years, various atmospheric-pressure plasma jets were developed, most of which operate at radio frequency or pulsed DC power with inert gases such as He as the working gas of choice. This work aims to study a direct current driven, atmospheric-pressure non-thermal plasma microjet (PMJ) operated in air and in water with a

  13. Dissociation of nitrogen in a pulse-periodic dielectric barrier discharge at atmospheric pressure

    SciTech Connect

    Popov, N. A., E-mail: npopov@mics.msu.su [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2013-05-15

    Nitrogen molecule dissociation in a pulse-periodic atmospheric-pressure dielectric barrier discharge is numerically analyzed. It is shown that the quenching rate of predissociation states at atmospheric pressure is relatively low and the production of nitrogen atoms in this case can be adequately described using the cross section for electron-impact dissociation of N{sub 2} molecules taken from the paper by P.C. Cosby [J. Chem. Phys. 98, 9544 (1993)].

  14. Plasma-polymerized tetrafluoroethylene coatings on silica particles by atmospheric-pressure glow discharge

    Microsoft Academic Search

    Yasushi Sawada; Masuhiro Kogama

    1997-01-01

    This paper presents a method of novel plasma treatment for fine particles by the atmospheric-pressure glow (APG) discharge, in which particles were circulated and repeatedly plasma-treated at atmospheric pressure. Using this method, plasma-polymerized tetrafluoroethylene (TFE) film formations on the porous granulated silica particles of 152 ?m mean diameter were investigated. The XPS C(1s) spectrum of the treated surfaces deconvoluted into

  15. Nanosecond Repetitively Pulsed Discharge of Point–Plane Gaps in Air at Atmospheric Pressure

    Microsoft Academic Search

    Tao Shao; Cheng Zhang; Hui Jiang; Zheng Niu; Ping Yan; Yuanxiang Zhou

    2011-01-01

    Atmospheric-pressure gas discharge excited by high- voltage pulses with fast rise time and short duration has at- tracted significant attention for various applications. In this paper, discharges are generated in a highly nonuniform electric field by point-plane gaps in air at atmospheric pressure by a solid-state repetitive nanosecond-pulse generator. Under different experimental conditions, the applied voltage, discharge current, and discharge

  16. Liquid sampling-atmospheric pressure glow discharge as a secondary excitation source: Assessment of plasma characteristics

    NASA Astrophysics Data System (ADS)

    Manard, Benjamin T.; Gonzalez, Jhanis J.; Sarkar, Arnab; Dong, Meirong; Chirinos, Jose; Mao, Xianglei; Russo, Richard E.; Marcus, R. Kenneth

    The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as a secondary excitation source with a parametric evaluation regarding carrier gas flow rate, applied current, and electrode distance. With this parametric evaluation, plasma optical emission was monitored in order to obtain a fundamental understanding with regards to rotational temperature (Trot), excitation temperature (Texc), electron number density (ne), and plasma robustness. Incentive for these studies is not only for a greater overall fundamental knowledge of the APGD, but also in instrumenting a secondary excitation/ionization source following laser ablation (LA). Rotational temperatures were determined through experimentally fitting of the N2 and OH molecular emission bands while atomic excitation temperatures were calculated using a Boltzmann distribution of He and Mg atomic lines. The rotational and excitation temperatures were determined to be ~ 1000 K and ~ 2700 K respectively. Electron number density was calculated to be on the order of ~ 3 × 1015 cm- 3 utilizing Stark broadening effects of the H? line of the Balmer series and a He I transition. In addition, those diagnostics were performed introducing magnesium (by solution feed and laser ablation) into the plasma in order to determine any perturbation under heavy matrix sampling. The so-called plasma robustness factor, derived by monitoring Mg II/Mg I emission ratios, is also employed as a reflection of potential perturbations in microplasma energetics across the various operation conditions and sample loadings. While truly a miniaturized source (< 1 mm3 volume), the LS-APGD is shown to be quite robust with plasma characteristics and temperatures being unaffected upon introduction of metal species, whether by liquid or laser ablation sample introduction.

  17. Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    SciTech Connect

    Prevosto, L.; Mancinelli, B. R. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina) and Instituto de Fisica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales UBA Ciudad Universitaria Pab. I, (1428) Buenos Aires (Argentina)

    2012-09-15

    Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

  18. Disinfection of Ocular Cells and Tissues by Atmospheric-Pressure Cold Plasma

    PubMed Central

    Vono, Maria; Venier, Paola; Tarricone, Elena; Deligianni, Velika; Martines, Emilio; Zuin, Matteo; Spagnolo, Silvia; Cavazzana, Roberto; Cardin, Romilda; Castagliuolo, Ignazio; La Gloria Valerio, Alvise; Leonardi, Andrea

    2012-01-01

    Background Low temperature plasmas have been proposed in medicine as agents for tissue disinfection and have received increasing attention due to the frequency of bacterial resistance to antibiotics. This study explored whether atmospheric-pressure cold plasma (APCP) generated by a new portable device that ionizes a flow of helium gas can inactivate ocular pathogens without causing significant tissue damage. Methodology/Principal Findings We tested the APCP effects on cultured Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Candida albicans, Aspergillus fumigatus and Herpes simplex virus-1, ocular cells (conjunctival fibroblasts and keratocytes) and ex-vivo corneas. Exposure to APCP for 0.5 to 5 minutes significantly reduced microbial viability (colony-forming units) but not human cell viability (MTT assay, FACS and Tunel analysis) or the number of HSV-1 plaque-forming units. Increased levels of intracellular reactive oxygen species (ROS) in exposed microorganisms and cells were found using a FACS-activated 2?,7?-dichlorofluorescein diacetate probe. Immunoassays demonstrated no induction of thymine dimers in cell cultures and corneal tissues. A transient increased expression of 8-OHdG, genes and proteins related to oxidative stress (OGG1, GPX, NFE2L2), was determined in ocular cells and corneas by HPLC, qRT-PCR and Western blot analysis. Conclusions A short application of APCP appears to be an efficient and rapid ocular disinfectant for bacteria and fungi without significant damage on ocular cells and tissues, although the treatment of conjunctival fibroblasts and keratocytes caused a time-restricted generation of intracellular ROS and oxidative stress-related responses. PMID:22432007

  19. Atmospheric pressure plasma cleaning of contamination surfaces. 1997 mid-year progress report

    SciTech Connect

    Selwyn, G.S. [Los Alamos National Lab., NM (US); Hicks, R. [Univ. of California, Los Angeles, CA (US)

    1997-06-01

    'Goals of the project are to (1) identify the key physics and chemistry underlying the use of high pressure plasmas for etching removal of actinides and actinide surrogates; and (2) identify key surface reactions and plasma physics necessary for optimization of the atmospheric pressure plasma jet. Technical description of the work decommissioning of transuranic waste (TRU) into low-level radioactive waste (LLW) represents the largest cleanup cost associated with the nuclear weapons complex. This work is directed towards developing a low-cost plasma technology capable of converting TRU into LLW, based upon highly selective plasma etching of plutonium and other actinides from contaminated surfaces. In this way, only the actinide material is removed, leaving the surface less contaminated. The plasma etches actinide material by producing a volatile halide compound, which may be efficiently trapped using filters. To achieve practical, low-cost operation of a plasma capable of etching actinide materials, the authors have developed a y-mode, resonant-cavity, atmospheric pressure plasma jet (APPJ). In contrast to conventional, low pressure plasmas, the APPJ produces a purely-chemical effluent free of ions, and so achieves very high selectivity and produces negligible damage to the surface. Since the jet operates outside a chamber, many nuclear wastes may be treated including machinery, duct-work, concrete and other building materials. In some cases, it may be necessary to first remove paint from contaminated surfaces using a plasma selective for that surface, then to switch to the actinide etching chemistry for removal of actinide contamination. The goal of this work is to develop the underlying science required for maturation of this technology and to establish early version engineering prototypes. Accomplishments to Date The authors have made significant progress in this program. The work conducted jointly at Los Alamos and at UCLA. This has been facilitated by exchange of people, equipment and designs between the two locations. The study can be divided into three (3) components: (1) source design, operation and physics, (2) effluent characterization and analysis, (3) surface reactions and decontamination. Some of the key accomplishments in each area are noted.'

  20. Atmospheric pressure synthesis of photoluminescent hybrid materials by sequential organometallic vapor infiltration into polyethylene terephthalate fibers

    NASA Astrophysics Data System (ADS)

    Akyildiz, Halil I.; Mousa, Moataz Bellah M.; Jur, Jesse S.

    2015-01-01

    Exposing a polymer to sequential organometallic vapor infiltration (SVI) under low pressure conditions can significantly modify the polymer's chemical, mechanical, and optical properties. We demonstrate that SVI of trimethylaluminum into polyethylene terephthalate (PET) can also proceed readily at atmospheric pressure, and at 60 °C the extent of reaction determined by mass uptake is independent of pressure between 2.5 Torr and 760 Torr. At 120 °C, however, the mass gain is 50% larger at 2.5 Torr relative to that at 760 Torr, indicating that the precursor diffusion in the chamber and fiber matrix decreases at higher source pressure. Mass gain decreases, in general, as the SVI process temperature increases both at 2.5 Torr and 760 Torr attributed to the faster reaction kinetics forming a barrier layer, which prevents further diffusion of the reactive species. The resulting PET/Al-Ox product shows high photoluminescence compared to untreated fibers. A physical mask on the polymer during infiltration at 760 Torr is replicated in the underlying polymer, producing an image in the polymer that is visible under UV illumination. Because of the reduced precursor diffusivity during exposure at 760 Torr, the image shows improved resolution compared to SVI performed under typical 2.5 Torr conditions.

  1. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation

    PubMed Central

    2013-01-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution. PMID:23634893

  2. Localized etching of polymer films using an atmospheric pressure air microplasma jet

    NASA Astrophysics Data System (ADS)

    Guo, Honglei; Liu, Jingquan; Yang, Bin; Chen, Xiang; Yang, Chunsheng

    2015-01-01

    A direct-write process device based on the atmospheric pressure air microplasma jet (A?PJ) has been developed for the localized etching of polymer films. The plasma was generated by the air discharge ejected out through a tip-nozzle (inner diameter of 100??m), forming the microplasma jet. The A?PJ was capable of reacting with the polymer surface since it contains a high concentration of oxygen reactive species and thus resulted in the selective removal of polymer films. The experimental results demonstrated that the A?PJ could fabricate different microstructures on a parylene-C film without using any masks or causing any heat damage. The etch rate of parylene-C reached 5.1??m?min?1 and microstructures of different depth and width could also be realized by controlling two process parameters, namely, the etching time and the distance between the nozzle and the substrate. In addition, combining XPS analysis and oxygen-induced chemical etching principles, the potential etching mechanism of parylene-C by the A?PJ was investigated. Aside from the etching of parylene-C, micro-holes on the photoresist and polyimide film were successfully created by the A?PJ. In summary, maskless pattern etching of polymer films could be achieved using this A?PJ.

  3. Investigating effects of atmospheric-pressure plasma on the process of wound healing.

    PubMed

    Salehi, Shahram; Shokri, Asana; Khani, Mohammad Reza; Bigdeli, Mohammadreza; Shokri, Babak

    2015-01-01

    Cold atmospheric-pressure plasma jets (APPJ) have excellent applications in biomedicine. Advantages of APPJ include lack of need for vacuum systems, capability of operation for a long time, and safe to be directly touched by living tissues such as a human body. In this study, an APPJ was generated by a dielectric barrier and applied for the treatment of chemical wounds. This APPJ worked with argon and was driven by high-voltage pulses. This paper compares the spontaneous healing of wounds and a stimulated healing using daily APPJ treatment. Biological data, such as hematological, biochemical, and histological parameters, were remarked. The mortality and morbidity of the untreated samples were reported after 20 days in comparison with the plasma-treated samples, which were alive after these days. Experimental results demonstrated that an increase in the oxidative stress could result in the decreased destruction of lesions by controlling the infection growth. These results were related to the presence of reactive oxygen species and reactive nitrogen species in the plasma volume, which were detected by optical emission spectroscopy. PMID:25758659

  4. Atmospheric Pressure Glow Discharge for Point-of-Use Water Treatment

    NASA Astrophysics Data System (ADS)

    Lindsay, Alexander; Byrns, Brandon; Shannon, Steven; Knappe, Detlef

    2012-10-01

    Treatment of biological and chemical contaminants is an area of growing global interest where atmospheric pressure plasmas can make a significant contribution. Addressing key challenges of volume processing and operational cost, a large volume 162 MHz coaxial air-plasma source has been developed.footnotetextByrns (2012) J. Phys. D: Appl. Phys. 45 (2012) 195204 Because of VHF ballasting effects, the electric discharge is maintained at a steady glow, allowing formation of critical non-equilibrium chemistry. High densities, ne = 10^11-10^12, have been recorded. The atmospheric nature of the device permits straightforward and efficient treatment of water samples. [H^+] concentrations in 150 milliliter tap water samples have been shown to increase by 10^5 after five minutes of discharge exposure. Recent literature has demonstrated that increasing acidity is strongly correlated with a solution's ability to deactivate microbial contaminants.footnotetextTraylor (2011) J. Phys. D: Appl. Phys. 44 (2011) 472001 The work presented here will explore the impact of treatment gas, system configuration, and power density on water disinfection and PFC abatement. An array of plasma diagnostics, including OES and electrical measurements, are combined with post-process water analysis, including GC-MS and QT analysis of coliform and E.coli bacteria. Development of volume processing atmospheric plasma disinfection methods offers promise for point-of-use treatments in developing areas of the world, potentially supplementing or replacing supply and weather-dependent disinfection methods.

  5. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    NASA Technical Reports Server (NTRS)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  6. Atmospheric pressure, density, temperature and wind variations between 50 and 200 km

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Woodrum, A.

    1972-01-01

    Data on atmospheric pressure, density, temperature and winds between 50 and 200 km were collected from sources including Meteorological Rocket Network data, ROBIN falling sphere data, grenade release and pitot tube data, meteor winds, chemical release winds, satellite data, and others. These data were analyzed by a daily difference method and results on the distribution statistics, magnitude, and spatial structure of the irregular atmospheric variations are presented. Time structures of the irregular variations were determined by the analysis of residuals from harmonic analysis of time series data. The observed height variations of irregular winds and densities are found to be in accord with a theoretical relation between these two quantities. The latitude variations (at 50 - 60 km height) show an increasing trend with latitude. A possible explanation of the unusually large irregular wind magnitudes of the White Sands MRN data is given in terms of mountain wave generation by the Sierra Nevada range about 1000 km west of White Sands. An analytical method is developed which, based on an analogy of the irregular motion field with axisymmetric turbulence, allows measured or model correlation or structure functions to be used to evaluate the effective frequency spectra of scalar and vector quantities of a spacecraft moving at any speed and at any trajectory elevation angle.

  7. Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

    SciTech Connect

    Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe [Department of Molecular Science and Technology, Ajou University, San 5 Wonchon-Dong, Youngtong-Gu, Suwon 443-749 (Korea, Republic of); State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams Department of Physics, Dalian University of Technology, Dalian 116024 (China)

    2007-09-15

    A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

  8. Optimization of the mass spectrometric analysis of triacylglycerols using negative-ion chemical ionization with ammonia.

    PubMed

    Laakso, P; Kallio, H

    1996-01-01

    Conditions for the mass spectrometric analysis of triacylglycerols, via direct exposure probe, with ammonia negative-ion chemical ionization were optimized. Triacylglycerols were most favorably ionized, using the reactant gas pressure of approximately 8500 mtorr at the ion source temperature of 200 degrees C with the instrumentation used. Abundant [M-H]- ions were produced under these conditions without the formation of [M + 35]- cluster ions, which would interfere with the molecular weight region of triacylglycerols in the spectra. A rapid desorption of the sample from the probe wire is recommended, using a relatively high heating rate (approximately 40 mA s-1), to minimize thermal degradation of unsaturated molecules and the reducing effect of double bonds on the mass spectrometric response of triacylglycerols. Furthermore, the abundance of [M-H]- ion was enhanced by rapid heating, which we found to be important to improve the sensitivity. The appropriate amount of sample applied to the rhenium wire was in the region of 50-300 ng for one determination, i.e., only a few nanograms of a single triacylglycerol is required for production of a reliable spectrum. The reproducibility of the method was good as demonstrated with standards and a raspberry seed oil sample. The described mass spectrometric method is a fast and potentially useful tool for semiquantitative determination of triacylglycerol mixtures of various fats and oils. The discrimination, caused by differences in molecular size and unsaturation of triacylglycerols with 50 to 56 acyl carbons, was negligible under our optimized ionization conditions, thus, no correction factors were needed. These findings have not yet been verified with instruments in other laboratories. However, the present study shows how the analysis of triacylglycerols can be improved, regardless of the instrument, by optimization of the analytical conditions. PMID:8649231

  9. Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF4 at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Zhou, Yang; Shao, Tao; Xie, Qing; Xu, Jiayu; Yang, Wenjin

    2014-08-01

    Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF4) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF4 are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF4 flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF4 flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF4 lead to the hydrophobicity improvement of the PMMA surface after high CF4 flow rate and long time treatment. Moreover, due to the small amount of oxygen in the DBD plasma, hydrophilic effect exists on the PMMA surface after small CF4 flow rate treatment. Similar phenomenon occurs at short time treatment. It is because that sbnd CH2F, sbnd CHFsbnd , sbnd CHF2 groups, having hydrophilic property, are likely generated in the initial stage of hydrogen abstraction. In addition, because the residual groups (mainly sbnd CFsbnd , sbnd CF2sbnd and sbnd CF3) on the PMMA surface have strong hydrophobic property, the hydrophobic behavior of the treated PMMA surface could maintain for 8-day aging period.

  10. [Application of atomic emission spectroscopy analysis in the atmospheric pressure plasma polishing process study].

    PubMed

    Wang, Bo; Zhang, Ju-Fan; Dong, Shen

    2008-07-01

    The atmospheric pressure plasma polishing (APPP) is a novel precision machining technology. It performs the atom scale material removal based on low temperature plasma chemical reactions. As the machining process is chemical in nature, it avoids the surface/subsurface defects usually formed in conventional mechanical machining processes. APPP firstly introduces a capacitance coupled radio frequency (RF) plasma torch to generate reactive plasma and excite chemical reactions further. The removal process is a complicated integrating action which tends to be affected by many factors, such as the gas ratio, the RF power and so on. Therefore, to improve the machining quality, all the aspects should be considered and studied, to establish the foundation for further model building and theoretical analysis. The atomic emission spectroscopy analysis was used to study the process characteristics. A commercial micro spectrometer was used to collect the spectrograms under different parameters, by comparing which the influence of the RF power and gas ratio was initially studied. The analysis results indicate that an increase in RF power results in a higher removal rate within a certain range. The gas ratio doesn't show obvious influence on the removal rate and surface roughness in initial experiments, but the element compositions detected by X-ray photoelectron spectroscopy technology on the machined surfaces under different ratios really indicate distinct difference. Then the theoretical analysis revealed the corresponding electron transition orbits of the excited reactive fluorine atoms, which is necessary for further mechanism research and apparatus improvement. Then the initial process optimization was made based on the analysis results, by which the Ra 0.6 nm surface roughness and 32 mm3 x min(-1) removal rate were achieved on silicon wafers. PMID:18844179

  11. Picoelectrospray Ionization Mass Spectrometry Using Narrow-bore Chemically Etched Emitters

    SciTech Connect

    Marginean, Ioan; Tang, Keqi; Smith, Richard D.; Kelly, Ryan T.

    2014-01-01

    Electrospray ionization mass spectrometry (ESI-MS) at flow rates below ~10 nL/min has been only sporadically explored due to difficulty in reproducibly fabricating emitters that can operate at lower flow rates. Here we demonstrate narrow orifice chemically etched emitters for stable electrospray at flow rates as low as 400 pL/min. Depending on the analyte concentration, we observe two types of MS signal response as a function of flow rate. At low concentrations, an optimum flow rate is observed slightly above 1 nL/min, while the signal decreases monotonically with decreasing flow rates at higher concentrations. In spite of lower MS signal, the ion utilization efficiency increases exponentially with decreasing flow rate in all cases. No unimolecular response was observed within this flow rate range during the analysis of an equimolar mixture of peptides, indicating that ionization efficiency is an analyte-dependent characteristic in given experimental conditions. While little to no gain in signal-to-noise was achieved at ultralow flow rates for concentration-limited analyses, experiments consuming the same amount of analyte suggest that mass-limited analyses will benefit strongly from the use of low flow rates and avoiding unnecessary sample dilution. By operating under optimal conditions, consumption of just 500 zmol of sample yielded signal-to-noise ratios ~10 for some peptides. These findings have important implications for the analysis of trace biological samples.

  12. Characterization of aromatized biomarkers by GC/MS/MS with chemical ionization

    SciTech Connect

    Hsu, C.S.; Dechert, G.J. [Exxon Research and Engineering Co., Annandale, NJ (United States); Schaps, M.E.; Hieshima, G.B. [Exxon Production Research Co., Houston, TX (United States)

    1995-12-31

    Although present in trace amounts, biomarkers are extensively studied by geochemists to understand paleotransformation processes that convert ancient living organisms into petroleum components and to assess age, maturity and source input of the petroleum. Most studied are saturated biomarkers that yield both molecular and characteristic fragment ions under high voltage (50-70 V) electron-impact ionization (HV/EI) conditions. Linking these molecular and fragment ions derived from saturated hydrocarbon compounds using GC/MS/MS resolves coeluting components and provides less ambiguous geochemical information than GC/MS. The same GC/MS/MS techniques cannot be applied to aromatized biomarkers because they yield trace or no molecular ions under HV/EI conditions. To overcome these difficulties, chemical ionization (CI) has been studied for producing ionic species more representative of molecules. Among the reagent gases evaluated, isobutane yields predominantly protonated molecular ions while methane and ammonia yield more than one type of pseudomolecular ions. Thus, isobutane is the gas of choice for the aromatic biomarkers using GC/MS/MS with CI. This analytical technique is particularly useful for resolving overlapping monoaromatic steranes (MAS). Characterization of aromatic biomarkers more accurately would help to explain better the maturation mechanism of petroleum molecules under thermal stress.

  13. Ion/molecule reactions to chemically deconvolute the electrospray ionization mass spectra of synthetic polymers.

    PubMed

    Lennon, John D; Cole, Scott P; Glish, Gary L

    2006-12-15

    A new approach has been developed to analyze synthetic polymers via electrospray ionization mass spectrometry. Ion/molecule reactions, a unique feature of trapping instruments such as quadrupole ion trap mass spectrometers, can be used to chemically deconvolute the molecular mass distribution of polymers from the charge-state distribution generated by electrospray ionization. The reaction involves stripping charge from multiply charged oligomers to reduce the number of charge states. This reduces or eliminates the overlapping of oligomers from adjacent charge states. 15-Crown-5 was used to strip alkali cations (Na+) from several narrow polydisperse poly(ethylene glycol) standards. The charge-state distribution of each oligomer is reduced to primarily one charge state. Individual oligomers can be resolved, and the average molecular mass and polydispersities can be calculated for the polymers examined here. In most cases, the measured number-average molecular mass values are within 10% of the manufacturers' reported values obtained by gel permeation chromatography. The polydispersity was typically underestimated compared to values reported by the suppliers. Mn values were obtained with 0.5% RSD and are independent, over several orders of magnitude, of the polymer and cation concentration. The distributions that were obtained fit quite well to the Gaussian distribution indicating no high- or low-mass discriminations. PMID:17165841

  14. A chemical ionization selected ion monitoring assay for methylphenidate and ritalinic acid.

    PubMed

    Iden, C R; Hungund, B L

    1979-10-01

    A methane chemical ionization quantitative assay for methylphenidate and its major metabolite, ritalinic acid, is described. Methylphenidate and the internal standard, ethylphenidate, were extracted from plasma samples and derivatized to prevent thermal decomposition in the gas chromatography. Ritalinic acid was esterified with diazomethane and extracted as methylphenidate. The intensity of the protonated molecular ion of the derivatized drug and internal standard was measured by selected ion monitoring. Calibration curves were prepared from drug standards dissolved in drug-free plasma, and the lower limit of the curves extended to 0.5 ng methylphenidate per ml plasma. The method was used to generate plasma decay curves for pediatric patients undergoing methylphenidate therapy. PMID:526558

  15. Water chemical ionization mass spectrometry of aldehydes, ketones esters, and carboxylic acids

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.

    1986-11-01

    Chemical ionization mass spectrometry (CI) of aliphatic and aromatic carbonyl compounds using water as the reagent gas provides intense pseudomolecular ions and class-specific fragmentation patterns that can be used to identify aliphatic aldehydes, ketones, carboxylic acids, and esters. The length of ester acyl and alkyl groups can easily be determined on the basis of loss of alcohols from the protonated parent. Water CI provides for an approximately 200:1 selectivity of carbonyl species over alkanes. No reagent ions are detected above 55 amu, allowing species as small as acetone, propanal, acetic acid, and methyl formate to be identified. When deuterate water was used as the reagent, only the carboxylic acids and ..beta..-diketones showed significant H/D exchange. The use of water CI to identify carbonyl compounds in a wastewater from the supercritical water extraction of lignite coal, in lemon oil, and in whiskey volatiles is discussed.

  16. Gas chromatography plasma-assisted reaction chemical ionization mass spectrometry for quantitative detection of bromine in organic compounds.

    PubMed

    Lin, Ninghang; Wang, Haopeng; Kahen, Kaveh; Badiei, Hamid; Jorabchi, Kaveh

    2014-08-01

    We have recently introduced plasma-assisted reaction chemical ionization mass spectrometry (PARCI-MS) for elemental analysis of halogens in organic compounds. Here, we utilize gas chromatography (GC) coupled to PARCI-MS to investigate the mechanism of Br(-) ion generation from organobromines and to evaluate analytical performance of PARCI for organobromine analysis. Bromine atoms in compounds eluting from GC are converted to HBr in a low-pressure microwave induced helium plasma with trace amounts of hydrogen added as a reaction gas. Ionization is achieved by introducing nitrogen into the afterglow region of the plasma, liberating electrons via penning ionization and leading to formation of negative ions. We demonstrate that N2 largely affects the ionization process, whereas H2 affects both the ionization process and in-plasma reactions. Our investigations also suggest that dissociative electron capture is the main ionization route for formation of Br(-) ions. Importantly, GC-PARCI-MS shows a uniform response factor for bromine across brominated compounds of drastically different chemical structures, confirming PARCI's ability to quantify organobromines in the absence of compound-specific standards. Over 3 orders of magnitude linear dynamic range is demonstrated for bromine quantification. We report a detection limit of 29 fg of bromine on-column, ~4-fold better than inductively coupled plasma-MS. PMID:25003497

  17. Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)

    NASA Astrophysics Data System (ADS)

    You, Y.; Kanawade, V. P.; de Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S.-H.

    2014-11-01

    We report measurements of ambient amines and ammonia with a fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest and a moderately polluted midwestern site during the summer. At the forest site, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected, and they both showed temperature dependencies. Aerosol-phase amines measured thermal-desorption chemical ionization mass spectrometer (TDCIMS) showed a higher mass fraction in the evening with cooler temperatures and lower in the afternoon with warmer temperatures, a trend opposite to the gas-phase amines. Concentrations of aerosol-phase primary amines measured with Fourier transform infrared spectroscopy (FTIR) from micron and submicron particles were 2 orders of magnitude higher than the gas-phase amines. These results indicate that gas to particle conversion is one of the major processes that control the ambient amine concentrations at this forest site. Temperature dependencies of C3-amines and ammonia also imply reversible processes of evaporation of these nitrogen-containing compounds from soil surfaces in daytime and deposition to soil surfaces at nighttime. During the transported biomass burning plume events, various amines (C1-C6) appeared at the pptv level, indicating that biomass burning is a substantial source of amines in the southeastern US. At the moderately polluted Kent site, there were higher concentrations of C1- to C6-amines (pptv to tens of pptv) and ammonia (up to 6 ppbv). C1- to C3-amines and ammonia were well correlated with the ambient temperature. C4- to C6-amines showed frequent spikes during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Higher amine concentrations measured at the polluted site than at the rural forested site highlight the importance of constraining anthropogenic emission sources of amines.

  18. Experimental and numerical study of an atmospheric pressure glow discharge in helium

    NASA Astrophysics Data System (ADS)

    Mangolini, Lorenzo; Zhang, Peng; Anderson, Curtis; Kortshagen, Uwe; Heberlein, Joachim

    2002-10-01

    . Atmospheric pressure glow discharges in helium have been reported to produce radially uniform plasmas and to show one single current pulse per half cycle of the AC high voltage [1]. However, in other studies the appearance of multiple periodic peaks per half cycle has been reported as well. Different interpretations have been given for this effect ranging from the oscillation of the cathode sheath [2] to multiple successive breakdowns [3]. We have performed studies with different dielectrics to investigate their effect on the discharge behavior: two circular 4 cm diameter electrodes have been covered with (1) 1.7 mm thick glass plates (er = 4.6) and with (2) 0.635 mm thick alumina plates (er = 9). At a gap of 5 mm, multiple current peaks were observed with both configurations. Time resolved measurements of the emission intensity using a gated intensified CCD camera were performed, both in axial and radial direction. These indicate that the first current pulse is produced by a radially propagating ionization front, while later peaks are related to breakdowns at the electrode edges. With 0.635 mm thick alumina plates we could observe the appearance of a strong cathode fall in front of the momentary cathode, together with a Faraday dark space and a positive column that extended for a length of 2-3 mm. A two-dimensional fluid model has been realized to study the glow discharge behavior. The numerical result is qualitatively in good agreement with the observed structure of the discharge. The model reproduces the radial propagation of the ionization wave. This work is supported by the Department of Energy under grant DE-FG02-00ER54583. [1] Massines F., Rabehi A., Decomps P., Gadri R.B., Segur P., and Mayoux C., J.Appl.Phys. 83, 2950- 2957 (1998). [2] Akishev Y.S., Dem'yanov A., Karal'nik V.B., Trushkin N.I., and Pan'kin M.V., Proc. Of XXIV ICPIG, Poland, July 11-16, 137-138, (1999). [3] Mangolini L., Orlov K., Kortshagen U., Heberlein J., and Kogelschatz U., Appl.Phys.Lett.80, 1723 (2002).

  19. On the use of pulsed Dielectric Barrier Discharges to control the gas-phase composition of atmospheric pressure air plasmas

    NASA Astrophysics Data System (ADS)

    Barni, R.; Biganzoli, I.; Dell'Orto, E.; Riccardi, C.

    2014-11-01

    We presents results obtained from the numerical simulation of the gas-phase chemical kinetics in atmospheric pressure air non-equilibrium plasmas. In particular we have addressed the effect of pulsed operation mode of a plane dielectric barrier discharge. It was conjectured that the large difference in the time scales involved in the fast dissociation of oxygen molecules in plasma and their subsequent reactions to produce ozone and nitrogen oxides, makes the presence of a continuously repeated plasma production unnecessary and a waste of electrical power and thus efficiency. In order to test such suggestion we have performed a numerical study of the composition and the temporal evolution of the gas-phase of atmospheric pressure air non-equilibrium plasmas. Comparison with experimental findings in a dielectric barrier discharge with an electrode configuration symmetrical and almost ideally plane is briefly addressed too, using plasma diagnostics to extract the properties of the single micro-discharges and a sensor to measure the concentration of ozone produced by the plasma.

  20. Atmospheric sampling glow discharge ionization source

    DOEpatents

    McLuckey, S.A.; Glish, G.L.

    1989-07-18

    An atmospheric sampling glow discharge ionization source that can be used in combination with an analytical instrument which operates at high vacuum, such as a mass spectrometer. The atmospheric sampling glow discharge ionization source comprises a chamber with at least one pair of electrodes disposed therein, an inlet for a gaseous sample to be analyzed and an outlet communicating with an analyzer which operates at subatmospheric pressure. The ionization chamber is maintained at a pressure below atmospheric pressure, and a voltage difference is applied across the electrodes to induce a glow discharge between the electrodes, so that molecules passing through the inlet are ionized by the glow discharge and directed into the analyzer. The ionization source accepts the sample under atmospheric pressure conditions and processes it directly into the high vacuum instrument, bridging the pressure gap and drawing off unwanted atmospheric gases. The invention also includes a method for analyzing a gaseous sample using the glow discharge ionization source described above. 3 figs.