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Sample records for gas chromatography-electron ionization

  1. Evaluation of gas chromatography - electron ionization - full scan high resolution Orbitrap mass spectrometry for pesticide residue analysis.

    PubMed

    Mol, Hans G J; Tienstra, Marc; Zomer, Paul

    2016-09-01

    Gas chromatography with electron ionization and full scan high resolution mass spectrometry with an Orbitrap mass analyzer (GC-EI-full scan Orbitrap HRMS) was evaluated for residue analysis. Pesticides in fruit and vegetables were taken as an example application. The relevant aspects for GC-MS based residue analysis, including the resolving power (15,000 to 120,000 FWHM at m/z 200), scan rate, dynamic range, selectivity, sensitivity, analyte identification, and utility of existing EI-libraries, are assessed and discussed in detail. The optimum acquisition conditions in full scan mode (m/z 50-500) were a resolving power of 60,000 and an automatic-gain-control target value of 3E6. These conditions provided (i) an optimum mass accuracy: within 2 ppm over a wide concentration range, with/without matrix, enabling the use of ±5 ppm mass extraction windows (ii) adequate scan speed: minimum 12 scans/peak, (iii) an intra-scan dynamic range sufficient to achieve LOD/LOQs ≤0.5 pg in fruit/vegetable matrices (corresponding to ≤0.5 μg kg(-1)) for most pesticides. EI-Orbitrap spectra were consistent over a very wide concentration range (5 orders) with good match values against NIST (EI-quadrupole) spectra. The applicability for quantitative residue analysis was verified by validation of 54 pesticides in three matrices (tomato, leek, orange) at 10 and 50 μg/kg. The method involved a QuEChERS-based extraction with a solvent switch into iso-octane, and 1 μL hot splitless injection into the GC-HRMS system. A recovery between 70 and 120% and a repeatability RSD <10% was obtained in most cases. Linearity was demonstrated for the range ≤5-250 μg kg(-1). The pesticides could be identified according to the applicable EU criteria for GC-HRMS (SANTE/11945/2015). GC-EI-full scan Orbitrap HRMS was found to be highly suited for quantitative pesticide residue analysis. The potential of qualitative screening to extend the scope makes it an attractive alternative to GC

  2. 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".

  3. Rapid direct analysis to discriminate geographic origin of extra virgin olive oils by flash gas chromatography electronic nose and chemometrics.

    PubMed

    Melucci, Dora; Bendini, Alessandra; Tesini, Federica; Barbieri, Sara; Zappi, Alessandro; Vichi, Stefania; Conte, Lanfranco; Gallina Toschi, Tullia

    2016-08-01

    At present, the geographical origin of extra virgin olive oils can be ensured by documented traceability, although chemical analysis may add information that is useful for possible confirmation. This preliminary study investigated the effectiveness of flash gas chromatography electronic nose and multivariate data analysis to perform rapid screening of commercial extra virgin olive oils characterized by a different geographical origin declared in the label. A comparison with solid phase micro extraction coupled to gas chromatography mass spectrometry was also performed. The new method is suitable to verify the geographic origin of extra virgin olive oils based on principal components analysis and discriminant analysis applied to the volatile profile of the headspace as a fingerprint. The selected variables were suitable in discriminating between "100% Italian" and "non-100% Italian" oils. Partial least squares discriminant analysis also allowed prediction of the degree of membership of unknown samples to the classes examined. PMID:26988501

  4. Rapid direct analysis to discriminate geographic origin of extra virgin olive oils by flash gas chromatography electronic nose and chemometrics.

    PubMed

    Melucci, Dora; Bendini, Alessandra; Tesini, Federica; Barbieri, Sara; Zappi, Alessandro; Vichi, Stefania; Conte, Lanfranco; Gallina Toschi, Tullia

    2016-08-01

    At present, the geographical origin of extra virgin olive oils can be ensured by documented traceability, although chemical analysis may add information that is useful for possible confirmation. This preliminary study investigated the effectiveness of flash gas chromatography electronic nose and multivariate data analysis to perform rapid screening of commercial extra virgin olive oils characterized by a different geographical origin declared in the label. A comparison with solid phase micro extraction coupled to gas chromatography mass spectrometry was also performed. The new method is suitable to verify the geographic origin of extra virgin olive oils based on principal components analysis and discriminant analysis applied to the volatile profile of the headspace as a fingerprint. The selected variables were suitable in discriminating between "100% Italian" and "non-100% Italian" oils. Partial least squares discriminant analysis also allowed prediction of the degree of membership of unknown samples to the classes examined.

  5. Diffuse, Warm Ionized Gas

    NASA Astrophysics Data System (ADS)

    Haffner, L. M.

    2002-05-01

    Over the past decade, new high-sensitivity observations have significantly advanced our knowledge of the diffuse, ionized gas in spiral galaxies. This component of the interstellar medium, often referred to as Warm Ionized Medium (WIM) or Diffuse Ionized Gas (DIG), plays an important role in the complex stellar-interstellar matter and energy cycle. In examining the distribution and physical properties of this gas, we learn not only about the conditions of the medium but also about processes providing heating and ionization in the halos of spiral galaxies. For the Milky Way, three new Hα surveys are available providing large sky coverage, arc-minute spatial resolution, and the ability to kinematically resolve this prominent optical emission line. These new, global views show that the Warm Ionized Medium of the Galaxy is ubiquitous as previously suspected, is rich with filamentary structure down to current resolution limits, and can be traced into the halo at large distances from the Galactic plane. Observations of additional optical emission lines are beginning to probe the physical conditions of the WIM. Early results suggest variations in the temperature and ionization state of the gas which are not adequately explained by Lyman continuum stellar photoionization alone. In parallel with this intensive work in the Milky Way have been numerous studies about the diffuse, ionized gas in other spiral galaxies. Here, deep, face-on spiral investigations provide some of the best maps of the global DIG distribution in a galaxy and begin to allow a probe of the local link between star formation and the powering of ionized gas. In addition, ionized gas has been traced out to impressive distances (z > 3 kpc) in edge-on spirals, revealing out large-scale changes in the physical conditions and kinematics of galactic halos.

  6. Performance characteristics of an analytical procedure for determining chloramphenicol residues in muscle tissue by gas chromatography-electron capture detection.

    PubMed

    Cerkvenik-Flajs, Vesna

    2006-10-01

    Validation of an analytical method for determining chloramphenicol residues in muscle tissue by gas chromatography-electron capture detection (GC-ECD) was performed according to the latest European Union criteria for the analysis of veterinary drugs in food, laid down by Commission Decision 2002/657/EC. The method using the meta isomer of chloramphenicol as an internal standard proved to be very selective, specific to other related phenicols and accurate to within +3.6% at a concentration level of 8.9 microg/kg, as present in the certified reference material available. The correlation coefficient of the calibration curve was 0.9991. At all three fortification levels studied (0.3, 0.45 and 0.6 microg/kg), repeatability and intra-laboratory reproducibility were <8 and < or =9%, respectively. The decision limit (CCalpha) and detection capability (CCbeta) were 0.07 and 0.12 microg/kg, respectively. The validation results and the results of participation in an international inter-laboratory proficiency test indicate that the method presented is completely suited for regulatory control to screen and quantify chloramphenicol residues in various muscle tissues on a routine basis.

  7. Quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector.

    PubMed

    Field, Christopher R; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C; Rose-Pehrsson, Susan L

    2014-07-25

    The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

  8. Quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector.

    PubMed

    Field, Christopher R; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C; Rose-Pehrsson, Susan L

    2014-01-01

    The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples. PMID:25145416

  9. Boosting the Detection Potential of Liquid Chromatography-Electron Ionization Mass Spectrometry Using a Ceramic Coated Ion Source

    NASA Astrophysics Data System (ADS)

    Magrini, Laura; Famiglini, Giorgio; Palma, Pierangela; Termopoli, Veronica; Cappiello, Achille

    2016-01-01

    Detection of target and non-target substances and their characterization in complex samples is a challenging task. Here we demonstrate that coating the electron ionization (EI) ion source of an LC-MS system with a sol-gel ceramic film can drastically improve the detection of high-molecular weight and high-boiling analytes. A new ion source coated with a ceramic material was developed and tested with a mixture of polycyclic aromatic hydrocarbons (PAH) with an increasing number of rings. Comparison of the results obtained with those for an uncoated stainless steel (SS) ion source shows a dramatic improvement in the MS signals, with a nearly 40-fold increase of the signal-to-noise ratio. We also demonstrate the ability of the new system to produce excellent chromatographic profiles for hard-to-detect hormones.

  10. A novel high-performance liquid chromatography-electron spray ionization-mass spectrometry method for simultaneous determination of guggulsterones, piperine and gallic acid in Triphala guggulu.

    PubMed

    Muguli, Ganesh; Vadaparthi, P R Rao; Ramesh, B; Gowda, Vishakante; Paramesh, Rangesh; Jadhav, Atul N; Babu, K Suresh

    2015-05-01

    "Triphalaguggulu" is an important Ayurvedic formulation comprising of Guggulu, that is, Commiphora wightii (Arn.) Bhandari as a base wherein powdered fruits of triphala, that is, Phyllanthus emblica L., Terminalia bellirica (Gaertn.) Roxb and Terminalia chebula Retz, along with powdered fruit of Piper longum L. are compounded. This polyherbal preparation has been strongly recommended in chronic inflammation, piles, and fistula. However, due to the complexity of compound formulation standardization of commercial products is challenging. In the present communication marker-based standardization of "Triphalaguggulu" preparation using gallic acid (for triphala), piperine (for P. longum L.) and guggulsterones (for guggulu) is reported. These compounds of diverse chemistry were successfully separated on a Waters HR-C18 column by isocratic elution with methanol and water (80:20 v/v) as mobile phase at the flow rate of 1.0 mL/min coupled with photodiode array detector. These optimal chromatographic conditions were used for simultaneous quantification of gallic acid, guggulsterones (E and Z) and piperine in commercial samples by high-performance liquid chromatography-electron spray ionization-mass spectrometry and method was validated as per ICH guidelines. PMID:26109777

  11. A novel high-performance liquid chromatography-electron spray ionization-mass spectrometry method for simultaneous determination of guggulsterones, piperine and gallic acid in Triphala guggulu

    PubMed Central

    Muguli, Ganesh; Vadaparthi, P. R. Rao; Ramesh, B.; Gowda, Vishakante; Paramesh, Rangesh; Jadhav, Atul N.; Babu, K. Suresh

    2015-01-01

    “Triphalaguggulu” is an important Ayurvedic formulation comprising of Guggulu, that is, Commiphora wightii (Arn.) Bhandari as a base wherein powdered fruits of triphala, that is, Phyllanthus emblica L., Terminalia bellirica (Gaertn.) Roxb and Terminalia chebula Retz, along with powdered fruit of Piper longum L. are compounded. This polyherbal preparation has been strongly recommended in chronic inflammation, piles, and fistula. However, due to the complexity of compound formulation standardization of commercial products is challenging. In the present communication marker-based standardization of “Triphalaguggulu” preparation using gallic acid (for triphala), piperine (for P. longum L.) and guggulsterones (for guggulu) is reported. These compounds of diverse chemistry were successfully separated on a Waters HR-C18 column by isocratic elution with methanol and water (80:20 v/v) as mobile phase at the flow rate of 1.0 mL/min coupled with photodiode array detector. These optimal chromatographic conditions were used for simultaneous quantification of gallic acid, guggulsterones (E and Z) and piperine in commercial samples by high-performance liquid chromatography-electron spray ionization-mass spectrometry and method was validated as per ICH guidelines. PMID:26109777

  12. Trace analysis of trichlorobenzenes in fish by microwave-assisted extraction and gas chromatography-electron-capture detection.

    PubMed

    Wittmann, Gyula; Huybrechts, Tom; Van Langenhove, Herman; Dewulf, Jo; Nollet, Hendrik

    2003-04-18

    An analytical method consisting of extraction, clean-up, and analysis by gas chromatography-electron-capture detection (GC-ECD) was developed for the determination of trichlorobenzenes (TCBs) in fish samples. Two extraction methods, saponification and liquid-liquid extraction (S-LLE), and microwave-assisted extraction (MAE), were evaluated. In both cases, n-pentane was used as the extraction solvent. For S-LLE, the recoveries ranged from 66.6+/-9.1% for 1-bromo-4-chlorobenzene (4-BCB) to 93.5+/-4.9% for 1,2,4-trichlorobenzene (1,2,4-TCB). The recoveries were significantly lower, between 31.0+/-3.9% for 1,2,3-trichlorobenzene (1,2,3-TCB) and 52.3+/-3.0% for 1,3,5-trichlorobenzene (1,3,5-TCB), in the absence of fish. Proteins and glycerides of the fish tissue seemed to compete with TCBs for the base, and hence decreased their decomposition rate. In the case of MAE, the recoveries were highly dependent on the pressure applied during extraction. At 5 bar, much higher recoveries were obtained, from 66.7+/-15.6% for 4-BCB to 79.9+/-13.6% for 1,2,4-TCB, than at 1 bar. Sulfur formation was, however, observed at 5 bar, and interfered with the GC-ECD analysis of TCBs. Sulfur was adequately removed by copper powder treatment, which was shown not to affect the recovery of analytes. The recoveries of target analytes by S-LLE and MAE did not differ statistically (t-test, alpha = 0.01). Both methods were appropriate for the detection of TCBs at concentration levels typically observed in marine biota, i.e. approximately 1 ng/g. S-LLE was, however, more time consuming, and required larger volumes of high-purity organic solvents than MAE.

  13. Gas amplified ionization detector for gas chromatography

    DOEpatents

    Huston, Gregg C.

    1992-01-01

    A gas-amplified ionization detector for gas chromatrography which possesses increased sensitivity and a very fast response time. Solutes eluding from a gas chromatographic column are ionized by UV photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the UV photoionization of at least a portion of each solute passing through the detector.

  14. Measurement of polychlorinated biphenyls in solid waste such as transformer insulation paper by supercritical fluid extraction and gas chromatography electron capture detection.

    PubMed

    Chikushi, Hiroaki; Fujii, Yuka; Toda, Kei

    2012-09-21

    In this work, a method for measuring polychlorinated biphenyls (PCBs) in contaminated solid waste was investigated. This waste includes paper that is used in electric transformers to insulate electric components. The PCBs in paper sample were extracted by supercritical fluid extraction and analyzed by gas chromatography-electron capture detection. The recoveries with this method (84-101%) were much higher than those with conventional water extraction (0.08-14%), and were comparable to those with conventional organic solvent extraction. Limit of detection was 0.0074 mg kg(-1) and measurable up to 2.5 mg kg(-1) for 0.5 g of paper sample. Data for real insulation paper by the proposed method agreed well with those by the conventional organic solvent extraction. Extraction from wood and concrete was also investigated and good performance was obtained as well as for paper samples. The supercritical fluid extraction is simpler, faster, and greener than conventional organic solvent extraction.

  15. Simultaneous analysis of polychlorinated biphenyls and organochlorine pesticides in seawater samples by membrane-assisted solvent extraction combined with gas chromatography-electron capture detector and gas chromatography-tandem mass spectrometry.

    PubMed

    Shi, Xizhi; Tang, Zigang; Sun, Aili; Zhou, Lei; Zhao, Jian; Li, Dexiang; Chen, Jiong; Pan, Daodong

    2014-12-01

    A highly efficient and environment-friendly membrane-assisted solvent extraction system combined with gas chromatography-electron capture detector was applied in the simultaneous determination of 17 polychlorinated biphenyls and organochlorine pesticides in seawater samples. Variables affecting extraction efficiency, including extraction solvent used, stirring rate, extraction time, and temperature, were optimized extensively. Under optimal extraction conditions, recoveries between 76.9% and 104.6% in seawater samples were achieved, and relative standard deviation values below 10% were obtained. The limit of detection (signal-to-noise ratio=3) and limit of quantification (signal-to-noise ratio=10) of 17 polychlorinated biphenyls and organochlorine pesticides in seawater ranged from 0.14ngL(-1) to 0.36ngL(-1) and 0.46ngL(-1) to 1.19ngL(-1), respectively. Matrix effects on extraction efficiency were evaluated by comparing with the results obtained using tap water. The extraction effect of developed membrane-assisted solvent extraction method was further demonstrated by gas chromatography-tandem mass spectrometry which can provide structural information of the analytes for more accurate identification, and results identical to those produced by gas chromatography-electron capture detector were obtained. These findings demonstrate the applicability of the developed membrane-assisted solvent extraction determination method for coupling to gas chromatography-electron capture detector or tandem mass spectrometry for determining polychlorinated biphenyls and organochlorine pesticides in seawater samples.

  16. Simultaneous analysis of polychlorinated biphenyls and organochlorine pesticides in seawater samples by membrane-assisted solvent extraction combined with gas chromatography-electron capture detector and gas chromatography-tandem mass spectrometry.

    PubMed

    Shi, Xizhi; Tang, Zigang; Sun, Aili; Zhou, Lei; Zhao, Jian; Li, Dexiang; Chen, Jiong; Pan, Daodong

    2014-12-01

    A highly efficient and environment-friendly membrane-assisted solvent extraction system combined with gas chromatography-electron capture detector was applied in the simultaneous determination of 17 polychlorinated biphenyls and organochlorine pesticides in seawater samples. Variables affecting extraction efficiency, including extraction solvent used, stirring rate, extraction time, and temperature, were optimized extensively. Under optimal extraction conditions, recoveries between 76.9% and 104.6% in seawater samples were achieved, and relative standard deviation values below 10% were obtained. The limit of detection (signal-to-noise ratio=3) and limit of quantification (signal-to-noise ratio=10) of 17 polychlorinated biphenyls and organochlorine pesticides in seawater ranged from 0.14ngL(-1) to 0.36ngL(-1) and 0.46ngL(-1) to 1.19ngL(-1), respectively. Matrix effects on extraction efficiency were evaluated by comparing with the results obtained using tap water. The extraction effect of developed membrane-assisted solvent extraction method was further demonstrated by gas chromatography-tandem mass spectrometry which can provide structural information of the analytes for more accurate identification, and results identical to those produced by gas chromatography-electron capture detector were obtained. These findings demonstrate the applicability of the developed membrane-assisted solvent extraction determination method for coupling to gas chromatography-electron capture detector or tandem mass spectrometry for determining polychlorinated biphenyls and organochlorine pesticides in seawater samples. PMID:25310709

  17. Ionization-based detectors for gas chromatography.

    PubMed

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. PMID:25757823

  18. Ionization-based detectors for gas chromatography.

    PubMed

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report.

  19. Solid phase extraction with silicon dioxide microsphere adsorbents in combination with gas chromatography-electron capture detection for the determination of DDT and its metabolites in water samples.

    PubMed

    Zhou, Qingxiang; Wu, Wei; Xie, Guohong

    2013-01-01

    The goal of the present study was to investigate the feasibility of silicon dioxide (SiO(2)) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-dichlorodiphenyl-2,2-dichloroethylene (p,p'-DDD) and p,p'-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2-30 ng mL(-1) and the correlation coefficients were in the range of 99.96-99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT, and p,p'-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4-112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment. PMID:23356340

  20. Group-selective enrichment and determination of pyrethroid insecticides in aquaculture seawater via molecularly imprinted solid phase extraction coupled with gas chromatography-electron capture detection.

    PubMed

    Shi, Xizhi; Liu, Jinghua; Sun, Aili; Li, Dexiang; Chen, Jiong

    2012-03-01

    Two types of molecularly imprinted polymers (MIPs) for the simultaneous determination of six pyrethroid insecticides have been developed using deltamethrin (D-MIPs) and cypermethrin (C-MIPs) as template molecules. A comparison of the performance of D-MIPs, C-MIPs, and the corresponding non-imprinted polymers (NIPs) were conducted. Stronger group-selective interactions between the C-MIPs and the six pyrethroid insecticides were achieved. The MISPE method based on the C-MIPs displayed higher extraction recoveries (86.4-96.0%) with RSD values ranging from 2.4 to 7.8% for the six pyrethroid insecticides in aquaculture seawater. After the C-MIP cartridge procedure, the limits of detection and quantification for fenvalerate, deltamethrin, cypermethrin, cyfluthrin, and bifenthrin were in the 16.6-37.0 and 55.3-109.1 ng L⁻¹ ranges, respectively, and 0.68 and 2.26 μg L⁻¹ for phenothrin, respectively. The proposed MISPE method coupled with gas chromatography-electron capture detection was successfully used for the determination of the six pyrethroid insecticides in aquaculture seawater.

  1. Solid phase extraction with silicon dioxide microsphere adsorbents in combination with gas chromatography-electron capture detection for the determination of DDT and its metabolites in water samples.

    PubMed

    Zhou, Qingxiang; Wu, Wei; Xie, Guohong

    2013-01-01

    The goal of the present study was to investigate the feasibility of silicon dioxide (SiO(2)) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-dichlorodiphenyl-2,2-dichloroethylene (p,p'-DDD) and p,p'-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2-30 ng mL(-1) and the correlation coefficients were in the range of 99.96-99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L(-1) for p,p'-DDD, p,p'-DDT, o,p'-DDT, and p,p'-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4-112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment.

  2. [Analysis of organochlorine pesticides and pyrethroid pesticides in vegetables by gas chromatography-electron capture detection coupled with solid-phase extraction using multiwalled carbon nanotubes as adsorbent].

    PubMed

    Zhao, Haixiang; Jia, Yanxia; Ding, Mingyu; Sun, Dajiang; Zhao, Mengbin

    2011-05-01

    A multi-residue analytical method based on solid-phase extraction (SPE) with multiwalled carbon nanotubes (MWCNTs) as adsorbent was developed. The determination of 6 organochlorine pesticides and 7 pyrethroid pesticides in vegetables (including cucumber, cherry tomato, cabbage, lettuce, purple cabbage, leek, shallot and onion) was carried out by gas chromatography-electron capture detection (GC-ECD). The GC-ECD method used two columns (HP-50 and HP-1) and two ECD detectors. The HP-50 column was used for the analysis and the HP-1 column for validation. The clean-up conditions were optimized. The analytes were extracted by acetonitrile, and the extract was cleaned up by the MWCNTs SPE cartridge. The extract was re-dissolved by hexane, eluted with acetone-hexane (7:3, v/v) from the columns. The recoveries were over 70% for the 11 pesticides in the 13 pesticides. The results indicated that the MWCNTs SPE cartridge was efficient for 8 vegetable samples, because it reduced the contamination of the coloring materials to GC-ECD. The experimental results showed the MWCNTs SPE cartridge can adsorb the coloring materials and the eluant was nearly colorless.

  3. Determination of acetanilide herbicides in cereal crops using accelerated solvent extraction, solid-phase extraction and gas chromatography-electron capture detector.

    PubMed

    Zhang, Yaping; Yang, Jun; Shi, Ronghua; Su, Qingde; Yao, Li; Li, Panpan

    2011-07-01

    A method was developed to determine eight acetanilide herbicides from cereal crops based on accelerated solvent extraction (ASE) and solid-phase extraction (SPE) followed by gas chromatography-electron capture detector (GC-ECD) analysis. During the ASE process, the effect of four parameters (temperature, static time, static cycles and solvent) on the extraction efficiency was considered and compared with shake-flask extraction method. After extraction with ASE, four SPE tubes (graphitic carbon black/primary secondary amine (GCB/PSA), GCB, Florisil and alumina-N) were assayed for comparison to obtain the best clean-up efficiency. The results show that GCB/PSA cartridge gave the best recoveries and cleanest chromatograms. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision and recovery were studied. At 0.05 mg/kg spiked level, recoveries and precision values for rice, wheat and maize were 82.3-115.8 and 1.1-13.6%, respectively. For all the herbicides, LOD and LOQ ranged from 0.8 to 1.7 μg/kg and from 2.4 to 5.3 μg/kg, respectively. The proposed analytical methodology was applied for the analysis of the targets in samples; only three herbicides, propyzamid, metolachlor and diflufenican, were detected in two samples. PMID:21656677

  4. [Analysis of organochlorine pesticides and pyrethroid pesticides in vegetables by gas chromatography-electron capture detection coupled with solid-phase extraction using multiwalled carbon nanotubes as adsorbent].

    PubMed

    Zhao, Haixiang; Jia, Yanxia; Ding, Mingyu; Sun, Dajiang; Zhao, Mengbin

    2011-05-01

    A multi-residue analytical method based on solid-phase extraction (SPE) with multiwalled carbon nanotubes (MWCNTs) as adsorbent was developed. The determination of 6 organochlorine pesticides and 7 pyrethroid pesticides in vegetables (including cucumber, cherry tomato, cabbage, lettuce, purple cabbage, leek, shallot and onion) was carried out by gas chromatography-electron capture detection (GC-ECD). The GC-ECD method used two columns (HP-50 and HP-1) and two ECD detectors. The HP-50 column was used for the analysis and the HP-1 column for validation. The clean-up conditions were optimized. The analytes were extracted by acetonitrile, and the extract was cleaned up by the MWCNTs SPE cartridge. The extract was re-dissolved by hexane, eluted with acetone-hexane (7:3, v/v) from the columns. The recoveries were over 70% for the 11 pesticides in the 13 pesticides. The results indicated that the MWCNTs SPE cartridge was efficient for 8 vegetable samples, because it reduced the contamination of the coloring materials to GC-ECD. The experimental results showed the MWCNTs SPE cartridge can adsorb the coloring materials and the eluant was nearly colorless. PMID:21847981

  5. Analysis of organophosphate flame retardants and plasticisers in water by isotope dilution gas chromatography-electron ionisation tandem mass spectrometry.

    PubMed

    Teo, Tiffany L L; McDonald, James A; Coleman, Heather M; Khan, Stuart J

    2015-10-01

    The widespread use of organophosphate flame retardants (PFRs) in commercial products have led to their increased presence in the environment. In this study, a rapid and reliable analytical method was developed for the analysis of five PFRs in water using gas chromatography tandem mass spectrometry (GC-MS/MS) with electron ionisation (EI) and a run time of 13 min. The PFRs investigated were tributyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCP) and triphenyl phosphate (TPP). Solid phase extraction (SPE) was undertaken to extract and concentrate target analytes from aqueous matrices. All water samples were extracted from a volume of 500 mL. Isotopically labelled compounds were used to account for analytical variability and for accurate quantification by isotope dilution. Method recoveries for all compounds were above 80% in all tested water samples. Method detection limits for all target analytes ranged from 0.3 to 24 ng/L in ultrapure water, tap water, seawater, surface water, secondary effluent and swimming pool water. Validation of this method confirmed satisfactory method stability with less than 1% coefficients of variation, verifying that this approach produced good reproducibility. PMID:26078137

  6. Optimization of matrix solid phase dispersion coupled with gas chromatography electron capture detection for determination of chlorinated pesticides in soil.

    PubMed

    Salemi, Amir; Shafiei, Elham; Vosough, Maryam

    2012-11-15

    A fast, simple and efficient technique based on matrix solid phase dispersion has been presented for extraction and clean-up of some chlorinated pesticides and derivative products; α-BHC, β-BHC, γ-BHC, δ-BHC, heptachlor, aldrin, dieldrin, endrin, endosulfan 1, endosulfan 2, 4,4'-DDT, 4,4'-DDE, 4,4'-DDD, heptachlor epoxide, endrin aldehyde, endosulfan sulfate. Box-Behnken response surface methodology was employed for optimization of the extraction efficiency. As the optimized procedure, 0.5 g of dried and sieved soil samples were mixed with 2.0 g of 10% C18 in silica (w/w) as dispersant and after transferring into the extraction tube they were extracted with 8 mL of dichloromethane-n-hexane (1:1, v/v). Gas chromatography with electron capture detector was used for selective and sensitive determination of the analytes. Recoveries for the extraction of the proposed analytes were calculated and were satisfying (more than 75%), except for endrin aldehyde (59%) and endosulfan sulfate (62%). Also the method was linear over the calibration range (R(2)>0.991) and the quantitative results were reasonably reproducible and sensitive (LODs ranged between 0.3 and 1.8 ng g(-1)).

  7. Ionization coefficients in gas mixtures

    NASA Astrophysics Data System (ADS)

    Marić, D.; Šašić, O.; Jovanović, J.; Radmilović-Rađenović, M.; Petrović, Z. Lj.

    2007-03-01

    We have tested the application of the common E/N ( E—electric field, N—gas number density) or Wieland approximation [Van Brunt, R.J., 1987. Common parametrizations of electron transport, collision cross section, and dielectric strength data for binary gas mixtures. J. Appl. Phys. 61 (5), 1773-1787.] and the common mean energy (CME) combination of the data for pure gases to obtain ionization coefficients for mixtures. Test calculations were made for Ar-CH4, Ar-N2, He-Xe and CH4-N2 mixtures. Standard combination procedure gives poor results in general, due to the fact that the electron energy distribution is considerably different in mixtures and in individual gases at the same values of E/N. The CME method may be used for mixtures of gases with ionization coefficients that do not differ by more than two orders of magnitude which is better than any other technique that was proposed [Marić, D., Radmilović-Rađenović, M., Petrović, Z.Lj., 2005. On parametrization and mixture laws for electron ionization coefficients. Eur. Phys. J. D 35, 313-321.].

  8. [Determination of eight polybrominated diphenyl ethers in marine sediments by ultrasonically assisted alkaline degradation extraction and gas chromatography-electron capture detection].

    PubMed

    Guoguang, Wang; Dahai, Zhang; Dandan, Yang; Jialin, Peng; Xianguo, Li

    2015-08-01

    For determination of the eight polybrominated diphenyl ethers (PBDEs) in marine sediments based on gas chromatography-electron capture detection (GC-ECD), a rapid and effective method for simultaneous sample extraction and purification was developed, in which ultrasonically assisted alkaline hydrolysis was combined with solvent extraction. The sediment sample was processed in an ultrasonic bath in 2. 00 mol/L NaOH-methanol solution for 30 min, and subsequently extracted by n-hexane. The organic phase was then separated and purified by silica column and concentrated to 100 µL for GC-ECD analysis. Under the optimized conditions, the recoveries and relative standard deviations (RSDs) for eight PBDE congeners ranged from 63.6% to 110.3% and from 1.7% to 10.5% (n = 5), respectively. The limits of detection (LODs, S/N = 3) ranged from 0.002 to 0.011 ng/g except for deca-brominated diphenyl ether (BDE-209), which was 0.097 ng/g. With high accuracy, good stability and adequate recovery, the established method was successfully applied to the analysis of PBDEs in the surface sediments from Bohai Sea. The concentrations of ∑8PBDEs (sum of 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2, 2', 4, 4', 5-pentabromodiphenyl ether (BDE-99), 2, 2', 4, 4', 6-pentabromodiphenyl ether (BDE100), 2, 2', 4, 4', 5, 5'- 1.566 to 6.760 ng/g and from 1.461 to 6.438 ng/g, respectively. A decreasing gradient of concentration was basically observed with increasing distance off the shore, indicating that anthropogenic activities, surface runoff and river inputs may be the sources of PBDEs in the sediments from Bohai Sea. PMID:26749867

  9. Relativistic ionization fronts in gas jets

    NASA Astrophysics Data System (ADS)

    Lemos, Nuno; Dias, J. M.; Gallacher, J. G.; Issac, R. C.; Fonseca, R. A.; Lopes, N. C.; Silva, L. O.; Mendonça, J. T.; Jaroszynski, D. A.

    2006-10-01

    A high-power ultra-short laser pulse propagating through a gas jet, ionizes the gas by tunnelling ionization, creating a relativistic plasma-gas interface. The relativistic ionization front that is created can be used to frequency up-shift electromagnetic radiation either in co-propagation or in counter-propagation configurations. In the counter-propagation configuration, ionization fronts can act as relativistic mirrors for terahertz radiation, leading to relativistic double Doppler frequency up-shift to the visible range. In this work, we identified and explored, the parameters that optimize the key features of relativistic ionization fronts for terahertz radiation reflection. The relativistic ionization front generated by a high power laser (TOPS) propagating in a supersonic gas jet generated by a Laval nozzle has been fully characterized. We have also performed detailed two-dimensional relativistic particle-in-cell simulations with Osiris 2.0 to analyze the generation and propagation of the ionization fronts.

  10. Liquid chromatography-electron ionization tandem mass spectrometry with the Direct-EI interface in the fast determination of diazepam and flunitrazepam in alcoholic beverages.

    PubMed

    Famiglini, Giorgio; Termopoli, Veronica; Palma, Pierangela; Cappiello, Achille

    2016-04-01

    This is the first application based on electron ionization (EI) using a Direct-EI LC interface and MS/MS to detect unequivocally target compounds in a very small real sample. The determination and quantification of benzodiazepines in very small residues of beverages, collected at the scene of drug-facilitated crimes are mandatory in legal procedures. A specific and sensitive analytical instrumentation is needed, involving little or no sample preparation. Here, a direct flow injection analysis of alcoholic beverages spiked with commercially available drugs containing diazepam and flunitrazepam is presented. The method proposed is very fast and requires neither sample preparation nor chromatographic separation. Linearity (R(2) ) was between 0.9977 and 0.9992; LOD and LOQ spanned from 0.01 to 0.02 ng/μL and from 0.1 to 0.5 ng/μL, respectively; intra- and interday repeatabilities were between 1 and 8%. No matrix effects were observed from the comparison of the linear regression curves obtained in real fortified samples and in pure ethanol. Vodka, whisky, and white wine specimens were fortified with commercial drugs, Valium(®) and Rohypnol(®) , at two different concentrations (20 and 50 ng/μL) to simulate the typical amounts found in adulterated real samples and analyzed to demonstrate the method applicability to forensic analyses.

  11. Gas chromatography-electron capture detection determination of Dacthal and its di-acid metabolite in soil after ultrasound-assisted extraction and in situ focused microwave-assisted derivatization.

    PubMed

    Caballo-López, A; Luque de Castro, M D

    2006-09-01

    A quantitative method for the determination of Dacthal and its di-acid metabolite in soil has been developed by coupling ultrasound-assisted extraction and microwave-assisted derivatization of the analytes prior to gas chromatography-electron capture detection for individual separation and measurement. The main factors affecting both extraction efficiency and derivatization were optimized by experimental design methodology. The proposed approach allows extraction of these pollutants from spiked sediment and soil with efficiencies similar to those provided by the reference method but with a drastic reduction of both the extraction and derivatization times. The repeatability of the analyses, expressed as RSD, of Dacthal and its di-acid metabolite was 4.6% and 5.4%, respectively; meanwhile, the RSD for within-laboratory reproducibility was 8.7% and 9.2%, respectively.

  12. Laboratory simulation of cometary neutral gas ionization

    NASA Astrophysics Data System (ADS)

    Chang, T.-F.; Rahman, H. U.; White, R. S.

    1989-05-01

    The laboratory simulation of the interaction of the solar wind with a comet is used to study the cometary neural gas ionization. The experiment is carried out in the UCR T-1 facility with an ice ball as the comet model. Photographs and data are taken with a variety of values of the solar wind velocity, interplanetary magnetic field (IMF), and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above certain minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. The critical magnetic field may be explained by assuming two stream lower hybrid instability as a triggering mechanism for the ionization of the neutral gas by plasma flow. Critical upper and lower limits for the magnetic field, required by anomalous ionization, are also derived that satisfy the experimental observations.

  13. Miniaturized gas ionization sensors using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Modi, Ashish; Koratkar, Nikhil; Lass, Eric; Wei, Bingqing; Ajayan, Pulickel M.

    2003-07-01

    Gas sensors operate by a variety of fundamentally different mechanisms. Ionization sensors work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge, bulky architecture, high power consumption and risky high-voltage operation. Here we report the fabrication and successful testing of ionization microsensors featuring the electrical breakdown of a range of gases and gas mixtures at carbon nanotube tips. The sharp tips of nanotubes generate very high electric fields at relatively low voltages, lowering breakdown voltages several-fold in comparison to traditional electrodes, and thereby enabling compact, battery-powered and safe operation of such sensors. The sensors show good sensitivity and selectivity, and are unaffected by extraneous factors such as temperature, humidity, and gas flow. As such, the devices offer several practical advantages over previously reported nanotube sensor systems. The simple, low-cost, sensors described here could be deployed for a variety of applications, such as environmental monitoring, sensing in chemical processing plants, and gas detection for counter-terrorism.

  14. Validation of high-throughput measurement system with microwave-assisted extraction, fully automated sample preparation device, and gas chromatography-electron capture detector for determination of polychlorinated biphenyls in whale blubber.

    PubMed

    Fujita, Hiroyuki; Honda, Katsuhisa; Hamada, Noriaki; Yasunaga, Genta; Fujise, Yoshihiro

    2009-02-01

    Validation of a high-throughput measurement system with microwave-assisted extraction (MAE), fully automated sample preparation device (SPD), and gas chromatography-electron capture detector (GC-ECD) for the determination of polychlorinated biphenyls (PCBs) in minke whale blubber was performed. PCB congeners accounting for > 95% of the total PCBs burden in blubber were efficiently extracted with a small volume (20 mL) of n-hexane using MAE due to simultaneous saponification and extraction. Further, the crude extract obtained by MAE was rapidly purified and automatically substituted to a small volume (1 mL) of toluene using SPD without using concentrators. Furthermore, the concentration of PCBs in the purified and concentrated solution was accurately determined by GC-ECD. Moreover, the result of accuracy test using a certified material (SRM 1588b; Cod liver oil) showed good agreement with the NIST certified concentration values. In addition, the method quantification limit of total-PCB in whale blubbers was 41 ng g(-1). This new measurement system for PCBs takes only four hours. Consequently, it indicated this method is the most suitable for the monitoring and screening of PCBs in the conservation of the marine ecosystem and safe distribution of foods.

  15. Use of green coating (cork) in solid-phase microextraction for the determination of organochlorine pesticides in water by gas chromatography-electron capture detection.

    PubMed

    Dias, Adriana Neves; Simão, Vanessa; Merib, Josias; Carasek, Eduardo

    2015-03-01

    A novel method for the determination of organochlorine pesticides in water samples with extraction using cork fiber and analysis by gas chromatography with electron capture detector was developed. Also, the procedure to extract these pesticides with DVB/Car/PDMS fiber was optimized. The optimization of the variables involved in the extraction of organochlorine pesticides using the aforementioned fibers was carried out by multivariate design. The optimum extraction conditions were sample temperature 75 °C, extraction time 60 min and sodium chloride concentration 10% for the cork fiber and sample temperature 50 °C and extraction time 60 min (without salt) for the DVB/Car/PDMS fiber. The quantification limits for the two fibers varied between 1.0 and 10.0 ng L(-1). The linear correlation coefficients were >0.98 for both fibers. The method applied with the use of the cork fiber provided recovery values between 60.3 and 112.7 and RSD≤25.5 (n=3). The extraction efficiency values for the cork and DVB/Car/PDMS fibers were similar. The results show that cork is a promising alternative as a coating for SPME.

  16. Gas chromatography/electron-capture negative ion mass spectrometry for the quantitative determination of 2- and 3-hydroxy fatty acids in bovine milk fat.

    PubMed

    Jenske, Ramona; Vetter, Walter

    2008-07-23

    2- and 3-hydroxy fatty acids (2- and 3-OH-FAs) are bioactive substances reported in sphingolipids and bacteria. Little is known of their occurrence in food. For this reason, a method suitable for the determination of OH-FAs at trace levels in bovine milk fat was developed. OH-FAs (and conventional fatty acids in samples) were converted into methyl esters and the hydroxyl group was derivatized with pentafluorobenzoyl (PFBO) chloride to give PFBO- O-FA methyl esters. These derivatives with strong electron affinity were determined by gas chromatography interfaced to mass spectrometry using electron-capture negative ion in the selected ion monitoring mode (GC/ECNI-MS-SIM). This method proved to be highly sensitive and selective for PFBO-O-FA methyl esters. For the analysis of samples, two internal standards were used. For this purpose, 9,10-dideutero-2-OH-18:0 methyl ester (ISTD-1) from 2-OH-18:1(9 c) methyl ester as well as the ethyl ester of 3-PFBO-O-12:0 (ISTD-2) was synthesized. ISTD-1 served as a recovery standard whereas ISTD-2 was used for GC/MS measurements. The whole-sample cleanup consisted of accelerated solvent extraction of dry bovine milk, addition of ISTD 1, saponification, conversion of fatty acids into methyl esters by use of boron trifluoride, separation of the methyl esters of OH-FAs from nonsubstituted FAs on activated silica, conversion of OH-FAs methyl esters into PFBO-O-FA methyl esters, addition of ISTD-2, and measurement by GC/ECNI-MS-SIM. By this method, ten OH-FAs were quantified in bovine milk fat with high precision in the range from 0.02 +/- 0.00 to 4.49 +/- 0.29 mg/100 g of milk fat.

  17. Hollow fiber liquid-liquid-liquid microextraction followed by solid-phase microextraction and in situ derivatization for the determination of chlorophenols by gas chromatography-electron capture detection.

    PubMed

    Saraji, Mohammad; Ghani, Milad

    2015-10-30

    A method based on the combination of hollow fiber liquid-liquid-liquid microextraction and solid-phase microextraction (SPME) followed by gas chromatography-electron capture detection was developed for the determination of chlorophenols in water and wastewater samples. Silica microstructures fabricated on the surface of a stainless steel wire were coated by an organic solvent and used as a SPME fiber. The analytes were extracted through a hollow fiber membrane containing n-decane from sample solution to an alkaline aqueous acceptor phase. They were then extracted and in situ derivatized on the SPME fiber using acetic anhydride. Experimental parameters such as the type of extraction solvent, acceptor phase NaOH concentration, donor phase HCl concentration, the amount of derivatizing reagent, salt concentration, stirring rate and extraction time were investigated and optimized. The precision of the method for the analytes at 0.02-30μgL(-1) concentration level ranged from 7.1 to 10.2% (as intra-day relative standard deviation) and 6.4 to 9.8% (as inter-day relative standard deviation). The linear dynamic ranges were in the interval of 5-500μgL(-1), 0.05-5μgL(-1), 0.02-1μgL(-1) and 0.001-0.5μgL(-1) for 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, respectively. The enrichment factors were between 432 and 785. The limits of detection were in the range of 0.0004-1.2μgL(-1). Tap water, well water and wastewater samples were also analyzed to evaluate the method capability for real sample analysis.

  18. Low density solvent based dispersive liquid-liquid microextraction with gas chromatography-electron capture detection for the determination of cypermethrin in tissues and blood of cypermethrin treated rats.

    PubMed

    Mudiam, Mohana Krishna Reddy; Jain, Rajeev; Maurya, Shailendra Kumar; Khan, Haider A; Bandyopadhyay, Sanghamitra; Murthy, R C

    2012-05-01

    A simple and rapid method to determine the cypermethrin (CYP) insecticide in rat tissues (kidney, liver and brain) and blood has been developed for the first time using low density solvent-dispersive liquid-liquid microextraction (LDS-DLLME) followed by gas chromatography-electron capture detector (GC-ECD) analysis. Initially, tissue samples containing CYP were homoginized in acetone. Subsequently, homogenate was mixed with n-hexane (extraction solvent) and the mixture was rapidly injected into water. The upper n-hexane layer was collected in a separate microtube and injected into GC-ECD for analysis. Blood samples were diluted with ultrapure water and subjected to DLLME through similar procedure. Parameters such as type and volume of disperser and extraction solvent, salting out effect and extraction time, which can affect the extraction efficiency of DLLME, were optimized. Method was validated by investigating linearity, precision, recovery, limit of detection (LOD) and quantification (LOQ). LODs in tissue were in the range of 0.043-0.314 ng mg(-1) and for blood it was 8.6 ng mL(-1) with a signal to noise ratio of 3:1. LOQs in tissue were in the range of 0.143-1.03 ng mg(-1) and for blood it was 28.3 ng mL(-1) with a signal to noise ratio of 10:1. Mean recoveries of CYP at three different concentation levels in all the matrices were found to be in the range of 81.6-103.67%. The results show that, LDS-DLLME coupled with GC-ECD offers a simple, rapid and efficient technique for extraction and determination of CYP in rat tissues and blood samples, which in turn would be useful for toxicological studies of CYP.

  19. Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2008-07-15

    Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

  20. WHAM observations of ionized gas in the inner Milky Way

    NASA Astrophysics Data System (ADS)

    Hill, Alex S.; Haffner, L. Matthew; Benjamin, Robert A.; Gostisha, Martin; Barger, Kathleen

    2016-01-01

    We present Wisconsin H-Alpha Mapper (WHAM) observations of ionized gas in the southern Milky Way. We include spectroscopic maps of H-Alpha, [S II], and [N II]. The data includes the Scutum-Centaurus Arm, for which we measure an exponential scale height about 20% less than that in the Perseus Arm in the outer Galaxy. The H-alpha scale height suggests a lower electron scale height in both arms than is measured locally from pulsar dispersion. The [N II] and [S II] data provide information about the temperature and ionization state of the gas: gas in the warm ionized medium is generally warmer (≈8000 K) and in lower ionization states than gas in classical H II regions. WHAM research and operations are supported through NSF Award AST-1108911.

  1. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    SciTech Connect

    Shneider, Mikhail N.; Miles, Richard B.

    2012-08-15

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  2. Simultaneous screening for and determination of 128 date-rape drugs in urine by gas chromatography-electron ionization-mass spectrometry.

    PubMed

    Adamowicz, Piotr; Kała, Maria

    2010-05-20

    Date-rape drugs (DRDs) are used for the purpose of "drugging" unsuspected victims and raping or robbing them while under the influence of the drug. The wide variety of substances used for criminal purposes, their low concentrations in body fluids and, often, a long time delay between the event and clinical examination make comprehensive screening analysis of biological materials collected from crime victims for the presence of these drugs very difficult. Detection of a drug used to facilitate sexual assault in biological fluids can be very important evidence of a committed crime. The purpose of this study was to develop a simple GC-EI-MS screening procedure for date-rape drugs in urine. Target analytes were isolated by solid-phase extraction. 2-mL urine samples were extracted and then derivatized by using BSTFA+1%TMCS reagent. Detection of all compounds was based on full-scan mass spectra and for each compound one ion was chosen for further quantification. The method allowed the simultaneous screening, detection and quantification of 128 compounds from different groups (number of compounds): opioids (20), amphetamines (11), GHB and related products (3), hallucinogens (9), benzodiazepines (18), antihistamines (9), antidepressants (14), selective serotonin-reuptake inhibitors (4), antipsychotics (7), barbiturates (7), other sedatives (5), muscle relaxants (2) and other drugs (19). The procedure can easily be expanded to encompass more substances. The developed method appeared to be suitable for screening for the target DRDs. The procedure was successfully applied to the analysis of authentic urine samples collected from victims of rapes and other crimes in routine casework. PMID:20207513

  3. Simultaneous screening for and determination of 128 date-rape drugs in urine by gas chromatography-electron ionization-mass spectrometry.

    PubMed

    Adamowicz, Piotr; Kała, Maria

    2010-05-20

    Date-rape drugs (DRDs) are used for the purpose of "drugging" unsuspected victims and raping or robbing them while under the influence of the drug. The wide variety of substances used for criminal purposes, their low concentrations in body fluids and, often, a long time delay between the event and clinical examination make comprehensive screening analysis of biological materials collected from crime victims for the presence of these drugs very difficult. Detection of a drug used to facilitate sexual assault in biological fluids can be very important evidence of a committed crime. The purpose of this study was to develop a simple GC-EI-MS screening procedure for date-rape drugs in urine. Target analytes were isolated by solid-phase extraction. 2-mL urine samples were extracted and then derivatized by using BSTFA+1%TMCS reagent. Detection of all compounds was based on full-scan mass spectra and for each compound one ion was chosen for further quantification. The method allowed the simultaneous screening, detection and quantification of 128 compounds from different groups (number of compounds): opioids (20), amphetamines (11), GHB and related products (3), hallucinogens (9), benzodiazepines (18), antihistamines (9), antidepressants (14), selective serotonin-reuptake inhibitors (4), antipsychotics (7), barbiturates (7), other sedatives (5), muscle relaxants (2) and other drugs (19). The procedure can easily be expanded to encompass more substances. The developed method appeared to be suitable for screening for the target DRDs. The procedure was successfully applied to the analysis of authentic urine samples collected from victims of rapes and other crimes in routine casework.

  4. The distribution of warm ionized gas in NGC 891

    NASA Technical Reports Server (NTRS)

    Rand, Richard J.; Kulkarni, Shrinivas R.; Hester, J. Jeff

    1990-01-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals.

  5. The Kinematics of the Ionized Gas in IC 10

    NASA Astrophysics Data System (ADS)

    Thurow, Joshua C.; Wilcots, Eric M.

    2005-02-01

    We present the results of a WIYN integral field unit study of the kinematics of the ionized gas in IC 10, a dwarf irregular starburst galaxy in the Local Group. Though the velocity field of the ionized gas closely matches that of the H I, there are several kinematically interesting features in the galaxy. The diffuse ionized gas in the galaxy exhibits larger Hα line widths than the bright complexes. In one case this is due to an infusion of energy into the gas associated with the radio superbubble discovered by Yang & Skillman. We find that the amount of energy in this region is consistent with their hypothesis that the region contains 10 supernova remnants. We also detect a high-velocity (70 km s-1) expanding shell in the ionized gas, which is likely driven by three confirmed Wolf-Rayet stars that are located within the shell. Extrapolating from Hunter's initial mass function, we find that the central starburst region contains approximately equal energy contributions from stellar winds and supernovae (SNe), suggesting that SNe are just beginning to play a significant role in shaping the kinematics of the ionized gas. However, all of this energy cannot be easily accounted for in the kinematics of the gas. We detect an energetic flow of gas (3×1052 ergs), which we believe originates from the starburst region. We also detect a high-velocity (70 km s-1) feature not coincident with any structure in our Hα image. This feature, along with the flow and shell, can account for the energy produced by stellar wind and SNe. The flow resembles one discovered by Wilcots & Thurow in NGC 4214; together they suggest that the porosity of the interstellar medium contributes significantly to the high velocity of some portion of the ionized gas in irregular galaxies.

  6. Surface Ionization Gas Detection at SnO2 Surfaces

    NASA Astrophysics Data System (ADS)

    Krenkow, A.; Oberhüttinger, C.; Habauzit, A.; Kessler, M.; Göbel, J.; Müller, G.

    2009-05-01

    In surface ionization (SI) gas detection adsorbed analyte molecules are converted into ionic species at a heated solid surface and extracted into free space by an oppositely biased counter electrode. In the present work we consider the formation of positive and negative analyte gas ions at SnO2 surfaces. We find that SI leads to positive ion formation only, with the SI efficiency scaling with the ionization energy of the analyte gas molecules. Aromatic and aliphatic hydrocarbons with amine functional groups exhibit particularly high SI efficiencies.

  7. Ionization of vitamin C in gas phase: Theoretical study.

    PubMed

    Abyar, Fatemeh; Farrokhpour, Hossein

    2016-07-01

    In this work, the gas phase ionization energies and photoelectron spectra of four important conformers of vitamin C were calculated. Symmetry adapted cluster/configuration interaction methodology employing the single and double excitation operators (SAC-CI SD-R) along with D95++(d,p) basis set were used for the calculations. Thermochemistry calculations were also performed on all possible conformers of vitamin C to find the relative stability of conformers in the gas phase. The calculated ionization bands of each conformer were assigned by calculating the contribution of natural bonding orbital (NBO) in the calculated canonical molecular orbitals involved in the ionization. SAC-CI calculations showed that the first ionization band of vitamin C is related to the π electrons of CC bond of the ring of molecule although, there is the lone electron pairs of oxygen atoms and π electrons of CO bond in the molecule. PMID:27092998

  8. Superequilibrium ionization during adiabatic expansion of a relaxing gas

    NASA Astrophysics Data System (ADS)

    Achasov, O. V.; Zhdanok, S. A.; Soloukhin, R. I.; Fomin, N. A.

    1980-08-01

    A superequilibrium method for the generation of a weakly ionized plasma in a molecular gas is proposed; the method involves the production of a superequilibrium electron density in a thermally excited and vibrationally frozen molecular gas during expansion in supersonic flow. Experimental results are presented for the case of nitrogen. This method has applications in molecular and laser physics, including preionization in a fast-flow gas-discharge laser, and the study of energy losses in gasdynamic lasers.

  9. IONIZED GAS IN THE GALACTIC CENTER: NEW OBSERVATIONS AND INTERPRETATION

    SciTech Connect

    Irons, Wesley T.; Lacy, John H.; Richter, Matthew J.

    2012-08-20

    We present new observations of the [Ne II] emission from the ionized gas in Sgr A West with improved resolution and sensitivity. About half of the emission comes from gas with kinematics indicating it is orbiting in a plane tipped about 25 Degree-Sign from the Galactic plane. This plane is consistent with that derived previously for the circumnuclear molecular disk and the northern arm and western arc ionized features. However, unlike most previous studies, we conclude that the ionized gas is not moving along the ionized features, but on more nearly circular paths. The observed speeds are close to, but probably somewhat less than expected for orbital motions in the potential of the central black hole and stars and have a small inward component. The spatial distribution of the emission is well fitted by a spiral pattern. We discuss possible physical explanations for the spatial distribution and kinematics of the ionized gas, and conclude that both may be best explained by a one-armed spiral density wave, which also accounts for both the observed low velocities and the inward velocity component. We suggest that a density wave may result from the precession of elliptical orbits in the potential of the black hole and stellar mass distribution.

  10. Atmospheric pressure chemical ionization source. 1. Ionization of compounds in the gas phase.

    PubMed

    Andrade, Francisco J; Shelley, Jacob T; Wetzel, William C; Webb, Michael R; Gamez, Gerardo; Ray, Steven J; Hieftje, Gary M

    2008-04-15

    A novel chemical ionization source for organic mass spectrometry is introduced. This new source uses a glow discharge in the flowing afterglow mode for the generation of excited species and ions. The direct-current gas discharge is operated in helium at atmospheric pressure; typical operating voltages and currents are around 500 V and 25 mA, respectively. The species generated by this atmospheric pressure glow discharge are mixed with ambient air to generate reagent ions (mostly ionized water clusters and NO+), which are then used for the ionization of gaseous organic compounds. A wide variety of substances, both polar and nonpolar, can be ionized. The resulting mass spectra generally show the parent molecular ion (M+ or MH+) with little or no fragmentation. Proton transfer from ionized water clusters has been identified as the main ionization pathway. However, the presence of radical molecular ions (M+) for some compounds indicates that other ionization mechanisms are also involved. The analytical capabilities of this source were evaluated with a time-of-flight mass spectrometer, and preliminary characterization shows very good stability, linearity, and sensitivity. Limits of detection in the single to tens of femtomole range are reported for selected compounds. PMID:18345693

  11. Plasma induced by resonance enhanced multiphoton ionization in inert gas

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2007-12-15

    We present a detailed model for the evolution of resonance enhanced multiphoton ionization (REMPI) produced plasma during and after the ionizing laser pulse in inert gas (argon, as an example) at arbitrary pressures. Our theory includes the complete process of the REMPI plasma generation and losses, together with the changing gas thermodynamic parameters. The model shows that the plasma expansion follows a classical ambipolar diffusion and that gas heating results in a weak shock or acoustic wave. The gas becomes involved in the motion not only from the pressure gradient due to the heating, but also from the momentum transfer from the charged particles to gas atoms. The time dependence of the total number of electrons computed in theory matches closely with the results of coherent microwave scattering experiments.

  12. Similarity of ionized gas nebulae around unobscured and obscured quasars

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.

    2014-08-01

    Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper, we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O III] λ5007 Å emission line. We find that ionized gas nebulae extend out to ˜13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O III] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore, in samples of obscured and unobscured quasars carefully matched in [O III] luminosity, we find support for the standard geometry-based unification model of active galactic nuclei, in that the intrinsic properties of the quasars, of their hosts and of their ionized gas appear to be very similar. Given the apparent ubiquity of extended ionized regions, we are forced to conclude that either the quasar is at least partially illuminating pre-existing gas or that both samples of quasars are seen during advanced stages of quasar feedback. In the latter case, we may be biased by our [O III]-based selection against quasars in the early `blow-out' phase, for example due to dust obscuration.

  13. Fabrication of a miniaturized ionization gas sensor with polyimide spacer

    NASA Astrophysics Data System (ADS)

    Walewyns, T.; Scheen, G.; Tooten, E.; El Fissi, L.; Dupuis, P.; Francis, L. A.

    2011-06-01

    Gas sensing can be achieved by fingerprinting the ionization characteristics of distinct species. In this study, the fabrication of a miniaturized gas ionization sensor using polyimide as sacrificial layer is reported. The sensor consists of two planar metallic electrodes with a gap spacing obtained by the polyimide under-etching. This known sacrificial layer has the advantage besides a high planarization factor, to be CMOS compatible. Furthermore, its chemical resistance up to high temperatures, high resistance to radiation from both electrons and neutrons, and low outgassing are of primary importance to avoid interferences with the ionization gas sensing. A suspended micro-bridge with dimensions 20 μm width and 220 μm length has been developed and released by using etching holes in the membrane. The ionization characteristics of air at controlled temperature, humidity and pressure (21°C, 40% humidity and 1 atm) have been obtained during non-destructive electrical characterizations, with a breakdown voltage of 350 V for a 6 μm gap. The growth of metallic nanowires templated in ion track-etched polyimide on the electrode is envisioned in order to enhance the ionization field and to reduce the required measurement power of the sensor.

  14. The distribution of warm ionized gas in NGC 891

    SciTech Connect

    Rand, R.J.; Kulkarni, S.R.; Hester, J.J. Infrared Processing and Analysis Center, Pasadena, CA )

    1990-03-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals. 19 refs.

  15. Viscosity Coefficient Curve Fits for Ionized Gas Species Grant Palmer

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Arnold, James O. (Technical Monitor)

    2001-01-01

    Viscosity coefficient curve fits for neutral gas species are available from many sources. Many do a good job of reproducing experimental and computational chemistry data. The curve fits are usually expressed as a function of temperature only. This is consistent with the governing equations used to derive an expression for the neutral species viscosity coefficient. Ionized species pose a more complicated problem. They are subject to electrostatic as well as intermolecular forces. The electrostatic forces are affected by a shielding phenomenon where electrons shield the electrostatic forces of positively charged ions beyond a certain distance. The viscosity coefficient for an ionized gas species is a function of both temperature and local electron number density. Currently available curve fits for ionized gas species, such as those presented by Gupta/Yos, are a function of temperature only. What they did was to assume an electron number density. The problem is that the electron number density they assumed was unrealistically high. The purpose of this paper is two-fold. First, the proper expression for determining the viscosity coefficient of an ionized species as a function of both temperature and electron number density will be presented. Then curve fit coefficients will be developed using the more realistic assumption of an equilibrium electron number density. The results will be compared against previous curve fits and against highly accurate computational chemistry data.

  16. Kinematics of the Ionized Gas in Dwarf Irregular Galaxies

    NASA Astrophysics Data System (ADS)

    Valdez-Gutiérrez, Margarita; Rosado, Margarita

    2007-05-01

    Introduction: Some preliminary results focused on the kinematics and dynamics of the ionized gas in the local group dwarf irregular galaxy IC10 are presented. Method: Scanning Fabry-Perot interferometry was performed in the Hα, [SII], [NII] and [OIII] lines. The dedicated ADHOC package was used in the reduction process. Results: On galactic scales the radial velocity field in this galaxy is relatively well behaved, however, the rotation curve has been difficult to obtain. On local scales the kinematics reflects the superposition of shells, filaments, SNRs and diffuse gas. At many of these locations the velocity widths are supersonic and many times larger than those found in the adjacent HII regions. Discussion: This is the first time that the kinematics of the ionized gas in the dwarf irregular IC10 is studied in great detail, literally pixel to pixel with moderate spectral and spatial resolutions. From these preliminary results a very complex behavior of the ionized gas is unveiled, as has been the case for the dwarf irregulars IC1613 and NGC4449, previously studied by our group of collaborators. Further analysis is being carried out.

  17. Gas ionization sensors with carbon nanotube/nickel field emitters.

    PubMed

    Huang, Bohr-Ran; Lin, Tzu-Ching; Yang, Ying-Kan; Tzeng, Shien-Der

    2011-12-01

    Gas ionization sensors based on the field emission properties of the carbon nanotube/nickel (CNT/Ni) field emitters were first developed in this work. It is found that the breakdown electric field (E(b)) slightly decreases from 2.2 V/microm to 1.9 V/microm as the pressure of H2 gas increases from 0.5 Torr to 100 Torr. On the contrary, E(b) obviously increases from 2.9 V/microm to 6.5 V/microm as O2 gas pressure increases from 0.5 Torr to 100 Torr. This may be explained by the depression of the electron emission that caused by the adsorption of the O2 gas on the CNT emitters. The Raman spectra of the CNT/Ni emitters also show that more defects were generated on the CNTs after O2 gas sensing. The Joule heating effect under high current density as performing H2 sensing was also observed. These effects may contribute the pressure dependence on the breakdown electric field of the CNT/Ni gas ionization sensors. PMID:22409010

  18. Ionized gas at the edge of the central molecular zone

    NASA Astrophysics Data System (ADS)

    Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.; Velusamy, T.; Requena-Torres, M. A.; Wiesemeyer, H.

    2015-04-01

    Context. The edge of the central molecular zone (CMZ) is the location where massive dense molecular clouds with large internal velocity dispersions transition to the surrounding more quiescent and lower CO emissivity region of the Galaxy. Little is known about the ionized gas surrounding the molecular clouds and in the transition region. Aims: We determine the properties of the ionized gas at the edge of the CMZ near Sgr E using observations of N+ and C+. Methods: We observed a small portion of the edge of the CMZ near Sgr E with spectrally resolved [C ii] 158 μm and [N ii] 205 μm fine structure lines at six positions with the GREAT instrument on SOFIA and in [C ii] using Herschel HIFI on-the-fly strip maps. We use the [N ii] spectra along with a radiative transfer model to calculate the electron density of the gas and the [C ii] maps to illuminate the morphology of the ionized gas and model the column density of CO-dark H2. Results: We detect two [C ii] and [N ii] velocity components, one along the line of sight to a CO molecular cloud at - 207 km s-1 associated with Sgr E and the other at -174 km s-1 outside the edge of another CO cloud. From the [N ii] emission we find that the average electron density is in the range of ~5 to 21 cm-3 for these features. This electron density is much higher than that of the disk's warm ionized medium, but is consistent with densities determined for bright diffuse H ii nebula. The column density of the CO-dark H2 layer in the -207 km s-1 cloud is ~1-2 × 1021 cm-2 in agreement with theoretical models. The CMZ extends further out in Galactic radius by ~7 to 14 pc in ionized gas than it does in molecular gas traced by CO. Conclusions: The edge of the CMZ likely contains dense hot ionized gas surrounding the neutral molecular material. The high fractional abundance of N+ and high electron density require an intense EUV field with a photon flux of order 106 to 107 photons cm-2 s-1, and/or efficient proton charge exchange with

  19. Ionizing gas breakdown waves in strong electric fields.

    NASA Technical Reports Server (NTRS)

    Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

    1972-01-01

    A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

  20. Resonance ionization spectroscopy: counting noble-gas atoms

    SciTech Connect

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-06-01

    New work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions) is reported. When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. It is shown that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective.

  1. Turbulence in the Ionized Gas of the Orion Nebula

    NASA Astrophysics Data System (ADS)

    Arthur, S. J.; Medina, S.-N. X.; Henney, W. J.

    2016-08-01

    In order to study the nature, origin, and impact of turbulent velocity fluctuations in the ionized gas of the Orion Nebula, we apply a variety of statistical techniques to observed velocity cubes. The cubes are derived from high resolving power (R ≈ 40 000) longslit spectroscopy of optical emission lines that span a range of ionizations. From Velocity Channel Analysis (VCA), we find that the slope of the velocity power spectrum is consistent with predictions of Kolmogorov theory between scales of 8 and 22 arcsec (0.02 to 0.05 pc). The outer scale, which is the dominant scale of density fluctuations in the nebula, approximately coincides with the autocorrelation length of the velocity fluctuations that we determine from the second order velocity structure function. We propose that this is the principal driving scale of the turbulence, which originates in the autocorrelation length of dense cores in the Orion molecular filament. By combining analysis of the non-thermal line widths with the systematic trends of velocity centroid versus ionization, we find that the global champagne flow and smaller scale turbulence each contribute in equal measure to the total velocity dispersion, with respective root-mean-square widths of 4-5 km s-1. The turbulence is subsonic and can account for only one half of the derived variance in ionized density, with the remaining variance provided by density gradients in photoevaporation flows from globules and filaments. Intercomparison with results from simulations implies that the ionized gas is confined to a thick shell and does not fill the interior of the nebula.

  2. Two-step laser ionization schemes for in-gas laser ionization and spectroscopy of radioactive isotopes

    SciTech Connect

    Kudryavtsev, Yu. Ferrer, R.; Huyse, M.; Van den Bergh, P.; Van Duppen, P.; Vermeeren, L.

    2014-02-15

    The in-gas laser ionization and spectroscopy technique has been developed at the Leuven isotope separator on-line facility for the production and in-source laser spectroscopy studies of short-lived radioactive isotopes. In this article, results from a study to identify efficient optical schemes for the two-step resonance laser ionization of 18 elements are presented.

  3. Aerodynamic Effects in Weakly Ionized Gas: Phenomenology and Applications

    SciTech Connect

    Popovic, S.; Vuskovic, L.

    2006-12-01

    Aerodynamic effects in ionized gases, often neglected phenomena, have been subject of a renewed interest in recent years. After a brief historical account, we discuss a selected number of effects and unresolved problems that appear to be relevant in both aeronautic and propulsion applications in subsonic, supersonic, and hypersonic flow. Interaction between acoustic shock waves and weakly ionized gas is manifested either as plasma-induced shock wave dispersion and acceleration or as shock-wave induced double electric layer in the plasma, followed by the localized increase of the average electron energy and density, as well as enhancement of optical emission. We describe the phenomenology of these effects and discuss several experiments that still do not have an adequate interpretation. Critical for application of aerodynamic effects is the energy deposition into the flow. We classify and discuss some proposed wall-free generation schemes with respect to the efficiency of energy deposition and overall generation of the aerodynamic body force.

  4. Triggered star formation in giant HI supershells: ionized gas

    NASA Astrophysics Data System (ADS)

    Egorov, O. V.; Lozinskaya, T. A.; Moiseev, A. V.

    We considered the regions of triggered star formation inside kpc-sized HI supershells in three dwarf galaxies: IC 1613, IC 2574 and Holmberg II. The ionized and neutral gas morphology and kinematics were studied based on our observations with scanning Fabry-Perot interferometer at the SAO RAS 6-m telescope and 21 cm archival data of THINGS and LITTLE THINGS surveys. Qualitative analysis of the observational data was performed in order to highlight two questions: why the star formation occurred very locally in the supershells, and how the ongoing star formation in HI supershells rims influence its evolution? During the investigation we discovered the phenomenon never before observed in galaxies IC 2574 and Holmberg II: we found faint giant (kpc- sized) ionized shells in H-alpha and [SII]6717,6731 lines inside the supergiant HI shells.

  5. Residual-gas-ionization beam profile monitors in RHIC

    SciTech Connect

    Connolly, R.; Fite, J.; Jao, S.; Trabocchi, C.

    2010-05-02

    Four ionization profile monitors (IPMs) are in RHIC to measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. During the last two years both the collection accuracy and signal/noise ratio have been improved. An electron source is mounted across the beam pipe from the collector to monitor microchannel plate (MCP) aging and the signal electrons are gated to reduce MCP aging and to allow charge replenishment between single-turn measurements. Software changes permit simultaneous measurements of any number of individual bunches in the ring. This has been used to measure emittance growth rates on six bunches of varying intensities in a single store. Also the software supports FFT analysis of turn-by-turn profiles of a single bunch at injection to detect dipole and quadrupole oscillations.

  6. Equation of state for a partially ionized gas. II.

    PubMed

    Baker, George A

    2003-11-01

    The derivation of equations of state for fluid phases of a partially ionized gas or plasma is addressed from a fundamental point of view. A spherical cellular model is deduced for the hot curve limit (or ideal Fermi gas). Next the Coulomb interactions are added to the spherical cellular model for general ionic charge Z. Then an independent electron model within a Z electron cell plus several many-body effects are employed. Numerical examples of the theory for several elements (H, Li, N, Na, K, Ni, Rb, Pd, Cs, and Er) are reported. These results reduce in various limits of temperature and density to the expected behavior. They display electron, localization-delocalization phase transitions of liquid-gas character. In the higher Z elements, a second possible critical point has been found. The critical pressure, electron density and temperature for the lower-density critical points seem to obey power laws as a function of Z.

  7. Suitability of magnetic particle immunoassay for the analysis of PBDEs in Hawaiian freshwater fish and crabs in comparison with gas chromatography/electron capture detection-ion trap mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A gas chromatograph/electron capture detector-ion trap mass spectrometer (GC/ECD-ITMS) was used for the determination of polybrominated diphenyl ethers (PBDEs) in freshwater fish and crabs. The samples were also analyzed with an enzyme-linked immunosorbent assay (ELISA). GC/ECD-ITMS results showed...

  8. Evaluation of automated stir bar sorptive extraction-thermal desorption-gas chromatography electron capture negative ion mass spectrometry for the analysis of PBDEs and PBBs in sheep and human serum.

    PubMed

    Loconto, Paul R

    2009-09-01

    Stir-bar sorptive extraction and automated thermal desorption/cryotrapping interfaced to capillary gas chromatography and electron capture negative ion mass spectrometry is shown to effectively isolate and recover polybrominated diphenyl ethers and polybrominated biphenyls from sheep and human serum. This paper describes the development of the method and demonstrates the feasibility of using Twister with spiked serum. Conditions for conducting stir-bar sorptive extraction and for automated thermal desorption that led to acceptable analyte recoveries were optimized. The approach to sample preparation introduced here significantly reduces tedious labor and solvent consumption associated with conventional liquid-liquid extraction. PMID:19772742

  9. Ionized Gas Observation Toward a Nearby Starburst Galaxy NGC 253

    NASA Astrophysics Data System (ADS)

    Nakanishi, K.; Sorai, K.; Nakai, N.; Kuno, N.; Matsubayashi, K.; Sugai, H.; Takano, S.; Kohno, K.; Nakajima, T.

    2015-12-01

    ALMA observation of a hydrogen recombination emission line toward NGC 253 was performed. NGC 253 is a prototypical starburst galaxy in the nearby universe. The recombination line was clearly detected in the central region of NGC 253 with a spatial resolution of few dozens of parsecs at the galaxy. The line and thermal free-free continuum emission show quite similar spatial distribution, and this fact shows the recombination line certainly traces ionized gas formed by young massive stars. Estimated electron temperature (6500-9000K) from the data are similar to those of Galactic HII regions. The recombination line has large velocity width at the center of the galaxy, and the velocity structure is quite different from that of molecular emission line.

  10. Parallel plate ionization chamber in low pressure helium gas

    NASA Astrophysics Data System (ADS)

    Frank, D.; Heinz, A.; Winkler, R.; Qian, J.; Casperson, R. J.; Terry, J. R.

    2007-10-01

    A parallel plate ionization chamber was constructed for beam intensity monitoring. The chamber is placed in a gas-filled volume 1.5m upstream from the gas-filled separator SASSYER. Its output current will be used to determine absolute reaction cross sections. In a dedicated test experiment with a 100 MeV ^32S beam and an applied potential of 300V, the signal current had an average standard deviation of 0.4%, and demonstrated a linear relationship (R^2 = 0.9894) with the beam intensity. Also, at an intensity of 6 particle nanoamperes, the current exhibited a linear dependence (R^2 = 0.9813) on voltage, indicating that the chamber was operating in the proportional counter region. Our results agreed well with predictions made using extrapolated Townsend coefficients, though we observed a constant systematic and constant deviation between these estimates and our output current. This work was supported under US DOE grant number DE-FG0291ER-40609 and the Yale College Dean's Fellowship for Research in the Sciences.

  11. The Impact of Diffuse Ionized Gas on Emission-line Ratios and Gas Metallicity Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Yan, Renbin; MaNGA Team

    2016-01-01

    Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impact the measurements of emission line ratios, hence the gas-phase metallicity measurements and the interpretation of diagnostic diagrams. We demonstrate that emission line surface brightness (SB) is a reasonably good proxy to separate HII regions from regions dominated by diffuse ionized gas. For spatially-adjacent regions or regions at the same radius, many line ratios change systematically with emission line surface brightness, reflecting a gradual increase of dominance by DIG towards low SB. DIG could significantly bias the measurement of gas metallicity and metallicity gradient. Because DIG tend to have a higher temperature than HII regions, at fixed metallicity DIG displays lower [NII]/[OII] ratios. DIG also show lower [OIII]/[OII] ratios than HII regions, due to extended partially-ionized regions that enhance all low-ionization lines ([NII], [SII], [OII], [OI]). The contamination by DIG is responsible for a substantial portion of the scatter in metallicity measurements. At different surface brightness, line ratios and line ratio gradients can differ systematically. As DIG fraction could change with radius, it can affect the metallicity gradient measurements in systematic ways. The three commonly used strong-line metallicity indicators, R23, [NII]/[OII], O3N2, are all affected in different ways. To make robust metallicity gradient measurements, one has to properly isolate HII regions and correct for DIG contamination. In line ratio diagnostic diagrams, contamination by DIG moves HII regions towards composite or LINER-like regions.

  12. Plasma channel created by ionization of gas by a surface wave

    SciTech Connect

    Konovalov, V. N.; Kuz’min, G. P.; Minaev, I. M. Rukhadze, A. A.; Tikhonevich, O. V.

    2015-09-15

    Conditions for gas ionization in the field of a slow surface wave excited by a microwave source are considered. The gas ionization rate and the plasma density distribution over the radius of the discharge tube were studied by the optical method. The experiments were conducted in a dielectric tube with a radius much smaller than the tube length, the gas pressure being ∼1–3 Torr. It is shown that the stationary distribution of the plasma density is determined by diffusion processes.

  13. A new mini gas ionization chamber for IBA applications

    NASA Astrophysics Data System (ADS)

    Müller, A. M.; Cassimi, A.; Döbeli, M.; Mallepell, M.; Monnet, I.; Simon, M. J.; Suter, M.; Synal, H.-A.

    2011-12-01

    Novel prototypes of high resolution gas ionization chambers ( GIC) were designed with increased compactness and simplicity of the setup. They have no Frisch-grid and a simple anode wire. Under certain operating conditions these mini detectors have an energy resolution comparable with that of state-of-the-art GICs of much higher complexity. They can be operated both under vacuum and atmospheric pressure. First measurements were made with protons in the energy range of 0.3-1.0 MeV. For protons at 0.3 MeV an energy resolution of about 12 keV was achieved. With a 72 MeV 129Xe beam a relative resolution of 1.4% was obtained. Due to their versatility and reduced size the detectors can easily be applied in the field of ion beam analysis ( IBA) and accelerator mass spectrometry ( AMS) . Since they are almost completely insensitive to radiation damage they are especially suited for use in high fluence applications such as scanning transmission ion microscopy ( STIM). A comparison of the radiation hardness of the mini GIC with a Si PIN diode was therefore performed. The GIC showed no peak shift or change in energy resolution at all after collecting 10 15 protons per cm 2 while the performance of the Si detector clearly started to degrade at 10 12 particles per cm 2.

  14. Alfvén ionization in an MHD-gas interactions code

    NASA Astrophysics Data System (ADS)

    Wilson, A. D.; Diver, D. A.

    2016-07-01

    A numerical model of partially ionized plasmas is developed in order to capture their evolving ionization fractions as a result of Alfvén ionization (AI). The mechanism of, and the parameter regime necessary for, AI is discussed and an expression for the AI rate based on fluid parameters, from a gas-MHD model, is derived. This AI term is added to an existing MHD-gas interactions' code, and the result is a linear, 2D, two-fluid model that includes momentum transfer between charged and neutral species as well as an ionization rate that depends on the velocity fields of both fluids. The dynamics of waves propagating through such a partially ionized plasma are investigated, and it is found that AI has a significant influence on the fluid dynamics as well as both the local and global ionization fraction.

  15. Electron impact ionization of the gas-phase sorbitol

    NASA Astrophysics Data System (ADS)

    Chernyshova, Irina; Markush, Pavlo; Zavilopulo, Anatoly; Shpenik, Otto

    2015-03-01

    Ionization and dissociative ionization of the sorbitol molecule by electron impact have been studied using two different experimental methods. In the mass range of m/ z = 10-190, the mass spectra of sorbitol were recorded at the ionizing electron energies of 70 and 30 eV. The ion yield curves for the fragment ions have been analyzed and the appearance energies of these ions have been determined. The relative total ionization cross section of the sorbitol molecule was measured using monoenergetic electron beam. Possible fragmentation pathways for the sorbitol molecule were proposed.

  16. Nearby early-type galaxies with ionized gas. IV. Origin and powering mechanism of the ionized gas

    NASA Astrophysics Data System (ADS)

    Annibali, F.; Bressan, A.; Rampazzo, R.; Zeilinger, W. W.; Vega, O.; Panuzzo, P.

    2010-09-01

    Aims: A significant fraction of early-type galaxies (ETGs) exhibit emission lines in their optical spectra. We attempt to identify the producing the emission mechanism and the ionized gas in ETGs, and its connection with the host galaxy evolution. Methods: We analyzed intermediate-resolution optical spectra of 65 ETGs, mostly located in low density environments and exhibiting spectros-copic diagnostic lines of ISM from which we had previously derived stellar population properties. To extract the emission lines from the galaxy spectra, we developed a new fitting procedure that accurately subtracts the underlying stellar continuum, and accounts for the uncertainties caused by the age-metallicity degeneracy. Results: Optical emission lines are detected in 89% of the sample. The incidence and strength of emission correlate with neither the E/S0 classification, nor the fast/slow rotator classification. By means of the classical [OIII]/Hβ versus [NII]/Hα diagnostic diagram, the nuclear galaxy activity is classified such that 72% of the galaxies with emission are LINERs, 9% are Seyferts, 12% are composite/transition objects, and 7% are non-classified. Seyferts have young luminostiy-weighted ages (≲5 Gyr), and appear, on average, significantly younger than LINERs and composites. Excluding the Seyferts from our sample, we find that the spread in the ([OIII], Hα, or [NII]) emission strength increases with the galaxy central velocity dispersion σ_c. Furthermore, the [NII]/Hα ratio tends to increase with σ_c. The [NII]/Hα ratio decreases with increasing galactocentric distance, indicative of either a decrease in the nebular metallicity, or a progressive “softening” of the ionizing spectrum. The average nebular oxygen abundance is slightly less than solar, and a comparison with the results obtained in Paper III from Lick indices shows that it is ≈0.2 dex lower than that of stars. Conclusions: The nuclear (r < re/16) emission can be attributed to photoionization

  17. A Three Dimensional Beam Profile Monitor Based on Residual Gas Ionization

    SciTech Connect

    Lewis, T.A.; Shapira, D.

    1998-11-04

    A three-dimensional beam profile monitor based on tracking the ionization of the residual gas molecules in the evacuated beam pipe is described. Tracking in position and time of the ions and electrons produced in the ionization enables simultaneous position sampling in three dimensions. Special features which make it possible to sample very low beam currents were employed.

  18. Evaluation of Gas-filled Ionization Chamber Method for Radon Measurement at Two Reference Facilities

    SciTech Connect

    Ishikawa, Tetsuo; Tokonami, Shinji; Kobayashi, Yosuke; Sorimachi, Atsuyuki; Yatabe, Yoshinori; Miyahara, Nobuyuki

    2008-08-07

    For quality assurance, gas-filled ionization chamber method was tested at two reference facilities for radon calibration: EML (USA) and PTB (Germany). Consequently, the radon concentrations estimated by the ionization chamber method were in good agreement with the reference radon concentrations provided by EML as well as PTB.

  19. Infrared spectroscopy of ionized corannulene in the gas phase

    NASA Astrophysics Data System (ADS)

    Galué, Héctor Alvaro; Rice, Corey A.; Steill, Jeffrey D.; Oomens, Jos

    2011-02-01

    The gas-phase infrared spectra of radical cationic and protonated corannulene were recorded by infrared multiple-photon dissociation (IRMPD) spectroscopy using the IR free electron laser for infrared experiments. Electrospray ionization was used to generate protonated corannulene and an IRMPD spectrum was recorded in a Fourier-transform ion cyclotron resonance mass spectrometer monitoring H-loss as a function of IR frequency. The radical cation was produced by 193-nm UV photoionization of the vapor of corannulene in a 3D quadrupole trap and IR irradiation produces H, H2, and C2Hx losses. Summing the spectral response of the three fragmentation channels yields the IRMPD spectrum of the radical cation. The spectra were analyzed with the aid of quantum-chemical calculations carried out at various levels of theory. The good agreement of theoretical and experimental spectra for protonated corannulene indicates that protonation occurs on one of the peripheral C-atoms, forming an sp3 hybridized carbon. The spectrum of the radical cation was examined taking into account distortions of the C5v geometry induced by the Jahn-Teller effect as a consequence of the degenerate 2E1 ground electronic state. As indicated by the calculations, the five equivalent Cs minima are separated by marginal barriers, giving rise to a dynamically distorted system. Although in general the character of the various computed vibrational bands appears to be in order, only a qualitative match to the experimental spectrum is found. Along with a general redshift of the calculated frequencies, the IR intensities of modes in the 1000-1250 cm-1 region show the largest discrepancy with the harmonic predictions. In addition to CH "in-plane" bending vibrations, these modes also exhibit substantial deformation of the pentagonal inner ring, which may relate directly to the vibronic interaction in the radical cation.

  20. Analysis of polyaromatic hydrocarbon mixtures with laser ionization gas chromatography/mass spectrometry

    SciTech Connect

    Rhodes, G.; Opsal, R.B.; Meek, J.T.; Reilly, J.P.

    1983-02-01

    Excimer laser induced multiphoton ionization has been utilized for ion generation in capillary gas chromatography/mass spectrometry and the technique applied to the separation and detection of polyaromatic hydrocarbons. Detection limits as low as 200 fg and linearity over a range of 5 x 10/sup +4/ were obtained for the polyaromatic hydrocarbons examined. Multiphoton ionization mass spectra were dominated by parent ions. Selective ionization based upon small differences in ionization potentials has been demonstrated for coeluting chrysene and triphenylene. Instrumental parameters have been investigated to assess improvements in sensitivity.

  1. Influence of ionization on ultrafast gas-based nonlinear fiber optics.

    PubMed

    Chang, W; Nazarkin, A; Travers, J C; Nold, J; Hölzer, P; Joly, N Y; Russell, P St J

    2011-10-10

    We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

  2. Cosmic ray studies with a gas Cherenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Yodh, G. B.; Simon, M.; Spiegelhauer, H.

    1980-01-01

    The results from a balloon-borne gas Cherenkov counter (threshold 16.5 GeV/nucleon) and an ionization spectrometer are presented. The gas Cherenkov counter provides an absolute energy distribution for the response of the calorimeter for 5 or = Z 26 nuclei of cosmic rays. The contribution of scintillation to the gas Cherenkov pulse height was obtained by independently selecting particles below the gas Cherenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi squared between Monte Carlo simulted data and flight data. Best fit power laws, dN/dE = AE-gamma, were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E (-2.7) are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer. The data from the ionization calorimeter and the gas Cherenkov are thus completely self-consistent.

  3. Shock Structure Analysis and Aerodynamics in a Weakly Ionized Gas Flow

    NASA Technical Reports Server (NTRS)

    Saeks, R.; Popovic, S.; Chow, A. S.

    2006-01-01

    The structure of a shock wave propagating through a weakly ionized gas is analyzed using an electrofluid dynamics model composed of classical conservation laws and Gauss Law. A viscosity model is included to correctly model the spatial scale of the shock structure, and quasi-neutrality is not assumed. A detailed analysis of the structure of a shock wave propagating in a weakly ionized gas is presented, together with a discussion of the physics underlying the key features of the shock structure. A model for the flow behind a shock wave propagating through a weakly ionized gas is developed and used to analyze the effect of the ionization on the aerodynamics and performance of a two-dimensional hypersonic lifting body.

  4. Mass spectrometric behavior of anabolic androgenic steroids using gas chromatography coupled to atmospheric pressure chemical ionization source. Part I: ionization.

    PubMed

    Raro, M; Portolés, T; Sancho, J V; Pitarch, E; Hernández, F; Marcos, J; Ventura, R; Gómez, C; Segura, J; Pozo, O J

    2014-06-01

    The detection of anabolic androgenic steroids (AAS) is one of the most important topics in doping control analysis. Gas chromatography coupled to (tandem) mass spectrometry (GC-MS(/MS)) with electron ionization and liquid chromatography coupled to tandem mass spectrometry have been traditionally applied for this purpose. However, both approaches still have important limitations, and, therefore, detection of all AAS is currently afforded by the combination of these strategies. Alternative ionization techniques can minimize these drawbacks and help in the implementation of a single method for the detection of AAS. In the present work, a new atmospheric pressure chemical ionization (APCI) source commercialized for gas chromatography coupled to a quadrupole time-of-flight analyzer has been tested to evaluate the ionization of 60 model AAS. Underivatized and trimethylsylil (TMS)-derivatized compounds have been investigated. The use of GC-APCI-MS allowed for the ionization of all AAS assayed irrespective of their structure. The presence of water in the source as modifier promoted the formation of protonated molecules ([M+H](+)), becoming the base peak of the spectrum for the majority of studied compounds. Under these conditions, [M+H](+), [M+H-H2O](+) and [M+H-2·H2O](+) for underivatized AAS and [M+H](+), [M+H-TMSOH](+) and [M+H-2·TMSOH](+) for TMS-derivatized AAS were observed as main ions in the spectra. The formed ions preserve the intact steroid skeleton, and, therefore, they might be used as specific precursors in MS/MS-based methods. Additionally, a relationship between the relative abundance of these ions and the AAS structure has been established. This relationship might be useful in the structural elucidation of unknown metabolites.

  5. The ionization conditions in the Milky Way halo - Infalling gas toward the North Galactic Pole

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1992-01-01

    Observations of gas in the Milky Way halo are studied with an eye toward the theoretical predictions of the Galactic Fountain model for the production of halo gas. Data are shown that indicate significant variations in the ionization conditions in infalling halo gas in the northern galactic hemisphere. Understanding the nature of Milky Way halo gas plays a critical role in interpreting QSO absorption lines in the investigation of galaxies at high redshift.

  6. Hot interstellar gas and ionization of embedded clouds

    NASA Technical Reports Server (NTRS)

    Cheng, K.-P.; Bruhweiler, F.

    1990-01-01

    Researchers present detailed photoionization calculations for the instellar cloud in which the Sun is embedded. They consider the EUV radiation field with contribution from discrete stellar sources and from a thermal bremsstrahlung-radiative recombination spectrum emitted from the surrounding 10 to the 6th power k coronal substrate. They establish lower limits to the fractional ionization of hydrogen and helium of 0.17 and 0.29 respectively. The high He ionization fraction results primarily from very strong line emission below 500 A originating in the surrounding coronal substrate while the H ionization is dominated by the EUV radiation from the discrete stellar sources. The dual effects of thermal conduction and the EUV spectrum of the 10 to the 6th k plasma on ionization in the cloud skin are explored. The EUV radiation field and Auger ionization have insignificant effects on the resulting ionic column densities of Si IV, C IV, N V and O VI through the cloud skin. Calculations show that the abundances of these species are dominated by collisional ionization in the thermal conduction front. Because of a low charge exchange rate with hydrogen, the ionic column density ratios of N (CIII)/N (CII) and N (NII)/N (NI) are dominated by the EUV radiation field in the local interstellar medium. These ratios should be important diagnostics for the EUV radiation field and serve as surrogate indicators of the interstellar He and H ionization fraction respectively. Spacecraft such as Lyman which is designed to obtain high resolution spectral data down to the Lyman limit at 912 A could sample interstellar lines of these ions.

  7. Nonlinear optical response of multiply ionized noble-gas atoms

    NASA Astrophysics Data System (ADS)

    Tarazkar(1, 3), Maryam; Romanov(2, 3), Dmitri; Levis(1, 3), Robert

    2016-05-01

    Calculation of dynamic polarizabilities and hyperpolarizabilities of ionized species using ab initio methods presents computational and conceptual difficulties, as these ionized species often have open-shell electronic system. We use multi-configurational self-consistent field (MCSCF) method with extended basis sets for calculating dynamic polarizability and second-order hyperpolarizabilities of atomic noble gases and their multiply charged cations in non-resonant regime. The calculations were performed at wavelengths ranging from about 100 nm to the red of the first multi-photon resonance all the way toward the static regime. The results were benchmarked to those of CCSD calculations for ions of even-number charge. The second-order hyperpolarizability coefficients were found to decrease when the electrons are progressively removed from the system. At higher ionization states, these coefficients become less dispersive as a function of wavelength. The values and even the signs of the γ (2) coefficients were found to depend on the spin of the ionic quantum state. Thus, for Ne+3 and Ne+4, in low-spin states (2 Pu, and 1 Sg, respectively) the sign of γ (2) is positive, whereas in high-spin states (4 Su, and 3 Pg) the sign is negative. The calculated hyperpolarizabilities of multiply ionized atoms relate to experiments on very bright high-order harmonic generation in multiply ionized plasmas.

  8. The kinematics of Milky Way halo gas. I - Observations of low-ionization species

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1989-01-01

    Ultraviolet interstellar line day observed with the IUE toward 70 halo stars and four extragalactic sight lines are analyzed in a study of the large-scale kinematic properties of the Milky Way halo gas. The motions of the low-ionization gas is focused on. Large systematic velocities are found, and a pronounced asymmetry in the absorption characteristics of halo gas toward the Galactic poles is indicated. In the north, substantial amounts of material are falling toward the disk at velocities up to about 120 km/s in the most extreme case. Toward the south, low-ionization material shows no extreme or systematic motions.

  9. Surface Ionization Gas Detection at SnO{sub 2} Surfaces

    SciTech Connect

    Krenkow, A.; Oberhuettinger, C.; Habauzit, A.; Kessler, M.; Goebel, J.; Mueller, G.

    2009-05-23

    In surface ionization (SI) gas detection adsorbed analyte molecules are converted into ionic species at a heated solid surface and extracted into free space by an oppositely biased counter electrode. In the present work we consider the formation of positive and negative analyte gas ions at SnO{sub 2} surfaces. We find that SI leads to positive ion formation only, with the SI efficiency scaling with the ionization energy of the analyte gas molecules. Aromatic and aliphatic hydrocarbons with amine functional groups exhibit particularly high SI efficiencies.

  10. Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation

    NASA Technical Reports Server (NTRS)

    Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)

    2002-01-01

    This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.

  11. Investigating the Diffuse Ionized Gas in the Magellanic Stream with Mapped WHAM Observations

    NASA Astrophysics Data System (ADS)

    Smart, Brianna; Haffner, L. Matthew; Barger, Kathleen; Hernandez, Mike

    2016-01-01

    We present early stages of an Hα survey of the Magellanic Stream using the Wisconsin H-Alpha Mapper (WHAM). While the neutral component of the Stream may extend 200° across the sky (Nidever et al. 2010), its ionized gas has not yet been studied in detail. Fox et al. 2014 find that the tidal debris in the Magellanic System contains twice as much ionized gas as neutral and may extend 30° away from the H I emission. However, such absorption-line studies are not sensitive to the overall morphology of the ionized gas. Using targeted Hα emission observations of the Magellanic Stream, Barger et al. 2015 find that although the warm ionized gas tracks the neutral gas, it often spans a few degrees away from the H I emission at slightly offset velocities. Using WHAM's unprecedented sensitivity to diffuse emission (~ 10s of mR) and its velocity resolution (12 km/s) to isolate Stream emission, we are now conducting the first full Hα survey of its ionized component. Here we present early results, including spatial and kinematic comparisons to the well-established neutral profile of the Stream. WHAM research and operations are supported through NSF Award AST-1108911.

  12. The Massive Stellar Population in the Diffuse Ionized Gas of M33

    NASA Technical Reports Server (NTRS)

    Hoopes, Charles G.; Walterbos, Rene A. M.

    1995-01-01

    We compare Far-UV, H alpha, and optical broadband images of the nearby spiral galaxy M33, to investigate the massive stars associated with the diffuse ionized gas. The H-alpha/FUV ratio is higher in HII regions than in the DIG, possibly indicating that an older population ionizes the DIG. The broad-band colors support this conclusion. The HII region population is consistent with a young burst, while the DIG colors resemble an older population with constant star formation. Our results indicate that there may be enough massive field stars to ionize the DIG, without the need for photon leakage from HII regions.

  13. Gas-phase chemiluminescence and chemi-ionization

    SciTech Connect

    Fontijn, A.

    1985-01-01

    The phenomena of chemiluminescence (or more broadly chemi-excitation) and chemi-ionization have major similarities from a fundamental kinetic and dynamic point of view. However, since the former has primarily been investigated using optical spectroscopic techniques and the latter largely by mass spectroscopic (and other gaseous electronic) methods, the two phenomena have apparently never, explicitly been discussed together in one volume. In addition to a number of review articles on each individual subject, several meetings and books have had chemiluminescence and bioluminescence as their theme and those have been dominated by condensed phase work. On the other hand, chemi-ionization is often discussed in the contest of gaseous electronics, plasma chemistry and combustion. It is the goal of this book to present a more unified understanding of the two phenomena.

  14. Ionized gas characteristics in the cavities of the gas and dust disc of the spiral galaxy NGC 6946

    NASA Astrophysics Data System (ADS)

    Efremov, Yu. N.; Afanasiev, V. L.; Egorov, O. V.

    2011-07-01

    The parameters of the ionized gas in NGC 6946 (in the [NII] λλ6548, 6583, H α and [SII] λλ6717, 6731 lines) are investigated with the SAO RAS BTA telescope along three positions of the long slit of the SCORPIO focal reducer, passing through a number of large and small cavities of the gaseous disc of the galaxy. These cavities correspond exactly to the cavities in warm dust, visible at 5 - 8µm. We found that everywhere in the direction of NGC 6946 the lines of ionized gas are decomposed into two Gaussians, one of which shows almost constant [SII]/H α and [NII]/H α ratios, as well as an almost constant radial velocity within the measurement errors (about -35… - 50 km/s). This component is in fact the foreground radiation from the diffuse ionized gas of our Galaxy, which is not surprising, given the low (12°) latitude of NGC 6946; a similar component is also present in the emission of neutral hydrogen. The analysis of the component of ionized gas, occurring inNGC 6946, has revealed that it shows signs of shock excitation in the cavities of the gaseous disc of the galaxy. This shock excitation is as well typical for the extraplanar diffuse ionized gas (EDIG), observed in a number of spiral galaxies at their high Z-coordinates. This can most likely be explained by low density of the gas in the NGC 6946 disc (with the usual photoionization) inside the cavities, due to what we see the spectral features of the EDIG gas of NGC 6946, projected onto them, and located outside the plane of the galaxy. In the absence of separation of ionized gas into two components by radial velocities, there is an increasing contribution to the integral line parameters by the EDIG of our Galaxy when the gas density in NGC 6946 decreases, which explains some strange results, obtained in the previous studies. Themorphology of warmdust, visible in the infrared range and HI is almost the same (except for the peripheral parts of the galaxy, where there are no sources of dust heating

  15. Black hole mass measurements using ionized gas discs: systematic dust effects

    SciTech Connect

    Baes, Maarten

    2008-10-08

    Using detailed Monte Carlo radiative transfer simulations in realistic models for galactic nuclei, we investigate the influence of interstellar dust in ionized gas discs on the rotation curves and the resulting black hole mass measurements. We find that absorption and scattering by interstellar dust leaves the shape of the rotation curves basically unaltered, but slightly decreases the central slope of the rotation curves. As a result, the ''observed'' black hole masses are systematically underestimated by some 10 to 20% for realistic optical depths. We therefore argue that the systematic effect of dust attenuation should be taken into account when estimating SMBH masses using ionized gas kinematics.

  16. Observational model of the ionized gas in Seyfert and radio-galaxy nuclei*

    PubMed Central

    Osterbrock, Donald E.

    1978-01-01

    Equivalent widths of the total emission-line Hβ in Seyfert 1, Seyfert 2, and intermediate-type Seyfert galaxies, expressed in terms of the featureless continuum, all have approximately the same frequency distribution. This suggests that the energy-input mechanism to both the narrow-line, low-density gas and the broad-line, high-density gas is photoionization by the featureless continuum. The reason for the weakness of the narrow emission lines in extreme Seyfert 1 galaxies is then the absorption of most of the ionizing photons in the dense gas near the central source. The statistics of line widths can be fitted by a model in which the dense gas has typical rotational velocity 5000 km/sec and typical turbulent velocity 2000 km/sec. A model is proposed in which the dense gas forms a rotating, turbulent disk with dimension ≈0.1 pc and height/diameter ≈2/5. Seyfert 2 galaxies are objects with little dense gas, and intermediate-type Seyfert galaxies are objects in which the dense gas is optically thin to ionizing radiation at least along the poles. Most radio galaxies have strong narrow emission lines, suggesting that escape of radio plasma can only occur where some ionizing photons can also escape from the dense gas. Other predictions, implications, and tests of this model are discussed. Images PMID:16592488

  17. Study of the surface ionization detector for gas chromatography.

    PubMed

    Li, Weiwei; Wu, Dapeng; Chen, Shiheng; Peng, Hong; Guan, Yafeng

    2011-09-23

    The structure of the surface ionization detector (SID) and the operation parameters of GC-SID were investigated to reduce peak tailing and to enhance sensitivity. The performances of the GC-SID, including its repeatability, linearity, sensitivity, selectivity, and tolerance towards water vapor, were evaluated systematically. Compared with nitrogen-phosphorus detector (NPD), the SID was able to detect fg level triethylamine, and selectively respond to alkylamines, some anilines, and some nitrogen heterocyclic compounds. Among alkylamines, the SID sensitivity to diisobutylamine was rather small. Even so, it was also still 10 times higher than that on NPD. The SID selectivity, defined as the sensitivity ratio between triethylamine and various tested non-nitrogen compounds, was higher than 10(6). It was found that the SID is highly tolerant towards water vapor, allowing direct injection of water sample. Finally, the GC-SID was applied to directly measure trace amines in headspace gases of rotted meat and trace simazine in tap water. The SID sensitivity to simazine was proven to be 5 times higher than that on flame ionization detector (FID). This study suggests that the SID is a promising GC detector. PMID:21839459

  18. Determination of Hexachlorocyclohexane by Gas Chromatography Combined with Femtosecond Laser Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Yang, Xixiang; Imasaka, Tomoko; Li, Adan; Imasaka, Totaro

    2016-09-01

    Structural isomers and enantiomers of hexachlorocyclohexane (HCH) were separated using a chiral column by gas chromatography and quantitatively determined by multiphoton ionization mass spectrometry using an ultraviolet femtosecond laser (200 and 267 nm) as the ionization source. The order of elution of the enantiomers (i.e., (+)-α-HCH and (-)-α-HCH) was predicted from stabilization energies calculated for the complexes using permethylated γ-cyclodextrin as the stationary phase of the column, and the results were compared with the experimental data. The molecular ions observed for HCH were weak, even though they can be ionized through a process of resonance enhanced two-photon ionization at 200 nm. This unfavorable result can be attributed to the dissociation of the molecular ion, as predicted from quantum chemical calculations.

  19. Cosmic ray studies with a gas Cerenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Simon, M.; Spiegelhauer, H.; Yodh, G. B.

    1980-01-01

    The results from a balloon-borne gas Cerenkov counter (threshold 16.5 GeV/nuc) and an ionization spectrometer are presented. The gas Cerenkov counter provides an absolute energy calibration for the response of the calorimeter for the Z range of 5-26 nuclei of cosmic rays. The contribution of scintillation to the gas Cerenkov pulse height has been obtained by independently selecting particles below the gas Cerenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi-squared between a Monte Carlo simulated data and flight data. Best fit power laws were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E exp-2.7, are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer.

  20. Ammonia quantitative analysis model based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model

    PubMed Central

    Ma, Rongfei

    2015-01-01

    In this paper, ammonia quantitative analysis based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model was proposed. Al plate anodic gas-ionization sensor was used to obtain the current-voltage (I-V) data. Measurement data was processed by non-linear bistable dynamics model. Results showed that the proposed method quantitatively determined ammonia concentrations. PMID:25975362

  1. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  2. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  3. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  4. Field ionization kinetic and electron impact studies of gas phase transition states - The cyclic bromonium ion

    NASA Technical Reports Server (NTRS)

    Green, M. M.; Giguere, R. J.; Falick, A. M.; Aberth, W.; Burlingame, A. L.

    1978-01-01

    Cis- and trans-isomers of 4-t-butylcyclohexyl bromide were studied to determine the mechanism of cyclic bromonium ion formation. The field ionization kinetic and electron impact data indicate that the formation of the cyclic structure occurs simultaneously with loss of the neutral fragment. The data also show that little or no gas-phase cis-trans isomerization occurs.

  5. Noble Gas Detection Using Resonance Ionization Spectroscopy and a Quadrupole Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Hurst, G. S.

    1983-10-01

    The technique of Resonance Ionization Spectroscopy (RIS) is being extended to develop a means for counting individual atoms of a selected isotope of a noble gas. In this method, lasers are used for RIS to obtain atomic species (Z) selectivity and a small quadrupole mass spectrometer provides isotopic (A) selectivity. A progress report on the objective of counting each atom of a particular isotope of a noble gas is given. Resonance ionization spectroscopy and its use for the detection of single atoms has been reviewed.' More recently, our efforts at ORNL have turned to the problem of direct counting of noble gas atoms2,3,4 as an alternative to decay counting of particular isotopes of noble gas species. For broader applications, the ORNL group is trying to develop a facility for counting a few rare gas atoms of a given isotopic variety in a sample. The detection of a small number of 81Kr atoms (<1000) is very important for groundwater dating, polar ice-cap dating, and nuclear waste disposal applications, and solar neutrino research. The ultimate goal is to count a small number (e.g., 100 to 1,000) of selected atoms having mass number A, even when mixed with 1012 or more atoms having mass number ± 1. The experimental schematic is shown in Figure 1. The concept for counting noble gas atoms with isotopic selectivity is to utilize a laser for ionizing atoms of a selected atomic

  6. Dust and ionized gas in active radio elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Forbes, D. A.; Sparks, W. B.; Macchetto, F. D.

    1990-01-01

    The authors present broad and narrow bandwidth imaging of three southern elliptical galaxies which have flat-spectrum active radio cores (NGC 1052, IC 1459 and NGC 6958). All three contain dust and extended low excitation optical line emission, particularly extensive in the case of NGC 1052 which has a large H alpha + (NII) luminosity. Both NGC 1052 and IC 1459 have a spiral morphology in emission-line images. All three display independent strong evidence that a merger or infall event has recently occurred, i.e., extensive and infalling HI gas in NGC 1052, a counter-rotating core in IC 1459 and Malin-Carter shells in NGC 6958. This infall event is the most likely origin for the emission-line gas and dust, and the authors are currently investigating possible excitation mechanisms (Sparks et al. 1990).

  7. Dissociation and ionization of molecular gas in the spiral arms of M51

    NASA Technical Reports Server (NTRS)

    Lees, J. F.; Lo, K. Y.

    1990-01-01

    Researchers derive the star formation rate and efficiency in the arm and interarm regions of M51 from observations of the molecular (Lo et al. 1987) and ionized (van der Hulst et al. 1988) phases of the interstellar medium, and show that the HI observations of Tilanus and Allen (1989) are consistent with dissociation of molecular gas by these young, massive stars if n sub H greater than or equal to 200 cm (-2). However, these stars are not able to dissociate or ionize all the gas, and at least 60 percent must remain molecular in the interarm regions. The efficiency of star formation in M51 seems to be similar to that in the Galaxy, and does not appear to be enhanced in the spiral arms. Therefore, the effect of the strong density wave may be only to concentrate the gas, and hence the young stars, to the arm regions.

  8. IONIZED GAS IN THE FIRST 10 kpc OF THE INTERSTELLAR GALACTIC HALO: METAL ION FRACTIONS

    SciTech Connect

    Howk, J. Christopher; Consiglio, S. Michelle E-mail: smconsiglio@ucla.edu

    2012-11-10

    We present direct measures of the ionization fractions of several sulfur ions in the Galactic warm ionized medium (WIM). We obtained high-resolution ultraviolet absorption-line spectroscopy of post-asymptotic giant branch stars in the globular clusters Messier 3 [(l, b) = (42.{sup 0}2, +78.{sup 0}7), d = 10.2 kpc, and z = 10.0 kpc] and Messier 5 [(l, b) = (3.{sup 0}9, +46.{sup 0}8), d = 7.5 kpc, and z = +5.3 kpc] with the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer to measure, or place limits on, the column densities of S I, S II, S III, S IV, S VI, and H I. These clusters also house millisecond pulsars, whose dispersion measures give an electron column density from which we infer the H II column in these directions. We find fractions of S{sup +2} in the WIM for the M 3 and M 5 sight lines x(S{sup +2}) {identical_to} N(S{sup +2})/N(S) = 0.33 {+-} 0.07 and 0.47 {+-} 0.09, respectively, with variations perhaps related to location. With negligible quantities of the higher ionization states, we conclude that S{sup +} and S{sup +2} account for all of the S in the WIM. We extend the methodology to study the ion fractions in the warm and hot ionized gas of the Milky Way, including the high ions Si{sup +3}, C{sup +3}, N{sup +4}, and O{sup +5}. The vast majority of the Galactic ionized gas is warm (T {approx} 10{sup 4} K) and photoionized (the WIM) or very hot (T > 4 Multiplication-Sign 10{sup 5} K) and collisionally ionized. The common tracer of ionized gas beyond the Milky Way, O{sup +5}, traces <1% of the total ionized gas mass of the Milky Way.

  9. Hose Instability and Wake Generation By An Intense Electron Beam in a Self-Ionized Gas

    SciTech Connect

    Deng, S.; Barnes, C.D.; Clayton, C.E.; O'Connell, C.; Decker, F.J.; Fonseca, R.A.; Huang, C.; Hogan, M.J.; Iverson, R.; Johnson, D.K.; Joshi, C.; Katsouleas, T.; Krejcik, P.; Lu, W.; Mori, W.B.; Muggli, P.; Oz, E.; Tsung, F.; Walz, D.; Zhou, M.; /Southern California U. /UCLA /SLAC

    2006-04-12

    The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.

  10. Hose instability and wake generation by an intense electron beam in a self-ionized gas.

    PubMed

    Deng, S; Barnes, C D; Clayton, C E; O'Connell, C; Decker, F J; Fonseca, R A; Huang, C; Hogan, M J; Iverson, R; Johnson, D K; Joshi, C; Katsouleas, T; Krejcik, P; Lu, W; Mori, W B; Muggli, P; Oz, E; Tsung, F; Walz, D; Zhou, M

    2006-02-01

    The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.

  11. Isobutane Made Practical as a Reagent Gas for Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Newsome, G. Asher; Steinkamp, F. Lucus; Giordano, Braden C.

    2016-11-01

    As a reagent gas for positive- and negative-mode chemical ionization mass spectrometry (CI-MS), isobutane ( i-C4H10) produces superior analyte signal abundance to methane. Isobutane has never been widely adopted for CI-MS because it fouls the ion source more rapidly and produces positive CI spectra that are more strongly dependent on reagent gas pressure compared with methane. Isobutane was diluted to various concentrations in argon for use as a reagent gas with an unmodified commercial gas chromatograph-mass spectrometer. Analyte spectra were directly compared using methane, isobutane, and isobutane/argon mixtures. A mixture of 10% i-C4H10 in argon produced twice the positive-mode analyte signal of methane, equal to pure isobutane, and reduced spectral dependence on reagent gas pressure. Electron capture negative chemical ionization using 1% i-C4H10 in argon tripled analyte signal compared with methane and was reproducible, unlike pure isobutane. The operative lifetime of the ion source using isobutane/argon mixtures was extended exponentially compared with pure isobutane, producing stable and reproducible CI signal throughout. By diluting the reagent gas in an inert buffer gas, isobutane CI-MS experiments were made as practical to use as methane CI-MS experiments but with superior analytical performance.

  12. Isobutane Made Practical as a Reagent Gas for Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Newsome, G. Asher; Steinkamp, F. Lucus; Giordano, Braden C.

    2016-08-01

    As a reagent gas for positive- and negative-mode chemical ionization mass spectrometry (CI-MS), isobutane (i-C4H10) produces superior analyte signal abundance to methane. Isobutane has never been widely adopted for CI-MS because it fouls the ion source more rapidly and produces positive CI spectra that are more strongly dependent on reagent gas pressure compared with methane. Isobutane was diluted to various concentrations in argon for use as a reagent gas with an unmodified commercial gas chromatograph-mass spectrometer. Analyte spectra were directly compared using methane, isobutane, and isobutane/argon mixtures. A mixture of 10% i-C4H10 in argon produced twice the positive-mode analyte signal of methane, equal to pure isobutane, and reduced spectral dependence on reagent gas pressure. Electron capture negative chemical ionization using 1% i-C4H10 in argon tripled analyte signal compared with methane and was reproducible, unlike pure isobutane. The operative lifetime of the ion source using isobutane/argon mixtures was extended exponentially compared with pure isobutane, producing stable and reproducible CI signal throughout. By diluting the reagent gas in an inert buffer gas, isobutane CI-MS experiments were made as practical to use as methane CI-MS experiments but with superior analytical performance.

  13. Role of gas dynamics in negative ion formation in an atmospheric sampling glow discharge ionization source

    SciTech Connect

    Chambers, D.M.; McLuckey, S.A.; Glish, G.L. )

    1993-03-15

    A version of the atmospheric sampling glow discharge ionization (ASGDI) source was developed to study the role of gas dynamics on anion formation. This source, which is used in conjunction with mass spectrometry for direct air monitoring, was designed so several key instrumental dimensions as well as operating parameters could be readily changed. Such flexibility permitted the study of ionization processes in ASGDI and the parameters that can be controlled to favor a particular ion product. One aspect of ASGDI that was found to influence ionization yield was the hydrodynamic properties of the sample inlet free-jet expansion. From these investigations, it was found that mean molecular flow of species expanding toward the skimmer could be manipulated to favor kinetically fast reactions over more thermodynamically preferred reactions. In the case of 2,4-dinitrotoluene, observation of the M[sup [minus

  14. In-gas-cell laser ionization studies of plutonium isotopes at IGISOL

    NASA Astrophysics Data System (ADS)

    Pohjalainen, I.; Moore, I. D.; Kron, T.; Raeder, S.; Sonnenschein, V.; Tomita, H.; Trautmann, N.; Voss, A.; Wendt, K.

    2016-06-01

    In-gas-cell resonance laser ionization has been performed on long-lived isotopes of Pu at the IGISOL facility, Jyväskylä. This initiates a new programme of research towards high-resolution optical spectroscopy of heavy actinide elements which can be produced in sufficient quantities at research reactors and transported to facilities elsewhere. In this work a new gas cell has been constructed for fast extraction of laser-ionized elements. Samples of 238-240,242Pu and 244Pu have been evaporated from Ta filaments, laser ionized, mass separated and delivered to the collinear laser spectroscopy station. Here we report on the performance of the gas cell through studies of the mass spectra obtained in helium and argon, before and after the radiofrequency quadrupole cooler-buncher. This provides valuable insight into the gas phase chemistry exhibited by Pu, which has been additionally supported by measurements of ion time profiles. The resulting monoatomic yields are sufficient for collinear laser spectroscopy. A gamma-ray spectroscopic analysis of the Pu samples shows a good agreement with the assay provided by the Mainz Nuclear Chemistry department.

  15. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies.

    PubMed

    Vessecchi, Ricardo; Naal, Zeki; Lopes, José N C; Galembeck, Sérgio E; Lopes, Norberto P

    2011-06-01

    Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses. PMID:21561138

  16. Determination of polybrominated biphenyls in Tasmanian devils (Sarcophilus harrisii) by gas chromatography coupled to electron capture negative ion tandem mass spectrometry or electron ionization high-resolution mass spectrometry.

    PubMed

    Vetter, Walter; Recke, Roland von der; Symons, Robert; Pyecroft, Stephen

    2008-12-01

    Two gas chromatography/mass spectrometry (GC/MS) methods for the determination of polybrominated biphenyls (PBBs) by isotope dilution analysis (IDA) using (13)C(12)-PBB 153 in the presence of polybrominated diphenyl ethers (PBDEs) were compared. Recovery of (13)C(12)-PBB 153 which was added to the extracted lipids before sample purification was commenced ranged from 88-117% (mean value 98.2 +/- 8.9%). Nevertheless, IDA analysis of PBBs using (13)C(12)-labelled congeners is limited by the potential co-elution of PBBs with polybrominated diphenyl ethers (PBDEs). The pair PBB 153 and BDE 154 was inspected since M(+) and [M-2Br](+) ions of (13)C(12)-PBB 153 and BDE 154 were only separated by 4 u. Gas chromatography/electron ionization high-resolution mass spectrometry with selected ion monitoring (GC/EI-HRMS-SIM) was suitable when m/z 475.7449 and m/z 477.7429 were used for (13)C(12)-PBB 153 because they are below the monoisotopic peak of the [M-2Br](+) fragment ion of hexaBDEs at m/z 479.7. Gas chromatography/electron capture negative ion tandem mass spectrometry selected reaction monitoring (GC/ECNI-MS/MS-SRM) measurements could be applied because (13)C(12)-PBB 153 and BDE 154 were separated by GC on a 25-m Factor Four CP-Sil 8MS column.Comparative measurements with GC/EI-HRMS-SIM and GC/ECNI-MSMS-SRM were carried out with samples of Tasmanian devils from Tasmania (Australia), an endangered species due to a virus epidemy which has already proved fatal for half of the population. Both techniques verified concentrations of PBB 153 in the range 0.3-11 ng/g lipids with excellent agreement of the levels in all but two samples. The PBB residue pattern demonstrated that PBB pollution originated from the previous discharge with technical hexabromobiphenyl which is dominated by PBB 153. Other congeners such as PBB 132 and PBB 138 were detected in the Tasmanian devils but the proportions relative to PBB 153 were lower than in the technical product. Samples of healthy and

  17. Chemical Abundances and Properties of the Ionized Gas in NGC 1705

    NASA Astrophysics Data System (ADS)

    Annibali, F.; Tosi, M.; Pasquali, A.; Aloisi, A.; Mignoli, M.; Romano, D.

    2015-11-01

    We obtained [O iii] narrow-band imaging and multi-slit MXU spectroscopy of the blue compact dwarf (BCD) galaxy NGC 1705 with FORS2@VLT to derive chemical abundances of planetary nebulae and H ii regions and, more in general, to characterize the properties of the ionized gas. The auroral [O iii]λ 4363 line was detected in all but 1 of the 11 analyzed regions, allowing for a direct estimate of their electron temperature. The only object for which the [O iii]λ 4363 line was not detected is a possible low-ionization PN, the only one detected in our data. For all the other regions, we derived the abundances of nitrogen, oxygen, neon, sulfur, and argon out to ˜1 kpc from the galaxy center. We detect for the first time in NGC 1705 a negative radial gradient in the oxygen metallicity of -0.24+/- 0.08 dex kpc-1. The element abundances are all consistent with values reported in the literature for other samples of dwarf irregular and BCD galaxies. However, the average (central) oxygen abundance, 12+{log}({{O}}/{{H}})=7.96+/- 0.04, is ˜0.26 dex lower than previous literature estimates for NGC 1705 based on the [O iii]λ 4363 line. From classical emission line diagnostic diagrams, we exclude a major contribution from shock excitation. On the other hand, the radial behavior of the emission line ratios is consistent with the progressive dilution of radiation with increasing distance from the center of NGC 1705. This suggests that the strongest starburst located within the central ˜150 pc is responsible for the ionization of the gas out to at least ˜1 kpc. The gradual dilution of the radiation with increasing distance from the center reflects the gradual and continuous transition from the highly ionized H ii regions in the proximity of the major starburst into the diffuse ionized gas.

  18. STS-39 Critical Ionization Velocity (CIV) gas release from OV-103 payload bay

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A plume of nitrous oxide gas is released from a compressed gas canister mounted on the increased capacity adaptive payload carrier 1 (ICAPC-1) on the forward port side of Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). The gas release is part of the Critical Ionization Velocity (CIV) experiment conducted during STS-39. The Shuttle Pallet Satellite II (SPAS-II) 'parked' about two kilometers (km) away, is taking infrared, visible, and ultraviolet radiometric spatial, spectral, and temporal measurements of the gas plumes. Surrounding the CIV ICAPC-1 are: the ICAPC-2 payload support subsystem, radiometer, and Langmuir probe also mounted on the port side; the Space Test Payload 1 (STP-1) multipurpose experiment support structure (MPESS) (just beyond gas beam); and the Air Force Program 675 (AFP-675) experiment support structure (ESS).

  19. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula.

    PubMed

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-06-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)-CO-N2-noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system.

  20. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula

    PubMed Central

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-01-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)−CO−N2−noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system. PMID:26039983

  1. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula.

    PubMed

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-06-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)-CO-N2-noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system. PMID:26039983

  2. Studies of Flow in Ionized Gas: Historical Perspective, Contemporary Experiments, and Applications

    SciTech Connect

    Popovic, S.; Vuskovic, L.

    2007-04-23

    Since the first observations that a very small ionized fraction (order of 1 ppm) could strongly affect the gas flow, numerous experiments with partially or fully wall-free discharges have demonstrated the dispersion of shock waves, the enhancement of lateral forces in the flow, the prospects of levitation, and other aerodynamic effects with vast potential of application. A review of physical effects and observations are given along with current status of their interpretation. Special attention will be given to the physical problems of energy efficiency in generating wall-free discharges and the phenomenology of filamentary discharges. Comments and case examples are given on the current status of availability of necessary data for modelling and simulation of the aerodynamic phenomena in weakly ionized gas.

  3. Investigating the Diffuse Ionized Gas throughout the Magellanic Cloud System with WHAM

    NASA Astrophysics Data System (ADS)

    Smart, Brianna; Haffner, L. Matthew; Barger, Kathleen; Madsen, Gregory J.; Hill, Alex S.

    2015-01-01

    We present early stages of an H-α survey of the Magellanic System using the Wisconsin H-α Mapper (WHAM). Our maps of the Small Magellanic Cloud, Large Magellanic Cloud, and Magellanic Bridge are the most sensitive kinematic maps of ionized gas throughout the System. With a velocity resolution of 12 km/s, WHAM observations can cleanly separate diffuse emission at Magellanic velocities from that of the Milky Way and terrestrial sources. These new maps of the SMC and LMC compliment observations of the Magellanic Bridge by Barger et al. (2013), who found H-alpha emission extending throughout and beyond the observed H I emission. Using WHAM's unprecedented sensitivity to the limit of atmospheric line confusion (~ 10s of mR), we find that ionized gas emission extends at least 5 degrees beyond the traditional boundary of the SMC when compared to recent deep-imaging surveys (e.g., MCELS; Smith et al. 2005). The diffuse ionized emission extent is similar to the neutral gas extent as traced by 21 cm. We present spectra comparing H I and H-alpha kinematic signatures throughout the emission region, which are dominated by galactic rotation. Multi-wavelength observations are also underway in [S II] and [N II] for the SMC and LMC. WHAM research and operations are supported through NSF Award AST-1108911.

  4. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    SciTech Connect

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  5. Fluctuations in microwave background radiation due to secondary ionization of the intergalactic gas in the universe

    NASA Technical Reports Server (NTRS)

    Sunyayev, R. A.

    1979-01-01

    Secondary heating and ionization of the intergalactic gas at redshifts z approximately 10-30 could lead to the large optical depth of the Universe for Thomson scattering and could smooth the primordial fluctuations formed at z approximately 1500. It is shown that the gas motions connected with the large scale density perturbations at z approximately 10-15 must lead to the generation of secondary fluctuations of microwave background. The contribution of the rich clusters of galaxies and young galaxies to the fluctuations of microwave background is also estimated.

  6. H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas

    NASA Astrophysics Data System (ADS)

    Chandar, Rupali

    2014-10-01

    We propose to obtain narrow-band, H-alpha observations for a significant subset of the star-forming, nearby galaxies recently targeted by the LEGUS treasury program (GO-13364). LEGUS is observing these galaxies in five broad-band filters: NUV, U, B, V, and I. The new H-alpha observations will reveal thousands of previously undetected HII regions, including those ionized by stellar clusters and single massive stars, allow us to measure their luminosities and sizes, and to separate discrete sources from diffuse ionized gas. We will use our narrow-band imaging survey to: (1) establish the connection between star and cluster formation, and determine the prevelance with which isolated massive stars form in different galaxies; (2) determine whether the initial cluster mass function is universal; (3) investigate the size evolution of ionized gas bubbles, and how this depends on cluster age and mass, as well as on local galactic conditions; and (4) place stringent limits on the leakage of ionizing photons from HII regions, and better understand how the interplay between properties of the ionizing source and the morphology of the HII region impacts leakage. The broad goal of this study is to better understand how feedback from massive stars affects the surrounding medium. Ultimately, the interplay between feedback and the ISM on these scales will enable a better understanding of galaxy-scale outflows in the early universe, a process critical to galaxy evolution. This program naturally lends itself to an improvement of the scientific output by involving the general public via an already established Citizen Science program.

  7. INTEGRAL-FIELD STELLAR AND IONIZED GAS KINEMATICS OF PECULIAR VIRGO CLUSTER SPIRAL GALAXIES

    SciTech Connect

    Cortés, Juan R.; Hardy, Eduardo; Kenney, Jeffrey D. P. E-mail: ehardy@nrao.cl

    2015-01-01

    We present the stellar and ionized gas kinematics of 13 bright peculiar Virgo cluster galaxies observed with the DensePak Integral Field Unit at the WIYN 3.5 m telescope in order to look for kinematic evidence that these galaxies have experienced gravitational interactions or gas stripping. Two-dimensional maps of the stellar velocity V, stellar velocity dispersion σ, and the ionized gas velocity (Hβ and/or [O III]) are presented for the galaxies in the sample. The stellar rotation curves and velocity dispersion profiles are determined for 13 galaxies, and the ionized gas rotation curves are determined for 6 galaxies. Misalignments between the optical and kinematical major axes are found in several galaxies. While in some cases this is due to a bar, in other cases it seems to be associated with gravitational interaction or ongoing ram pressure stripping. Non-circular gas motions are found in nine galaxies, with various causes including bars, nuclear outflows, or gravitational disturbances. Several galaxies have signatures of kinematically distinct stellar components, which are likely signatures of accretion or mergers. For all of our galaxies, we compute the angular momentum parameter λ {sub R}. An evaluation of the galaxies in the λ {sub R} ellipticity plane shows that all but two of the galaxies have significant support from random stellar motions, and have likely experienced gravitational interactions. This includes some galaxies with very small bulges and truncated/compact Hα morphologies, indicating that such galaxies cannot be fully explained by simple ram pressure stripping, but must have had significant gravitational encounters. Most of the sample galaxies show evidence for ICM-ISM stripping as well as gravitational interactions, indicating that the evolution of a significant fraction of cluster galaxies is likely strongly impacted by both effects.

  8. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system

    PubMed Central

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection. PMID:26218927

  9. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system.

    PubMed

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection.

  10. Spatially resolved integral field spectroscopy of the ionized gas in IZw18

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Vílchez, J. M.; Pérez-Montero, E.; Iglesias-Páramo, J.; Hernández-Fernández, J. D.; Duarte Puertas, S.; Brinchmann, J.; Durret, F.; Kunth, D.

    2016-07-01

    We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding the properties most closely resembling those prevailing at distant starbursts. Our IFU aperture (˜1.4 × 1.4 kpc2) samples the entire IZw18 main body and an extended region of its ionized gas. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located close to the north-west knot and thereabouts. We detect a Wolf-Rayet feature near the north-west knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity indicator R23 and the ionization parameter (as traced by [O III]/[O II]) across IZw18. Over ˜0.30 kpc2, using the [O III] λ4363 line, we compute Te[O III] values (˜15 000-25 000 K), and oxygen abundances are derived from the direct determinations of Te[O III]. More than 70 per cent of the higher-Te[O III] (≳22 000 K) spaxels are He IIλ4686-emitting spaxels too. From a statistical analysis, we study the presence of variations in the ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the error-weighted mean of 12 + log(O/H) = 7.11 ± 0.01 is taken as the representative O/H for IZw18. Aperture effects on the derivation of O/H are discussed. Using our IFU data we obtain, for the first time, the IZw18 integrated spectrum.

  11. GAS ACCRETION IS DOMINATED BY WARM IONIZED GAS IN MILKY WAY MASS GALAXIES AT z {approx} 0

    SciTech Connect

    Joung, M. Ryan; Putman, Mary E.; Bryan, Greg L.; Fernandez, Ximena; Peek, J. E. G.

    2012-11-10

    We perform high-resolution hydrodynamic simulations of a Milky Way mass galaxy in a fully cosmological setting using the adaptive mesh refinement code, Enzo, and study the kinematics of gas in the simulated galactic halo. We find that the gas inflow occurs mostly along filamentary structures in the halo. The warm-hot (10{sup 5} K 10{sup 6} K) ionized gases are found to dominate the overall mass accretion in the system (with M-dot = 3-5 M {sub Sun} yr{sup -1}) over a large range of distances, extending from the virial radius to the vicinity of the disk. Most of the inflowing gas (by mass) does not cool, and the small fraction that manages to cool does so primarily close to the galaxy (R {approx}< 100 kpc, with more pronounced cooling at smaller R), perhaps comprising the neutral gas that may be detectable as, e.g., high-velocity clouds. The neutral clouds are embedded within larger, accreting filamentary flows, and represent only a small fraction of the total mass inflow rate. The inflowing gas has relatively low metallicity (Z/Z {sub Sun} < 0.2). The outer layers of the filamentary inflows are heated due to compression as they approach the disk. In addition to the inflow, we find high-velocity, metal-enriched outflows of hot gas driven by supernova feedback. Our results are consistent with observations of halo gas at low z.

  12. Baryonic distributions in galaxy dark matter haloes - I. New observations of neutral and ionized gas kinematics

    NASA Astrophysics Data System (ADS)

    Richards, Emily E.; van Zee, L.; Barnes, K. L.; Staudaher, S.; Dale, D. A.; Braun, T. T.; Wavle, D. C.; Dalcanton, J. J.; Bullock, J. S.; Chandar, R.

    2016-07-01

    We present a combination of new and archival neutral hydrogen (H I) observations and new ionized gas spectroscopic observations for 16 galaxies in the statistically representative Extended Disk Galaxy Explore Science kinematic sample. H I rotation curves are derived from new and archival radio synthesis observations from the Very Large Array (VLA) as well as processed data products from the Westerbork Radio Synthesis Telescope (WSRT). The H I rotation curves are supplemented with optical spectroscopic integral field unit (IFU) observations using SparsePak on the WIYN 3.5 m telescope to constrain the central ionized gas kinematics in 12 galaxies. The full rotation curves of each galaxy are decomposed into baryonic and dark matter halo components using 3.6μm images from the Spitzer Space Telescope for the stellar content, the neutral hydrogen data for the atomic gas component, and, when available, CO data from the literature for the molecular gas component. Differences in the inferred distribution of mass are illustrated under fixed stellar mass-to-light ratio (M/L) and maximum disc/bulge assumptions in the rotation curve decomposition.

  13. Ionized gas pressure correlates with star formation intensity in nearby starbursts

    NASA Astrophysics Data System (ADS)

    Jiang, Tianxing; Malhotra, Sangeeta; Yang, Huan

    2016-06-01

    We estimate the electron density of the ionized gas and thus the thermal pressure in HII regions; and compare that to the SFR (star formation rate) surface density for a combined sample of about 40 green peas and Lyman Break Analogs at z < 0.30. The electron density of the ionized gas is measured from sulfur line ratio ([SII] 6716 / 6731). We find that the SFR surface density is correlated with the electron density and the thermal pressure in HII regions for the star-forming galaxies with SFR surface density above a certain threshold. This work shows quantitatively the correlation between SFR surface density and electron density and that between SFR surface density and the thermal pressure in HII regions for the nearby starburst galaxies. This is consistent with theoretical models of disks (e.g. Kim et al. (2011) if we assume that the thermal pressure in HII regions is comparable to the total diffuse gas pressure at the midplane of the diffuse neutral gas. It is also in agreement with the results from star-forming galaxies at z ~ 2.5. We might infer that the starburst galaxies at low-redshift (z < 0.3) share similar physical properties to the galaxies at high redshift (z ~ 2.5).

  14. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    NASA Astrophysics Data System (ADS)

    Makito, K.; Zhidkov, A.; Hosokai, T.; Shin, J.-H.; Masuda, S.; Kodama, R.

    2012-10-01

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of ˜3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  15. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    SciTech Connect

    Makito, K.; Shin, J.-H.; Zhidkov, A.; Hosokai, T.; Masuda, S.; Kodama, R.

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  16. Ionized gas velocity dispersion in nearby dwarf galaxies: looking at supersonic turbulent motions

    NASA Astrophysics Data System (ADS)

    Moiseev, Alexei V.; Lozinskaya, Tatiana A.

    2012-06-01

    We present the results of an ionized gas turbulent motions study in several nearby dwarf galaxies using a scanning Fabry-Perot interferometer with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). Combining the ‘intensity-velocity dispersion’ diagrams (?) with two-dimensional maps of radial velocity dispersion, we found a number of common patterns pointing to the relation between the value of chaotic ionized gas motions and processes of current star formation. In five out of the seven analysed galaxies, we identified expanding shells of ionized gas with diameters of 80-350 pc and kinematic ages of 1-4 Myr. We also demonstrate that the ? diagrams may be useful for the search of supernova remnants, other small expanding shells or unique stars in nearby galaxies. As an example, a candidate luminous blue variable (LBV) was found in UGC 8508. We propose some additions to the interpretation, previously used by Muñoz-Tuñón et al. to explain the ? diagrams for giant star formation regions. In the case of dwarf galaxies, a major part of the regions with high velocity dispersion belongs to the diffuse low surface brightness emission, surrounding the star-forming regions. We attribute this to the presence of perturbed low-density gas with high values of turbulent velocities around the giant H II regions. Based on observations obtained with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The observations were carried out with the financial support of the Ministry of Education and Science of Russian Federation (contracts no. 16.518.11.7073 and 16.552.11.7028).

  17. Observations of feedback from radio-quiet quasars - I. Extents and morphologies of ionized gas nebulae

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.; Nesvadba, Nicole P. H.; Liu, Xin

    2013-04-01

    Black hole feedback - the strong interaction between the energy output of supermassive black holes and their surrounding environments - is routinely invoked to explain the absence of overly luminous galaxies, the black hole versus bulge correlations and the similarity of black hole accretion and star formation histories. Yet direct probes of this process in action are scarce and limited to small samples of active nuclei. In this paper, we present Gemini Integral Field Unit observations of the distribution of ionized gas around luminous, obscured, radio-quiet quasars at z ˜ 0.5. We detect extended ionized gas nebulae via [O III] λ5007 Å emission in every case, with a mean diameter of 28 kpc. These nebulae are nearly perfectly round, with Hβ surface brightness declining ∝R-3.5 ± 1.0. The regular morphologies of nebulae around radio-quiet quasars are in striking contrast with lumpy or elongated [O III] nebulae seen around radio galaxies at low and high redshifts. We present the uniformly measured size-luminosity relationship of [O III] nebulae around Seyfert 2 galaxies and type 2 quasars spanning six orders of magnitude in luminosity and confirm the flat slope of the correlation (R_{[O III]}∝ L_{[O III]}^{0.25± 0.02}). We propose a model of clumpy nebulae in which clouds that produce line emission transition from being ionization-bounded at small distances from the quasar to being matter-bounded in the outer parts of the nebula. The model - which has a declining pressure profile - qualitatively explains line ratio profiles and surface brightness profiles seen in our sample. It is striking that we see such smooth and round large-scale gas nebulosities in this sample, which are inconsistent with illuminated merger debris and which we suggest may be the signature of accretion energy from the nucleus reaching gas at large scales.

  18. Gas Chromatography/Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry for Fingerprinting the Macondo Oil Spill.

    PubMed

    Lobodin, Vladislav V; Maksimova, Ekaterina V; Rodgers, Ryan P

    2016-07-01

    We report the first application of a new mass spectrometry technique (gas chromatography combined to atmospheric pressure chemical ionization tandem mass spectrometry, GC/APCI-MS/MS) for fingerprinting a crude oil and environmental samples from the largest accidental marine oil spill in history (the Macondo oil spill, the Gulf of Mexico, 2010). The fingerprinting of the oil spill is based on a trace analysis of petroleum biomarkers (steranes, diasteranes, and pentacyclic triterpanes) naturally occurring in crude oil. GC/APCI enables soft ionization of petroleum compounds that form abundant molecular ions without (or little) fragmentation. The ability to operate the instrument simultaneously in several tandem mass spectrometry (MS/MS) modes (e.g., full scan, product ion scan, reaction monitoring) significantly improves structural information content and sensitivity of analysis. For fingerprinting the oil spill, we constructed diagrams and conducted correlation studies that measure the similarity between environmental samples and enable us to differentiate the Macondo oil spill from other sources.

  19. Electron capture and ionization of 33-TeV Pb ions in gas targets

    SciTech Connect

    Krause, H. F.; Vane, C. R.; Datz, S.; Grafstro''m, P.; Knudsen, H.; Mikkelsen, U.; Scheidenberger, C.; Schuch, R. H.; Vilakazi, Z.

    2001-03-01

    We have measured the total cross sections for electron capture by bare Pb{sup 82+} ions and for the ionization of hydrogenlike Pb{sup 81+}(1s) ions at 158GeV/A, {gamma}=168, in Ar, Kr, and Xe gas targets. At this energy, the total capture cross sections are dominated by electron capture from pair production. The capture measurements are compared with the results of several theoretical calculations and with similar measurements made with solid targets. The Pb{sup 81+}(1s) ionization cross sections obtained, which are substantially lower than those measured in solids, agree well with recent calculations that predict saturation at high energies from target screening effects.

  20. Imaging spectrophotometry of ionized gas in NGC 1068. I - Kinematics of the narrow-line region

    NASA Technical Reports Server (NTRS)

    Cecil, Gerald; Bland, Jonathan; Tully, R. Brent

    1990-01-01

    The kinematics of collisionally excited forbidden N II 6548, 6583 across the inner 1 arcmin diameter of the nearby Seyfert galaxy NGC 1068 is mapped using an imaging Fabry-Perot interferometer and low-noise CCD. The stack of monochromatic images, which spatially resolved the high-velocity gas, was analyzed for kinematic and photometric content. Profiles agree well with previous long-slit work, and their complete spatial coverage makes it possible to constrain the gas volume distribution. It is found that the narrow-line region is distributed in a thick center-darkened, line-emitting cylinder that envelopes the collimated radio jet. Three distinct kinematic subsystems, of which the cylinder is composed, are discussed in detail. Detailed behavior of the emission-line profiles, at the few points in the NE quadrant with simple kinematics, argues that the ionized gas develops a significant component of motion perpendicular to the jet axis.

  1. WARM IONIZED GAS REVEALED IN THE MAGELLANIC BRIDGE TIDAL REMNANT: CONSTRAINING THE BARYON CONTENT AND THE ESCAPING IONIZING PHOTONS AROUND DWARF GALAXIES

    SciTech Connect

    Barger, K. A.; Haffner, L. M.; Bland-Hawthorn, J. E-mail: haffner@astro.wisc.edu

    2013-07-10

    The Magellanic System includes some of the nearest examples of galaxies disturbed by galaxy interactions. These interactions have redistributed much of their gas into the halos of the Milky Way (MW) and the Magellanic Clouds. We present Wisconsin H{alpha} Mapper kinematically resolved observations of the warm ionized gas in the Magellanic Bridge over the velocity range of +100 to +300 km s{sup -1} in the local standard of rest reference frame. These observations include the first full H{alpha} intensity map and the corresponding intensity-weighted mean velocity map of the Magellanic Bridge across (l, b) = (281 Degree-Sign .5, -30 Degree-Sign .0) to (302. Degree-Sign 5, -46. Degree-Sign 7). Using the H{alpha} emission from the Small Magellanic Cloud (SMC)-Tail and the Bridge, we estimate that the mass of the ionized material is between (0.7-1.7) Multiplication-Sign 10{sup 8} M{sub Sun }, compared to 3.3 Multiplication-Sign 10{sup 8} M{sub Sun} for the neutral mass over the same region. The diffuse Bridge is significantly more ionized than the SMC-Tail, with an ionization fraction of 36%-52% compared to 5%-24% for the Tail. The H{alpha} emission has a complex multiple-component structure with a velocity distribution that could trace the sources of ionization or distinct ionized structures. We find that incident radiation from the extragalactic background and the MW alone are insufficient to produced the observed ionization in the Magellanic Bridge and present a model for the escape fraction of the ionizing photons from both the SMC and Large Magellanic Cloud (LMC). With this model, we place an upper limit of 4.0% for the average escape fraction of ionizing photons from the LMC and an upper limit of 5.5% for the SMC. These results, combined with the findings of a half a dozen other studies for dwarf galaxies in different environments, provide compelling evidence that only a small percentage of the ionizing photons escape from dwarf galaxies in the present epoch to

  2. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column.

    PubMed

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  3. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  4. Ionized gas outflow in the isolated S0 galaxy NGC 4460

    NASA Astrophysics Data System (ADS)

    Moiseev, Alexei; Karachentsev, Igor; Kaisin, Serafim

    2010-04-01

    We used integral-field and long-slit spectroscopy to study a bright extended nebulosity recently discovered in the isolated lenticular galaxy NGC 4460 during an Hα survey of nearby galaxies. An analysis of archival Sloan Digital Sky Survey, GALEX and Hubble Space Telescope images indicates that current star formation is entirely concentrated in the central kiloparsec of the galaxy disc. The observed ionized gas parameters (morphology, kinematics and ionization state) can be explained by a gas outflow above the plane of the galaxy, caused by star formation in the circumnuclear region. Galactic wind parameters in NGC 4460 (outflow velocity, total kinetic energy) are several times smaller, compared with the known galactic wind in NGC 253, which is explained by the substantially lower total star formation rate. We discuss the cause of the star formation processes in NGC 4460 and in two other known isolated lenticular (S0) and elliptical (E) galaxies of the Local Volume: NGC 404 and 855. We provide evidence suggesting that the feeding of isolated galaxies by intergalactic gas on a cosmological time-scale is a steady process without significant variations. Based on observations collected with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, which is operated under the financial support of the Science Department of Russia (registration number 01-43). E-mail: moisav@gmail.com

  5. Ionized gas in the circumgalactic vicinity of the M81 galaxy group

    NASA Astrophysics Data System (ADS)

    Al Najm, M. N.; Polikarpova, O. L.; Shchekinov, Yu. A.

    2016-04-01

    The dynamics of the dust and gas in the tidal region of the M81 galaxy group have been analyzed, and the drift of the dust relative to the gas has been estimated, including the drift due to the action of radiation pressure from stars in M81. It is concluded that a large fraction of the gas in the tidal region is in the form of ionized hydrogen HII that shields the observedHI gas from the extragalactic Lyman continuum: the observed atomic gas could be only 10% of the total mass of gas. Only then it is possible to satisfactorily explain the excess dust abundance, which exceeds the Galactic value by a factor of six. By analogy, extended HI disks in galaxies with sizes appreciably larger than the stellar disks could be surrounded by HII envelopes with a comparable or greater mass. Such disks could play an important role in supporting prolonged star formation in galaxies with extended HI disks. Associated observational manifestations are discussed. Such HII envelopes outside HI disks could be detectable in absorption in Ly α and lines of ions of heavy elements.

  6. NEBULAR: Spectrum synthesis for mixed hydrogen-helium gas in ionization equilibrium

    NASA Astrophysics Data System (ADS)

    Schirmer, Mischa

    2016-08-01

    NEBULAR synthesizes the spectrum of a mixed hydrogen helium gas in collisional ionization equilibrium. It is not a spectral fitting code, but it can be used to resample a model spectrum onto the wavelength grid of a real observation. It supports a wide range of temperatures and densities. NEBULAR includes free-free, free-bound, two-photon and line emission from HI, HeI and HeII. The code will either return the composite model spectrum, or, if desired, the unrescaled atomic emission coefficients. It is written in C++ and depends on the GNU Scientific Library (GSL).

  7. 3D Spectroscopy of the Ionized Gas Kinematics in Galactic Rings

    NASA Astrophysics Data System (ADS)

    Moiseev, A. V.

    2008-10-01

    The kinematics of galactic rings were studied with a scanning Fabry-Perot interferometer mounted in the multi-mode focal reducer SCORPIO tep{moiseev:afan} at the SAO RAS 6-m telescope. The analysis of the ionized-gas velocity fields allows us to understand the nature of the ring formation in several galaxies. The different (resonance, collisional, and polar) types of rings in the studied objects were caused by the various sorts of interactions (e.g., merging and head-on collisions)

  8. The PG X-ray QSO Sample: Ionizing Continuum and Properties of the Fueling Gas

    NASA Astrophysics Data System (ADS)

    Wills, B. J.; Laor, A.; Brotherton, M. S.; Wills, D.; Shang, Zhaohui; Wilkes, B. J.; Ferland, G. J.

    1998-12-01

    The UV to soft X-rays of luminous AGNs dominate their bolometric luminosity, driven by an accretion-powered dynamo at the center. These photons illuminate the surrounding gas, providing clues to fueling and exhaust. Two sets of important relationships -- neither of them understood -- link the continuum and gas properties. These are the Baldwin relations between equivalent width and luminosity, and the so-called `Eigenvector 1' relationships linking steeper X-ray spectra with narrower BLR Hβ and stronger Fe II (optical), and weaker NLR [O III]lambda 5007 emission (Boroson & Green 1992, Laor et al. 1994, 1997). These relationships plausibly link the central engine with structure, dynamics and physical conditions in sub-parsec to Kiloparsec scale gas. In order to investigate these relationships further we study the links between optical and ultraviolet emission lines, and the UV and soft-X-ray ionizing continuum. We have obtained HST UV and McDonald ground-based spectra for a unique sample -- a complete sample of PG QSOs chosen for low redshift and low Galactic reddening by Laor et al. (1994) in order to obtain high-quality information on the ionizing continuum. We show that the above eigenvector 1 relationships extend to many properties of the UV spectrum. We present examples of the new set of correlations, and speculate that a starburst origin for a component of QSO gas might explain its geometry, abundances and density. The link with dynamics and UV--X-ray SED suggests that this gas is fueling the accretion-driven central engine.

  9. Jet-driven outflows of ionized gas in the nearby radio galaxy 3C 293

    NASA Astrophysics Data System (ADS)

    Mahony, E. K.; Oonk, J. B. R.; Morganti, R.; Tadhunter, C.; Bessiere, P.; Short, P.; Emonts, B. H. C.; Oosterloo, T. A.

    2016-01-01

    Fast outflows of gas, driven by the interaction between the radio jets and interstellar medium (ISM) of the host galaxy, are being observed in an increasing number of galaxies. One such example is the nearby radio galaxy 3C 293. In this paper we present integral field unit observations taken with OASIS on the William Herschel Telescope, enabling us to map the spatial extent of the ionized gas outflows across the central regions of the galaxy. The jet-driven outflow in 3C 293 is detected along the inner radio lobes with a mass outflow rate ranging from ˜0.05 to 0.17 M⊙ yr-1 (in ionized gas) and corresponding kinetic power of ˜0.5-3.5 × 1040 erg s-1. Investigating the kinematics of the gas surrounding the radio jets (i.e. not directly associated with the outflow), we find linewidths broader than 300 km s-1 up to 5 kpc in the radial direction from the nucleus (corresponding to 3.5 kpc in the direction perpendicular to the radio axis at maximum extent). Along the axis of the radio jet linewidths >400 km s-1 are detected out to 7 kpc from the nucleus and linewidths of >500 km s-1 at a distance of 12 kpc from the nucleus, indicating that the disturbed kinematics clearly extend well beyond the high surface brightness radio structures of the jets. This is suggestive of the cocoon structure seen in simulations of jet-ISM interaction and implies that the radio jets are capable of disturbing the gas throughout the central regions of the host galaxy in all directions.

  10. Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Arribas, S.; Colina, L.; Bellocchi, E.; Maiolino, R.; Villar-Martín, M.

    2014-08-01

    We study the kinematic properties of the ionised gas outflows and ambient interstellar medium (ISM) in a large and representative sample of local luminous and ultra-luminous infrared galaxies (U/LIRGs) (58 systems, 75 galaxies) at galactic and sub-galactic (i.e., star-forming clumps) scales, thanks to integral field spectroscopy (IFS)-based high signal-to-noise integrated spectra. The velocity dispersion of the ionized ISM in U/LIRGs (⟨ σ ⟩ ~ 70 km s-1) is larger than in lower luminosity local star-forming galaxies (⟨ σ ⟩ ~ 25 km s-1). While for isolated disc LIRGs star formation appears to sustain turbulence, gravitational energy release associated with interactions and mergers plays an important role in driving σ in the U/LIRG range. We find that σ has a dependency on the star formation rate density (ΣSFR), which is weaker than expected if it were driven by the energy released by the starburst. The relatively small role of star formation (SF) driving the σ in U/LIRGs is reinforced by the lack of an increase in σ associated with high luminosity SF clumps. We also find that the impact of an active galactic nucleus (AGN) in ULIRGs is strong, increasing on average σ by a factor 1.5. Low-z U/LIRGs cover a range of velocity dispersion (σ ~ 30 to 100 km s-1) and star formation rate density (ΣSFR ~ 0.1 to 20 M⊙ yr-1 kpc-2) similar to those of high-z SFGs. Moreover, the observed weak dependency of σ on ΣSFR for local U/LIRGs (σ ∝ ΣSFR+0.06) is in very good agreement with that measured in some high-z samples. The presence of ionized gas outflows in U/LIRGs seems universal based on the detection of a broad, usually blueshifted, Hα line. The observed dependency of the maximum velocity of the outflow (Vmax) on the star formation rate (SFR) is of the type Vmax(non - AGN) ∝ SFR(LIR)+ 0.24. We find that AGNs in U/LIRGs are able to generate faster (~×2) and more massive (~× 1.4) ionized gas outflows than pure starbursts. The derived ionized mass

  11. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION

    EPA Science Inventory

    The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

  12. 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.

  13. Ionized gas kinematics within the inner kiloparsec of the Seyfert galaxy NGC 1365

    NASA Astrophysics Data System (ADS)

    Lena, Davide; Robinson, Andrew; Storchi-Bergmann, Thaisa; Couto, Guilherme S.; Schnorr-Müller, Allan; Riffel, Rogemar A.

    2016-07-01

    We observed the nuclear region of the galaxy NGC 1365 with the integral field unit of the Gemini Multi Object Spectrograph mounted on the GEMINI-South telescope. The field of view covers 13 × 6 arcsec2(1173 × 541 pc2) centred on the nucleus, at a spatial resolution of 52 pc. The spectral coverage extends from 5600 to 7000 Å, at a spectral resolution R = 1918. NGC 1365 hosts a Seyfert 1.8 nucleus, and exhibits a prominent bar extending out to 100 arcsec (9 kpc) from the nucleus. The field of view lies within the inner Lindblad resonance. Within this region, we found that the kinematics of the ionized gas (as traced by [O I], [N II], Hα, and [S II]) is consistent with rotation in the large-scale plane of the galaxy. While rotation dominates the kinematics, there is also evidence for a fan-shaped outflow, as found in other studies based on the [O III] emission lines. Although evidence for gas inflowing along nuclear spirals has been found in a few barred galaxies, we find no obvious signs of such features in the inner kiloparsec of NGC 1365. However, the emission lines exhibit a puzzling asymmetry that could originate from gas which is slower than the gas responsible for the bulk of the narrow-line emission. We speculate that it could be tracing gas which lost angular momentum, and is slowly migrating from the inner Lindblad resonance towards the nucleus of the galaxy.

  14. Isothermal flow measurements in a gas turbine combustor using a fast flame ionization detector

    NASA Astrophysics Data System (ADS)

    Read, R. W.; Hochgreb, S.

    2010-05-01

    A fast-response flame ionization detector (FFID) has been used to study isothermal gas transport and mixing inside a gas turbine combustion chamber. The large, highly linear dynamic range of the FFID coupled with a frequency response that extends up to approximately 200 Hz can reveal large-scale features of interest in turbulent flows. Experiments were performed in a ground-based test facility simulating high-altitude restart conditions. Pulses of propane were discharged into the core swirler of a fuel injector through a high-speed valve. The mole fraction of this tracer was monitored at various locations inside the combustion chamber. These measurements allowed the identification of recirculation timescales and flow instabilities at different points inside the combustion chamber, providing important insights into the altitude restart process.

  15. Dynamic self-organization phenomena in complex ionized gas systems: new paradigms and technological aspects

    NASA Astrophysics Data System (ADS)

    Vladimirov, S. V.; Ostrikov, K.

    2004-04-01

    An overview of dynamic self-organization phenomena in complex ionized gas systems, associated physical phenomena, and industrial applications is presented. The most recent experimental, theoretical, and modeling efforts to understand the growth mechanisms and dynamics of nano- and micron-sized particles, as well as the unique properties of the plasma-particle systems (colloidal, or complex plasmas) and the associated physical phenomena are reviewed and the major technological applications of micro- and nanoparticles are discussed. Until recently, such particles were considered mostly as a potential hazard for the microelectronic manufacturing and significant efforts were applied to remove them from the processing volume or suppress the gas-phase coagulation. Nowadays, fine clusters and particulates find numerous challenging applications in fundamental science as well as in nanotechnology and other leading high-tech industries.

  16. High-field plasma acceleration in a high-ionization-potential gas

    NASA Astrophysics Data System (ADS)

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-06-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources.

  17. High-field plasma acceleration in a high-ionization-potential gas

    DOE PAGES

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; et al

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. In our research, we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by upmore » to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. Lastly, the results open new possibilities for the design of particle beam drivers and plasma sources.« less

  18. High-field plasma acceleration in a high-ionization-potential gas

    PubMed Central

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-01-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m−1, over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720

  19. High-field plasma acceleration in a high-ionization-potential gas.

    PubMed

    Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clausse, B; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Litos, M; Lu, W; Marsh, K A; Mori, W B; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V

    2016-01-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m(-1), over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720

  20. Gas kinematics and ionization along the extended sight line to HD 116852

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Savage, Blair D.

    1994-01-01

    We present Goddard High-Resolution Spectrograph intermediate observations of the interstellar medium toward HD 116852, a low halo star at a distance of 4.8 kpc (z = -1.3 kpc) in the direction l = 304. deg 9, b = 16.deg 1. The small science aperture observations have signal-to-noise ratios ranging from 30 to 90 and resolutions of 11 to 18 km/s (FWHM). We confirm the optical MK classification of this star through an analysis of its ultraviolet photosperic and stellar wind profiles. We detect interstellar lines of Al III, Si IV, C IV, and N V together with lines of C I, C I*, C I**, Si II, Ge II, P II, and Ni II. We convert the Mg II, P II, S II, Al III, Si IV, C IV, and N V profiles into measure of apparent column density as a function of LSR velocity. Gas scale height, velocity dispersion, and differential Galactic rotation effects govern the profile shapes. A simple computer model of the expected sight line column density profiles for the low and high ion species indicates that the gas velocity dispersions and scale heights increase as the ionization level of the gas increases. We find scale heigts H greater than or = 1 kpc for the high ions, which are comparable to the z-distance of the star, whereas we find H approximatley = 0.6 to 0.7 kpc for A1 III and H approximatley 0.1 kpc for P II and Ge II. An enhancement in the Al II profile near -15 km/s accounts for approximately 25% of the A1 III column along the sight line and probably arises within gas located approximately 500 pc below the Sagittarius-Carina spiral arm link. Portions of the broad underlying A1 III distribution are associated with the higher ionization lines, perhaps in conductive interfaces. The presence of N V and the column density ratios of Si IV, C IV, and N V favor the interpretation that much of the high ion absorption is produced by collisional ionization in gas with T = 1-3 x 10(exp 5) K. An enhancement near -35 km/s in both the Si IV and C IV profiles may be due to an outflow from the Norma

  1. Dust and ionized gas in elliptical galaxies: Signatures of merging collisions

    NASA Technical Reports Server (NTRS)

    Goudfrooij, Paul; Dejong, Teije

    1993-01-01

    Traditionally elliptical galaxies were thought to be essentially devoid of interstellar matter. However, recent advances in instrumental sensitivity have caused a renaissance of interest in dust and gas in - or associated with - elliptical galaxies. In particular, the technique of co-adding IRAS survey scans has led to the detection of more than half of all ellipticals with BT less than 11 mag. in the Revised Shapley-Ames catalog, indicating the presence of 10(exp 7) - 10(exp 8) solar mass of cold interstellar matter (Jura et al. 1987). In addition, CCD multi-color surface photometry shows dust patches in about 30 percent of the cases studied to date (e.g., Veron-Cetty & Veron 1988). Thorough study of the gas and dust in ellipticals is important to (1) determine its origin (mass-loss from late-type stars, merging collisions with other galaxies or accretion inflows from cooling X-ray gas), and (2) investigate the 3-D shape of ellipticals, as can be derived from the orientation of the dust lanes and the 2-D velocity field of the gas. An important result of our comprehensive CCD imaging program is that a relevant fraction (approximately 40 percent) of the sample objects exhibits dust patches within extended H-alpha+(NII) line-emitting filaments. This common occurrence can be easily accounted for if the dust and gas have an external origin, i.e., mergers or interactions with gas-rich galaxies. Evidence supporting this suggestion: (1) the ionized gas is usually dynamically decoupled from the stellar velocity field (see, e.g., Sharples et al. 1983, Bertola & Bettoni 1988); (2) it is shown in a companion paper (Goudfrooij et al. 1992) that internal stellar mass loss alone can not account for the dust content of elliptical galaxies.

  2. Highly ionized interstellar gas located in the Galactic disk and halo

    SciTech Connect

    Savage, B.D.; Massa, D.

    1987-03-01

    High-resolution IUE absorption line spectra have been obtained for 40 distant stars in order to study the distribution of interstellar H I, Si IV, C IV, and N V in the Galactic disk and lower halo. Respective midplane densities of 2 x 10 to the -9th, 7 x 10 to the -9th, and 3 x 10 to the -9th are found for Si IV, C IV, and Ni V. Both column density and velocity data indicate that the highly ionized gas (HIG) is considerably more extended in directions away from the Galactic plane than is H I or Si II. The absorption-line velocities for the halo HIG are consistent with the notion that halo gas in the inner Galaxy rotates more slowly than gas in the underlying disk. The derived column densities suggest an exponential scale height for the HIG of about 3 kpc; however, a simple exponential distribution is a poor representation of the distribution of the gas. It is concluded that a full explanation of the origin of the halo HIG will probably require a blending of ideas from the Galactic fountain and the photoionized halo models. 75 references.

  3. Observations of feedback from radio-quiet quasars - II. Kinematics of ionized gas nebulae

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.; Nesvadba, Nicole P. H.; Liu, Xin

    2013-12-01

    The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around 11 luminous, obscured, radio-quiet quasars at z ˜ 0.5 out to ˜15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III] λ5007 Å emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80 per cent of the emission as high as 103 km s-1) combined with relatively small velocity difference across them (from 90 to 520 km s-1) point towards wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km s-1, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly towards outer parts of the nebulae (by 3 per cent kpc-1 on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find dot{E}_kin between 4 × 1044 and 3 × 1045 erg s-1 and dot{M} between 2 × 103 and 2 × 104 M⊙ yr-1. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ˜2 per cent. We report four new candidates for `superbubbles' - outflows that may have broken out of the denser regions of the host galaxy.

  4. Spectacular tails of ionized gas in the Virgo cluster galaxy NGC 4569

    NASA Astrophysics Data System (ADS)

    Boselli, A.; Cuillandre, J. C.; Fossati, M.; Boissier, S.; Bomans, D.; Consolandi, G.; Anselmi, G.; Cortese, L.; Côté, P.; Durrell, P.; Ferrarese, L.; Fumagalli, M.; Gavazzi, G.; Gwyn, S.; Hensler, G.; Sun, M.; Toloba, E.

    2016-03-01

    Context. Using MegaCam at the CFHT, we obtained a deep narrow band Hα+[NII] wide-field image of NGC 4569 (M90), the brightest late-type galaxy in the Virgo cluster. The image reveals the presence of long tails of diffuse ionized gas, without any associated stellar component extending from the disc of the galaxy up to ≃80 kpc (projected distance) and with a typical surface brightness of a few 10-18 erg s-1 cm-2 arcsec-2. These features provide direct evidence that NGC 4569 is undergoing a ram-presure stripping event. The image also shows a prominent 8 kpc spur of ionized gas that is associated with the nucleus that spectroscopic data identify as an outflow. With some assumptions on the 3D distribution of the gas, we use the Hα surface brightness of these extended low-surface brightness features to derive the density and the mass of the gas that has been stripped during the interaction of the galaxy with the intracluster medium. The comparison with ad hoc chemo-spectrophotometric models of galaxy evolution indicates that the mass of the Hα emitting gas in the tail is a large fraction of that of the cold phase that has been stripped from the disc, suggesting that the gas is ionized within the tail during the stripping process. The lack of star-forming regions suggests that mechanisms other than photoionization are responsible for the excitation of the gas (shocks, heat conduction, magneto hydrodynamic waves). This analysis indicates that ram pressure stripping is efficient in massive (Mstar ≃ 1010.5 M⊙) galaxies located in intermediate-mass (≃1014 M⊙) clusters under formation. It also shows that the mass of gas expelled by the nuclear outflow is only ~1% than that removed during the ram pressure stripping event.Together these results indicate that ram pressure stripping, rather than starvation through nuclear feedback, can be the dominant mechanism that is responsible for the quenching of the star formation activity of galaxies in high density

  5. Ionization heating in rare-gas clusters under intense XUV laser pulses

    SciTech Connect

    Arbeiter, Mathias; Fennel, Thomas

    2010-07-15

    The interaction of intense extreme ultraviolet (XUV) laser pulses ({lambda}=32 nm, I=10{sup 11}-10{sup 14} W/cm{sup 2}) with small rare-gas clusters (Ar{sub 147}) is studied by quasiclassical molecular dynamics simulations. Our analysis supports a very general picture of the charging and heating dynamics in finite samples under short-wavelength radiation that is of relevance for several applications of free-electron lasers. First, up to a certain photon flux, ionization proceeds as a series of direct photoemission events producing a jellium-like cluster potential and a characteristic plateau in the photoelectron spectrum as observed in Bostedt et al. [Phys. Rev. Lett. 100, 133401 (2008)]. Second, beyond the onset of photoelectron trapping, nanoplasma formation leads to evaporative electron emission with a characteristic thermal tail in the electron spectrum. A detailed analysis of this transition is presented. Third, in contrast to the behavior in the infrared or low vacuum ultraviolet range, the nanoplasma energy capture proceeds via ionization heating, i.e., inner photoionization of localized electrons, whereas collisional heating of conduction electrons is negligible up to high laser intensities. A direct consequence of the latter is a surprising evolution of the mean energy of emitted electrons as function of laser intensity.

  6. Measurement of photon flux with a miniature gas ionization chamber in a Material Testing Reactor

    NASA Astrophysics Data System (ADS)

    Fourmentel, D.; Filliatre, P.; Villard, J. F.; Lyoussi, A.; Reynard-Carette, C.; Carcreff, H.

    2013-10-01

    Nuclear heating measurements in Material Testing Reactors (MTR) are crucial for the design of the experimental devices and the prediction of the temperature of the hosted samples. Nuclear heating in MTR materials (except fuel) is mainly due to the energy deposition by the photon flux. Therefore, the photon flux is a key input parameter for the computer codes which simulate nuclear heating and temperature reached by samples/devices under irradiation. In the Jules Horowitz MTR under construction at the CEA Cadarache, the maximal expected nuclear heating levels will be about 15 to 18 W g-1 and it will be necessary to assess this parameter with the best accuracy. An experiment was performed at the OSIRIS reactor to combine neutron flux, photon flux and nuclear heating measurements to improve the knowledge of the nuclear heating in MTR. There are few appropriate sensors for selective measurement of the photon flux in MTR even if studies and developments are ongoing. An experiment, called CARMEN-1, was conducted at the OSIRIS MTR and we used in particular a gas ionization chamber based on miniature fission chamber design to measure the photon flux. In this paper, we detail Monte-Carlo simulations to analyze the photon fluxes with ionization chamber measurements and we compare the photon flux calculations to the nuclear heating measurements. These results show a good accordance between photon flux measurements and nuclear heating measurement and allow improving the knowledge of these parameters.

  7. Gas Chromatography/Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry for Fingerprinting the Macondo Oil Spill.

    PubMed

    Lobodin, Vladislav V; Maksimova, Ekaterina V; Rodgers, Ryan P

    2016-07-01

    We report the first application of a new mass spectrometry technique (gas chromatography combined to atmospheric pressure chemical ionization tandem mass spectrometry, GC/APCI-MS/MS) for fingerprinting a crude oil and environmental samples from the largest accidental marine oil spill in history (the Macondo oil spill, the Gulf of Mexico, 2010). The fingerprinting of the oil spill is based on a trace analysis of petroleum biomarkers (steranes, diasteranes, and pentacyclic triterpanes) naturally occurring in crude oil. GC/APCI enables soft ionization of petroleum compounds that form abundant molecular ions without (or little) fragmentation. The ability to operate the instrument simultaneously in several tandem mass spectrometry (MS/MS) modes (e.g., full scan, product ion scan, reaction monitoring) significantly improves structural information content and sensitivity of analysis. For fingerprinting the oil spill, we constructed diagrams and conducted correlation studies that measure the similarity between environmental samples and enable us to differentiate the Macondo oil spill from other sources. PMID:27281271

  8. Identifying Extraplanar Diffuse Ionized Gas in a Sample of MaNGA Galaxies

    NASA Astrophysics Data System (ADS)

    Hubbard, Ryan J.; Diamond-Stanic, Aleksandar M.; MaNGA Team

    2016-01-01

    The efficiency with which galaxies convert gas into stars is driven by the continuous cycle of accretion and feedback processes within the circumgalactic medium. Extraplanar diffuse ionized gas (eDIG) can provide insights into the tumultuous processes that govern the evolution of galactic disks because eDIG emission traces both inflowing and outflowing gas. With the help of state-of-the-art, spatially-resolved spectroscopy from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), we developed a computational method to identify eDIG based on the strength of and spatial extent of optical emission lines for a diverse sample of 550 nearby galaxies. This sample includes roughly half of the MaNGA galaxies that will become publicly available in summer 2016 as part of the Thirteenth Data Release of the Sloan Digital Sky Survey. We identified signatures of eDIG in 8% of the galaxies in this sample, and we found that these signatures are particularly common among galaxies with active star formation and inclination angles >45 degrees. Our analysis of the morphology, incidence, and kinematics of eDIG has important implications for current models of accretion and feedback processes that regulate star formation in galaxies. We acknowledge support from the Astrophysics REU program at the University of Wisconsin-Madison, the National Astronomy Consortium, and The Grainger Foundation.

  9. Rapid measurement of phytosterols in fortified food using gas chromatography with flame ionization detection.

    PubMed

    Duong, Samantha; Strobel, Norbert; Buddhadasa, Saman; Stockham, Katherine; Auldist, Martin; Wales, Bill; Orbell, John; Cran, Marlene

    2016-11-15

    A novel method for the measurement of total phytosterols in fortified food was developed and tested using gas chromatography with flame ionization detection. Unlike existing methods, this technique is capable of simultaneously extracting sterols during saponification thus significantly reducing extraction time and cost. The rapid method is suitable for sterol determination in a range of complex fortified foods including milk, cheese, fat spreads, oils and meat. The main enhancements of this new method include accuracy and precision, robustness, cost effectiveness and labour/time efficiencies. To achieve these advantages, quantification and the critical aspects of saponification were investigated and optimised. The final method demonstrated spiked recoveries in multiple matrices at 85-110% with a relative standard deviation of 1.9% and measurement uncertainty value of 10%.

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

    PubMed

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

    2013-10-01

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

  11. The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

    PubMed Central

    Poveda, Juan Carlos; Román, Alejandro San; Guerrero, Alfonso; Álvarez, Ignacio; Cisneros, Carmen

    2008-01-01

    The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ∼1010 W cm−2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CHm+ (m = 2, 4), C2H4+ and C5H4+2 ions. CH5+ and CH6+ were observed which have not been reported before in photodissociation tetracene experiments. PMID:19325732

  12. Ionized gas (plasma) delivery of reactive oxygen species (ROS) into artificial cells

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Ha; Szili, Endre J.; Jenkins, A. Toby A.; Short, Robert D.

    2014-09-01

    This study was designed to enhance our understanding of how reactive oxygen species (ROS), generated ex situ by ionized gas (plasma), can affect the regulation of signalling processes within cells. A model system, comprising of a suspension of phospholipid vesicles (cell mimics) encapsulating a ROS reporter, was developed to study the plasma delivery of ROS into cells. For the first time it was shown that plasma unequivocally delivers ROS into cells over a sustained period and without compromising cell membrane integrity. An important consideration in cell and biological assays is the presence of serum, which significantly reduced the transfer efficiency of ROS into the vesicles. These results are key to understanding how plasma treatments can be tailored for specific medical or biotechnology applications. Further, the phospholipid vesicle ROS reporter system may find use in other studies involving the application of free radicals in biology and medicine.

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

    PubMed

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

    2013-10-01

    Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon®-11), dichlorodifluoromethane (Freon®-12), dichlorofluoromethane (Freon®-21), chlorodifluoromethane (Freon®-22) and 1,2-dichlorotetrafluoroethane (Freon®-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness. PMID:24005155

  14. Determination of dexamethasone in urine by gas chromatography with negative chemical ionization mass spectrometry.

    PubMed

    Huetos Hidalgo, Olga; Jiménez López, Manuel; Ajenjo Carazo, Elisa; San Andrés Larrea, Manuel; Reuvers, Thea B A

    2003-05-01

    Dexamethasone, as some other synthetic corticosteroids, is licensed for therapy in veterinary practice, but its misuse as a growth promotor, often in combination with beta-agonists, is forbidden. In this report an analytical method is described for the detection and confirmation of very low concentrations of dexamethasone in urine. The influence of enzymatic hydrolysis time of samples with glucuronidase was studied. The proposed method consisted of the enzymatic hydrolysis of urine samples, which were then extracted and concentrated using solid-phase cartridges with mixed reversed-phase materials (OASIS). No further clean-up step was found to be necessary. Eluates were derivatized following a previously described method [Analyst 119 (1994) 2557]. Detection, identification and quantification of residues of this compound was carried out by gas chromatography with mass spectrometry in the negative chemical ionization mode. The proposed procedure permits the determination of dexamethasone in urine at levels as low as 0.2 ng ml(-1)

  15. Self-detection of x-ray Fresnel transmissivity using photoelectron-induced gas ionization

    NASA Astrophysics Data System (ADS)

    Stoupin, Stanislav

    2016-01-01

    Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmissivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach could serve as a basis for non-invasive in situ diagnostics of hard x-ray optics, easy access to complementary x-ray transmissivity data in x-ray reflectivity experiments, and might also pave the way to advanced schemes for angle and energy resolving x-ray detectors.

  16. Rapid measurement of phytosterols in fortified food using gas chromatography with flame ionization detection.

    PubMed

    Duong, Samantha; Strobel, Norbert; Buddhadasa, Saman; Stockham, Katherine; Auldist, Martin; Wales, Bill; Orbell, John; Cran, Marlene

    2016-11-15

    A novel method for the measurement of total phytosterols in fortified food was developed and tested using gas chromatography with flame ionization detection. Unlike existing methods, this technique is capable of simultaneously extracting sterols during saponification thus significantly reducing extraction time and cost. The rapid method is suitable for sterol determination in a range of complex fortified foods including milk, cheese, fat spreads, oils and meat. The main enhancements of this new method include accuracy and precision, robustness, cost effectiveness and labour/time efficiencies. To achieve these advantages, quantification and the critical aspects of saponification were investigated and optimised. The final method demonstrated spiked recoveries in multiple matrices at 85-110% with a relative standard deviation of 1.9% and measurement uncertainty value of 10%. PMID:27283669

  17. Dispersion of seed vapor and gas ionization in an MHD second stage combustor and channel

    SciTech Connect

    Chang, S.L.; Lottes, S.A.; Bouillard, J.X.

    1992-01-01

    An approach is introduced for the simulation of a magnetohydrodynamic system consisting of a second stage combustor, a convergent nozzle, and a channel. The simulation uses an Argonne integral combustion flow computer code and another Argonne channel computer code to predict flow, thermal and electric properties in the seed particle laden reacting flow in the system. The combustion code is a general hydrodynamics computer code for two-phase, two-dimensional, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws for gaseous and condensed phases. The channel code is a multigrid three-dimensional computer code for compressible flow subject to magnetic and electric interactions. Results of this study suggests that (1) the processes of seed particle evaporation, seed vapor dispersion, and gas ionization in the reacting flow are critical to the evaluation of the downstream channel performance and (2) particle size, loading, and inlet profile have strong effects on wall deposition and plasma temperature development.

  18. Dispersion of seed vapor and gas ionization in an MHD second stage combustor and channel

    SciTech Connect

    Chang, S.L.; Lottes, S.A.; Bouillard, J.X.

    1992-07-01

    An approach is introduced for the simulation of a magnetohydrodynamic system consisting of a second stage combustor, a convergent nozzle, and a channel. The simulation uses an Argonne integral combustion flow computer code and another Argonne channel computer code to predict flow, thermal and electric properties in the seed particle laden reacting flow in the system. The combustion code is a general hydrodynamics computer code for two-phase, two-dimensional, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws for gaseous and condensed phases. The channel code is a multigrid three-dimensional computer code for compressible flow subject to magnetic and electric interactions. Results of this study suggests that (1) the processes of seed particle evaporation, seed vapor dispersion, and gas ionization in the reacting flow are critical to the evaluation of the downstream channel performance and (2) particle size, loading, and inlet profile have strong effects on wall deposition and plasma temperature development.

  19. Properties of a weakly ionized NO gas sensor based on multi-walled carbon nanotubes

    SciTech Connect

    Zhang, Jingyuan; Zhang, Yong Pan, Zhigang; Yang, Shuang; Shi, Jinghui; Li, Shengtao; Min, Daomin; Wang, Xiaohua; Liu, Dingxin; Yang, Aijun; Li, Xin

    2015-08-31

    Nitric oxide NO is one of the major targets for environmental monitoring, but the existing NO sensors are limited by their low sensitivity and narrow test range. Here, a NO gas sensor employing multiwalled carbon nanotubes (MWCNTs) was fabricated, and its properties in NO–N{sub 2} mixture were investigated from both emission and ionization. The current I{sub e} passing through the nanotubes cathode was found to decrease with increasing NO concentration and increase linearly in different slopes with the extracting voltage U{sub e}. It is shown that the Schottky barrier of the MWCNTs calculated by I{sub e} increased with NO concentration due to the adsorption of NO gas, which restrained the electron emission and consequently weakened the ionization. The positive ion currents I{sub c} passing through the collecting electrode at different voltages of U{sub e} were found to monotonically decrease with increasing NO concentration, which was induced by both of the reduced electron emission and the consumption of the two excited metastable states N{sub 2}(A{sup 3}∑{sub u}{sup +}) and N{sub 2}(a′{sup 1}∑{sub u}{sup −}) by NO. The sensor exhibited high sensitivity at the low temperature of 30 °C. The calculated conductivity was found to be able to take place of I{sub c} for NO detection in a wide voltage range of 80–150 V U{sub e}.

  20. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-03-01

    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  1. KINEMATICS OF IONIZED GAS AT 0.01 AU OF TW Hya

    SciTech Connect

    Goto, M.; Linz, H.; Henning, Th.; Carmona, A.; Stecklum, B.; Meeus, G.; Usuda, T.

    2012-03-20

    We report two-dimensional spectroastrometry of Br{gamma} emission of TW Hya to study the kinematics of the ionized gas in the star-disk interface region. The spectroastrometry with the integral field spectrograph SINFONI at the Very Large Telescope is sensitive to the positional offset of the line emission down to the physical scale of the stellar diameter ({approx}0.01 AU). The centroid of Br{gamma} emission is displaced to the north with respect to the central star at the blue side of the emission line, and to the south at the red side. The major axis of the centroid motion is P.A. = -20 Degree-Sign , which is nearly equal to the major axis of the protoplanetary disk projected on the sky, previously reported by CO submillimeter spectroscopy (P.A. = -27 Degree-Sign ). The line-of-sight motion of the Br{gamma} emission, in which the northern side of the disk is approaching toward us, is also consistent with the direction of the disk rotation known from the CO observation. The agreement implies that the kinematics of Br{gamma} emission is accounted for by the ionized gas in the inner edge of the disk. A simple modeling of the astrometry, however, indicates that the accretion inflow similarly well reproduces the centroid displacements of Br{gamma}, but only if the position angles of the centroid motion and the projected disk ellipse are a chance coincidence. No clear evidence of disk wind is found.

  2. The Connection Between Reddening, Gas Covering Fraction, and the Escape of Ionizing Radiation at High Redshift

    NASA Astrophysics Data System (ADS)

    Reddy, Naveen A.; Steidel, Charles C.; Pettini, Max; Bogosavljević, Milan; Shapley, Alice E.

    2016-09-01

    Using a large sample of spectroscopically confirmed z∼ 3 galaxies, we establish an empirical relationship between reddening (E(B-V)), neutral gas covering fraction ({f}{{cov}}({{H}} {{I}})), and the escape of ionizing (Lyman continuum, LyC) photons. Our sample includes 933 galaxies at z∼ 3,121 of which have deep spectroscopic observations (≳ 7 hr) at 850≲ {λ }{{rest}}≲ 1300 Å with the Low Resolution Imaging Spectrograph on Keck. The high covering fraction of outflowing optically thick {{H}} {{I}} indicated by the composite spectra of these galaxies implies that photoelectric absorption, rather than dust attenuation, dominates the depletion of LyC photons. By modeling the composite spectra as the combination of an unattenuated stellar spectrum including nebular continuum emission with one that is absorbed by {{H}} {{I}} and reddened by a line-of-sight extinction, we derive an empirical relationship between E(B-V) and {f}{{cov}}({{H}} {{I}}). Galaxies with redder UV continua have larger covering fractions of {{H}} {{I}} characterized by higher line-of-sight extinctions. We develop a model which connects the ionizing escape fraction with E(B-V), and which may be used to estimate the ionizing escape fraction for an ensemble of galaxies. Alternatively, direct measurements of the escape fraction for our sample allow us to constrain the intrinsic LyC-to-UV flux density ratio to be < S(900 \\mathring{{A}} )/S(1500 \\mathring{{A}} ){> }{{int}}≳ 0.20, a value that favors stellar population models that include weaker stellar winds, a flatter initial mass function, and/or binary evolution. Last, we demonstrate how the framework discussed here may be used to assess the pathways by which ionizing radiation escapes from high-redshift galaxies. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous

  3. A reservoir of ionized gas in the galactic halo to sustain star formation in the Milky Way.

    PubMed

    Lehner, Nicolas; Howk, J Christopher

    2011-11-18

    Without a source of new gas, our Galaxy would exhaust its supply of gas through the formation of stars. Ionized gas clouds observed at high velocity may be a reservoir of such gas, but their distances are key for placing them in the galactic halo and unraveling their role. We have used the Hubble Space Telescope to blindly search for ionized high-velocity clouds (iHVCs) in the foreground of galactic stars. We show that iHVCs with 90 ≤ |v(LSR)| ≲ 170 kilometers per second (where v(LSR) is the velocity in the local standard of rest frame) are within one galactic radius of the Sun and have enough mass to maintain star formation, whereas iHVCs with |v(LSR)| ≳ 170 kilometers per second are at larger distances. These may be the next wave of infalling material.

  4. A reservoir of ionized gas in the galactic halo to sustain star formation in the Milky Way.

    PubMed

    Lehner, Nicolas; Howk, J Christopher

    2011-11-18

    Without a source of new gas, our Galaxy would exhaust its supply of gas through the formation of stars. Ionized gas clouds observed at high velocity may be a reservoir of such gas, but their distances are key for placing them in the galactic halo and unraveling their role. We have used the Hubble Space Telescope to blindly search for ionized high-velocity clouds (iHVCs) in the foreground of galactic stars. We show that iHVCs with 90 ≤ |v(LSR)| ≲ 170 kilometers per second (where v(LSR) is the velocity in the local standard of rest frame) are within one galactic radius of the Sun and have enough mass to maintain star formation, whereas iHVCs with |v(LSR)| ≳ 170 kilometers per second are at larger distances. These may be the next wave of infalling material. PMID:21868626

  5. Extended ionized gas in elliptical galaxies. II. Velocity and monochromatic maps of 11 elliptical and lenticular galaxies

    NASA Astrophysics Data System (ADS)

    Plana, H.; Boulesteix, J.; Amram, Ph.; Carignan, C.; Mendes de Oliveira, C.

    1998-02-01

    For the last ten years faint ionized gas detection has been carried out for elliptical galaxies with success. The kinematics is essential to understand galaxy gas origin and fate. Here we present a sample of 11 elliptical and lenticular galaxies observed with the ``Cigale" scanning Perot-Fabry instrument. For each galaxy monochromatic and velocity map of ionized gas is presented. Geometrical properties such as viewing angles and axis ratios are also derived from observations. Double gaseous components are found in 3 galaxies of our sample, implying an external origin for at least part of the observed gas. % Based on observations collected with the S.A.O. 6 m telescope located in Nizhnij Arkhyz (Russia), the 3.6 m CFH telescope and the 3.6 m telescope at ESO.

  6. Plasma ionization frequency, edge-to-axis density ratio, and density on axis of a cylindrical gas discharge

    SciTech Connect

    Palacio Mizrahi, J. H.

    2014-06-15

    A rigorous derivation of expressions, starting from the governing equations, for the ionization frequency, edge-to-axis ratio of plasma density, plasma density at the axis, and radially averaged plasma density in a cylindrical gas discharge has been obtained. The derived expressions are simple and involve the relevant parameters of the discharge: Cylinder radius, axial current, and neutral gas pressure. The found expressions account for ion inertia, ion temperature, and changes in plasma ion collisionality.

  7. Determination of BROMATE AT PARTS-PER-TRILLION LEVELS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH NEGATIVE CHEMICAL IONIZATION

    EPA Science Inventory

    The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS) following a bromate react...

  8. Direct gas-phase detection of nerve and blister warfare agents utilizing active capillary plasma ionization mass spectrometry.

    PubMed

    Wolf, J-C; Schaer, M; P Siegenthaler, P; Zenobi, R

    2015-01-01

    Ultrasensitive direct gas-phase detection of chemical warfare agents (CWAs) is demonstrated utilizing active capillary plasma ionization and triple quadrupole mass spectrometry (MS) instrumentation. Four G- agents, two V-agents and various blistering agents [including sulfur mustard (HD)] were detected directly in the gas phase with limits of detection in the low parts per trillion (ng m(-3)) range. The direct detection of HD was shown for dry carrier gas conditions, but signals vanished when humidity was present, indicating a possible direct detection of HD after sufficient gas phase pretreatment. The method provided sufficient sensitivity to monitor directly the investigated volatile CWAs way below their corresponding minimal effect dose, and in most cases even below the eight hours worker exposure concentration. In general, the ionization is very soft, with little to no in-source fragmentation. Especially for the G-agents, some dimer formation occurred at higher concentrations. This adds complexity, but also further selectivity, to the corresponding mass spectra. Our results show that the active capillary plasma ionization is a robust, sensitive, "plug and play" ambient ionization source suited (but not exclusively) to the very sensitive detection of CWAs. It has the potential to be used with portable MS instrumentation. PMID:26307710

  9. Dust trap formation in a non-self-sustained discharge with external gas ionization

    SciTech Connect

    Filippov, A. V. Babichev, V. N.; Pal’, A. F.; Starostin, A. N.; Cherkovets, V. E.; Rerikh, V. K.; Taran, M. D.

    2015-11-15

    Results from numerical studies of a non-self-sustained gas discharge containing micrometer dust grains are presented. The non-self-sustained discharge (NSSD) was controlled by a stationary fast electron beam. The numerical model of an NSSD is based on the diffusion drift approximation for electrons and ions and self-consistently takes into account the influence of the dust component on the electron and ion densities. The dust component is described by the balance equation for the number of dust grains and the equation of motion for dust grains with allowance for the Stokes force, gravity force, and electric force in the cathode sheath. The interaction between dust grains is described in the self-consistent field approximation. The height of dust grain levitation over the cathode is determined and compared with experimental results. It is established that, at a given gas ionization rate and given applied voltage, there is a critical dust grain size above which the levitation condition in the cathode sheath cannot be satisfied. Simulations performed for the dust component consisting of dust grains of two different sizes shows that such grains levitate at different heights, i.e., size separation of dust drains levitating in the cathode sheath of an NSSD takes place.

  10. Development of a Mesoscale Pulsed Discharge Helium Ionization Detector for Portable Gas Chromatography.

    PubMed

    Manginell, Ronald P; Mowry, Curtis D; Pimentel, Adam S; Mangan, Michael A; Moorman, Matthew W; Sparks, Elizabeth S; Allen, Amy; Achyuthan, Komandoor E

    2015-01-01

    Miniaturization of gas chromatography (GC) instrumentation enables field detection of volatile organic compounds (VOCs) for chembio-applications such as clandestine human transport and disease diagnostics. We fabricated a mesoscale pulsed discharge helium ionization detector (micro-PDHID) for integrating with our previously described mini-GC hardware. Stainless steel electrodes fabricated by photochemical etching and electroforming facilitated rapid prototyping and enabled nesting of inter-electrode insulators for self-alignment of the detector core during assembly. The prototype was ∼10 cm(3) relative to >400 cm(3) of a commercial PDHID, but with a comparable time to sweep a VOC peak from the detector cell (170 ms and 127 ms, respectively). Electron trajectory modeling, gas flow rate, voltage bias, and GC outlet location were optimized for improving sensitivity. Despite 40-fold miniaturization, the micro-PDHID detected 18 ng of the human emanation, 3-methyl-2-hexenoic acid with <3-fold decrease in sensitivity relative to the commercial detector. The micro-PDHID was rugged and operated for 9 months without failure. PMID:26561264

  11. Numerical studies of the behavior of ionized residual gas in an energy recovering linac

    NASA Astrophysics Data System (ADS)

    Pöplau, Gisela; van Rienen, Ursula; Meseck, Atoosa

    2015-04-01

    Next generation light sources such as energy recovering linacs (ERLs) are highly sensitive to instabilities due to ionized residual gas, which must be mitigated for successful operation. Vacuum pumps are insufficient for removal of the ions, as the ions are trapped by the beam's electrical potential. Two effective measures are (i) introducing clearing gaps in the bunch train, and (ii) installing clearing electrodes which pull out the trapped ions from the electrical potential of the beam. In this paper, we present numerical studies on the behavior of ion clouds that interact with bunch trains in an ERL taking into account the effects of the clearing gaps and clearing electrodes. We present simulations with different compositions of the residual gas. Simulations are done using the MOEVE PIC Tracking software package developed at Rostock University, which has been upgraded to include the behavior of ion clouds in the environment of additional electromagnetic fields, such as generated by clearing electrodes. The simulations use the parameters of the Berlin Energy Recovery Linac Project (bERLinPro) to allow for the deduction of appropriate measures for bERLinPro 's design and operation.

  12. Initial velocity of secondary ions from XY-TOF technique, simultaneous calibration by residual gas ionization

    NASA Astrophysics Data System (ADS)

    Jalowy, T.; Weber, Th; Dörner, R.; Farenzena, L.; Collado, V. M.; da Silveira, E. F.; Schmidt-Böcking, H.; Groeneveld, K. O.

    2004-01-01

    A crucial parameter to distinguish the prompt secondary ion emission from surfaces after particle impact from the delayed one is T0(m/q), the time-of-flight (TOF) of ions with a given mass m and charge q "emitted" with zero velocity. This quantity is also an important reference for the measurement of prompt ion emission velocity distribution. Presented is a novel and accurate method to determine T0(m/q), based on position sensitive XY-TOF analysis of residual gas ionization along the projectile trajectory, which is a low-pressure version of the traditional cloud chamber technique. Measurements using a mixture of He, Ne and Ar gases at low pressure (10-5 mbar) were performed to illustrate this new T0-gas target calibration method. Secondary ion emission of Hn+, CnHn+ and Li+ ions from C, Al and LiF targets, bombarded by MeV Ar0 and N0 projectiles, is analyzed. It is found that, in contrast to Li+, hydrogen and hydrocarbon ions are always promptly emitted. The initial velocity distribution of H2+ is determined and discussed.

  13. Dust trap formation in a non-self-sustained discharge with external gas ionization

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Babichev, V. N.; Pal', A. F.; Starostin, A. N.; Cherkovets, V. E.; Rerikh, V. K.; Taran, M. D.

    2015-11-01

    Results from numerical studies of a non-self-sustained gas discharge containing micrometer dust grains are presented. The non-self-sustained discharge (NSSD) was controlled by a stationary fast electron beam. The numerical model of an NSSD is based on the diffusion drift approximation for electrons and ions and self-consistently takes into account the influence of the dust component on the electron and ion densities. The dust component is described by the balance equation for the number of dust grains and the equation of motion for dust grains with allowance for the Stokes force, gravity force, and electric force in the cathode sheath. The interaction between dust grains is described in the self-consistent field approximation. The height of dust grain levitation over the cathode is determined and compared with experimental results. It is established that, at a given gas ionization rate and given applied voltage, there is a critical dust grain size above which the levitation condition in the cathode sheath cannot be satisfied. Simulations performed for the dust component consisting of dust grains of two different sizes shows that such grains levitate at different heights, i.e., size separation of dust drains levitating in the cathode sheath of an NSSD takes place.

  14. Development of a Mesoscale Pulsed Discharge Helium Ionization Detector for Portable Gas Chromatography.

    PubMed

    Manginell, Ronald P; Mowry, Curtis D; Pimentel, Adam S; Mangan, Michael A; Moorman, Matthew W; Sparks, Elizabeth S; Allen, Amy; Achyuthan, Komandoor E

    2015-01-01

    Miniaturization of gas chromatography (GC) instrumentation enables field detection of volatile organic compounds (VOCs) for chembio-applications such as clandestine human transport and disease diagnostics. We fabricated a mesoscale pulsed discharge helium ionization detector (micro-PDHID) for integrating with our previously described mini-GC hardware. Stainless steel electrodes fabricated by photochemical etching and electroforming facilitated rapid prototyping and enabled nesting of inter-electrode insulators for self-alignment of the detector core during assembly. The prototype was ∼10 cm(3) relative to >400 cm(3) of a commercial PDHID, but with a comparable time to sweep a VOC peak from the detector cell (170 ms and 127 ms, respectively). Electron trajectory modeling, gas flow rate, voltage bias, and GC outlet location were optimized for improving sensitivity. Despite 40-fold miniaturization, the micro-PDHID detected 18 ng of the human emanation, 3-methyl-2-hexenoic acid with <3-fold decrease in sensitivity relative to the commercial detector. The micro-PDHID was rugged and operated for 9 months without failure.

  15. The Properties and the Evolution of the Highly Ionized Gas in MR 2251-178

    NASA Technical Reports Server (NTRS)

    Kaspi, Shai; Netzer, hagai; Chelouche, Doron; George, Ian M.; Nandra, Kirpal; Turner, T. J.

    2004-01-01

    We present the first XMM-Newton observations of the radio-quiet quasar MR 2251-178 obtained in 2000 and 2002. The EPIC-pn spectra show a power-law continuum with a slope of Gamma = 1.6 at high energies absorbed by at least two warm absorbers (WAs) intrinsic to the source. The underlying continuum in the earlier observation shows a soft excess at low X-ray energies which can be modeled as an additional power-law with Gamma = 2.9. The spectra also show a weak narrow iron K alpha emission line. The high-resolution grating spectrum obtained in 2002 shows emission lines from N VI, O VII, O VIII, Ne IX, and Ne X, as well as absorption lines from the low-ionization ions of O III, O IV, and O V, and other confirmed and suspected weaker absorption lines. The O III - O V lines are consistent with the properties of the emission line gas observed as extended optical (O III) emission in this source. The signal-to-noise of the 2000 grating data is too low to detect any lines. We suggest a model for the high-resolution spectrum which consist of two or three warm-absorber (WA) components. The two-components model has a high-ionization WA with a column density of 10(exp 21.5)-10 (exp 21.8) sq cm and a low-ionization absorber with a column density of 10(exp 20.3) sq cm. In the three-components model we add a lower ionization component that produces the observed iron M-shell absorption lines. We investigate the spectral variations in MR 2251-178 over a period of 8.5 years using data from ASCA, BeppoSAX, and XMM-Newton. All X-ray observations can be fitted with the above two power laws and the two absorbers. The observed luminosity variations seems to correlate with variations in the soft X-ray continuum. The 8.5 year history of the source suggests a changing X-ray absorber due to material that enters and disappears from the line-of-sight on timescales of several months. We also present, for the first time, the entire FUSE spectrum of MR 2251-178. We detect emission from N III, C III

  16. POLYCYCLIC AROMATIC HYDROCARBONS, IONIZED GAS, AND MOLECULAR HYDROGEN IN BRIGHTEST CLUSTER GALAXIES OF COOL-CORE CLUSTERS OF GALAXIES

    SciTech Connect

    Donahue, Megan; Mark Voit, G.; Hoffer, Aaron; De Messieres, Genevieve E.; O'Connell, Robert W.; McNamara, Brian R.; Nulsen, Paul E. J. E-mail: voit@pa.msu.edu

    2011-05-01

    We present measurements of 5-25 {mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of nine cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray-emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission-line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H{sub 2} rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {mu}m/24 {mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.

  17. Very metal-poor galaxies: ionized gas kinematics in nine objects

    NASA Astrophysics Data System (ADS)

    Moiseev, A. V.; Pustilnik, S. A.; Kniazev, A. Y.

    2010-07-01

    The study of ionized gas morphology and kinematics in nine extremely metal-deficient (XMD) galaxies with the scanning Fabry-Perot interferometer on the Special Astrophysical Observatory (SAO) 6-m telescope is presented. Some of these very rare objects (with currently known range of O/H of 7.12 < 12 + log(O/H) < 7.65, or ) are believed to be the best proxies of `young' low-mass galaxies in the high-redshift Universe. One of the main goals of this study is to look for possible evidence of star formation (SF) activity induced by external perturbations. Recent results from HI mapping of a small subsample of XMD star-forming galaxies provided confident evidence for the important role of interaction-induced SF. Our observations provide complementary or new information that the great majority of the studied XMD dwarfs have strongly disturbed gas morphology and kinematics or the presence of detached components. We approximate the observed velocity fields by simple models of a rotating tilted thin disc, which allows us the robust detection of non-circular gas motions. These data, in turn, indicate the important role of current/recent interactions and mergers in the observed enhanced SF. As a by-product of our observations, we obtained data for two Low Surface Brightness (LSB) dwarf galaxies: Anon J012544+075957 that is a companion of the merger system UGC 993, and SAO 0822+3545 which shows off-centre, asymmetric, low star formation rate star-forming regions, likely induced by the interaction with the companion XMD dwarf HS 0822+3542. Based on observations obtained with the Special Astrophysical Observatory RAS 6-m telescope. E-mail: moisav@gmail.com (AVM); sap@sao.ru (SAP); akniazev@saao.ac.za (AYK)

  18. IZI: INFERRING THE GAS PHASE METALLICITY (Z) AND IONIZATION PARAMETER (q) OF IONIZED NEBULAE USING BAYESIAN STATISTICS

    SciTech Connect

    Blanc, Guillermo A.; Kewley, Lisa; Vogt, Frédéric P. A.; Dopita, Michael A.

    2015-01-10

    We present a new method for inferring the metallicity (Z) and ionization parameter (q) of H II regions and star-forming galaxies using strong nebular emission lines (SELs). We use Bayesian inference to derive the joint and marginalized posterior probability density functions for Z and q given a set of observed line fluxes and an input photoionization model. Our approach allows the use of arbitrary sets of SELs and the inclusion of flux upper limits. The method provides a self-consistent way of determining the physical conditions of ionized nebulae that is not tied to the arbitrary choice of a particular SEL diagnostic and uses all the available information. Unlike theoretically calibrated SEL diagnostics, the method is flexible and not tied to a particular photoionization model. We describe our algorithm, validate it against other methods, and present a tool that implements it called IZI. Using a sample of nearby extragalactic H II regions, we assess the performance of commonly used SEL abundance diagnostics. We also use a sample of 22 local H II regions having both direct and recombination line (RL) oxygen abundance measurements in the literature to study discrepancies in the abundance scale between different methods. We find that oxygen abundances derived through Bayesian inference using currently available photoionization models in the literature can be in good (∼30%) agreement with RL abundances, although some models perform significantly better than others. We also confirm that abundances measured using the direct method are typically ∼0.2 dex lower than both RL and photoionization-model-based abundances.

  19. Self-injection and acceleration of electrons during ionization of gas atoms by a short laser pulse

    SciTech Connect

    Singh, K.P.

    2006-04-15

    Using a relativistic three-dimensional single-particle code, acceleration of electrons created during the ionization of nitrogen and oxygen gas atoms by a laser pulse has been studied. Barrier suppression ionization model has been used to calculate ionization time of the bound electrons. The energy gained by the electrons peaks for an optimum value of laser spot size. The electrons created near the tail do not gain sufficient energy for a long duration laser pulse. The electrons created at the tail of pulse escape before fully interacting with the trailing part of the pulse for a short duration laser pulse, which causes electrons to retain sufficient energy. If a suitable frequency chirp is introduced then energy of the electrons created at the tail of the pulse further increases.

  20. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  1. Integral Field Unit Observations of NGC 4302: Kinematics of the Diffuse Ionized Gas Halo

    NASA Astrophysics Data System (ADS)

    Heald, George H.; Rand, Richard J.; Benjamin, Robert A.; Bershady, Matthew A.

    2007-07-01

    We present moderate-resolution spectroscopy of extraplanar diffuse ionized gas (EDIG) emission in the edge-on spiral galaxy NGC 4302. The spectra were obtained with the SparsePak integral field unit (IFU) at the WIYN Observatory. The wavelength coverage of the observations includes the [N II] λ6548, 6583, Hα, and [S II] λ6716, 6731 emission lines. The spatial coverage of the IFU includes the entirety of the EDIG emission noted in previous imaging studies of this galaxy. The spectra are used to construct position-velocity (PV) diagrams at several ranges of heights above the midplane. Azimuthal velocities are directly extracted from the PV diagrams using the envelope-tracing method and indicate an extremely steep drop-off in rotational velocity with increasing height, with magnitude ~30 km s-1 kpc-1. We find evidence for a radial variation in the velocity gradient on the receding side. We have also performed artificial observations of galaxy models in an attempt to match the PV diagrams. The results of a statistical analysis also favor a gradient of ~30 km s-1 kpc-1. We compare these results with an entirely ballistic model of disk-halo flow and find a strong dichotomy between the observed kinematics and those predicted by the model. The disagreement is worse than we have found for other galaxies in previous studies. The conclusions of this paper are compared to results for two other galaxies, NGC 5775 and NGC 891. We find that the vertical gradient in rotation speed, per unit EDIG scale height, for all three galaxies is consistent with a constant magnitude (within the errors) of approximately 15-25 km s-1 per scale height, independent of radius. This relationship is also true within the galaxy NGC 4302. We also discuss how the gradient depends on the distribution and morphology of the EDIG and the star formation rates of the galaxies, and consequences for the origin of the gas.

  2. Diffuse gas in retired galaxies: nebular emission templates and constraints on the sources of ionization

    NASA Astrophysics Data System (ADS)

    Johansson, Jonas; Woods, Tyrone E.; Gilfanov, Marat; Sarzi, Marc; Chen, Yan-Mei; Oh, Kyuseok

    2016-10-01

    We present emission-line templates for passively-evolving (`retired') galaxies, useful for investigation of the evolution of the interstellar medium in these galaxies, and characterization of their high-temperature source populations. The templates are based on high signal-to-noise (>800) co-added spectra (3700-6800 Å) of ˜11 500 gas-rich Sloan Digital Sky Survey galaxies devoid of star formation and active galactic nuclei. Stacked spectra are provided for the entire sample and sub-samples binned by mean stellar age. In our previous paper, Johansson et al., these spectra provided the first measurements of the He II 4686 Å line in passively-evolving galaxies, and the observed He II/Hβ ratio constrained the contribution of accreting white dwarfs (the `single-degenerate' scenario) to the Type Ia supernova rate. In this paper, the full range of unambiguously detected emission lines are presented. Comparison of the observed [O I] 6300 Å/Hα ratio with photoionization models further constrains any high-temperature single-degenerate scenario for Type Ia supernovae (with 1.5 ≲ T/105 K ≲ 10) to ≲3-6 per cent of the observed rate in the youngest age bin (i.e. highest SN Ia rate). Hence, for the same temperatures, in the presence of an ambient population of post-asymptotic giant branch stars, we exclude additional high-temperature sources with a combined ionizing luminosity of ≈1.35 × 1030 L⊙/M⊙,* for stellar populations with mean ages of 1-4 Gyr. Furthermore, we investigate the extinction affecting both the stellar and nebular continuum. The latter shows about five times higher values. This contradicts isotropically distributed dust and gas that renders similar extinction values for both cases.

  3. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    PubMed Central

    Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-01-01

    Abstract Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  4. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    PubMed Central

    Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-01-01

    Abstract Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit. PMID:27610289

  5. BTEX determination in water matrices using HF-LPME with gas chromatography-flame ionization detector.

    PubMed

    Sarafraz-Yazdi, A; Amiri, A H; Es'haghi, Z

    2008-03-01

    In the present work, a sample pre-treatment technique for the determination of trace concentrations of benzene, toluene, ethyl benzene and xylene (BTEX) in aqueous samples has been developed and applied to analysis of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow-fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame ionization detection (GC-FID). The effective parameters such as organic solvent, extraction time, agitation speed and salting effect were investigated. Good reproducibilities of the extraction performance were obtained, with the RSD values ranging from 2.02 to 4.61% (n=5). The method provided 41.47-128.01 fold preconcentration of the target analytes. The limits of detections for the BTEX were in the range of 0.005-03microg ml(-1). In addition, sample clean-up was achieved during LPME due to the selectivity of the hollow fiber, which prevented undesirable large molecules from being extracted. Real samples (River and waste waters) containing BTEX were examined using this method with good linearity and precision (RSDs most lower than 6.00%, n=5). All experiments were carried out at room temperature, 22+/-0.5 degrees C.

  6. Hα and [SII] Emission from Warm Ionized Gas in the Scutum-Centaurus Arm

    NASA Astrophysics Data System (ADS)

    Hill, Alex S.; Benjamin, Robert A.; Haffner, L. Matthew; Gostisha, Martin C.; Barger, Kathleen A.

    2014-06-01

    We present Wisconsin H-Alpha Mapper [SII] λ6716 and Hα spectroscopic maps of the warm ionized medium (WIM) in the Scutum-Centaurus Arm at Galactic longitudes 310° < l < 345°. Using extinction-corrected Hα intensities (I_{{H} \\alpha }^c), we measure an exponential scale height of electron density squared in the arm of H_{n_e^2}= 0.30 \\, {kpc} (assuming a distance of 3.5 kpc), intermediate between that observed in the inner Galaxy and in the Perseus Arm. The [S II]/Hα line ratio is enhanced at large |z| and in sightlines with faint I_{{H} \\alpha }^c. We find that the [S II]/Hα line ratio has a power-law relationship with I_{{H} \\alpha }^c from a value of ≈1.0 at I_{{H} \\alpha }^c< 0.2 \\, {R} (Rayleighs) to a value of ≈0.08 at I_{{H} \\alpha }^c\\gtrsim 100 \\, {R}. The line ratio is better correlated with Hα intensity than with height above the plane, indicating that the physical conditions within the WIM vary systematically with electron density. We argue that the variation of the line ratio with height is a consequence of the decrease of electron density with height. Our results reinforce the well-established picture in which the diffuse Hα emission is due primarily to emission from in situ photoionized gas, with scattered light only a minor contributor.

  7. Aerial surveillance for gas and liquid hydrocarbon pipelines using a flame ionization detector (FID)

    SciTech Connect

    Riquetti, P.V.; Fletcher, J.I.; Minty, C.D.

    1996-12-31

    A novel application for the detection of airborne hydrocarbons has been successfully developed by means of a highly sensitive, fast responding Flame Ionization Detector (FID). The traditional way to monitor pipeline leaks has been by ground crews using specific sensors or by airborne crews highly trained to observe anomalies associated with leaks during periodic surveys of the pipeline right-of-way. The goal has been to detect leaks in a fast and cost effective way before the associated spill becomes a costly and hazardous problem. This paper describes a leak detection system combined with a global positioning system (GPS) and a computerized data output designed to pinpoint the presence of hydrocarbons in the air space of the pipeline`s right of way. Fixed wing aircraft as well as helicopters have been successfully used as airborne platforms. Natural gas, crude oil and finished products pipelines in Canada and the US have been surveyed using this technology with excellent correlation between the aircraft detection and in situ ground detection. The information obtained is processed with a proprietary software and reduced to simple coordinates. Results are transferred to ground crews to effect the necessary repairs.

  8. Terahertz ionization of highly charged quantum posts in a perforated electron gas.

    PubMed

    Morris, Christopher M; Stehr, Dominik; Kim, Hyochul; Truong, Tuan-Anh; Pryor, Craig; Petroff, Pierre M; Sherwin, Mark S

    2012-03-14

    "Quantum posts" are roughly cylindrical semiconductor nanostructures that are embedded in an energetically shallower "matrix" quantum well of comparable thickness. We report measurements of voltage-controlled charging and terahertz absorption of 30 nm thick InGaAs quantum wells and posts. Under flat-band (zero-electric field) conditions, the quantum posts each contain approximately six electrons, and an additional ~2.4 × 10(11) cm(-2) electrons populate the quantum well matrix. In this regime, absorption spectra show peaks at 3.5 and 4.8 THz (14 and 19 meV) whose relative amplitude depends strongly on temperature. These peaks are assigned to intersubband transitions of electrons in the quantum well matrix. A third, broader feature has a temperature-independent amplitude and is assigned to an absorption involving quantum posts. Eight-band k·p calculations incorporating the effects of strain and Coulomb repulsion predict that the electrons in the posts strongly repel the electrons in the quantum well matrix, "perforating" the electron gas. The strongest calculated transition, which has a frequency close to the center of the quantum post related absorption at 5 THz (20 meV), is an ionizing transition from a filled state to a quasi-bound state that can easily scatter to empty states in the quantum well matrix.

  9. Mass spectrometric evaluation of the gas phase structure of noncovalent quadruplex DNA obtained by electrospray ionization

    SciTech Connect

    Edmonds, C.G.; Cheng, Xueheng; Bakhtiar, R.; Van Orden, S.; Smith, R.D.; Schlegel, C.; Camp, D.G. II

    1994-12-31

    A number of quanine-rich DNA sequences have been recognized which assemble into quadrupole-helical non-Watson/Crick hybridized structures. These sequences have been localized in a number of key regions in chromosomal DNA including telomers and transcriptional promoters. The preservation of this tetrameric association in the gas phase following electrospray ionization (ESI) has been reported in this laboratory. The authors have extended these studies by the preparation of four candidate quadruplex oligomers. Three of these (I, 5{prime}-dCGC GGG GCG-3{prime}; II, 5{prime}dCGC GGGG GCG-3{prime} and III, 5{prime}-dCGC GGGGG GCG-3{prime}) differ in the number of quanine residues available for G-quartet stacking in the quadruplex array and a fourth (HG, 5{prime}-dCGC AGGG GCG03{prime}) is a sequence prominent in human telomeric DNA. During their preparation, the authors observed remarkable stability of the multimeric species in the condensed phase including intact migration in HPLC under apparently {open_quotes}denaturing{close_quotes} conditions. Under standard conditions (aqueous solution of oligonucleotide samples and nozzle-skimmer interface) on a linear quadrupole mass spectrometer oligonucleotide samples showed the typical distribution of charge states for unassociated oligonucleotides. ESI from phosphate-EDTA buffered solutions with the utilization of a capillary/skimmer interface arrangement which provides mild conditions for transfer of ions through the atmosphere/vacuum interface afforded spectra which show prominent contributions from species with quadrupole stoichiometry together monomeric materials.

  10. Ethanol analysis by headspace gas chromatography with simultaneous flame-ionization and mass spectrometry detection.

    PubMed

    Tiscione, Nicholas B; Alford, Ilene; Yeatman, Dustin Tate; Shan, Xiaoqin

    2011-09-01

    Ethanol is the most frequently identified compound in forensic toxicology. Although confirmation involving mass spectrometry is desirable, relatively few methods have been published to date. A novel technique utilizing a Dean's Switch to simultaneously quantitate and confirm ethyl alcohol by flame-ionization (FID) and mass spectrometric (MS) detection after headspace sampling and gas chromatographic separation is presented. Using 100 μL of sample, the limits of detection and quantitation were 0.005 and 0.010 g/dL, respectively. The zero-order linear range (r(2) > 0.990) was determined to span the concentrations of 0.010 to 1.000 g/dL. The coefficient of variation of replicate analyses was less than 3.1%. Quantitative accuracy was within ±8%, ±6%, ±3%, and ±1.5% at concentrations of 0.010, 0.025, 0.080, and 0.300 g/dL, respectively. In addition, 1,1-difluoroethane was validated for qualitative identification by this method. The validated FID-MS method provides a procedure for the quantitation of ethyl alcohol in blood by FID with simultaneous confirmation by MS and can also be utilized as an identification method for inhalants such as 1,1-difluoroethane. PMID:21871160

  11. BTEX determination in water matrices using HF-LPME with gas chromatography-flame ionization detector.

    PubMed

    Sarafraz-Yazdi, A; Amiri, A H; Es'haghi, Z

    2008-03-01

    In the present work, a sample pre-treatment technique for the determination of trace concentrations of benzene, toluene, ethyl benzene and xylene (BTEX) in aqueous samples has been developed and applied to analysis of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow-fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame ionization detection (GC-FID). The effective parameters such as organic solvent, extraction time, agitation speed and salting effect were investigated. Good reproducibilities of the extraction performance were obtained, with the RSD values ranging from 2.02 to 4.61% (n=5). The method provided 41.47-128.01 fold preconcentration of the target analytes. The limits of detections for the BTEX were in the range of 0.005-03microg ml(-1). In addition, sample clean-up was achieved during LPME due to the selectivity of the hollow fiber, which prevented undesirable large molecules from being extracted. Real samples (River and waste waters) containing BTEX were examined using this method with good linearity and precision (RSDs most lower than 6.00%, n=5). All experiments were carried out at room temperature, 22+/-0.5 degrees C. PMID:18221982

  12. Determination of 17 β-Estradiol in Rabbit Plasma by Gas Chromatography with Flame Ionization Detection

    PubMed Central

    Yilmaz, B; Kadioglu, Y.

    2012-01-01

    This article describes gas chromatography-flame ionization detection method for determination of 17 β-estradiol in rabbit plasma. 17 β-estradiol and internal standard progesterone were extracted from plasma using liquid–liquid extraction method. Linearity was found between 0.25 and 20 μg/ml (r2=0.994) for plasma samples. Intra-day and inter-day precision, expressed as the relative standard deviation were less than 5.5%, and accuracy (relative error) was less than 3.5%. The mean recovery of 17 β-estradiol samples was 94.4%. The limits of detection and quantification of method for plasma samples were 0.10 μg/ml and 0.15 μg/ml, respectively. Also, clinically used other 10 drugs were investigated to check for potential interferences and the method was successfully applied to the determination of 17 β-estradiol in New Zealand white rabbits. PMID:23439655

  13. Ionized Gas Kinematics at High Resolution. IV. Star Formation and a Rotating Core in the Medusa (NGC 4194)

    NASA Astrophysics Data System (ADS)

    Beck, Sara C.; Lacy, John; Turner, Jean; Greathouse, Thomas; Neff, Susan

    2014-05-01

    NGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features. We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0.''18 (35 pc) and a 12.8 μm [Ne II] data cube with spectral resolution ~4 km s-1: the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.

  14. Ionized Gas Kinematics at High Resolution. IV. Star Formation and a Rotating Core in the Medusa (NGC 4194)

    NASA Technical Reports Server (NTRS)

    Beck, Sara C.; Lacy, John; Neff, Susan Gale; Turner, Jean; Greathouse, Thomas; Neff, Susan

    2014-01-01

    NGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features.We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0".18 (35 pc) and a 12.8 micron [Ne II] data cube with spectral resolution approx. 4 km/s: the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.

  15. Identification of Guest-Host Inclusion Complexes in the Gas Phase by Electrospray Ionization-Mass Spectrometry

    ERIC Educational Resources Information Center

    Mendes, De´bora C.; Ramamurthy, Vaidhyanathan; Da Silva, Jose´ P.

    2015-01-01

    In this laboratory experiment, students follow a step-by-step procedure to prepare and study guest-host complexes in the gas phase using electrospray ionization-mass spectrometry (ESI-MS). Model systems are the complexes of hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) with the guest 4-styrylpyridine (SP). Aqueous solutions of CB7 or CB8…

  16. STARS AND IONIZED GAS IN THE S0 GALAXY NGC 7743: AN INCLINED LARGE-SCALE GASEOUS DISK

    SciTech Connect

    Katkov, Ivan Yu.; Sil'chenko, Olga K.; Moiseev, Alexei V. E-mail: moisav@gmail.com

    2011-10-20

    We used deep, long-slit spectra and integral-field spectral data to study the stars, ionized gas kinematics, and stellar population properties in the lenticular barred galaxy NGC 7743. We show that ionized gas at distances larger than 1.5 kpc from the nucleus settles in the disk, which is significantly inclined toward the stellar disk of the galaxy. Making different assumptions about the geometry of the disks and including different sets of emission lines in the fitting, under the assumption of thin, flat-disk circular rotation, we obtain the full possible range of angles between the disks to be 34{sup 0} {+-} 9{sup 0} or 77{sup 0} {+-} 9{sup 0}. The most probable origin of the inclined disk is the external gas accretion from a satellite orbiting the host galaxy, with a corresponding angular momentum direction. The published data on the H I distribution around NGC 7743 suggest that the galaxy has a gas-rich environment. The emission-line ratio diagrams imply the domination of shock waves in the ionization state of the gaseous disk, whereas the contribution of photoionization from recent star formation seems to be negligible. In some parts of the disk, a difference between the velocities of the gas emitting from the forbidden lines and Balmer lines is detected. This may be caused by the mainly shock-excited inclined disk, whereas some fraction of the Balmer-line emission is produced by a small amount of gas excited by young stars in the main stellar disk of NGC 7743. In the circumnuclear region (R < 200 pc), some evidence of the active galactic nucleus jet's interaction with an ambient interstellar medium was found.

  17. A new in-gas-laser ionization and spectroscopy laboratory for off-line studies at KU Leuven

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Yu.; Creemers, P.; Ferrer, R.; Granados, C.; Gaffney, L. P.; Huyse, M.; Mogilevskiy, E.; Raeder, S.; Sels, S.; Van den Bergh, P.; Van Duppen, P.; Zadvornaya, A.

    2016-06-01

    The in-gas laser ionization and spectroscopy (IGLIS) technique is used to produce and to investigate short-lived radioactive isotopes at on-line ion beam facilities. In this technique, the nuclear reaction products recoiling out of a thin target are thermalized and neutralized in a high-pressure noble gas, resonantly ionized by the laser beams in a two-step process, and then extracted from the ion source to be finally accelerated and mass separated. Resonant ionization of radioactive species in the supersonic gas jet ensures very high spectral resolution because of essential reduction of broadening mechanisms. To obtain the maximum efficiency and the best spectral resolution, properties of the supersonic jet and the laser beams must be optimized. To perform these studies a new off-line IGLIS laboratory, including a new high-repetition-rate laser system and a dedicated off-line mass separator, has been commissioned. In this article, the specifications of the different components necessary to achieve optimum conditions in laser-spectroscopy studies of radioactive beams using IGLIS are discussed and the results of simulations are presented.

  18. Double ionization of rare-gas dimers: NeKr+e. -->. NeKr/sup 2 +/

    SciTech Connect

    Stephan, K.; Maerk, T.D.; Helm, H.

    1982-11-01

    The existence of the doubly charged dimer ion NeKr/sup 2 +/ is substantiated by electron-impact ionization of the mixed van der Waals dimer NeKr. The stability of this doubly charged molecule is discussed with the use of semiquantative potential energy curves. The electron-impact-ionization appearance potential confirms the prediction from the potential-energy curves.

  19. Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

    PubMed

    Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

    2015-09-01

    Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS.

  20. Discovery of nine extended ionized gas clouds in a z = 0.4 cluster

    SciTech Connect

    Yagi, Masafumi; Koyama, Yusei; Kodama, Tadayuki; Gu, Liyi; Nakata, Fumiaki; Hattori, Takashi; Yoshida, Michitoshi

    2015-02-01

    From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (<2.3 arcmin ∼ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst galaxies, all of which are spectroscopically confirmed members of the cluster. Four out of the nine parent galaxies show distortion of stellar distribution in the disk, which can be a sign of recent interaction, and the interaction may have made the EIGs. On the other hand, six parent galaxies (one overlaps those exhibiting distortion) show Hα emission without stars, which implies ram pressure stripping. The spectrum of the brightest parent galaxy shows a post-starburst signature and resembles the Hα stripped galaxies found in the Coma cluster. Meanwhile, two brightest parent galaxies in A851 are more massive than the EIG parent galaxies in the Coma cluster. This is consistent with a “downsizing” of star-forming galaxies, though it is still within the statistical variance. We also analyzed Suprime-Cam data of another z=0.39 cluster, CL0024+17, but found no EIGs. The key difference between A851 and CL0024+17 would be the existence of a subcluster colliding with the main body of A851, in which six or seven out of the nine parent galaxies in A851 exist, and the fraction of EIGs in the subcluster is significantly higher than the main subcluster of A851 and CL0024+17.

  1. The Survey for Ionization in Neutral Gas Galaxies. I. Description and Initial Results

    NASA Astrophysics Data System (ADS)

    Meurer, Gerhardt R.; Hanish, D. J.; Ferguson, H. C.; Knezek, P. M.; Kilborn, V. A.; Putman, M. E.; Smith, R. C.; Koribalski, B.; Meyer, M.; Oey, M. S.; Ryan-Weber, E. V.; Zwaan, M. A.; Heckman, T. M.; Kennicutt, R. C., Jr.; Lee, J. C.; Webster, R. L.; Bland-Hawthorn, J.; Dopita, M. A.; Freeman, K. C.; Doyle, M. T.; Drinkwater, M. J.; Staveley-Smith, L.; Werk, J.

    2006-07-01

    We introduce the Survey for Ionization in Neutral Gas Galaxies (SINGG), a census of star formation in H I-selected galaxies. The survey consists of Hα and R-band imaging of a sample of 468 galaxies selected from the H I Parkes All Sky Survey (HIPASS). The sample spans three decades in H I mass and is free of many of the biases that affect other star-forming galaxy samples. We present the criteria for sample selection, list the entire sample, discuss our observational techniques, and describe the data reduction and calibration methods. This paper focuses on 93 SINGG targets whose observations have been fully reduced and analyzed to date. The majority of these show a single emission line galaxy (ELG). We see multiple ELGs in 13 fields, with up to four ELGs in a single field. All of the targets in this sample are detected in Hα, indicating that dormant (non-star-forming) galaxies with MHI>~3×107 Msolar are very rare. A database of the measured global properties of the ELGs is presented. The ELG sample spans 4 orders of magnitude in luminosity (Hα and R band), and Hα surface brightness, nearly 3 orders of magnitude in R surface brightness and nearly 2 orders of magnitude in Hα equivalent width (EW). The surface brightness distribution of our sample is broader than that of the Sloan Digital Sky Survey (SDSS) spectroscopic sample, the EW distribution is broader than prism-selected samples, and the morphologies found include all common types of star-forming galaxies (e.g., irregular, spiral, blue compact dwarf, starbursts, merging and colliding systems, and even residual star formation in S0 and Sa spirals). Thus, SINGG presents a superior census of star formation in the local universe suitable for further studies ranging from the analysis of H II regions to determination of the local cosmic star formation rate density.

  2. SIGGMA: A SURVEY OF IONIZED GAS IN THE GALAXY, MADE WITH THE ARECIBO TELESCOPE

    SciTech Connect

    Liu, B.; McIntyre, T.; Terzian, Y.; Minchin, R.; Anderson, L.; Churchwell, E.; Lebron, M.; Roshi, D. Anish

    2013-10-01

    A Survey of Ionized Gas in the Galaxy, made with the Arecibo telescope (SIGGMA), uses the Arecibo L-band Feed Array (ALFA) to fully sample the Galactic plane (30 Degree-Sign {<=} l {<=} 75 Degree-Sign and -2 Degree-Sign {<=} b {<=} 2 Degree-Sign ; 175 Degree-Sign {<=} l {<=} 207 Degree-Sign and -2 Degree-Sign {<=} b {<=} 1 Degree-Sign ) observable with the telescope in radio recombination lines (RRLs). Processed data sets are being produced in the form of data cubes of 2 Degree-Sign (along l) Multiplication-Sign 4 Degree-Sign (along b) Multiplication-Sign 151 (number of channels), archived and made public. The 151 channels cover a velocity range of 600 km s{sup -1} and the velocity resolution of the survey changes from 4.2 km s{sup -1} to 5.1 km s{sup -1} from the lowest frequency channel to the highest frequency channel. RRL maps with 3.'4 resolution and a line flux density sensitivity of {approx}0.5 mJy will enable us to identify new H II regions, measure their electron temperatures, study the physics of photodissociation regions with carbon RRLs, and investigate the origin of the extended low-density medium. Twelve Hn{alpha} lines fall within the 300 MHz bandpass of ALFA; they are resampled to a common velocity resolution to improve the signal-to-noise ratio (S/N) by a factor of three or more and preserve the line width. SIGGMA will produce the most sensitive fully sampled RRL survey to date. Here, we discuss the observing and data reduction techniques in detail. A test observation toward the H II region complex S255/S257 has detected Hn{alpha} and Cn{alpha} lines with S/N > 10.

  3. Discovery of Nine Extended Ionized Gas Clouds in a z = 0.4 Cluster

    NASA Astrophysics Data System (ADS)

    Yagi, Masafumi; Gu, Liyi; Koyama, Yusei; Nakata, Fumiaki; Kodama, Tadayuki; Hattori, Takashi; Yoshida, Michitoshi

    2015-02-01

    From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (\\lt 2.3 arcmin ˜ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst galaxies, all of which are spectroscopically confirmed members of the cluster. Four out of the nine parent galaxies show distortion of stellar distribution in the disk, which can be a sign of recent interaction, and the interaction may have made the EIGs. On the other hand, six parent galaxies (one overlaps those exhibiting distortion) show Hα emission without stars, which implies ram pressure stripping. The spectrum of the brightest parent galaxy shows a post-starburst signature and resembles the Hα stripped galaxies found in the Coma cluster. Meanwhile, two brightest parent galaxies in A851 are more massive than the EIG parent galaxies in the Coma cluster. This is consistent with a “downsizing” of star-forming galaxies, though it is still within the statistical variance. We also analyzed Suprime-Cam data of another z=0.39 cluster, CL0024+17, but found no EIGs. The key difference between A851 and CL0024+17 would be the existence of a subcluster colliding with the main body of A851, in which six or seven out of the nine parent galaxies in A851 exist, and the fraction of EIGs in the subcluster is significantly higher than the main subcluster of A851 and CL0024+17.

  4. Hα and [SII] emission from warm Ionized GAS in the Scutum-Centaurus Arm

    SciTech Connect

    Hill, Alex S.; Benjamin, Robert A.; Gostisha, Martin C.; Haffner, L. Matthew; Barger, Kathleen A.

    2014-06-01

    We present Wisconsin H-Alpha Mapper [SII] λ6716 and Hα spectroscopic maps of the warm ionized medium (WIM) in the Scutum-Centaurus Arm at Galactic longitudes 310° < l < 345°. Using extinction-corrected Hα intensities (I{sub Hα}{sup c}), we measure an exponential scale height of electron density squared in the arm of H{sub n{sub e{sup 2}}}=0.30 kpc (assuming a distance of 3.5 kpc), intermediate between that observed in the inner Galaxy and in the Perseus Arm. The [S II]/Hα line ratio is enhanced at large |z| and in sightlines with faint I{sub Hα}{sup c}. We find that the [S II]/Hα line ratio has a power-law relationship with I{sub Hα}{sup c} from a value of ≈1.0 at I{sub Hα}{sup c}<0.2 R (Rayleighs) to a value of ≈0.08 at I{sub Hα}{sup c}≳100 R. The line ratio is better correlated with Hα intensity than with height above the plane, indicating that the physical conditions within the WIM vary systematically with electron density. We argue that the variation of the line ratio with height is a consequence of the decrease of electron density with height. Our results reinforce the well-established picture in which the diffuse Hα emission is due primarily to emission from in situ photoionized gas, with scattered light only a minor contributor.

  5. Tracing kinematic (mis)alignments in CALIFA merging galaxies. Stellar and ionized gas kinematic orientations at every merger stage

    NASA Astrophysics Data System (ADS)

    Barrera-Ballesteros, J. K.; García-Lorenzo, B.; Falcón-Barroso, J.; van de Ven, G.; Lyubenova, M.; Wild, V.; Méndez-Abreu, J.; Sánchez, S. F.; Marquez, I.; Masegosa, J.; Monreal-Ibero, A.; Ziegler, B.; del Olmo, A.; Verdes-Montenegro, L.; García-Benito, R.; Husemann, B.; Mast, D.; Kehrig, C.; Iglesias-Paramo, J.; Marino, R. A.; Aguerri, J. A. L.; Walcher, C. J.; Vílchez, J. M.; Bomans, D. J.; Cortijo-Ferrero, C.; González Delgado, R. M.; Bland-Hawthorn, J.; McIntosh, D. H.; Bekeraitė, S.

    2015-10-01

    We present spatially resolved stellar and/or ionized gas kinematic properties for a sample of 103 interacting galaxies, tracing all merger stages: close companions, pairs with morphological signatures of interaction, and coalesced merger remnants. In order to distinguish kinematic properties caused by a merger event from those driven by internal processes, we compare our galaxies with a control sample of 80 non-interacting galaxies. We measure for both the stellar and the ionized gas components the major (projected) kinematic position angles (PAkin, approaching and receding) directly from the velocity distributions with no assumptions on the internal motions. This method also allow us to derive the deviations of the kinematic PAs from a straight line (δPAkin). We find that around half of the interacting objects show morpho-kinematic PA misalignments that cannot be found in the control sample. In particular, we observe those misalignments in galaxies with morphological signatures of interaction. On the other hand, thelevel of alignment between the approaching and receding sides for both samples is similar, with most of the galaxies displaying small misalignments. Radial deviations of the kinematic PA orientation from a straight line in the stellar component measured by δPAkin are large for both samples. However, for a large fraction of interacting galaxies the ionized gas δPAkin is larger than the typical values derived from isolated galaxies (48%), indicating that this parameter is a good indicator to trace the impact of interaction and mergers in the internal motions of galaxies. By comparing the stellar and ionized gas kinematic PA, we find that 42% (28/66) of the interacting galaxies have misalignments larger than 16°, compared to 10% from the control sample. Our results show the impact of interactions in the motion of stellar and ionized gas as well as the wide the variety of their spatially resolved kinematic distributions. This study also provides a local

  6. TIME-VARYING FLAME IONIZATION SENSING APPLIED TO NATURAL GAS AND PROPANE BLENDS IN A PRESSURIZED LEAN PREMIXED (LPM) COMBUSTOR

    SciTech Connect

    D. L. Straub; B. T. Chorpening; E. D. Huckaby; J. D. Thornton; W. L. Fincham

    2008-06-13

    In-situ monitoring of combustion phenomena is a critical need for optimal operation and control of advanced gas turbine combustion systems. The concept described in this paper is based on naturally occurring flame ionization processes that accompany the combustion of hydrocarbon fuels. Previous work has shown that flame ionization techniques may be applied to detect flashback, lean blowout, and some aspects of thermo-acoustic combustion instabilities. Previous work has focused on application of DC electric fields. By application of time-varying electric fields, significant improvements to sensor capabilities have been observed. These data have been collected in a lean premixed combustion test rig operating at 0.51-0.76 MPa (5-7.5 atm) with air preheated to 588 K (600°F). Five percent of the total fuel flow is injected through the centerbody tip as a diffusion pilot. The fuel composition is varied independently by blending approximately 5% (volume) propane with the pipeline natural gas. The reference velocity through the premixing annulus is kept constant for all conditions at a nominal value of 70 m/s. The fuel-air equivalence ratio is varied independently from 0.46 – 0.58. Relative to the DC field version, the time-varying combustion control and diagnostic sensor (TV-CCADS) shows a significant improvement in the correlation between the measured flame ionization current and local fuel-air equivalence ratio. In testing with different fuel compositions, the triangle wave data show the most distinct change in flame ionization current in response to an increase in propane content. Continued development of this sensor technology will improve the capability to control advanced gas turbine combustion systems, and help address issues associated with variations in fuel supplies.

  7. Highly ionized gas absorption in the disk and halo toward HD 167756 at 3.5 kilometers per second resolution

    NASA Technical Reports Server (NTRS)

    Savage, Blair D.; Sembach, Kenneth R.; Cardelli, Jason A.

    1994-01-01

    High-resolution spectra of interstellar Si IV, C IV, and N V absorption lines along the 4 kpc path to the inner Galaxy star HD 167756 at z = -0.85 kpc are presented. The spectra were obtained with the echelle mode of Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) and have signal-to-noise ratios ranging from 23 to 38. The high resolution of the measurements full width at half maximum (FWHM = 3.5 km/s) results in fully resolved line profiles for the highly ionized gas absorption. The measurements provide information on the column density per unit velocity, N(v), as a function of velocity for Si IV, C IV, and N V. The C IV and N V profiles extend from -70 to +70 km/s, while the Si IV profiles extend from -40 to +70 km/s. The integrated logarithmic column densities are long N(Si IV) = 13.09 +/- 0.02, log N(C IV) = 13.83 +/- 0.02, and log N(N V) = 13.56 +/- 0.03. The N V profile is broad, asymmetric, and featureless, while the Si IV profile contains narrow absorption components near V(sub LSR) = -19, 0, +20, and +52 km/s with Doppler spread parameters, b about = 10-12 km/s. The C IV profile contains both broad and narrow structure. The high ion feature near +52 km/s is also detected in the low-ionization lines of Ca II, O I, Si II, and Fe II. The other narrow Si IV and C IV components occur within several km/s of components seen in low-ionization species. The sight line contains at least two types of highly ionized gas. One type gives rise to a broad N V profile, and the other results in the more structured Si IV profile. The C IV profile contains contributions from both types of highly ionized gas. The broad but asymmetric N V profile is well represented by a large Galactic scale height gas which is participating in Galactic rotation and has a combination of thermal and turbulent broadening with b(sub tot) about = 42 km/s. The C IV to N V abundance ratio of 1.0 +/- 0.3 for the gas implies T about 1.6 x 10(exp 5) K or about 8 x 10

  8. Detection and Mapping of Decoupled Stellar and Ionized Gas Structures in the Ultraluminous Infrared Galaxy IRAS 12112+0305.

    PubMed

    Colina; Arribas; Borne; Monreal

    2000-04-10

    Integral field optical spectroscopy with the INTEGRAL fiber-fed system and Hubble Space Telescope optical imaging are used to map the complex stellar and warm ionized gas structure in the ultraluminous infrared galaxy IRAS 12112+0305. Images reconstructed from wavelength-delimited extractions of the integral field spectra reveal that the observed ionized gas distribution is decoupled from the stellar main body of the galaxy, with the dominant continuum and emission-line regions separated by projected distances of up to 7.5 kpc. The two optical nuclei are detected as apparently faint emission-line regions, and their optical properties are consistent with being dust-enshrouded weak [O i] LINERs. The brightest emission-line region is associated with a faint (mI=20.4), giant H ii region of 600 pc diameter, in which a young ( approximately 5 Myr) massive cluster of about 2x107 M middle dot in circle dominates the ionization. Internal reddening toward the line-emitting regions and the optical nuclei ranges from 1 to 8 mag in the visual. Taking the reddening into account, the overall star formation in IRAS 12112+0305 is dominated by starbursts associated with the two nuclei and corresponds to a star formation rate of 80 M middle dot in circle yr-1. PMID:10727379

  9. PRESENT-DAY GALACTIC EVOLUTION: LOW-METALLICITY, WARM, IONIZED GAS INFLOW ASSOCIATED WITH HIGH-VELOCITY CLOUD COMPLEX A

    SciTech Connect

    Barger, K. A.; Haffner, L. M.; Wakker, B. P.; Hill, Alex S.; Madsen, G. J.; Duncan, A. K. E-mail: haffner@astro.wisc.edu E-mail: wakker@astro.wisc.edu

    2012-12-20

    The high-velocity cloud Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin H{alpha} Mapper kinematically resolved observations of Complex A over the velocity range of -250 to -50 km s{sup -1} in the local standard of rest reference frame. These observations include the first full H{alpha} intensity map of Complex A across (l, b) = (124 Degree-Sign , 18 Degree-Sign ) to (171 Degree-Sign , 53 Degree-Sign ) and deep targeted observations in H{alpha}, [S II] {lambda}6716, [N II] {lambda}6584, and [O I] {lambda}6300 toward regions with high H I column densities, background quasars, and stars. The H{alpha} data imply that the masses of neutral and ionized material in the cloud are similar, both being greater than 10{sup 6} M{sub Sun }. We find that the Bland-Hawthorn and Maloney model for the intensity of the ionizing radiation near the Milky Way is consistent with the known distance of the high-latitude part of Complex A and an assumed cloud geometry that puts the lower-latitude parts of the cloud at a distance of 7-8 kpc. This compatibility implies a 5% ionizing photon escape fraction from the Galactic disk. We also provide the nitrogen and sulfur upper abundance solutions for a series of temperatures, metallicities, and cloud configurations for purely photoionized gas; these solutions are consistent with the sub-solar abundances found by previous studies, especially for temperatures above 10{sup 4} K or for gas with a high fraction of singly ionized nitrogen and sulfur.

  10. Present-day Galactic Evolution: Low-metallicity, Warm, Ionized Gas Inflow Associated with High-velocity Cloud Complex A

    NASA Astrophysics Data System (ADS)

    Barger, K. A.; Haffner, L. M.; Wakker, B. P.; Hill, Alex. S.; Madsen, G. J.; Duncan, A. K.

    2012-12-01

    The high-velocity cloud Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin Hα Mapper kinematically resolved observations of Complex A over the velocity range of -250 to -50 km s-1 in the local standard of rest reference frame. These observations include the first full Hα intensity map of Complex A across (\\mathit {l, b}) = (124{^\\circ }, 18{^\\circ }) to (171°, 53°) and deep targeted observations in Hα, [S II] λ6716, [N II] λ6584, and [O I] λ6300 toward regions with high H I column densities, background quasars, and stars. The Hα data imply that the masses of neutral and ionized material in the cloud are similar, both being greater than 106 M ⊙. We find that the Bland-Hawthorn & Maloney model for the intensity of the ionizing radiation near the Milky Way is consistent with the known distance of the high-latitude part of Complex A and an assumed cloud geometry that puts the lower-latitude parts of the cloud at a distance of 7-8 kpc. This compatibility implies a 5% ionizing photon escape fraction from the Galactic disk. We also provide the nitrogen and sulfur upper abundance solutions for a series of temperatures, metallicities, and cloud configurations for purely photoionized gas; these solutions are consistent with the sub-solar abundances found by previous studies, especially for temperatures above 104 K or for gas with a high fraction of singly ionized nitrogen and sulfur.

  11. P-MaNGA Galaxies: emission-lines properties - gas ionization and chemical abundances from prototype observations

    NASA Astrophysics Data System (ADS)

    Belfiore, F.; Maiolino, R.; Bundy, K.; Thomas, D.; Maraston, C.; Wilkinson, D.; Sánchez, S. F.; Bershady, M.; Blanc, G. A.; Bothwell, M.; Cales, S. L.; Coccato, L.; Drory, N.; Emsellem, E.; Fu, H.; Gelfand, J.; Law, D.; Masters, K.; Parejko, J.; Tremonti, C.; Wake, D.; Weijmans, A.; Yan, R.; Xiao, T.; Zhang, K.; Zheng, T.; Bizyaev, D.; Kinemuchi, K.; Oravetz, D.; Simmons, A.

    2015-05-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr Sloan Digital Sky Survey (SDSS-IV) survey that will obtain spatially resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we present the analysis of nebular emission-line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams, we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, which illustrates that galaxy characterizations based on single fibre spectra are necessarily incomplete. We observe extended low ionization nuclear emission-line regions (LINER)-like emission (up to 1Re) in the central regions of three galaxies. We make use of the Hα equivalent width [EW(Hα)] to argue that the observed emission is consistent with ionization from hot evolved stars. We derive stellar population indices and demonstrate a clear correlation between Dn(4000) and EW(HδA) and the position in the ionization diagnostic diagram: resolved galactic regions which are ionized by a Seyfert/LINER-like radiation field are also devoid of recent star formation and host older and/or more metal-rich stellar populations. We also detect extraplanar LINER-like emission in two highly inclined galaxies, and identify it with diffuse ionized gas. We investigate spatially resolved metallicities and find a positive correlation between metallicity and star formation rate surface density. We further study the relation between N/O versus O/H on resolved scales. We find that, at given N/O, regions within individual galaxies are spread towards lower metallicities, deviating from the sequence defined by galactic central regions as traced by Sloan 3-arcsec fibre spectra. We suggest that the observed dispersion can be a tracer for gas flows in galaxies: infalls of pristine gas and/or the effect of a galactic fountain.

  12. Quantitative and fingerprinting analysis of Atractylodes rhizome based on gas chromatography with flame ionization detection combined with chemometrics.

    PubMed

    Liu, Qiutao; Kong, Dandan; Luo, Jiaoyang; Kong, Weijun; Guo, Weiying; Yang, Meihua

    2016-07-01

    This study assessed the feasibility of gas chromatography with flame ionization detection fingerprinting combined with chemometrics for quality analysis of Atractylodes rhizome. We extracted essential oils from 20 Atractylodes lancea and Atractylodes koreana samples by hydrodistillation. The variation in extraction yields (1.33-4.06%) suggested that contents of the essential oils differed between species. The volatile components (atractylon, atractydin, and atractylenolide I, II, and III) were quantified by gas chromatography with flame ionization detection and confirmed by gas chromatography with mass spectrometry, and the results demonstrated that the number and content of volatile components differed between A. lancea and A. koreana. We then calculated the relative peak areas of common components and similarities of samples by comparing the chromatograms of A. lancea and A. koreana extracts. Also, we employed several chemometric techniques, including similarity analysis, hierarchical clustering analysis, principal component analysis, and partial least-squares discriminate analysis, to analyze the samples. Results were consistent across analytical methods and showed that samples could be separated according to species. Five volatile components in the essential oils were quantified to further validate the results of the multivariate statistical analysis. The method is simple, stable, accurate, and reproducible. Our results provide a foundation for quality control analysis of A. lancea and A. koreana.

  13. Quantitative and fingerprinting analysis of Atractylodes rhizome based on gas chromatography with flame ionization detection combined with chemometrics.

    PubMed

    Liu, Qiutao; Kong, Dandan; Luo, Jiaoyang; Kong, Weijun; Guo, Weiying; Yang, Meihua

    2016-07-01

    This study assessed the feasibility of gas chromatography with flame ionization detection fingerprinting combined with chemometrics for quality analysis of Atractylodes rhizome. We extracted essential oils from 20 Atractylodes lancea and Atractylodes koreana samples by hydrodistillation. The variation in extraction yields (1.33-4.06%) suggested that contents of the essential oils differed between species. The volatile components (atractylon, atractydin, and atractylenolide I, II, and III) were quantified by gas chromatography with flame ionization detection and confirmed by gas chromatography with mass spectrometry, and the results demonstrated that the number and content of volatile components differed between A. lancea and A. koreana. We then calculated the relative peak areas of common components and similarities of samples by comparing the chromatograms of A. lancea and A. koreana extracts. Also, we employed several chemometric techniques, including similarity analysis, hierarchical clustering analysis, principal component analysis, and partial least-squares discriminate analysis, to analyze the samples. Results were consistent across analytical methods and showed that samples could be separated according to species. Five volatile components in the essential oils were quantified to further validate the results of the multivariate statistical analysis. The method is simple, stable, accurate, and reproducible. Our results provide a foundation for quality control analysis of A. lancea and A. koreana. PMID:27133960

  14. The Ionized Gas and Nuclear Environment in NGC 3783. V. Variability and Modeling of the Intrinsic Ultraviolet Absorption

    NASA Astrophysics Data System (ADS)

    Gabel, Jack R.; Kraemer, Steven B.; Crenshaw, D. Michael; George, Ian M.; Brandt, W. N.; Hamann, Frederick W.; Kaiser, Mary Elizabeth; Kaspi, Shai; Kriss, Gerard A.; Mathur, Smita; Nandra, Kirpal; Netzer, Hagai; Peterson, Bradley M.; Shields, Joseph C.; Turner, T. J.; Zheng, Wei

    2005-10-01

    absorbers (components 1b, 2, and 3 with logU~-0.5) are consistent with the modeling results for the lowest ionization X-ray component, but with smaller total column density. The high-ionization UV components are found to have pressures similar to those of the three X-ray ionization components. These results are consistent with an inhomogeneous wind model for the outflow in NGC 3783, with denser, colder, lower ionization regions embedded in more highly ionized gas. (6) Based on the predicted emission-line luminosities, global covering factor constraints, and distances derived for the UV absorbers, they may be identified with emission-line gas observed in the inner NLR of AGNs. We explore constraints for dynamical models of AGN outflows implied by these results. Based on observations made with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555, and with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer, which is operated for NASA by Johns Hopkins University under NASA contract NAS5-32985.

  15. Fuel cell with ionization membrane

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2007-01-01

    A fuel cell is disclosed comprising an ionization membrane having at least one area through which gas is passed, and which ionizes the gas passing therethrough, and a cathode for receiving the ions generated by the ionization membrane. The ionization membrane may include one or more openings in the membrane with electrodes that are located closer than a mean free path of molecules within the gas to be ionized. Methods of manufacture are also provided.

  16. The ionized gas in the central region of NGC 5253. 2D mapping of the physical and chemical properties

    NASA Astrophysics Data System (ADS)

    Monreal-Ibero, A.; Walsh, J. R.; Vílchez, J. M.

    2012-08-01

    Context. Blue compact dwarf (BCD) galaxies constitute the ideal laboratories to test the interplay between massive star formation and the surrounding gas. As one of the nearest BCD galaxies, NGC 5253 was previously studied with the aim to elucidate in detail the starburst interaction processes. Some open issues regarding the properties of its ionized gas still remain to be addressed. Aims: The 2D structure of the main physical and chemical properties of the ionized gas in the core of NGC 5253 has been studied. Methods: Optical integral field spectroscopy (IFS) data has been obtained with FLAMES Argus and lower resolution gratings of the Giraffe spectrograph. Results: We derived 2D maps for different tracers of electron density (ne), electron temperature (Te) and ionization degree. The maps for ne as traced by [O ii], [S ii], [Fe iii], and [Ar iv] line ratios are compatible with a 3D stratified view of the nebula with the highest ne in the innermost layers and a decrease of ne outwards. 2D maps of Te were measured from [O iii] and [S ii] line ratios; to our knowledge, this is the first time that a Te map based on [S ii] lines for an extragalactic object has been presented. The joint interpretation of the Te([S ii]) and Te([O iii]) maps is consistent with a Te structure in 3D with higher temperatures close to the main ionizing source surrounded by a colder and more diffuse component. The highest ionization degree is found at the peak of emission for the gas with relatively high ionization in the main Giant H ii Region and lower ionization degree delineating the more extended diffuse component. We derived abundances of oxygen, neon, argon, and nitrogen. Abundances for O, Ne and Ar are constant over the mapped area within ≲0.1 dex. The mean 12 + log (O/H) is 8.26 ± 0.04 while the relative abundances of log (N/O), log (Ne/O) and log (Ar/O) were ~-1.32 ± 0.05, -0.65 ± 0.03 and -2.33 ± 0.06, respectively. There are two locations with enhanced N/O. The first (log (N

  17. The Residual Gas Ionization Profile Monitor in the J-PARC 3-GeV Rapid Cycling Synchrotron

    NASA Astrophysics Data System (ADS)

    Harada, Hiroyuki; Kato, Shinichi

    The residual gas Ionization Profile Monitor (IPM) is developed in the J-PARC 3-GeV RCS. The IPM is a non-destructive beam profile monitor to observe a circulating transverse beam profile in the ring. It is very important to observe the beam profile turn-by-turn in the ring for identification of the beam loss and emittance growth source because beam loss is always issue in increasing the beam power in terms of keeping hands on maintenance. The IPM has been continuously upgraded since 2008. The recent progress of the IPM is reported together with the outline of IPM system.

  18. Restoration of RI-beams from a projectile fragment separator by Laser Ionization gas Catcher-PALIS-

    SciTech Connect

    Sonoda, T.; Takamine, A.; Schury, P.; Yamazaki, Y.; Wada, M.; Okada, K.; Yoshida, A.; Kubo, T.; Matsuo, Y.; Furukawa, T.; Wakui, T.; Shinozuka, T.; Iimura, H.; Katayama, I.; Ohtani, S.; Wollnik, H.; Schuessler, H. A.; Kudryavtsev, Yu.; Van Duppen, P.; Huyse, M.

    2009-03-17

    A fragment separator at heavy ion accelerator facilities is a versatile instrument to provide wide variety of radioactive isotope (RI) beams. However, more than 99.99% of precious RI-ions are simply dumped in the slits or elsewhere in the fragment separator. A novel concept to restore such RI-ions for parasitic slow RI-beams is proposed. Installation of a laser ionization gas catcher in the vicinity of the first or second focal point of the fragment separator enables to collect dead isotopes in the slits. The design concept and expected performance are discussed.

  19. Ionization chamber

    DOEpatents

    Walenta, Albert H.

    1981-01-01

    An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.

  20. Ionization chamber

    DOEpatents

    Walenta, A.H.

    An ionization chamber is described which has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionizes the gas.

  1. Effect of Electrospray Ionization Source Conditions on the Tautomer Distribution of Deprotonated p-Hydroxybenzoic Acid in the Gas Phase.

    PubMed

    Xia, Hanxue; Attygalle, Athula B

    2016-06-01

    The deprotonation site of p-hydroxybenzoic acid upon electrospray ionization has been a subject of fervent debate in several articles in the Journal of the American Chemical Society and elsewhere. General consensus is that electrospray ionization mass spectrometry (ESI-MS) experimental results reflect the situation in solution to a considerable extent. Our research, using ion-mobility mass spectrometry, challenges the notion that ESI-MS results directly reflect solution-phase structures and demonstrates that the relative populations of the thermodynamically less favored gaseous carboxylate tautomer or the thermodynamically more favored gaseous phenoxide tautomer, generated from the same aqueous solution of p-hydroxybenzoic acid by ESI, can be varied back and forth by changing the probe position, capillary voltage, desolvation-gas temperature, sample infusion flow rate, and cone voltage. In other words, solvent effects are not the primary criteria that determine the relative population distributions of tautomeric carboxylate (C(-)) and phenoxide (P(-)) ions (m/z 137) generated by electrospray ionization of p-hydroxybenzoic acid. In addition, we propose that the observed ratio of the P(-) and C(-) forms indirectly reflects the relative contribution of the charge-residue or ion-evaporation process that occurs during the electrospray ion generation process.

  2. Determination of nitrosamines in water by gas chromatography/chemical ionization/selective ion trapping mass spectrometry.

    PubMed

    Pozzi, Romina; Bocchini, Paola; Pinelli, Francesca; Galletti, Guido C

    2011-04-01

    A gas chromatography/mass spectrometry (GC/MS) method for determination of nine N-nitrosamines (NAs) in water is described. Two ionization modes, electron impact (EI) and chemical ionization (CI) with methanol, as well as different ion analysis techniques, i.e. full scan, selected ion storage (SIS) and tandem mass spectrometry (MS/MS) were tested. Chemical ionization followed by SIS resulted the mass spectrometric method of choice, with detection limits in the range of 1-2ng/L. Solid Phase Extraction (SPE) with coconut charcoal cartridges was applied to extract NAs from real samples, according EPA Method 521. Drinking water samples were collected from seven surface- and two groundwater treatment plants. Three surface water treatment plants were sampled before and after addition of O(3)/ClO(2) to observe the effect of disinfection on NAs' formation. N-nitrosodiethylamine (NDEA), n-nitrosodipropylamine (NDPA), n-nitrosomorpholine (NMOR) and n-nitrosodibutylamine (NDBA) were found up to concentrations exceeding three times the risk level of 10ng/L set by the California Department of Public Health. Because dermal adsorption has been recently indicated as a new contamination route of exposure to NAs for people who practice swimming activity, water samples from five swimming pools in the Bologna (Italy) area were collected. N-nitrosopyrrolidine (NPYR) was detected in all samples at concentrations larger than 50ng/L, likely as a disinfection by-product from the amino acid precursor proline, a main constituent of skin collagen.

  3. Effect of Electrospray Ionization Source Conditions on the Tautomer Distribution of Deprotonated p-Hydroxybenzoic Acid in the Gas Phase.

    PubMed

    Xia, Hanxue; Attygalle, Athula B

    2016-06-01

    The deprotonation site of p-hydroxybenzoic acid upon electrospray ionization has been a subject of fervent debate in several articles in the Journal of the American Chemical Society and elsewhere. General consensus is that electrospray ionization mass spectrometry (ESI-MS) experimental results reflect the situation in solution to a considerable extent. Our research, using ion-mobility mass spectrometry, challenges the notion that ESI-MS results directly reflect solution-phase structures and demonstrates that the relative populations of the thermodynamically less favored gaseous carboxylate tautomer or the thermodynamically more favored gaseous phenoxide tautomer, generated from the same aqueous solution of p-hydroxybenzoic acid by ESI, can be varied back and forth by changing the probe position, capillary voltage, desolvation-gas temperature, sample infusion flow rate, and cone voltage. In other words, solvent effects are not the primary criteria that determine the relative population distributions of tautomeric carboxylate (C(-)) and phenoxide (P(-)) ions (m/z 137) generated by electrospray ionization of p-hydroxybenzoic acid. In addition, we propose that the observed ratio of the P(-) and C(-) forms indirectly reflects the relative contribution of the charge-residue or ion-evaporation process that occurs during the electrospray ion generation process. PMID:27164186

  4. Comparison of gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry with electron ionization and negative-ion chemical ionization for analyses of pesticides at trace levels in atmospheric samples.

    PubMed

    Raina, Renata; Hall, Patricia

    2008-09-09

    A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (OPs) and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin). The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg microL(-1) (<100 pg m(-3) in air). No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5-10 pg microL(-1)) along with best confirmation (<25% RSD of ion ratio), while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion). GC-EI/SRM at concentration <100 pg microL(-1) was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1-10 pg microL(-1)) for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT).

  5. Potential of gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry for screening and quantification of hexabromocyclododecane.

    PubMed

    Sales, Carlos; Portolés, Tania; Sancho, Juan Vicente; Abad, Esteban; Ábalos, Manuela; Sauló, Jordi; Fiedler, Heidelore; Gómara, Belén; Beltrán, Joaquim

    2016-01-01

    A fast method for the screening and quantification of hexabromocyclododecane (sum of all isomers) by gas chromatography using a triple quadrupole mass spectrometer with atmospheric pressure chemical ionization (GC-APCI-QqQ) is proposed. This novel procedure makes use of the soft atmospheric pressure chemical ionization source, which results in less fragmentation of the analyte than by conventional electron impact (EI) and chemical ionization (CI) sources, favoring the formation of the [M - Br](+) ion and, thus, enhancing sensitivity and selectivity. Detection was based on the consecutive loses of HBr from the [M - Br](+) ion to form the specific [M - H5Br6](+) and [M - H4Br5](+) ions, which were selected as quantitation (Q) and qualification (q) transitions, respectively. Parameters affecting ionization and MS/MS detection were studied. Method performance was also evaluated; calibration curves were found linear from 1 pg/μL to 100 pg/μL for the total HBCD concentration; instrumental detection limit was estimated to be 0.10 pg/μL; repeatability and reproducibility, expressed as relative standard deviation, were better than 7% in both cases. The application to different real samples [polyurethane foam disks (PUFs), food, and marine samples] pointed out a rapid way to identify and allow quantification of this compound together with a number of polybrominated diphenyl ethers (BDE congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two other novel brominated flame retardants [i.e., decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE)] because of their presence in the same fraction when performing the usual sample treatment.

  6. Potential of gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry for screening and quantification of hexabromocyclododecane.

    PubMed

    Sales, Carlos; Portolés, Tania; Sancho, Juan Vicente; Abad, Esteban; Ábalos, Manuela; Sauló, Jordi; Fiedler, Heidelore; Gómara, Belén; Beltrán, Joaquim

    2016-01-01

    A fast method for the screening and quantification of hexabromocyclododecane (sum of all isomers) by gas chromatography using a triple quadrupole mass spectrometer with atmospheric pressure chemical ionization (GC-APCI-QqQ) is proposed. This novel procedure makes use of the soft atmospheric pressure chemical ionization source, which results in less fragmentation of the analyte than by conventional electron impact (EI) and chemical ionization (CI) sources, favoring the formation of the [M - Br](+) ion and, thus, enhancing sensitivity and selectivity. Detection was based on the consecutive loses of HBr from the [M - Br](+) ion to form the specific [M - H5Br6](+) and [M - H4Br5](+) ions, which were selected as quantitation (Q) and qualification (q) transitions, respectively. Parameters affecting ionization and MS/MS detection were studied. Method performance was also evaluated; calibration curves were found linear from 1 pg/μL to 100 pg/μL for the total HBCD concentration; instrumental detection limit was estimated to be 0.10 pg/μL; repeatability and reproducibility, expressed as relative standard deviation, were better than 7% in both cases. The application to different real samples [polyurethane foam disks (PUFs), food, and marine samples] pointed out a rapid way to identify and allow quantification of this compound together with a number of polybrominated diphenyl ethers (BDE congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two other novel brominated flame retardants [i.e., decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE)] because of their presence in the same fraction when performing the usual sample treatment. PMID:26554601

  7. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ellis, Wade C.; Lewis, Charlotte R.; Openshaw, Anna P.; Farnsworth, Paul B.

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration.

  8. The Effects of Added Hydrogen on Noble Gas Discharges Used as Ambient Desorption/Ionization Sources for Mass Spectrometry.

    PubMed

    Ellis, Wade C; Lewis, Charlotte R; Openshaw, Anna P; Farnsworth, Paul B

    2016-09-01

    We demonstrate the effectiveness of using hydrogen-doped argon as the support gas for the dielectric barrier discharge (DBD) ambient desorption/ionization (ADI) source in mass spectrometry. Also, we explore the chemistry responsible for the signal enhancement observed when using both hydrogen-doped argon and hydrogen-doped helium. The hydrogen-doped argon was tested for five analytes representing different classes of molecules. Addition of hydrogen to the argon plasma gas enhanced signals for gas-phase analytes and for analytes coated onto glass slides in positive and negative ion mode. The enhancements ranged from factors of 4 to 5 for gas-phase analytes and factors of 2 to 40 for coated slides. There was no significant increase in the background. The limit of detection for caffeine was lowered by a factor of 79 using H2/Ar and 2 using H2/He. Results are shown that help explain the fundamental differences between the pure-gas discharges and those that are hydrogen-doped for both argon and helium. Experiments with different discharge geometries and grounding schemes indicate that observed signal enhancements are strongly dependent on discharge configuration. Graphical Abstract ᅟ. PMID:27380389

  9. Quantitative determination of terbutaline and orciprenaline in human plasma by gas chromatography/negative ion chemical ionization/mass spectrometry.

    PubMed

    Leis, H J; Gleispach, H; Nitsche, V; Malle, E

    1990-06-01

    A method for the determination of unconjugated terbutaline and orciprenaline in human plasma is described. The assay is based on stable isotope dilution gas chromatography/negative ion chemical ionization/mass spectrometry. An inexpensive and rapid method for preparation of stable isotope labelled analogues as well as their use in quantitative gas chromatography/mass spectrometry is shown. A highly efficient sample work-up procedure with product recoveries of more than 95% is presented. The method developed permits quantitative measurement of terbutaline and orciprenaline in human plasma down to 100 pg ml-1, using 1 ml of sample. Plasma levels of terbutaline after oral administration of 5 mg of terbutaline sulphate were estimated. PMID:2357489

  10. Metal-ligand redox reactions in gas-phase quaternary peptide-metal complexes by electrospray ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Vaisar, T.; Gatlin, C. L.; Turecek, F.

    1997-03-01

    The dipeptides Phe-Leu, Leu-Phe, Leu-Ala, and Ala-Leu form quaternary complexes of the type [Cu(II)(peptide - 2H+M)bpy]+ in the gas phase when electrosprayed in the presence of Cu(II) salts, 2.2'-bipyridyl (bpy), and an alkali hydroxide (MOH). The gas-phase complexes decarboxylate on collisional activation at low ion kinetic energies. The resulting ions undergo unusual eliminations of neutral Na, K, and Rb, which depend on the peptide structure. The ionization energy of the decarboxylated Phe-Leu-Cu-bpy complex was bracketed at 4.2 eV. Other collision-induced dissociations also depend on the alkali metal ion and the peptide structure. Ab initio calculations on a model system are reported and used to discuss the electronic properties of the peptide complexes.

  11. H ii REGION G46.5-0.2: THE INTERPLAY BETWEEN IONIZING RADIATION, MOLECULAR GAS, AND STAR FORMATION

    SciTech Connect

    Paron, S.; Ortega, M. E.; Dubner, G.; Petriella, A.; Giacani, E.; Yuan, Jing-Hua; Li, Jin Zeng; Liu, Hongli; Huang, Ya Fang; Zhang, Si-Ju; Wu, Yuefang

    2015-06-15

    H ii regions are particularly interesting because they can generate dense layers of gas and dust, elongated columns or pillars of gas pointing toward the ionizing sources, and cometary globules of dense gas where triggered star formation can occur. Understanding the interplay between the ionizing radiation and the dense surrounding gas is very important to explain the origin of these peculiar structures, and hence to characterize triggered star formation. G46.5-0.2 (G46), a poorly studied galactic H ii region located at about 4 kpc, is an excellent target for performing this kind of study. Using public molecular data extracted from the Galactic Ring Survey ({sup 13}CO J = 1–0) and from the James Clerk Maxwell Telescope data archive ({sup 12}CO, {sup 13}CO, C{sup 18}O J = 3–2, HCO{sup +}, and HCN J = 4–3), and infrared data from the GLIMPSE and MIPSGAL surveys, we perform a complete study of G46, its molecular environment, and the young stellar objects (YSOs) placed around it. We found that G46, probably excited by an O7V star, is located close to the edge of the GRSMC G046.34-00.21 molecular cloud. It presents a horse-shoe morphology opening in the direction of the cloud. We observed a filamentary structure in the molecular gas likely related to G46 and not considerable molecular emission toward its open border. We found that about 10′ to the southwest of G46 there are some pillar-like features, shining at 8 μm and pointing toward the H ii region open border. We propose that the pillar-like features were carved and sculpted by the ionizing flux from G46. We found several YSOs likely embedded in the molecular cloud grouped in two main concentrations: one, closer to the G46 open border consisting of Class II type sources, and another mostly composed of Class I type YSOs located just ahead of the pillar-like features, strongly suggesting an age gradient in the YSO distribution.

  12. H II Region G46.5-0.2: The Interplay between Ionizing Radiation, Molecular Gas, and Star Formation

    NASA Astrophysics Data System (ADS)

    Paron, S.; Ortega, M. E.; Dubner, G.; Yuan, Jing-Hua; Petriella, A.; Giacani, E.; Li, Jin Zeng; Wu, Yuefang; Liu, Hongli; Huang, Ya Fang; Zhang, Si-Ju

    2015-06-01

    H ii regions are particularly interesting because they can generate dense layers of gas and dust, elongated columns or pillars of gas pointing toward the ionizing sources, and cometary globules of dense gas where triggered star formation can occur. Understanding the interplay between the ionizing radiation and the dense surrounding gas is very important to explain the origin of these peculiar structures, and hence to characterize triggered star formation. G46.5-0.2 (G46), a poorly studied galactic H ii region located at about 4 kpc, is an excellent target for performing this kind of study. Using public molecular data extracted from the Galactic Ring Survey (13CO J = 1-0) and from the James Clerk Maxwell Telescope data archive (12CO, 13CO, C18O J = 3-2, HCO+, and HCN J = 4-3), and infrared data from the GLIMPSE and MIPSGAL surveys, we perform a complete study of G46, its molecular environment, and the young stellar objects (YSOs) placed around it. We found that G46, probably excited by an O7V star, is located close to the edge of the GRSMC G046.34-00.21 molecular cloud. It presents a horse-shoe morphology opening in the direction of the cloud. We observed a filamentary structure in the molecular gas likely related to G46 and not considerable molecular emission toward its open border. We found that about 10‧ to the southwest of G46 there are some pillar-like features, shining at 8 μm and pointing toward the H ii region open border. We propose that the pillar-like features were carved and sculpted by the ionizing flux from G46. We found several YSOs likely embedded in the molecular cloud grouped in two main concentrations: one, closer to the G46 open border consisting of Class II type sources, and another mostly composed of Class I type YSOs located just ahead of the pillar-like features, strongly suggesting an age gradient in the YSO distribution.

  13. The Ionized Gas and Nuclear Environment in NGC 3783. IV; Variability and Modeling of the 900 ks CHANDRA Spectrum

    NASA Technical Reports Server (NTRS)

    Netzer, Hagai; Kaspi, Shai; Behar, Ehud; Brandt, W. N.; Chelouche, Doron; George, Ian M.; Crenshaw, D. Michael; Gabel, Jack R.; Hamann, Frederick W.; George, Steven B.

    2003-01-01

    We present a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 (Kaspi et al. 2002). We split the data in various ways to look for time dependent and luminosity dependent spectral variations. This analysis, the measured equivalent widths of a large number of X-ray lines, and our photoionization calculations, lead us to the following conclusions: 1) NGC 3783 fluctuated in luminosity, by a factor N 1.5, during individual 170 ks observations. The fluctuations were not associated with significant spectral variations. 2) On a longer time scale, of 20-120 days, we discovered two very different spectral shapes that are noted the high state and the low state spectra. The observed changes between the two can be described as the appearance and disappearance of a soft continuum component. The spectral variations are not related, in a simple way, to the brightening or the fading of the short wavelength continuum, as observed in other objects. NGC3783 seems to be the first AGN to show this unusual behavior. 3) The appearance of the soft continuum component is consistent with beeing the only spectral variation and there is no need to invoke changes in the absorber s opacity. In particular, all absorption lines with reliable measurements show the same equivalent width, within the observational uncertainties, during high and low states. 4) Photoionization model calculations show that a combination of three ionization components, each split into two kinematic components, explain very well the intensity of almost all absorption lines and the bound-free absorption. The components span a large range of ionization and a total column of about 3 x 10(exp 22) per square centimeter Moreover, all components are thermally stable and are situated on the vertical branch of the stability curve.. This means that they are in pressure equilibrium and perhaps occupy the same volume of space. This is the first detection of such a multi-component equilibrium gas in

  14. Highly ionized gas in the Gum nebula and elsewhere - A comparison of IUE and Copernicus satellite results

    NASA Technical Reports Server (NTRS)

    Edgar, Richard J.; Savage, Blair D.

    1992-01-01

    The data from six high-dispersion IUE echelle spectra are averaged in order to obtain an interstellar absorption line spectrum with an S/N of about 30 and a resolution of about 25 km/s. The interstellar lines of C IV and Si IV are very strong and broad and N V is detected. The profiles for these species and Al III are compared to the Copernicus satellite profiles for O VI. The high ionization lines toward HD 64760 are much stronger and broader than those recorded toward Zeta Pup and Gamma super 2 Vel, the two exciting stars of the Gum nebula. The profiles for Al III and Si IV are similar and considerably narrower than the O VI profile. An origin in photoionized Gum nebula gas is suggested as the most likely explanation for Al III and Si IV. The C IV profile has a high positive velocity wing extending to approximately +80 km/s, which is similar in appearance to the positive velocity portion of the O VI profile. It is inferred that a substantial part of the observed C IV has an origin in the collisionally ionized gas most likely rsponsible for the O VI.

  15. A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

    NASA Astrophysics Data System (ADS)

    Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

    2016-10-01

    A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

  16. Gas Chromatography Coupled to Atmospheric Pressure Chemical Ionization FT-ICR Mass Spectrometry for Improvement of Data Reliability.

    PubMed

    Schwemer, Theo; Rüger, Christopher P; Sklorz, Martin; Zimmermann, Ralf

    2015-12-15

    Atmospheric pressure chemical ionization (APCI) offers the advantage of molecular ion information with low fragmentation. Hyphenating APCI to gas chromatography (GC) and ultrahigh resolution mass spectrometry (FT-ICR MS) enables an improved characterization of complex mixtures. Data amounts acquired by this system are very huge, and existing peak picking algorithms are usually extremely time-consuming, if both gas chromatographic and ultrahigh resolution mass spectrometric data are concerned. Therefore, automatic routines are developed that are capable of handling these data sets and further allow the identification and removal of known ionization artifacts (e.g., water- and oxygen-adducts, demethylation, dehydrogenation, and decarboxylation). Furthermore, the data quality is enhanced by the prediction of an estimated retention index, which is calculated simply from exact mass data combined with a double bond equivalent correction. This retention index is used to identify mismatched elemental compositions. The approach was successfully tested for analysis of semivolatile components in heavy fuel oil and diesel fuel as well as primary combustion particles emitted by a ship diesel research engine. As a result, 10-28% of the detected compounds, mainly low abundant species, classically assigned by using only the mass spectrometric information, were identified as not valid and removed. Although GC separation is limited by the slow acquisition rate of the FT-ICR MS (<1 Hz), a database driven retention time comparison, as commonly used for low resolution GC/MS, can be applied for revealing isomeric information.

  17. Narrowband HST images of M87: Evidence for a disk of ionized gas around a massive black hole

    NASA Technical Reports Server (NTRS)

    Ford, Holland C.; Harms, Richard J.; Tsvetanov, Zlatan I.; Hartig, George F.; Dressel, Linda L.; Kriss, Gerard A.; Bohlin, Ralph C.; Davidsen, Arthur F.; Margon, Bruce; Kochhar, Ajay K.

    1994-01-01

    We present Hubble Space Telescope Wide Field/Planetary Camera-2 (HST WFPC2) narrowband H-alpha + (N II) images of M87 which show a small disk of ionized gas with apparent spiral structure surrounding the nucleus of M87. The jet projects approximately 19.5 deg from the minor axis of the disk, which suggests that the jet is approximately normal to the disk. In a companion Letter, Harms et al. measure the radial velocities at r = +/- 0.25 sec along a line perpendicular to the jet, showing that one side of the disk is approaching at 500 +/- 50 km/s and the other side of the disk is receding at 500 +/- 50 km/s. Absorption associated with the disk and the sense of rotation imply that the apparent spiral arms trail the rotation. The observed radial velocites corrected for a 42 deg inclination of the disk imply rotation at +/- 750 km/s. Analysis of velocity measurements at four positions near the nucleus gives a total mass of approximately 2.4 +/- 0.7 x 10(exp 9) solar mass within 18 pc of the nucleus, and a mass-to-light ratio (M/L)(sub I) = 170. We conclude that there is a disk of ionized gas feeding a massive black hole in the center of M87.

  18. Gas Chromatography Coupled to Atmospheric Pressure Chemical Ionization FT-ICR Mass Spectrometry for Improvement of Data Reliability.

    PubMed

    Schwemer, Theo; Rüger, Christopher P; Sklorz, Martin; Zimmermann, Ralf

    2015-12-15

    Atmospheric pressure chemical ionization (APCI) offers the advantage of molecular ion information with low fragmentation. Hyphenating APCI to gas chromatography (GC) and ultrahigh resolution mass spectrometry (FT-ICR MS) enables an improved characterization of complex mixtures. Data amounts acquired by this system are very huge, and existing peak picking algorithms are usually extremely time-consuming, if both gas chromatographic and ultrahigh resolution mass spectrometric data are concerned. Therefore, automatic routines are developed that are capable of handling these data sets and further allow the identification and removal of known ionization artifacts (e.g., water- and oxygen-adducts, demethylation, dehydrogenation, and decarboxylation). Furthermore, the data quality is enhanced by the prediction of an estimated retention index, which is calculated simply from exact mass data combined with a double bond equivalent correction. This retention index is used to identify mismatched elemental compositions. The approach was successfully tested for analysis of semivolatile components in heavy fuel oil and diesel fuel as well as primary combustion particles emitted by a ship diesel research engine. As a result, 10-28% of the detected compounds, mainly low abundant species, classically assigned by using only the mass spectrometric information, were identified as not valid and removed. Although GC separation is limited by the slow acquisition rate of the FT-ICR MS (<1 Hz), a database driven retention time comparison, as commonly used for low resolution GC/MS, can be applied for revealing isomeric information. PMID:26560682

  19. Nature of the ionizing source of the nuclear gas in NGC 1052

    SciTech Connect

    Keel, W.C.; Miller, J.S.

    1983-03-15

    We examine the ionization and physical state of the emission-line region in the nucleus of elliptical galaxy NGC 1052. The (O III) lambda4363/lambda5007 ratio, frequently used as a diagnostic for ionization mechanisms, is very poorly determined because of difficulties in matching the underlying stellar continuum spectrum, which is unusual in having very strong lines for the galaxy luminosity. Within these limitations, we find the (O III) temperature to be only marginally compatible with shock models, and the overall emission spectrum to be better fitted by photoionization models with a very dilute flat-spectrum central source. In any event, the case for NGC 1052 as a shock-heated nucleus is not strong.

  20. THE KINEMATICS AND IONIZATION OF NUCLEAR GAS CLOUDS IN CENTAURUS A

    SciTech Connect

    Bicknell, Geoffrey V.; Sutherland, Ralph S.; Neumayer, Nadine E-mail: Ralph.Sutherland@anu.edu.au

    2013-03-20

    Neumayer et al. established the existence of a blueshifted cloud in the core of Centaurus A, within a few parsecs of the nucleus and close to the radio jet. We propose that the cloud has been impacted by the jet, and that it is in the foreground of the jet, accounting for its blueshifted emission on the southern side of the nucleus. We consider both shock excitation and photoionization models for the excitation of the cloud. Shock models do not account for the [Si VI] and [Ca VIII] emission line fluxes. However, X-ray observations indicate a source of ionizing photons in the core of Centaurus A; photoionization by the inferred flux incident on the cloud can account for the fluxes in these lines relative to Brackett-{gamma}. The power-law slope of the ionizing continuum matches that inferred from synchrotron models of the X-rays. The logarithm of the ionization parameter is -1.9, typical of that in Seyfert galaxies and consistent with the value proposed for dusty ionized plasmas. The model cloud density depends upon the Lorentz factor of the blazar and the inclination of our line of sight to the jet axis. For acute inclinations, the inferred density is consistent with expected cloud densities. However, for moderate inclinations of the jet to the line of sight, high Lorentz factors imply cloud densities in excess of 10{sup 5} cm{sup -3} and very low filling factors, suggesting that models of the gamma-ray emission should incorporate jet Lorentz factors {approx}< 5.

  1. Measurement of neutral gas pressure in the D-module of GAMMA 10/PDX by using ASDEX type fast ionization gauge

    NASA Astrophysics Data System (ADS)

    Ichimura, K.; Fukumoto, M.; Islam, M. M.; Islam, M. S.; Shimizu, K.; Fukui, K.; Ohuchi, M.; Nojiri, K.; Terakado, A.; Yoshikawa, M.; Ezumi, N.; Sakamoto, M.; Nakashima, Y.

    2016-11-01

    In the divertor simulation experiments in the GAMMA 10/PDX tandem mirror, pressure of the neutral gas was investigated by using a fast ionization gauge. The gauge was absolutely calibrated for hydrogen gas by using a capacitance manometer. Change of the gauge sensitivity due to the magnetic field of GAMMA 10/PDX was also evaluated. The typical gas pressure measured in detached plasma experiments was 0.1-10 Pa. The degree of plasma detachment determined from the reduction of heat flux was enhanced as the gas pressure increases. Rapid increase of the gas pressure under the plasma flow was also observed.

  2. Observation of increased space-charge limited thermionic electron emission current by neutral gas ionization in a weakly-ionized deuterium plasma

    SciTech Connect

    Hollmann, E. M.; Yu, J. H.; Doerner, R. P.; Nishijima, D.; Seraydarian, R. P.

    2015-09-14

    The thermionic electron emission current emitted from a laser-produced hot spot on a tungsten target in weakly-ionized deuterium plasma is measured. It is found to be one to two orders of magnitude larger than expected for bipolar space charge limited thermionic emission current assuming an unperturbed background plasma. This difference is attributed to the plasma being modified by ionization of background neutrals by the emitted electrons. This result indicates that the allowable level of emitted thermionic electron current can be significantly enhanced in weakly-ionized plasmas due to the presence of large neutral densities.

  3. A Desorbed Gas Molecular Ionization Mechanism for Arcing Onset in Solar Arrays Immersed in a Low-Density Plasma

    NASA Technical Reports Server (NTRS)

    Galofaro, J.; Vayner, B.; Ferguson, D.; Degroot, W.

    2002-01-01

    Previous experimental studies have hypothesized that the onset of Solar Array Arc (SAA) initiation in low-density space plasmas is caused by a desorbed gas molecular ionization mechanism. Indeed past investigations performed at the NASA Glenn Plasma Interaction Facility tend to not only support the desorbed gas molecular ionization mechanism, but have gone as far as identifying the crucial molecular species that must be present for molecular ion dominated process to occur. When electrical breakdown occurs at a triple junction site on a solar array panel, a quasi-neutral plasma cloud is ejected. Assuming the main component of the expelled plasma cloud by weight is due to water vapor, the fastest process available is due to HO molecules and OH(+) ions, or more succinctly, dissociative molecular-ion dominated recombination processes: H2O(+) + e(-) yields H* + OH*. Recently published spectroscopic observations of solar array arc spectra in ground tests have revealed the well-known molecular OH band (302 to 309nm), as well as the molecular SiH band (387nm peak), and the molecular CH band (432nm peak). Note that the OH band is observed in emission arcs where water vapor is present. Strong atomic lines were also observed for H(sub beta) at 486nm and H(sub alpha) at 656.3nm in prior ground testing. Independent supporting evidence of desorbed gas molecular ionization mechanisms also come from measurements of arc current pulse widths at different capacitances. We will revisit an earlier first order approximation demonstrating the dependence of arc current pulse widths on the square root of the capacitance. The simple arc current pulse width model will be then be used to estimate the temperature of the arc plasma (currently believed to be somewhere in the range of 3 to 5 eV). The current paper then seeks to extend the outlined work by including numerous vacuum chamber measurements obtained with a quadrupole mass spectrometer. A small solar array was mounted inside the vacuum

  4. Broad spectrum drug screening using electron-ionization gas chromatography-mass spectrometry (EI-GCMS).

    PubMed

    Stone, Judy

    2010-01-01

    A liquid-liquid extraction (LLE) of drugs and internal standard (promazine) is performed by mixing urine at basic pH with 1-chlorobutane. There are no hydrolysis or derivatization steps. After centrifugation the organic (upper) layer is transferred to another tube and evaporated. The dried extract is reconstituted with ethyl acetate and 1 microL is injected onto the GCMS. Drugs are volatilized in the GC inlet and separated on a capillary column. In the EI source drugs become positively charged and fragment. Mass analysis of ionized fragments occurs with a single quadrupole. The resulting full scan mass spectra are automatically searched against three libraries. PMID:20077071

  5. Acceleration of electrons generated during ionization of a gas by a nearly flat profile laser pulse

    SciTech Connect

    Singh, Kunwar Pal

    2009-09-15

    A scheme of acceleration of electrons generated during ionization of krypton by nearly flat radial and nearly flat temporal laser pulse profiles has been suggested. The energy spectrum of the electrons suggests that energy of the electrons is higher for a nearly flat temporal profile than that for a nearly flat radial profile. The suppression of scattering of the electrons is better for a nearly flat radial profile than that for a nearly flat temporal profile. The energy of the electrons increases, scattering decreases, and beam quality improves with an increase in flatness of radial and temporal profiles.

  6. Determination of nitrosamines in water by gas chromatography/chemical ionization/selective ion trapping mass spectrometry.

    PubMed

    Pozzi, Romina; Bocchini, Paola; Pinelli, Francesca; Galletti, Guido C

    2011-04-01

    A gas chromatography/mass spectrometry (GC/MS) method for determination of nine N-nitrosamines (NAs) in water is described. Two ionization modes, electron impact (EI) and chemical ionization (CI) with methanol, as well as different ion analysis techniques, i.e. full scan, selected ion storage (SIS) and tandem mass spectrometry (MS/MS) were tested. Chemical ionization followed by SIS resulted the mass spectrometric method of choice, with detection limits in the range of 1-2ng/L. Solid Phase Extraction (SPE) with coconut charcoal cartridges was applied to extract NAs from real samples, according EPA Method 521. Drinking water samples were collected from seven surface- and two groundwater treatment plants. Three surface water treatment plants were sampled before and after addition of O(3)/ClO(2) to observe the effect of disinfection on NAs' formation. N-nitrosodiethylamine (NDEA), n-nitrosodipropylamine (NDPA), n-nitrosomorpholine (NMOR) and n-nitrosodibutylamine (NDBA) were found up to concentrations exceeding three times the risk level of 10ng/L set by the California Department of Public Health. Because dermal adsorption has been recently indicated as a new contamination route of exposure to NAs for people who practice swimming activity, water samples from five swimming pools in the Bologna (Italy) area were collected. N-nitrosopyrrolidine (NPYR) was detected in all samples at concentrations larger than 50ng/L, likely as a disinfection by-product from the amino acid precursor proline, a main constituent of skin collagen. PMID:21377686

  7. A practical gas chromatography flame ionization detection method for the determination of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane in silicone emulsions.

    PubMed

    Brothers, Herbert M; Bovens, Eric; Bruni, Antonio; Habitz, Tanya M; Hamachi, Tadashi; Han, Yuanhua; Ji, Zhouhua; Kerbleski, Joel J; Letouche, Claude; Lu, Yi Dong; Nguyen, Regis; Rivard, Michelle L; Qi, Xiaoman; Shoji, Miki; Tanaka, Ken; Tecklenburg, Ronald E

    2016-04-01

    A gas chromatography with flame ionization detection (GC-FID) method for analysis of D4, D5, and D6 cyclic siloxanes in silicone emulsions is described. Sample preparation involves breaking the emulsion with methanol and hexanes, and then analyzing the hexanes phase after derivatization with hexamethyldisilazane (HMDS). Silylation is performed to reduce the potential for formation of cyclic siloxanes during the course of the GC analysis. The accuracy of the method was verified by performing analyses on samples spiked with known levels of D4, D5 and D6 and by comparison to a referee method using atmospheric pressure chemical ionization liquid chromatography with mass spectrometry detection (APCI-LC-MS). Absolute differences of the results obtained between the two techniques were 0.03 weight percent or less, and relative differences were 15% or less. The reproducibility and ruggedness of the method was demonstrated by performing a global round robin test at four different geographic sites on four different types of silicone emulsions. The %RSDs obtained were less than 10% for all analytes and all emulsions examined. PMID:26968230

  8. A VUV photoionization measurement and ab-initio calculation of the ionization energy of gas phase SiO2

    SciTech Connect

    Kostko, Oleg; Ahmed, Musahid; Metz, Ricardo B.

    2008-12-05

    In this work we report on the detection and vacuum-ultraviolet (VUV) photoionization of gas phase SiO2 generated in situ via laser ablation of silicon in a CO2 molecular beam. The resulting species are investigated by single photon ionization with tunable VUV synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for SiO and SiO2 and ionization energy estimates are revealed from such measurements. A state-to-state ionizationenergy of 12.60 (+-0.05) eV is recorded by fitting two prominent peaks in the PIE curve for the following process: 1SUM O-Si-O --> 2PRODg [O-Si-O]+. Electronic structure calculations aid in the interpretation of the photoionization process and allow for identification of the symmetric stretch of 2PRODg [O-Si-O]+ which is observed in the PIE spectrum to be 0.11 eV (890 cm-1) above the ground state of the cation and agrees with the 892 cm-1 symmetric stretch frequency calculated at the CCSD(T)/aug-cc-pVTZ level.

  9. Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.

    PubMed

    Dai, Jiayu; Hou, Yong; Yuan, Jianmin

    2010-06-18

    Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

  10. Measurement of lysergic acid diethylamide (LSD) in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry.

    PubMed

    Papac, D I; Foltz, R L

    1990-01-01

    A previously reported procedure for quantification of LSD in urine was modified to permit measurement of the drug in plasma. After addition of deuterium-labelled LSD, the plasma is extracted and the extract is treated with trifluoroacetylimidazole to convert the LSD to its N-trifluoroacetyl derivative. The derivatized LSD is analyzed by capillary column gas chromatography/negative ion chemical ionization. Plasma fortified with known concentrations of LSD gave linear responses from 0.1 to 3.0 ng/mL with this assay. The method was used to determine pharmacokinetic parameters for LSD after oral administration (1 microgram/kg) to a male volunteer. The apparent plasma half-life was determined to be 5.1 h. The peak plasma concentration of 1.9 ng/mL occurred 3 h after administration.

  11. THE ORIGIN OF THE 6.4 keV LINE EMISSION AND H{sub 2} IONIZATION IN THE DIFFUSE MOLECULAR GAS OF THE GALACTIC CENTER REGION

    SciTech Connect

    Dogiel, V. A.; Chernyshov, D. O.; Tatischeff, V.; Terrier, R.

    2013-07-10

    We investigate the origin of the diffuse 6.4 keV line emission recently detected by Suzaku and the source of H{sub 2} ionization in the diffuse molecular gas of the Galactic center (GC) region. We show that Fe atoms and H{sub 2} molecules in the diffuse interstellar medium of the GC are not ionized by the same particles. The Fe atoms are most likely ionized by X-ray photons emitted by Sgr A* during a previous period of flaring activity of the supermassive black hole. The measured longitudinal intensity distribution of the diffuse 6.4 keV line emission is best explained if the past activity of Sgr A* lasted at least several hundred years and released a mean 2-100 keV luminosity {approx}> 10{sup 38} erg s{sup -1}. The H{sub 2} molecules of the diffuse gas cannot be ionized by photons from Sgr A*, because soft photons are strongly absorbed in the interstellar gas around the central black hole. The molecular hydrogen in the GC region is most likely ionized by low-energy cosmic rays, probably protons rather than electrons, whose contribution into the diffuse 6.4 keV line emission is negligible.

  12. Formation and Fragmentation of Protonated Molecules after Ionization of Amino Acid and Lactic Acid Clusters by Collision with Ions in the Gas Phase.

    PubMed

    Poully, Jean-Christophe; Vizcaino, Violaine; Schwob, Lucas; Delaunay, Rudy; Kocisek, Jaroslav; Eden, Samuel; Chesnel, Jean-Yves; Méry, Alain; Rangama, Jimmy; Adoui, Lamri; Huber, Bernd

    2015-08-01

    Collisions between O(3+) ions and neutral clusters of amino acids (alanine, valine and glycine) as well as lactic acid are performed in the gas phase, in order to investigate the effect of ionizing radiation on these biologically relevant molecular systems. All monomers and dimers are found to be predominantly protonated, and ab initio quantum-chemical calculations on model systems indicate that for amino acids, this is due to proton transfer within the clusters after ionization. For lactic acid, which has a lower proton affinity than amino acids, a significant non-negligible amount of the radical cation monomer is observed. New fragment-ion channels observed from clusters, as opposed to isolated molecules, are assigned to the statistical dissociation of protonated molecules formed upon ionization of the clusters. These new dissociation channels exhibit strong delayed fragmentation on the microsecond time scale, especially after multiple ionization.

  13. The Ionized Gas in Nearby Galaxies as Traced by the [N II] 122 and 205 μm Transitions

    NASA Astrophysics Data System (ADS)

    Herrera-Camus, R.; Bolatto, A.; Smith, J. D.; Draine, B.; Pellegrini, E.; Wolfire, M.; Croxall, K.; de Looze, I.; Calzetti, D.; Kennicutt, R.; Crocker, A.; Armus, L.; van der Werf, P.; Sandstrom, K.; Galametz, M.; Brandl, B.; Groves, B.; Rigopoulou, D.; Walter, F.; Leroy, A.; Boquien, M.; Tabatabaei, F. S.; Beirao, P.

    2016-08-01

    The [N ii] 122 and 205 μm transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ˜1 kpc, with observations of both [N ii] far-infrared lines. We measure [N ii] 122/205 line ratios in the ˜0.6-6 range, which corresponds to electron gas densities of n e ˜ 1-300 cm-3, with a median value of n e = 30 cm-3. Variations in the electron density within individual galaxies can be as high as a factor of ˜50, frequently with strong radial gradients. We find that n e increases as a function of infrared color, dust-weighted mean starlight intensity, and star-formation rate (SFR) surface density (ΣSFR). As the intensity of the [N ii] transitions is related to the ionizing photon flux, we investigate their reliability as tracers of the SFR. We derive relations between the [N ii] emission and SFR in the low-density limit and in the case of a log-normal distribution of densities. The scatter in the correlation between [N ii] surface brightness and ΣSFR can be understood as a property of the n e distribution. For regions with n e close to or higher than the [N ii] line critical densities, the low-density limit [N ii]-based SFR calibration systematically underestimates the SFR because the [N ii] emission is collisionally quenched. Finally, we investigate the relation between [N ii] emission, SFR, and n e by comparing our observations to predictions from the MAPPINGS-III code.

  14. Development and validation of a gas chromatography-flame ionization detection method for quantifying sucrose in equine serum.

    PubMed

    Hewetson, Michael; Aaltonen, Kaisa; Tulamo, Riitta-Mari; Sankari, Satu

    2014-03-01

    A simple and accurate method for quantifying sucrose in equine serum that can be applied to sucrose permeability testing in the horse was developed and validated using gas chromatography with flame ionization detection. The assay provided an acceptable degree of linearity, accuracy, and precision at concentrations of sucrose as low as 2.34 μmol/l and as high as 20.45 μmol/l. Percentage recovery of sucrose from serum ranged from 89% to 102%; repeatability and intermediate precision (relative standard deviation) ranged from 3.6% to 6.7% and 4.1% to 9.3%, respectively. The limit of detection was 0.73 μmol/l. No interfering peaks were observed except lactose, which gave 2 peaks, one of which overlapped partially with sucrose. To evaluate the suitability of the method for quantifying sucrose in serum samples from horses with naturally occurring gastric ulceration, 10 horses with and without naturally occurring gastric ulceration were subjected to sucrose permeability testing. All horses demonstrated an increase in serum sucrose concentration over time following oral administration of sucrose; however, the increase from baseline was significant for horses with gastric ulceration at 45 min (P = 0.0082) and 90 min (P = 0.0082) when compared with healthy horses. It was concluded that gas chromatography with flame ionization detection is a valid method for quantifying sucrose in equine serum and can be applied directly to the analysis of sucrose in equine serum as part of a larger validation study aimed at developing a blood test for the diagnosis of gastric ulcers in horses.

  15. Highly Ionized Gas in the Galactic Halo and the High Velocity Clouds Toward PG 1116+215

    NASA Astrophysics Data System (ADS)

    Ganguly, R.; Sembach, K. R.; Tripp, T. M.; Savage, B. D.

    2003-12-01

    Recent observations of extragalactic objects with FUSE have revealed the presence of high ionization OVI absorption associated with high velocity clouds (HVCs), defined as gas which lies at absolute velocities beyond 100 km/s in the Local Standard of Rest. We have acquired high spectral resolution observations with STIS ( ˜ 10 km/s) and FUSE ( ˜ 20 km/s) of the quasar PG 1116+215. The spectra show absorption at Vlsr=184km/s from a wide range of ionization species:CIV, OI, OVI, MgII, SiII, SiIII, SiIV, and FeII. The strong and broad O VI absorption in this HVC extends from ˜ 120 to 230 km/s with a weak wing of absorption to 300km/s. Although the HVC is not seen in HI 21 cm emission down to N(HI) ˜ 2x1018 cm-2, it is seen in the HI Lyman series up to at least the 918.13Å line. In addition, we have non-detection constraints on the column denisties of CI, NI, NV, and SII. We can rule out photoionization in an ultra-low density (n ˜ 10-6 cm-3) Local Group medium adopted by some investigators to explain the O VI and O VII absorption detected in several directions. We are currently in the process of determining if these data either support or rule out other models of HVCs, such as the Warm-Hot Intergalactic Medium, Dark Matter dominated mini-halos, or interactions with a low density (10-4-10-5 cm-3) Galactic corona or Local Group medium. In addition, we will also use abundance infomation to study the enrichment history and constrain possible sources for the high velocity gas, such as tidal debris from cannibalized galaxies.

  16. The Ionized Gas in Nearby Galaxies as Traced by the [N II] 122 and 205 μm Transitions

    NASA Astrophysics Data System (ADS)

    Herrera-Camus, R.; Bolatto, A.; Smith, J. D.; Draine, B.; Pellegrini, E.; Wolfire, M.; Croxall, K.; de Looze, I.; Calzetti, D.; Kennicutt, R.; Crocker, A.; Armus, L.; van der Werf, P.; Sandstrom, K.; Galametz, M.; Brandl, B.; Groves, B.; Rigopoulou, D.; Walter, F.; Leroy, A.; Boquien, M.; Tabatabaei, F. S.; Beirao, P.

    2016-08-01

    The [N ii] 122 and 205 μm transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ˜1 kpc, with observations of both [N ii] far-infrared lines. We measure [N ii] 122/205 line ratios in the ˜0.6–6 range, which corresponds to electron gas densities of n e ˜ 1–300 cm‑3, with a median value of n e = 30 cm‑3. Variations in the electron density within individual galaxies can be as high as a factor of ˜50, frequently with strong radial gradients. We find that n e increases as a function of infrared color, dust-weighted mean starlight intensity, and star-formation rate (SFR) surface density (ΣSFR). As the intensity of the [N ii] transitions is related to the ionizing photon flux, we investigate their reliability as tracers of the SFR. We derive relations between the [N ii] emission and SFR in the low-density limit and in the case of a log-normal distribution of densities. The scatter in the correlation between [N ii] surface brightness and ΣSFR can be understood as a property of the n e distribution. For regions with n e close to or higher than the [N ii] line critical densities, the low-density limit [N ii]-based SFR calibration systematically underestimates the SFR because the [N ii] emission is collisionally quenched. Finally, we investigate the relation between [N ii] emission, SFR, and n e by comparing our observations to predictions from the MAPPINGS-III code.

  17. Penning Ionization Electron Spectroscopy in Glow Discharge: A New Dimension for Gas Chromatography Detectors

    NASA Technical Reports Server (NTRS)

    Sheverev, V. A.; Khromov, N. A.; Kojiro, D. R.; Fonda, Mark (Technical Monitor)

    2002-01-01

    Admixtures to helium of 100 ppm and 5 ppm of nitrogen, and 100 ppm and 10 ppm of carbon monoxide were identified and measured in the helium discharge afterglow using an electrical probe placed into the plasma. For nitrogen and carbon monoxide gases, the measured electron energy spectra display distinct characteristic peaks (fingerprints). Location of the peaks on the energy scale is determined by the ionization energies of the analyte molecules. Nitrogen and carbon monoxide fingerprints were also observed in a binary mixture of these gases in helium, and the relative concentration analytes has been predicted. The technically simple and durable method is considered a good candidate for a number of analytical applications, and in particular, in GC and for analytical flight instrumentation.

  18. Study of solid/gas phase photocatalytic reactions by electron ionization mass spectrometry.

    PubMed

    Nuño, Manuel; Ball, Richard J; Bowen, Chris R

    2014-08-01

    This paper describes a novel methodology for the real-time study of solid-gas phase photocatalytic reactions in situ. A novel reaction chamber has been designed and developed to facilitate the investigation of photoactive materials under different gas compositions. UV irradiation in the wavelength of ranges 376-387 and 381-392 nm was provided using specially designed high efficiency light emitting diode arrays. The experiments used air containing 190 ppm NO2 in a moist environment with a relative humidity of 0.1%. Photocatalytic samples consisting of pressed pellets of rutile and anatase crystalline forms of TiO2 were monitored over a period of 150 min. An ultra-high vacuum right angled bleed valve allowed a controlled flow of gas from the main reaction chamber at atmospheric pressure to a residual gas analyser operating at a vacuum of 10(-5)  mbar. The apparatus and methodology have been demonstrated to provide high sensitivity (ppb). The rate of degradation of NO2 attributed to reaction at the TiO2 surface was sensitive to both crystal structures (anatase or rutile) and wavelength of irradiation.

  19. Nebular emission from AGN in the ultraviolet/optical: diagnostics of the ionizing source and gas properties

    NASA Astrophysics Data System (ADS)

    Feltre, A.

    2016-08-01

    Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, forthcoming facilities such as JWST and the E-ELT, will provide rest-frame ultraviolet and optical spectra of the very distant AGN. To lay the groundwork for the interpretation of these revolutionary datasets, we have recently computed new photoionization models of the narrow-line emitting regions (NLR) of AGN and combined them with similar models of the nebular emission from star-forming galaxies. In this talk, I will first describe how new ultraviolet and standard optical spectral diagnostics allow one to distinguish between nuclear activity and star formation. I will then explain how predictions of AGN nebular emission can be best used to understand the physical properties of the AGN NLR gas. In particular, I will present recent results from a study on one of the most comprehensive set of optical spectra (from VIMOS/VLT) sampling the rest-frame ultraviolet range of ~90 type 2 AGN (1.5 < z < 3), drawn from the z-COSMOS deep survey. To conclude, I will show how the implementation of AGN photoionization calculations in an innovative Bayesian fitting code can help us best interpret current, and future, spectro-photometric data on active galaxies.

  20. [Gas chromatography with a Pulsed discharge helium ionization detector for measurement of molecular hydrogen(H2) in the atmosphere].

    PubMed

    Luan, Tian; Fang, Shuang-xi; Zhou, Ling-xi; Wang, Hong-yang; Zhang, Gen

    2015-01-01

    A high precision GC system with a pulsed discharge helium ionization detector was set up based on the commercial Agilent 7890A gas chromatography. The gas is identified by retention time and the concentration is calculated through the peak height. Detection limit of the system is about 1 x 10(-9) (mole fraction, the same as below). The standard deviation of 140 continuous injections with a standard cylinder( concentration is roughly 600 x 10(-9)) is better than 0.3 x 10(-9). Between 409.30 x 10(-9) and 867.74 x 10(-9) molecular hydrogen mole fractions and peak height have good linear response. By using two standards to quantify the air sample, the precision meets the background molecular hydrogen compatibility goal within the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) program. Atmospheric molecular hydrogen concentration at Guangzhou urban area was preliminarily measured by this method from January to November 2013. The results show that the atmospheric molecular hydrogen mole fraction varies from 450 x 10(-9) to 700 x 10(-9) during the observation period, with the lowest value at 14:00 (Beijing time, the same as below) and the peak value at 20:00. The seasonal variation of atmospheric hydrogen at Guangzhou area was similar with that of the same latitude stations in northern hemisphere.

  1. On the origins of the diffuse Hα emission: ionized gas or dust-scattered Hα halos?

    NASA Astrophysics Data System (ADS)

    Seon, Kwang-Il; Witt, Adolf N.

    2015-03-01

    We find that the dust-scattering origin of the diffuse Hα emission cannot be ruled out. As opposed to the previous contention, the expected dust-scattered Hα halos surrounding H II regions are, in fact, in good agreement with the observed Hα morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stellar types, and clumpiness of the interstellar medium (ISM) and find that the observed line ratios of [S II]/Hα, [N II]/Hα, and He I λ5876/Hα in the diffuse ISM accord well with the dust-scattered halos around H II regions, which are photoionized by late O- and/or early B-type stars. We also demonstrate that the Hα absorption feature in the underlying continuum from the dust-scattered starlight (``diffuse galactic light'') and unresolved stars is able to substantially increase the [S II]/Hα and [N II]/Hα line ratios in the diffuse ISM.

  2. Gas chromatographic quantification of fatty acid methyl esters: flame ionization detection vs. electron impact mass spectrometry.

    PubMed

    Dodds, Eric D; McCoy, Mark R; Rea, Lorrie D; Kennish, John M

    2005-04-01

    The determination of FAME by GC is among the most commonplace analyses in lipid research. Quantification of FAME by GC with FID has been effectively performed for some time, whereas detection with MS has been used chiefly for qualitative analysis of FAME. Nonetheless, the sensitivity and selectivity of MS methods advocate a quantitative role for GC-MS in FAME analysis-an approach that would be particularly advantageous for FAME determination in complex biological samples, where spectrometric confirmation of analytes is advisable. To assess the utility of GC-MS methods for FAME quantification, a comparative study of GC-FID and GC-MS methods has been conducted. FAME in prepared solutions as well as a biological standard reference material were analyzed by GC-FID and GC-MS methods using both ion trap and quadrupole MS systems. Quantification by MS, based on total ion counts and processing of selected ions, was investigated for FAME ionized by electron impact. Instrument precision, detection limits, calibration behavior, and response factors were investigated for each approach, and quantitative results obtained by each technique were compared. Although there were a number of characteristic differences between the MS methods and FID with respect to FAME analysis, the quantitative performance of GC-MS compared satisfactorily with that of GC-FID. The capacity to combine spectrometric examination and quantitative determination advances GC-MS as a powerful alternative to GC-FID for FAME analysis. PMID:16028722

  3. [S IV] IN THE NGC 5253 SUPERNEBULA: IONIZED GAS KINEMATICS AT HIGH RESOLUTION

    SciTech Connect

    Beck, Sara C.; Lacy, John H.; Turner, Jean L.; Kruger, Andrew; Richter, Matt; Crosthwaite, Lucian P.

    2012-08-10

    The nearby dwarf starburst galaxy NGC 5253 hosts a deeply embedded radio-infrared supernebula excited by thousands of O stars. We have observed this source in the 10.5 {mu}m line of S{sup +3} at 3.8 km s{sup -1} spectral and 1.''4 spatial resolution, using the high-resolution spectrometer TEXES on the IRTF. The line profile cannot be fit well by a single Gaussian. The best simple fit describes the gas with two Gaussians, one near the galactic velocity with FWHM 33.6 km s{sup -1} and another of similar strength and FWHM 94 km s{sup -1} centered {approx}20 km s{sup -1} to the blue. This suggests a model for the supernebula in which gas flows toward us out of the molecular cloud, as in a 'blister' or 'champagne flow' or in the H II regions modelled by Zhu.

  4. Characterization of diacylglycerol isomers in edible oils using gas chromatography-ion trap electron ionization mass spectrometry.

    PubMed

    Zhu, Hanjiang; Clegg, Michael S; Shoemaker, Charles F; Wang, Selina C

    2013-08-23

    Verifying the authenticity of edible oils is of international concern. A new quality control standard for olive oil has been proposed that relates the ratio of 1,2-diacylglycerol (DAG) to 1,3-DAG to sensory aspects of olive oil. DAGs and their isomers are difficult to quantitate and characterize by Flame Ionization Gas Chromatography (GC-FID) due to the lack of suitable standards. Mass detectors offer the advantage of providing structural detail to the eluding DAG(s), thus removing ambiguity to the identification of both resolved and unresolved DAGs in GC chromatograms. In this study, a GC Electron Ionization Mass Spectrometry (GC-EI-MS) method was developed to determine the fatty acid composition and molecular structure of trimethylsilyl (TMS) derivatized DAGs present in edible oils. Twenty-two species of DAG isomers were identified in refined coconut oil and unrefined olive oil utilizing signature fragment ions, [M-15](+), [M-89](+), [M-RCO2](+), [RCO2+58](+) and [M-RCO2CH2](+). The [M-RCO2CH2](+) ion is considered the key diagnostic ion to distinguish between DAG positional isomers. MS/MS spectra of [M-RCO2](+) and [M-15](+) ions obtained from commercial standards containing both 1,2- and 1,3-DAG isomers were used as a model system to confirm the identification of DAG isomers in natural products. Furthermore, a number of reaction mechanisms are proposed to explain the formation of the most abundant mass fragments of DAGs and their isomers.

  5. Kinematics and Excitation of the Ram Pressure Stripped Ionized Gas Filaments in the Coma Cluster of Galaxies

    NASA Astrophysics Data System (ADS)

    Yoshida, Michitoshi; Yagi, Masafumi; Komiyama, Yutaka; Furusawa, Hisanori; Kashikawa, Nobunari; Hattori, Takashi; Okamura, Sadanori

    2012-04-01

    We present the results of deep imaging and spectroscopic observations of very extended ionized gas (EIG) around four member galaxies of the Coma Cluster of galaxies: RB 199, IC 4040, GMP 2923, and GMP 3071. The EIGs were serendipitously found in an Hα narrowband imaging survey of the central region of the Coma Cluster. The relative radial velocities of the EIGs with respect to the systemic velocities of the parent galaxies from which they emanate increase almost monotonically with the distance from the nucleus of the respective galaxies, reaching ~ - 400 to - 800 km s-1 at around 40-80 kpc from the galaxies. The one-sided morphologies and the velocity fields of the EIGs are consistent with the predictions of numerical simulations of ram pressure stripping. We found a very low velocity filament (v rel ~ -1300 km s-1) at the southeastern edge of the disk of IC 4040. Some bright compact knots in the EIGs of RB 199 and IC 4040 exhibit blue continuum and strong Hα emission. The equivalent widths of the Hα emission exceed 200 Å and are greater than 1000 Å for some knots. The emission-line intensity ratios of the knots are basically consistent with those of sub-solar abundance H II regions. These facts indicate that intensive star formation occurs in the knots. Some filaments, including the low-velocity filament of the IC 4040 EIG, exhibit shock-like emission-line spectra, suggesting that shock heating plays an important role in ionization and excitation of the EIGs. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  6. DENSITY OF WARM IONIZED GAS NEAR THE GALACTIC CENTER: LOW RADIO FREQUENCY OBSERVATIONS

    SciTech Connect

    Roy, Subhashis

    2013-08-10

    We have observed the Galactic center (GC) region at 0.154 and 0.255 GHz with the Giant Metrewave Radio Telescope. A total of 62 compact likely extragalactic (EG) sources are detected. Their scattering sizes decrease linearly with increasing angular distance from the GC up to about 1 Degree-Sign . The apparent scattering sizes of the sources are more than an order of magnitude less than predicted earlier by the NE2001 model of Galactic electron distribution within 359. Degree-Sign 5 < l < 0. Degree-Sign 5 and -0. Degree-Sign 5 < b < 0. Degree-Sign 5 (Hyperstrong Scattering Region) of the Galaxy. High free-free optical depths ({tau}) are observed toward most of the extended non-thermal sources within 0. Degree-Sign 6 from the GC. Significant variation of {tau} indicates that the absorbing medium is patchy at an angular scale of {approx}10' and n{sub e} is {approx}10 cm{sup -3}, which matches the NE2001 model. This model predicts the EG sources to be resolved out from 1.4 GHz interferometric surveys. However, out of 10 EG sources expected in the region, 8 likely EG are present in the 1.4 GHz catalog. Ionized interfaces of dense molecular clouds to the ambient medium are most likely responsible for strong scattering and low radio frequency absorption. However, dense GC clouds traced by CS J = 1-0 emission are found to have a narrow distribution of {approx}0. Degree-Sign 2 across the Galactic plane. Angular distribution of most EG sources seen through the so-called Hyperstrong Scattering Region are random in b, and typically {approx}7 out of 10 sources will not be seen through the dense molecular clouds, which explains why most of them are not scatter broadened at 1.4 GHz.

  7. Hubble Space Telescope/WFPC2 and VLA Observations of the Ionized Gas in the Dwarf Starburst Galaxy NGC 4214

    NASA Astrophysics Data System (ADS)

    MacKenty, John W.; Maíz-Apellániz, Jesús; Pickens, Christopher E.; Norman, Colin A.; Walborn, Nolan R.

    2000-12-01

    We present new Hα and [O III] λ5007 narrowband images of the starbursting dwarf galaxy NGC 4214, obtained with the Wide Field and Planetary Camera (WFPC2) on board the Hubble Space Telescope (HST), together with VLA observations of the same galaxy. The HST images resolve features down to physical scales of 2-5 pc, revealing several young (<10 Myr) star-forming complexes of various ionized gas morphologies (compact knots, complete or fragmentary shells) and sizes (~10-200 pc). Our results are consistent with a uniform set of evolutionary trends: The youngest, smaller, filled regions that presumably are those just emerging from dense star-forming clouds tend to be of high excitation and are highly obscured. Evolved, larger shell-like regions have lower excitation and are less extincted owing to the action of stellar winds and supernovae. In at least one case we find evidence for induced star formation, which has led to a two-stage starburst. Age estimates based on W(Hα) measurements do not agree with those inferred from wind-driven shell models of expanding H II regions. The most likely explanation for this effect is the existence of an ~2 Myr delay in the formation of superbubbles caused by the pressure exerted by the high-density medium in which massive stars are born. We report the detection of a supernova remnant embedded in one of the two large H II complexes of NGC 4214. The dust in NGC 4214 is not located in a foreground screen but is physically associated with the warm ionized gas. Based on observations with the NASA/ESA Hubble Space Telescope and the NRAO Very Large Array. The HST observations were obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  8. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    SciTech Connect

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  9. Highly-Ionized Gas in the Galactic Halo: A FUSE Survey of O 6 Absorption toward 22 Halo Stars

    NASA Astrophysics Data System (ADS)

    Zsargo, J.; Sembach, K. R.; Howk, J. C.; Savage, B. D.

    2002-12-01

    Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of 22 Galactic halo stars are studied to determine the amount of O 6 in the Galactic halo between ~0.3 and ~10 kpc from the Galactic mid-plane. Strong O 6 λ 1031.93 absorption was detected toward 21 stars, and a reliable 3 σ upper limit was obtained toward HD 97991. The weaker member of the O 6 doublet at 1037.62 Å could be studied toward only six stars. The observed columns are reasonably consistent with a patchy exponential O 6 distribution with a mid-plane density of 1.7x10-8 cm-3 and scale height between 2.3 and 4 kpc. We do not see clear signs of strong high-velocity components in O 6 absorption along the Galactic sight lines, which indicates the general absence of high velocity O 6 within 2-5 kpc of the Galactic mid-plane. The correlation between the H 1 and O 6 intermediate velocity absorption is also poor. The O 6 velocity dispersions are much larger than the value of ~18 km/s expected from thermal broadening for gas at T ~ 3x105 K, the temperature at which O 6 is expected to reach its peak abundance in collisional ionization equilibrium. Turbulence, inflow, and outflow must have an effect on the shape of the O 6 profiles. Kinematical comparisons of O 6 with Ar 1 reveal that 9 of 21 sight lines are closely aligned in LSR velocity (|Δ VLSR| <=5 km/s ), while 8 of 21 exhibit significant velocity differences (|Δ VLSR| >= 15 km/s ). This dual behavior may indicate the presence of two different types of O 6-bearing environments toward the Galactic sight lines. Comparison of O 6 with other highly-ionized species suggests that the high ions are produced primarily by cooling hot gas in the Galactic fountain flow, and that turbulent mixing also has a significant contribution. The role of turbulent mixing is most important toward sight lines that sample supernova remnants like Loop I and IV. We are also able to show that the O 6 enhancement toward the Galactic center region that was observed in the FUSE

  10. Gas and particulate phase products from the ozonolysis of acenaphthylene

    NASA Astrophysics Data System (ADS)

    Riva, Matthieu; Healy, Robert M.; Tomaz, Sophie; Flaud, Pierre-Marie; Perraudin, Emilie; Wenger, John C.; Villenave, Eric

    2016-10-01

    Polycyclic aromatic hydrocarbons (PAHs) are recognized as important secondary organic aerosol (SOA) precursors in the urban atmosphere. In this work, the gas-phase ozonolysis of acenaphthylene was investigated in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) for on-line characterization of the oxidation products in the gas and particle phases, respectively. SOA samples were also collected on filters and analyzed by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). The major gas-phase products included a range of oxygenated naphthalene derivatives such as 1,8-naphthalic anhydride, naphthalene 1,8-dicarbaldehyde and naphthaldehyde, as well as a secondary ozonide. Possible reaction mechanisms are proposed for the formation of these products and favoured pathways have been suggested. Many of these products were also found in the particle phase along with a range of oligomeric compounds. The same range of gas and particle phase products was observed in the presence and absence of excess cyclohexane, an OH scavenger, indicating that OH radical production from the ozonolysis of acenaphthylene is negligible. SOA yields in the range 23-37% were determined and indicate that acenaphthylene ozonolysis may contribute to part of the SOA observed in urban areas.

  11. Determination of linoleic acid in toothpaste by gas chromatography with flame ionization detection.

    PubMed

    Wejnerowska, Grazyna; Gackowska, Alicja; Gaca, Jerzy

    2008-06-01

    A new method for the determination of linoleic acid (LA) in toothpaste by a routine analysis has been proposed. Studies were based on the ISO 5509 procedure, which was modified for the purpose of LA determination in the toothpaste. Gas chromatography (GC) was employed for the qualitative and quantitative determination of linoleic acid methyl ester. The content of LA (5.31%) in sunflower oil added to the toothpaste composition (0.5%) was determined, and then the optimization studies for the determination of LA in the toothpaste samples were carried out. The relative standard deviation (RSD) of the procedure developed was 9.96% (n = 9). The quantitative analysis showed that the content of LA in the toothpaste samples studied was 0.0258 +/- 0.0011%. The detection limit of LA in toothpaste was approximately 0.001%.

  12. Electroscopy Ionization Photoelectron Spectroscopy: Probing the Electronic Structure of Inorganic Metal Complexes in the Gas Phase

    SciTech Connect

    Waters, Tom; Wang, Xue B.; Wang, Lai S.

    2007-02-01

    The coupling of electrospray to photoelectron spectroscopy has allowed a number of negatively charged solution phase transition metal complexes to be transferred to the gas phase and studied by photoelectron spectroscopy for the first time. Experiments have been performed on a range of species, including classic square-planar and octahedral transition-metal halide complexes, metal-metal bonded species, transition metal bis(dithiolene) centers and a variety of mononuclear and polynuclear iron-sulfur clusters that are related to important bioinorganic centers. The studies have provided detailed information about the electronic structure and molecular orbital energy levels of these species, allowing for direct comparison with theoretical calculations, and providing insight into their intrinsic redox properties in the absence of solvation.

  13. The temperature and ionization structure of the emitting gas in HII galaxies: implications for the accuracy of abundance determinations

    NASA Astrophysics Data System (ADS)

    Hägele, Guillermo F.; Pérez-Montero, Enrique; Díaz, Ángeles I.; Terlevich, Elena; Terlevich, Roberto

    2006-10-01

    We propose a methodology to perform a self-consistent analysis of the physical properties of the emitting gas of HII galaxies adequate to the data that can be obtained with the 21st century technology. This methodology requires the production and calibration of empirical relations between the different line temperatures that should supersede currently used ones based on very simple, and poorly tested, photoionization model sequences. As a first step to reach these goals, we have obtained simultaneous blue to far red long-slit spectra with the William Herschel Telescope (WHT) of three compact HII galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 2 (DR2) spectral catalogue using the INAOE Virtual Observatory superserver. Our spectra cover the range from 3200 to 10500Å, including the Balmer jump, the [OII]λλ3727, 29Å lines, the [SIII]λλ9069, 9532Å doublet as well as various weak auroral lines such as [OIII]λ4363Å and [SIII]λ6312Å. For the three objects, we have measured at least four line temperatures, T([OIII]), T([SIII]), T([OII]) and T([SII]), and the Balmer continuum temperature T(Bac). These measurements and a careful and realistic treatment of the observational errors yield total oxygen abundances with accuracies between 5 and 9 per cent. These accuracies are expected to improve as better calibrations based on more precise measurements, both on electron temperatures and densities, are produced. We have compared our obtained spectra with those downloaded from the SDSS DR3 finding a satisfactory agreement. The analysis of these spectra yields values of line temperatures and elemental ionic and total abundances which are in general agreement with those derived from the WHT spectra, although for most quantities they can only be taken as estimates since, due to the lack of direct measurements of the required lines, theoretical models had to be used whose uncertainties are impossible to quantify. The ionization structure found for the

  14. Warm ionized gas in CALIFA early-type galaxies. 2D emission-line patterns and kinematics for 32 galaxies

    NASA Astrophysics Data System (ADS)

    Gomes, J. M.; Papaderos, P.; Kehrig, C.; Vílchez, J. M.; Lehnert, M. D.; Sánchez, S. F.; Ziegler, B.; Breda, I.; Dos Reis, S. N.; Iglesias-Páramo, J.; Bland-Hawthorn, J.; Galbany, L.; Bomans, D. J.; Rosales-Ortega, F. F.; Cid Fernandes, R.; Walcher, C. J.; Falcón-Barroso, J.; García-Benito, R.; Márquez, I.; Del Olmo, A.; Masegosa, J.; Mollá, M.; Marino, R. A.; González Delgado, R. M.; López-Sánchez, Á. R.; Califa Collaboration

    2016-04-01

    Context. The morphological, spectroscopic, and kinematical properties of the warm interstellar medium (wim) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive, quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer an unprecedented opportunity for advancing our understanding of the wim in ETGs. Aims: This article centers on a 2D investigation of the wim component in 32 nearby (≲150 Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample. Methods: The analysis presented here includes Hα intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, and ionized-gas and stellar kinematics. It is supplemented by τ-ratio maps, which are a more efficient means to quantify the role of photoionization by the post-AGB stellar component than alternative mechanisms (e.g., AGN, low-level star formation). Results: Confirming and strengthening our previous conclusions, we find that ETGs span a broad continuous sequence in the properties of their wim, exemplified by two characteristic classes. The first (type i) comprises systems with a nearly constant EW(Hα) in their extranuclear component, which quantitatively agrees with (but is no proof of) the hypothesis that photoionization by the post-AGB stellar component is the main driver of extended wim emission. The second class (type ii) stands for virtually wim-evacuated ETGs with a very low (≤0.5 Å), outwardly increasing EW(Hα). These two classes appear indistinguishable from one another by their LINER-specific emission-line ratios in their extranuclear component. Here we extend the tentative classification we proposed previously by the type i+, which is assigned to a subset of type i ETGs exhibiting ongoing low-level star-forming activity in their periphery. This finding along with faint

  15. Three-dimensional modeling of ionized gas. II. Spectral energy distributions of massive and very massive stars in stationary and time-dependent modeling of the ionization of metals in H II regions

    NASA Astrophysics Data System (ADS)

    Weber, J. A.; Pauldrach, A. W. A.; Hoffmann, T. L.

    2015-11-01

    Context. H II regions play a crucial role in the measurement of the chemical composition of the interstellar medium and provide fundamental data about element abundances that constrain models of galactic chemical evolution. Discrepancies that still exist between observed emission line strengths and those predicted by nebular models can be partly attributed to the spectral energy distributions (SEDs) of the sources of ionizing radiation used in the models as well as to simplifying assumptions made in nebular modeling. Aims: One of the main influences on the nebular spectra is the metallicity, both nebular and stellar, which shows large variations even among nearby galaxies. Although nebular modeling often involves testing of different nebular metallicities against their influence on the predicted spectra, adequate grids of stellar atmospheres and realistic SEDs for different metallicities are still lacking. This is unfortunate because the influence of stellar metallicity on nebular line strength ratios, via its effect on the SEDs, is of similar importance as variations in the nebular metallicity. To overcome this deficiency we have computed a grid of model atmosphere SEDs for massive and very massive O-type stars covering a range of metallicities from significantly subsolar (0.1 Z⊙) to supersolar (2 Z⊙). Methods: The SEDs have been computed using a state-of-the-art model atmosphere code that takes into account the attenuation of the ionizing flux by the spectral lines of all important elements and the hydrodynamics of the radiatively driven winds and their influence on the SEDs. For the assessment of the SEDs in nebular simulations we have developed a (heretofore not available) 3D radiative transfer code that includes a time-dependent treatment of the metal ionization. Results: Using the SEDs in both 1D and 3D nebular models we explore the relative influence of stellar metallicity, gas metallicity, and inhomogeneity of the gas on the nebular ionization structure

  16. A new method for total OH reactivity measurements using a fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Sinha, V.; Bockisch, S.; Klüpfel, T.; Williams, J.

    2012-05-01

    The primary and most important oxidant in the atmosphere is the hydroxyl radical (OH). Currently OH sinks, particularly gas phase reactions, are poorly constrained. One way to characterize the overall sink of OH is to measure directly the ambient loss rate of OH, the total OH reactivity. To date direct measurements of total OH reactivity have been either performed using a Laser Induced Fluorescence (LIF) system ("pump-and-probe" or "flow reactor") or the Comparative Reactivity Method (CRM) with a Proton Transfer Reaction Mass Spectrometer (PTR-MS). Both techniques require large, complex and expensive detection systems. This study presents a feasibility assessment for CRM total OH reactivity measurements using a new detector, a Gas Chromatographic Photo-Ionization Detector (GC-PID). Such a system is smaller, more portable, less power consuming and less expensive than other total OH reactivity measurement techniques. Total OH reactivity is measured by the CRM using a competitive reaction between a reagent (here pyrrole) with OH alone and in the presence of atmospheric reactive molecules. The new CRM method for total OH reactivity has been tested with parallel measurements of the GC-PID and the previously validated PTR-MS as detector for the reagent pyrrole during laboratory experiments, plant chamber and boreal field studies. Excellent agreement of both detectors was found when the GC-PID was operated under optimum conditions. Time resolution (60-70 s), sensitivity (LOD 3-6 s-1) and overall uncertainty (25% in optimum conditions) for total OH reactivity were equivalent to PTR-MS based total OH reactivity measurements. One drawback of the GC-PID system was the steady loss of sensitivity and accuracy during intensive measurements lasting several weeks, and a possible toluene interference. Generally, the GC-PID system has been shown to produce closely comparable results to the PTR-MS and thus in suitable environments (e.g. forests) it presents a viably economical

  17. Gas-Phase Stability of G-quadruplex DNA Determined by Electrospray Ionization Tandem Mass Spectrometry and Molecular Dynamics Simulations

    PubMed Central

    Mazzitelli, Carolyn L.; Wang, Junmei; Smith, Suncerae I.; Brodbelt, Jennifer S.

    2007-01-01

    The relative gas-phase stabilities of seven quadruplex DNA structures, [d(TG4T)]4, [d(T2G3T)]4, [d(G4T4G4)]2, [d(T2AG3)2]2, d(T2AG3)4, d(T2G4)4, and d(G2T4)4, were investigated using molecular dynamics simulations and electrospray ionization mass spectrometry (ESI-MS). MD simulations revealed that the G-quadruplexes maintained their structures in the gas phase although the G-quartets were distorted to some degree and ammonium ions, retained by [d(TG4T)]4 and [d(T2G3T)]4, played a key role in stabilizing the tetrad structure. Energy-variable collisional activated dissociation was used to assess the relative stabilities of each quadruplex based on E1/2 values, and the resulting order of relative stabilities was found to be [d(TG4T)]4 ≫ d(T2AG3)4 ∼ d(T2G4)4 > [d(T2G3T)]4 > [d(T2AG3)2]2 ∼ d(G2T4)4 ∼ [d(G4T4G4)]2. The stabilities from the E1/2 values generally paralleled the RMSD and relative free energies of the quadruplexes based on the MD energy analysis. One exception to the general agreement is [d(G4T4G4)]2 which had the lowest E1/2 value, but was determined to be the most stable quadruplex according to the free energy analysis and ranked fourth based on the RMSD comparison. This discrepancy is attributed to differences in the fragmentation pathway of the quadruplex. PMID:17719795

  18. Time-of-flight ERD with a 200 mm2 Si3N4 window gas ionization chamber energy detector

    NASA Astrophysics Data System (ADS)

    Julin, Jaakko; Laitinen, Mikko; Sajavaara, Timo

    2014-08-01

    Low energy heavy ion elastic recoil detection work has been carried out in Jyväskylä since 2009 using home made timing detectors, a silicon energy detector and a timestamping data acquisition setup forming a time-of-flight-energy telescope. In order to improve the mass resolution of the setup a new energy detector was designed to replace the silicon solid state detector, which suffered from radiation damage and had poor resolution for heavy recoils. In this paper the construction and operation of an isobutane filled gas ionization chamber with a 14 × 14 mm2 100 nm thick silicon nitride window are described. In addition to greatly improved energy resolution for heavy ions, the detector is also able to detect hydrogen recoils simultaneously in the energy range of 100-1000 keV. Additionally the detector has position sensitivity by means of timing measurement, which can be performed without compromising the performance of the detector in any other way. The achieved position sensitivity improves the depth resolution near the surface.

  19. Determination of fluoride in toothpaste using headspace solid-phase microextraction and gas chromatography-flame ionization detection.

    PubMed

    Wejnerowska, Grazyna; Karczmarek, Anna; Gaca, Jerzy

    2007-05-25

    A new method for determination of fluoride in toothpaste employing the headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/flame ionization detection (GC/FID) has been proposed. It is a development of the method for determination of fluoride using trimethylchlorosilane (TMCS) as the derivatization reagent to form trimethylfluorosilane (TMFS), with the liquid/liquid extraction (LLE) step replaced by HS-SPME. To introduce the latter, it was necessary to determine the conditions of the reaction and to optimize the two stages of the SPME procedure: extraction and desorption. The parameters of the SPME analysis using carboxen/polydimethylsiloxane (CAR/PDMS) fiber were defined and compared with the corresponding ones for the LLE method, used as a reference. Also, these two methods were compared with respect to their linearity, precision, and accuracy. Results from toothpaste analyses using these two methods were highly correlated, indicating the potential to use the SPME extraction as an inexpensive and solventfree alternative to the LLE method.

  20. Simultaneous enantioselective determination of amphetamine and congeners in hair specimens by negative chemical ionization gas chromatography-mass spectrometry.

    PubMed

    Martins, Liliane; Yegles, Michel; Chung, Heesun; Wennig, Robert

    2005-10-15

    Enantioselective quantification of amphetamine (AM), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA) enantiomers in hair using gas chromatography-mass spectrometry (GC-MS) is described. Hair specimens were digested with 1M sodium hydroxide at 100 degrees C for 30 min and extracted by a solid phase procedure using Cleanscreen ZSDAU020. Extracted analytes were derivatised with (S)-heptafluorobutyrylprolyl chloride and the resulting diastereoisomers were quantified by GC-MS operating in the negative chemical ionization mode. Extraction yields were between 73.0 and 97.9%. Limits of detection varied in the range of 2.1-45.9 pg/mg hair, whereas the lowest limits of quantification varied between 4.3 and 91.8 pg/mg hair. Intra- and inter-assay precision and respective accuracy were acceptable. The enantiomeric ratios (R versus S) of AM, MA, MDA, MDMA and MDEA were determined in hair from suspected amphetamine abusers. Only MA and AM enantiomers were detectable in this collective and the quantification data showed in most cases higher concentrations of (R)-MA and (R)-AM than those of the corresponding (S)-enantiomers. PMID:16154523

  1. Residue determination of captan and folpet in vegetable samples by gas chromatography/negative chemical ionization-mass spectrometry.

    PubMed

    Barreda, Mercedes; López, Francisco J; Villarroya, Mercedes; Beltran, Joaquim; García-Baudín, Jose María; Hernández, Felix

    2006-01-01

    A gas chromatography/negative chemical ionization-mass spectrometry (GC/NCI-MS) method has been developed for the simultaneous determination of the fungicides captan and folpet in khaki (persimmon; flesh and peel) and cauliflower. Samples were extracted with acetone in the presence of 0.1 M zinc acetate solution in order to avoid degradation of fungicides and were purified using solid-phase extraction with divinylbenzene polymeric cartridges. Purified extracts were evaporated and dissolved in hexane prior to injection into the GC/NCI-MS system. Isotope-labeled captan and folpet were used as surrogate/internal standards, and quantification was performed using matrix-matched calibration. The method showed linear response in the concentration range tested (50-2500 ng/mL). The method was fully validated with untreated blank samples of khaki (flesh and peel) and cauliflower spiked at 0.05 and 0.5 mg/kg. Satisfactory recoveries between 82 and 106% and relative standard deviations lower than 11% in all cases (n = 5) were obtained. The limit of detection for both compounds were estimated to be 0.01 mg/kg. The developed method has been applied to treated and untreated samples collected from residue trials.

  2. IONIZED GAS KINEMATICS AT HIGH RESOLUTION. II. DISCOVERY OF A DOUBLE INFRARED CLUSTER IN II Zw 40

    SciTech Connect

    Beck, Sara; Lahad, Ohr; Turner, Jean; Lacy, John; Greathouse, Thomas

    2013-04-10

    The nearby dwarf galaxy II Zw 40 hosts an intense starburst. At the center of the starburst is a bright compact radio and infrared source, thought to be a giant dense H II region containing Almost-Equal-To 14, 000 O stars. Radio continuum images suggest that the compact source is actually a collection of several smaller emission regions. We accordingly use the kinematics of the ionized gas to probe the structure of the radio-infrared emission region. With TEXES on the NASA-IRTF we measured the 10.5 {mu}m [S IV] emission line with effective spectral resolutions, including thermal broadening, of {approx}25 and {approx}3 km s{sup -1} and spatial resolution {approx}1''. The line profile shows two distinct, spatially coextensive, emission features. The stronger feature is at galactic velocity and has FWHM 47 km s{sup -1}. The second feature is {approx}44 km s{sup -1} redward of the first and has FWHM 32 km s{sup -1}. We argue that these are two giant embedded clusters, and estimate their masses to be Almost-Equal-To 3 Multiplication-Sign 10{sup 5} M{sub Sun} and Almost-Equal-To 1.5 Multiplication-Sign 10{sup 5} M{sub Sun }. The velocity shift is unexpectedly large for such a small spatial offset. We suggest that it may arise in a previously undetected kinematic feature remaining from the violent merger that formed the galaxy.

  3. Determination of butyltin species in water and sediment by solid-phase microextraction-gas chromatography-flame ionization detection.

    PubMed

    Millán, E; Pawliszyn, J

    2000-03-17

    A procedure for determination of tetraethyltin (TeET) and tetrabutyltin (TeBT) in water by solid-phase microextraction (SPME) using the headspace approach has been developed. The method has been adapted for the simultaneous determination of mono-, di- and tributyltin species (MBT, DBT and TBT) after derivatization with sodium tetraethylborate in water and sediment samples. The analytical procedures were optimized with respect to stirring conditions, extraction time and extraction temperature. The pH and the amount of derivatizing reagent were also considered in derivatization reaction procedures. The analysis was carried out using gas chromatography equipped with flame ionization detection. The detection limits obtained for TeET and TeBT, in equilibrium conditions (room temperature for TeET and 40 degrees C for TeBT) were 28 and 20 ng/l (as Sn), respectively. The detection limit for butyltin species in water, which was limited by signals which are non-specific for the tin compounds and the sensitivity of the FID system, was found ca. 1 microg/l (as Sn). The SPME method was validated for analysis of sediments by analyzing the certified reference material PACS-2 finding a good agreement with the certified values. PMID:10757285

  4. Exploring petroleum hydrocarbons in groundwater by double solid phase extraction coupled to gas chromatography-flame ionization detector.

    PubMed

    Pindado Jiménez, Oscar; Pérez Pastor, Rosa Ma; Escolano Segovia, Olga; del Reino Querencia, Susana

    2015-01-01

    This work proposes an analytical procedure for measuring aliphatic and aromatic hydrocarbons fractions present in groundwater. In this method, hydrocarbons are solid phase extracted (SPE) twice from the groundwater and the resulting fractions are analyzed by gas chromatography with flame ionization detection. The first SPE disposes the hydrocarbons present in groundwater in organic solvents and the second SPE divides them into aliphatic and aromatic hydrocarbons. The validation study is carried out and its uncertainties are discussed. Identifying the main sources of uncertainty is evaluated through applying the bottom-up approach. Limits of detection for hydrocarbons ranges are below 5 µg L(-1), precision is not above of 30%, and acceptable recoveries are reached for aliphatic and aromatic fractions studied. The uncertainty due to volume of the sample, factor of calibration and recovery are the highest contributions. The expanded uncertainty range from 13% to 26% for the aliphatic hydrocarbons ranges and from 14% to 23% for the aromatic hydrocarbons ranges. As application, the proposed method is satisfactorily applied to a set of groundwater samples collected in a polluted area where there is evidence to present a high degree of hydrocarbons. The results have shown the range of aliphatic hydrocarbons >C21-C35 is the most abundant, with values ranging from 215 µg L(-1) to 354 µg L(-1), which it is associated to a contamination due to diesel.

  5. Simultaneous generation of quasi-monoenergetic electron and betatron X-rays from nitrogen gas via ionization injection

    SciTech Connect

    Huang, K.; Yan, W. C.; Li, M. H.; Tao, M. Z.; Ma, Y.; Zhao, J. R.; Chen, L. M.; Li, D. Z.; Chen, Z. Y.; Ge, X. L.; Liu, F.; Hafz, N. M.; Zhang, J.

    2014-11-17

    Upon the interaction of 60 TW Ti: sapphire laser pulses with 4 mm long supersonic nitrogen gas jet, a directional x-ray emission was generated along with the generation of stable quasi-monoenergetic electron beams having a peak energy of 130 MeV and a relative energy spread of ∼ 20%. The betatron x-ray emission had a small divergence of 7.5 mrad and a critical energy of 4 keV. The laser wakefield acceleration process was stimulated in a background plasma density of merely 5.4 × 10{sup 17 }cm{sup −3} utilizing ionization injection. The non-self-focusing and stable propagation of the laser pulse in the pure nitrogen gaseous plasma should be responsible for the simultaneous generation of the high-quality X-ray and electron beams. Those ultra-short and naturally-synchronized beams could be applicable to ultrafast pump-probe experiments.

  6. Determination of free amino compounds in betalainic fruits and vegetables by gas chromatography with flame ionization and mass spectrometric detection.

    PubMed

    Kugler, Florian; Graneis, Stephan; Schreiter, Pat P-Y; Stintzing, Florian C; Carle, Reinhold

    2006-06-14

    Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

  7. [Determination of 16 polychlorinated biphenyls in fish oil by gas chromatography-negative ion chemical ionization-mass spectrometry].

    PubMed

    Wang, Li; Li, Shushu; Zhang, Zhan; Wang, Shoulin; Li, Lei

    2015-08-01

    An analytical method for the simultaneous determination of 16 polychlorinated biphenyls (PCBs) in fish oil was developed. PCBs were extracted from fish oil with n-hexane, purified by sulfuric acid and determined by using gas chromatography-negative ion chemical ionization-mass spectrometry (GC-NCI-MS) in selected ion-monitoring (SIM) mode. A good linear relationship (r > 0.99) was observed with the PCBs concentrations from 0.01 µg/L to 10 µg/L, and the limits of quantification (LOQ, S/N = 10) were between 3 pg/g and 67 pg/g for different kinds of PCBs. The average recoveries ranged from 62.3% to 121.8% with the relative standard deviations ( RSDs, n = 3) smaller than 12%. Compared with the traditional pre-treatment of multiple material solid phase extraction, this new method is simple, rapid and less organic solvent usage. Meanwhile the method has good selectivity and sensitivity, and it is suitable for the determination of multiple trace PCBs in fish oil. PMID:26749866

  8. Development of a portable mass spectrometer characterized by discontinuous sample gas introduction, a low-pressure dielectric barrier discharge ionization source, and a vacuumed headspace technique.

    PubMed

    Kumano, Shun; Sugiyama, Masuyuki; Yamada, Masuyoshi; Nishimura, Kazushige; Hasegawa, Hideki; Morokuma, Hidetoshi; Inoue, Hiroyuki; Hashimoto, Yuichiro

    2013-05-21

    The present study has attempted to downscale a mass spectrometer in order to make it portable and enable onsite analysis with it. The development of a small mass spectrometer required the use of a compact pump whose displacement was small, decreasing the sensitivity of that spectrometer. To get high sensitivity with a small mass spectrometer, we have integrated novel techniques: a highly sensitive ionization source and efficient extraction of sample vapor. The low-pressure dielectric barrier discharge ionization (LP-DBDI) source made it possible to increase the conductance between the source and the mass analyzer, compared with ambient ionization sources, enhancing the efficiency of the ion transfer from the ionization source to the mass analyzer. We have also developed a vacuumed headspace method efficiently transporting the sample vapor to the ionization source. The sensitivity was further enhanced by also using a discontinuous sample gas introduction technique. A prototype portable mass spectrometer using those novel techniques was found to be sensitive enough to detect 0.1 ppm methamphetamine, 1 ppm amphetamine, 1 ppm 3,4-methylenedioxymethamphetamine, and 10 ppm cocaine in liquid.

  9. Resolved Spectroscopy of the Narrow-Line Region in NGC 1068: Kinematics of the Ionized Gas.

    PubMed

    Crenshaw; Kraemer

    2000-04-01

    We have determined the radial velocities of the [O iii]-emitting gas in the inner narrow-line region of the Seyfert 2 galaxy NGC 1068, along a slit at position angle 202 degrees, from STIS observations at a spatial resolution of 0&farcs;1 and a spectral resolving power of lambda&solm0;Deltalambda approximately 1000. We use these data to investigate the kinematics of the narrow-line region within 6&arcsec; ( approximately 430 pc) of the nucleus. The emission-line knots show evidence for radial acceleration to a projected angular distance of 1&farcs;7 in most cases, followed by deceleration that approaches the systemic velocity at a projected distance of approximately 4&arcsec;. We find that a simple kinematic model of biconical radial outflow can match the general trend of observed radial velocities. In this model, the emitting material is evacuated along the bicone axis, and the axis is inclined 5 degrees out of the plane of the sky. The acceleration of the emission-line clouds provides support for dynamical models that invoke radiation and/or wind pressure. We suggest that the deceleration of the clouds is due to their collision with a patchy and anistropically distributed ambient medium.

  10. Self-Diffusion Coefficient of a Weakly Ionized Cesium Monatomic Gas. Symmetry Effects

    NASA Astrophysics Data System (ADS)

    Bouledroua, Moncef; Tahar Bouazza, M.

    2006-11-01

    The quantum-mechanical computation of the diffusion coefficient D begins with the determination of the singlet and triplet potential-energy curves which, in this work, separate asymptotically to Cs(6s)+Cs(6s). The knowledge of these potentials should lead to the determination of the phase shifts. Ignoring the identity of the interacting atoms, the cross section effective in diffusion is calculated for one molecular symmetry and the coefficient of diffusion is determined according to the Chapman-Enskog method. In reality, the colliding atoms are identical. Thus, the wave function of the diatomic system should be symmetrized. In such a case, quantum mechanics leads to symmetric and antisymmetric diffusion cross sections, as described by Karstic and Schultz, and the average diffusion cross section is recalculated by considering the Cs nuclear spin and the statistical weight of each molecular state. The evaluation of the self-diffusion coefficient of a dilute Cs gas is in a first step carried out without considering the symmetry effects. The results are compared with those of Nieto de Castro et al. The variation law with temperature of D are further analyzed when the symmetry effects are ignored/included.

  11. Gas gain operations with single photon resolution using an integrating ionization chamber in small-angle X-ray scattering experiments

    NASA Astrophysics Data System (ADS)

    Menk, R. H.; Sarvestani, A.; Besch, H. J.; Walenta, A. H.; Amenitsch, H.; Bernstorff, S.

    2000-01-01

    In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. Initially, MicroCAT was thought of as a shielding grid (Frisch-grid) but later was used as an active electron amplification device that enables single X-ray photon resolution measurements at low fluxes even with integrating readout electronics. Moreover, the adjustable gas gain that continuously covers the entire range from pure ionization chamber mode up to high gas gains (30 000 and more) provides stable operation yielding a huge dynamic range of about 10 8 and more. First measurements on biological samples using small angle X-ray scattering techniques with synchrotron radiation will be presented.

  12. The merging dwarf galaxy UM 448: chemodynamics of the ionized gas from VLT integral field spectroscopy

    NASA Astrophysics Data System (ADS)

    James, B. L.; Tsamis, Y. G.; Barlow, M. J.; Walsh, J. R.; Westmoquette, M. S.

    2013-01-01

    ) population, and conclude that WR stars alone cannot be responsible for producing the observed N/O excess. Instead, the location and disturbed morphology of the N-enriched region suggest that interaction-induced inflow of metal-poor gas may be responsible.

  13. Ionized gas in the halos of edge-on, starburst galaxies: Data and results

    NASA Technical Reports Server (NTRS)

    Lehnert, Matthew D.; Heckman, Timothy M.

    1995-01-01

    We present narrowband H-alpha and broadband R images, as well as long-slit spectra oriented along the minor and major axes of a sample of about 50 edge-on (a/b greater than or equal to 2), infrared-warm (S(sub 60 microns)/S(sub 100 microns) greater than 0.04), infrared-bright S(sub 60 microns) greater than or equal to 5.4 Jy galaxies. The infrared luminosity of the sample ranges over 10(exp 10) - 10(exp 12) solar luminosity. The spatially resolved spectroscopy includes the measurement of velocity relative to the nuclear velocity, full width at half-maximum, total integrated flux in the profile (for those spectra taken under photometric conditions) for the lines (N II) lambda lambda 6548, 6583, (O I) lambda 6300, H-alpha, and (S II) lambda lambda 6716, 6713 and line ratios as a function of slit position along both the major and minor axes. The resolution of the spectra are between about 3 and 5 A. The spectroscopic data are presented for 5 bins along each axis -- a nuclear bin that is a sum of the CCD rows that cover the half-light diameter centered on the nucleus of the galaxy, two near-nuclear bins which are sums of the CCD rows that cover from one to two half-light radii on each side of the nucleus, and two off-nuclear bins which are sums of the rows at nuclear distances greater than two half-light radii on each side of the nucleus. Additionally, we present recession velocities, nuclear line asymmetries, rotation speeds, minor axis velocity shears, H-alpha luminosities, R-band absolute magnitudes, minor axis H-alpha `excess' and effective radii of the galaxies in h-alpha and the R continuum. We defer discussion of the properties of the emission-line gas and their correlation with the infrared properties of this sample of galaxies to a later paper and limit ourselves to a presentation of the data and analysis.

  14. Performance of a gas flow ionization detector filled with He-iso-C4H10 mixtures for STIM-T

    NASA Astrophysics Data System (ADS)

    Marques, A. C.; Fraga, M. M. F. R.; Fonte, P.; Beasley, D. G.; Cruz, C.; Alves, L. C.; da Silva, R. C.

    2015-04-01

    A cylindrical gas flow ionization chamber has been developed for measuring particle energy in Scanning Transmission Ion Microscopy Tomography (STIM-T) experiments due to its ability to withstand the direct beam. The response of a He-iso-C4H10 filled ionization detector to 2 MeV H+ and He+ beams was studied. Different operating parameters, such as concentration of isobutane (in the range of 55-100%), anode voltage, amplifier shaping time, the geometry of the detector entrance canal and the solid angle of the detector, were investigated. The stable operating plateau and the anode voltage at which the best energy resolution is attained were also determined for every gas mixture. The best energy resolution achieved so far for 2 MeV H+ and He+ static beams was ∼1.3%, which is comparable to that of Si PIN diode detectors (in the range of 15-30 keV). Computed tomography (CT) was applied to a set of STIM projections acquired with the gas ionization chamber at the IST/CTN microprobe beam line in order to visualize the 3D-mass distribution in a test structure.

  15. Reactions of metal ions and their clusters in the gas phase using laser ionization: Fourier transform mass spectrometry. Progress report, February 1, 1993--January 31, 1994

    SciTech Connect

    Freiser, B.S.

    1993-09-01

    This report focuses on progress in seven areas: (1) Gas-Phase Reactions of Fe(Benzyne){sup +} with Simple Alkyl Halides; (2) Photodissociation and Collision-Induced Dissociation of Molecular Ions From Methylphenol and Chloromethylphenol; (3) Isotopomer Differentiation Using Metal Ion Chemical Ionization Reagents; (4) Multiple Excitation Collisional Activation (MECA) in Fourier Transform Mass Spectrometry; (5) Chemistry of Fe{sup +}-Arene Ions with Halobenzenes; (6) Gas-Phase Photodissociaton Study of Ag(Benzene){sup +} and Ag(Toluene){sup +}; and (7) Reactivity of Ti{sup 2+} and V{sup 2+} with Small Alkanes.

  16. CO/H2, C/CO, OH/CO, and OH/O2 in dense interstellar gas: from high ionization to low metallicity

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Sternberg, Amiel

    2015-07-01

    We present numerical computations and analytic scaling relations for interstellar ion-molecule gas-phase chemistry down to very low metallicities (10-3 × solar), and/or up to high driving ionization rates. Relevant environments include the cool interstellar medium (ISM) in low-metallicity dwarf galaxies, early enriched clouds at the reionization and Pop-II star formation era, and in dense cold gas exposed to intense X-ray or cosmic ray sources. We focus on the behaviour for H2, CO, CH, OH, H2O and O2, at gas temperatures ˜100 K, characteristic of a cooled ISM at low metallicities. We consider shielded or partially shielded one-zone gas parcels, and solve the gas-phase chemical rate equations for the steady-state `metal-molecule abundances for a wide range of ionization parameters, ζ/n, and metallicties, Z '. We find that the OH abundances are always maximal near the H-to-H2 conversion points, and that large OH abundances persist at very low metallicities even when the hydrogen is predominantly atomic. We study the OH/O2, C/CO and OH/CO abundance ratios, from large to small, as functions of ζ/n and Z '. Much of the cold dense ISM for the Pop-II generation may have been OH-dominated and atomic rather than CO-dominated and molecular.

  17. Method development for the characterization of biofuel intermediate products using gas chromatography with simultaneous mass spectrometric and flame ionization detections.

    PubMed

    Sťávová, Jana; Stahl, Danese C; Seames, Wayne S; Kubátová, Alena

    2012-02-10

    Accurate analytical methods are required to develop and evaluate the quality of new renewable transportation fuels and intermediate organic liquid products (OLPs). Unfortunately, existing methods developed for the detailed characterization of petroleum products, are not accurate for many of the OLPs generated from non-petroleum feedstocks. In this study, a method was developed and applied to the detailed characterization of complex OLPs formed during triacylglyceride (TG) pyrolysis which is the basis for generating one class of emerging biofuels. This method uses gas chromatography coupled simultaneously with flame ionization and mass spectrometry detectors (GC-FID/MS). The FID provided accurate quantification of carbonaceous species while MS enabled identification of unknown compounds. A programed temperature vaporizer using a 25 °C, 0.1 min, 720 °C min(-1), 350 °C, 5 min temperature program is employed which minimizes compound discrimination better than the more commonly utilized split/splitless injector, as verified with injections at 250 and 350 °C. Two standard mixtures featuring over 150 components are used for accurate identification and a designed calibration standard accounts for compound discrimination at the injector and differing FID responses of various classes of compounds. This new method was used to identify and quantify over 250 species in OLPs generated from canola oil, soybean oil, and canola methyl ester (CME). In addition to hydrocarbons, the method was used to quantify polar (upon derivatization) and unidentified species, plus the unresolved complex mixture that has not typically been determined in previous studies. Repeatability of the analytical method was below 5% RSD for all individual components. Using this method, the mass balance was closed for samples derived from canola and soybean oil but only ca. 77 wt% of the OLP generated from CME could be characterized. The ability to close the mass balance depended on sample origin

  18. DECIPHERING THE IONIZED GAS CONTENT IN THE MASSIVE STAR-FORMING COMPLEX G75.78+0.34

    SciTech Connect

    Sanchez-Monge, Alvaro; Kurtz, Stan; Lizano, Susana; Palau, Aina; Estalella, Robert; Shepherd, Debra; Franco, Jose; Garay, Guido

    2013-04-01

    We present subarcsecond observations toward the massive star-forming region G75.78+0.34. We used the Very Large Array to study the centimeter continuum and H{sub 2}O and CH{sub 3}OH maser emission, and the Owens Valley Radio Observatory and Submillimeter Array to study the millimeter continuum and recombination lines (H40{alpha} and H30{alpha}). We found radio continuum emission at all wavelengths, coming from three components: (1) a cometary ultracompact (UC) H II region with an electron density {approx}3.7 Multiplication-Sign 10{sup 4} cm{sup -3}, excited by a B0 type star, and with no associated dust emission; (2) an almost unresolved UCH II region (EAST), located {approx}6'' to the east of the cometary UCH II region, with an electron density {approx}1.3 Multiplication-Sign 10{sup 5} cm{sup -3}, and associated with a compact dust clump detected at millimeter and mid-infrared wavelengths; and (3) a compact source (CORE), located {approx}2'' to the southwest of the cometary arc, with a flux density increasing with frequency, and embedded in a dust condensation of 30 M{sub Sun }. The CORE source is resolved into two compact and unresolved sources which can be well fit by two homogeneous hypercompact H II regions each one photoionized by a B0.5 zero-age main sequence star, or by free-free radiation from shock-ionized gas resulting from the interaction of a jet/outflow system with the surrounding environment. The spatial distribution and kinematics of water masers close to the CORE-N and S sources, together with excess emission at 4.5 {mu}m and the detected dust emission, suggest that the CORE source is a massive protostar driving a jet/outflow.

  19. [Determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry].

    PubMed

    Xia, Guanghui; Shen, Weijian; Yu, Keyao; Wu, Bin; Zhang, Rui; Shen, Chongyu; Zhao, Zengyun; Bian, Xiaohong; Xu, Jiyang

    2014-07-01

    A method was developed for the determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The honey and royal jelly samples were treated with different preparation methods as the result of the different components. The honey sample was extracted with ethyl acetate and cleaned up with primary second amine, and the royal jelly sample was extracted with acetonitrile-water (1:1, v/v), and cleaned up with a C18 solid-phase extraction column. Finally, the extracts of the honey and royal jelly were analyzed by GC-NCI/MS in selected ion monitoring (SIM) mode separately. External standard calibration method was used for quantification. The linearities of calibration curves of the four insecticides were good with the correlation coefficients greater than 0.99 in the range of 50-500 microg/L. The limits of the detection (LODs) of the four insecticides were in the range of 0.12- 5.0 microg/kg, and the limits of the quantification (LOQs) were in the range of 0.40-16.5 microg/kg. The recoveries of the four insecticides spiked in honey and royal jelly at three spiked levels (10, 15 and 20 microg/kg) were in the range of 78.2 -110.0%, and the relative standard deviations (RSDs) were all below 14%. The sensitivity and selectivity of this method were good with no interfering peaks. The proposed method is simple quick and effective to analyze the four insecticide residues in honey and royal jelly.

  20. HST/COS detection of a Ne VIII absorber towards PG 1407+265: an unambiguous tracer of collisionally ionized hot gas?

    NASA Astrophysics Data System (ADS)

    Hussain, T.; Muzahid, S.; Narayanan, A.; Srianand, R.; Wakker, B. P.; Charlton, J. C.; Pathak, A.

    2015-01-01

    We report the detection of Ne VIII in a zabs = 0.599 61 absorber towards the QSO PG1407+265 (zem= 0.94). Besides Ne VIII, absorption from H I Lyman series lines (H I λ1025-λ915), several other low (C II, N II, O II and S II), intermediate (C III, N III, N IV, O III, S IV and S V) and high (S VI, O VI and Ne VIII) ionization metal lines are detected. Disparity in the absorption line kinematics between different ions implies that the absorbing gas comprises of multiple ionization phases. The low and the intermediate ions (except S V) trace a compact (˜410 pc), metal-rich (Z ˜ Z⊙) and overdense (log nH ˜ -2.6) photoionized region that sustained star formation for a prolonged period. The high ions, Ne VIII and O VI, can be explained as arising in a low density (-5.3 ≤ log nH ≤ -5.0), metal-rich (Z ≳ Z⊙) and diffuse (˜180 kpc) photoionized gas. The S V, S VI and C IV [detected in the Faint Object Spectrograph (FOS) spectrum] require an intermediate photoionization phase with -4.2 < log nH < -3.5. Alternatively, a pure collisional ionization model, as used to explain the previous known Ne VIII absorbers, with 5.65 < log T < 5.72, can reproduce the S VI, O VI and Ne VIII column densities simultaneously in a single phase. However, even such models require an intermediate phase to reproduce any observable S V and/or C IV. Therefore, we conclude that when multiple phases are present, the presence of Ne VIII is not necessarily an unambiguous indication of collisionally ionized hot gas.

  1. Nearby early-type galaxies with ionized gas. VI. The Spitzer-IRS view. Basic data set analysis and empirical spectral classification

    NASA Astrophysics Data System (ADS)

    Panuzzo, P.; Rampazzo, R.; Bressan, A.; Vega, O.; Annibali, F.; Buson, L. M.; Clemens, M. S.; Zeilinger, W. W.

    2011-04-01

    Context. A large fraction of early-type galaxies (ETGs) shows emission lines in their optical spectra, mostly with LINER characteristics. Despite the number of studies, the nature of the ionization mechanisms is still debated. Many ETGs also show several signs of rejuvenation episodes. Aims: We aim to investigate the ionization mechanisms and the physical processes of a sample of ETGs using mid-infrared spectra. Methods: We present here low resolution Spitzer-IRS spectra of 40 ETGs, 18 of which from our proposed Cycle 3 observations, selected from a sample of 65 ETGs showing emission lines in their optical spectra. We homogeneously extract the mid-infrared (MIR) spectra, and after the proper subtraction of a "passive" ETG template, we derive the intensity of the ionic and molecular lines and of the polycyclic aromatic hydrocarbon (PAH) emission features. We use MIR diagnostic diagrams to investigate the powering mechanisms of the ionized gas. Results: The mid-infrared spectra of early-type galaxies show a variety of spectral characteristics. We empirically sub-divide the sample into five classes of spectra with common characteristics. Class-0, accounting for 20% of the sample, are purely passive ETGs with neither emission lines nor PAH features. Class-1 show emission lines but no PAH features, and account for 17.5% of the sample. Class-2, in which 50% of the ETGs are found, as well as having emission lines, show PAH features with unusual ratios, e.g. 7.7 μm/11.3 μm ≤ 2.3. Class-3 objects (7.5% of the sample) have emission lines and PAH features with ratios typical of star-forming galaxies. Class-4, containing only 5% of the ETGs, is dominated by a hot dust continuum. The diagnostic diagram [Ne iii]15.55 μm/[Ne ii]12.8 μm vs. [S iii]33.48 μm/[Si ii]34.82 μm, is used to investigate the different mechanisms ionizing the gas. According to the above diagram most of our ETGs contain gas ionized via either AGN-like or shock phenomena, or both. Conclusions: Most of

  2. Penning ionization electron spectra of pyrene, chrysene, and coronene in collision with metastable He(2 3S) atoms in the gas phase

    NASA Astrophysics Data System (ADS)

    Yamakita, Yoshihiro; Yamauchi, Masayo; Ohno, Koichi

    2009-01-01

    Penning ionization electron spectra (PIES) of pyrene (C16H10), chrysene (C18H12), and coronene (C24H12) in the gas phase are recorded using metastable He∗(2 3S) atoms. The assignments of PIES are presented based on the outer valence Green's function calculations with the correlation consistent polarized valence triple-ζ basis sets and the exterior electron density calculations of contributing molecular orbitals. The definite positions of all of the π bands in the PIES are identified making use of the large PIES cross sections. Broad bands are observed in low-electron-energy regions for chrysene and coronene and are ascribed to ionization processes of non-Koopmans types from σ orbitals. The anisotropic interaction potential energy surfaces for the colliding systems are obtained from ab initio model potentials for the related systems with similar outer valences Li(2 2S)+C16H10, C18H12, and C24H12, respectively. The attractive well depths in the out-of-plane directions are found to be similar between these molecules, and the repulsive walls embrace the in-plane perimeters uniformly. Collision energy dependencies for partial Penning ionization cross sections and negative peak shifts in PIES for chrysene support these anisotropic interactions. Effects from thermal populations in low-frequency vibrational modes are estimated to be minor in one-electron ionization processes.

  3. Optimization of Direct Ionization of CO2 by Controlling the Gas Flow Inside of a Beam-Target

    SciTech Connect

    Salazar Quintero, G A; Ognibene, T

    2011-03-07

    We designed and optimized a target that directs a CO{sub 2} pulse onto a Ti surface where a Cs{sup +} sputtering beam ionizes the CO{sub 2} to generate C{sup -}. These targets will be used for the direct ionization of CO{sub 2} pulses to enable the measurement of carbon isotope ratios in real time. The design was based on the results of Comsol{trademark} simulations of the target configurations.

  4. Gas-Phase Synthesis of Singly and Multiply Charged Polyoxovanadate Anions Employing Electrospray Ionization and Collision Induced Dissociation

    SciTech Connect

    Al Hasan, Naila M.; Johnson, Grant E.; Laskin, Julia

    2013-07-02

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy n– and VxOyCln– ions (x = 1–14, y = 2–36, n = 1–3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N+, tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCln– and VxOyCl(L)(n–1)– clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl(1–2)– and VxOy (1–2)– anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively

  5. Investigations of animal blood samples after fragrance drug inhalation by gas chromatography/mass spectrometry with chemical ionization and selected ion monitoring.

    PubMed

    Jirovetz, L; Jäger, W; Buchbauer, G; Nikiforov, A; Raverdino, V

    1991-12-01

    The fragrance compounds linalool (1) and linalyl acetate (2) could be detected, identified and quantified (1: 7-9 ng ml-1; and 2: 1-2 ng ml-1 and 4-5 ng ml-1 as free linalool) in blood samples after inhalation in animal experiments (mice) by gas chromatography/mass spectrometry (GC/MS) with chemical ionization (CI) (ammonia); selected ion monitoring (SIM) mode (1: m/z 81, 137 and 154; 2: 47, 57 and 137) and GC/flame ionization detection (FID). The inhalation of these monoterpenes in concentrations of 5 mg l-1 air leads to a significant reduction of the motility of the test animals down to 30-40% with respect to the control group.

  6. Simple pretreatment procedure combined with gas chromatography/multiphoton ionization/mass spectrometry for the analysis of dioxins in soil samples obtained after the Tōhoku earthquake.

    PubMed

    Chang, Yu-Ching; Imasaka, Totaro

    2013-01-01

    A simple pretreatment procedure was developed for the analysis of dioxins in soil samples using gas chromatography/multiphoton ionization/time-of-flight mass spectrometry. The sample was subjected to a pressurized liquid extraction procedure, followed by separation using a pair of Sulfoxide and Ag-ION columns for cleanup. Due to the high selectivity of laser ionization, the procedure was simplified and the time required for an analysis was decreased to 3 h. The sample collected after the earthquake and tsunami contained relatively high concentrations of PCBs and PCDD/Fs. This simple and rapid pretreatment procedure can be useful for monitoring the environment to prevent unexpected exposure of toxic dioxins for the workers who have to process more than 20 million tons of the wastes in a few years.

  7. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal

    PubMed Central

    Zuber, Jan; Kroll, Marius M.; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  8. Gas Chromatography/Atmospheric Pressure Chemical Ionization-Fourier Transform Ion Cyclotron Resonance Mass Spectrometry of Pyrolysis Oil from German Brown Coal.

    PubMed

    Zuber, Jan; Kroll, Marius M; Rathsack, Philipp; Otto, Matthias

    2016-01-01

    Pyrolysis oil from the slow pyrolysis of German brown coal from Schöningen, obtained at a temperature of 500°C, was separated and analyzed using hyphenation of gas chromatography with an atmospheric pressure chemical ionization source operated in negative ion mode and Fourier transform ion cyclotron resonance mass spectrometry (GC-APCI-FT-ICR-MS). Development of this ultrahigh-resolving analysis method is described, that is, optimization of specific GC and APCI parameters and performed data processing. The advantages of GC-APCI-FT-ICR-MS hyphenation, for example, soft ionization, ultrahigh-resolving detection, and most important isomer separation, were demonstrated for the sample liquid. For instance, it was possible to separate and identify nine different propylphenol, ethylmethylphenol, and trimethylphenol isomers. Furthermore, homologous series of different acids, for example, alkyl and alkylene carboxylic acids, were verified, as well as homologous series of alkyl phenols, alkyl dihydroxy benzenes, and alkoxy alkyl phenols. PMID:27066076

  9. Gas chromatographic determination of benzene, toluene, ethylbenzene and xylenes using flame ionization detector in water samples with direct aqueous injection up to 250 microl.

    PubMed

    Kubinec, R; Adamuscin, J; Jurdáková, H; Foltin, M; Ostrovský, I; Kraus, A; Soják, L

    2005-08-19

    A simple method of solventless extraction of volatile organic compounds (benzene, toluene, ethylbenzene and xylenes) from aqueous samples was developed. This method allows direct injection of large volume of water sample into a gas chromatograph using the sorption capacity of the sorbent Chromosorb P NAW applied directly in the injection port of gas chromatograph. The system prevent water penetration into a column, keep it adsorbed on its surface until the analytes are stripped into a column, and the residual water is purging using split flow. The limit of detection ranging from 0.6 for benzene to 1.1 microg l(-1) for o-xylene and limit of quantification ranging 2.0-3.6 microg l(-1) are lower that those reached by gas chromatography with flame ionization detection and direct aqueous injection before.

  10. Imaging spectrophotometry of ionized gas in NGC 1068. III - Anisotropic excitation of the large-scale disk by scattering of nuclear continuum

    SciTech Connect

    Sokolowski, J.; Bland-hawthorn, J.; Cecil, G. North Carolina, University, Chapel Hill )

    1991-07-01

    Photoionization of the solar abundance diffuse ionized media (DIM) in NGC 1068 by anisotropic nuclear emission is studied. It is shown that the emission characteristics can be understood in the light of the developing picture of the galaxy in which its intrinsic type 1 Seyfert nucleus, concealed by an obscuring medium, is visible only through scattered, polarized light. The gas excitation is anisotropic, the high-excitation gas along the jet axis being photoionized by direct nuclear continuum, while the lower excitation gas away from the axis sees only indirect nuclear emission scattered into it. A model of low optical depth, near-nuclear Thomson scattering is considered in detail, and it is shown that, even with moderate dust extinction, this mechanism is sufficient to energize the DIM. 56 refs.

  11. Capillary column gas chromatography, resonance enhanced multiphoton ionization, time-of-flight mass spectrometry, laser-induced fluorescence, flame ionization detection system for the determination of polynuclear aromatic compounds in complex mixtures

    SciTech Connect

    Dobson, R.L.M.

    1986-01-01

    A method is reached to fully characterize the polynuclear aromatic hydrocarbons (PAC) that have been deemed to be highly mutagenic or carcinogenic. A multidimensional, laser-based analytical instrument has been developed that, when utilized to the full extent of its capabilities could be the solution to this complex analytical problem. The overall technique is termed Capillary Column Gas Chromatography, Resonance Enhanced Multiphoton Ionization, Time-of-Flight Mass Spectrometry, Laser-induced Fluorescence, with parallel Flame Ionization Detection (CC/GC-REMPI-TOF/MS-LIF-FID). This system combines the selectivity of two complementary laser-based methods, REMPI and LIF, with an extremely powerful and proven analytical tool, GC/MS. The GC effluent passes through the ion source of a TOF/MS, where it is interrogated by a tunable ultraviolet laser beam. Thus, PAC and other absorbing species may be selectively excited and/or ionized in the presence of nonabsorbing components. All laser-analyte interaction products (actions, electrons, and photons) are simultaneously monitored utilizing the TOF/MS, a total electron current detector (TECD), and a LIF detector. The main advantage of this technique is that all analytically useful data for each absorbing chromatographic eluent may be collected on-the-fly. The simultaneous availability of this information simplifies the characterization task. The present absolute detection limits for several PAC have been determined to be low picogram range. Also, a linear dynamic range of approximately four orders of magnitude has been established for the TECD, indicating that this technique is both sensitive and quantitative. Further, the use of deuterated analogs, of selected PAC, as internal reference standards greatly assists in quantitation.

  12. The determination of PCBs in Rocky Flats Type IV waste sludge by gas chromatography/electron capture detection. Part 2

    SciTech Connect

    Parish, K.J.; Applegate, D.V.; Postlethwait, P.D.; Boparai, A.S.; Reedy, G.T.

    1994-12-01

    Before disposal, radioactive sludge (Type IV) from Rocky Flats Plant (RFP) must be evaluated for polychlorinated biphenyl (PCB) content. The Type IV sludge consists of organic solvents, degreasers, cutting oils, and transuranic (TRU) waste mixed with calcium silicate (MicroCel E{reg_sign} and Oil Dri{reg_sign} to form a grease or paste-like material. For laboratory testing, a nonradioactive simulated Type 17V RFP sludge was prepared at Argonne National Laboratory-East (ANL-E). This sludge has a composition similar to that expected from field samples. In an earlier effort, a simplified method was developed for extraction, cleanup of extract, and determination of PCBs in samples of simulated sludge spiked with Aroclors 1254 and 1260. The simplified method has now been used to determine the presence and quantities of other Aroclors in the simulated sludge, namely, Aroclors 10 1 6, 1221, 1232, 1242, and 1248. The accuracy and precision of the data for these Aroclors were found to be similar to the data for sludges spiked with Aroclors 1254 and 1260. Since actual sludges may vary in composition, the method was also verified by analyzing another source of Type IV simulated sludge, prepared by Argonne National Laboratory-West (ANL-W).

  13. Determination of PCBs in Rocky Flats Type IV waste sludge by gas chromatography/electron capture detection

    SciTech Connect

    Parish, K.J.; Applegate, D.V.; Boparai, A.S.; Reedy, G.T.

    1993-12-01

    Type IV Rocky Flats Plant (RFP) radioactive sludge samples must be evaluated for polychlorinated biphenyl (PCB) content before disposal. The Type IV sludge consists of organic solvents, degreasers, cutting oils, and transuranic (TRU) waste mixed with calcium silicate (MicroCel E{reg_sign}) and Oil Dri{reg_sign} to form a grease or paste-like material. For laboratory studies a nonradioactive simulated Type IV RFP sludge was prepared having a composition similar to that expected from field samples. A simplified method was developed for extraction, purification and analysis of PCBs using samples of simulated sludge spiked with Aroclors 1254 and 1260 (reports provided to Argonne indicated Aroclors 1254 and 1260 as the most likely PCB contaminants in RFP sludge samples). The developed method was compared to the Environmental Protection Agency (EPA) accepted SW-846 method for analysis of PCBs (Method 8081). The accuracy and precision data were found to be similar for the two methods. The developed method was also tested with samples of simulated sludge spiked with Pu (in solid and solution forms). Reduction of radioactivity in final extract versus in the spike sample ranged from a factor of 10{sup 5} to 10{sup 7}.

  14. Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

    PubMed

    Otto, Stefan; Streibel, Thorsten; Erdmann, Sabrina; Klingbeil, Sophie; Schulz-Bull, Detlef; Zimmermann, Ralf

    2015-10-15

    Polycyclic aromatic hydrocarbons (PAH), as a part of dissolved organic matter (DOM), are environmental pollutants of the marine compartment. This study investigates the origin of PAH, which is supposed to derive mainly from anthropogenic activities, and their alteration along the salinity gradient of the Baltic Sea. Pyrolysis in combination with gas chromatography and two mass selective detectors in one measurement cycle are utilized as a tool for an efficient trace analysis of such complex samples, by which it is possible to detect degradation products of high molecular structures. Along the north-south transect of the Baltic Sea a slightly rising trend for PAH is visible. Their concentration profiles correspond to the ship traffic as a known anthropogenic source, underlined by the value of special isomer ratios such as phenanthrene and anthracene (0.31-0.45) or pyrene and fluoranthene (0.44-0.53). The detection of naphthalene and the distribution of its alkylated representatives support this statement.

  15. Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

    PubMed

    Otto, Stefan; Streibel, Thorsten; Erdmann, Sabrina; Klingbeil, Sophie; Schulz-Bull, Detlef; Zimmermann, Ralf

    2015-10-15

    Polycyclic aromatic hydrocarbons (PAH), as a part of dissolved organic matter (DOM), are environmental pollutants of the marine compartment. This study investigates the origin of PAH, which is supposed to derive mainly from anthropogenic activities, and their alteration along the salinity gradient of the Baltic Sea. Pyrolysis in combination with gas chromatography and two mass selective detectors in one measurement cycle are utilized as a tool for an efficient trace analysis of such complex samples, by which it is possible to detect degradation products of high molecular structures. Along the north-south transect of the Baltic Sea a slightly rising trend for PAH is visible. Their concentration profiles correspond to the ship traffic as a known anthropogenic source, underlined by the value of special isomer ratios such as phenanthrene and anthracene (0.31-0.45) or pyrene and fluoranthene (0.44-0.53). The detection of naphthalene and the distribution of its alkylated representatives support this statement. PMID:26277803

  16. Evaluation of a novel helium ionization detector within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography.

    PubMed

    Franchina, Flavio A; Maimone, Mariarosa; Sciarrone, Danilo; Purcaro, Giorgia; Tranchida, Peter Q; Mondello, Luigi

    2015-07-10

    The present research is focused on the use and evaluation of a novel helium ionization detector, defined as barrier discharge ionization detector (BID), within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography (FM GC×GC). The performance of the BID device was compared to that of a flame ionization detector (FID), under similar FM GC×GC conditions. Following development and optimization of the FM GC×GC method, the BID was subjected to fine tuning in relation to acquisition frequency and discharge flow. Moreover, the BID performance was measured and compared to that of the FID, in terms of extra-column band broadening, sensitivity and dynamic range. The comparative study was carried out by using standard compounds belonging to different chemical classes, along with a sample of diesel fuel. Advantages and disadvantages of the BID system, also within the context of FM GC×GC, are critically discussed. In general, the BID system was characterized by a more limited dynamic range and increased sensitivity, compared to the FID. Additionally, BID and FID contribution to band broadening was found to be similar under the operational conditions applied. Particular attention was devoted to the behaviour of the FM GC×GC-BID system toward saturated and aromatic hydrocarbons, for a possible future use in the field of mineral-oil food contamination research.

  17. Evaluation of a novel helium ionization detector within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography.

    PubMed

    Franchina, Flavio A; Maimone, Mariarosa; Sciarrone, Danilo; Purcaro, Giorgia; Tranchida, Peter Q; Mondello, Luigi

    2015-07-10

    The present research is focused on the use and evaluation of a novel helium ionization detector, defined as barrier discharge ionization detector (BID), within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography (FM GC×GC). The performance of the BID device was compared to that of a flame ionization detector (FID), under similar FM GC×GC conditions. Following development and optimization of the FM GC×GC method, the BID was subjected to fine tuning in relation to acquisition frequency and discharge flow. Moreover, the BID performance was measured and compared to that of the FID, in terms of extra-column band broadening, sensitivity and dynamic range. The comparative study was carried out by using standard compounds belonging to different chemical classes, along with a sample of diesel fuel. Advantages and disadvantages of the BID system, also within the context of FM GC×GC, are critically discussed. In general, the BID system was characterized by a more limited dynamic range and increased sensitivity, compared to the FID. Additionally, BID and FID contribution to band broadening was found to be similar under the operational conditions applied. Particular attention was devoted to the behaviour of the FM GC×GC-BID system toward saturated and aromatic hydrocarbons, for a possible future use in the field of mineral-oil food contamination research. PMID:26032893

  18. Measurement of electron drift, diffusion, and effective ionization coefficients in the SF6 CHF3 and SF6 CF4 gas mixtures

    NASA Astrophysics Data System (ADS)

    de Urquijo, J.; Basurto, E.; Hernández-Ávila, J. L.

    2003-12-01

    The electron drift velocity, the longitudinal diffusion coefficient, the effective ionization coefficient and the limiting field strength for mixtures of SF6 with CHF3 and CF4 have been measured with a pulsed Townsend technique. The overall density-reduced electric field strength, E/N, could be varied between 60 and 520 Td (1 Td = 10-17 V cm2), while the SF6 content in the gas mixtures was varied over the range 1-50%. We have found that the electron drift velocity and the density-normalized longitudinal diffusion coefficient vary weakly with the amount of SF6 in the mixture. In contrast, the effective ionization coefficient shows a strong dependence with the SF6 content, becoming more electronegative as the amount of SF6 is increased. The measured limiting field strength for these two mixtures is lower than those for SF6-N2. To our knowledge, no previous ionization or electron transport data for these mixtures have been published.

  19. Defect of the well-known (classical) expression for the ionization rate in gas-discharge plasma and its modification

    NASA Astrophysics Data System (ADS)

    Litvinov, I. I.

    2015-11-01

    A critical analysis is given of the well-known expression for the electron-impact ionization rate constant α i of neutral atoms and ions, derived by linearization of the ionization cross section σ i (ɛ) as a function of the electron energy near the threshold I and containing the characteristic factor ( I + 2 kT). Using the classical Thomson expression for the ionization cross section, it is shown that in addition to the linear slope of σ i (ɛ), it is also necessary to take into account the large negative curvature of this function near the threshold. In this case, the second term in parentheses changes its sign, which means that the commonly used expression for α i (˜4 kT/I) already at moderate values of the temperature ( kT/I ˜ 0.1). The source of this error lies in a mathematical mistake in the original approach and is related to the incorrect choice of the sequential orders of terms small in the parameter kT/I. On the basis of a large amount of experimental data and considerations similar to the Gryzinski theory, a universal two-parameter modification of the Thomson formula (as well as the Bethe—Born formula) is proposed and a new simple expression for the ionization rate constant for arbitrary values of kT/I is derived.

  20. Defect of the well-known (classical) expression for the ionization rate in gas-discharge plasma and its modification

    SciTech Connect

    Litvinov, I. I.

    2015-11-15

    A critical analysis is given of the well-known expression for the electron-impact ionization rate constant α{sub i} of neutral atoms and ions, derived by linearization of the ionization cross section σ{sub i}(ε) as a function of the electron energy near the threshold I and containing the characteristic factor (I + 2kT). Using the classical Thomson expression for the ionization cross section, it is shown that in addition to the linear slope of σ{sub i}(ε), it is also necessary to take into account the large negative curvature of this function near the threshold. In this case, the second term in parentheses changes its sign, which means that the commonly used expression for α{sub i} (∼4kT/I) already at moderate values of the temperature (kT/I ∼ 0.1). The source of this error lies in a mathematical mistake in the original approach and is related to the incorrect choice of the sequential orders of terms small in the parameter kT/I. On the basis of a large amount of experimental data and considerations similar to the Gryzinski theory, a universal two-parameter modification of the Thomson formula (as well as the Bethe—Born formula) is proposed and a new simple expression for the ionization rate constant for arbitrary values of kT/I is derived.

  1. Abnormal ionization in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  2. Evidence for the Presence of a Warping of the Ionizing Gas I-Ayer Derived from H166a Emission Observations in the Outer Galaxy

    NASA Astrophysics Data System (ADS)

    Azcarate, I. N.; Cersosimo, J. C.; Colomb, F. R.

    1990-12-01

    RESUMEN Se presentan resultados de un relevamiento de Ia emisi6n de la ifnea H 1 66a en el rango de longitudes galacticas 2700 < 1 <3000 y para tres latitudes galacticas b = 0.00, b = l0.50. De los mismos, resulta que hay evidencia de un alabeo de Ia capa de gas jonizado en el plano galactico, en las partes exteriores de Ia Galaxia. ABSTRACT Results from an H166a emission survey in the Galactic longitude range 2700 < 1 <3000 and for three Galactic latitudes (b = 0.00, b = 0.50), are presented. From these results, there is evidence for the presence of a warping of the ionized gas layer in the galactic plane, in the outer Galaxy. K words: GALAXY-SThUCTURE - RADIO HNES-

  3. Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids.

    PubMed

    Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J

    2016-02-01

    The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected.

  4. Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids.

    PubMed

    Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J

    2016-02-01

    The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. PMID:26772132

  5. IONIZED GAS KINEMATICS AT HIGH RESOLUTION. V. [Ne ii], MULTIPLE CLUSTERS, HIGH EFFICIENCY STAR FORMATION, AND BLUE FLOWS IN HE 2–10

    SciTech Connect

    Beck, Sara; Turner, Jean; Lacy, John; Greathouse, Thomas

    2015-11-20

    We measured the 12.8 μm [Ne ii] line in the dwarf starburst galaxy He 2–10 with the high-resolution spectrometer TEXES on the NASA IRTF. The data cube has a diffraction-limited spatial resolution of ∼1″ and a total velocity resolution, including thermal broadening, of ∼5 km s{sup −1}. This makes it possible to compare the kinematics of individual star-forming clumps and molecular clouds in the three dimensions of space and velocity, and allows us to determine star formation efficiencies. The kinematics of the ionized gas confirm that the starburst contains multiple dense clusters. From the M/R of the clusters and the ≃30%–40% star formation efficiencies, the clusters are likely to be bound and long lived, like globulars. Non-gravitational features in the line profiles show how the ionized gas flows through the ambient molecular material, as well as a narrow velocity feature, which we identify with the interface of the H ii region and a cold dense clump. These data offer an unprecedented view of the interaction of embedded H ii regions with their environment.

  6. Application of gas chromatography/flame ionization detector-based metabolite fingerprinting for authentication of Asian palm civet coffee (Kopi Luwak).

    PubMed

    Jumhawan, Udi; Putri, Sastia Prama; Yusianto; Bamba, Takeshi; Fukusaki, Eiichiro

    2015-11-01

    Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries.

  7. Separation of aromatic solvents from oil refinery reformates by a newly designed ionic liquid using gas chromatography with flame ionization detection.

    PubMed

    Bahadur, Indra; Mabaso, Mbongeni; Redhi, Gan; Singh, Prashant; Kumar, Sudharsan; Moodley, Kandasamy

    2015-03-01

    The aim of this study was to determine whether the new ionic liquid, N,N-dimethyl-2-oxopyrrolidonium iodide, synthesized in our laboratory is a suitable solvent for the separation of aromatic components benzene, toluene, ethylbenzene, and xylenes from petroleum mixtures (reformates) in liquid-liquid extraction. In pursuance of the above aim, a method to extract all components of a mixture, containing four aromatic components simultaneously, was developed. A new ionic liquid and a previously used liquid were compared for their extraction abilities. These ionic liquids were, respectively, N,N-dimethyl-2-oxopyrrolidinium iodide and 1-ethyl-3-methyl imidazolium ethyl sulfate. The concentrations of each benzene, toluene, ethylbenzene, and xylenes component in the extract and raffinate phases were measured by gas chromatography with flame ionization detection as volume percent to determine the extraction ability of the ionic liquids. The results obtained for both the reformate samples and model mixtures indicated that the new ionic liquid was effective as an extracting solvent for the recovery of aromatic components from reformates. Also the analysis results, using gas chromatography with flame ionization detection, for the reformate samples were as good as the results obtained by a local oil refinery. The extraction results also show that the developed method is very suitable for the separation and analysis of aromatic components in reformates.

  8. Application of gas chromatography/flame ionization detector-based metabolite fingerprinting for authentication of Asian palm civet coffee (Kopi Luwak).

    PubMed

    Jumhawan, Udi; Putri, Sastia Prama; Yusianto; Bamba, Takeshi; Fukusaki, Eiichiro

    2015-11-01

    Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries. PMID:25912451

  9. Effective ionization coefficients, limiting electric fields, and electron energy distributions in CF3I + CF4 + Ar ternary gas mixtures

    NASA Astrophysics Data System (ADS)

    Tezcan, S. S.; Dincer, M. S.; Bektas, S.

    2016-07-01

    This paper reports on the effective ionization coefficients, limiting electric fields, electron energy distribution functions, and mean energies in ternary mixtures of (Trifluoroiodomethane) CF3I + CF4 + Ar in the E/N range of 100-700 Td employing a two-term solution of the Boltzmann equation. In the ternary mixture, CF3I component is increased while the CF4 component is reduced accordingly and the 40% Ar component is kept constant. It is seen that the electronegativity of the mixture increases with increased CF3I content and effective ionization coefficients decrease while the limiting electric field values increase. Synergism in the mixture is also evaluated in percentage using the limiting electric field values obtained. Furthermore, it is possible to control the mean electron energy in the ternary mixture by changing the content of CF3I component.

  10. A table-top ion and electron beam facility for ionization quenching measurement and gas detector calibration

    NASA Astrophysics Data System (ADS)

    Muraz, J. F.; Médard, J.; Couturier, C.; Fourrel, C.; Guillaudin, O.; Lamy, T.; Marton, M.; Riffard, Q.; Sortais, P.; Santos, D.; Sauzet, N.

    2016-10-01

    In the frame of the MiMAC project, the LPSC (Laboratoire de Physique Subatomique et de Cosmologie) has developed COMIMAC, a miniaturized and transportable table-top beam line, producing ions or electrons to make measurements of the "quenching" factor in ionization and detector calibration. The energy range of the COMIMAC beam facility starts from a few tens of eV up to 50 keV.

  11. Capillary column gas chromatography, resonance enhanced multiphoton ionization, time-of-flight mass spectrometry laser-induced fluorescence, flame ionization detection system for the determination of polynuclear aromatic compounds in complex mixtures

    SciTech Connect

    Dobson, R.L.M.

    1986-06-01

    Of the thousands of chemical compounds that have been deemed mutagenic or carcinogenic, it is generally agreed that the polynuclear aromatic hydrocarbons (PAC) are among the most potent. Because of the wide range of potency of PAC, even among geometric isomers and substitutional derivatives, it is important to fully characterize these samples. This task is a formidable one, usually requiring elaborate sample clean-up and fractionation prior to analysis. A multidimensional, laser-based analytical instrument has been developed that, when utilized to the full extent of its capabilities, could be the solution to this complex analytical problem. The overall technique is termed Capillary Column Gas Chromatography, Resonance Enhanced Multiphoton Ionization, Time-Of-Flight Mass Spectrometry, Laser-induced Fluorescence, with parallel Flame Ionization Detection (CC/GC-REMPI-TOF/MS-LIF-FID). This system combines the selectivity and sensitivity of two complementary laser-based methods, REMPI and LIF, with an extremely powerful and proven analytical tool, GC/MS. The GC effluent passes through the ion source of a TOF/MS, where it is interrogated by a tunable ultraviolet laser beam. All laser-analyte interaction products (cations, electrons, and photons) are simultaneously monitored utilizing the TOF/MS, a total electron current detector (TECD), and a LIF detector. The simultaneous availability of this information simplifies the characterization task. The present absolute detection limits for several PAC have been determined to be in the low picogram range. Also, a linear dynamic range of approximately four orders of magnitude has been established for the TECD, indicating that this technique is both sensitive and quantitative. Further, the use of deuterated analogs, of selected PAC, as internal reference standards greatly assists in quantitation. 219 refs., 37 figs., 13 tabs.

  12. A fast gas ionization calorimeter filled with C 3F 8 for operation at high counting rates and hard radiation environment

    NASA Astrophysics Data System (ADS)

    Denisov, S.; Dushkin, A.; Fedyakin, N.; Gilitsky, Yu.; Ljudmirsky, M.; Spiridonov, A.; Sytnik, V.

    1998-12-01

    The performance of a gas ionization EM calorimeter with planar electrodes and steel absorbers has been studied with a 26.6 GeV/ c electron beam at the 70 GeV IHEP accelerator. The design of the calorimeter is optimized for the operation at high counting rates by minimizing the coupling inductance and by choosing rather fast and heavy perfluoroalkane C 3F 8 ( vdr=0.07 mm/ns at a reduced field E/ N=1.0×10 -16 V cm 2). This gas has been used for the first time in calorimetry applications. The total calorimeter thickness is ≈21 X0. The signal readout has been done by remote 25 Ω low-noise preamplifiers coupled to towers via 25 Ω cable of 3 m length. The choice of a 25 Ω input impedance provides a complete matching between preamplifier, cable and tower. The studies of the calorimeter consisted in measuring the signal and noise spectra at different values of HV, ADC gate width and gas pressure. The electron attachment rate in C 3F 8 with a stated purity of 99.99% is quite low (at a given E/ N the mean free path of electrons is λ=2.2 cm at 1 atm). The intrinsic energy resolution of the calorimeter after noise subtraction is found to be independent of the gas pressure and equal to ≈7% at E=26.6 GeV/ c.

  13. Improved sensitivity by use of gas chromatography-positive chemical ionization triple quadrupole mass spectrometry for the analysis of drug related substances.

    PubMed

    Van Gansbeke, Wim; Polet, Michael; Hooghe, Fiona; Devos, Christophe; Van Eenoo, Peter

    2015-09-15

    In 2013, the World Anti-Doping Agency (WADA) drastically lowered the minimum required performance levels (MRPLs) of most doping substances, demanding a substantial increase in sensitivity of the existing methods. For a number of compounds, conventional electron impact ionization gas chromatography tandem mass spectrometry (GC-EI-MS/MS) is often no longer sufficient to reach these MRPLs and new strategies are required. In this study, the capabilities of positive ion chemical ionization (PICI) GC-MS/MS are investigated for a wide range of drug related compounds of various classes by injection of silylated reference standards. Ammonia as PICI reagent gas had superior characteristics for GC-MS/MS purposes than methane. Compared to GC-EI-MS/MS, PICI (with ammonia as reagent gas) provided more selective ion transitions and consequently, increased sensitivity by an average factor of 50. The maximum increase (by factor of 500-1000) was observed in the analysis of stimulants, namely chlorprenaline, furfenorex and phentermine. In total, improved sensitivity was obtained for 113 out of 120 compounds. A new GC-PICI-MS/MS method has been developed and evaluated for the detection of a wide variety of exogenous doping substances and the quantification of endogenous steroids in urine in compliance with the required MRPLs established by WADA in 2013. The method consists of a hydrolysis and extraction step, followed by derivatization and subsequent 1μL pulsed splitless injection on GC-PICI-MS/MS (16min run). The increased sensitivity allows the set up of a balanced screening method that meets the requirements for both quantitative and qualitative compounds: sufficient capacity and resolution in combination with high sensitivity and short analysis time. This resulted in calibration curves with a wide linear range (e.g., 48-9600ng/mL for androsterone and etiochanolone; all r(2)>0.99) without compromising the requirements for the qualitative compounds.

  14. Laboratory and Ambient Measurements of Oxidized Organic Compounds in the Gas Phase Using Nitrate Ion Chemical Ionization Coupled with High Resolution Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Stark, H.; Canagaratna, M. R.; Krechmer, J.; Lambe, A. T.; Isaacman-VanWertz, G. A.; Nowak, J. B.; Kimmel, J.; Kroll, J. H.; Jayne, J. T.; Worsnop, D. R.

    2015-12-01

    Chemical Ionization Mass Spectrometry (CIMS) is a widely used technique for molecular level characterization of inorganic and organic gas phase species. Here we present laboratory and ambient measurements of gaseous organic compounds by means of a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometry (HR-ToF-CIMS) using nitrate ion (NO3-) chemistry, which recently has proven capable of selectively detecting oxidized organic molecules in the gas-phase via clustering with NO3- and its high order clusters. Such low and extremely low volatility organic compounds (LVOC, ELVOC) have an important role in particulate phase chemistry and formation of secondary organic aerosol (SOA). The HR-ToF-CIMS was deployed during the Southern Oxidant and Aerosol Study (SOAS) at the forest site in Centreville, AL (June 1 - July 15, 2013), where emissions were dominated by biogenic volatile organic compounds (BVOC), occasionally mixing with anthropogenic emissions. During SOAS, the HR-ToF-CIMS detected oxidation products of both isoprene (typically C5 LVOC) and terpenes (typically C10 ELVOC). The isoprene-related LVOC showed a diurnal cycle with a day time peak, while two groups of terpene ELVOC were identified, one peaking at night and one peaking during the day. Positive Matrix Factorization (PMF) analyses are applied to the dataset to further interpret these observations. The effect of anthropogenic pollution on the biogenic-dominated environment was also investigated during periods of elevated nitrous and sulfur dioxide levels. To further aid in interpretation of the SOAS dataset, oxidized organic molecules were produced via OH and O3 initiated oxidation of biogenic gas-phase precursors in targeted laboratory studies and detected using the HR-ToF-CIMS. Spectra were obtained in these studies over a range of simulated atmospheric conditions.

  15. Improved sensitivity by use of gas chromatography-positive chemical ionization triple quadrupole mass spectrometry for the analysis of drug related substances.

    PubMed

    Van Gansbeke, Wim; Polet, Michael; Hooghe, Fiona; Devos, Christophe; Van Eenoo, Peter

    2015-09-15

    In 2013, the World Anti-Doping Agency (WADA) drastically lowered the minimum required performance levels (MRPLs) of most doping substances, demanding a substantial increase in sensitivity of the existing methods. For a number of compounds, conventional electron impact ionization gas chromatography tandem mass spectrometry (GC-EI-MS/MS) is often no longer sufficient to reach these MRPLs and new strategies are required. In this study, the capabilities of positive ion chemical ionization (PICI) GC-MS/MS are investigated for a wide range of drug related compounds of various classes by injection of silylated reference standards. Ammonia as PICI reagent gas had superior characteristics for GC-MS/MS purposes than methane. Compared to GC-EI-MS/MS, PICI (with ammonia as reagent gas) provided more selective ion transitions and consequently, increased sensitivity by an average factor of 50. The maximum increase (by factor of 500-1000) was observed in the analysis of stimulants, namely chlorprenaline, furfenorex and phentermine. In total, improved sensitivity was obtained for 113 out of 120 compounds. A new GC-PICI-MS/MS method has been developed and evaluated for the detection of a wide variety of exogenous doping substances and the quantification of endogenous steroids in urine in compliance with the required MRPLs established by WADA in 2013. The method consists of a hydrolysis and extraction step, followed by derivatization and subsequent 1μL pulsed splitless injection on GC-PICI-MS/MS (16min run). The increased sensitivity allows the set up of a balanced screening method that meets the requirements for both quantitative and qualitative compounds: sufficient capacity and resolution in combination with high sensitivity and short analysis time. This resulted in calibration curves with a wide linear range (e.g., 48-9600ng/mL for androsterone and etiochanolone; all r(2)>0.99) without compromising the requirements for the qualitative compounds. PMID:26296082

  16. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers. PMID:26486514

  17. "Magic" Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  18. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  19. Ionized gas kinematics of galaxies in the CALIFA survey. I. Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems

    NASA Astrophysics Data System (ADS)

    García-Lorenzo, B.; Márquez, I.; Barrera-Ballesteros, J. K.; Masegosa, J.; Husemann, B.; Falcón-Barroso, J.; Lyubenova, M.; Sánchez, S. F.; Walcher, J.; Mast, D.; García-Benito, R.; Méndez-Abreu, J.; van de Ven, G.; Spekkens, K.; Holmes, L.; Monreal-Ibero, A.; del Olmo, A.; Ziegler, B.; Bland-Hawthorn, J.; Sánchez-Blázquez, P.; Iglesias-Páramo, J.; Aguerri, J. A. L.; Papaderos, P.; Gomes, J. M.; Marino, R. A.; González Delgado, R. M.; Cortijo-Ferrero, C.; López-Sánchez, A. R.; Bekeraitė, S.; Wisotzki, L.; Bomans, D.

    2015-01-01

    Context. Ionized gas kinematics provide important clues to the dynamical structure of galaxies and hold constraints to the processes driving their evolution. Aims: The motivation of this work is to provide an overall characterization of the kinematic behavior of the ionized gas of the galaxies included in the Calar Alto Legacy Integral field Area (CALIFA), offering kinematic clues to potential users of the CALIFA survey for including kinematical criteria in their selection of targets for specific studies. From the first 200 galaxies observed by CALIFA survey in its two configurations, we present the two-dimensional kinematic view of the 177 galaxies satisfaying a gas content/detection threshold. Methods: After removing the stellar contribution, we used the cross-correlation technique to obtain the radial velocity of the dominant gaseous component for each spectrum in the CALIFA data cubes for different emission lines (namely, [O ii] λλ3726,3729, [O iii] λλ4959,5007, Hα+[N ii] λλ6548,6584, and [SII]λλ6716,6730). The main kinematic parameters measured on the plane of the sky were directly derived from the radial velocities with no assumptions on the internal prevailing motions. Evidence of the presence of several gaseous components with different kinematics were detected by using [O iii] λλ4959,5007 emission line profiles. Results: At the velocity resolution of CALIFA, most objects in the sample show regular velocity fields, although the ionized-gas kinematics are rarely consistent with simple coplanar circular motions. Thirty-five percent of the objects present evidence of a displacement between the photometric and kinematic centers larger than the original spaxel radii. Only 17% of the objects in the sample exhibit kinematic lopsidedness when comparing receding and approaching sides of the velocity fields, but most of them are interacting galaxies exhibiting nuclear activity (AGN or LINER). Early-type (E+S0) galaxies in the sample present clear

  20. Optical-field-ionization effects on the propagation of an ultraintense laser pulse in high- Z gas jets.

    PubMed

    Zhidkov, A; Koga, J; Esirkepov, T; Hosokai, T; Uesaka, M; Tajima, T

    2004-06-01

    Interaction of an ultraintense, a(0) >1, laser pulse with an underdense Ar plasma is analyzed via a two-dimensional particle-in-cell simulation which self-consistently includes optical-field ionization. In spite of rapid growth of ion charge Z and, hence, electron density at the laser front, relativistic self-focusing is shown to persist owing to a reduction of the expected plasma defocusing resulting from the weak radial dependence of the ion charge on laser intensity (even for Z/gamma>1 where gamma is the electron relativistic factor).

  1. New Rydberg states of gas-phase aluminum halides observed by resonance-enhanced multiphoton ionization spectroscopy

    SciTech Connect

    Hudgens, J.W.; Dearden, D.V.; Johnson, R.D. III

    1993-12-31

    The authors report detection and characterization of AlF and AlCl using 1+2, 2=1, 2+2, 3+1, and 3+2 resonance-enhanced multiphoton ionization (REMPI) spectroscopy. REMPI Spectra of AlF reveal 13 new Rydberg states that lie between 70,000 and 77,000 cm{sup {minus}1}. These new states, in combination with previously known states, form six Rydberg series. Least-squares fitting of the Rydberg series to the Rydberg equation yields the precise adiabatic ionization potential, IP{sub a}(AlF) = 9.729 {+-} 0.001 eV. Vibrational intervals of the new Rydberg states are about 25% greater than those of AlF (X {sup 1}{Sigma}{sup +}), with most lying between 930-980 cm{sup {minus}1}. REMPI spectra of AlCl reveal new Rydberg states that lie between 54000 and 60000 cm{sup {minus}1}. Vibrational intervals of these new Rydberg states are about 25% greater than those of AlCl (X {sup 1}{Sigma}{sup +}), with most lying between 570-600 cm{sup {minus}1}.

  2. Miniature Gas Chromatograph (GC): Penning Ionization Electron Spectroscopy (PIES) Instrument for the Trace Analyses of Extraterrestrial Environments

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel R.; Sheverev, Valery A.; Holland, Paul M.; Takeuchi, Norishige

    2006-01-01

    In situ exploration of the solar system to identify its early chemistry as preserved in icy bodies and to look for compelling evidence of astrobiology will require new technology for chemical analysis. Chemical measurements in space flight environments highlight the need for a high level of positive identification of chemical compounds, since re-measurement by alternative techniques for confirmation will not be feasible. It also may not be possible to anticipate all chemical species that are observed, and important species may be present only at trace levels where they can be masked by complex chemical backgrounds. Up to now, the only techniques providing independent sample identification of GC separated components across a wide range of chemical species have been Mass Spectrometry (MS) and Ion Mobility Spectrometry (IMS). We describe here the development of a versatile and robust miniature GC detector based on Penning Ionization Electron Spectroscopy (PIES), for use with miniature GC systems being developed for planetary missions. PIES identifies the sample molecule through spectra related to its ionization potential. The combination of miniature GC technology with the primary identification capabilities of PIES provides an analytical approach ideal for planetary analyses.

  3. Electrospray Ionization Mass Spectrometry

    SciTech Connect

    Kelly, Ryan T.; Marginean, Ioan; Tang, Keqi

    2014-06-13

    Electrospray Ionization (ESI) is a process whereby gas phase ions are created from molecules in solution. As a solution exits a narrow tube in the presence of a strong electric field, an aerosol of charged droplets are is formed that produces gas phase ions as they it desolvates. ESI-MS comprises the creation of ions by ESI and the determination of their mass to charge ratio (m/z) by MS.

  4. Multiresidue analysis of pesticides in traditional Chinese medicines using gas chromatography - negative chemical ionization tandem mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, a residue analysis method for the simultaneous determination of 107 pesticides in the traditional Chinese medicines (TCMs), Angelica sinensis, Angelica dahurica, Leonurus heterophyllus Sweet, Pogostemon cablin, and Lonicera japonica Thunb, was developed using gas chromatography couple...

  5. Fluorohydrogenate Cluster Ions in the Gas Phase: Electrospray Ionization Mass Spectrometry of the [1-Ethyl-3-methylimidazolium+][F(HF)2.3–] Ionic Liquid

    SciTech Connect

    Gary S. Groenewold; James E. Delmore; Michael T. Benson; Tetsuya Tsuda; Rika Hagiwara

    2013-12-01

    Electrospray ionization of the fluorohydrogenate ionic liquid [1-ethyl-3-methylimidazolium][F(HF)2.3] ionic liquid was conducted to understand the nature of the anionic species as they exist in the gas phase. Abundant fluorohydrogenate clusters were produced; however, the dominant anion in the clusters was [FHF-], and not the fluoride-bound HF dimers or trimers that are seen in solution. Density functional theory (DFT) calculations suggest that HF molecules are bound to the clusters by about 30 kcal/mol. The DFT-calculated structures of the [FHF-]-bearing clusters show that the favored interactions of the anions are with the methynic and acetylenic hydrogen atoms on the imidazolium cation, forming planar structures similar to those observed in the solid state. A second series of abundant negative ions was also formed that contained [SiF5-] together with the imidazolium cation and the fluorohydrogenate anions that originate from reaction of the spray solution with silicate surfaces.

  6. Application of elevated temperature-dispersive liquid-liquid microextraction for determination of organophosphorus pesticides residues in aqueous samples followed by gas chromatography-flame ionization detection.

    PubMed

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Rezaee Aghdam, Samaneh; Nouri, Nina; Bamorrowat, Mahdi

    2016-12-01

    In the present study, an elevated temperature, dispersive, liquid-liquid microextraction/gas chromatography-flame ionization detection was investigated for the determination, pre-concentration, and extraction of six organophosphorus pesticides (malathion, phosalone, dichlorvos, diazinon, profenofos, and chlorpyrifos) residues in fruit juice and aqueous samples. A mixture of 1,2-dibromoethane (extraction solvent) and dimethyl sulfoxide (disperser solvent) was injected rapidly into the sample solution heated at an elevated temperature. Analytical parameters, including enrichment factors (1600-2075), linearity (r>0.994), limits of detection (0.82-2.72ngmL(-1)) and quantification (2.60-7.36ngmL(-1)), relative standard deviations (<7%) and extraction recoveries (64-83%), showed the high efficiency of the method developed for analysis of the target analytes. The proposed procedure was used effectively to analyse selected analytes in river water and fruit juice, and diazinon was found at ngmL(-1) concentrations in apple juice.

  7. Fluorohydrogenate cluster ions in the gas phase: electrospray ionization mass spectrometry of the [1-ethyl-3-methylimidazolium(+)][F(HF)2.3(-)] ionic liquid.

    PubMed

    Groenewold, Gary S; Delmore, James E; Benson, Michael T; Tsuda, Tetsuya; Hagiwara, Rika

    2013-12-27

    Electrospray ionization of the fluorohydrogenate ionic liquid [1-ethyl-3-methylimidazolium][F(HF)2.3] ionic liquid was conducted to understand the nature of the anionic species as they exist in the gas phase. Abundant fluorohydrogenate clusters were produced; however, the dominant anion in the clusters was [FHF(-)], and not the fluoride-bound HF dimers or trimers that are seen in solution. Density functional theory (DFT) calculations suggest that HF molecules are bound to the clusters by about 30 kcal/mol. The DFT-calculated structures of the [FHF(-)]-bearing clusters show that the favored interactions of the anions are with the methynic and acetylenic hydrogen atoms on the imidazolium cation, forming planar structures similar to those observed in the solid state. A second series of abundant negative ions was also formed that contained [SiF5(-)] together with the imidazolium cation and the fluorohydrogenate anions that originate from reaction of the spray solution with silicate surfaces.

  8. Gas chromatography/mass spectrometric analysis of methyl esters of N,N-dialkylaminoethane-2-sulfonic acids for verification of the Chemical Weapons Convention.

    PubMed

    Pardasani, Deepak; Gupta, Arvinda K; Palit, Meehir; Shakya, Purushottam; Kanaujia, Pankaj K; Sekhar, K; Dubey, Devendra K

    2005-01-01

    This paper describes the synthesis and gas chromatography/electron ionization mass spectrometric (GC/EI-MS) analysis of methyl esters of N,N-dialkylaminoethane-2-sulfonic acids (DAESAs). These sulfonic acids are important environmental signatures of nerve agent VX and its toxic analogues, hence GC/EI-MS analysis of their methyl esters is of paramount importance for verification of the Chemical Weapons Convention. DAESAs were prepared by condensation of 2-bromoethane sulfonic acid with dialkylamines, and by condensation of dialkylaminoethyl chloride with sodium bisulfite. GC/EI-MS analysis of methyl esters of DAESAs yielded mass spectra; based on these spectra, generalized fragmentation routes are proposed that rationalize most of the characteristic ions. PMID:16196000

  9. A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

    ERIC Educational Resources Information Center

    Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

    2013-01-01

    An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

  10. Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils.

    PubMed

    Zhou, You-Ya; Yu, Ji-Fang; Yan, Zeng-Guang; Zhang, Chao-Yan; Xie, Ya-Bo; Ma, Li-Qiang; Gu, Qing-Bao; Li, Fa-Sheng

    2013-04-01

    A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 μg kg(-1) range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.

  11. Alkali metal ionization detector

    DOEpatents

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  12. Propagation of intense and short circularly polarized pulses in a molecular gas: From multiphoton ionization to nonlinear macroscopic effects

    NASA Astrophysics Data System (ADS)

    Lytova, M.; Lorin, E.; Bandrauk, A. D.

    2016-07-01

    We present a detailed analysis of the propagation dynamics of short and intense circularly polarized pulses in an aligned diatomic gas. Compared to linearly polarized intense pulses, high harmonic generation (HHG) and the coherent generation of attosecond pulses in the intense-circular-polarization case are a new research area. More specifically, we numerically study the propagation of intense and short circularly polarized pulses in the one-electron H2+ molecular gas, using a micro-macro Maxwell-Schrödinger model. In this model, the macroscopic polarization is computed from the solution of a large number of time-dependent Schrödinger equations, the source of dipole moments, and using a trace operator. We focus on the intensity and the phase of harmonics generated in the H2+ gas as a function of the pulse-propagation distance. We show that short coherent circularly polarized pulses of same helicity can be generated in the molecular gas as a result of cooperative phase-matching effects.

  13. An argon-nitrogen-hydrogen mixed-gas plasma as a robust ionization source for inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Makonnen, Yoseif; Beauchemin, Diane

    2014-09-01

    Multivariate optimization of an argon-nitrogen-hydrogen mixed-gas plasma for minimum matrix effects, while maintaining analyte sensitivity as much as possible, was carried out in inductively coupled plasma mass spectrometry. In the presence of 0.1 M Na, the 33.9 ± 3.9% (n = 13 elements) analyte signal suppression on average observed in an all-argon plasma was alleviated with the optimized mixed-gas plasma, the average being - 4.0 ± 8.8%, with enhancement in several cases. An addition of 2.3% v/v N2 in the outer plasma gas, and 0.50% v/v H2 to the central channel, as a sheath around the nebulizer gas flow, was sufficient for this drastic increase in robustness. It also reduced the background from ArO+ and Ar2+ as well as oxide levels by over an order of magnitude. On the other hand, the background from NO+ and ArN+ increased by up to an order of magnitude while the levels of doubly-charged ions increased to 7% (versus 2.7% in an argon plasma optimized for sensitivity). Furthermore, detection limits were generally degraded by 5 to 15 fold when using the mixed-gas plasma versus the argon plasma for matrix-free solution (although they were better for several elements in 0.1 M Na). Nonetheless, the drastically increased robustness allowed the direct quantitative multielement analysis of certified ore reference materials, as well as the determination of Mo and Cd in seawater, without using any matrix-matching or internal standardization.

  14. [Determination of synthetic nitro-musks in cosmetics by gas chromatography coupled with negative chemical ionization-triple quadrupole mass spectrometry].

    PubMed

    Wang, Zheng

    2012-11-01

    A confirmatory method is presented for the determination of five nitro-musks (musk ambrette, musk xylene, musk moskene, musk tibeten and musk ketone) in different cosmetics by gas chromatography coupled with negative chemical ionization (NCI)-triple quadrupole mass spectrometry (GC-MS/MS). The samples were extracted under ultrasonication using a mixture of acetone and hexane. The extract was concentrated and then cleaned up by CNWBOND Si solid phase extraction cartridge. Five different instrument parameters such as the temperature programmed, ion source temperature, reagent gas pressure, collision energy, monitoring ion pairs were optimized for higher sensitivity. Then the analytes were qualitatively and quantitatively analyzed under the multiple reaction monitoring (MRM) mode after the chromatographic separation on an HP-5MS capillary column (30 m x 0.25 mm, 0.25 microm), and employing d15-musk xylene as internal standard. The mixed standards were spiked in the blank cosmetics samples (each nitro-musk was about 500 ng/kg), and the recoveries were in the range of 85.81%-103.77% with the relative standard deviations (RSDs) not more than 5.32%. The limits of quantification of the method were about 50.0-500 ng/kg. The method is accurate, rapid, sensitive and can be used in the inspection of the five nitro-musks in cosmetics.

  15. [Coupling of gas chromatography with single photon ionization time-of-flight mass spectrometry and its application to characterization of compounds in diesel].

    PubMed

    Xie, Yuanyuan; Hua, Lei; Chen, Ping; Hou, Keyong; Jiang, Jichun; Wang, Yan; Li, Haiyang

    2015-02-01

    A novel analytical method coupling gas chromatography (GC) with single photon ionization time-of-flight mass spectrometry (SPI-TOF MS) has been developed. First of all, a double-wall-tube transfer line was built to combine GC with SPI-TOF MS, which realized seamless connection between GC and SPI ion source. Based on this, standard n-pentadecane and benzene/toluene/xylene standard gas mixtures were used to study important voltage parameters of the ion source. After the optimization of the ion source voltages, pure molecular ion peaks of the analytes were obtained in the mass spectra and qualitative analysis of different kinds of organic compounds were eventually realized rapidly and accurately. At last, GC/SPI-TOF MS was applied to the characterization of volatile and semvolatile organic compounds in diesel and two-dimensional spectra of GC×SPI-TOF MS were obtained. Without complicated spectra interpretation and data processing, volatile and semi-volatile organic compounds in diesel have been classified qualitatively by ion mass-to-charge ratio (m/z) in SPI mass spectra, including aliphatic compounds, aromatic compounds and nitrogen-containing compounds with low concentration such as benzopyrroles. Isomeric compounds in diesel were separated and identified by retention times of chromatographic peaks. The results indicate that the proposed analytical method of GC/SPI-TOF MS is suitable for the characterization of complicated samples such as diesel and environmental pollutants with easy operation and high efficiency.

  16. Development of a High-Resolution H3O+ Chemical Ionization Mass Spectrometer for Gas-phase Hydrocarbons and its Application During the 2015 SONGNEX Aircraft Campaign

    NASA Astrophysics Data System (ADS)

    Koss, A.; Yuan, B.; De Gouw, J. A.; Warneke, C.; Stark, H.

    2015-12-01

    In-situ time-of-flight chemical ionization mass spectrometers (ToF-CIMS) using H3O+ reagent ion chemistry (PTR-MS) are a relatively new technique in detection of gas-phase hydrocarbons, and recent improvements in instrument sensitivity, mass resolution, and ease of field deployment have expanded their use in atmospheric chemistry. The comparatively low-energy H3O+ ionization technique is ideal for measuring complex mixtures of hydrocarbons, and, compared to conventional quadrupole PTRMS, the newest generation of ToF-CIMS measure many more species simultaneously and with a sensitivity that is as high as a quadrupole PTR-MS. We describe here the development of a commercially available ToF CIMS into an H3O+CIMS suitable for deployment on aircraft, and its application during an aircraft campaign studying emissions from oil and natural gas extraction industry. We provide an overview of instrument development and specifications, including design, characterization, and field operation. We then discuss data processing and interpretation. First, we investigate determination of intensities of poorly resolved peaks. The mass resolution of the present instrument (m/Δm ~4500) enables separate analysis of many isobaric peaks, but peaks are also frequently not fully resolved. Using results from laboratory tests, we quantify how the accuracy can be limited by the overlap in neighboring peaks, and compare to theoretical predictions from literature. We then briefly describe our method for quality assurance of reported compounds, and correction for background and humidity effects. Finally, we present preliminary results from the first field deployment of this instrument during the Spring 2015 SONGNEX aircraft campaign. This campaign sampled emissions from oil and natural gas extraction regions and associated infrastructure in the Western and Central United States. We will highlight results that illustrate (1) new scientific capability from improved mass resolution, which

  17. Diffuse low-ionization gas in the galactic halo casts doubts on z ≃ 0.03 WHIM detections

    NASA Astrophysics Data System (ADS)

    Nicastro, F.; Senatore, F.; Gupta, A.; Mathur, S.; Krongold, Y.; Elvis, M.; Piro, L.

    2016-05-01

    In this Letter, we demonstrate that the two claims of z ≃ 0.03 O VII K α absorption lines from Warm Hot Intergalactic Medium (WHIM) along the lines of sight to the blazars H 2356-309 (Buote et al.; Fang et al.) and Mkn 501 (Ren, Fang & Buote) are likely misidentifications of the z = 0 O II K β line produced by a diffuse Low-Ionization Metal Medium in the Galaxy's interstellar and circum-galactic mediums. We perform detailed modelling of all the available high signal-to-noise Chandra Low Energy Transmission Grating (LETG) and XMM-Newton Reflection Grating Spectrometer (RGS) spectra of H 2356-309 and Mkn 501 and demonstrate that the z ≃ 0.03 WHIM absorption along these two sightlines is statistically not required. Our results, however, do not rule out a small contribution from the z ≃ 0.03 O VII K α absorber along the line of sight to H 2356-309. In our model the temperature of the putative z = 0.031 WHIM filament is T = 3 × 105 K and the O VII column density is N_{O VII} ≲ 4× 10^{15} cm-2, twenty times smaller than the O VIIcolumn density previously reported, and now more consistent with the expectations from cosmological hydrodynamical simulations.

  18. Warp or lag? The ionized and neutral hydrogen gas in the edge-on dwarf galaxy UGC 1281

    NASA Astrophysics Data System (ADS)

    Kamphuis, P.; Peletier, R. F.; van der Kruit, P. C.; Heald, G. H.

    2011-07-01

    The properties of gas in the haloes of galaxies constrain global models of the interstellar medium. Kinematical information is of particular interest since it is a clue to the origin of the gas. Until now mostly massive galaxies have been investigated for their halo properties. Here we report on deep H I and Hα observations of the edge-on dwarf galaxy UGC 1281 in order to determine the existence of extraplanar gas and the kinematics of this galaxy. This is the first time a dwarf galaxy is investigated for its gaseous halo characteristics. We have obtained Hα integral field spectroscopy using PPAK at Calar Alto and deep H I observations with the Westerbork Synthesis Radio Telescope (WSRT) of this edge-on dwarf galaxy. These observations are compared to 3D models in order to determine the distribution of H I in the galaxy. We find that UGC 1281 has Hα emission up to 25 arcsec (655 pc) in projection above the plane and in general a low Hα flux. Compared to other dwarf galaxies UGC 1281 is a normal dwarf galaxy with a slowly rising rotation curve that flattens off at 60 km s-1 and a central depression in its H I distribution. Its H I extends 70 arcsec (1.8 kpc) in projection from the plane. This gas can be explained by either a warp partially in the line-of-sight or a purely edge-on warp with rotational velocities that decline with a vertical gradient of 10.6 ± 3.7 km s-1 kpc-1. The line-of-sight warp model is the preferred model as it is conceptually simpler. In either model the warp starts well within the optical radius.

  19. Warp or Lag? The Ionized and Neutral Hydrogen Gas in the Edge-on Dwarf Galaxy UGC 1281

    NASA Astrophysics Data System (ADS)

    Kamphuis, P.; Peletier, R. F.; van der Kruit, P. C.; Heald, G. H.

    The properties of gas in the halos of galaxies tell us something about the properties of the interstellar medium. Here we report on deep HI and Hα observations of UGC 1281 in order to determine the existence of extra planar gas and its kinematics. This is the first time the halo characteristics of a dwarf galaxy have been investigated. These observations are compared to 3D models in order to determine the distribution of HI in the galaxy. We find that UGC 1281 has Hα emission up to 25 '' (655 pc,˜0.6 Hα hR) in projection above the plane and in general a low Hα flux. Its HI extends 70 '' (1.8 kpc,˜1.5 HI hR) in projection from the plane. This neutral extra-planar gas can be explained by either a line-of-sight warp or a thick disk with rotational velocities that decline with a vertical gradient of 10.6±3.7 km s-1 kpc-1. The line-of-sight warp model is the preferred model as it is conceptually simpler. In either model the warp starts well within the optical radius.

  20. Highly sensitive and selective analysis of urinary steroids by comprehensive two-dimensional gas chromatography combined with positive chemical ionization quadrupole mass spectrometry

    PubMed Central

    Zhang, Ying; Tobias, Herbert J.; Brenna, J. Thomas

    2014-01-01

    Comprehensive two dimensional gas chromatography (GC×GC) provides greater separation space than conventional GC. Because of fast peak elution, a time of flight mass spectrometer (TOFMS) is the usual structure-specific detector of choice. The quantitative capabilities of a novel GC×GC fast quadrupole MS were investigated with electron ionization (EI), and CH4 or NH3 positive chemical ionization (PCI) for analysis of endogenous urinary steroids targeted in anti-doping tests. Average precisions for steroid quantitative analysis from replicate urine extractions were 6% (RSD) for EI and 8% for PCI-NH3. The average limits of detection (LOD) calculated by quantification ions for 12 target steroids spiked into steroid-free urine matrix (SFUM) were 2.6 ng mL−1 for EI, 1.3 ng mL−1 for PCI-CH4, and 0.3 ng mL−1 for PCI-NH3, all in mass scanning mode. The measured limits of quantification (LOQ) with full mass scan GC×GC-qMS were comparable with the LOQ values measured by one-dimensional GC-MS in single ion monitoring (SIM) mode. PCI-NH3 yields fewer fragments and greater (pseudo)molecular ion abundances than EI or PCI-CH4. These data show a benchtop GC×GC-qMS system has the sensitivity, specificity, and resolution to analyze urinary steroids at normal urine concentrations, and that PCI-NH3, not currently available on most GC×GC-TOFMS instruments, is of particular value for generation of structure-specific ions. PMID:22606686

  1. ON THE ORIGINS OF THE DIFFUSE H{alpha} EMISSION: IONIZED GAS OR DUST-SCATTERED H{alpha} HALOS?

    SciTech Connect

    Seon, Kwang-Il; Witt, Adolf N.

    2012-10-20

    It is known that the diffuse H{alpha} emission outside of bright H II regions not only are very extended, but also can occur in distinct patches or filaments far from H II regions, and the line ratios of [S II] {lambda}6716/H{alpha} and [N II] {lambda}6583/H{alpha} observed far from bright H II regions are generally higher than those in the H II regions. These observations have been regarded as evidence against the dust-scattering origin of the diffuse H{alpha} emission (including other optical lines), and the effect of dust scattering has been neglected in studies on the diffuse H{alpha} emission. In this paper, we reexamine the arguments against dust scattering and find that the dust-scattering origin of the diffuse H{alpha} emission cannot be ruled out. As opposed to the previous contention, the expected dust-scattered H{alpha} halos surrounding H II regions are, in fact, in good agreement with the observed H{alpha} morphology. We calculate an extensive set of photoionization models by varying elemental abundances, ionizing stellar types, and clumpiness of the interstellar medium (ISM) and find that the observed line ratios of [S II]/H{alpha}, [N II]/H{alpha}, and He I {lambda}5876/H{alpha} in the diffuse ISM accord well with the dust-scattered halos around H II regions, which are photoionized by late O- and/or early B-type stars. We also demonstrate that the H{alpha} absorption feature in the underlying continuum from the dust-scattered starlight ({sup d}iffuse galactic light{sup )} and unresolved stars is able to substantially increase the [S II]/H{alpha} and [N II]/H{alpha} line ratios in the diffuse ISM.

  2. Gas chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization for fluorotelomer alcohols and perfluorinated sulfonamides determination.

    PubMed

    Portolés, Tania; Rosales, Luis E; Sancho, Juan V; Santos, F Javier; Moyano, Encarnación

    2015-09-25

    Ionization and in source-fragmentation behavior of four fluorotelomer alcohols (FTOH) (4:2 FTOH, 6:2 FTOH, 8:2 FTOH and 10:2 FTOH) and four N-alkyl fluorooctane sulfonamides/-ethanols (N-MeFOSA, N-EtFOSA, N-MeFOSE and N-EtFOSE) by APCI has been studied and compared with the traditionally used EI and CI. Protonated molecule was the base peak of the APCI spectrum in all cases giving the possibility of selecting it as a precursor ion for MS/MS experiments. Following, CID fragmentation showed common product ions for all FOSAs/FOSEs (C4F7 and C3F5). Nevertheless, the different functionality gave characteristic pattern fragmentations. For instance, FTOHs mainly loss H2O+HF, FOSAs showed the losses of SO2 and HF while FOSEs showed the losses of H2O and SO2. Linearity, repeatability and LODs have been studied obtaining instrumental LODs between 1 and 5fg. Finally, application to river water and influent and effluent waste water samples has been carried out in order to investigate the improvements in detection capabilities of this new source in comparison with the traditionally used EI/CI sources. Matrix effects in APCI have been evaluated in terms of signal enhancement/suppression when comparing standards in solvent and matrix. No matrix effects were observed and concentrations found in samples were in the range of 1-100pgL(-1) far below the LODs achieved with methods previously reported. Unknown related perfluoroalkyl substances, as methyl-sulfone and methyl-sulfoxide analogues for FTOHs, were also discovered and tentatively identified.

  3. Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

    PubMed

    Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

    2015-06-01

    A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

  4. Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

    PubMed

    Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

    2015-06-01

    A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

  5. Comparison and validation of 2 analytical methods for the determination of free fatty acids in dairy products by gas chromatography with flame ionization detection.

    PubMed

    Mannion, David T; Furey, Ambrose; Kilcawley, Kieran N

    2016-07-01

    Accurate quantification of free fatty acids (FFA) in dairy products is important for quality control, nutritional, antimicrobial, authenticity, legislative, and flavor purposes. In this study, the performance of 2 widely used gas chromatographic flame ionization detection methods for determination of FFA in dairy products differing in lipid content and degree of lipolysis were evaluated. We used a direct on-column approach where the isolated FFA extract was injected directly and a derivatization approach where the FFA were esterified in the injector to methyl esters using tetramethylammonium hydroxide as a catalyst. A comprehensive validation was undertaken to establish method linearity, limits of detection, limits of quantification, accuracy, and precision. Linear calibrations of 3 to 700mg/L (R(2)>0.999) and 20 to 700mg/L (R(2)>0.997), and limits of detection and limits of quantification of 0.7 and 3mg/L and 5 and 20mg/L were obtained for the direct injection on-column and the derivatization method, respectively. Intraday precision of 1.5 to 7.2% was obtained for both methods. The direct injection on-column method had the lower levels of limits of detection and quantification, because FFA are directly injected onto the GC as opposed to the split injection used in the derivatization method. However, the direct injection on-column method experienced accumulative column phase deterioration and irreversible FFA absorption because of the acidic nature of the injection extract, which adversely affected method robustness and the quantification of some longer chain FFA. The derivatization method experienced issues with quantification of butyric acid at low concentrations because of coelution with the injection solvent peak, loss of polyunsaturated FFA due to degradation by tetramethylammonium hydroxide, and the periodic emergence of by-product peaks of the tetramethylammonium hydroxide reaction that interfered with the quantification of some short-chain FFA. The

  6. Total OH reactivity measurements using a new fast Gas Chromatographic Photo-Ionization Detector (GC-PID)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Sinha, V.; Bockisch, S.; Klüpfel, T.; Williams, J.

    2012-12-01

    The primary and most important oxidant in the atmosphere is the hydroxyl radical (OH). Currently OH sinks, particularly gas phase reactions, are poorly constrained. One way to characterize the overall sink of OH is to measure directly the ambient loss rate of OH, the total OH reactivity. To date, direct measurements of total OH reactivity have been either performed using a Laser-Induced Fluorescence (LIF) system ("pump-and-probe" or "flow reactor") or the Comparative Reactivity Method (CRM) with a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS). Both techniques require large, complex and expensive detection systems. This study presents a feasibility assessment for CRM total OH reactivity measurements using a new detector, a Gas Chromatographic Photoionization Detector (GC-PID). Such a system is smaller, more portable, less power consuming and less expensive than other total OH reactivity measurement techniques. Total OH reactivity is measured by the CRM using a competitive reaction between a reagent (here pyrrole) with OH alone and in the presence of atmospheric reactive molecules. The new CRM method for total OH reactivity has been tested with parallel measurements of the GC-PID and the previously validated PTR-MS as detector for the reagent pyrrole during laboratory experiments, plant chamber and boreal field studies. Excellent agreement of both detectors was found when the GC-PID was operated under optimum conditions. Time resolution (60-70 s), sensitivity (LOD 3-6 s-1) and overall uncertainty (25% in optimum conditions) for total OH reactivity were similar to PTR-MS based total OH reactivity measurements. One drawback of the GC-PID system was the steady loss of sensitivity and accuracy during intensive measurements lasting several weeks, and a possible toluene interference. Generally, the GC-PID system has been shown to produce closely comparable results to the PTR-MS and thus in suitable environments (e.g. forests) it presents a viably economical

  7. Development, optimization, validation and application of faster gas chromatography - flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils.

    PubMed

    Zubair, Abdulrazaq; Pappoe, Michael; James, Lesley A; Hawboldt, Kelly

    2015-12-18

    This paper presents an important new approach to improving the timeliness of Total Petroleum Hydrocarbon (TPH) analysis in the soil by Gas Chromatography - Flame Ionization Detector (GC-FID) using the CCME Canada-Wide Standard reference method. The Canada-Wide Standard (CWS) method is used for the analysis of petroleum hydrocarbon compounds across Canada. However, inter-laboratory application of this method for the analysis of TPH in the soil has often shown considerable variability in the results. This could be due, in part, to the different gas chromatography (GC) conditions, other steps involved in the method, as well as the soil properties. In addition, there are differences in the interpretation of the GC results, which impacts the determination of the effectiveness of remediation at hydrocarbon-contaminated sites. In this work, multivariate experimental design approach was used to develop and validate the analytical method for a faster quantitative analysis of TPH in (contaminated) soil. A fractional factorial design (fFD) was used to screen six factors to identify the most significant factors impacting the analysis. These factors included: injection volume (μL), injection temperature (°C), oven program (°C/min), detector temperature (°C), carrier gas flow rate (mL/min) and solvent ratio (v/v hexane/dichloromethane). The most important factors (carrier gas flow rate and oven program) were then optimized using a central composite response surface design. Robustness testing and validation of model compares favourably with the experimental results with percentage difference of 2.78% for the analysis time. This research successfully reduced the method's standard analytical time from 20 to 8min with all the carbon fractions eluting. The method was successfully applied for fast TPH analysis of Bunker C oil contaminated soil. A reduced analytical time would offer many benefits including an improved laboratory reporting times, and overall improved clean up

  8. Development, optimization, validation and application of faster gas chromatography - flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils.

    PubMed

    Zubair, Abdulrazaq; Pappoe, Michael; James, Lesley A; Hawboldt, Kelly

    2015-12-18

    This paper presents an important new approach to improving the timeliness of Total Petroleum Hydrocarbon (TPH) analysis in the soil by Gas Chromatography - Flame Ionization Detector (GC-FID) using the CCME Canada-Wide Standard reference method. The Canada-Wide Standard (CWS) method is used for the analysis of petroleum hydrocarbon compounds across Canada. However, inter-laboratory application of this method for the analysis of TPH in the soil has often shown considerable variability in the results. This could be due, in part, to the different gas chromatography (GC) conditions, other steps involved in the method, as well as the soil properties. In addition, there are differences in the interpretation of the GC results, which impacts the determination of the effectiveness of remediation at hydrocarbon-contaminated sites. In this work, multivariate experimental design approach was used to develop and validate the analytical method for a faster quantitative analysis of TPH in (contaminated) soil. A fractional factorial design (fFD) was used to screen six factors to identify the most significant factors impacting the analysis. These factors included: injection volume (μL), injection temperature (°C), oven program (°C/min), detector temperature (°C), carrier gas flow rate (mL/min) and solvent ratio (v/v hexane/dichloromethane). The most important factors (carrier gas flow rate and oven program) were then optimized using a central composite response surface design. Robustness testing and validation of model compares favourably with the experimental results with percentage difference of 2.78% for the analysis time. This research successfully reduced the method's standard analytical time from 20 to 8min with all the carbon fractions eluting. The method was successfully applied for fast TPH analysis of Bunker C oil contaminated soil. A reduced analytical time would offer many benefits including an improved laboratory reporting times, and overall improved clean up

  9. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

  10. In-Line Ozonation for Sensitive Air-Monitoring of a Mustard-Gas Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry.

    PubMed

    Okumura, Akihiko

    2015-09-01

    A highly sensitive method for real-time air-monitoring of mustard gas (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified air containing a HD simulant, 2-chloroethyl ethyl sulfide (2CEES), was mixed with ozone and then analyzed by using an atmospheric pressure chemical ionization ion trap tandem mass spectrometer. Mass-spectral ion peaks attributable to protonated molecules of intact, monooxygenated, and dioxygenated 2CEES (MH(+), MOH(+), and MO(2)H(+), respectively) were observed. As ozone concentration was increased from zero to 30 ppm, the signal intensity of MH(+) sharply decreased, that of MOH(+) increased once and then decreased, and that of MO(2)H(+) sharply increased until reaching a plateau. The signal intensity of MO(2)H(+) at the plateau was 40 times higher than that of MH(+) and 100 times higher than that of MOH(+) in the case without in-line ozonation. Twenty-ppm ozone gas was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO(2)H(+) signal in the concentration range up to 60 μg/m(3), which is high enough for hygiene management. In the low concentration range lower than 3 μg/m(3), which is equal to the short-term exposure limit for HD, calibration plots unexpectedly fell off the linear calibration curve, but 0.6-μg/m(3) vapor was actually detected with the signal-to-noise ratio of nine. Ozone was generated from instrumentation air by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.

  11. Ultra-trace level analysis of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate by gas chromatography with multi-mode inlet, and flame ionization detection.

    PubMed

    Luong, J; Shellie, R A; Cortes, H; Gras, R; Hayward, T

    2012-03-16

    Steam condensate water treatment is a vital and integral part of the overall cooling water treatment process. Steam condensate often contains varying levels of carbon dioxide and oxygen which acts as an oxidizer. Carbon dioxide forms corrosive carbonic acid when dissolved in condensed steam. To neutralize the harmful effect of the carbonic acid, volatile amine compounds such as morpholine, cyclohexylamine, and diethylaminoethanol are often employed as part of a strategy to control corrosion in the water treatment process. Due to the high stability of these compounds in a water matrix, the indirect addition of such chemicals into the process via steam condensate often results in their presence throughout the process and even into the final product. It is therefore important to understand the impact of these chemicals and their fate within a chemical plant. The ability to analyze such compounds by gas chromatography has historically been difficult due to the lack of chromatographic system inertness at the trace level concentrations especially in an aqueous matrix. Here a highly sensitive, practical, and reliable gas chromatographic approach is described for the determination of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate at the part-per-billion (ppb) levels. The approach does not require any sample enrichment or derivatization. The technique employs a multi-mode inlet operating in pulsed splitless mode with programmed inlet temperature for sample introduction, an inert base-deactivated capillary column for solute separation and flame ionization detection. Chromatographic performance was further enhanced by the incorporation of 2-propanol as a co-solvent. Detection limits for morpholine, cyclohexylamine, diethylaminoethanol were established to be 100 ppb (v/v), with relative standard deviations (RSD) of less than 6% at the 95% confidence level (n=20) and a percent recovery of 96% or higher for the solutes of interest over a range of 0

  12. In-Line Ozonation for Sensitive Air-Monitoring of a Mustard-Gas Simulant by Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Okumura, Akihiko

    2015-09-01

    A highly sensitive method for real-time air-monitoring of mustard gas (bis(2-chloroethyl) sulfide, HD), which is a lethal blister agent, is proposed. Humidified air containing a HD simulant, 2-chloroethyl ethyl sulfide (2CEES), was mixed with ozone and then analyzed by using an atmospheric pressure chemical ionization ion trap tandem mass spectrometer. Mass-spectral ion peaks attributable to protonated molecules of intact, monooxygenated, and dioxygenated 2CEES (MH+, MOH+, and MO2H+, respectively) were observed. As ozone concentration was increased from zero to 30 ppm, the signal intensity of MH+ sharply decreased, that of MOH+ increased once and then decreased, and that of MO2H+ sharply increased until reaching a plateau. The signal intensity of MO2H+ at the plateau was 40 times higher than that of MH+ and 100 times higher than that of MOH+ in the case without in-line ozonation. Twenty-ppm ozone gas was adequate to give a linear calibration curve for 2CEES obtained by detecting the MO2H+ signal in the concentration range up to 60 μg/m3, which is high enough for hygiene management. In the low concentration range lower than 3 μg/m3, which is equal to the short-term exposure limit for HD, calibration plots unexpectedly fell off the linear calibration curve, but 0.6-μg/m3 vapor was actually detected with the signal-to-noise ratio of nine. Ozone was generated from instrumentation air by using a simple and inexpensive home-made generator. 2CEES was ozonated in 1-m extended sampling tube in only 1 s.

  13. The Application of Chemical Derivatization in Forensic Drug Chemistry for Gas and High-Performance Liquid Chromatographic Methods of Analysis.

    PubMed

    Moore, J M

    1990-12-01

    The analyses of solid-dosage forensic drug samples can be enhanced by chemical derivatization followed by gas chromatography or high-performance liquid chromatography. Using these techniques permits improved detection and chromatography of some illicit drugs and their manufacturing by-products. This review focuses on the use of chemical derivatization in conjunction with gas chromatography-flame ionization detection, gas chromatography-electron capture detection, gas chromatography-mass spectrometry, high-performance liquid chromatography-ultraviolet detection and high-performance liquid chromatography-fluorescence detection in the analysis of illicit drug samples. These drugs include the amphetamines, barbiturates, cannabis, fentanyls, opium, and hallucinogens. Discussion on sensitivity enhancement and determination of enantiomeric composition using gas chromatography and high-performance liquid chromatography is included. An entire section is devoted to the chemical derivatization and chromatographic analyses of manufacturing by-products found in illicit amphetamine and methamphetamine, heroin, and cocaine samples. This review also includes a section that describes practical elements and experimental design associated with chemical derivatization-chromatographic analyses..

  14. Separation and determination of benzene, toluene, ethylbenzene and o-xylene compounds in water using directly suspended droplet microextraction coupled with gas chromatography-flame ionization detector.

    PubMed

    Sarafraz-Yazdi, A; Amiri, A H; Es'haghi, Z

    2009-05-15

    The directly suspended droplet microextraction (DSDME) technique coupled with the capillary gas chromatography-flame ionization detector (GC-FID) was used to determine BTEX compounds in aqueous samples. The effective parameters such as organic solvent, extraction time, microdroplet volume, salt effect and stirring speed were optimized. The performance of the proposed technique was evaluated for the determination of BTEX compounds in natural water samples. Under the optimal conditions the enrichment factors ranged from 142.68 to 312.13, linear range; 0.01-20 microg mL(-1), limits of detection; 0.8-7 ng mL(-1) for most analytes. Relative standard deviations for 0.2 microg mL(-1) of BTEX in water were in the range 1.81-2.47% (n=5). The relative recoveries of BTEX from surface water at spiking level of 0.2 microg mL(-1) were in the range of 89.87-98.62%.

  15. Quantification of trace fatty acid methyl esters in diesel fuel by using multidimensional gas chromatography with electron and chemical ionization mass spectrometry.

    PubMed

    Webster, R L; Rawson, P M; Evans, D J; Marriott, P J

    2016-07-01

    Measurement of contamination of marine and naval diesel fuels (arising from product mixing or adulteration) with biodiesel or fatty acid methyl esters can be problematic, especially at very low levels. A suitable solution for this task for trace amounts of individual fatty acid methyl esters with resolution and quantification can be achieved by using a multidimensional gas chromatographic approach with electron and chemical ionization mass spectrometric detection. A unique column set comprising a 100 m methyl-siloxane nonpolar first dimension column and high-temperature ionic liquid column in the second dimension enabled identification of individual fatty acid methyl esters at below the lowest concentrations required to be reported in a diesel fuel matrix. Detection limits for individual fatty acid methyl esters compounds ranged from 0.5 to 5.0 mg/L, with excellent linearity up to 5000 mg/L and repeatability of the method from 1.3 to 3.2%. The method was applied to the analysis of diesel fuel samples with suspected biodiesel contamination. Contamination at 568 mg/L was calculated for an unknown sample and interpretation of the results permitted the determination of a likely source of the contamination. PMID:27159197

  16. Dispersive micro-solid phase extraction combined with gas chromatography-chemical ionization mass spectrometry for the determination of N-nitrosamines in swimming pool water samples.

    PubMed

    Fu, Ssu-Chieh; Tzing, Shin-Hwa; Chen, Hsin-Chang; Wang, Yu-Chen; Ding, Wang-Hsien

    2012-02-01

    A simple sample pretreatment technique, dispersive micro-solid phase extraction, was applied for the extraction of N-nitrosodimethylamine (NDMA) and other four N-nitrosamines (NAs) from samples of swimming pool water. The parameters affecting the extraction efficiency were systematically investigated. The best extraction conditions involved immersing 75 mg of carbon molecular sieve, Carboxen™ 1003 (as an adsorbent), in a 50-mL water sample (pH 7.0) containing 5% sodium chloride in a sample tube. After 20 min of extraction by vigorous shaking, the adsorbent was collected on a filter and the NAs desorbed by treatment with 150 μL of dichloromethane. A 10-μL aliquot was then directly determined by large-volume injection gas chromatography with chemical ionization mass spectrometry using the selected ion storage mode. The limits of quantitation were <0.9 ng/L. The precision for these analytes, as indicated by relative standard deviations, were <8% for both intra- and inter-day analyses. Accuracy, expressed as the mean extraction recovery, was between 62% and 109%. A preliminary analysis of swimming pool water samples revealed that NDMA was present in the highest concentration, in the range from n.d. to 100 ng/L. PMID:22222914

  17. Prediction of response factors for gas chromatography with flame ionization detection: Algorithm improvement, extension to silylated compounds, and application to the quantification of metabolites

    PubMed Central

    de Saint Laumer, Jean‐Yves; Leocata, Sabine; Tissot, Emeline; Baroux, Lucie; Kampf, David M.; Merle, Philippe; Boschung, Alain; Seyfried, Markus

    2015-01-01

    We previously showed that the relative response factors of volatile compounds were predictable from either combustion enthalpies or their molecular formulae only 1. We now extend this prediction to silylated derivatives by adding an increment in the ab initio calculation of combustion enthalpies. The accuracy of the experimental relative response factors database was also improved and its population increased to 490 values. In particular, more brominated compounds were measured, and their prediction accuracy was improved by adding a correction factor in the algorithm. The correlation coefficient between predicted and measured values increased from 0.936 to 0.972, leading to a mean prediction accuracy of ± 6%. Thus, 93% of the relative response factors values were predicted with an accuracy of better than ± 10%. The capabilities of the extended algorithm are exemplified by (i) the quick and accurate quantification of hydroxylated metabolites resulting from a biodegradation test after silylation and prediction of their relative response factors, without having the reference substances available; and (ii) the rapid purity determinations of volatile compounds. This study confirms that Gas chromatography with a flame ionization detector and using predicted relative response factors is one of the few techniques that enables quantification of volatile compounds without calibrating the instrument with the pure reference substance. PMID:26179324

  18. Quantification of trace fatty acid methyl esters in diesel fuel by using multidimensional gas chromatography with electron and chemical ionization mass spectrometry.

    PubMed

    Webster, R L; Rawson, P M; Evans, D J; Marriott, P J

    2016-07-01

    Measurement of contamination of marine and naval diesel fuels (arising from product mixing or adulteration) with biodiesel or fatty acid methyl esters can be problematic, especially at very low levels. A suitable solution for this task for trace amounts of individual fatty acid methyl esters with resolution and quantification can be achieved by using a multidimensional gas chromatographic approach with electron and chemical ionization mass spectrometric detection. A unique column set comprising a 100 m methyl-siloxane nonpolar first dimension column and high-temperature ionic liquid column in the second dimension enabled identification of individual fatty acid methyl esters at below the lowest concentrations required to be reported in a diesel fuel matrix. Detection limits for individual fatty acid methyl esters compounds ranged from 0.5 to 5.0 mg/L, with excellent linearity up to 5000 mg/L and repeatability of the method from 1.3 to 3.2%. The method was applied to the analysis of diesel fuel samples with suspected biodiesel contamination. Contamination at 568 mg/L was calculated for an unknown sample and interpretation of the results permitted the determination of a likely source of the contamination.

  19. Orthogonal array optimization of microwave-assisted derivatization for determination of trace amphetamine and methamphetamine using negative chemical ionization gas chromatography-mass spectrometry.

    PubMed

    Chung, Li-Wen; Lin, Keh-Liang; Yang, Thomas Ching-Cherng; Lee, Maw-Rong

    2009-05-01

    An orthogonal array design (OAD) was applied to optimize microwave-assisted derivatization (MAD) for analysis of trace amphetamine (AM) and methamphetamine (MA) by negative chemical ionization gas chromatography-mass spectrometry (NCI GC-MS). The 2,3,4,5,6-pentafluorobenzoyl chloride (PFBC) was used as a derivatization reagent. Experimental factors including solvent, microwave power, and irradiation time at four-levels were studied in 16 trials by OAD(16) (4(4)). The significance of these factors was investigated using analysis of variance (ANOVA) and percent contribution (PC). Solvent is statistically demonstrated a chief factor; microwave power and irradiation time are secondary factors. Under the optimum condition, calibration curve of AM is linear over a range from 0.01 to 100 ng mL(-1) with correlation coefficient 0.9988, and MA from 0.1 to 1000 ng mL(-1) with correlation coefficient 0.9951. The limit of detection (LOD) is 1.20 pg mL(-1) for AM and 13.04 pg mL(-1) for MA. An applicability of the method was tested by analyzing urine samples from amphetamine-type stimulants (ATS)-abusing suspects. Consequently, the OAD method not only optimizes the MAD condition for determination of trace AM and MA, but identifies the effects of factor solvent, microwave power and irradiation time on the MAD performance.

  20. A novel ultrasound-assisted back extraction reverse micelles method coupled with gas chromatography-flame ionization detection for determination of aldehydes in heated edibles oils.

    PubMed

    Ramezani, Zahra; Mirzajani, Roya; Kardani, Fatemeh

    2015-12-01

    A novel ultrasound-assisted back extraction reverse micelles coupled with gas chromatography-flame ionization detection has been developed for the extraction and determination of some short chain aldehydes in different heated edible oil samples. After the homogenization of the oil samples with Triton X-100, 200 μL of methanol was added to facilitate the phase separation. The aqueous micelle phase has been separated by centrifugation, then it was treated with a mixture of H2O: CHCl3 and ultrasonic vibration, were used to effectively back-extraction of the analytes into the chloroform phase. The sedimented organic phase was obtained after centrifugation, withdrawn into the microsyringe and directly injected into the GC-FID system. The calibration graphs were linear in the range 0.05-20 mg L(-1). The limits of detection were in the range of 0.02-0.15 mg L(-1). This procedure was successfully applied for determination of propanal, butanal, hexanal and heptanal in real heated oil samples. PMID:26041160

  1. Determination of three antidepressants in urine using simultaneous derivatization and temperature-assisted dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection.

    PubMed

    Nabil, Ali Akbar Alizadeh; Nouri, Nina; Farajzadeh, Mir Ali

    2015-07-01

    This paper presents a fast and simple method for the extraction, preconcentration and determination of fluvoxamine, nortriptyline and maprotiline in urine using simultaneous derivatization and temperature-assisted dispersive liquid-liquid microextraction (TA-DLLME) followed by gas chromatography-flame ionization detection (GC-FID). An appropriate mixture of dimethylformamide (disperser solvent), 1,1,2,2-tetrachloroethane (extraction solvent) and acetic anhydride (derivatization agent) was rapidly injected into the heated sample. Then the solution was cooled to room temperature and cloudy solution formed was centrifuged. Finally a portion of the sedimented phase was injected into the GC-FID. The effect of several factors affecting the performance of the method, including the selection of suitable extraction and disperser solvents and their volumes, volume of derivatization agent, temperature, salt addition, pH and centrifugation time and speed were investigated and optimized. Figures of merit of the proposed method, such as linearity (r(2)  > 0.993), enrichment factors (820-1070), limits of detection (2-4 ng mL(-1)) and quantification (8-12 ng mL(-1)), and relative standard deviations (3-6%) for both intraday and interday precisions (concentration = 50 ng mL(-1)) were satisfactory for determination of the selected antidepressants. Finally the method was successfully applied to determine the target pharmaceuticals in urine.

  2. Determination of alkyltrimethylammonium surfactants in hair conditioners and fabric softeners by gas chromatography-mass spectrometry with electron-impact and chemical ionization.

    PubMed

    Tsai, Pei-Chuan; Ding, Wang-Hsien

    2004-02-20

    The commercial hair conditioners and fabric softeners were analyzed for the content of alkyltrimethylammonium compounds (ATMACs) by gas chromatography-mass spectrometry (GC-MS) with electron impact (EI) and low-pressure positive-ion chemical ionization (PICI) modes. The method involves mixed diluted samples (adjust pH to 10.0) with potassium iodide to enhance the extraction of iodide-ATMA+ ion pairs by direct liquid-liquid extraction. The iodide-ATMA+ pairs were then demethylated to their corresponding nonionic alkyldimethylamines (ADMAs) by thermal decomposition in a GC injection-port. A high abundance of ADMAs was detected at the temperature above 300 degrees C in the GC injection-port. The enhanced selectivity of quasi-molecular ion chromatograms of C12-C18-ADMA, obtained using methanol PICI-MS enables ADMAs to be identified. The accuracy and precision of the method was validated and was successfully applied to determine contents of ATMAC in commercial hair conditioners and fabric softeners. The contents of total measured ATMAC ranged from 0.4 to 6.9% for hair conditioners, and from 3.3 to 4.6% for fabric softeners. PMID:14971489

  3. Measurements of gas-phase inorganic and organic acids from biomass fires by negative-ion proton-transfer chemical-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Veres, Patrick; Roberts, James M.; Burling, Ian R.; Warneke, Carsten; de Gouw, Joost; Yokelson, Robert J.

    2010-12-01

    Emissions from 34 laboratory biomass fires were investigated at the combustion facility of the U.S. Department of Agriculture Fire Sciences Laboratory in Missoula, Montana. Gas-phase organic and inorganic acids were quantified using negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), open-path Fourier transform infrared spectroscopy (OP-FTIR), and proton-transfer-reaction mass spectrometry (PTR-MS). NI-PT-CIMS is a novel technique that measures the mass-to-charge ratio (m/z) of ions generated from reactions of acetate (CH3C(O)O-) ions with inorganic and organic acids. The emission ratios for various important reactive acids with respect to CO were determined. Emission ratios for isocyanic acid (HNCO), 1,2 and 1,3-benzenediols (catechol, resorcinol), nitrous acid (HONO), acrylic acid, methacrylic acid, propionic acid, formic acid, pyruvic acid, and glycolic acid were measured from biomass burning. Our measurements show that there is a significant amount of HONO in fresh smoke. The NI-PT-CIMS measurements were validated by comparison with OP-FTIR measurements of HONO and formic acid (HCOOH) and with PTR-MS measurements of HCOOH.

  4. Hollow fiber liquid-phase microextraction coupled with gas chromatography-flame ionization detection for the profiling of fatty acids in vegetable oils.

    PubMed

    Siang, Gan Hui; Makahleh, Ahmad; Saad, Bahruddin; Lim, Boey Peng

    2010-12-24

    The development of a two phase hollow fiber liquid-phase microextraction technique, followed by gas-chromatography-flame ionization detection (GC-FID) for the profiling of the fatty acids (FAs) (lauric, myristic, palmitic, stearic, palmitoleic, oleic, linoleic, linolenic and arachidic) in vegetable oils is described. Heptadecanoic acid methyl ester was used as the internal standard. The FAs were transesterified to their corresponding methyl esters prior to the extraction. Extraction parameters such as type of extracting solvent, temperature, extraction time, stirring speed and salt addition were studied and optimized. Recommended conditions were extraction solvent, n-tridecane; extraction time, 35 min; extraction temperature, ambient; without addition of salt. Enrichment factors varying from 37 to 115 were achieved. Calibration curves for the nine FAs were well correlated (r(2)>0.994) within the range of 10-5000 μg L(-1). The limit of detection (signal:noise, 3) was 4.73-13.21 ng L(-1). The method was successfully applied to the profiling of the FAs in palm oils (crude, olein, kernel, and carotino cooking oil) and other vegetable oils (soybean, olive, coconut, rice bran and pumpkin). The encouraging enrichments achieved offer an interesting option for the profiling of the minor and major FAs in palm and other vegetable oils. PMID:21081239

  5. Determination of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in poultry and porcine muscle and liver by gas chromatography-negative chemical ionization mass spectrometry.

    PubMed

    Shen, Jianzhong; Xia, Xi; Jiang, Haiyang; Li, Cun; Li, Jiancheng; Li, Xiaowei; Ding, Shuangyang

    2009-05-15

    A sensitive and reliable method using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS) was developed for the simultaneous determination of chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF), and florfenicol amine (FFA) at trace levels in muscle and liver. Before extraction with ethyl acetate, CAP-d(5) was added to tissue samples as internal standard. The organic extracts were frozen to remove lipid and further purified by liquid-liquid extraction (LLE) with hexane and solid-phase extraction (SPE) using Oasis HLB cartridges. The target compounds were derivatized with BSTFA+1% TMCS prior to GC-NCI/MS determination in selected ion monitoring mode (SIM). The recovery values ranged from 78.5 to 105.5%, with relative standard deviations (RSD) <17%. The limits of detections (LODs) of 0.1 microg/kg for CAP and 0.5 microg/kg for TAP, FF, and FFA were obtain. Incurred sample and samples from local market were successfully analyzed using this method. PMID:19395324

  6. Pentafluorobenzyl esterification of haloacetic acids in tap water for simple and sensitive analysis by gas chromatography/mass spectrometry with negative chemical ionization.

    PubMed

    Zhao, Can; Fujii, Yukiko; Yan, Junxia; Harada, Kouji H; Koizumi, Akio

    2015-01-01

    Chlorine is the most widely used disinfectant for control of waterborne diseases in drinking water treatment. It can react with natural organic matter in water and form haloacetic acids (HAAs). For analysis of HAA levels, derivatization with diazomethane is commonly recommended as the standard methodology in Japan. However, diazomethane is a carcinogenic alkylating agent. Therefore, in this study, a safe, simple, and sensitive quantification method was developed to monitor HAAs in drinking water. Pentafluorobenzyl esterification was used for pretreatment. The pentafluorobenzyl-ester derivative was detected by gas chromatography-negative ion chemical ionization-mass spectrometry analysis with very high sensitivity for HAAs analysis. The method has low detection limits (8-94 ng L(-1)) and good recovery rates (89-99%) for HAAs. The method was applied to 30 tap water samples from 15 cities in the Kansai region of Japan. The levels of HAAs detected were in the range 0.54-7.83 μg L(-1). Dichloroacetic acid, trichloroacetic acid, and bromochloroacetic acid were the major HAAs detected in most of the tap water, and accounted for 29%, 20% and 19% of the total HAAs, respectively. This method could be used for routine monitoring of HAAs in drinking water without exposure of workers to occupational hazards.

  7. Determination of amantadine in biological fluids using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection.

    PubMed

    Farajzadeh, Mir Ali; Nouri, Nina; Alizadeh Nabil, Ali Akbar

    2013-12-01

    A one-step derivatization and microextraction technique for the determination of amantadine in the human plasma and urine samples is presented. An appropriate mixture of methanol (disperser solvent), 1,2-dibromoethane (extraction solvent), and butylchloroformate (derivatization agent) is rapidly injected into samples. After centrifuging, the sedimented phase is analyzed by gas chromatography-flame ionization detection (GC-FID). The kind of extraction and disperser solvents and their volumes, amount of derivatization agent and reaction/extraction time which are effective in derivatization/dispersive liquid-liquid microextraction (DLLME) procedure are optimized. Under the optimal conditions, the enrichment factor (EF) of the target analyte was obtained to be 408 and 420, and limit of detection (LOD) 4.2 and 2.7ngmL(-1), in plasma and urine respectively. The linear range is 14-5000 and 8.7-5000ng/mL for plasma and urine, respectively (squared correlation coefficient≥0.990). The relative recoveries obtained for the spiked plasma and urine samples are between 72% and 93%. Moreover, the inter- and intra-day precisions are acceptable at all spiked concentrations (relative standard deviation <7%). Finally the method was successfully applied to determine amantadine in biological samples. PMID:24157523

  8. [Determination of anilines in environmental water samples by simultaneous derivatization and ultrasound assisted emulsification microextraction combined with gas chromatography-flame ionization detectors].

    PubMed

    Tian, Li-Xun; Dai, Zhi-Xi; Wang, Guo-Dong; Weng, Huan-Xin

    2015-02-01

    This research demonstrated a new method, simultaneous derivatization and ultrasound assisted emulsification microextraction combined with gas chromatography-flame ionization detector (SD-USAEME-GC-FID), for the determination of anilines in environmental water samples. In this study, several factors, such as the volume of butylchloroformate (as derivatization agent/ extraction solvent), ultrasonication time, solution pH, salt addition, and centrifuging time and speed, were optimized in order to obtain good method performance. As a result, under the optimal conditions, the method showed good linearity in the concentration range of 6-60 000 μg x L(-1) with correlation coefficients (R2) ranging from 0.999 7 to 0.999 9 for the five target anilines. The limit of detection ( LOD) , based on signal to noise ratio of 3 , ranged from 1.1-4.1 μg x L(-1). The relative standard deviations (RSD) varied from 2.4% to 5.7% (n = 6) and the enrichment factors (EF) ranged from 317 to 846. The proposed method was also successfully applied to analyze seven environmental water samples, with the relative recoveries (RR) ranging from 86.8% to 105.5%. In a conclusion, this method was convenient, highly sensitive, inexpensive and environment-friendly, and therefore, the present method can be used as a preferred method for the determination of anilines in environmental water samples. PMID:26031106

  9. Application of elevated temperature-dispersive liquid-liquid microextraction for determination of organophosphorus pesticides residues in aqueous samples followed by gas chromatography-flame ionization detection.

    PubMed

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Rezaee Aghdam, Samaneh; Nouri, Nina; Bamorrowat, Mahdi

    2016-12-01

    In the present study, an elevated temperature, dispersive, liquid-liquid microextraction/gas chromatography-flame ionization detection was investigated for the determination, pre-concentration, and extraction of six organophosphorus pesticides (malathion, phosalone, dichlorvos, diazinon, profenofos, and chlorpyrifos) residues in fruit juice and aqueous samples. A mixture of 1,2-dibromoethane (extraction solvent) and dimethyl sulfoxide (disperser solvent) was injected rapidly into the sample solution heated at an elevated temperature. Analytical parameters, including enrichment factors (1600-2075), linearity (r>0.994), limits of detection (0.82-2.72ngmL(-1)) and quantification (2.60-7.36ngmL(-1)), relative standard deviations (<7%) and extraction recoveries (64-83%), showed the high efficiency of the method developed for analysis of the target analytes. The proposed procedure was used effectively to analyse selected analytes in river water and fruit juice, and diazinon was found at ngmL(-1) concentrations in apple juice. PMID:27374524

  10. Mapping the Ionization State of Laser-Irradiated Ar Gas Jets With Multi-Wavelength Monochromatic X-Ray Imaging

    SciTech Connect

    Kugland, N L; Doppner, T; Kemp, A; Schaeffer, D; Glenzer, S H; Niemann, C

    2010-04-08

    Two-dimensional monochromatic images of fast-electron stimulated Ar K{alpha} and He-{alpha} x-ray self-emission have recorded a time-integrated map of the extent of Ar{sup {approx}6+} and Ar{sup 16+} ions, respectively, within a high density (10{sup 20} cm{sup -3} atomic density) Ar plasma. This plasma was produced by irradiating a 2 mm wide clustering Ar gas jet with an ultra-high intensity (10{sup 19} W/cm{sup 2}, 200 fs) Ti:Sapphire laser operating at 800 nm. Spherically bent quartz crystals in the 200 (for K{alpha}) and 201 (for He-{alpha}) planes were used as near-normal incidence reflective x-ray optics. We see that a large (830 {micro}m long) region of plasma emits K{alpha} primarily along the laser axis, while the He-{alpha} emission is confined to smaller hot spot (230 {micro}m long) region that likely corresponds to the focal volume of the f/8 laser beam. X-ray spectra from a Bragg spectrometer operating in the von Hamos geometry, which images in one dimension, indicate that the centroids of the K{alpha} and He-{alpha} emission regions are separated by approximately 330 {micro}m along the laser axis.

  11. Ionization detection system for aerosols

    DOEpatents

    Jacobs, Martin E.

    1977-01-01

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber.

  12. IONIZATION CHAMBER

    DOEpatents

    Redman, W.C.; Shonka, F.R.

    1958-02-18

    This patent describes a novel ionization chamber which is well suited to measuring the radioactivity of the various portions of a wire as the wire is moved at a uniform speed, in order to produce the neutron flux traverse pattern of a reactor in which the wire was previously exposed to neutron radiation. The ionization chamber of the present invention is characterized by the construction wherein the wire is passed through a tubular, straight electrode and radiation shielding material is disposed along the wire except at an intermediate, narrow area where the second electrode of the chamber is located.

  13. Rapid analysis of six phthalate esters in wine by ultrasound-vortex-assisted dispersive liquid-liquid micro-extraction coupled with gas chromatography-flame ionization detector or gas chromatography-ion trap mass spectrometry.

    PubMed

    Cinelli, Giuseppe; Avino, Pasquale; Notardonato, Ivan; Centola, Angela; Russo, Mario Vincenzo

    2013-03-26

    An Ultrasound-Vortex-Assisted Dispersive Liquid-Liquid Micro-Extraction (USVADLLME) procedure coupled with Gas Chromatography-Flame Ionization Detector (GC-FID) or Gas Chromatography-Ion Trap Mass Spectrometry (GC-IT/MS) is proposed for rapid analysis of six phthalate esters in hydroalcoholic beverages (alcohol by volume, alc vol(-1), ≤40%). Under optimal conditions, the enrichment factor of the six analytes ranges from 220- to 300-fold and the recovery from 85% to 100.5%. The limit of detection (LOD) and limit of quantification (LOQ) are ≥0.022 μg L(-1) and ≥0.075 μg L(-1), respectively. Intra-day and inter-day precisions expressed as relative standard deviation (RSD), are ≤8.2% and ≤7.0%, respectively. The whole proposed methodology has demonstrated to be simple, reproducible and sensible for the determination of trace phthalate esters in red and white wine samples. PMID:23498123

  14. Ionization oscillations in Hall accelerators

    NASA Astrophysics Data System (ADS)

    Barral, S.; Peradzyński, Z.

    2010-01-01

    The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.

  15. Resonance ionization for analytical spectroscopy

    DOEpatents

    Hurst, George S.; Payne, Marvin G.; Wagner, Edward B.

    1976-01-01

    This invention relates to a method for the sensitive and selective analysis of an atomic or molecular component of a gas. According to this method, the desired neutral component is ionized by one or more resonance photon absorptions, and the resultant ions are measured in a sensitive counter. Numerous energy pathways are described for accomplishing the ionization including the use of one or two tunable pulsed dye lasers.

  16. The Relationship between the Dense Neutral and Diffuse Ionized Gas in the Thick Disks of Two Edge-on Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Rueff, Katherine M.; Howk, J. Christopher; Pitterle, Marissa; Hirschauer, Alec S.; Fox, Andrew J.; Savage, Blair D.

    2013-03-01

    We present high-resolution, optical images (BVI + Hα) of the multiphase interstellar medium (ISM) in the thick disks of the edge-on spiral galaxies NGC 4013 and NGC 4302. Our images from the Hubble Space Telescope (HST), Large Binocular Telescope, and WIYN 3.5 m telescope reveal an extensive population of filamentary dust absorption seen to z ~2-2.5 kpc. Many of these dusty thick disk structures have characteristics reminiscent of molecular clouds found in the Milky Way disk. Our Hα images show that the extraplanar diffuse ionized gas (DIG) in these galaxies is dominated by a smooth, diffuse component. The strongly filamentary morphologies of the dust absorption have no counterpart in the smoothly distributed Hα emission. We argue that the thick disk DIG and dust-bearing filaments trace physically distinct phases of the thick disk ISM, the latter tracing a dense, warm or cold neutral medium. The dense, dusty matter in the thick disks of spiral galaxies is largely tracing matter ejected from the thin disk via energetic feedback from massive stars. The high densities of the gas may be a result of converging gas flows. This dense material fuels some thick disk star formation, as evidenced by the presence of thick disk H II regions. Based on observations obtained with the NASA/ESA Hubble Space Telescope operated at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Also, based on data acquired using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the US, Italy, and Germany. LBT Corporation partners are the University of Arizona, on behalf of the Arizona University System; Instituto Nazionale do Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max Planck Society, the Astrophysical Institute of Potsdam, and Heidelberg University; Ohio State University, and the Research Corporation, on

  17. Gas chromatography fractionation platform featuring parallel flame-ionization detection and continuous high-resolution analyte collection in 384-well plates.

    PubMed

    Jonker, Willem; Clarijs, Bas; de Witte, Susannah L; van Velzen, Martin; de Koning, Sjaak; Schaap, Jaap; Somsen, Govert W; Kool, Jeroen

    2016-09-01

    Gas chromatography (GC) is a superior separation technique for many compounds. However, fractionation of a GC eluate for analyte isolation and/or post-column off-line analysis is not straightforward, and existing platforms are limited in the number of fractions that can be collected. Moreover, aerosol formation may cause serious analyte losses. Previously, our group has developed a platform that resolved these limitations of GC fractionation by post-column infusion of a trap solvent prior to continuous small-volume fraction collection in a 96-wells plate (Pieke et al., 2013 [17]). Still, this GC fractionation set-up lacked a chemical detector for the on-line recording of chromatograms, and the introduction of trap solvent resulted in extensive peak broadening for late-eluting compounds. This paper reports advancements to the fractionation platform allowing flame ionization detection (FID) parallel to high-resolution collection of a full GC chromatograms in up to 384 nanofractions of 7s each. To this end, a post-column split was incorporated which directs part of the eluate towards FID. Furthermore, a solvent heating device was developed for stable delivery of preheated/vaporized trap solvent, which significantly reduced band broadening by post-column infusion. In order to achieve optimal analyte trapping, several solvents were tested at different flow rates. The repeatability of the optimized GC fraction collection process was assessed demonstrating the possibility of up-concentration of isolated analytes by repetitive analyses of the same sample. The feasibility of the improved GC fractionation platform for bioactivity screening of toxic compounds was studied by the analysis of a mixture of test pesticides, which after fractionation were subjected to a post-column acetylcholinesterase (AChE) assay. Fractions showing AChE inhibition could be unambiguously correlated with peaks from the parallel-recorded FID chromatogram. PMID:27485151

  18. Partial least squares analysis of rocket propulsion fuel data using diaphragm valve-based comprehensive two-dimensional gas chromatography coupled with flame ionization detection.

    PubMed

    Freye, Chris E; Fitz, Brian D; Billingsley, Matthew C; Synovec, Robert E

    2016-06-01

    The chemical composition and several physical properties of RP-1 fuels were studied using comprehensive two-dimensional (2D) gas chromatography (GC×GC) coupled with flame ionization detection (FID). A "reversed column" GC×GC configuration was implemented with a RTX-wax column on the first dimension ((1)D), and a RTX-1 as the second dimension ((2)D). Modulation was achieved using a high temperature diaphragm valve mounted directly in the oven. Using leave-one-out cross-validation (LOOCV), the summed GC×GC-FID signal of three compound-class selective 2D regions (alkanes, cycloalkanes, and aromatics) was regressed against previously measured ASTM derived values for these compound classes, yielding root mean square errors of cross validation (RMSECV) of 0.855, 0.734, and 0.530mass%, respectively. For comparison, using partial least squares (PLS) analysis with LOOCV, the GC×GC-FID signal of the entire 2D separations was regressed against the same ASTM values, yielding a linear trend for the three compound classes (alkanes, cycloalkanes, and aromatics), yielding RMSECV values of 1.52, 2.76, and 0.945 mass%, respectively. Additionally, a more detailed PLS analysis was undertaken of the compounds classes (n-alkanes, iso-alkanes, mono-, di-, and tri-cycloalkanes, and aromatics), and of physical properties previously determined by ASTM methods (such as net heat of combustion, hydrogen content, density, kinematic viscosity, sustained boiling temperature and vapor rise temperature). Results from these PLS studies using the relatively simple to use and inexpensive GC×GC-FID instrumental platform are compared to previously reported results using the GC×GC-TOFMS instrumental platform.

  19. Validation of a qualitative screening method for pesticides in fruits and vegetables by gas chromatography quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization.

    PubMed

    Portolés, T; Mol, J G J; Sancho, J V; López, Francisco J; Hernández, F

    2014-08-01

    A wide-scope screening method was developed for the detection of pesticides in fruit and vegetables. The method was based on gas chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer with an atmospheric pressure chemical ionization source (GC-(APCI)QTOF MS). A non-target acquisition was performed through two alternating scan events: one at low collision energy and another at a higher collision energy ramp (MS(E)). In this way, both protonated molecule and/or molecular ion together with fragment ions were obtained in a single run. Validation was performed according to SANCO/12571/2013 by analysing 20 samples (10 different commodities in duplicate), fortified with a test set of 132 pesticides at 0.01, 0.05 and 0.20mg kg(-1). For screening, the detection was based on one diagnostic ion (in most cases the protonated molecule). Overall, at the 0.01mg kg(-1) level, 89% of the 2620 fortifications made were detected. The screening detection limit for individual pesticides was 0.01mg kg(-1) for 77% of the pesticides investigated. The possibilities for identification according to the SANCO criteria, requiring two ions with a mass accuracy ≤±5ppm and an ion-ratio deviation ≤±30%, were investigated. At the 0.01mg kg(-1) level, identification was possible for 70% of the pesticides detected during screening. This increased to 87% and 93% at the 0.05 and 0.20mg kg(-1) level, respectively. Insufficient sensitivity for the second ion was the main reason for the inability to identify detected pesticides, followed by deviations in mass accuracy and ion ratios.

  20. Analytical method validation for the determination of 2,3,3,3-tetrafluoropropene in air samples using gas chromatography with flame ionization detection.

    PubMed

    Mawn, Michael P; Kurtz, Kristine; Stahl, Deborah; Chalfant, Richard L; Koban, Mary E; Dawson, Barbara J

    2013-01-01

    A new low global warming refrigerant, 2,3,3,3-tetrafluoro propene, or HFO-1234yf, has been successfully evaluated for automotive air conditioning, and is also being evaluated for stationary refrigeration and air conditioning systems. Due to the advantageous environmental properties of HFO-1234yf versus HFC-134a, coupled with its similar physical properties and system performance, HFO-1234yf is also being evaluated to replace HFC-134a in refrigeration applications where neat HFC-134a is currently used. This study reports on the development and validation of a sampling and analytical method for the determination of HFO-1234yf in air. Different collection media were screened for desorption and simulated sampling efficiency with three-section (350/350/350 mg) Anasorb CSC showing the best results. Therefore, air samples were collected using two 3-section Anasorb CSC sorbent tubes in series at 0.02 L/min for up to 8 hr for sample volumes of up to 9.6 L. The sorbent tubes were extracted in methylene chloride, and analyzed by gas chromatography with flame ionization detection. The method was validated from 0.1× to 20× the target level of 0.5 ppm (2.3 mg/m(3)) for a 9.6 L air volume. Desorption efficiencies for HFO-1234yf were 88 to 109% for all replicates over the validation range with a mean overall recovery of 93%. Simulated sampling efficiencies ranged from 87 to 104% with a mean of 94%. No migration or breakthrough to the back tube was observed under the sampling conditions evaluated. HFO-1234yf samples showed acceptable storage stability on Anasorb CSC sorbent up to a period of 30 days when stored under ambient, refrigerated, or frozen temperature conditions.

  1. Quantitative Analysis of Mixed Halogen Dioxins and Furans in Fire Debris Utilizing Atmospheric Pressure Ionization Gas Chromatography-Triple Quadrupole Mass Spectrometry.

    PubMed

    Organtini, Kari L; Myers, Anne L; Jobst, Karl J; Reiner, Eric J; Ross, Brian; Ladak, Adam; Mullin, Lauren; Stevens, Douglas; Dorman, Frank L

    2015-10-20

    Residential and commercial fires generate a complex mixture of volatile, semivolatile, and nonvolatile compounds. This study focused on the semi/nonvolatile components of fire debris to better understand firefighter exposure risks. Using the enhanced sensitivity of gas chromatography coupled to atmospheric pressure ionization-tandem mass spectrometry (APGC-MS/MS), complex fire debris samples collected from simulation fires were analyzed for the presence of potentially toxic polyhalogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs and PBDD/Fs). Extensive method development was performed to create multiple reaction monitoring (MRM) methods for a wide range of PXDD/Fs from dihalogenated through hexa-halogenated homologue groups. Higher halogenated compounds were not observed due to difficulty eluting them off the long column used for analysis. This methodology was able to identify both polyhalogenated (mixed bromo-/chloro- and polybromo-) dibenzo-p-dioxins and dibenzofurans in the simulated burn study samples collected, with the dibenzofuran species being the dominant compounds in the samples. Levels of these compounds were quantified as total homologue groups due to the limitations of commercial congener availability. Concentration ranges in household simulation debris were observed at 0.01-5.32 ppb (PXDFs) and 0.18-82.11 ppb (PBDFs). Concentration ranges in electronics simulation debris were observed at 0.10-175.26 ppb (PXDFs) and 0.33-9254.41 ppb (PBDFs). Samples taken from the particulate matter coating the firefighters' helmets contained some of the highest levels of dibenzofurans, ranging from 4.10 ppb to 2.35 ppm. The data suggest that firefighters and first responders at fire scenes are exposed to a complex mixture of potentially hundreds to thousands of different polyhalogenated dibenzo-p-dioxins and dibenzofurans that could negatively impact their health.

  2. Gas chromatography/atmospheric pressure chemical ionization/mass spectrometry for the analysis of organochlorine pesticides and polychlorinated biphenyls in human serum.

    PubMed

    Geng, Dawei; Jogsten, Ingrid Ericson; Dunstan, Jody; Hagberg, Jessika; Wang, Thanh; Ruzzin, Jerome; Rabasa-Lhoret, Rémi; van Bavel, Bert

    2016-07-01

    A method using a novel atmospheric pressure chemical ionization source for coupling gas chromatography (GC/APCI) to triple quadrupole mass spectrometry (MS/MS) for the determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) regulated by the Stockholm Convention is presented. One microliter injection of a six-point calibration curve of native PCBs and OCPs, ranging from 0.04 to 300pg/μL, was performed. The relative standard deviation (RSD) of the relative response factors (RRFs) was less than 15% with a coefficient of determination (r(2))>0.995. Meanwhile, two calibration solutions (CS), CS 2 (0.4pg/μL) and CS 3 (4pg/μL) were analyzed to study the repeatability calculated for both area and RRFs. The RSD for RRF ranged from 3.1 to 16% and 3.6 to 5.5% for CS 2 and CS 3, respectively. The limits of detection (LOD) determined by peak-to-peak signal-to-noise ratio (S/N) of 3 were compared between the GC/APCI/MS/MS and a GC coupled to high resolution mass spectrometry (GC/HRMS) system. GC/APCI/MS/MS resulted in lower LOD for most of the compounds, except for PCB#74, cis-chlordane and trans-chlordane. GC/APCI/MS/MS and GC/HRMS were also compared by performing analysis on 75 human serum samples together with eight QA/QC serum samples. The comparison between GC/APCI/MS/MS system and GC/HRMS system for 16 of the targeted compounds was carried out. No statistically significant difference was discovered. Due to increased sensitivity and user friendly operation under atmospheric pressure, GC/APCI/MS/MS is a powerful alternative technique that can easily meet the specification of GC/HRMS.

  3. Identification and quantification of seven volatile n-nitrosamines in cosmetics using gas chromatography/chemical ionization-mass spectrometry coupled with head space-solid phase microextraction.

    PubMed

    Choi, Na Rae; Kim, Yong Pyo; Ji, Won Hyun; Hwang, Geum-Sook; Ahn, Yun Gyong

    2016-01-01

    An analytical method was developed for the identification and quantification of seven volatile n-nitrosamines (n-nitrosodimethylamine [NDMA], n-nitrosoethylmethylamine [NMEA], n-nitrosodiethylamine [NDEA], n-nitrosodipropylamine [NDPA], n-nitrosodibutylamine [NDBA], n-nitrosopiperidine [NPIP], and n-nitrosopyrrolidine [NPYR]) in water insoluble cream type cosmetics. It was found that the head space-solid phase microextraction (HS-SPME) was suitable for extraction, clean up, and pre-concentration of n-nitrosamines in the cream type samples so its optimal conditions were investigated. Identification and quantification of n-nitrosamines using single quadrupole gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode were carried out with accurate mass measurements. Their accurate masses of protonated molecular ions were obtained within 10 mDa of the theoretical masses when sufficiently high signal was acquired from the unique calibration method using mass and isotope accuracy. For the method validation of quantification, spiking experiments were carried out to determine the linearity, recovery, and method detection limit (MDL) using three deuterated internal standards. The average recovery was 79% within 20% relative standard deviation (RSD) at the concentration of 50 ng/g. MDLs ranged from 0.46 ng/g to 36.54 ng/g, which was satisfactory for the directive limit of 50 ng/g proposed by the European Commission (EC). As a result, it was concluded that the method could be provided for the accurate mass screening, confirmation, and quantification of n-nitrosamines when applied to cosmetic inspection.

  4. Partial least squares analysis of rocket propulsion fuel data using diaphragm valve-based comprehensive two-dimensional gas chromatography coupled with flame ionization detection.

    PubMed

    Freye, Chris E; Fitz, Brian D; Billingsley, Matthew C; Synovec, Robert E

    2016-06-01

    The chemical composition and several physical properties of RP-1 fuels were studied using comprehensive two-dimensional (2D) gas chromatography (GC×GC) coupled with flame ionization detection (FID). A "reversed column" GC×GC configuration was implemented with a RTX-wax column on the first dimension ((1)D), and a RTX-1 as the second dimension ((2)D). Modulation was achieved using a high temperature diaphragm valve mounted directly in the oven. Using leave-one-out cross-validation (LOOCV), the summed GC×GC-FID signal of three compound-class selective 2D regions (alkanes, cycloalkanes, and aromatics) was regressed against previously measured ASTM derived values for these compound classes, yielding root mean square errors of cross validation (RMSECV) of 0.855, 0.734, and 0.530mass%, respectively. For comparison, using partial least squares (PLS) analysis with LOOCV, the GC×GC-FID signal of the entire 2D separations was regressed against the same ASTM values, yielding a linear trend for the three compound classes (alkanes, cycloalkanes, and aromatics), yielding RMSECV values of 1.52, 2.76, and 0.945 mass%, respectively. Additionally, a more detailed PLS analysis was undertaken of the compounds classes (n-alkanes, iso-alkanes, mono-, di-, and tri-cycloalkanes, and aromatics), and of physical properties previously determined by ASTM methods (such as net heat of combustion, hydrogen content, density, kinematic viscosity, sustained boiling temperature and vapor rise temperature). Results from these PLS studies using the relatively simple to use and inexpensive GC×GC-FID instrumental platform are compared to previously reported results using the GC×GC-TOFMS instrumental platform. PMID:27130110

  5. Determination of valproic acid in human plasma using dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection

    PubMed Central

    Fazeli-Bakhtiyari, Rana; Panahi-Azar, Vahid; Sorouraddin, Mohammad Hossein; Jouyban, Abolghasem

    2015-01-01

    Objective(s): Dispersive liquid-liquid microextraction coupled with gas chromatography (GC)-flame ionization detector was developed for the determination of valproic acid (VPA) in human plasma. Materials and Methods: Using a syringe, a mixture of suitable extraction solvent (40 µl chloroform) and disperser (1 ml acetone) was quickly added to 10 ml of diluted plasma sample containing VPA (pH, 1.0; concentration of NaCl, 4% (w/v)), resulting in a cloudy solution. After centrifugation (6000 rpm for 6 min), an aliquot (1 µl) of the sedimented organic phase was removed using a 1-µl GC microsyringe and injected into the GC system for analysis. One variable at a time optimization method was used to study various parameters affecting the extraction efficiency of target analyte. Then, the developed method was fully validated for its accuracy, precision, recovery, stability, and robustness. Results: Under the optimum extraction conditions, good linearity range was obtained for the calibration graph, with correlation coefficient higher than 0.998. Limit of detection and lower limit of quantitation were 3.2 and 6 μg/ml, respectively. The relative standard deviations of intra and inter-day analysis of examined compound were less than 11.5%. The relative recoveries were found in the range of 97 to 107.5%. Finally, the validated method was successfully applied to the analysis of VPA in patient sample. Conclusion: The presented method has acceptable levels of precision, accuracy and relative recovery and could be used for therapeutic drug monitoring of VPA in human plasma. PMID:26730332

  6. Direct determination of acrylamide in potato chips by using headspace solid-phase microextraction coupled with gas chromatography-flame ionization detection.

    PubMed

    Ghiasvand, Ali Reza; Hajipour, Somayeh

    2016-01-01

    Acrylamide is a potentially toxic and carcinogenic substance present in many high-consumption foods. Recently, this matter has been placed in category of "reasonably anticipated to be a human carcinogen" by National Toxicology Program (NTP). Therefore, simple and cost-effective determination of acrylamide in food samples has attracted intense interest. The most reported techniques for this purpose are GC-MS and LC-MS, which are very expensive and available in few laboratories. In this research, for the first time, a rapid, easy and low-cost method is introduced for sensitive and precise determination of acrylamide in foodstuffs, using gas chromatography-flame ionization detection (GC-FID) system after its direct trapping in the upper atmosphere of samples by headspace solid-phase microextraction (HS-SPME). The effects of main experimental variables were studied and the optimized parameters were obtained as the type of fiber, carboxen/divinylbenzene/polydimethylsiloxane (CAR/DVB/PDMS); extraction time, 30 min; extraction temperature, 60°C; moisture content, 10 µL water per 1g of sample; desorption time, 2 min; and desorption temperature, 230°C. The linear calibration graph was obtained in the range of 0.77-50 µg g(-1), with regression coefficient of 0.998. The detection and quantification limits of the proposed method were 0.22 and 0.77 µg g(-1), respectively. The recoveries, for different food samples, were 79.6-95.7%. The repeatability of measurements, expressed as relative standard deviation (RSD), were found to be 4.1-8.0% (n=9). The proposed HS-SPME-GC-FID method was successfully carried out for quantifying of trace levels of acrylamide in some processed food products (chips and French fries), sold in open local markets. PMID:26695284

  7. Identification and quantification of seven volatile n-nitrosamines in cosmetics using gas chromatography/chemical ionization-mass spectrometry coupled with head space-solid phase microextraction.

    PubMed

    Choi, Na Rae; Kim, Yong Pyo; Ji, Won Hyun; Hwang, Geum-Sook; Ahn, Yun Gyong

    2016-01-01

    An analytical method was developed for the identification and quantification of seven volatile n-nitrosamines (n-nitrosodimethylamine [NDMA], n-nitrosoethylmethylamine [NMEA], n-nitrosodiethylamine [NDEA], n-nitrosodipropylamine [NDPA], n-nitrosodibutylamine [NDBA], n-nitrosopiperidine [NPIP], and n-nitrosopyrrolidine [NPYR]) in water insoluble cream type cosmetics. It was found that the head space-solid phase microextraction (HS-SPME) was suitable for extraction, clean up, and pre-concentration of n-nitrosamines in the cream type samples so its optimal conditions were investigated. Identification and quantification of n-nitrosamines using single quadrupole gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode were carried out with accurate mass measurements. Their accurate masses of protonated molecular ions were obtained within 10 mDa of the theoretical masses when sufficiently high signal was acquired from the unique calibration method using mass and isotope accuracy. For the method validation of quantification, spiking experiments were carried out to determine the linearity, recovery, and method detection limit (MDL) using three deuterated internal standards. The average recovery was 79% within 20% relative standard deviation (RSD) at the concentration of 50 ng/g. MDLs ranged from 0.46 ng/g to 36.54 ng/g, which was satisfactory for the directive limit of 50 ng/g proposed by the European Commission (EC). As a result, it was concluded that the method could be provided for the accurate mass screening, confirmation, and quantification of n-nitrosamines when applied to cosmetic inspection. PMID:26653425

  8. Direct determination of acrylamide in potato chips by using headspace solid-phase microextraction coupled with gas chromatography-flame ionization detection.

    PubMed

    Ghiasvand, Ali Reza; Hajipour, Somayeh

    2016-01-01

    Acrylamide is a potentially toxic and carcinogenic substance present in many high-consumption foods. Recently, this matter has been placed in category of "reasonably anticipated to be a human carcinogen" by National Toxicology Program (NTP). Therefore, simple and cost-effective determination of acrylamide in food samples has attracted intense interest. The most reported techniques for this purpose are GC-MS and LC-MS, which are very expensive and available in few laboratories. In this research, for the first time, a rapid, easy and low-cost method is introduced for sensitive and precise determination of acrylamide in foodstuffs, using gas chromatography-flame ionization detection (GC-FID) system after its direct trapping in the upper atmosphere of samples by headspace solid-phase microextraction (HS-SPME). The effects of main experimental variables were studied and the optimized parameters were obtained as the type of fiber, carboxen/divinylbenzene/polydimethylsiloxane (CAR/DVB/PDMS); extraction time, 30 min; extraction temperature, 60°C; moisture content, 10 µL water per 1g of sample; desorption time, 2 min; and desorption temperature, 230°C. The linear calibration graph was obtained in the range of 0.77-50 µg g(-1), with regression coefficient of 0.998. The detection and quantification limits of the proposed method were 0.22 and 0.77 µg g(-1), respectively. The recoveries, for different food samples, were 79.6-95.7%. The repeatability of measurements, expressed as relative standard deviation (RSD), were found to be 4.1-8.0% (n=9). The proposed HS-SPME-GC-FID method was successfully carried out for quantifying of trace levels of acrylamide in some processed food products (chips and French fries), sold in open local markets.

  9. Systems and methods for cylindrical hall thrusters with independently controllable ionization and acceleration stages

    DOEpatents

    Diamant, Kevin David; Raitses, Yevgeny; Fisch, Nathaniel Joseph

    2014-05-13

    Systems and methods may be provided for cylindrical Hall thrusters with independently controllable ionization and acceleration stages. The systems and methods may include a cylindrical channel having a center axial direction, a gas inlet for directing ionizable gas to an ionization section of the cylindrical channel, an ionization device that ionizes at least a portion of the ionizable gas within the ionization section to generate ionized gas, and an acceleration device distinct from the ionization device. The acceleration device may provide an axial electric field for an acceleration section of the cylindrical channel to accelerate the ionized gas through the acceleration section, where the axial electric field has an axial direction in relation to the center axial direction. The ionization section and the acceleration section of the cylindrical channel may be substantially non-overlapping.

  10. 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

  11. Kinetic-Hydrodynamic Models of the Solar Wind Interaction with the Partially Ionized Supersonic Flow of the Local Interstellar Gas: Predictions and Interpretations of the Experimental Data

    NASA Astrophysics Data System (ADS)

    Baranov, Vladimir B.

    2009-02-01

    At present there is no doubt that the local interstellar medium (LISM) is mainly partially ionized hydrogen gas moving with a supersonic flow relative to the solar system. The bulk velocity of this flow is approximately equal ˜26 km/s. Although the interaction of the solar wind with the charged component (below plasma component) of the LISM can be described in the framework of hydrodynamic approach, the interaction of H atoms with the plasma component can be correctly described only in the framework of kinetic theory because the mean free path of H atoms in the main process of the resonance charge exchange is comparable with a characteristic length of the problem considered. Results of self-consistent, kinetic-hydrodynamic models are considered in this review paper. First, such the model was constructed by Baranov and Malama (J. Geophys. Res. 98(A9):15,157-15,163, 1993). Up to now it is mainly developed by Moscow group taking into account new experimental data obtained onboard spacecraft studying outer regions of the solar system (Voyager 1 and 2, Pioneer 10 and 11, Hubble Space Telescope, Ulysses, SOHO and so on). Predictions and interpretations of experimental data obtained on the basis of these models are presented. Kinetic models for describing H atom motion were later suggested by Fahr et al. (Astron. Astrophys 298:587-600, 1995) and Lipatov et al. (J. Geophys. Res. 103(A9):20,631-20,642, 1998). However they were not self-consistent and did not incorporate sources to the plasma component. A self-consistent kinetic-hydrodynamic model suggested by Heerikhuisen et al. (J. Geophys. Res. 111:A06110, 2006, Astrophys. J. 655:L53-L56, 2007) was not tested on the results by Baranov and Malama (J. Geophys. Res. 111:A06110, 1993) although it was suggested much later. Besides authors did not describe in details their Monte Carlo method for a solution of the H atom Boltzmann equation and did not inform about an accuracy of this method. Therefore the results of

  12. Miniature Oxidizer Ionizer for a Fuel Cell

    NASA Technical Reports Server (NTRS)

    Hartley, Frank

    2006-01-01

    A proposed miniature device for ionizing the oxygen (or other oxidizing gas) in a fuel cell would consist mostly of a membrane ionizer using the same principles as those of the device described in the earlier article, Miniature Bipolar Electrostatic Ion Thruster (NPO-21057). The oxidizing gas would be completely ionized upon passage through the holes in the membrane ionizer. The resulting positively charged atoms or molecules of oxidizing gas could then, under the influence of the fringe fields of the ionizer, move toward the fuel-cell cathode that would be part of a membrane/electrode assembly comprising the cathode, a solid-electrolyte membrane, and an anode. The electro-oxidized state of the oxidizer atoms and molecules would enhance transfer of them through the cathode, thereby reducing the partial pressure of the oxidizer gas between the ionizer and the fuel-cell cathode, thereby, in turn, causing further inflow of oxidizer gas through the holes in the membrane ionizer. Optionally the ionizer could be maintained at a positive electric potential with respect to the cathode, in which case the resulting electric field would accelerate the ions toward the cathode.

  13. Optical ionization detector

    DOEpatents

    Wuest, C.R.; Lowry, M.E.

    1994-03-29

    An optical ionization detector wherein a beam of light is split so that one arm passes through a fiber optics and the other arm passes through a gas-filled region, and uses interferometry to detect density changes in a gas when charged particles pass through it. The gas-filled region of the detector is subjected to a high electric field and as a charged particle traverses this gas region electrons are freed from the cathode and accelerated so as to generate an electron avalanche which is collected on the anode. The gas density is effected by the electron avalanche formation and if the index or refraction is proportional to the gas density the index will change accordingly. The detector uses this index change by modulating the one arm of the split light beam passing through the gas, with respect to the other arm that is passed through the fiber optic. Upon recombining of the beams, interference fringe changes as a function of the index change indicates the passage of charged particles through the gaseous medium. 3 figures.

  14. Optical ionization detector

    DOEpatents

    Wuest, Craig R.; Lowry, Mark E.

    1994-01-01

    An optical ionization detector wherein a beam of light is split so that one arm passes through a fiber optics and the other arm passes through a gas-filled region, and uses interferometry to detect density changes in a gas when charged particles pass through it. The gas-filled region of the detector is subjected to a high electric field and as a charged particle traverses this gas region electrons are freed from the cathode and accelerated so as to generate an electron avalanche which is collected on the anode. The gas density is effected by the electron avalanche formation and if the index or refraction is proportional to the gas density the index will change accordingly. The detector uses this index change by modulating the one arm of the split light beam passing through the gas, with respect to the other arm that is passed through the fiber optic. Upon recombining of the beams, interference fringe changes as a function of the index change indicates the passage of charged particles through the gaseous medium.

  15. GAS IONIZING AND COMPRESSING DEVICE

    DOEpatents

    Little, E.M.; Thomson, D.B.; Josephson, V.; Scott, F.R.

    1961-08-22

    A device is described for producing high energy gaseous plasmas. The device consists of a unitary refractory vessel having tapered end portions, a cylindrical middle portion, and means for spontaneously generating oppositely propelled plasma masses from the tapered end portions to a collision zone in the cylindrical middle portion. The means come from the spontaneous generation of diverging magnetic fields in the end portions and an axial magnetic field in the cylindrical portion. (AEC)

  16. Fingerprinting and source identification of an oil spill in China Bohai Sea by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry coupled with multi-statistical analyses.

    PubMed

    Sun, Peiyan; Bao, Mutai; Li, Guangmei; Wang, Xinping; Zhao, Yuhui; Zhou, Qing; Cao, Lixin

    2009-01-30

    This paper describes a case study in which advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical composition and determine the source of an unknown spilled oil reported on the beach of China Bohai Sea in 2005. The spilled oil was suspected to be released from nearby platforms. In response to this specific site investigation need, a tiered analytical approach using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID) was applied. A variety of diagnostic ratios of "source-specific marker" compounds, in particular isomers of biomarkers, were determined and compared. Several statistical data correlation analysis methods were applied, including clustering analysis and Student's t-test method. The comparison of the two methods was conducted. The comprehensive analysis results reveal the following: (1) The oil fingerprinting of three spilled oil samples (S1, S2 and S3) positively match each other; (2) The three spilled oil samples have suffered different weathering, dominated by evaporation with decrease of the low-molecular-mass n-alkanes at different degrees; (3) The oil fingerprinting profiles of the three spilled oil samples are positive match with that of the suspected source oil samples C41, C42, C43, C44 and C45; (4) There are significant differences in the oil fingerprinting profiles between the three spilled oil samples and the suspected source oil samples A1, B1, B2, B3, B4, C1, C2, C3, C5 and C6.

  17. Novel analytical approach for brominated flame retardants based on the use of gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry with emphasis in highly brominated congeners.

    PubMed

    Portolés, Tania; Sales, Carlos; Gómara, Belén; Sancho, Juan Vicente; Beltrán, Joaquim; Herrero, Laura; González, María José; Hernández, Félix

    2015-10-01

    The analysis of brominated flame retardants (BFRs) commonly relies on the use of gas chromatography coupled to mass spectrometry (GC-MS) operating in electron ionization (EI) and electron capture negative ionization (ECNI) modes using quadrupole, triple quadrupole, ion trap, and magnetic sector analyzers. However, these brominated contaminants are examples of compounds for which a soft and robust ionization technique might be favorable since they show high fragmentation in EI and low specificity in ECNI. In addition, the low limits of quantification (0.01 ng/g) required by European Commission Recommendation 2014/118/EU on the monitoring of traces of BFRs in food put stress on the use of highly sensitive techniques/methods. In this work, a new approach for the extremely sensitive determination of BFRs taking profit of the potential of atmospheric pressure chemical ionization (APCI) combined with GC and triple quadrupole (QqQ) mass analyzer is proposed. The objective was to explore the potential of this approach for the BFRs determination in samples at pg/g levels, taking marine samples and a cream sample as a model. Ionization and fragmentation behavior of 14 PBDEs (congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two novel BFRs, decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), in the GC-APCI-MS system has been investigated. The formation of highly abundant (quasi) molecular ion was the main advantage observed in relation to EI. Thus, a notable improvement in sensitivity and specificity was observed when using it as precursor ion in tandem MS. The improved detectability (LODs < 10 fg) achieved when using APCI compared to EI has been demonstrated, which is especially relevant for highly brominated congeners. Analysis of samples from an intercomparison exercise and samples from the marine field showed the potential of this approach for the reliable identification and quantification at very low

  18. Novel analytical approach for brominated flame retardants based on the use of gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry with emphasis in highly brominated congeners.

    PubMed

    Portolés, Tania; Sales, Carlos; Gómara, Belén; Sancho, Juan Vicente; Beltrán, Joaquim; Herrero, Laura; González, María José; Hernández, Félix

    2015-10-01

    The analysis of brominated flame retardants (BFRs) commonly relies on the use of gas chromatography coupled to mass spectrometry (GC-MS) operating in electron ionization (EI) and electron capture negative ionization (ECNI) modes using quadrupole, triple quadrupole, ion trap, and magnetic sector analyzers. However, these brominated contaminants are examples of compounds for which a soft and robust ionization technique might be favorable since they show high fragmentation in EI and low specificity in ECNI. In addition, the low limits of quantification (0.01 ng/g) required by European Commission Recommendation 2014/118/EU on the monitoring of traces of BFRs in food put stress on the use of highly sensitive techniques/methods. In this work, a new approach for the extremely sensitive determination of BFRs taking profit of the potential of atmospheric pressure chemical ionization (APCI) combined with GC and triple quadrupole (QqQ) mass analyzer is proposed. The objective was to explore the potential of this approach for the BFRs determination in samples at pg/g levels, taking marine samples and a cream sample as a model. Ionization and fragmentation behavior of 14 PBDEs (congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two novel BFRs, decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), in the GC-APCI-MS system has been investigated. The formation of highly abundant (quasi) molecular ion was the main advantage observed in relation to EI. Thus, a notable improvement in sensitivity and specificity was observed when using it as precursor ion in tandem MS. The improved detectability (LODs < 10 fg) achieved when using APCI compared to EI has been demonstrated, which is especially relevant for highly brominated congeners. Analysis of samples from an intercomparison exercise and samples from the marine field showed the potential of this approach for the reliable identification and quantification at very low

  19. Detailed gas and diesel vehicle emissions: PTR-MS measurements of real-time VOC profiles and comprehensive characterization of primary emissions for IVOC, SVOC, and LVOC by gas chromatography with vacuum ultra-violet ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Drozd, G.; Frodin, B.; Zhao, Y.; Franklin, J. P.; Cross, E. S.; Saleh, R.; Saliba, G.; Lambe, A. T.; Sardar, S.; Maldonado, H.; Russell, L. M.; Kroll, J. H.; Robinson, A. L.; Goldstein, A. H.

    2015-12-01

    Over the past fifteen years US vehicle emissions standards have dramatically improved, with the goal of reducing urban air pollution. Recent studies demonstrate secondary organic aerosol (SOA) to be the dominant contributor to urban organic aerosol, but controversy remains regarding the contributions of different vehicle types to SOA. Increased potency for SOA formation from non methane hydrocarbons (NMHC) from newer vehicles that meet tighter emission standards has also been observed. Both speciation and temporal resolution of vehicular emissions are critical for predicting SOA formation. The relative importance of diesel and gasoline emissions to SOA formation depends critically on speciation. Experiments were conducted at the California Air Resources Board Haagen-Smit Laboratory to better understand SOA formation for low, ultra-low, super ultra-low and partial zero emission vehicles (LEV, ULEV, SULEV, PZEV). Exhaust was sampled on filters and adsorbent tubes to measure intermediate-, semi-, and low-volatility NMHC (IVOC, SVOC, LVOC). A proton-transfer-reaction mass spectrometer (PTR-MS) measured volatile organics (VOC) emissions with high time-resolution. Analysis of filters and adsorbent tubes using gas chromatography with vacuum-ultra-violet ionization mass spectrometry provided unprecedented characterization of emissions according to degree of branching, number of cyclic rings, aromaticity, and molecular weight. ULEV vehicles show the composition distributions of primary particulate emissions peak for compounds in the SVOC range. PZEV vehicle emissions peak in the IVOC range. Diesel vehicles have up to ten times higher emissions than gasoline vehicles; their distributions have significant IVOC levels and peak in the SVOC/LVOC range. Our measurements are used to predict potential SOA formation by vehicle standard class and the relative SOA formation for diesel and gasoline vehicles. PTR-MS measurement show VOC emissions after cold start occur almost entirely

  20. Two suicidal fatalities due to the ingestion of chlorfenvinphos formulations: simultaneous determination of the pesticide and the petroleum distillates in tissues by gas chromatography-flame-ionization detection and gas chromatography-mass spectrometry.

    PubMed

    Martínez, María A; Ballesteros, Salomé

    2012-01-01

    Chlorfenvinphos (CFVP) is an organophosporus insecticide designated as a threat agent by the National Institutes of Health (NIH). However, there are very few reported cases of poisonings in humans and none with postmortem toxicological analysis. We report the first two fatalities due to suicidal massive ingestion of a veterinary formulation containing CFVP and petroleum distillates. Case 1: A 24-year-old woman was found dead by her mother. According to the police records, the room was filled with an odor of solvents or pesticides and feces. There was an empty bottle of Supona(®) near the body and a suicide note on a Bible on a table. The only relevant postmortem finding was that the lungs appeared congested and edematous. Case 2: A 60-year-old man committed in his van by ingesting an unknown product. The vehicle was locked and had an odor that resembled an acid, sulfate, or solvent according to different witnesses. There was a suicide note as well as multiple containers containing automobile products nearby. The stomach of the victim was filled with abundant pale greenish fluid with a similar odor to that presented in the vehicle. The simultaneous toxicological screening and quantitation of CFVP and petroleum distillates [a mixture of trimethylbenzene isomers (TMBs)] was performed by means of gas chromatography with flame-ionization detection (GC-FID) and confirmation was performed using gas chromatography-mass spectrometry (GC-MS). Disposition of CFVP and TMBs in different tissues were, respectively, as follows: Case 1: heart blood, 8.6 and 3.7 mg/L; liver, 60.0 and 33.4 mg/kg; and stomach contents, 1132 mg/L (792.4 mg total) and 377.0 mg/L (263.9 mg total). Case 2: heart blood, 4.4 and 6.5 mg/L; urine, 1.4 and detected (< LOQ); bile 7.8 and 12.2 mg/L; vitreous 0.3 mg/L and detected (< LOQ); liver, 139.2 and 172.1 mg/kg; and stomach contents, 76,168 mg/L (72,359 mg total) and 108,109 mg/L (102,703 mg total). Results of alcohol, other volatiles, abused and

  1. Quantitation of cocaine, benzoylecgonine, cocaethylene, methylecgonine, and norcocaine in human hair by positive ion chemical ionization (PICI) gas chromatography-tandem mass spectrometry.

    PubMed

    Bourland, J A; Hayes, E F; Kelly, R C; Sweeney, S A; Hatab, M M

    2000-10-01

    A total of 30 human head-hair samples were analyzed for cocaine (COC), cocaethylene (CE), benzoylecgonine (BE), methylecgonine (EME), and norcocaine (NCOC) using a sensitive positive ion chemical ionization gas chromatography-tandem mass spectrometry (GC-MS-MS) method. All 30 hair samples had been previously submitted to the laboratory and had confirmed positive for cocaine. Hair samples (20 mg each) were cut into small segments (2-5 mm) and incubated overnight at 45 degrees C in 0.1 N HCl after the addition of 50 microL of an internal standard mix of COC-d3 (1.0 ng/mg), BE-d3 (0.5 ng/mg), EME-d3 (0.25 ng/mg), and NCOC-d3 (0.25 ng/mg). The samples were then extracted with Clean Screen extraction columns from United Chemical Technologies, Inc. The final extract was evaporated to dryness and derivatized with 50 microL of 1,1,1,3,3,3-hexafluoro-2-propanol and 50 microL of trifluoroacetic anhydride at 90 degrees C for 15 min. The derivatized samples were allowed to cool to room temperature, evaporated to dryness, and then reconstituted in 50 microL of ethyl acetate. Parent set masses (unbolded ions) and product ions were m/z 304 and m/z 182 and 82 (COC), m/z 307 and m/z 185 and 85 (COC-d3), m/z 318 and m/z 196 and 82 (CE), m/z 440 and m/z 318 and 105 (BE), m/z 443 and m/z 321 and 105 (BE-d3), m/z 296 and m/z 182, and 82 (EME), m/z 299 and m/z 185 and 85 (EME-d3), m/z 403 and m/z 386 and 105 (NCOC), m/z 406 and m/z 389 and 105 (NCOC-d3). Quantitation was accomplished by calculating the area ratio of the higher mass product ion (underlined ions) of analyte to the respective internal standard based on multilevel calibrations from 0.01 to 10.0 ng/mg. The GC-MS-MS method had a limit of detection of 0.01 ng/mg and a limit of quantitation of 0.05 ng/mg for all five analytes. COC, BE, and EME were detected in all 30 samples, and CE and NCOC were found in 19 and 29 samples, respectively. The average relative percentages of each metabolite normalized to the cocaine

  2. A multi-residue method for pesticides analysis in green coffee beans using gas chromatography-negative chemical ionization mass spectrometry in selective ion monitoring mode.

    PubMed

    Pizzutti, Ionara R; de Kok, Andre; Dickow Cardoso, Carmem; Reichert, Bárbara; de Kroon, Marijke; Wind, Wouter; Weber Righi, Laís; Caiel da Silva, Rosselei

    2012-08-17

    In this study, a new gas chromatography-mass spectrometry (GC-MS) method, using the very selective negative chemical ionization (NCI) mode, was developed and applied in combination with a modified acetonitrile-based extraction method (QuEChERS) for the analysis of a large number of pesticide residues (51 pesticides, including isomers and degradation products) in green coffee beans. A previously developed integrated sample homogenization and extraction method for both pesticides and mycotoxins analysis was used. An homogeneous slurry of green milled coffee beans and water (ratio 1:4, w/w) was prepared and extracted with acetonitrile/acetic acid (1%), followed by magnesium sulfate addition for phase separation. Aliquots from this extract could be used directly for LC-MS/MS analysis of mycotoxins and LC-amenable pesticides. For GC-MS analysis, a further clean-up was necessary. C18- and PSA-bonded silica were tested as dispersive solid-phase extraction (d-SPE) sorbents, separate and as a mixture, and the best results were obtained using C18-bonded silica. For the optimal sensitivity and selectivity, GC-MS detection in the NCI-selected ion monitoring (SIM) mode had to be used to allow the fast analysis of the difficult coffee bean matrix. The validation was performed by analyzing recovery samples at three different spike concentrations, 10, 20 and 50 μg kg(-1), with 6 replicates (n=6) at each concentration. Linearity (r(2)) of calibration curves, estimated instrument and method limits of detection and limits of quantification (LOD(i), LOD(m), LOQ(i) and LOQ(m), respectively), accuracy (as recovery %), precision (as RSD%) and matrix effects (%) were determined for each individual pesticide. From the 51 analytes (42 parent pesticides, 4 isomers and 5 degradation products) determined by GC-MS (NCI-SIM), approximately 76% showed average recoveries between 70-120% and 75% and RSD ≤ 20% at the lowest spike concentration of 10 μg kg(-1), the target method LOQ. For the

  3. beta-Cyclodextrin-bonded silica particles as the solid-phase extraction medium for the determination of phenol compounds in water samples followed by gas chromatography with flame ionization and mass spectrometry detection.

    PubMed

    Faraji, Hakim

    2005-09-16

    A new absorbent for solid-phase extraction (SPE) was prepared by a beta-cyclodextrin bonded silica stationary phase (CDS) has been applied to determine the concentrations of phenol compounds in water samples. SPE of selected phenolic compounds from aqueous samples were performed using 250 mg CDS. The determination was subsequently carried out by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Compared with available SPE, the CDS showed high sensitivity and fast velocity of mass transfer for phenolic compound because of its porous structure of beta-cyclodextrin. The relative standard deviation (RSD) for river water sample spiked with phenolic compounds at sub-ppb level was lower than 10% and limit of detection (LOD) for these compounds were between 10 and 100 ng l(-1). PMID:16130725

  4. Atmospheric and ionospheric response to trace gas perturbations through the ice age to the next century in the middle atmosphere. Part II-ionization

    NASA Astrophysics Data System (ADS)

    Beig, G.; Mitra, A. P.

    1997-07-01

    A global two-dimensional meridional ion composition model of the middle atmosphere is used to examine the effect of changing concentrations of several greenhouse gases on the overall distribution of ionization for this region, along with a steady state calculation for the upper heights. Changes in the neutral parameters for this study are taken from the companion article (Beig and Mitra, 1997). It has been predicted that there are several sensitive signals of man-made perturbations in the middle atmospheric ionization. In the mesospheric region, for a doubled CO2 scenario, we find that the total ionization density does not change appreciably and the maximum variation is found to be around 15% at about 70 km. However, the distribution of individual ions shows a considerable variation (up to about 100%) throughout the middle atmosphere. The fall-off height of the fractional abundance of water cluster ions is higher for 2050 A.D., suggesting domination of these ions up to greater heights. The concentration of water cluster ions increases below about 85 km; above this height it starts to decrease sharply with height. When a scenario with doubled CO2, with CH4 and business-as-usual (BAU) (for CFCs and N2O) is considered in the stratospheric region, it is found that only one family of negative ions, called NO3-core ions, is dominant instead of two in the normal case. Simulations are also made through the ages since the last ice age. Results indicate a reverse trend as compared to the above.

  5. Characterization of low-molecular weight iodine-terminated polyethylenes by gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with the use of derivatization.

    PubMed

    Zaikin, Vladimir G; Borisov, Roman S; Polovkov, Nikolai Yu; Zhilyaev, Dmitry I; Vinogradov, Aleksei A; Ivanyuk, Aleksei V

    2013-01-01

    Gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry, in conjunction with various derivatization approaches, have been applied to structure determination of individual oligomers and molecular-mass distributions (MMD) in low-molecular mass polyethylene having an iodine terminus. Direct GC/MS analysis has shown that the samples under investigation composed of polyethyelene-iodides (major components) and n-alkanes. Exchange reaction with methanol in the presence of NaOH gave rise to methoxy-derivatives and n-alkenes. Electron ionization mass spectra have shown that the former contained terminal methoxy groups indicating the terminal position of the iodine atom in the initial oligomers. MMD parameters have been determined with the aid of MALDI mass spectrometry followed by preliminary derivatization-formation of covalently bonded charge through the reaction of iodides with triphenylphosphine, trialkylamines, pyridine or quinoline. The mass spectra revealed well-resolved peaks for cationic parts of derivatized oligomers allowing the determination of MMD. The latter values have been compared with those calculated from GC/MS data.

  6. GAS-PHASE SYNTHESIS OF PRECURSORS OF INTERSTELLAR GLYCINE: A COMPUTATIONAL STUDY OF THE REACTIONS OF ACETIC ACID WITH HYDROXYLAMINE AND ITS IONIZED AND PROTONATED DERIVATIVES

    SciTech Connect

    Barrientos, Carmen; Redondo, Pilar; Largo, Laura; Rayon, Victor M.; Largo, Antonio

    2012-04-01

    A computational study of the reactions of hydroxylamine and its ionized and protonated derivatives with acetic acid is provided. The reaction of neutral hydroxylamine with acetic acid, despite being clearly exothermic, involves a very large energy barrier. The reaction of ionized hydroxylamine with acetic acid is also clearly exothermic, but again a significant energy barrier is found (around 24 kcal mol{sup -1} at the CCSD(T) level). The reaction of the most stable protonated isomer of hydroxylamine, NH{sub 3}OH{sup +}, with acetic acid also involves a high barrier (more than 27 kcal mol{sup -1} at the CCSD(T) level). Only the higher energy isomer, NH{sub 2}OH{sup +}{sub 2}, leads to a sensibly lower energy barrier (about 2.3 kcal mol{sup -1} at the CCSD(T) level). Nevertheless, an estimate of the reaction coefficient at low temperatures such as those reigning in the interstellar medium gives very low values. Therefore, it seems that precursors of interstellar glycine could not be efficiently produced from the reactions of hydroxylamine-derived ions with acetic acid.

  7. Characterization of plant materials by pyrolysis-field ionization mass spectrometry: high-resolution mass spectrometry, time-resolved high-resolution mass spectrometry, and Curie-point pyrolysis-gas chromatography/mass spectrometry of spruce needles

    SciTech Connect

    Schulten, H.F.; Simmleit, N.; Mueller, R.

    1989-02-01

    In the course of a forest damage research project spruce needles are analyzed, without pretreatment except drying and milling, by in-source pyrolysis-field ionization mass spectrometry. The mass signals are assigned by using high-resolution mass measurements and thermal degradation products identified by Curie-point pyrolysis-gas chromatography. It is demonstrated that the thermal degradation products characterize the main chemical constituents of spruce needs such as polysaccharides and lignin. Furthermore, thermostable constituents such as lipids, steroids, and flavons are detected. The thermal degradation process is studied by temperature-programmed microfurnace pyrolysis in combination with time-resolved high-resolution mass spectrometry. The integrated interpretation of results achieved by the presented methods can be applied for the universal characterization of complex and in particular nonsoluble, polydisperse biological and geochemical materials.

  8. Quality classification of Spanish olive oils by untargeted gas chromatography coupled to hybrid quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization and metabolomics-based statistical approach.

    PubMed

    Sales, C; Cervera, M I; Gil, R; Portolés, T; Pitarch, E; Beltran, J

    2017-02-01

    The novel atmospheric pressure chemical ionization (APCI) source has been used in combination with gas chromatography (GC) coupled to hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) for determination of volatile components of olive oil, enhancing its potential for classification of olive oil samples according to their quality using a metabolomics-based approach. The full-spectrum acquisition has allowed the detection of volatile organic compounds (VOCs) in olive oil samples, including Extra Virgin, Virgin and Lampante qualities. A dynamic headspace extraction with cartridge solvent elution was applied. The metabolomics strategy consisted of three different steps: a full mass spectral alignment of GC-MS data using MzMine 2.0, a multivariate analysis using Ez-Info and the creation of the statistical model with combinations of responses for molecular fragments. The model was finally validated using blind samples, obtaining an accuracy in oil classification of 70%, taking the official established method, "PANEL TEST", as reference.

  9. Development and validation of an analytical method for determination of 3-chloropropane-1,2-diol in rat blood and urine by gas chromatography-mass spectrometry in negative chemical ionization mode.

    PubMed

    Berger-Preiss, Edith; Gerling, Susanne; Apel, Elisabeth; Lampen, Alfonso; Creutzenberg, Otto

    2010-09-01

    We have developed a highly selective and sensitive method using gas chromatography-mass spectrometry with negative chemical ionization for measuring 3-chloropropane-1,2-diol (3-MCPD) in rat blood and urine. Samples were adsorbed on silica gel, extracted with ethyl acetate, and derivatized by chemical derivatization with heptafluorobutyric acid anhydride. For quantification, matrix-based calibration curves and 3-MCPD-d (5), as an isotope-labeled internal standard, were used. The relative recoveries of 3-MCPD were between 80 and 110% in most cases and the relative standard deviations were typically less than 10%, with some exceptions. The limit of quantification of the method was found to be about 2 ng/mL. In conclusion, a valuable, robust, and sensitive method for detection of 3-MCPD is now available for biokinetics studies. PMID:20640896

  10. Method development for the analysis of N-nitrosodimethylamine and other N-nitrosamines in drinking water at low nanogram/liter concentrations using solid-phase extraction and gas chromatography with chemical ionization tandem mass spectrometry.

    PubMed

    Munch, Jean W; Bassett, Margarita V

    2006-01-01

    N-nitrosodimethylamine (NDMA) is a probable human carcinogen of concern that has been identified as a drinking water contaminant. U.S. Environmental Protection Agency Method 521 has been developed for the analysis of NDMA and 6 additional N-nitrosamines in drinking water at low ng/L concentrations. The method uses solid-phase extraction with coconut charcoal as the sorbent and dichloromethane as the eluent to concentrate 0.50 L water samples to 1 mL. The extracts are analyzed by gas chromatography-chemical ionization tandem mass spectrometry using large-volume injection. Method performance was evaluated in 2 laboratories. Typical analyte recoveries of 87-104% were demonstrated for fortified reagent water samples, and recoveries of 77-106% were demonstrated for fortified drinking water samples. All relative standard deviations on replicate analyses were < 11%. PMID:16640298

  11. Field ionizing elements and applications thereof

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2003-01-01

    A field ionizing element formed of a membrane that houses electrodes therein that are located closer to one another than the mean free path of the gas being ionized. The membrane includes a supporting portion, and a non supporting portion where the ions are formed. The membrane may be used as the front end for a number of different applications including a mass spectrometer, a thruster, an ion mobility element, or an electrochemical device such as a fuel cell.

  12. Non-equilibrium ionized blast wave

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1974-01-01

    The structure of a cylindrical blast wave with ionization at non-LTE conditions was calculated using equations previously developed by Wu and Fu (1970). The degree of ionization was predicted by a modified Saha equation. Temperature profiles show that the temperature at non-LTE conditions is lower than at LTE near the shock front. This corresponds to a higher degree of ionization for the non-LTE limit, which indicates that the neutral gas absorption is much more efficient at non-LTE than at the LTE limit. The decaying velocity under non-LTE is approximately 15% less than under LTE.

  13. Probing Angular Correlations in Sequential Double Ionization

    SciTech Connect

    Fleischer, A.; Woerner, H. J.; Arissian, L.; Liu, L. R.; Meckel, M.; Rippert, A.; Doerner, R.; Villeneuve, D. M.; Corkum, P. B.; Staudte, A.

    2011-09-09

    We study electron correlation in sequential double ionization of noble gas atoms and HCl in intense, femtosecond laser pulses. We measure the photoelectron angular distributions of Ne{sup +} relative to the first electron in a pump-probe experiment with 8 fs, 800 nm, circularly polarized laser pulses at a peak intensity of a few 10{sup 15} W/cm{sup 2}. Using a linear-linear pump-probe setup, we further study He, Ar, and HCl. We find a clear angular correlation between the two ionization steps in the sequential double ionization intensity regime.

  14. Structure elucidation of an artifact discharging from rubber-based vial closures by means of gas chromatography/tandem mass spectrometry.

    PubMed

    Kapp, Thomas; Vetter, Walter

    2006-12-01

    The use of vial closures equipped with butyl rubber septa may lead to sample contamination by rubber additives discharging from the septum material. In this study, the structure elucidation of an artifact causing intense signals in gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and gas chromatographic analyses with electron capture detection is described. Tentative identification of the leached compound was achieved by employing tandem mass spectrometric techniques both in electron capture negative ion and in electron ionization modes. The artifact could thus be characterized as 2-benzothiazolyl-N,N-dimethyl dithiocarbamate, which is a known vulcanization accelerator for rubber. It is conceivable that the identified compound or related substances are also used in other applications. Therefore, two food-related matrixes were investigated for a possible migration of this compound into foods. During these analyses, the tentatively identified rubber additive was detected in an aqueous extract of a rubber seal ring for canning jars. GC/ECNI-MS provided better sensitivity and selectivity than GC/EI-MS for the determination of the rubber additive and other mercaptobenzothiazole-derived substances. PMID:17134153

  15. Neutral depletion versus repletion due to ionization

    SciTech Connect

    Fruchtman, A.; Makrinich, G.; Raimbault, J.-L.; Liard, L.; Rax, J.-M.; Chabert, P.

    2008-05-15

    Recent theoretical analyses which predicted unexpected effects of neutral depletion in both collisional and collisionless plasmas are reviewed. We focus on the depletion of collisionless neutrals induced by strong ionization of a collisionless plasma and contrast this depletion with the effect of strong ionization on thermalized neutrals. The collisionless plasma is analyzed employing a kinetic description. The collisionless neutrals and the plasma are coupled through volume ionization and wall recombination only. The profiles of density and pressure both of the plasma and of the neutral-gas and the profile of the ionization rate are calculated. It is shown that for collisionless neutrals the ionization results in neutral depletion, while when neutrals are thermalized the ionization induces a maximal neutral-density at the discharge center, which we call neutral repletion. The difference between the two cases stems from the relation between the neutral density and pressure. The pressure of the collisionless neutral-gas turns out to be maximal where its density is minimal, in contrast to the case of a thermalized neutral gas.

  16. Identification of alkylated phosphates by gas chromatography-mass spectrometric investigations with different ionization principles of a thermally aged commercial lithium ion battery electrolyte.

    PubMed

    Weber, Waldemar; Kraft, Vadim; Grützke, Martin; Wagner, Ralf; Winter, Martin; Nowak, Sascha

    2015-05-15

    The thermal aging process of a commercial LiPF6 based lithium ion battery electrolyte has been investigated in view of the formation of volatile phosphorus-containing degradation products. Aging products were analyzed by GC-MS. Structure determination of the products was performed by support of chemical ionization MS in positive and negative modes. A fraction of the discovered compounds belongs to the group of fluorophosphates (phosphorofluoridates) which are in suspect of potential toxicity. This is well known for relative derivatives, e.g. diisopropyl fluorophosphate. Another fraction of the identified compounds belongs to the group of trialkyl phosphates. These compounds may provide a positive impact on the thermal and electrochemical performance of Li-based batteries as repeatedly described in the literature.

  17. A bipolar outflow of ionized gas in K3-50A: H76 alpha radio recombination line and continuum observations of K3-50

    NASA Technical Reports Server (NTRS)

    Depree, C. G.; Goss, W. M.; Palmer, Patrick; Rubin, Robert H.

    1994-01-01

    The H II regions near K3-50 (G70.3 + 1.6) have been imaged at high angular resolution (approximately 1 sec .3) in the continuum and the recombination lines H76(sub alpha and He76(sub alpha) using the Very Large Array (VLA). The helium line is detected in only the brightest component K3-50A while the hydrogen line is detected in three components (K3-50A, B and C1). K3-50A shows a pronounced velocity gradient of approximately 150 km/sec/pc along its major axis (P.A. = 160 deg); in addition a wide range of line widths are observed, from 20 to 65 km/sec. Kinematics from the line data and the morphology of the continuum emission suggest that the ionized material associated with K3-50A is undergoing a high-velocity bipolar outflow.

  18. Ionization potentials of seaborgium

    SciTech Connect

    Johnson, E.; Pershina, V.; Fricke, B.

    1999-10-21

    Multiconfiguration relativistic Dirac-Fock values were calculated for the first six ionization potentials of seaborgium and of the other group 6 elements. No experimental ionization potentials are available for seaborgium. Accurate experimental values are not available for all of the other ionization potentials. Ionic radii for the 4+ through 6+ ions of seaborgium are also presented. The ionization potentials and ionic radii obtained will be used to predict some physiochemical properties of seaborgium and its compounds.

  19. Ionization Energies of Lanthanides

    ERIC Educational Resources Information Center

    Lang, Peter F.; Smith, Barry C.

    2010-01-01

    This article describes how data are used to analyze the pattern of ionization energies of the lanthanide elements. Different observed pathways of ionization between different ground states are discussed, and the effects of pairing, exchange, and orbital interactions on ionization energies of the lanthanides are evaluated. When all the above…

  20. Ionization in Atmospheres of Brown Dwarfs and Extrasolar Planets. V. Alfvén Ionization

    NASA Astrophysics Data System (ADS)

    Stark, C. R.; Helling, Ch.; Diver, D. A.; Rimmer, P. B.

    2013-10-01

    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 (>=10-7) 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 10-6-1 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, H2, 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.

  1. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

    SciTech Connect

    Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

    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.

  2. Kinetic simulation of neutral/ionized gas and electrically charged dust in the coma of comet 67P/Churyumov-Gerasimenko

    SciTech Connect

    Tenishev, Valeriy; Rubin, Martin; Combi, Michael R.

    2011-05-20

    The cometary coma is a unique phenomenon in the solar system being a planetary atmosphere influenced by little or no gravity. As a comet approaches the sun, the water vapor with some fraction of other gases sublimate, generating a cloud of gas, ice and other refractory materials (rocky and organic dust) ejected from the surface of the nucleus. Sublimating gas molecules undergo frequent collisions and photochemical processes in the near-nucleus region. Owing to its negligible gravity, comets produce a large and highly variable extensive dusty coma with a size much larger than the characteristic size of the cometary nucleus.The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Both, interpretation of measurements and safety consideration of the spacecraft require modeling of the comet's dusty gas environment.In this work we present results of a numerical study of multispecies gaseous and electrically charged dust environment of comet Chyuryumov-Gerasimenko. Both, gas and dust phases of the coma are simulated kinetically. Photolytic reactions are taken into account. Parameters of the ambient plasma as well as the distribution of electric/magnetic fields are obtained from an MHD simulation of the coma connected to the solar wind. Trajectories of ions and electrically charged dust grains are simulated by accounting for the Lorentz force and the nucleus gravity.

  3. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. II. DUST-INDUCED COLLISIONAL IONIZATION

    SciTech Connect

    Helling, Ch.; Jardine, M.; Mokler, F.

    2011-08-10

    Observations have shown that continuous radio emission and also sporadic H{alpha} and X-ray emission are prominent in singular, low-mass objects later than spectral class M. These activity signatures are interpreted as being caused by coupling of an ionized atmosphere to the stellar magnetic field. What remains a puzzle, however, is the mechanism by which such a cool atmosphere can produce the necessary level of ionization. At these low temperatures, thermal gas processes are insufficient, but the formation of clouds sets in. Cloud particles can act as seeds for electron avalanches in streamers that ionize the ambient gas, and can lead to lightning and indirectly to magnetic field coupling, a combination of processes also expected for protoplanetary disks. However, the precondition is that the cloud particles are charged. We use results from DRIFT-PHOENIX model atmospheres to investigate collisional processes that can lead to the ionization of dust grains inside clouds. We show that ionization by turbulence-induced dust-dust collisions is the most efficient kinetic process. The efficiency is highest in the inner cloud where particles grow quickly and, hence, the dust-to-gas ratio is high. Dust-dust collisions alone are not sufficient to improve the magnetic coupling of the atmosphere inside the cloud layers, but the charges supplied either on grains or within the gas phase as separated electrons can trigger secondary nonlinear processes. Cosmic rays are likely to increase the global level of ionization, but their influence decreases if a strong, large-scale magnetic field is present as on brown dwarfs. We suggest that although thermal gas ionization declines in objects across the fully convective boundary, dust charging by collisional processes can play an important role in the lowest mass objects. The onset of atmospheric dust may therefore correlate with the anomalous X-ray and radio emission in atmospheres that are cool, but charged more than expected by pure

  4. High resolution UV resonance enhanced two-photon ionization spectroscopy with mass selection of biologically relevant molecules in the gas phase

    NASA Astrophysics Data System (ADS)

    Chervenkov, S.; Wang, P. Q.; Karaminkov, R.; Chakraborty, T.; Braun, Juergen E.; Neusser, Hans J.

    2005-04-01

    The high resolution Doppler-free resonance-enhanced two-photon ionization (R2PI) spectroscopy with mass selection of jet-cooled (2-12 K) molecular species is a powerful experimental method providing comprehensive information on both isolated molecules and molecular clusters. We have demonstrated for the first time that this technique can be applied to large molecules and provides detailed information on their conformational structure. It allows rotationally resolved (FWHM = 70 MHz) spectra of the vibronic bands of the S1<--S0 electronic transition of the studied molecular systems to be measured. A specially designed computer-assisted fitting routine based on genetic algorithms is used to determine their rotational constants in the ground and excited electronic states, respectively, and the transition moment ratio. To interpret the experimental information and to discriminate and unambiguously assign the observed approach to the study of the neurotransmitter molecule, ephedrine. The results elucidate the role of the intramolecular hydrogen bonds stabilizing the respective conformations and affecting their intrinsic properties.

  5. Hydrodynamic flow of ions and atoms in partially ionized plasmas

    NASA Astrophysics Data System (ADS)

    Nemirovsky, R. A.; Fredkin, D. R.; Ron, A.

    2002-12-01

    We have derived the hydrodynamic equations of motion for a partially ionized plasma, when the ionized component and the neutral components have different flow velocities and kinetic temperatures. Starting from the kinetic equations for a gas of ions and a gas of atoms we have considered various processes of encounters between the two species: self-collisions, interspecies collisions, ionization, recombination, and charge exchange. Our results were obtained by developing a general approach for the hydrodynamics of a gas in a binary mixture, in particular when the components drift with respect to each other. This was applied to a partially ionized plasma, when the neutral-species gas and the charged-species gas have separate velocities. We have further suggested a generalized version of the relaxation time approximation and obtained the contributions of the interspecies encounters to the transport equations.

  6. Hydrodynamic flow of ions and atoms in partially ionized plasmas.

    PubMed

    Nemirovsky, R A; Fredkin, D R; Ron, A

    2002-12-01

    We have derived the hydrodynamic equations of motion for a partially ionized plasma, when the ionized component and the neutral components have different flow velocities and kinetic temperatures. Starting from the kinetic equations for a gas of ions and a gas of atoms we have considered various processes of encounters between the two species: self-collisions, interspecies collisions, ionization, recombination, and charge exchange. Our results were obtained by developing a general approach for the hydrodynamics of a gas in a binary mixture, in particular when the components drift with respect to each other. This was applied to a partially ionized plasma, when the neutral-species gas and the charged-species gas have separate velocities. We have further suggested a generalized version of the relaxation time approximation and obtained the contributions of the interspecies encounters to the transport equations.

  7. Single photon ionization time-of-flight mass spectrometry with a pulsed electron beam pumped excimer VUV lamp for on-line gas analysis: setup and first results on cigarette smoke and human breath.

    PubMed

    Mühlberger, F; Streibel, T; Wieser, J; Ulrich, A; Zimmermann, R

    2005-11-15

    Single-photon ionization (SPI) using vacuum ultraviolet (VUV) light produced by an electron beam pumped rare gas excimer source has been coupled to a compact and mobile time-of-flight mass spectrometer (TOFMS). The novel device enables real-time on-line monitoring of organic trace substances in complex gaseous matrixes down to the ppb range. The pulsed VUV radiation of the light source is employed for SPI in the ion source of the TOFMS. Ion extraction is also carried out in a pulsed mode with a short time delay with respect to ionization. The experimental setup of the interface VUV light source/time-of-flight mass spectrometer is described, and the novel SPI-TOFMS system is characterized by means of standard calibration gases. Limits of detection down to 50 ppb for aliphatic and aromatic hydrocarbons were achieved. First on-line applications comprised real-time measurements of aromatic and aliphatic trace compounds in mainstream cigarette smoke, which represents a highly dynamic fluctuating gaseous matrix. Time resolution was sufficient to monitor the smoking process on a puff-by-puff resolved basis. Furthermore, human breath analysis has been carried out to detect differences in the breath of a smoker and a nonsmoker, respectively. Several well-known biomarkers for smoke could be identified in the smoker's breath. The possibility for even shorter measurement times while maintaining the achieved sensitivity makes this new device a promising tool for on-line analysis of organic trace compounds in process gases or biological systems.

  8. Identification of chemical warfare agents from vapor samples using a field-portable capillary gas chromatography/membrane-interfaced electron ionization quadrupole mass spectrometry instrument with Tri-Bed concentrator.

    PubMed

    Nagashima, Hisayuki; Kondo, Tomohide; Nagoya, Tomoki; Ikeda, Toru; Kurimata, Naoko; Unoke, Shohei; Seto, Yasuo

    2015-08-01

    A field-portable gas chromatograph-mass spectrometer (Hapsite ER system) was evaluated for the detection of chemical warfare agents (CWAs) in the vapor phase. The system consisted of Tri-Bed concentrator gas sampler (trapping time: 3s(-1)min), a nonpolar low thermal-mass capillary gas chromatography column capable of raising temperatures up to 200°C, a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump for data acquisition, and a personal computer for data analysis. Sample vapors containing as little as 22μg sarin (GB), 100μg soman (GD), 210μg tabun (GA), 55μg cyclohexylsarin (GF), 4.8μg sulfur mustard, 390μg nitrogen mustard 1, 140μg of nitrogen mustard 2, 130μg nitrogen mustard 3, 120μg of 2-chloroacetophenone and 990μg of chloropicrin per cubic meter could be confirmed after Tri-Bed micro-concentration (for 1min) and automated AMDIS search within 12min. Using manual deconvolution by background subtraction of neighboring regions on the extracted ion chromatograms, the above-mentioned CWAs could be confirmed at lower concentration levels. The memory effects were also examined and we found that blister agents showed significantly more carry-over than nerve agents. Gasoline vapor was found to interfere with the detection of GB and GD, raising the concentration limits for confirmation in the presence of gasoline by both AMDIS search and manual deconvolution; however, GA and GF were not subject to interference by gasoline. Lewisite 1, and o-chlorobenzylidene malononitrile could also be confirmed by gas chromatography, but it was hard to quantify them. Vapors of phosgene, chlorine, and cyanogen chloride could be confirmed by direct mass spectrometric detection at concentration levels higher than 2, 140, and 10mg/m(3) respectively, by bypassing the micro-concentration trap and gas chromatographic separation. PMID:26118803

  9. Identification of chemical warfare agents from vapor samples using a field-portable capillary gas chromatography/membrane-interfaced electron ionization quadrupole mass spectrometry instrument with Tri-Bed concentrator.

    PubMed

    Nagashima, Hisayuki; Kondo, Tomohide; Nagoya, Tomoki; Ikeda, Toru; Kurimata, Naoko; Unoke, Shohei; Seto, Yasuo

    2015-08-01

    A field-portable gas chromatograph-mass spectrometer (Hapsite ER system) was evaluated for the detection of chemical warfare agents (CWAs) in the vapor phase. The system consisted of Tri-Bed concentrator gas sampler (trapping time: 3s(-1)min), a nonpolar low thermal-mass capillary gas chromatography column capable of raising temperatures up to 200°C, a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump for data acquisition, and a personal computer for data analysis. Sample vapors containing as little as 22μg sarin (GB), 100μg soman (GD), 210μg tabun (GA), 55μg cyclohexylsarin (GF), 4.8μg sulfur mustard, 390μg nitrogen mustard 1, 140μg of nitrogen mustard 2, 130μg nitrogen mustard 3, 120μg of 2-chloroacetophenone and 990μg of chloropicrin per cubic meter could be confirmed after Tri-Bed micro-concentration (for 1min) and automated AMDIS search within 12min. Using manual deconvolution by background subtraction of neighboring regions on the extracted ion chromatograms, the above-mentioned CWAs could be confirmed at lower concentration levels. The memory effects were also examined and we found that blister agents showed significantly more carry-over than nerve agents. Gasoline vapor was found to interfere with the detection of GB and GD, raising the concentration limits for confirmation in the presence of gasoline by both AMDIS search and manual deconvolution; however, GA and GF were not subject to interference by gasoline. Lewisite 1, and o-chlorobenzylidene malononitrile could also be confirmed by gas chromatography, but it was hard to quantify them. Vapors of phosgene, chlorine, and cyanogen chloride could be confirmed by direct mass spectrometric detection at concentration levels higher than 2, 140, and 10mg/m(3) respectively, by bypassing the micro-concentration trap and gas chromatographic separation.

  10. Central 300 PC of the Galaxy Probed by the Infrared Spectra of H_3^+ and Co: I. Predominance of Warm and Diffuse Gas and High H_2 Ionization Rate

    NASA Astrophysics Data System (ADS)

    Oka, Takeshi; Geballe, Thomas R.; Goto, Miwa; Usuda, Tomonori; Indriolo, Nick

    2016-06-01

    A low-resolution 2.0-2.5 μm survey of ˜500 very red point-like objects in the Central Molecular Zone (CMZ) of our Galaxy, initiated in 2008, has revealed many new bright objects with featureless spectra that are suitable for high resolution absorption spectroscopy of H_3^+ and CO. We now have altogether 48 objects mostly close to the Galactic plane located from 142 pc to the west of Sgr A* to 120 pc east allowing us to probe dense and diffuse gas by H_3^+ and dense gas by CO. Our observations demonstrate that the warm (˜250 K) and diffuse (≤100 cm-3) gas with a large column length (≥30 pc) initially observed toward the brightest star in the CMZ, GCS3-2 of the Quintuplet Cluster, exists throughout the CMZ with the surface filling factor of ˜ 100% dominating the region. The column densities of CO in the CMZ are found to be much less than those in the three foreground spiral arms except in the directions of Sgr B and Sgr E complexes and indicate that the volume filling factor of dense clouds of 10% previously estimated is a gross overestimate for the front half of the CMZ. Nevertheless the predominance of the newly found diffuse molecular gas makes the term "Central Molecular Zone" even more appropriate. The ultra-hot X-rays emitting plasma which some thought to dominate the region must be non existent except near the stars and SNRs. Recently the H_2 fraction f(H_2) in diffuse gas of the CMZ has been reported to be ˜0.6. If we use this value, the cosmic ray H_2 ionization rate ζ of a few times 10-15 s-1 reported earlier^b on the assumption of f(H_2)=1 needs to be increased by a factor of ˜3 since the value is approximately inversely proportional to f(H_2)^2. Geballe, T. R., Oka, T., Lambridges, E., Yeh, S. C. C., Schlegelmilch, B., Goto, M., Westrick, C. W., WI07 at the 70th ISMS, Urbana, IL, USA,2015 Oka, T., Geballe, T. R., Goto, M., Usuda, T., McCall, B. J. 2005, ApJ, 632, 882 Le Petit, F., Ruaud, M., Bron, E., Godard, B., Roueff, E., Languignon, D., Le

  11. A quantitative headspace-solid-phase microextraction-gas chromatography-flame ionization detector method to analyze short chain free fatty acids in rat feces.

    PubMed

    Fiorini, Dennis; Boarelli, Maria Chiara; Gabbianelli, Rosita; Ballini, Roberto; Pacetti, Deborah

    2016-09-01

    This study sought to develop and validate a quantitative method to analyze short chain free fatty acids (SCFAs) in rat feces by solid-phase microextraction and gas chromatography (SPME-GC) using the salt mixture ammonium sulfate and sodium dihydrogen phosphate as salting out agent. Conditioning and extraction time, linearity, limits of detection and quantification, repeatability, and recovery were evaluated. The proposed method allows quantification with improved sensitivity as compared with other methods exploiting SPME-GC. The method has been applied to analyze rat fecal samples, quantifying acetic, propionic, isobutyric, butyric, isopentanoic, pentanoic, and hexanoic acids. PMID:27267560

  12. Method and apparatus utilizing ionizing and microwave radiation for saturation determination of water, oil and a gas in a core sample

    DOEpatents

    Maerefat, Nicida L.; Parmeswar, Ravi; Brinkmeyer, Alan D.; Honarpour, Mehdi

    1994-01-01

    A system for determining the relative permeabilities of gas, water and oil in a core sample has a microwave emitter/detector subsystem and an X-ray emitter/detector subsystem. A core holder positions the core sample between microwave absorbers which prevent diffracted microwaves from reaching a microwave detector where they would reduce the signal-to-noise ratio of the microwave measurements. The microwave emitter/detector subsystem and the X-ray emitter/detector subsystem each have linear calibration characteristics, allowing one subsystem to be calibrated with respect to the other subsystem. The dynamic range of microwave measurements is extended through the use of adjustable attenuators. This also facilitates the use of core samples with wide diameters. The stratification characteristics of the fluids may be observed with a windowed cell separator at the outlet of the core sample. The condensation of heavy hydrocarbon gas and the dynamic characteristics of the fluids are observed with a sight glass at the outlet of the core sample.

  13. Method and apparatus utilizing ionizing and microwave radiation for saturation determination of water, oil and a gas in a core sample

    DOEpatents

    Maerefat, N.L.; Parmeswar, R.; Brinkmeyer, A.D.; Honarpour, M.

    1994-08-23

    A system is described for determining the relative permeabilities of gas, water and oil in a core sample has a microwave emitter/detector subsystem and an X-ray emitter/detector subsystem. A core holder positions the core sample between microwave absorbers which prevent diffracted microwaves from reaching a microwave detector where they would reduce the signal-to-noise ratio of the microwave measurements. The microwave emitter/detector subsystem and the X-ray emitter/detector subsystem each have linear calibration characteristics, allowing one subsystem to be calibrated with respect to the other subsystem. The dynamic range of microwave measurements is extended through the use of adjustable attenuators. This also facilitates the use of core samples with wide diameters. The stratification characteristics of the fluids may be observed with a windowed cell separator at the outlet of the core sample. The condensation of heavy hydrocarbon gas and the dynamic characteristics of the fluids are observed with a sight glass at the outlet of the core sample. 11 figs.

  14. Ionization-chamber smoke detector system

    DOEpatents

    Roe, Robert F.

    1976-10-19

    This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system is designed to reduce false alarms caused by fluctuations in ambient temperature. Means are provided for periodically firing the gas discharge triode and each time recording the triggering voltage required. A computer compares each triggering voltage with its predecessor. The computer is programmed to energize an alarm if the difference between the two compared voltages is a relatively large value indicative of particulates in the measuring chamber and to disregard smaller differences typically resulting from changes in ambient temperature.

  15. Fundamentals of Biomolecule Analysis by Electrospray Ionization Mass Spectrometry

    ERIC Educational Resources Information Center

    Weinecke, Andrea; Ryzhov, Victor

    2005-01-01

    Electrospray ionization (ESI) is a soft ionization technique that allows transfer of fragile biomolecules directly from solution into the gas phase. An instrumental analysis laboratory experiment is designed that would introduce the students to the ESI technique, major parameters of the ion trap mass spectrometers and some caveats in…

  16. Analytical Estimates of the Dispersion Curve in Planar Ionization Fronts

    SciTech Connect

    Arrayas, Manuel; Trueba, Jose L.; Fontelos, Marco A.

    2009-04-27

    Fingers from ionization fronts for a hydrodynamic plasma model result from a balance between impact ionization and electron diffusion in a non-attaching gas. An analytical estimation of the size of the fingers and its dependence on both the electric field and electron diffusion coefficient can be done when the diffusion is low and the electric field is strong.

  17. Gas phase reaction of substituted isoquinolines to carboxylic acids in ion trap and triple quadrupole mass spectrometers after electrospray ionization and collision-induced dissociation.

    PubMed

    Thevis, Mario; Kohler, Maxie; Schlörer, Nils; Schänzer, Wilhelm

    2008-01-01

    Within the mass spectrometric study of bisubstituted isoquinolines that possess great potential as prolylhydroxylase inhibitor drug candidates (e.g., FG-2216), unusually favored gas-phase formations of carboxylic acids after collisional activation were observed. The protonated molecule of [(1-chloro-4-hydroxy-isoquinoline-3-carbonyl)-amino]-acetic acid was dissociated, yielding the 1-chloro-4-hydroxy-isoquinoline-3-carboxylic acid methyleneamide cation. Subsequent dissociation caused the nominal elimination of 11 u that resulted from the loss of HCN and concomitant addition of oxygen to the product ion, which formed the protonated 1-chloro-4-hydroxy-isoquinoline-3-carboxylic acid. The preference of this structure under mass spectrometric conditions was substantiated by tandem mass spectrometry analyses using the corresponding methyl ester (1-chloro-4-hydroxy-isoquinoline-3-carboxylic acid methyl ester) that eliminated methylene (-14 u) upon collisional activation. Moreover, the major product ion of 1-chloro-4-hydroxy-isoquinoline-3-carboxylic acid, which resulted from the loss of water in MS3 experiments, restored the precursor ion structure by re-addition of H2O. Evidences for these phenomena were obtained by chemical synthesis of proposed gas-phase intermediates, H/D exchange experiments, high-resolution/high accuracy mass spectrometry at MSn level, and "ping-pong" analyses (MS7, in which the precursor ion was dissociated and the respective product ion isolated to regenerate the precursor ion for repeated dissociation. Based on these results, dissociation pathways for [(1-chloro-4-hydroxy-isoquinoline-3-carbonyl)-amino]-acetic acid were suggested that can be further utilized for the characterization of structurally related compounds or metabolic products in clinical, forensic, or doping control analysis.

  18. Analytical instruments, ionization sources, and ionization methods

    DOEpatents

    Atkinson, David A.; Mottishaw, Paul

    2006-04-11

    Methods and apparatus for simultaneous vaporization and ionization of a sample in a spectrometer prior to introducing the sample into the drift tube of the analyzer are disclosed. The apparatus includes a vaporization/ionization source having an electrically conductive conduit configured to receive sample particulate which is conveyed to a discharge end of the conduit. Positioned proximate to the discharge end of the conduit is an electrically conductive reference device. The conduit and the reference device act as electrodes and have an electrical potential maintained between them sufficient to cause a corona effect, which will cause at least partial simultaneous ionization and vaporization of the sample particulate. The electrical potential can be maintained to establish a continuous corona, or can be held slightly below the breakdown potential such that arrival of particulate at the point of proximity of the electrodes disrupts the potential, causing arcing and the corona effect. The electrical potential can also be varied to cause periodic arcing between the electrodes such that particulate passing through the arc is simultaneously vaporized and ionized. The invention further includes a spectrometer containing the source. The invention is particularly useful for ion mobility spectrometers and atmospheric pressure ionization mass spectrometers.

  19. Are cosmic rays effective for ionization of the solar nebula?

    NASA Technical Reports Server (NTRS)

    Dolginov, A. Z.; Stepinski, T. F.

    1993-01-01

    In this paper, we argue that the effectiveness of cosmic rays to ionize the bulk of the nebular gas may be further impaired by the influence of the magnetic field on the propagation of cosmic rays. When cosmic rays enter the nebular disk they ionize the gas and make the dynamo generation of magnetic fields possible. However, once magnetic fields are embedded in the nebular gas, the upcoming cosmic rays can no longer penetrate directly into the nebular disk because they start to interact with the magnetic field and lose their energy before propagating significantly toward the midplane. That, in turn, undercuts the ionization source within the bulk of the gas stopping the dynamo action. Nebular dynamo models ignored this back reaction of magnetic fields on cosmic rays. We calculate this back reaction effect, but for the sake of mathematical simplicity, we ignore the effect of magnetic field weakening due to diminishing ionization by cosmic rays.

  20. Development of a multi-residue method for the determination of organic micropollutants in water, sediment and mussels using gas chromatography-tandem mass spectrometry.

    PubMed

    Sánchez-Avila, Juan; Fernandez-Sanjuan, María; Vicente, Joana; Lacorte, Silvia

    2011-09-23

    This study describes the development of a multiresidue method based on gas chromatography-electron ionization-tandem mass spectrometry (GC-EI-MS/MS) for the detection of sixteen polycyclic aromatic hydrocarbons (PAHs), five phthalate esters (PEs), seven polychlorinated biphenyls (PCBs), six polybrominated diphenyl ethers (PBDEs), six alkylphenols (APs), three organochlorined pesticides and their isomers or degradation products (OCPs) and bisphenol A in seawater, river water, wastewater treatment plant (WWTP) effluents, sediments and mussels. Solid phase extraction (SPE) was used for the extraction of target analytes in aqueous samples, and ultrasound assisted extraction for solid samples. GC-EI-MS/MS acquisition conditions in selected reaction monitoring (SRM) using two transitions per compound were optimized. In this way, quantification and unequivocal identification of organic micropollutants were performed in compliance with the Decision 2002/657/EC. Good linearity responses with coefficients of determination higher than 0.99 were obtained. Methodological detection limits (MDLs) in seawater ranged from 0.1 to 6 ng L(-1); in river water from 0.1 to 4.8 ng L(-1); in WWTP effluents from 1 to 75 ng L(-1); in sediments from 1 to 150 ng g(-1) and in mussels from 1 to 125 ng g(-1). MDLs and recovery yields were compared with other published methods and similarities or even improvements were achieved. The optimized method was applied to analyze five samples from each matrix collected in coastal areas, showing its potential use for marine pollution monitoring. PMID:21824622

  1. Beam cooling with ionization losses

    NASA Astrophysics Data System (ADS)

    Rubbia, C.; Ferrari, A.; Kadi, Y.; Vlachoudis, V.

    2006-12-01

    This novel type of Ionization Cooling is an effective method in order to enhance the (strong) interaction probability of slow (few MeV/A) ions stored in a small ring. The many traversals through a thin target strongly improve the nuclear reaction rate with respect to a single-pass collision, in a steady configuration in which ionization losses of a target "foil" (typically few hundred μg/cm 2 thick) are continuously recovered by an RF-cavity. With a flat foil, betatron oscillations are "cooled", but the momentum spread diverges exponentially, since faster (slower) particles ionize less (more) than the average. In order to "cool" the beam also longitudinally, a chromaticity has to be introduced with a wedge-shaped "foil". Therefore, in equilibrium conditions, multiple scattering and straggling are both balanced by phase-space compression. Classic Ionization Cooling [A.A. Kolomensky, Atomnaya Energiya 19 (1965) 534; Yu.M. Ado, V.I. Balbekov, Atomnaya Energiya 31(1) (1971) 40-44; A.N. Skrinsky, V.V. Parkhomchuk, Sov. J. Nucl. Phys. 12 (1981) 3; E.A. Perevendentsev, A.N. Skrinsky, in: Proceedings of the 12th International Conference on High Energy Acceleration, 1983, p. 485] is designed to cool the direct beam until it has been compressed and extracted for further use. In practice, this limits its applicability to non-interacting muon beams. Instead, in this new method, applicable to strongly interacting collisions, the circulating beam is not extracted. Ionization cooling provides "in situ" storage of the beam until it is converted by a nuclear interaction with the target. Simple reactions—for instance 7Li+D→8Li+p—are more favourably produced in the "mirror" kinematical frame, namely with a heavier ion colliding against a gas-jet D 2 target. Kinematics is generally very favourable, with angles in a narrow angular cone (around ˜10° for the mentioned reaction) and with a relatively concentrated outgoing energy spectrum which allows an efficient collection of 8

  2. Determination of 2-, 3-, 4-methylpentanoic and cyclohexanecarboxylic acids in wine: development of a selective method based on solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry and its application to different wines and alcoholic beverages.

    PubMed

    Gracia-Moreno, Elisa; Lopez, Ricardo; Ferreira, Vicente

    2015-02-13

    A method to analyse 2-methylpentanoic, 3-methylpentanoic and 4-methylpentanoic acids as well as cyclohexanecarboxylic acid has been developed and applied to wine and other alcoholic beverages. Selective isolation with solid phase extraction, derivatization with 2,3,4,5,6-pentafluorobenzyl bromide at room temperature for 30 minutes, and further analysis by gas chromatography-mass spectrometry in negative chemical ionization mode provides detection limits between 0.4 and 2.4 ng/L. Good linearity up to 3.6 μg/L, satisfactory reproducibility (RSD<10%) and signal recovery of around 100% represent a robust method of analysis. Concentration data of these analytes in wine and other alcoholic beverages are reported for the first time. The levels found ranged from the method detection limits to 2630 ng/L, 2040 ng/L and 3810 ng/L for 2-, 3- and 4-methylpentanoic acids, respectively, and to 1780 ng/L for cyclohexanecarboxylic acid. There are significant differences depending on the type of wine or beverage. Distilled beverages, beer and aged wines have higher contents in methylpentanoic and cyclohexanecarboxylic acids.

  3. Low-density-solvent-based air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection for the determination of synthetic phenolic antioxidants in milk samples.

    PubMed

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza

    2016-03-01

    A simple and rapid sample pretreatment technique termed low-density-solvent-based air-assisted liquid-liquid microextraction has been developed for the extraction and preconcentration of three synthetic phenolic antioxidants including butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone from milk samples prior to their analysis by gas chromatography with flame ionization detection. In this method, initially trichloroacetic acid as a proteins precipitation agent is added to the sample, and then it is sonicated and centrifuged. The obtained aqueous phase is removed and the analytes extracted by the proposed method using a low-density organic solvent. Some important parameters such as type and volume of extraction solvent, ionic strength, pH, and centrifugation rate and time were studied. Under the optimum conditions, enrichment factors were obtained in the range of 501-614. LODs and quantification were between 0.76-1.16 and 2.66-3.96 ng mL(-1) , respectively. This method is rapid and requires less than 15 min for sample preparation.

  4. Homogeneous liquid-liquid extraction (HoLLE) via flotation combined with gas chromatography-flame ionization detection as a very simple, rapid and sensitive method for the determination of fenitrothion in water samples.

    PubMed

    Mashayekhi, Hossein Ali

    2013-01-01

    Homogeneous liquid-liquid extraction via flotation assistance (HoLLE-FA) and gas chromatography-flame ionization detection (GC-FID) was presented for the extraction and determination of fenitrothion in water samples. In this work, a rapid, simple and efficient HoLLE-FA method was developed based on applying low-density organic solvents without employing centrifugation. A special extraction cell was designed to facilitate the collection of low-density solvent extraction in the determination of fenitrothion in water samples. The water sample solution was added into an extraction cell that contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Under the optimum conditions, the method performance was studied in terms of the linear dynamic range (LDR from 1.0 up to 100 μg L⁻¹), linearity (r² > 0.998), and precision (repeatability < 8.0%). Also, limit of detection (LOD) of 0.4 μg L⁻¹ was obtained for fenitrothion. The applicability of the HoLLE-FA method was evaluated by the extraction and determination of fenitrothion in three different water samples.

  5. Low-density-solvent-based air-assisted liquid-liquid microextraction followed by gas chromatography with flame ionization detection for the determination of synthetic phenolic antioxidants in milk samples.

    PubMed

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza

    2016-03-01

    A simple and rapid sample pretreatment technique termed low-density-solvent-based air-assisted liquid-liquid microextraction has been developed for the extraction and preconcentration of three synthetic phenolic antioxidants including butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone from milk samples prior to their analysis by gas chromatography with flame ionization detection. In this method, initially trichloroacetic acid as a proteins precipitation agent is added to the sample, and then it is sonicated and centrifuged. The obtained aqueous phase is removed and the analytes extracted by the proposed method using a low-density organic solvent. Some important parameters such as type and volume of extraction solvent, ionic strength, pH, and centrifugation rate and time were studied. Under the optimum conditions, enrichment factors were obtained in the range of 501-614. LODs and quantification were between 0.76-1.16 and 2.66-3.96 ng mL(-1) , respectively. This method is rapid and requires less than 15 min for sample preparation. PMID:26763356

  6. Determination of two oxy-pyrimidine metabolites of diazinon in urine by gas chromatography/mass selective detection and liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry.

    PubMed

    Yokley, R A; Shen, N; Cheung, M W

    2000-01-01

    An analytical method was developed for the determination in urine of 2 metabolites of diazinon: 6-methyl-2-(1-methylethyl)-4(1H)-pyrimidinone (G-27550) and 2-(1-hydroxy-1-methylethyl)-6-methyl-4(1H)-pyrimidinone (GS-31144). Two of the urine sample preparation procedures presented rely on gas chromatography/mass selective detection (GC/MSD) in the selected ion monitoring mode for determination of G-27550. For fast sample preparation and a limit of quantitation (LOQ) of 1.0 ppb, urine samples were purified by using ENV+ solid-phase extraction (SPE) columns. For analyte confirmation at an LOQ of 0.50 ppb, classical liquid/liquid partitioning was used before further purification in a silica SPE column. An SPE sample preparation procedure and liquid chromatography/electrospray ionization/mass spectrometry/mass spectrometry (LC/ESI/MS/MS) were used for both G-27550 and GS-31144. The limit of detection was 0.01 ng for G-27550 with GC/MSD, and 0.016 ng when LC/ESI/MS/MS was used for both G-27550 and GS-31144. The LOQ was 0.50 ppb for G-27550 when GC/MSD and the partitioning/SPE sample preparation procedure were used, and 1.0 ppb for the SPE only sample preparation procedure. The LOQ was 1.0 ppb for both analytes when LC/ESI/MS/MS was used. PMID:11048865

  7. Homogeneous liquid-liquid extraction (HoLLE) via flotation combined with gas chromatography-flame ionization detection as a very simple, rapid and sensitive method for the determination of fenitrothion in water samples.

    PubMed

    Mashayekhi, Hossein Ali

    2013-01-01

    Homogeneous liquid-liquid extraction via flotation assistance (HoLLE-FA) and gas chromatography-flame ionization detection (GC-FID) was presented for the extraction and determination of fenitrothion in water samples. In this work, a rapid, simple and efficient HoLLE-FA method was developed based on applying low-density organic solvents without employing centrifugation. A special extraction cell was designed to facilitate the collection of low-density solvent extraction in the determination of fenitrothion in water samples. The water sample solution was added into an extraction cell that contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Under the optimum conditions, the method performance was studied in terms of the linear dynamic range (LDR from 1.0 up to 100 μg L⁻¹), linearity (r² > 0.998), and precision (repeatability < 8.0%). Also, limit of detection (LOD) of 0.4 μg L⁻¹ was obtained for fenitrothion. The applicability of the HoLLE-FA method was evaluated by the extraction and determination of fenitrothion in three different water samples. PMID:23934566

  8. Quality classification of Spanish olive oils by untargeted gas chromatography coupled to hybrid quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization and metabolomics-based statistical approach.

    PubMed

    Sales, C; Cervera, M I; Gil, R; Portolés, T; Pitarch, E; Beltran, J

    2017-02-01

    The novel atmospheric pressure chemical ionization (APCI) source has been used in combination with gas chromatography (GC) coupled to hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) for determination of volatile components of olive oil, enhancing its potential for classification of olive oil samples according to their quality using a metabolomics-based approach. The full-spectrum acquisition has allowed the detection of volatile organic compounds (VOCs) in olive oil samples, including Extra Virgin, Virgin and Lampante qualities. A dynamic headspace extraction with cartridge solvent elution was applied. The metabolomics strategy consisted of three different steps: a full mass spectral alignment of GC-MS data using MzMine 2.0, a multivariate analysis using Ez-Info and the creation of the statistical model with combinations of responses for molecular fragments. The model was finally validated using blind samples, obtaining an accuracy in oil classification of 70%, taking the official established method, "PANEL TEST", as reference. PMID:27596432

  9. Electron ionization of acetylene

    NASA Astrophysics Data System (ADS)

    King, Simon J.; Price, Stephen D.

    2007-11-01

    Relative partial ionization cross sections and precursor specific relative partial ionization cross sections for fragment ions formed by electron ionization of C2H2 have been measured using time-of-flight mass spectrometry coupled with a 2D ion-ion coincidence technique. We report data for the formation of H+, H2+, C2+, C+/C22+, CH +/C2H22+, CH2+, C2+, and C2H + relative to the formation of C2H2+, as a function of ionizing electron energy from 30-200eV. While excellent agreement is found between our data and one set of previously published absolute partial ionization cross sections, some discrepancies exist between the results presented here and two other recent determinations of these absolute partial ionization cross sections. We attribute these differences to the loss of some translationally energetic fragment ions in these earlier studies. Our relative precursor-specific partial ionization cross sections enable us, for the first time, to quantify the contribution to the yield of each fragment ion from single, double, and triple ionization. Analysis shows that at 50eV double ionization contributes 2% to the total ion yield, increasing to over 10% at an ionizing energy of 100eV. From our ion-ion coincidence data, we have derived branching ratios for charge separating dissociations of the acetylene dication. Comparison of our data to recent ab initio/RRKM calculations suggest that close to the double ionization potential C2H22+ dissociates predominantly on the ground triplet potential energy surface (Σg-3) with a much smaller contribution from dissociation via the lowest singlet potential energy surface (Δg1). Measurements of the kinetic energy released in the fragmentation reactions of C2H22+ have been used to obtain precursor state energies for the formation of product ion pairs, and are shown to be in good agreement with available experimental data and with theory.

  10. Disposable ionic liquid coating for headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes in paints followed by gas chromatography-flame ionization detection.

    PubMed

    Liu, Jing-Fu; Li, Ning; Jiang, Gui-bin; Liu, Jie-min; Jönsson, Jan Ake; Wen, Mei-juan

    2005-02-25

    Solid-phase microextraction (SPME) with a disposable ionic liquid (IL) coating was developed for headspace extraction of benzene, toluene, ethylbenzene, and xylenes (BTEX) in paints. The SPME fiber was coated with IL prior to every extraction, then the analytes were extracted and desorbed on the injection port of gas chromatography, and finally the IL coating on the fiber was washed out with solvents. The coating and washing out of IL from the fiber can be finished in a few minutes. This disposable IL-coated fiber was applied to determine BTEX in water-soluble paints with results in good agreement with that obtained by using commercially available SPME fibers. For all the four studied paints samples, the benzene contents were under the detection limits, but relatively high contents of toluene, ethylbenzene and xylenes (56-271 microg g(-1)) were detected with spiked recoveries in the range of 70-114%. Compared to the widely used commercially available SPME fibers, this proposed disposable IL-coated fiber has much lower cost per determination, comparable reproducibility (RSD < 11%), and no carryover between each determination. Considering that IL possess good extractability for various organic compounds and metals ions, and that task-specific IL can be designed and synthesized for selective extraction of target analytes, this disposable IL coating SPME might has great potential in sample preparation.

  11. Determination of plant stanols and plant sterols in phytosterol enriched foods with a gas chromatographic-flame ionization detection method: NMKL collaborative study.

    PubMed

    Laakso, Päivi H

    2014-01-01

    This collaborative study with nine participating laboratories was conducted to determine the total plant sterol and/or plant stanol contents in phytosterol fortified foods with a gas chromatographic method. Four practice and 12 test samples representing mainly commercially available foodstuffs were analyzed as known replicates. Twelve samples were enriched with phytosterols, whereas four samples contained only natural contents of phytosterols. The analytical procedure consisted of two alternative approaches: hot saponification method, and acid hydrolysis treatment prior to hot saponification. As a result, sterol/stanol compositions and contents in the samples were measured. The amounts of total plant sterols and total plant stanols varying from 0.005 to 8.04 g/100 g product were statistically evaluated after outliers were eliminated. The repeatability RSD (RSDr) varied from 1.34 to 17.13%. The reproducibility RSD (RSDR) ranged from 3.03 to 17.70%, with HorRat values ranging from 0.8 to 2.1. When only phytosterol enriched food test samples are considered, the RSDr ranged from 1.48 to 6.13%, the RSD, ranged from 3.03 to 7.74%, and HorRat values ranged from 0.8 to 2.1. Based on the results of this collaborative study, the study coordinator concludes the method is fit for its purpose.

  12. Determination of glutamic acid and gamma-aminobutyric acid in Ringer's solution without desalination at the femtomole level by gas chromatography chemical ionization mass spectrometry.

    PubMed

    Murayama, K; Shindo, N; Mineki, R; Ohta, K

    1981-04-01

    For the quantification of glutamic acid in Ringer's solution, pentafluoropropionic methyl ester was the most sensitive derivative. The detectable concentration was 0.01 microM glutamic acid in Ringer's solution; the amount of the preparation was 1 pmol and the injection into a gas chromatograph mass spectrometer was 10 fmol. For the quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was detectable at a concentration of 0.01 microM. Ringer's salts facilitated acylation in the order heptafluorobutyric anhydride greater than pentafluoropropionic anhydride greater than trifluoroacetic anhydride. The effect depended on esterification of carboxy groups in the order methyl ester greater than hexafluoropropionyl ester greater than butyl ester. Sodium carbonate, sodium acetate and sodium citrate also facilitated acylation with pentafluoroproionic anhydride, while sodium phosphate inhibited the acylation and sodium sulfate inhibited it slightly. The pentafluoropropionic methyl ester of glutamic acid was stable for up to 10 days, when it was dissolved in acetone and stored at -18 degrees C.

  13. Fully automated determination of the sterol composition and total content in edible oils and fats by online liquid chromatography-gas chromatography-flame ionization detection.

    PubMed

    Nestola, Marco; Schmidt, Torsten C

    2016-09-01

    Sterol analysis of edible oils and fats is important in authenticity control. The gas chromatographic determination of the sterol distribution and total content is described by ISO norm 12228. Extraction, purification, and detection of the sterols are time-consuming and error-prone. Collaborative trials prove this regularly. Purification by thin-layer chromatography (TLC) and robust GC determination of all mentioned sterols is not straightforward. Therefore, a fully automated LC-GC-FID method was developed to facilitate the determination of sterols. The only manual step left was to weigh the sample into an autosampler vial. Saponification and extraction were performed by an autosampler while purification, separation, and detection were accomplished by online coupled normal-phase LC-GC-FID. Interlacing of sample preparation and analysis allowed an average sample throughput of one sample per hour. The obtained quantitative results were fully comparable with the ISO method with one apparent exception. In the case of sunflower oils, an additional unknown sterol was detected generally missed by ISO 12228. The reason was found in the omission of sterol silylation before subjection to GC-FID. The derivatization reaction changed the retention time and hid this compound behind a major sterol. The compound could be identified as 14-methyl fecosterol. Its structure was elucidated by GC-MS and ensured by HPLC and GC retention times. Finally, validation of the designed method confirmed its suitability for routine environments. PMID:27522150

  14. Soft ionization device with characterization systems and methods of manufacture

    NASA Technical Reports Server (NTRS)

    Hartley, Frank T. (Inventor)

    2004-01-01

    Various configurations of characterization systems such as ion mobility spectrometers and mass spectrometers are disclosed that are coupled to an ionization device. The ionization device is formed of a membrane that houses electrodes therein that are located closer to one another than the mean free path of the gas being ionized. Small voltages across the electrodes generate large electric fields which act to ionize substantially all molecules passing therethrough without fracture. Methods to manufacture the mass spectrometer and ion mobility spectrometer systems are also described.

  15. The primordial abundance of deuterium: ionization correction

    NASA Astrophysics Data System (ADS)

    Cooke, Ryan; Pettini, Max

    2016-01-01

    We determine the relative ionization of deuterium and hydrogen in low metallicity damped Lyman α (DLA) and sub-DLA systems using a detailed suite of photoionization simulations. We model metal-poor DLAs as clouds of gas in pressure equilibrium with a host dark matter halo, exposed to the Haardt & Madau background radiation of galaxies and quasars at redshift z ≃ 3. Our results indicate that the deuterium ionization correction correlates with the H I column density and the ratio of successive ion stages of the most commonly observed metals. The N(N II)/N(N I) column density ratio provides the most reliable correction factor, being essentially independent of the gas geometry, H I column density, and the radiation field. We provide a series of convenient fitting formulae to calculate the deuterium ionization correction based on observable quantities. The ionization correction typically does not exceed 0.1 per cent for metal-poor DLAs, which is comfortably below the current measurement precision (2 per cent). However, the deuterium ionization correction may need to be applied when a larger sample of D/H measurements becomes available.

  16. Fast procedure for the analysis of poly(hydroxyalkanoates) in bacterial cells by off-line pyrolysis/gas-chromatography with flame ionization detector.

    PubMed

    Torri, Cristian; Cordiani, Helena; Samorì, Chiara; Favaro, Lorenzo; Fabbri, Daniele

    2014-09-12

    Poly(hydroxyalkanoates) (PHAs) are polyesters formed by saturated short chain hydroxyacids, among which 3-hydroxybutanoic (HB) and 3-hydroxypentanoic (3-hydroxyvalerate, HV) are the most common monomers of homopolymers (e.g. poly(3-hydroxybutyrate), PHB) and copolymers (e.g. poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), PHB-HC). The most widely used approach for their determination is the polymer methanolysis followed by gas chromatography-mass spectrometry (GC-MS) analysis of the methylated monomers; this procedure generally requires the use of additional reagents (e.g. sulfuric acid) and is performed with harmful chlorinated solvents, such as chloroform. The development of fast routine solventless methods for the quantitative determination of PHAs and their monomeric composition is highly desirable to reduce sample pretreatment, speed up the analysis and decrease overall costs. It has been reported that under thermal treatment (e.g. pyrolysis, Py), PHAs are degraded in high yield (>40%, w/wPHA) into the corresponding 2-alkenoic acid (e.g. crotonic acid from PHB). This work aimed at investigating this reaction for direct analysis of PHAs in bacterial cells. The sample was directly subjected to pyrolysis and trapped pyrolysis products were analyzed by GC-FID. Off-line Py/GC-FID was first optimized on pure polymers with different monomer composition (PHB, PHB-HV, PHB-HC) and then applied to bacterial samples deriving from both mixed microbial cultures or selected strains, containing various types and amounts of PHAs. The Py/GC-FID method provided RSD <15% range, limit of detection of 100μg (1% PHAs in biomass), and results comparable to that of methanolysis (R(2)=0.9855), but with minimal sample pretreatment. PMID:25069742

  17. Modeling of Ionization Physics with the PIC Code OSIRIS

    SciTech Connect

    Deng, S.; Tsung, F.; Lee, S.; Lu, W.; Mori, W.B.; Katsouleas, T.; Muggli, P.; Blue, B.E.; Clayton, C.E.; O'Connell, C.; Dodd, E.; Decker, F.J.; Huang, C.; Hogan, M.J.; Hemker, R.; Iverson, R.H.; Joshi, C.; Ren, C.; Raimondi, P.; Wang, S.; Walz, D.; /Southern California U. /UCLA /SLAC

    2005-09-27

    When considering intense particle or laser beams propagating in dense plasma or gas, ionization plays an important role. Impact ionization and tunnel ionization may create new plasma electrons, altering the physics of wakefield accelerators, causing blue shifts in laser spectra, creating and modifying instabilities, etc. Here we describe the addition of an impact ionization package into the 3-D, object-oriented, fully parallel PIC code OSIRIS. We apply the simulation tool to simulate the parameters of the upcoming E164 Plasma Wakefield Accelerator experiment at the Stanford Linear Accelerator Center (SLAC). We find that impact ionization is dominated by the plasma electrons moving in the wake rather than the 30 GeV drive beam electrons. Impact ionization leads to a significant number of trapped electrons accelerated from rest in the wake.

  18. The Extended Ionized Halos and Bridge of the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Krishnarao, Dhanesh; Smart, Brianna; Haffner, L. Matthew; Barger, Kathleen; Madsen, Gregory J.; Hill, Alex S.; Gaensler, Bryan M.

    2016-01-01

    The Wisconsin H-Alpha Mapper (WHAM) has revealed ubiquitous ionized emission throughout the gas complexes formed by the dynamic history of the Magellanic Clouds. We present an overview of the immediate environment around the galaxies themselves, including ionized halos of the Small and Large Magellanic Clouds (SMC & LMC) as well as the bridge of material between them. Using WHAM, Barger et al. (2013) found Hα emission extending throughout and beyond H I in the Bridge. We add these new maps of the SMC and LMC to provide the first complete view of the diffuse ionized gas near the interacting system. At R ~ 30,000, WHAM can cleanly separate diffuse emission at Magellanic velocities from the Milky Way and terrestrial sources to the limit of atmospheric line confusion (~ 10s of mR). We find that ionized gas extends at least 5° beyond the traditional boundary of the SMC when compared to recent deep-imaging surveys (e.g., MCELS; Smith et al. 2005). The diffuse ionized emission extent is similar to the neutral gas extent as traced by 21 cm emission. We compare the kinematic signatures between the neutral and ionized components throughout the region. Comprehensive multi-wavelength surveys are also underway to examine how physical parameters and ionization processes vary in these extended systems. WHAM research and operations are supported through NSF Award AST-1108911.

  19. A prototype ionization profile monitor for RHIC

    SciTech Connect

    Connolly, R.; Cameron, P.; Ryan, W.

    1997-07-01

    Transverse beam profiles in the Relativistic Heavy-Ion Collider (RHIC) will be measured with ionization profile monitors (IPM`s). Each IPM collects and measures the distribution of electrons in the beamline resulting from residual gas ionization during bunch passage. The electrons are swept transversely from the beamline and collected on strip anodes oriented parallel to the beam axis. At each bunch passage the charge pulses are amplified, integrated, and digitized for display as a profile histogram. A prototype detector was tested in the injection line during the RHIC Sextant Test. This paper describes the detector and gives results from the beam tests.

  20. Biological Effects of Ionizing Radiation

    DOE R&D Accomplishments Database

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.