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Sample records for chemical ionisation mass

  1. Derivatisation and gas chromatography-chemical ionisation mass spectrometry of selected synthetic and natural endocrine disruptive chemicals.

    PubMed

    Lerch, Oliver; Zinn, Peter

    2003-03-28

    Methods for ultra trace detection of endocrine disruptive chemicals (EDCs) are needed because of their low levels of impact. Twenty-one EDCs were selected, including 17beta-estradiol, 17alpha-ethinylestradiol, 17beta-testosterone and bisphenol A. Derivatisation with eight different fluorine containing compounds was examined. All EDCs could be derivatised automatedly (autosampler) with heptafluorobutyric acid (HFB) anhydride and trifluoroacetic acid (TFA) anhydride, respectively. The detection of these HFB and TFA derivatives in different chemical ionisation modes was studied. Fourteen different reagent gases, including methane, ammonia, acetone and water, were tested with the HFB and TFA derivatives in the negative chemical ionisation mode. Furthermore both types of derivatives were measured in positive chemical ionisation mode. Methane or water provide a good detection of all 21 TFA derivatives and create mass spectra with few fragmentation and characteristic mass peaks. This could serve as a basis for tandem or multiple mass spectrometric measurements.

  2. Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

    NASA Astrophysics Data System (ADS)

    Bannan, T.; Booth, M.; Benyezzar, M.; Bacak, A.; Alfarra, M. R. R.; Topping, D. O.; Percival, C.

    2015-12-01

    Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

  3. Application of Lithium Attachment Mass Spectrometry for Knudsen Evaporation and Chemical Ionisation Mass Spectrometry (KEMS, CIMS)

    NASA Astrophysics Data System (ADS)

    Bannan, Thomas; Booth, A. Murray; Alfarra, Rami; Bacak, Asan; Pericval, Carl

    2016-04-01

    Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting and sensitive method for detection of volatile species in the gas phase. The design, manufacture, and results from lithium ion attachment ionisation sources for two mass spectrometry systems are presented. Trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure (VP) measurements using a modified Knudsen Effusion Mass Spectrometer (KEMS) are presented. The Li+ modified CIMS provided limits of detection of 4 ppt for acetone, 0.2 ppt for formic acid, 15 ppt for nitric acid and 120 ppt from ammonia. Despite improvements, the problem of burnout remained persistent. The Li+ CIMS would unlikely be suitable for field or aircraft work, but could be appropriate for certain lab applications. The KEMS currently utilizes an electron impact (EI) ionisation source which provides a highly sensitive source, with the drawback of fragmentation of ionized molecules (Booth et al., 2009). Using Li+ KEMS the VP of samples can be measured without fragmentation and can therefore be used to identify VPs of individual components in mixtures. The validity of using Li+ for determining the VP of mixtures was tested by making single component VP measurements, which showed good agreement with EI measurements of Poly ethylene glycol (PEG) 3 and PEG 4, both when individually measured and when mixed. The Li+ KEMS was then used to investigate a system of atmospheric relevance, α-pinene secondary organic aerosol, generated in a reaction chamber (Alfarra et al., 2012). The VPs of the individual components from this generated sample are within the range we expect for compounds capable of partitioning between the particle and gas phase of an aerosol (0.1-10-5 Pa). Li+ source has a calculated sensitivity approximately 75 times less than that of EI, but the lack of fragmentation using the Li+ source is a significant advantage.

  4. Structural elucidation of organic contaminants by chemical ionisation mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moldovan, Zaharie

    2009-08-01

    The PI-CI mass spectra formation for a new family of aromatic amines, with general formula: R1-Ph-NH-Ph-R2 is discussed in correlation with the R1 and R2 structure. The compounds where isolated from some environmental samples by GC/MS technique. The characteristic ions are produced by rearrangement processes involving olefin and alkane neutral molecule elimination from [M+H]+ and sole olefin molecule elimination from [M+ C2H5]+.

  5. Laser Ablation/Ionisation Mass Spectrometry: Sensitive and Quantitative Chemical Depth Profiling of Solid Materials.

    PubMed

    Riedo, Andreas; Grimaudo, Valentine; Moreno-García, Pavel; Neuland, Maike B; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2016-01-01

    Direct quantitative and sensitive chemical analysis of solid materials with high spatial resolution, both in lateral and vertical direction is of high importance in various fields of analytical research, ranging from in situ space research to the semiconductor industry. Accurate knowledge of the chemical composition of solid materials allows a better understanding of physical and chemical processes that formed/altered the material and allows e.g. to further improve these processes. So far, state-of-the-art techniques such as SIMS, LA-ICP-MS or GD-MS have been applied for chemical analyses in these fields of research. In this report we review the current measurement capability and the applicability of our Laser Ablation/Ionisation Mass Spectrometer (instrument name LMS) for the chemical analysis of solids with high spatial resolution. The most recent chemical analyses conducted on various solid materials, including e.g. alloys, fossils and meteorites are discussed.

  6. Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry of bacteriochlorophylls from Chlorobiaceae: characteristic fragmentations.

    PubMed

    Airs, Ruth L; Keely, Brendan J

    2002-01-01

    Atmospheric pressure chemical ionisation liquid chromatography/mass spectrometry/mass spectrometry (APCI-LC/MS/MS) has been applied to the study of bacteriochlorophylls c, d, and e of phototrophic prokaryotes. Cultures of Chlorobiaceae containing bacteriochlorophyll c, d or e were examined using a high-resolution high-performance liquid chromatography (HPLC) method and APCI-LC/MS/MS employing post-column addition of formic acid. The results reveal complex distributions of bacteriochlorophyll homologues, with some closely eluting species giving isobaric protonated molecules. On-line LC/MS/MS studies reveal characteristic fragment ions for bacteriochlorophylls c, d, and e. Fragmentations involving loss of the extended alkyl substituents that are unique to bacteriochlorophylls c, d and e and their derivatives have been rationalised by studying the phaeophorbides and the results applied to the direct study of the bacteriochlorophylls.

  7. Chemical profile of mango (Mangifera indica L.) using electrospray ionisation mass spectrometry (ESI-MS).

    PubMed

    Oliveira, Bruno G; Costa, Helber B; Ventura, José A; Kondratyuk, Tamara P; Barroso, Maria E S; Correia, Radigya M; Pimentel, Elisângela F; Pinto, Fernanda E; Endringer, Denise C; Romão, Wanderson

    2016-08-01

    Mangifera indica L., mango fruit, is consumed as a dietary supplement with purported health benefits; it is widely used in the food industry. Herein, the chemical profile of the Ubá mango at four distinct maturation stages was evaluated during the process of growth and maturity using negative-ion mode electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI(-)FT-ICR MS) and physicochemical characterisation analysis (total titratable acidity (TA), total soluble solids (TSS), TSS/TA ratio, and total polyphenolic content). Primary (organic acids and sugars) and secondary metabolites (polyphenolic compounds) were mostly identified in the third maturation stage, thus indicating the best stage for harvesting and consuming the fruit. In addition, the potential cancer chemoprevention of the secondary metabolites (phenolic extracts obtained from mango samples) was evaluated using the induction of quinone reductase activity, concluding that fruit polyphenols have the potential for cancer chemoprevention.

  8. CF3(+) and CF2H(+): new reagents for n-alkane determination in chemical ionisation reaction mass spectrometry.

    PubMed

    Blake, Robert S; Ouheda, Saleh A; Evans, Corey J; Monks, Paul S

    2016-11-28

    Alkanes provide a particular analytical challenge to commonly used chemical ionisation methods such as proton-transfer from water owing to their basicity. It is demonstrated that the fluorocarbon ions CF3(+) and CF2H(+), generated from CF4, as reagents provide an effective means of detecting light n-alkanes in the range C2-C6 using direct chemical ionisation mass spectrometry. The present work assesses the applicability of the reagents in Chemical Ionisation Mass Spectrometric (CI-TOF-MS) environments with factors such as high moisture content, operating pressures of 1-10 Torr, accelerating electric fields (E/N) and long-lived intermediate complex formation. Of the commonly used chemical ionisation reagents, H3O(+) and NO(+) only react with hexane and higher while O2(+) reacts with all the target samples, but creates significant fragmentation. By contrast, CF3(+) and CF2H(+) acting together were found to produce little or no fragmentation. In dry conditions with E/N = 100 Td or higher the relative intensity of CF2H(+) to CF3(+) was mostly less than 1% but always less than 3%, making CF3(+) the main reagent ion. Using O2(+) in a parallel series of experiments, a substantially greater degree of fragmentation was observed. The detection sensitivities of the alkanes with CF3(+) and CF2H(+), while relatively low, were found to be better than those observed with O2(+). Experiments using alkane mixtures in the ppm range have shown the ionisation technique based on CF3(+) and CF2H(+) to be particularly useful for measurements of alkane/air mixtures found in polluted environments. As a demonstration of the technique's effectiveness in complex mixtures, the detection of n-alkanes in a smoker's breath is demonstrated.

  9. Rapid screening method for determination of Ecstasy and amphetamines in urine samples using gas chromatography-chemical ionisation mass spectrometry.

    PubMed

    Pellegrini, M; Rosati, F; Pacifici, R; Zuccaro, R; Romolo, F S; Lopez, A

    2002-04-05

    The need for analytical screening tests more reliable and valid to detect amphetamine and related "designer drugs" in biological samples is becoming critical, due to the increasing diffusion of these drugs on the European illegal market. The most common screening procedures based on immunoassays suffer a number of limitations, including low sensitivity, lack of specificity and limited number of detectable substances. This paper describes a screening method based on gas-chromatography-mass-spectrometry (GC/MS) using positive chemical ionisation (PCI) detection. Methanol was used as reactant gas in the ionisation chamber. Molecular ions of different compounds were monitored, allowing a sensitivity of 5-10 ng/ml with high selectivity. The sensitivity of the method gives positive results in samples taken 48-72 h after intake of one dose of 50-100 mg. The method is simple and rapid. Sample preparation was limited to one liquid-liquid extraction, without any hydrolysis and derivatisation. Hydrolysis is critical to identify metabolites excreted as conjugates. Blank urine samples spiked with known amounts of amphetamine (AM), methylamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethylamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA) and methylenedioxyphenyl-N-methyl-2-butanamine (MBDB) were analysed. The method was successfully tested on real samples of urine from people, whose use of amphetamine was suspected, and results were compared with results obtained with immunoassays.

  10. High-performance liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry determination of zaleplon in human plasma.

    PubMed

    Zhang, Beibei; Zhang, Zunjian; Tian, Yuan; Xu, Fengguo; Chen, Yun

    2006-02-24

    A sensitive and specific liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry (LC-APCI-MS) method has been developed and validated for the identification and quantification of zaleplon in human plasma using estazolam as an internal standard (IS). After the addition of estazolam and 2.0 M sodium hydroxide solution, plasma samples were extracted with ethyl acetate and then the organic layer was evaporated to dryness. The reconstituted solution of the residue was injected onto a prepacked Shim-pack VP-ODS C18 (250 mm x 2.0 mm i.d.) column and chromatographed with a mobile phase comprised of methanol:water (70:30) at a flow-rate of 0.2 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via atmospheric pressure chemical ionization (APCI) source. The mean standard curve was linear (r = 0.9991) over the concentration range of 0.2-100 ng/ml and had good back-calculated accuracy and precision. The intra-day and inter-day precisions were within 10% relative standard deviation and accuracy ranged from 85% to 115%. The limit of detection was 0.1 ng/ml. The validated LC-APCI-MS method has been used successfully to study zaleplon pharmacokinetic, bioavailability and bioequivalence in 18 adult volunteers.

  11. Analysis of oilfield produced waters and production chemicals by electrospray ionisation multi-stage mass spectrometry (ESI-MSn).

    PubMed

    McCormack, P; Jones, P; Hetheridge, M J; Rowland, S J

    2001-10-01

    Large quantities of diverse polar organic chemicals are routinely discharged from oil production platforms in so-called produced waters. The environmental fate of many of these is unknown since few methods exist for their characterisation. Preliminary investigations into the use of multistage electrospray ionisation ion trap mass spectrometry (ESI-MSn) show its potential for the identification and quantification of compounds in specialty oilfield chemicals (corrosion inhibitors, scale inhibitors, biocides and demulsifiers) and produced waters. Multiple stage mass spectrometry (MSn) with both positive and negative ion detection allows high specificity detection and characterisation of a wide range of polar and charged molecules. For example, linear alkylbenzenesulfonates (LAS), alkyldimethylbenzylammonium compounds, 2-alkyl-1-ethylamine-2-imidazolines, 2-alkyl-1-[N-ethylalkylamide]-2-imidazolines and a di-[alkyldimethylammonium-ethyl]ether were all identified and characterised in commercial formulations and/or North Sea oilfield produced waters. The technique should allow the marine environmental effects and fates of some of these polar compounds to be studied.

  12. Aqueous phototransformation of zinc pyrithione Degradation kinetics and byproduct identification by liquid chromatography--atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Sakkas, V A; Shibata, K; Yamaguchi, Y; Sugasawa, S; Albanis, T

    2007-03-16

    The photochemical behavior of the antifouling agent zinc pyrithione (ZnPT) was studied in aqueous media of different composition under simulated solar irradiation using a xenon light source. The influence of important constituents of natural water (dissolved organic matter and nitrate) was also examined using a multivariate kinetic model. It was found that photodegradation proceeds via a pseudo first-order reaction. Kinetic experiments were monitored by LC-MS and photolytic half-lives ranging between 9.2 and 15.1 min have been observed. The increasing concentration of dissolved organic matter (DOM) accelerates the photolysis reaction, while the effect of nitrate ions was also positive since it increased the degradation rate, but to a lesser extent. Irradiation of the aqueous ZnPT solutions gave rise to several transformation products that were isolated by means of solid-phase extraction using poly(styrene-divinylbenzene) extraction disks. These byproducts were identified using liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry. Besides 2-pyridinesulfonic-acid, other degradation products formed included pyridine-N-oxide, 2-mercaptopyridine, 2,2'-dithiobis(pyridine-N-oxide), 2,2-dipyridyl disulfide and the pyridine/pyrithione mixed disulfide, 2,2'-dithiobispyridine mono-N-oxide (PPMD).

  13. Online antioxidant activity and ultra-performance LC-electrospray ionisation-quadrupole time-of-fight mass spectrometry for chemical fingerprinting of Indian polyherbal formulations.

    PubMed

    Bhandari, Pamita; Kumar, Neeraj; Khan, Shahid M; Bhutani, Kamlesh K

    2016-01-01

    A HPLC-DAD-DPPH method was developed for evaluating the 1, 1-diphenyl-2-picryl hydrazyl free radical scavenging activity of ethylacetate extracts of different polyherbal formulations (draksarista, draksava, lohasava and arvindasava) by using RP-18e column. The ethylacetate extract from polyherbal, 'draksarista' exhibited maximum free radical scavenging activity (99.9 ± 0.38%) followed by draksava (99.8 ± 0.34%), lohasava (98.5 ± 0.30%) and arvindasava (42.3 ± 0.34%) at 100 μg mL(-1). Simultaneously, ultra-performance liquid chromatography coupled with electrospray ionisation-quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) was used to study chemical composition of the ethylacetate extracts of formulations. The characteristic electrospray mass ionisation reveals the dominance of polyphenols and their glycosides in the four polyherbal formulations.

  14. The fragmentation pathways of protonated Amiton in the gas phase: towards the structural characterisation of organophosphorus chemical warfare agents by electrospray ionisation tandem mass spectrometry.

    PubMed

    Ellis-Steinborner, Simon; Ramachandran, Aravind; Blanksby, Stephen J

    2006-01-01

    Amiton (O,O-diethyl-S-[2-(diethylamino)ethyl] phosphorothiolate), otherwise known as VG, is listed in schedule 2 of the Chemical Weapons Convention (CWC) and has a structure closely related to VX (O-ethyl-S-(2-diisopropylamino)ethylmethylphosphonothiolate). Fragmentation of protonated VG in the gas phase was performed using electrospray ionisation ion trap mass spectrometry (ESI-ITMS) and revealed several characteristic product ions. Quantum chemical calculations provide the most probable structures for these ions as well as the likely unimolecular mechanisms by which they are formed. The decomposition pathways predicted by computation are consistent with deuterium-labeling studies. The combination of experimental and theoretical data suggests that the fragmentation pathways of VG and analogous organophosphorus nerve agents, such as VX and Russian VX, are predictable and thus ESI tandem mass spectrometry is a powerful tool for the verification of unknown compounds listed in the CWC.

  15. Novel characterisation of minor α-linolenic acid isomers in linseed oil by gas chromatography and covalent adduct chemical ionisation tandem mass spectrometry.

    PubMed

    Gómez-Cortés, P; Brenna, J T; Lawrence, P; de la Fuente, M A

    2016-06-01

    Discrimination between polyunsaturated fatty acid isomers with three double bonds is a great challenge, due to structural similarities and similar polarities. In this study, we report the identification of four minor geometrical isomers of α-linolenic acid (ALA) present in linseed oil samples: (9E,12Z,15E)-, (9Z,12Z,15E)-, (9Z,12E,15Z)- and (9E,12Z,15Z)-octadeca-9,12,15-trienoic acids, chromatographically resolved by gas chromatography (GC) using a new and highly polar ionic phase column (SLB-IL111). Gas chromatography-electron ionisation mass spectrometry (GC-EIMS) determined that the four unknown compounds were C18:3 n-3 isomers. The positional 9-12-15 C18:3 configuration was achieved by covalent adduct chemical ionisation tandem mass spectrometry (CACI-MS/MS) while geometrical configuration was established with analytical standards based on relative retention. We hypothesised that these isomers are formed during linseed oil deodorisation and postulate preferred and unfavoured isomerisation pathways of ALA.

  16. Importance of direct anthropogenic emissions of formic acid measured by a chemical ionisation mass spectrometer (CIMS) during the Winter ClearfLo Campaign in London, January 2012

    NASA Astrophysics Data System (ADS)

    Bannan, Thomas J.; Bacak, Asan; Muller, Jennifer B. A.; Booth, A. Murray; Jones, Benjamin; Le Breton, Michael; Leather, Kimberley E.; Ghalaieny, Mohamed; Xiao, Ping; Shallcross, Dudley E.; Percival, Carl J.

    2014-02-01

    Formic acid, an ubiquitous trace gas in the atmosphere, was measured using a chemical ionisation mass spectrometer (CIMS) during the winter ClearfLo campaign in London, 2012. Daily calibrations of formic acid gave sensitivities of 3 ion counts s-1 pptv-1 for the complete campaign and a limit of detection of 2 ppt. No correlation with nitric acid was observed, R2 of 0.137, indicating no significant secondary source of formic acid. However, a strong positive correlation with NOx, CO, and production in line with rush hour periods indicated a direct anthropogenic emission of formic acid from vehicle emissions. Peaks of 6.7 ppb of formic acid were observed with a mean of 610 ppt. Global models indicated that this emission source dominates in the northern hemisphere where global models underestimate formic acid most significantly, thus increasing the accuracy of modelling of global formic acid emissions.

  17. Characterisation of chemical components for identifying historical Chinese textile dyes by ultra high performance liquid chromatography - photodiode array - electrospray ionisation mass spectrometer.

    PubMed

    Han, Jing; Wanrooij, Jantien; van Bommel, Maarten; Quye, Anita

    2017-01-06

    This research makes the first attempt to apply Ultra High Performance Liquid Chromatography (UHPLC) coupled to both Photodiode Array detection (PDA) and Electrospray Ionisation Mass Spectrometer (ESI-MS) to the chemical characterisation of common textile dyes in ancient China. Three different extraction methods, respectively involving dimethyl sulfoxide (DMSO)-oxalic acid, DMSO and hydrochloric acid, are unprecedentedly applied together to achieve an in-depth understanding of the chemical composition of these dyes. The first LC-PDA-MS database of the chemical composition of common dyes in ancient China has been established. The phenomena of esterification and isomerisation of the dye constituents of gallnut, gardenia and saffron, and the dye composition of acorn cup dyed silk are clarified for the first time. 6-Hydroxyrubiadin and its glycosides are first reported on a dyed sample with Rubia cordifolia from China. UHPLC-PDA-ESI-MS with a C18 BEH shield column shows significant advantages in the separation and identification of similar dye constituents, particularly in the cases of analysing pagoda bud and turmeric dyed sample extracts.

  18. Simultaneous determination of 16 brominated flame retardants in food and feed of animal origin by fast gas chromatography coupled to tandem mass spectrometry using atmospheric pressure chemical ionisation.

    PubMed

    Bichon, E; Guiffard, I; Vénisseau, A; Lesquin, E; Vaccher, V; Brosseaud, A; Marchand, P; Le Bizec, B

    2016-08-12

    A gas chromatography tandem mass spectrometry method using atmospheric pressure chemical ionisation was developed for the monitoring of 16 brominated flame retardants (7 usually monitored polybromodiphenylethers (PBDEs) and BDE #209 and 8 additional emerging and novel BFRs) in food and feed of animal origin. The developed analytical method has decreased the run time by three compared to conventional strategies, using a 2.5m column length (5% phenyl stationary phase, 0.1mm i.d., 0.1μmf.t.), a pulsed split injection (1:5) with carrier gas helium flow rate at 0.48mLmin(-1) in one run of 20 min. For most BFRs, analytical data were compared with the current analytical strategy relying on GC/EI/HRMS (double sector, R=10000 at 10% valley). Performances in terms of sensitivity were found to meet the Commission recommendation (118/2014/EC) for nBFRs. GC/APCI/MS/MS represents a promising alternative for multi-BFRs analysis in complex matrices, in that it allows the monitoring of a wider list of contaminants in a single injection and a shorter run time.

  19. On-line measurements of α-pinene ozonolysis products using an atmospheric pressure chemical ionisation ion-trap mass spectrometer

    NASA Astrophysics Data System (ADS)

    Warscheid, Bettina; Hoffmann, Thorsten

    An on-line technique to investigate complex organic oxidation reactions in environmental chamber experiments is presented. The method is based on the direct introduction of the chamber air into an atmospheric pressure ion source of a commercial ion-trap mass spectrometer. To demonstrate the analytical potential of the method (atmospheric pressure chemical ionisation/mass spectrometry, APCI/MS), the ozonolysis of α-pinene was investigated in a series of experiments performed in various sized reaction chambers at atmospheric pressure and 296 K in synthetic air. Investigations were focussed on the influence of the water vapour concentration on the formation of the predominant oxidation product, pinonaldehyde, derived from the α-pinene/ozone reaction. Quantification of pinonaldehyde was achieved by conducting a standard addition technique. The molar yield of pinonaldehyde was found to depend strongly on the actual water vapour concentration between <1 and 80% relative humidity. Starting with an average yield of 0.23±0.05 at dry conditions, pinonaldehyde formation was approximately doubled by reaching a yield of 0.53±0.05 at a relative humidity of around 60%. Furthermore, the formation mechanism of pinonaldehyde was investigated in greater detail using isotopically labelled water. Applying on-line APCI/MS, pinonaldehyde formation under incorporation of 18O was observed, strongly supporting the reaction of the stabilised Criegee radical with water in the gas phase as suggested by Alvarado et al. (Journal of Geophysical Research 103 (1998) 25541-25551). Furthermore, the mass spectra recorded on-line were used to perform a semi-quantitative estimation of the decomposition pathway of the primary ozonide, indicating a branching ratio of 0.35/0.65.

  20. Application of positive ion chemical ionisation and tandem mass spectrometry combined with gas chromatography to the trace level analysis of ethyl carbamate in bread.

    PubMed

    Hamlet, Colin G; Jayaratne, Sanal M; Morrison, Carol

    2005-01-01

    A rapid, sensitive and selective method has been developed and validated for the analysis of the contaminant ethyl carbamate (EC) in bread products at the part-per-billion level. The new procedure uses positive ion chemical ionisation (PICI) and tandem mass spectrometry (MS/MS), combined with gas chromatography (GC), on a 'bench-top' triple-quadrupole mass spectrometer. Ammonia was the PICI reagent gas of choice because of its ability to produce abundant [M+H]+ and [M+NH4]+ ions from EC and deuterium-labelled EC (LEC) used as an internal standard. For identification and quantification, selected reaction monitoring (SRM) was used to follow the precursor-to-product ion transitions of m/z 107 --> 90, m/z 107 --> 62 and m/z 90 --> 62 for EC, as well as m/z 112 --> 63 for the LEC internal standard. The limits of detection and quantification were 0.6 and 1.2 microg kg(-1), respectively, and the recovery of the method was 101 +/- 10% at 10 microg kg(-1) and 98 +/- 5% at 100 microg kg(-1). The precision of the method, established under conditions of intermediate reproducibility, did not exceed a relative standard deviation of 7%. The quantitative performance of the new GC/PICI-SRM procedure compared favourably with that of a reference method based on GC/MS and selected ion monitoring (correlation coefficient, r = 0.997). However, the new method had the advantages of reduced sample preparation time, improved sensitivity and unambiguous identification of EC at all concentrations. Application of the new method to the analysis of 50 UK breads showed that levels of EC ranged from 0.6 to 2.3 microg kg(-1) in retail products and from 3.1 to 12.2 microg kg(-1) for breads prepared using domestic breadmaking machines (dry weight basis). Toasting bread in a domestic toaster led to increases of between two- and three-fold in mean EC concentrations.

  1. An improved dispersive solid-phase extraction clean-up method for the gas chromatography-negative chemical ionisation tandem mass spectrometric determination of multiclass pesticide residues in edible oils.

    PubMed

    Deme, Pragney; Azmeera, Tirupathi; Prabhavathi Devi, B L A; Jonnalagadda, Padmaja R; Prasad, R B N; Vijaya Sarathi, U V R

    2014-01-01

    An improved sample preparation using dispersive solid-phase extraction clean-up was proposed for the trace level determination of 35 multiclass pesticide residues (organochlorine, organophosphorus and synthetic pyrethroids) in edible oils. Quantification of the analytes was carried out by gas chromatography-mass spectrometry in negative chemical ionisation mode (GC-NCI-MS/MS). The limit of detection and limit of quantification of residues were in the range of 0.01-1ng/g and 0.05-2ng/g, respectively. The analytes showed recoveries between 62% and 110%, and the matrix effect was observed to be less than 25% for most of the pesticides. Crude edible oil samples showed endosulfan isomers, p,p'-DDD, α-cypermethrin, chlorpyrifos, and diazinon residues in the range of 0.56-2.14ng/g. However, no pesticide residues in the detection range of the method were observed in refined oils.

  2. Impact ionisation mass spectrometry of polypyrrole-coated pyrrhotite microparticles

    NASA Astrophysics Data System (ADS)

    Hillier, Jon K.; Sternovsky, Zoltan; Armes, Steven P.; Fielding, Lee A.; Postberg, Frank; Bugiel, Sebastian; Drake, Keith; Srama, Ralf; Kearsley, Anton T.; Trieloff, Mario

    2014-07-01

    Cation and anion impact ionization mass spectra of polypyrrole-coated pyrrhotite cosmic dust analogue particles are analysed over a range of cosmically relevant impact speeds. Spectra with mass resolutions of 150-300 were generated by hypervelocity impacts of charged particles, accelerated to up to 37 km s-1 in a Van de Graaff electrostatic accelerator, onto a silver target plate in the Large Area Mass Analyzer (LAMA) spectrometer. Ions clearly indicative of the polypyrrole overlayer are identified at masses of 93, 105, 117, 128 and 141 u. Organic species, predominantly derived from the thin (20 nm) polypyrrole layer on the surface of the particles, dominate the anion spectra even at high (>20 km s-1) impact velocities and contribute significantly to the cation spectra at velocities lower than this. Atomic species from the pyrrhotite core (Fe and S) are visible in all spectra at impact velocities above 6 km s-1 for 56Fe+, 9 km s-1 for 32S+ and 16 km s-1 for 32S- ions. Species from the pyrrhotite core are also frequently visible in cation spectra at impact speeds at which surface ionisation is believed to dominate (<10 km s-1), although the large number of organic peaks complicates the identification of characteristic molecular species. A thin oxidised surface layer on the pyrrhotite particles is indicated by weak spectral features assigned to iron oxides and iron oxy-hydroxides, although the definitive identification of sulfates and hydrated sulfates from the oxidation process was not possible. Silver was confirmed as an excellent choice for the target plate of an impact ionization mass spectrometer, as it provided a unique isotope signature for many target-projectile cluster peaks at masses above 107-109 u. The affinity of Ag towards a dominant organic fragment ion (CN-) derived from fragmentation of the polypyrrole component led to molecular cluster formation. This resulted in an enhanced sensitivity to a particular particle component, which may be of great use

  3. Investigation, by single photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS), of the effect of different cigarette-lighting devices on the chemical composition of the first cigarette puff.

    PubMed

    Adam, Thomas; Baker, Richard R; Zimmermann, Ralf

    2007-01-01

    Soft single-photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS) has been used to investigate the effect of different cigarette-lighting devices on the chemical composition of the mainstream smoke from the first cigarette puff. Lighting devices examined were a Borgwaldt electric lighter, a propane/butane gas lighter, a match, a candle, and the burning zone of another cigarette. To eliminate the effects of the different masses of tobacco burnt by use of the different lighting methods a normalisation procedure was performed which enabled investigation of changes in the chemical patterns of the resulting smoke. When another cigarette was used as the lighting device, elevated levels of ammonia and other nitrogen-containing substances were observed. These are high in the sidestream smoke of the cigarette used for lighting and would be drawn into the mainstream smoke of the cigarette being lit. In contrast, smoke from the cigarette lit by the electric lighter contained slightly higher normalised amounts of isoprene. Lighting the cigarette by use of a candle resulted in larger amounts of substances, e.g. benzene, which most probably originated from thermal decomposition of wax. The composition of the first puff of smoke obtained by use of the three lighting methods with open flames (gas lighter, match, and candle) was usually similar whereas the composition of the smoke produced by use of the electric lighter and the cigarette as the lighter were more unique. The chemical patterns generated by the different lighting devices could, however, be separated by principal-component analyses. Two additional test series were also studied. In the first the cigarette was lit with an electric lighter, then extinguished, the ash was cut off, and the cigarette was re-lit. In the second the cigarette was heated in an oven to 80 degrees C for 5 min before being lit. These treatments did not result in changes in the chemical composition compared with cigarettes lit in the

  4. Forensic applications of desorption electrospray ionisation mass spectrometry (DESI-MS).

    PubMed

    Morelato, Marie; Beavis, Alison; Kirkbride, Paul; Roux, Claude

    2013-03-10

    Desorption electrospray ionisation mass spectrometry (DESI-MS) is an emerging analytical technique that enables in situ mass spectrometric analysis of specimens under ambient conditions. It has been successfully applied to a large range of forensically relevant materials. This review assesses and highlights forensic applications of DESI-MS including the analysis and detection of illicit drugs, explosives, chemical warfare agents, inks and documents, fingermarks, gunshot residues and drugs of abuse in urine and plasma specimens. The minimal specimen preparation required for analysis and the sensitivity of detection achieved offer great advantages, especially in the field of forensic science.

  5. Improved method for the determination of zinc pyrithione in environmental water samples incorporating on-line extraction and preconcentration coupled with liquid chromatography atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Bones, Jonathan; Thomas, Kevin V; Paull, Brett

    2006-11-03

    A method has been developed for the determination of zinc pyrithione (ZnPT) in environmental water samples using monolithic reversed-phase silica columns for rapid on-line large volume solid phase extraction in tandem with on-line matrix removal using sacrificial strong anion exchange (SAX) columns. This is coupled with reversed-phase liquid chromatography with atmospheric pressure chemical ionisation mass spectrometric detection. Limits of detection in spiked river water samples, using a 200 mL preconcentration volume, were determined as 18 ng L(-1), with a limit of quantitation of 62 ng L(-1). The percentage recovery from spiked river water was found to be 72+/-9 (n=3 extractions), whilst overall method precision, following 10 repeat complete analyses was found to be 27% RSD at 1 microg L(-1). Linearity was determined over the concentration range of 0.25-10 microg L(-1) and the calculated regression coefficient was R(2)=0.9802. The method was used to investigate the environmental fate of zinc pyrithione in waters and its partition coefficient between sediment and water phases.

  6. Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography-mass spectrometry with negative ion chemical ionisation.

    PubMed

    Albinet, A; Leoz-Garziandia, E; Budzinski, H; Viilenave, E

    2006-07-14

    This study deals with the development of a routine analytical method using gas chromatography-mass spectrometry with negative ion chemical ionisation (GC/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of this analytical procedure has been performed on standard reference material (SRM 1649a: urban dust), giving results in good agreement with the few data available in the literature. The analytical method was also applied on ambient air samples (on both gas and particulate phases) from the French POVA program (POllution des Vallées Alpines). NPAHs concentrations observed for a rural site during the Winter period are about 0.2-100.0pgm(-3) in the particulate phase and about 0.0-20.0pgm(-3) in the gas phase. OPAHs present concentrations 10-100 times higher (0.1-2.0ngm(-3) and 0.0-1.4ngm(-3) for the particulate and the gas phases, respectively). These preliminary results show a good correlation between the characteristics of the sampling site and the compound origins (primary or secondary).

  7. Rapid isolation of biomarkers for compound specific radiocarbon dating using high-performance liquid chromatography and flow injection analysis-atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Smittenberg, Rienk H; Hopmans, Ellen C; Schouten, Stefan; Sinninghe Damsté, Jaap S

    2002-11-29

    Repeated semi-preparative normal-phase HPLC was performed to isolate selected biomarkers from sediment extracts for radiocarbon analysis. Flow injection analysis-mass spectrometry was used for rapid analysis of collected fractions to evaluate the separation procedure, taking only 1 min per fraction. In this way 100-1000 microg of glycerol dialkyl glycerol tetraethers, sterol fractions and chlorophyll-derived phytol were isolated from typically 100 g of marine sediment, i.e., in sufficient quantities for radiocarbon analysis, without significant carbon isotopic fractionation or contamination.

  8. Extraction of maleic hydrazide residues from potato crisps and their determination using high-performance liquid chromatography with UV and atmospheric pressure chemical ionisation mass spectrometric detection.

    PubMed

    Lewis, D J; Barnes, K A; Wilkinson, K; Thorpe, S A; Reynolds, S L; Startin, J R

    1996-10-25

    A method was required for the determination of maleic hydrazide residues in potato crisps. A published method for the extraction of the analyte from onions and potatoes was evaluated and found to be inappropriate due to the inability of the extracting solvent to penetrate the oily matrix. A method was developed to overcome this problem; the resulting recovery data (mean = 92.9%, R.S.D. = 8.3%, n = 16) confirmed its efficiency, and was used to analyse 48 retail potato crisp samples. To confirm possible residues identified by screening with HPLC-UV, an HPLC-atmospheric pressure chemical ionization MS method was developed. There was good agreement between the data obtained from the two detection techniques (R2 = 0.978, slope = 1.11).

  9. Atmospheric pressure chemical ionisation mass spectrometry analysis linked with chemometrics for food classification - a case study: geographical provenance and cultivar classification of monovarietal clarified apple juices.

    PubMed

    Gan, Heng-Hui; Soukoulis, Christos; Fisk, Ian

    2014-03-01

    In the present work, we have evaluated for first time the feasibility of APCI-MS volatile compound fingerprinting in conjunction with chemometrics (PLS-DA) as a new strategy for rapid and non-destructive food classification. For this purpose 202 clarified monovarietal juices extracted from apples differing in their botanical and geographical origin were used for evaluation of the performance of APCI-MS as a classification tool. For an independent test set PLS-DA analyses of pre-treated spectral data gave 100% and 94.2% correct classification rate for the classification by cultivar and geographical origin, respectively. Moreover, PLS-DA analysis of APCI-MS in conjunction with GC-MS data revealed that masses within the spectral ACPI-MS data set were related with parent ions or fragments of alkyesters, carbonyl compounds (hexanal, trans-2-hexenal) and alcohols (1-hexanol, 1-butanol, cis-3-hexenol) and had significant discriminating power both in terms of cultivar and geographical origin.

  10. Differential ionisation of natural antioxidant polyenes in electrospray and nanospray mass spectrometry.

    PubMed

    Guaratini, Thais; Gates, Paul J; Pinto, Ernani; Colepicolo, Pio; Lopes, Norberto P

    2007-01-01

    Carotenoids are natural products with high economic relevance for the pharmaceutical industries and are a common subject for biochemical research. Reported here is a comparative study of the ionisation of carotenoids by electrospray mass spectrometry (ESI-MS) and nanospray mass spectrometry (nanoESI-MS). The results demonstrate that, along with solvent choice, the influence of the different ionisation processes of ESI and nanoESI are fundamental in determining how ionisation is achieved and which ions (molecular ion or protonated molecule) are observed in MS. The increased understanding afforded by this study will help in the development of unequivocal microanalytical methods for carotenoids and related antioxidant polyenes.

  11. High ionisation absorption in low mass X-ray binaries

    NASA Astrophysics Data System (ADS)

    Ponti, G.; Bianchi, S.; Muñoz-Darias, T.; De, K.; Fender, R.; Merloni, A.

    2016-05-01

    The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and narrow absorption features, sporadically present in the X-ray spectra of some systems, are actually the signature of equatorial outflows, which might carry away more matter than that being accreted. Therefore, they play a major role in the accretion phenomenon. These outflows (or ionised atmospheres) are ubiquitous during the softer states but absent during the power-law dominated, hard states, suggesting a strong link with the state of the inner accretion disc, presence of the radio-jet and the properties of the central source. Here, we discuss the current understanding of this field.

  12. Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry.

    PubMed

    Hashir, Muhammad Ahsan; Stecher, Guenther; Bakry, Rania; Kasemsook, Saowapak; Blassnig, Bernhard; Feuerstein, Isabel; Abel, Gudrun; Popp, Michael; Bobleter, Ortwin; Bonn, Guenther K

    2007-01-01

    Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material.

  13. A Carbon Nano Tube electron impact ionisation source for low-power, compact spacecraft mass spectrometers

    NASA Astrophysics Data System (ADS)

    Sheridan, S.; Bardwell, M. W.; Morse, A. D.; Morgan, G. H.

    2012-04-01

    A novel ionisation source which uses commercially available Carbon Nano Tube devices is demonstrated as a replacement for a filament based ionisation source in an ion trap mass spectrometer. The carbon nanotube ion source electron emission was characterised and exhibited typical emission of 30 ± 1.7 μA with an applied voltage differential of 300 V between the carbon nanotube tips and the extraction grid. The ion source was tested for longevity and operated under a condition of continuous emission for a period of 44 h; there was an observed reduction in emission current of 26.5% during operation. Spectra were generated by installing the ion source into a Finnigan Mat ITD700 ion trap mass spectrometer; the spectra recorded showed all of the characteristic m/z peaks from m/z 69 to m/z 219. Perfluorotributylamine spectra were collected and averaged contiguously for a period of 48 h with no significant signal loss or peak mass allocation shift. The low power requirements and low mass of this novel ionisation source are considered be of great value to future space missions where mass spectrometric technology will be employed.

  14. Peroxyacetyl nitrate (PAN) and peroxyacetic acid (PAA) measurements by iodide chemical ionisation mass spectrometry: first analysis of results in the boreal forest and implications for the measurement of PAN fluxes

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; Pouvesle, N.; Thieser, J.; Schuster, G.; Axinte, R.; Fischer, H.; Williams, J.; Lelieveld, J.; Crowley, J. N.

    2013-02-01

    We describe measurements of peroxyacetyl nitrate (CH3C(O)O2NO2, PAN) and peroxyacetic acid (CH3C(O)OOH, PAA) in the Boreal forest using iodide chemical ionization mass spectrometry (ICIMS). The measurements were made during the Hyytiälä United Measurement of Photochemistry and Particles - Comprehensive Organic Particle and Environmental Chemistry (HUMPPA-COPEC-2010) measurement intensive. Mixing ratios of PAN and PAA were determined by measuring the acetate ion signal (CH3C(O)O-, m/z = 59) resulting from reaction of CH3C(O)O2 (from the thermal dissociation of PAN) or CH3C(O)OOH with iodide ions using alternatively heated and ambient temperature inlet lines. During some periods of high temperature (~ 30 °C) and low NOx (< 1 ppbv), PAA mixing ratios were similar to, or exceeded those of PAN and thus contributed a significant fraction of the total acetate signal. PAA is thus a potential interference for ICIMS measurements of PAN, and especially eddy covariance flux measurements in environments where the PAA flux is likely to be a significant proportion of the (short timescale) acetate ion variability. Within the range of mixing ratios of NOx measured during HUMPPA-COPEC, the modelled ratio of PAA-to-PAN was found to be sensitive to temperature (through the thermal decomposition rate of PAN) and the HO2 mixing ratio, thus providing some constraint to estimates of photochemical activity and oxidation rates in the Boreal environment.

  15. Peroxyacetyl nitrate (PAN) and peroxyacetic acid (PAA) measurements by iodide chemical ionisation mass spectrometry: first analysis of results in the boreal forest and implications for the measurement of PAN fluxes

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; Pouvesle, N.; Thieser, J.; Schuster, G.; Axinte, R.; Fischer, H.; Williams, J.; Lelieveld, J.; Crowley, J. N.

    2012-08-01

    We describe measurements of peroxyacetyl nitrate (CH3C(O)O2NO2, PAN) and peroxyacetic acid (CH3C(O)OOH, PAA) in the Boreal forest using iodide chemical ionization mass spectrometry (ICIMS). The measurements were made during the Hyytiälä United Measurement of Photochemistry and Particles - Comprehensive Organic Particle and Environmental Chemistry (HUMPPA-COPEC-2010) measurement intensive. Mixing ratios of PAN and PAA were determined by measuring the acetate ion signal (CH3C(O)O2-, m/z 59) resulting from reaction of CH3C(O)O2 (from the thermal dissociation of PAN) or CH3C(O)OOH with iodide ions using alternatively heated and ambient temperature inlet lines. During conditions of high temperature and low NOx, PAA mixing ratios were similar to, or exceeded those of PAN and thus contributed a significant fraction of the total acetate signal. PAA is thus a potential interference for ICIMS measurements of PAN, and especially eddy covariance flux measurements in environments where the PAA flux is likely to be a significant proportion of the short timescale acetate ion variability. Within the range of mixing ratios of NOx measured during HUMPPA-COPEC, the ratio of PAA-to-PAN was found to be sensitive to temperature (through the thermal decomposition rate of PAN) and the HO2 mixing ratio, thus providing some constraint to estimates of photochemical activity and oxidation rates in the Boreal environment.

  16. Measuring technique for thermal ionisation mass spectrometry of human tracer kinetic study with stable cerium isotopes.

    PubMed

    Keiser, Teresa; Höllriegl, Vera; Giussani, Augusto; Oeh, Uwe

    2011-06-01

    Thermal ionisation mass spectrometry (TIMS) method has been developed for the simultaneous detection of different cerium isotopes in biological samples (i.e., blood and urine) at very low concentrations. The work has been done in the frame of a biokinetic study, where different stable cerium isotopes have been administered orally and intravenously as tracers to the human body. In order to develop an appropriate detection method for the tracers in the biological samples, an optimum sample preparation technique has been set and adapted to the specific requirements of the analysis technique used, i.e., TIMS. For sample evaporation and ionisation, the double tantalum filament technique showed the best results. The ions produced were simultaneously collected on a secondary electron multiplier so that the isotopic ratios of the cerium isotopes in the biological samples could be measured. The technique has been optimised for the determination of cerium down to 1 ng loaded on the evaporation filament corresponding to cerium concentrations of down to 1 ng ml(-1) in the blood or urine samples. It has been shown that the technique is reliable in application and enables studies on cerium metabolism and biokinetics in humans without employing radioactive tracers.

  17. Headspace analysis of new psychoactive substances using a Selective Reagent Ionisation-Time of Flight-Mass Spectrometer

    PubMed Central

    Acton, W. Joe; Lanza, Matteo; Agarwal, Bishu; Jürschik, Simone; Sulzer, Philipp; Breiev, Kostiantyn; Jordan, Alfons; Hartungen, Eugen; Hanel, Gernot; Märk, Lukas; Mayhew, Chris A.; Märk, Tilmann D.

    2014-01-01

    The rapid expansion in the number and use of new psychoactive substances presents a significant analytical challenge because highly sensitive instrumentation capable of detecting a broad range of chemical compounds in real-time with a low rate of false positives is required. A Selective Reagent Ionisation-Time of Flight-Mass Spectrometry (SRI-ToF-MS) instrument is capable of meeting all of these requirements. With its high mass resolution (up to m/Δm of 8000), the application of variations in reduced electric field strength (E/N) and use of different reagent ions, the ambiguity of a nominal (monoisotopic) m/z is reduced and hence the identification of chemicals in a complex chemical environment with a high level of confidence is enabled. In this study we report the use of a SRI-ToF-MS instrument to investigate the reactions of H3O+, O2+, NO+ and Kr+ with 10 readily available (at the time of purchase) new psychoactive substances, namely 4-fluoroamphetamine, methiopropamine, ethcathinone, 4-methylethcathinone, N-ethylbuphedrone, ethylphenidate, 5-MeO-DALT, dimethocaine, 5-(2-aminopropyl)benzofuran and nitracaine. In particular, the dependence of product ion branching ratios on the reduced electric field strength for all reagent ions was investigated and is reported here. The results reported represent a significant amount of new data which will be of use for the development of drug detection techniques suitable for real world scenarios. PMID:25844048

  18. Resonance ionisation mass spectrometry of krypton and its applications in planetary science

    NASA Astrophysics Data System (ADS)

    Strashnov, I.; Gilmour, J. D.

    2014-06-01

    A new resonance ionisation time-of-flight mass spectrometer for determining krypton isotope ratios in extraterrestrial samples is presented. Laser heating is used to extract gas from mg-size samples. A cryogenic sample concentrator is employed. Atoms continuously condense on a 75 K stainless steel substrate at the back plate of a Wiley-McLaren laser ion source from where they are desorbed by a pulsed 1064 nm laser and resonantly ionized in the plume. A three-colour (116.5 nm, 558.1 nm and 1064 nm) excitation scheme is used. Tuneable coherent Vacuum Ultraviolet (vuv) radiation near 116.5 nm is generated by four-wave sum frequency mixing of 252.5 nm and 1507 nm pulsed dye laser beams in a binary mixture of negatively and positively dispersive gases (Xe and Ar). Isotope effects have been observed that reduce the reproducibility of isotope ratio measurements between odd-mass, non-zero nuclear spin isotopes and even-mass, zero nuclear spin isotopes. This can be minimised and stabilised by controlling the laser fluences, experimental geometry, and the population of the magnetic sub-levels of the excited atomic states used in the ionisation process. Once stability is achieved, sample-standard bracketing (during which the known isotope ratios of a standard are determined before and after the measurements of the sample under the same conditions) allows precision and reproducibility of 1 % for the major isotope ratios to be achieved in samples krypton atoms. Detection limits of atoms/isotope have been demonstrated, ratios of Kr in meteorites have been made with 5-10 % precision. Applications of the instrument in various areas of planetary science are also discussed.

  19. Free energy for blue copper protein unfolding determined by electrospray ionisation mass spectrometry.

    PubMed

    Cunsolo, V; Foti, S; La Rosa, C; Saletti, R; Canters, G W; Verbeet, M P

    2001-01-01

    An electrospray ionisation (ESI) mass spectrometric method for the determination of the free energy (DeltaG) of unfolding of proteins is described. The method was tested using three blue copper proteins: wild type azurin, Cys-3Ala/Cys-26Ala (C3A/C26A) azurin mutant and wild-type amicyanin. The time course of the denaturation process of the proteins dissolved in methanol/water (50:50, v/v, pH 3.5) was followed by recording ESI mass spectra at time intervals. The spectra showed two series of peaks, corresponding to the native holo-protein and the unfolded apo-protein. From the intensity ratio of these two series of peaks at increasing time and at equilibrium, the free energy for the unfolding process for the three proteins could be determined. To evaluate the reliability of the thermodynamic data obtained by the ESI mass spectrometric approach, the denaturation process was followed by UV-VIS spectroscopy. The two sets of data obtained by these independent methods were in good agreement indicating that the ESI-MS approach can be used to obtain reliable quantitative information about the protein unfolding process. In principle, this approach can be applied to other proteins and requires very low amounts of sample, due to the intrinsic sensitivity of mass spectrometry. This may prove particularly useful when the amount of sample available prevents the use of current methods.

  20. The use of particle beam mass spectrometry for the measurement of impurities in a nabumetone drug substance, not easily amenable to atmospheric pressure ionisation techniques.

    PubMed

    Wolff, J C; Hawtin, P N; Monté, S; Balogh, M; Jones, T

    2001-01-01

    Liquid chromatography/particle beam mass spectrometry (LC/PB-MS) was used for the structural elucidation of some impurities in nabumetone as this compound poorly ionises by atmospheric pressure ionisation (API) techniques. PB-MS was optimised for nabumetone and a sensitivity study was carried out. To obtain full scan electron ionisation spectra a minimum of 100 ng of compound on column was needed. By using 20 mg/mL solutions of nabumetone, impurities at levels of about 250 ppm mass fraction relative to nabumetone could be detected. Results were compared with LC/API-MS and previous GC/MS.

  1. Screening for medium chain acyl-CoA dehydrogenase deficiency using electrospray ionisation tandem mass spectrometry

    PubMed Central

    Clayton, P.; Doig, M.; Ghafari, S.; Meaney, C.; Taylor, C.; Leonard, J.; Morris, M.; Johnson, A.

    1998-01-01

    OBJECTIVE—To establish criteria for the diagnosis of medium chain acyl-CoA dehydrogenase (MCAD) deficiency in the UK population using a method in which carnitine species eluted from blood spots are butylated and analysed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS).
DESIGN—Four groups were studied: (1) 35 children, aged 4 days to 16.2 years, with proven MCAD deficiency (mostly homozygous for the A985G mutation, none receiving carnitine supplements); (2) 2168control children; (3) 482 neonates; and (4) 15 MCAD heterozygotes.
RESULTS—All patients with MCAD deficiency had an octanoylcarnitine concentration ([C8-Cn]) > 0.38 µM and no accumulation of carnitine species > C10 or < C6. Among the patients with MCAD deficiency, the [C8-Cn] was significantly lower in children > 10 weeks old and in children with carnitine depletion (free carnitine < 20 µM). Neonatal blood spots from patients with MCAD deficiency had a [C8-Cn] > 1.5 µM, whereas in heterozygotes and other normal neonates the [C8-Cn] was < 1.0 µM. In contrast, the blood spot [C8-Cn] in eight of 27 patients with MCAD deficiency > 10 weeks old fell within the same range as five of 15 MCAD heterozygotes (0.38-1.0 µM). However, the free carnitine concentrations were reduced (< 20 µM) in the patients with MCAD deficiency but normal in the heterozygotes.
CONCLUSIONS—Criteria for the diagnosis of MCAD deficiency using ESI-MS/MS must take account of age and carnitine depletion. If screening is undertaken at 7-10 days, the number of false positive and negative results should be negligible. Because there have been no instances of death or neurological damage following diagnosis of MCAD deficiency in our patient group, a strong case can be made for neonatal screening for MCAD deficiency in the UK.

 PMID:9797589

  2. Capillary electrophoresis with electrospray ionisation-mass spectrometry for the characterisation of degradation products in aged papers.

    PubMed

    Dupont, Anne-Laurence; Seemann, Agathe; Lavédrine, Bertrand

    2012-01-30

    A methodology for capillary electrophoresis/electrospray ionisation mass spectrometry (CE/ESI-MS) was developed for the simultaneous analysis of degradation products from paper among two families of compounds: low molar mass aliphatic organic acids, and aromatic (phenolic and furanic) compounds. The work comprises the optimisation of the CE separation and the ESI-MS parameters for improved sensitivity with model compounds using two successive designs of experiments. The method was applied to the analysis of lignocellulosic paper at different stages of accelerated hygrothermal ageing. The compounds of interest were identified. Most of them could be quantified and several additional analytes were separated.

  3. Spectrometre de masse a ionisation Penning selective: Elimination des corrections necessaires a la determination du rapport isotopique de l'hydrogene

    NASA Astrophysics Data System (ADS)

    Letarte, Sylvain

    Dans le but d'ameliorer la precision avec laquelle le rapport isotopique de l'hydrogene peut etre determine, un spectrometre de masse a ionisation Penning a ete construit pour provoquer l'ionisation selective de l'hydrogene moleculaire et de l'hydrure de deuterium a partir d'un melange gazeux. L'utilisation d'atomes dans des etats d'excitation metastable s'est averee une solution adequate pour reponde a cette attente. L'emploi de l'helium, a l'interieur d'une source d'atomes metastables construit specifiquement pour ce travail, ne permet pas d'obtenir un spectre de masse compose uniquement des deux molecules d'interet. L'ionisation de ces dernieres provient de deux processus distincts, soient l'ionisation Penning et l'ionisation par bombardement electronique. Contrairement a l'helium, il a ete demontre que le neon metastable est un candidat ideal pour produire l'ionisation selective de type Penning. Le nombre d'ions produits est directement proportionnel au courant de la decharge electrique et de la pression d'operation de la source d'atomes metastables. Ces resultats demontrent le potentiel d'un tel spectrometre de masse pour ameliorer la precision a laquelle le rapport isotopique peut etre determine comparativement aux autres techniques existantes.

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

    PubMed

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

    2013-01-01

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

  5. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida.

    PubMed

    Cameron, Simon J S; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-11-14

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities.

  6. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) Provides Accurate Direct from Culture Species Identification within the Genus Candida

    PubMed Central

    Cameron, Simon J. S.; Bolt, Frances; Perdones-Montero, Alvaro; Rickards, Tony; Hardiman, Kate; Abdolrasouli, Alireza; Burke, Adam; Bodai, Zsolt; Karancsi, Tamas; Simon, Daniel; Schaffer, Richard; Rebec, Monica; Balog, Julia; Takáts, Zoltan

    2016-01-01

    Members of the genus Candida, such as C. albicans and C. parapsilosis, are important human pathogens. Other members of this genus, previously believed to carry minimal disease risk, are increasingly recognised as important human pathogens, particularly because of variations in susceptibilities to widely used anti-fungal agents. Thus, rapid and accurate identification of clinical Candida isolates is fundamental in ensuring timely and effective treatments are delivered. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has previously been shown to provide a high-throughput platform for the rapid and accurate identification of bacterial and fungal isolates. In comparison to commercially available matrix assisted laser desorption ionisation time of flight mass spectrometry (MALDI-ToF), REIMS based methods require no preparative steps nor time-consuming cell extractions. Here, we report on the ability of REIMS-based analysis to rapidly and accurately identify 153 clinical Candida isolates to species level. Both handheld bipolar REIMS and high-throughput REIMS platforms showed high levels of species classification accuracy, with 96% and 100% of isolates classified correctly to species level respectively. In addition, significantly different (FDR corrected P value < 0.05) lipids within the 600 to 1000 m/z mass range were identified, which could act as species-specific biomarkers in complex microbial communities. PMID:27841356

  7. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  8. Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

    PubMed Central

    Rudd, David; Benkendorff, Kirsten; Voelcker, Nicolas H.

    2015-01-01

    Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. PMID:25786067

  9. Determination and imaging of metabolites from Vitis vinifera leaves by laser desorption/ionisation time-of-flight mass spectrometry.

    PubMed

    Hamm, Gregory; Carré, Vincent; Poutaraud, Anne; Maunit, Benoît; Frache, Gilles; Merdinoglu, Didier; Muller, Jean-François

    2010-02-01

    Analysis of grapevine phytoalexins at the surface of Vitis vinifera leaves has been achieved by laser desorption/ionisation time-of-flight mass spectrometry (LDI-ToFMS) without matrix deposition. This simple and rapid sampling method was successfully applied to map small organic compounds at the surface of grapevine leaves. It was also demonstrated that the laser wavelength is a highly critical parameter. Both 266 and 337 nm laser wavelengths were used but the 266 nm wavelength gave increased spatial resolution and better sensitivity for the detection of the targeted metabolites (resveratrol and linked stilbene compounds). Mass spectrometry imaging of grapevine Cabernet Sauvignon leaves revealed specific locations with respect to Plasmopara viticola pathogen infection or light illumination.

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

    PubMed

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

    2016-09-01

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

  11. Thermally annealed gold nanoparticles for surface-assisted laser desorption ionisation-mass spectrometry of low molecular weight analytes.

    PubMed

    Pilolli, Rosa; Ditaranto, Nicoletta; Di Franco, Cinzia; Palmisano, Francesco; Cioffi, Nicola

    2012-10-01

    Metal nanomaterials have an emerging role in surface-assisted laser desorption ionisation-mass spectrometry (SALDI-MS) providing a useful tool to overcome some limitations intrinsically related to the use of conventional organic matrices in matrix-assisted LDI-MS. In this contribution, the possibility to use a stainless-steel-supported gold nanoparticle (AuNP) film as a versatile platform for SALDI-MS was assessed. A sacrificial anode electrosynthetic route was chosen in order to obtain morphologically controlled core-shell AuNPs; the colloidal AuNPs were, thereafter, drop cast onto a stainless-steel sample plate and the resulting AuNP film was thermally annealed in order to improve its effectiveness as LDI-MS promoter. Spectroscopic characterization of the nanostructured film by X-ray photoelectron spectroscopy was crucial for understanding how annealing induced changes in the surface chemistry and influenced the performance of AuNPs as desorption/ionisation promoter. In particular, it was demonstrated that the post-deposition treatments were essential to enhance the AuNP core/analyte interaction, thus resulting in SALDI-MS spectra of significantly improved quality. The AuNP films were applied to the detection of three different classes of low molecular weight (LMW) analytes, i.e. amino acids, peptides and LMW polymers, in order to demonstrate the versatility of this nanostructured material.

  12. Thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry using particle suspension matrices.

    PubMed

    Crecelius, Anna; Clench, Malcolm R; Richards, Don S; Parr, Vic

    2002-06-07

    Particle suspension matrices have been successfully utilized for the analysis of tetracycline antibiotics by thin-layer chromatography-matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (TLC-MALDI-TOF-MS). Particles of different materials and sizes have been investigated (Co-UFP, TiN, TiO2, Graphite and Silicon) by applying particle suspensions to eluted TLC plates. Mass spectra and mass chromatograms have been recorded directly from the TLC plates. Strong cationization by sodium and potassium was obtained in the positive ion mode, with [M+Na-NH3]+ ions being the predominant signals. The TLC-MALDI mass spectra recorded from graphite suspensions showed the lowest background noise and the highest peak intensities from the range of suspension matrices studied. The mass accuracy from graphite films was improved by adding the peptide Phe-Phe to the graphite suspensions. This allowed internal recalibration of the TLC-MALDI mass spectra acquired during a run. One major potential advantage of TLC-MALDI-TOF-MS has been demonstrated in the analysis of chlortetracycline and tetracycline in a mixture of oxytetracycline, chlortetracycline, tetracycline and minocycline. Examination of the TLC plate prior to MALDI analysis showed only an unresolved spot for chlortetracycline and tetracycline. However by investigation of the MALDI mass spectra and plotting of single ion chromatograms separate peaks for chlortetracycline and tetracycline could be obtained.

  13. Determination of potato glycoalkaloids using high-pressure liquid chromatography-electrospray ionisation/mass spectrometry.

    PubMed

    Matsuda, Fumio; Morino, Keiko; Miyazawa, Haruna; Miyashita, Masahiro; Miyagawa, Hisashi

    2004-01-01

    A method for quantifying two toxic glycoalkaloids, alpha-solanine and alpha-chaconine, in potato (Solanum tuberosum) tuber tissue was developed using HPLC-electrospray ionisation (ESI)/MS. Potato samples were extracted with 5% aqueous acetic acid, and the extracts were subjected directly to HPLC-ESI/MS after filtration. By determining the intensities of the protonated molecules of alpha-solanine (m/z 868) and alpha-chaconine (m/z 852) using selected ion monitoring (positive ion mode), a sensitive assay was attained with detection limits of 38 and 14 ppb for the two glycoalkaloids, respectively. The high sensitivity and selectivity of MS detection effectively reduced the time of analysis thus enabling a high throughput assay of glycoalkaloids in potato tubers.

  14. The detection of piroxicam, tenoxicam and their metabolites in equine urine by electrospray ionisation ion trap mass spectrometry.

    PubMed

    McKinney, Andrew R; Suann, Craig J; Stenhouse, Allen M

    2004-01-01

    An investigation has been conducted into the metabolism and urinary excretion of orally administered piroxicam and tenoxicam in the horse. The major component detected in urine after the administration of piroxicam was 5'-hydroxypiroxicam, which was detectable up to 24 h post-administration. Unchanged piroxicam was present only as a minor component. In contrast, unchanged tenoxicam was the major component observed after the administration of tenoxicam, being detectable for 72 h post-administration, while 5'-hydroxytenoxicam was a minor component. Phase II beta-glucuronide conjugation in each case was found to be negligible. The ion trap mass spectral characteristics of piroxicam, tenoxicam, 5'-hydroxypiroxicam and 5'-hydroxytenoxicam under electrospray ionisation conditions were examined in some detail.

  15. Determination of Cd and Zn by isotope dilution-thermal ionisation mass spectrometry using a sequential analysis procedure.

    PubMed

    Ayoub, Ahmed S; McGaw, Brian A; Midwood, Andrew J

    2002-05-16

    Isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) was used to examine the certified Cd and Zn content of 4 Certified Reference Materials (CRMs); 2 soils: GBW07401 and GBW07405, 1 plant CRM060 and an animal tissue SRM1566a. The CRMs were chosen to be of contrasting origin and Cd:Zn content. Three digestion procedures were compared: (i) an open tube aqua regia procedure (ii) microwave digestion using Teflon bombs and (iii) hydrofluoric acid (HF) digestion using PTFE bombs. The Cd and Zn levels obtained using ID-TIMS all fell within the published certified range for the CRMs. This was the case regardless of the digestion procedure used, although HF digestion tended to yield marginally higher levels than the other procedures and in one instance, Cd in GBW07401, was significantly different (P<0.05) from the certified range. A filament loading procedure was developed, to allow sequential analysis of Cd and Zn on the same single filament during thermal ionisation mass spectrometry analysis. The sequential analysis technique was evaluated to ensure that Zn did not fractionate during Cd analysis and there was no inter-element interference. No marked difference in the precision and accuracy of the isotope ratio measurements were obtained from sequential element analyses on the same filament when compared to individual element analyses for a range of standard solutions or for sample digests. The most efficient procedure in terms of costs and productivity for future work of this kind would be a combination of microwave digestion and sequential analysis of Cd and Zn on the same filament.

  16. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

    NASA Astrophysics Data System (ADS)

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-02-01

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research.

  17. Real-time analysis of organic compounds in ship engine aerosol emissions using resonance-enhanced multiphoton ionisation and proton transfer mass spectrometry.

    PubMed

    Radischat, Christian; Sippula, Olli; Stengel, Benjamin; Klingbeil, Sophie; Sklorz, Martin; Rabe, Rom; Streibel, Thorsten; Harndorf, Horst; Zimmermann, Ralf

    2015-08-01

    Organic combustion aerosols from a marine medium-speed diesel engine, capable to run on distillate (diesel fuel) and residual fuels (heavy fuel oil), were investigated under various operating conditions and engine parameters. The online chemical characterisation of the organic components was conducted using a resonance-enhanced multiphoton ionisation time-of-flight mass spectrometer (REMPI TOF MS) and a proton transfer reaction-quadrupole mass spectrometer (PTR-QMS). Oxygenated species, alkenes and aromatic hydrocarbons were characterised. Especially the aromatic hydrocarbons and their alkylated derivatives were very prominent in the exhaust of both fuels. Emission factors of known health-hazardous compounds (e.g. mono- and poly-aromatic hydrocarbons) were calculated and found in higher amounts for heavy fuel oil (HFO) at typical engine loadings. Lower engine loads lead in general to increasing emissions for both fuels for almost every compound, e.g. naphthalene emissions varied for diesel fuel exhaust between 0.7 mg/kWh (75 % engine load, late start of injection (SOI)) and 11.8 mg/kWh (10 % engine load, late SOI) and for HFO exhaust between 3.3 and 60.5 mg/kWh, respectively. Both used mass spectrometric techniques showed that they are particularly suitable methods for online monitoring of combustion compounds and very helpful for the characterisation of health-relevant substances. Graphical abstract Three-dimensional REMPI data of organic species in diesel fuel and heavy fuel oil exhaust.

  18. Visualisation of abscisic acid and 12-oxo-phytodienoic acid in immature Phaseolus vulgaris L. seeds using desorption electrospray ionisation-imaging mass spectrometry

    PubMed Central

    Enomoto, Hirofumi; Sensu, Takuya; Sato, Kei; Sato, Futoshi; Paxton, Thanai; Yumoto, Emi; Miyamoto, Koji; Asahina, Masashi; Yokota, Takao; Yamane, Hisakazu

    2017-01-01

    The plant hormone abscisic acid (ABA) and the jasmonic acid related-compound 12-oxo-phytodienoic acid (OPDA) play crucial roles in seed development, dormancy, and germination. However, a lack of suitable techniques for visualising plant hormones has restricted the investigation of their biological mechanisms. In the present study, desorption electrospray ionisation-imaging mass spectrometry (DESI-IMS), a powerful tool for visualising metabolites in biological tissues, was used to visualise ABA and OPDA in immature Phaseolus vulgaris L. seed sections. The mass spectra, peak values and chemical formulae obtained from the analysis of seed sections were consistent with those determined for ABA and OPDA standards, as were the precursor and major fragment ions observed in tandem mass spectrometry (MS/MS) imaging. Furthermore, the precursor and fragment ion images showed similar distribution patterns. In addition, the localisation of ABA and OPDA using DESI-IMS was confirmed using liquid chromatography-MS/MS (LC-MS/MS). The results indicated that ABA was mainly distributed in the radical and cotyledon of the embryo, whereas OPDA was distributed exclusively in external structures, such as the hilum and seed coat. The present study is the first to report the visualisation of plant hormones using IMS, and demonstrates that DESI-IMS is a promising technique for future plant hormone research. PMID:28211480

  19. Mass Transfer with Chemical Reaction.

    ERIC Educational Resources Information Center

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  20. Fragmentation of mycosporine-like amino acids by hydrogen/deuterium exchange and electrospray ionisation tandem mass spectrometry.

    PubMed

    Cardozo, Karina H M; Carvalho, Valdemir M; Pinto, Ernani; Colepicolo, Pio

    2006-01-01

    The determination and identification of mycosporine-like amino acids (MAAs) from algae remain a major challenge due to the low concentration. Mass spectrometry (MS) can make an invaluable contribution in the search and identification of MAAs because of its high sensitivity, possibility of coupling with liquid chromatography, and the availability of powerful tandem mass spectrometric techniques. However, the unequivocal determination of the presence and location of important functional groups present on the basic skeleton of the MAAs is often elusive due to their inherent instability under MS conditions. In this study, the use of hydrogen/deuterium (H/D) exchange and electrospray ionisation tandem mass spectrometry (ESI-MS/MS) for characterisation of four MAAs (palythine, asterina, palythinol and shinorine) isolated from the macroalgae Gracilaria tenuistipitata Chang et Xia was investigated. The accurate-mass confirmation of the protonated molecules was performed on a Q-TOF instrument. We demonstrate that employing deuterium labelling in ESI-MS/MS analysis provides a convenient tool for the determination of new MAAs. Although the fragmentation patterns of MAAs were discussed earlier, to our knowledge, this is the first time that mechanisms are proposed.

  1. Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography-atmospheric pressure ionisation mass spectrometry.

    PubMed

    Zöllner, Peter; Mayer-Helm, Bernhard

    2006-12-15

    Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006.

  2. Characterisation of a proposed internet synthesis of N,N-dimethyltryptamine using liquid chromatography/electrospray ionisation tandem mass spectrometry.

    PubMed

    Martins, Cláudia P B; Freeman, Sally; Alder, John F; Brandt, Simon D

    2009-08-14

    The psychoactive properties of N,N-dimethyltryptamine (DMT) are known to induce altered states of consciousness in humans. These properties attract great interest from clinical, neuroscientific, clandestine and forensic communities. The Breath of Hope Synthesis was reported on an internet website as a convenient two-step methodology for the preparation of DMT. The analytical characterisation of the first stage was the subject of previous publications by the authors and involved the thermal decarboxylation of tryptophan and the formation of tryptamine. The present study reports on the characterisation of the second step of this procedure which was based on the methylation of tryptamine. This employed methyl iodide and benzyltriethylammonium chloride/sodium hydroxide as a phase transfer catalyst. The reaction product was characterised by liquid chromatography/electrospray ionisation tandem mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry. Quantitative evaluation was carried out in positive multiple reaction monitoring mode (MRM), which included synthesis of the identified reaction products. MRM screening of the product did not lead to the detection of DMT. Instead, 11.1% tryptamine starting material, 21.0% N,N,N-trimethyltryptammonium iodide (TMT) and 47.4% 1-N-methyl-TMT were detected. A 0.5% trace of the monomethylated N-methyltryptamine was also detected. This study demonstrated the impact on product purity of doubtful synthetic methodologies discussed on the internet.

  3. Confirmation and 3D profiling of anabolic steroid esters in injection sites using imaging desorption electrospray ionisation (DESI) mass spectrometry.

    PubMed

    de Rijke, Eva; Hooijerink, Dick; Sterk, Saskia S; Nielen, Michel W F

    2013-01-01

    In this study, desorption electrospray ionisation (DESI) linear ion trap tandem mass spectrometry (MS(n)) was applied for the confirmation and three-dimensional profiling of anabolic steroid esters in an injection site of bovine muscle. The spatial resolution of the DESI-MS(n) was demonstrated by scanning hormone esters and marker ink lines drawn at various distances on a microscopic slide at set distances, using an x-scanner with manual y and z adjustment. Tissue slices of bovine muscle injected with a hormone cocktail were analysed. All anabolic steroid esters could be directly detected in the sample and confirmed on the basis of identification points awarded for selected MS/MS transitions according to the performance criteria given in Commission Decision 2002/657/EC. Moreover, the injection site could be mapped by two-dimensional and three-dimensional imaging MS, showing a horizontal and vertical distribution through the muscle tissue. This DESI approach offers potential for analysis of injection sites of steroid esters from illegally treated animals; moreover, direct analysis by ambient imaging DESI-MS still allows conventional extraction and analysis of the whole tissue for further confirmatory or contra-analysis afterwards.

  4. Direct analysis of pharmaceutical tablet formulations using Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging.

    PubMed

    Earnshaw, Caroline J; Carolan, Vikki A; Richards, Don S; Clench, Malcolm R

    2010-06-15

    Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) has been used to directly analyse a range of tablets in order to assess the homogeneity of the active drug compound throughout the excipients contained within the tablets studied. The information gained from the imaging experiments can be used to improve and gain a greater understanding of the manufacturing process; such knowledge will enable improvements in finished product quality to make safer and more efficacious tablet formulations. Commercially available and prescription tablet formulations have been analysed, including aspirin, paracetamol, sildenafil citrate (Viagra(R)) and a batch of tablets in development (tablet X: placebo; 1 mg; 3 mg and 6 mg). MALDI MSI provides semi-quantitative information that is related to ion abundance, therefore Principal Component Analysis (PCA), a multivariate analysis technique, has been used to differentiate between tablets containing different amounts of active drug ingredient. Aspects of sample preparation have also been investigated with regard to tablet shape and texture. The results obtained indicate that MALDI MSI can be used effectively to analyse the spatial distribution of the active pharmaceutical component (API) in pharmaceutical tablet formulations.

  5. Determination of chlorinated paraffins in sediments from the Firth of Clyde by gas chromatography with electron capture negative ionisation mass spectrometry and carbon skeleton analysis by gas chromatography with flame ionisation detection.

    PubMed

    Hussy, Ines; Webster, Lynda; Russell, Marie; Moffat, Colin

    2012-07-01

    Short chain chlorinated paraffins (SCCPs) are a group of persistent organic pollutants (POPs) of increasing concern, but are to date not widely investigated in the environment, largely due to the challenges involved in their quantification. Here, SCCPs were quantified in marine sediments from the Firth of Clyde, Scotland, by gas chromatography with electron capture negative ionisation mass spectrometry (GC-ECNIMS) and through carbon skeleton analysis by gas chromatography with flame ionisation detection (GC-FID), and the analytical challenges encountered are discussed. Concentrations in the sediments ranged from 0.4 to 69 μg kg(-1) when determined by GC-ECNIMS, and from 5.6 to 379 μg kg(-1) when determined by GC-FID. For 8 out of 11 samples, analysis by GC-FID gave higher results than analysis by GC-ECNIMS. Unexpected aspects of the analysis, such as the presence of high concentrations of longer chain chlorinated paraffins in the samples, are also presented.

  6. Determination of pharmaceutical compounds in skin by imaging matrix-assisted laser desorption/ionisation mass spectrometry.

    PubMed

    Bunch, Josephine; Clench, Malcolm R; Richards, Don S

    2004-01-01

    Matrix-assisted laser desorption/ionisation (MALDI) quadrupole time-of-flight mass spectrometry (Q-TOFMS) has been used to detect and image the distribution of a xenobiotic substance in skin. Porcine epidermal tissue was treated with 'Nizoral', a medicated shampoo containing ketoconazole (+/-)-1-acetyl-4-[p-[[(2R,4S)-2-(2,4-dichlorophenyl)-2-(imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) as active ingredient. Following incubation for 1 h at 37 degrees C all excess formulation was washed from the surface. A cross-section of the drug-treated tissue was then blotted onto a cellulose membrane, precoated in matrix (alpha-cyano-4-hydroxycinnamic acid (CHCA)), by airspray deposition. In separate experiments the tissue surface was treated with Nizoral within a triangular former, and subsequently blotted onto a matrix-coated membrane. Sample membranes were then mounted into the recess of specialised MALDI targets with adhesive tape. All samples were analysed by MALDI-TOFMS using an Applied Biosystem 'Q-star Pulsar i' hybrid Q-TOF mass spectrometer fitted with an orthagonal MALDI ion source and imaging software. Detection of the protonated molecule was readily achievable by this technique. Treatment of the tissue within a template gave rise to images depicting the expected distribution of the drug, demonstrating that this technique is capable of producing spatially useful data. Ion images demonstrating the permeation of the applied compound into the skin were achieved by imaging a cross-sectional imprint of treated tissue. A calibration graph for the determination of ketoconazole was prepared using the sodium adduct of the matrix ion as an internal standard. This enabled construction of a quantitative profile of drug in skin. Conventional haematoxylin and eosin staining and microscopy methods were employed to obtain a histological image of the porcine epidermal tissue. Superimposing the mass spectrometric and histological images appeared to indicate drug

  7. Detection of phenolic oxidation products in cider apple juice by high-performance liquid chromatography electrospray ionisation ion trap mass spectrometry.

    PubMed

    Bernillon, S; Guyot, S; Renard, C M G C

    2004-01-01

    Juice was prepared from cider apples of the cultivar "Kermerrien" under oxidative conditions. After isolation by solid-phase extraction, the phenolic fraction was subjected to high-performance liquid chromatography/electrospray ionisation mass spectrometry. SIM scans were performed at m/z values obtained in model solutions. The oxidation products, resulting from coupling between a molecule of caffeoylquinic acid and caffeoylquinic acid, catechin or dimeric flavan-3-ol, were detected.

  8. Analysis of nitroaromatic compounds in complex samples using solid-phase microextraction and isotope dilution quantification gas chromatography-electron-capture negative ionisation mass spectrometry.

    PubMed

    Jönsson, S; Gustavsson, L; van Bavel, B

    2007-09-14

    A solid-phase microextraction (SPME) method using gas chromatography-electron-capture negative ionisation mass spectrometry (GC-ECNI-MS) and isotope dilution quantification for the analysis of nitroaromatic compounds in complex, water based samples has been optimised. For ionisation, ECNI was the most sensitive and selective method. SPME was compared to solid-phase extraction (SPE) and found to be more sensitive for these small volume samples. LODs were in the range 0.02-38ngL(-1) for SPME and 6-184ngL(-1) for SPE, respectively. The SPME method was applied on samples in the ngL(-1) level from artificial reed beds treated with sludge containing residues from explosives and pharmaceuticals.

  9. Identification of amino acids by material enhanced laser desorption/ionisation mass spectrometry (MELDI-MS) in positive- and negative-ion mode

    NASA Astrophysics Data System (ADS)

    Hashir, Muhammad Ahsan; Stecher, Guenther; Mayr, Stefan; Bonn, Guenther K.

    2009-01-01

    In the present study, different silica gel modifications were evaluated for their application as target surface for material enhanced laser desorption/ionisation mass spectrometric (MELDI-MS) investigation of amino acids. 4,4'-Azodianiline (ADA-silica) modified silica gel was successfully employed for the qualitative analysis of amino acids in positive- and in negative-ion mode. Further no derivatisation of amino acids was necessary, as the introduced system allowed the direct analysis of targets and delivered spectra with excellent signal intensity and signal-to-noise ratio within a few minutes. The influence of surface chemistry, ionisation mode and the nature of analytes on signal intensity was studied and discussed. Detection limit of 2.10 pg (10 fmol) was achieved by employing ADA-silica in positive-ion mode. Finally, xylem saps from different types of trees were analysed. This proved the high performance and excellent behaviour of the introduced target surface material.

  10. Rapid identification of additives in poly(vinyl chloride) lid gaskets by direct analysis in real time ionisation and single-quadrupole mass spectrometry.

    PubMed

    Rothenbacher, Thorsten; Schwack, Wolfgang

    2010-01-01

    Gaskets for lids of glass jars usually consist of poly(vinyl chloride) (PVC) containing plasticisers and additional additives, which may migrate into packed foodstuffs. To conform to legal regulations, any such migration has to be determined analytically, which is a big challenge due to the huge chemical variety of additives in use. Therefore, a rapid screening method by means of direct analysis in real time mass spectrometry (DART-MS), using a single-quadrupole mass spectrometer, was developed. On introducing a plastisol sample into the DART interface, protonated molecules and ammonium adducts were obtained as the typical ionisation products of any additives present, and cleavages of ester bonds as typical fragmentation processes. Generally, additives present in the 1% range could be directly and easily identified if ion suppressive effects deriving from specific molecules did not occur. These effects could be avoided by analysing toluene extracts of plastisol samples, and this also improved the sensitivity. Using this method, it was possible to identify phthalates, fatty acid amides, tributyl O-acetylcitrate, dibutyl sebacate, bis(2-ethylhexyl) adipate, 1,2-diisononyl 1,2-cyclohexanedicarboxylate, and even more complex additives like acetylated mono- and diacylglycerides, epoxidised soybean oil, and polyadipates, with a limit of detection of < or = 1% in PVC plastisols. Only in the case of epoxidised linseed oil were levels of > or = 5% required for identification. The detection of azodicarbonamide, used as a foaming agent within the manufacturing process, was possible in principle, but was not highly reproducible due to the very low concentrations in plastisols.

  11. Characterisation of poly(alkyl methacrylate)s by means of electrospray ionisation-tandem mass spectrometry (ESI-MS/MS)

    NASA Astrophysics Data System (ADS)

    Jackson, Anthony T.; Slade, Susan E.; Scrivens, James H.

    2004-11-01

    Electrospray ionisation-tandem mass spectrometry (ESI-MS/MS) has been employed for the characterisation of two poly(alkyl methacrylate) polymers, namely poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PBMA). Collision-induced dissociation (CID) experiments were performed in a quadrupole orthogonal time-of-flight (ToF) tandem mass spectrometer fitted with a nanospray source. Tandem mass spectra from singly, doubly and triply charged precursor ions (with alkali metals used for cationisation of the oligomers) are shown and the data are compared to those previously generated by means of matrix-assisted laser desorption/ionisation-collision-induced dissociation (MALDI-CID). These data indicate that cations with greater ionic radii may yield the most useful structural information as the mass-to-charge ratio of the precursor ion increases, whereas lithium or sodium ions are proposed to be ideal for obtaining spectra from lower molecular weight oligomers. Fragment ions at low mass-to-charge ratios dominate the spectra. Two series of peaks may be used to calculate the masses of the initiating and terminating end groups of the polymer. Ion peaks of greater mass-to-charge ratios form series that may be used to infer sequence information from the polymers.

  12. Determination and separation of bisphenol A, phthalate metabolites and structural isomers of parabens in human urine with conventional high-pressure liquid chromatography combined with electrospray ionisation tandem mass spectrometry.

    PubMed

    Myridakis, Antonis; Balaska, Eirini; Gkaitatzi, Christina; Kouvarakis, Antonis; Stephanou, Euripides G

    2015-03-01

    Phthalates, bisphenol A (BPA) and parabens (PBs), organic chemicals widely used in everyday products, are considered to be endocrine disruptors. We propose a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of seven phthalate metabolites, six PBs and BPA in human urine. All three categories of the above endocrine disruptors were simultaneously extracted from 1 mL of human urine using solid phase extraction. In addition, with a conventional reversed phase LC column, we achieved for the first time the separation of three pairs of structural isomers, namely iso-/n-butyl paraben, propyl paraben and monobutyl phthalate. LC-MS/MS was operated and tested in both electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI). ESI was selected for the analysis due to its superior stability and repeatability. The method limit of detection (mLOD), achieved for a single set of high-performance LC conditions, ranged from 0.01 to 0.84 ng/mL for phthalate metabolites, from 0.06 to 0.24 ng/mL for PBs and was 2.01 ng/mL for BPA. Derivatisation of BPA with dansyl chloride lowered its mLOD to 0.007 ng/mL. Blank contamination was non-detectable. The present method was successfully applied for the analysis of the above-mentioned compounds in 80 male human urine samples.

  13. Mass-sensitive chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Adkins, Douglas R.; Lewis, Patrick R.

    2007-01-30

    A microfabricated mass-sensitive chemical preconcentrator actively measures the mass of a sample on an acoustic microbalance during the collection process. The microbalance comprises a chemically sensitive interface for collecting the sample thereon and an acoustic-based physical transducer that provides an electrical output that is proportional to the mass of the collected sample. The acoustic microbalance preferably comprises a pivot plate resonator. A resistive heating element can be disposed on the chemically sensitive interface to rapidly heat and release the collected sample for further analysis. Therefore, the mass-sensitive chemical preconcentrator can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  14. Towards monitoring real-time cellular response using an integrated microfluidics-matrix assisted laser desorption ionisation/nanoelectrospray ionisation-ion mobility-mass spectrometry platform.

    PubMed

    Enders, J R; Marasco, C C; Kole, A; Nguyen, B; Sevugarajan, S; Seale, K T; Wikswo, J P; McLean, J A

    2010-11-01

    The combination of microfluidic cell trapping devices with ion mobility-mass spectrometry offers the potential for elucidating in real time the dynamic responses of small populations of cells to paracrine signals, changes in metabolite levels and delivery of drugs and toxins. Preliminary experiments examining peptides in methanol and recording the interactions of yeast and Jurkat cells with their superfusate have identified instrumental set-up and control parameters and online desalting procedures. Numerous initial experiments demonstrate and validate this new instrumental platform. Future outlooks and potential applications are addressed, specifically how this instrumentation may be used for fully automated systems biology studies of the significantly interdependent, dynamic internal workings of cellular metabolic and signalling pathways.

  15. A miniaturised electron ionisation time-of-flight mass spectrometer that uses a unique helium ion removal pulsing technique specifically for gas analysis.

    PubMed

    Qing, Jiang; Huang, Zhengxu; Zhang, Yan; Zhu, Hui; Tan, Guobin; Gao, Wei; Yang, Peng-yuan

    2013-06-21

    A miniaturised reflectron time-of-flight mass spectrometer combined with an electron ionisation ion source has been developed for the analysis of gases. An entirely new helium ion removal pulsing technique in this mass spectrometer is used to achieve an improved performance for the first time. The helium carrier gas, which enters into the source along with the gaseous sample, is simultaneously ionised and then orthogonally introduced into the time-of-fight mass analyser. Once the relatively light helium ions in the ion packet become extremely close to the reflectron plate (B-plate for short in this article), a modulated pulse is instantaneously applied on the B-plate and a negative reflectron voltage is set to the B-plate and lasts for a very short period, during which all the helium ions are directly bumped into the B-plate and subsequently removed. The helium ion removal pulsing technique can efficiently avoid saturation of the micro-channel plate caused by too many helium ions. A compact and durable instrument is designed, which has a mass resolving resolution greater than 400 FWHM for online gas analysis. The technology may also be further developed to remove other ions for TOF mass spectrometry.

  16. Oligomeric carbon and siloxane series observed by matrix-assisted laser desorption/ionisation and laser desorption/ionisation mass spectrometry during the analysis of soot formed in fuel-rich flames.

    PubMed

    Apicella, Barbara; Ciajolo, Anna; Millan, Marcos; Galmes, Carolina; Herod, Alan A; Kandiyoti, Rafael

    2004-01-01

    Oligomeric carbon and siloxane series have been observed by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS), during the analysis of the dichloromethane (DCM)-soluble fractions of condensable material recovered from fuel-rich flames. Laser desorption (LD) spectra showed a pattern of oligomeric dimethyl-siloxane structures with a spacing of 74 u. The siloxane series appears to have originated as contamination of samples by silicone oil used to lubricate connections of polymer tubing. This was confirmed by extracting silicone tubing and silicone grease with DCM followed by MALDI-MS analysis. A series of peaks with a mass spacing of 24 u was also observed, superimposed on the continuum of unresolved organic ions. This oligomeric series appears to correspond to polycyclic aromatics separated by (mainly) ethylene bridges. Thus LD-MS appears to have revealed a series of soot precursors, intermediate between polycyclic aromatics and particulate soot, which was not detected by MALDI-MS. More detailed work is necessary to define these species with precision.

  17. Gas-phase dissociation of ionic liquid aggregates studied by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation.

    PubMed

    Fernandes, Ana M; Coutinho, João A P; Marrucho, Isabel M

    2009-01-01

    Positive singly charged ionic liquid aggregates [(C(n)mim)(m+1)(BF(4))(m)](+) (mim = 3-methylimidazolium; n = 2, 4, 8 and 10) and [(C(4)mim)(m+1)(A)(m)](+) (A = Cl(-), BF(4) (-), PF(6) (-), CF(3)SO(3) (-) and (CF(3)SO(2))(2)N(-)) were investigated by electrospray ionisation mass spectrometry and energy-variable collision induced dissociation. The electrospray ionisation mass spectra (ESI-MS) showed the formation of an aggregate with extra stability for m = 4 for all the ionic liquids with the exception of [C(4)mim][CF(3)SO(3)]. ESI-MS-MS and breakdown curves of aggregate ions showed that their dissociation occurred by loss of neutral species ([C(n)mim][A])(a) with a >or= 1. Variable-energy collision induced dissociation of each aggregate from m = 1 to m = 8 for all the ionic liquids studied enabled the determination of E(cm, 1/2) values, whose variation with m showed that the monomers were always kinetically much more stable than the larger aggregates, independently of the nature of cation and anion. The centre-of-mass energy values correlate well with literature data on ionic volumes and interaction and hydrogen bond energies.

  18. Simultaneous determination of selected endocrine disrupters (pesticides, phenols and phthalates) in water by in-field solid-phase extraction (SPE) using the prototype PROFEXS followed by on-line SPE (PROSPEKT) and analysis by liquid chromatography-atmospheric pressure chemical ionisation-mass spectrometry.

    PubMed

    López-Roldán, P; López de Alda, M J; Barceló, D

    2004-02-01

    In this study, a new procedure, based on on-line solid-phase extraction (SPE) and analysis by liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS), has been developed for the simultaneous, multianalyte determination of 21 selected pesticides, phenols and phthalates in water. SPE was carried out on polymeric PLRP-s cartridges by percolating 20 mL-samples. For sample preconcentration, the performance of a prototype programmable field extraction system (PROFEXS) was evaluated against the commercial laboratory bench Prospekt system used for method development. The Profexs is designed for the automated on-site sampling, SPE preconcentration, and storage of up to 16 samples in SPE cartridges. These cartridges are further eluted and on-line analyzed with the Prospekt coupled to the chromatographic system. In the optimized method, where completely on-line SPE-LC-MS analysis of the samples is carried out with the Prospekt in the laboratory, detection limits lower than 100 ng/L, and satisfactory precision (relative standard deviations <25%) and accuracies (recovery percentages >75%) were obtained for most investigated compounds from the analysis of spiked Milli-Q water. The extraction efficiency achieved with the Profexs was comparable to that of the Prospekt for most compounds and somewhat lower for the most apolar analytes, probably due to adsorption on the pump filters. The completely on-line optimized method was applied to the analysis of surface water, ground water and drinking water from a waterworks in Barcelona. Some pesticides and phenols were found in both surface water and groundwater at ng/L or microg/L levels, but not in the final drinking water. Di(2-ethylhexyl)phthalate (DEHP) was present in all samples investigated, including blanks. To the author's knowledge, this is the first work describing the application of a fully automated on-line SPE-LC-MS method for the simultaneous analysis of pesticides, phenols, and

  19. Qualitative analysis of Copaifera oleoresin using comprehensive two-dimensional gas chromatography and gas chromatography with classical and cold electron ionisation mass spectrometry.

    PubMed

    Wong, Yong Foo; Uekane, Thais M; Rezende, Claudia M; Bizzo, Humberto R; Marriott, Philip J

    2016-12-16

    Improved separation of both sesquiterpenes and diterpenic acids in Copaifera multijuga Hayne oleoresin, is demonstrated by using comprehensive two-dimensional gas chromatography (GC×GC) coupled to accurate mass time-of-flight mass spectrometry (accTOFMS). GC×GC separation employs polar phases (including ionic liquid phases) as the first dimension ((1)D) column, combined with a lower polarity (2)D phase. Elution temperatures (Te) of diterpenic acids (in methyl ester form, DAME) increased as the (1)D McReynolds' polarity value of the column phase decreased. Since Te of sesquiterpene hydrocarbons decreased with increased polarity, the very polar SLB-IL111 (1)D phase leads to excessive peak broadening in the (2)D apolar phase due to increased second dimension retention ((2)tR). The combination of SLB-IL59 with a nonpolar column phase was selected, providing reasonable separation and low Te for sesquiterpenes and DAME, compared to other tested column sets, without excessive (2)tR. Identities of DAME were aided by both soft (30eV) electron ionisation (EI) accurate mass TOFMS analysis and supersonic molecular beam ionisation (cold EI) TOFMS, both which providing less fragmentation and increased relative abundance of molecular ions. The inter-relation between EI energies, emission current, signal-to-noise and mass error for the accurate mass measurement of DAME are reported. These approaches can be used as a basis for conducting of GC×GC with soft EI accurate mass measurement of terpenes, particularly for unknown phytochemicals.

  20. Identification of phenolic constituents in red chicory salads (Cichorium intybus) by high-performance liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry.

    PubMed

    Carazzone, Chiara; Mascherpa, Dora; Gazzani, Gabriella; Papetti, Adele

    2013-06-01

    Phenolic acids and flavonoids extracted from several types of Cichorium intybus var. silvestre salads ("Chioggia", "Treviso", "Treviso tardivo", and "Verona") were characterised by high-performance liquid chromatography-electrospray ionisation/mass spectrometry. Among the 64 compounds detected, several hydroxycinnamic acid derivatives including 8 mono- and dicaffeoylquinic acids, 3 tartaric acid derivatives, 31 flavonol and 2 flavone glycosides, as well as 10 anthocyanins were characterised based on UV spectra and MS(n) fragmentation patterns. Furthermore, several isomers of caffeic acid derivatives were distinguished for the first time by their specific mass spectral data. This is the first study reporting the glycosylation type and position of mono- and diglycosylated flavonoids in red salads.

  1. General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri.

    PubMed

    Escher, Beate I; Baumer, Andreas; Bittermann, Kai; Henneberger, Luise; König, Maria; Kühnert, Christin; Klüver, Nils

    2017-03-22

    The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

  2. On-line coupling of a microelectrode array equipped poly(dimethylsiloxane) microchip with an integrated graphite electrospray emitter for electrospray ionisation mass spectrometry.

    PubMed

    Liljegren, Gustav; Dahlin, Andreas; Zettersten, Camilla; Bergquist, Jonas; Nyholm, Leif

    2005-10-01

    A novel method for the manufacturing of microchips for on-chip combinations of electrochemistry (EC) and sheathless electrospray ionisation mass spectrometry (ESI-MS) is described. The technique, which does not require access to clean-room facilities, is based on the incorporation of an array of gold microcoil electrodes into a poly(dimethylsiloxane)(PDMS) microflow channel equipped with an integrated graphite based sheathless ESI emitter. Electrochemical measurements, which were employed to determine the electroactive area of the electrodes and to test the microchips, show that the manufacturing process was reproducible and that the important interelectrode distance in the electrochemical cell could to be adequately controlled. The EC-ESI-MS device was evaluated based on the ESI-MS detection of the oxidation products of dopamine. The results demonstrate that the present on-chip approach enables full potentiostatic control of the electrochemical cell and the attainment of very short transfer times between the electrochemical cell and the electrospray emitter. The transfer times were 0.6 and 1.2 s for flow rates of 1.0 and 0.5 microL min(-1), respectively, while the electrochemical conversion efficiency of the electrochemical cell was found to be 30% at a flow rate of 0.5 microL min(-1). To decouple the electrochemical cell from the ESI-MS high voltage and to increase the user-friendliness, the on-line electrochemistry-ESI-MS experiments were performed using a wireless Bluetooth battery-powered instrument with the chip floating at the potential induced by the ESI high voltage. The described on-chip EC-ESI-MS device can be used for fundamental electrochemical investigations as well as for applications based on the use of electrochemically controlled sample pretreatment, preconcentration and ionisation steps prior to ESI-MS.

  3. Desorption corona beam ionisation (DCBI) mass spectrometry for in-situ analysis of adsorbed phenol in cigarette acetate fiber filter.

    PubMed

    Du, Wen; Tang, Li-Juan; Wen, Jian-Hui; Zhong, Ke-Jun; Jiang, Jian-Hui; Wang, Hua; Chen, Bo; Yu, Ru-Qin

    2015-01-01

    The study of spatial distribution characteristics of the adsorbed compounds for absorbent materials has significant importance in understanding the behaviors of aerosols while they migrating in the absorbent materials. Herein, for the first time, desorption corona beam ionization-mass spectrometry (DCBI-MS) has proposed for direct in-situ analysis of adsorbed aerosol for absorbent materials. DCBI is a novel atmospheric pressure chemical ionization (APCI)-related technique developed by our group in recent years. It can facilitate accurately localizing sampling by forming a visible thin corona beam and avoid the risk of sample contamination and matrix interference compared with other similar techniques. The advantages of DCBI-MS allow rapid screening of the spatial distribution characteristics of the adsorbed compounds for absorbent materials. The distribution characteristic of phenol in cigarette filter tip filled with cellulose acetate fiber was studied as a model case for demonstrating the feasibility of the developed method. As a comparison, conventional HPLC was also used for the study of the distribution characteristic of phenol. The results revealed DCBI-MS had highly improved assay simplicity in spatial distribution characteristic analysis of phenol for the acetate fiber tip, therefore, exhibiting a great potential for convenient, rapid and cost-efficient analysis of the spatial distribution characteristic investigation of adsorbed compounds for adsorbent materials.

  4. Characterisation of ship diesel primary particulate matter at the molecular level by means of ultra-high-resolution mass spectrometry coupled to laser desorption ionisation--comparison of feed fuel, filter extracts and direct particle measurements.

    PubMed

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

    2015-08-01

    In this study, positive-mode laser desorption-ionisation ultra-high-resolution mass spectrometry (LDI-FT-ICR-MS) was applied to study combustion aerosol samples obtained from a ship diesel engine as well as the feed fuel, used to operate the engine. Furthermore, particulate matter was sampled from the exhaust tube using an impactor and analysed directly from the impaction foil without sample treatment. From the high percentage of shared sum formula as well as similarities in the chemical spread of aerosol and heavy fuel oil, results indicate that the primary aerosol mainly consists of survived, unburned species from the feed fuel. The effect of pyrosynthesis could be observed and was slightly more pronounced for the CH-class compared to other compound classes, but in summary not dominant. Alkylation pattern as well as the aromaticity distribution, using the double bond equivalent, revealed a shift towards lower alkylation state for the aerosol. The alkylation pattern of the most dominant series revealed a higher correlation between different aerosol samples than between aerosol and feed samples. This was confirmed by cluster analysis. Overall, this study shows that LDI-FT-ICR-MS can be successfully applied for the analysis of combustion aerosol at the molecular level and that sum formula information can be used to identify chemical differences between aerosol and fuel as well as between different size fractions of the particulate matter.

  5. A study of the analytical behaviour of selected synthetic and naturally occurring quinolines using electrospray ionisation ion trap mass spectrometry, liquid chromatography and gas chromatography and the construction of an appropriate database for quinoline characterisation.

    PubMed

    O'Donnell, F; Ramachandran, V N; Smyth, W F; Hack, C J; Patton, E

    2006-07-14

    Mass spectral fragmentation of quinoline alkaloids of significance in plants has been investigated using electrospray ionisation ion trap mass spectrometry (ESI-MS(n)) with a view to characterisation of molecules of unknown structure isolated from these natural sources. This investigation has led to the generation of an appropriate database incorporating data from ESI-MS(n) and also from gas liquid chromatography (GLC) and liquid chromatography (HPLC) for these low molecular mass quinolines. This has been put to practical application in the identification of quinoline alkaloids in a plant extract. Thus, an acid extraction of the leaves of Choisya ternata containing such tertiary alkaloids was analysed by liquid chromatography-electrospray ionisation mass spectrometry (HPLC-ESI-MS) and the resulting behaviour of the quinolines was compared with that of the quinoline alkaloids in the database.

  6. Binary stars: Mass transfer and chemical composition

    NASA Technical Reports Server (NTRS)

    Lambert, D. L.

    1982-01-01

    It is noted that mass exchange (and mass loss) within a binary system should produce observable changes in the surface chemical composition of both the mass losing and mass gaining stars as a stellar interior exposed to nucleosyntheses is uncovered. Three topics relating mass exchange and/or mass loss to nucleosynthesis are sketched: the chemical composition of Algol systems; the accretion disk of a cataclysmic variable fed by mass from a dwarf secondary star; and the hypothesis that classical Ba II giants result from mass transfer from a more evolved companion now present as a white dwarf.

  7. Examination of the translocation of sulfonylurea herbicides in sunflower plants by matrix-assisted laser desorption/ionisation mass spectrometry imaging.

    PubMed

    Anderson, David M G; Carolan, Vikki A; Crosland, Susan; Sharples, Kate R; Clench, Malcolm R

    2010-11-30

    Pesticides are widely used in agriculture to control weeds, pests and diseases. Successful control is dependent on the compound reaching the target site within the organism after spray or soil application. Conventional methods for determining uptake and movement of herbicides and pesticides include autoradiography, liquid scintillation and chromatographic techniques such as high-performance liquid chromatography (HPLC). Autoradiography using radiolabelled compounds provides the best indication of a compound's movement within the plant system. Autoradiography is an established technique but it relies on the synthesis of radiolabelled compounds. The distribution of four sulfonylurea herbicides in sunflower plants has been studied 24  h after foliar application. The use of matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) images of protonated molecules and fragment ions (resulting from fragmentation at the urea bond within the sulfonylurea herbicides) has provided evidence for translocation above and below the application point. The translocation of nicosulfuron and azoxystrobin within the same plant system has also been demonstrated following their application to the plant stem. This study provides evidence that MALDI-MSI has great potential as an analytical technique to detect and assess the foliar, root and stem uptake of agrochemicals, and to reveal their distribution through the plant once absorbed and translocated.

  8. Fast confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine by LC/MS/MS using negative atmospheric-pressure chemical ionisation (APCI).

    PubMed

    Weinmann, W; Goerner, M; Vogt, S; Goerke, R; Pollak, S

    2001-09-15

    A fast method using automated solid-phase extraction (SPE) and short-column liquid-chromatography coupled to tandem mass-spectrometry (LC/MS/MS) with negative atmospheric-pressure chemical ionisation (APCI) has been developed for the confirmation of 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THC-COOH) in urine samples. This highly specific method which combines chromatographic separation and MS/MS-analysis can be used for the confirmation of positive immunoassay results with a NIDA cut-off of 15ng/ml. The conjugates of THC-COOH were hydrolysed prior to SPE, and a standard SPE was performed using C18-SPE columns. No derivatisation of the extracts was needed as in GC/MS analysis, and the LC run-time was 6.5min by gradient elution with a retention time of 2.4min. Linearity of calibration was obtained in the range between 0 and 500ng/ml (correlation coefficient R(2)=0.998). Using linear regression (0-50ng/ml) the limit of detection (LOD) was 2.0ng/ml and the limit of quantitation (LOQ) was 5.1ng/ml; day-to-day reproducibility and precision were tested at 15 and 250ng/ml and were 13.4ng/ml+/-3.3% and 255.8ng/ml+/-4.5%, respectively.

  9. Airborne laser-spark for ambient desorption/ionisation.

    PubMed

    Bierstedt, Andreas; Riedel, Jens

    2016-01-01

    A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die

  10. Identification of serum proteins discriminating colorectal cancer patients and healthy controls using surface-enhanced laser desorption ionisation-time of flight mass spectrometry

    PubMed Central

    Engwegen, Judith YMN; Helgason, Helgi H; Cats, Annemieke; Harris, Nathan; Bonfrer, Johannes MG; Schellens, Jan HM; Beijnen, Jos H

    2006-01-01

    AIM: To detect the new serum biomarkers for colorectal cancer (CRC) by serum protein profiling with surface-enhanced laser desorption ionisation - time of flight mass spectrometry (SELDI-TOF MS). METHODS: Two independent serum sample sets were analysed separately with the ProteinChip technology (set A: 40 CRC + 49 healthy controls; set B: 37 CRC + 31 healthy controls), using chips with a weak cation exchange moiety and buffer pH 5. Discriminative power of differentially expressed proteins was assessed with a classification tree algorithm. Sensitivities and specificities of the generated classification trees were obtained by blindly applying data from set A to the generated trees from set B and vice versa. CRC serum protein profiles were also compared with those from breast, ovarian, prostate, and non-small cell lung cancer. RESULTS: Mass-to-charge ratios (m/z) 3.1×103, 3.3×103, 4.5×103, 6.6×103 and 28×103 were used as classifiers in the best-performing classification trees. Tree sensitivities and specificities were between 65% and 90%. Most of these discriminative m/z values were also different in the other tumour types investigated. M/z 3.3×103, main classifier in most trees, was a doubly charged form of the 6.6×103-Da protein. The latter was identified as apolipoprotein C-I. M/z 3.1×103 was identified as an N-terminal fragment of albumin, and m/z 28×103 as apolipoprotein A-I. CONCLUSION: SELDI-TOF MS followed by classification tree pattern analysis is a suitable technique for finding new serum markers for CRC. Biomarkers can be identified and reproducibly detected in independent sample sets with high sensitivities and specificities. Although not specific for CRC, these biomarkers have a potential role in disease and treatment monitoring. PMID:16570345

  11. Chemical Mass Balance (CMB) Model

    EPA Pesticide Factsheets

    The EPA-CMB Version 8.2 uses source profiles and speciated ambient data to quantify source contributions. Contributions are quantified from chemically distinct source-types rather than from individual emitters.

  12. Fast monitoring of motor exhaust components by resonant multi-photon ionisation and time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Franzen, Jochen; Frey, Rüdiger; Nagel, Holger

    1995-03-01

    A new analytical procedure is provided by the combination of two types of spectroscopy. Resonant ionization of selected compounds by multiphoton ionization is based on results of absorption spectroscopy for the compound molecules of interest and time-of-flight mass spectrometry serves for the unambigious detection of these compounds. An interesting application of this method is the fast exhaust gas analysis. In the development of future combustion engines, the management of dynamic motor processes becomes predominant because by more than 90 % of all the dangerous exhaust pollutions are produced in instationary motor phases such as fast speed or load changes. The investigation of dynamic processes however, requires fast analytical procedures with millisecond time resolution together with the capability to measure individual components in a very complex gas mixture The objectives for a development project of such an instrument were set by the Research Association for Combustion Engines (Forschungsvereinigung Verbrennungskraftmaschinen, FVV, Germany): Up to ten substances should be monitored synchroneously with a time resolution of about 10 milliseconds, with concentration limits of 1 part per million and with a precision better than 10 % relative standard deviation. Such a laser mass spectrometer for fast multi-component automotive exhaust analyses has been developed in a joint research project by Bruker-Franzen Analytik GmbH, Dornier GmbH and the Technical University of Munich. The system has been applied at a motor test facility to investigate the emissions of the aromatic hydrocarbons benzene, toluene and xylene, of nitric oxide and acetaldehyde in stationary and dynamic engine operation. These measurements demonstrate that strong emission of these pollutants takes place at instationary engine operation and in particular that these compounds are emitted at different times, giving new information about the processes in the combustion chamber and in the exhaust pipe.

  13. Feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) networking in university hospitals in Brussels.

    PubMed

    Martiny, D; Cremagnani, P; Gaillard, A; Miendje Deyi, V Y; Mascart, G; Ebraert, A; Attalibi, S; Dediste, A; Vandenberg, O

    2014-05-01

    The mutualisation of analytical platforms might be used to address rising healthcare costs. Our study aimed to evaluate the feasibility of networking a unique matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) system for common use in several university hospitals in Brussels, Belgium. During a one-month period, 1,055 successive bacterial isolates from the Brugmann University Hospital were identified on-site using conventional techniques; these same isolates were also identified using a MALDI-TOF MS system at the Porte de Hal Laboratory by sending target plates and identification projects via transportation and the INFECTIO_MALDI software (Infopartner, Nancy, France), respectively. The occurrence of transmission problems (<2 %) and human errors (<1 %) suggested that the system was sufficiently robust to be implemented in a network. With a median time-to-identification of 5 h and 11 min (78 min, min-max: 154-547), MALDI-TOF MS networking always provided a faster identification result than conventional techniques, except when chromogenic culture media and oxidase tests were used (p < 0.0001). However, the limited clinical benefits of the chromogenic culture media do not support their extra cost. Our financial analysis also suggested that MALDI-TOF MS networking could lead to substantial annual cost savings. MALDI-TOF MS networking presents many advantages, and few conventional techniques (optochin and oxidase tests) are required to ensure the same quality in patient care from the distant laboratory. Nevertheless, such networking should not be considered unless there is a reorganisation of workflow, efficient communication between teams, qualified technologists and a reliable IT department and helpdesk to manage potential connectivity problems.

  14. Direct Identification of Bacteria in Positive Blood Culture Bottles by Matrix-Assisted Laser Desorption Ionisation Time-of-Flight Mass Spectrometry

    PubMed Central

    La Scola, Bernard; Raoult, Didier

    2009-01-01

    Background With long delays observed between sampling and availability of results, the usefulness of blood cultures in the context of emergency infectious diseases has recently been questioned. Among methods that allow quicker bacterial identification from growing colonies, matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry was demonstrated to accurately identify bacteria routinely isolated in a clinical biology laboratory. In order to speed up the identification process, in the present work we attempted bacterial identification directly from blood culture bottles detected positive by the automate. Methodology/Principal Findings We prospectively analysed routine MALDI-TOF identification of bacteria detected in blood culture by two different protocols involving successive centrifugations and then lysis by trifluoroacetic acid or formic acid. Of the 562 blood culture broths detected as positive by the automate and containing one bacterial species, 370 (66%) were correctly identified. Changing the protocol from trifluoroacetic acid to formic acid improved identification of Staphylococci, and overall correct identification increased from 59% to 76%. Lack of identification was observed mostly with viridans streptococci, and only one false positive was observed. In the 22 positive blood culture broths that contained two or more different species, only one of the species was identified in 18 samples, no species were identified in two samples and false species identifications were obtained in two cases. The positive predictive value of bacterial identification using this procedure was 99.2%. Conclusions/Significance MALDI-TOF MS is an efficient method for direct routine identification of bacterial isolates in blood culture, with the exception of polymicrobial samples and viridans streptococci. It may replace routine identification performed on colonies, provided improvement for the specificity of blood culture broths growing viridans

  15. Mass Conservation and Chemical Kinetics.

    ERIC Educational Resources Information Center

    Barbara, Thomas M.; Corio, P. L.

    1980-01-01

    Presents a method for obtaining all mass conservation conditions implied by a given mechanism in which the conditions are used to simplify integration of the rate equations and to derive stoichiometric relations. Discusses possibilities of faulty inference of kinetic information from a given stoichiometry. (CS)

  16. Rapid identification of Burkholderia mallei and Burkholderia pseudomallei by intact cell Matrix-assisted Laser Desorption/Ionisation mass spectrometric typing

    PubMed Central

    2012-01-01

    Background Burkholderia (B.) pseudomallei and B. mallei are genetically closely related species. B. pseudomallei causes melioidosis in humans and animals, whereas B. mallei is the causative agent of glanders in equines and rarely also in humans. Both agents have been classified by the CDC as priority category B biological agents. Rapid identification is crucial, because both agents are intrinsically resistant to many antibiotics. Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) has the potential of rapid and reliable identification of pathogens, but is limited by the availability of a database containing validated reference spectra. The aim of this study was to evaluate the use of MALDI-TOF MS for the rapid and reliable identification and differentiation of B. pseudomallei and B. mallei and to build up a reliable reference database for both organisms. Results A collection of ten B. pseudomallei and seventeen B. mallei strains was used to generate a library of reference spectra. Samples of both species could be identified by MALDI-TOF MS, if a dedicated subset of the reference spectra library was used. In comparison with samples representing B. mallei, higher genetic diversity among B. pseudomallei was reflected in the higher average Eucledian distances between the mass spectra and a broader range of identification score values obtained with commercial software for the identification of microorganisms. The type strain of B. pseudomallei (ATCC 23343) was isolated decades ago and is outstanding in the spectrum-based dendrograms probably due to massive methylations as indicated by two intensive series of mass increments of 14 Da specifically and reproducibly found in the spectra of this strain. Conclusions Handling of pathogens under BSL 3 conditions is dangerous and cumbersome but can be minimized by inactivation of bacteria with ethanol, subsequent protein extraction under BSL 1 conditions and MALDI-TOF MS analysis being faster than

  17. European Code against Cancer 4th Edition: Ionising and non-ionising radiation and cancer.

    PubMed

    McColl, Neil; Auvinen, Anssi; Kesminiene, Ausrele; Espina, Carolina; Erdmann, Friederike; de Vries, Esther; Greinert, Rüdiger; Harrison, John; Schüz, Joachim

    2015-12-01

    Ionising radiation can transfer sufficient energy to ionise molecules, and this can lead to chemical changes, including DNA damage in cells. Key evidence for the carcinogenicity of ionising radiation comes from: follow-up studies of the survivors of the atomic bombings in Japan; other epidemiological studies of groups that have been exposed to radiation from medical, occupational or environmental sources; experimental animal studies; and studies of cellular responses to radiation. Considering exposure to environmental ionising radiation, inhalation of naturally occurring radon is the major source of radiation in the population - in doses orders of magnitude higher than those from nuclear power production or nuclear fallout. Indoor exposure to radon and its decay products is an important cause of lung cancer; radon may cause approximately one in ten lung cancers in Europe. Exposures to radon in buildings can be reduced via a three-step process of identifying those with potentially elevated radon levels, measuring radon levels, and reducing exposure by installation of remediation systems. In the 4th Edition of the European Code against Cancer it is therefore recommended to: "Find out if you are exposed to radiation from naturally high radon levels in your home. Take action to reduce high radon levels". Non-ionising types of radiation (those with insufficient energy to ionise molecules) - including extremely low-frequency electric and magnetic fields as well as radiofrequency electromagnetic fields - are not an established cause of cancer and are therefore not addressed in the recommendations to reduce cancer risk.

  18. The ionisation energy of cyclopentadienone: a photoelectron-photoion coincidence study

    NASA Astrophysics Data System (ADS)

    Ormond, Thomas K.; Hemberger, Patrick; Troy, Tyler P.; Ahmed, Musahid; Stanton, John F.; Ellison, G. Barney

    2015-08-01

    Imaging photoelectron photoion coincidence (iPEPICO) spectra of cyclopentadienone (C5H4=O and C5D4=O) have been measured at the Swiss Light Source Synchrotron (Paul Scherrer Institute, Villigen, Switzerland) at the Vacuum Ultraviolet (VUV) Beamline. Complementary to the photoelectron spectra, photoionisation efficiency curves were measured with tunable VUV radiation at the Chemical Dynamics Beamline at the Advanced Light Source Synchrotron (Lawrence Berkeley National Laboratory, Berkeley, CA, USA). For both experiments, molecular beams diluted in argon and helium were generated from the vacuum flash pyrolysis of o-phenylene sulphite in a resistively heated microtubular SiC flow reactor. The Franck-Condon profiles and ionisation energies were calculated at the CCSD(T) level of theory, and are in excellent agreement with the observed iPEPICO spectra. The ionisation energies of both cyclopentadienone-d0, IE(C5H4=O), and cyclopentadienone-d4, IE(C5D4=O), were observed to be the same: 9.41 ± 0.01 eV. The mass-selected threshold photoelectron spectrum (ms-TPES) of cyclopentadienone reveals that the C=C stretch in the ground state of the cation is excited upon ionisation, supporting computational evidence that the ground state of the cation is ? 2A2, and is in agreement with previous studies. However, the previously reported ionisation potential has been improved considerably in this work. In addition, since o-benzoquinone (o-O=C6H4=O and o-O=C6D4=O) is also produced in this process, its ms-TPES has been recorded. From the iPEPICO and photoionisation efficiency spectra, we infer an adiabatic ionisation energy of IE(o-O=C6H4=O) = 9.3 ± 0.1 eV, but the rather structureless spectrum indicates a strong change in geometry upon ionisation making this value less reliable.

  19. Biologic and chemical weapons of mass destruction.

    PubMed

    Bozeman, William P; Dilbero, Deanna; Schauben, Jay L

    2002-11-01

    Weapons of mass destruction (WMDs) are capable of producing massive casualties and are typically grouped into nuclear, biologic, and chemical weapons. In the wake of the September 11th disasters, attention to terrorist groups and the potential for use of WMDs has increased. Biologic and chemical weapons are relatively accessible and inexpensive to develop, and are thought to be the most available to foreign states and subnational terrorist groups. This article reviews various biologic and chemical weapons, including emergency diagnosis and management of selected agents.

  20. Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing.

    PubMed

    Adam, T W; Clairotte, M; Streibel, T; Elsasser, M; Pommeres, A; Manfredi, U; Carriero, M; Martini, G; Sklorz, M; Krasenbrink, A; Astorga, C; Zimmermann, R

    2012-07-01

    Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.

  1. Laser-based mass spectrometry for in situ chemical composition analysis of planetary surfaces

    NASA Astrophysics Data System (ADS)

    Frey, Samira; Neuland, Maike B.; Grimaudo, Valentine; Moreno-García, Pavel; Riedo, Andreas; Tulej, Marek; Broekmann, Peter; Wurz, Peter

    2016-04-01

    Mass spectrometry is an important analytical technique in space research. The chemical composition of planetary surface material is a key scientific question on every space mission to a planet, moon or asteroid. Chemical composition measurements of rocky material on the surface are of great importance to understand the origin and evolution of the planetary body.[1] A miniature laser ablation/ionisation reflectron- type time-of-flight mass spectrometer (instrument name LMS) was designed and built at the University of Bern for planetary research.[2] Despite its small size and light weight, the LMS instrument still maintains the same capabilities as large laboratory systems, which makes it suitable for its application on planetary space missions.[3-5] The high dynamic range of about eight orders of magnitude, high lateral (μm-level) and vertical (sub-nm level) resolution and high detection sensitivity for almost all elements (10 ppb, atomic fraction) make LMS a versatile instrument for various applications. LMS is a suitable instrument for in situ measurements of elemental and isotope composition with high precision and accuracy. Measurements of Pb- isotope abundances can be used for dating of planetary material. Measurements of bio-relevant elements allow searching for past or present life on a planetary surface. The high spatial resolution, both in lateral and vertical direction, is of considerable interest, e.g. for analysis of inhomogeneous, extraterrestrial samples as well as weathering processes of planetary material. References [1] P. Wurz, D. Abplanalp, M. Tulej, M. Iakovleva, V.A. Fernandes, A. Chumikov, and G. Managadze, "Mass Spectrometric Analysis in Planetary Science: Investigation of the Surface and the Atmosphere", Sol. Sys. Res., 2012, 46, 408. [2] U. Rohner, J.A. Whitby, P. Wurz, "A miniature laser ablation time of flight mass spectrometer for in situ planetary exploration" Meas. Sci. Tch., 2003, 14, 2159. [3] M. Tulej, A. Riedo, M.B. Neuland, S

  2. Fast nucleotide identification through fingerprinting using gold nanoparticle-based surface-assisted laser desorption/ionisation.

    PubMed

    Larguinho, Miguel; Capelo, José L; Baptista, Pedro V

    2013-02-15

    We report a method centred on gold nanoparticle-based surface-assisted laser desorption/ionisation for analysis of deoxynucleotides and alkylated nucleobases. Gold nanoparticles allow for enhanced analysis capability by eliminating undesired signature peaks; thus more elegant mass spectra can be attained that allow identification by nucleotide mass fingerprint. The resulting fingerprinting patterns on the spectra are compared and associated with the presence of different nucleotides in the sample. This method can be easily extended to modified nucleotides implicated in genome lesions due to exposure to environment chemicals, such as DNA adducts (e.g. guanine adducts). The use of gold nanoparticles for surface-assisted laser desorption/ionisation can be an useful tool to resolve common issues of background noise when analysing nucleic acids samples.

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

    SciTech Connect

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

    2012-06-29

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

  4. Cosmic-ray ionisation of dense molecular clouds

    NASA Astrophysics Data System (ADS)

    Vaupre, Solenn

    2015-07-01

    Cosmic rays (CR) are of tremendous importance in the dynamical and chemical evolution of interstellar molecular clouds, where stars and planets form. CRs are likely accelerated in the shells of supernova remnants (SNR), thus molecular clouds nearby can be irradiated by intense fluxes of CRs. CR protons have two major effects on dense molecular clouds: 1) when they encounter the dense medium, high-energy protons (>280 MeV) create pions that decay into gamma-rays. This process makes SNR-molecular cloud associations intense GeV and/or TeV sources whose spectra mimic the CR spectrum. 2) at lower energies, CRs penetrate the cloud and ionise the gas, leading to the formation of molecular species characteristic of the presence of CRs, called tracers of the ionisation. Studying these tracers gives information on low-energy CRs that are unaccessible to any other observations. I studied the CR ionisation of molecular clouds next to three SNRs: W28, W51C and W44. These SNRs are known to be interacting with the nearby clouds, from the presence of shocked gas, OH masers and pion-decay induced gamma-ray emission. My work includes millimeter observations and chemical modeling of tracers of the ionisation in these dense molecular clouds. In these three regions, we determined an enhanced CR ionisation rate, supporting the hypothesis of an origin of the CRs in the SNR nearby. The evolution of the CR ionisation rate with the distance to the SNR brings valuable constraints on the propagation properties of low-energy CRs. The method used relies on observations of the molecular ions HCO+ and DCO+, which shows crucial limitations at high ionisation. Therefore, I investigated, both through modeling and observations, the chemical abundances of several other species to try and identity alternative tracers of the ionisation. In particular, in the W44 region, observations of N2H+ bring additional constraints on the physical conditions, volatile abundances in the cloud, and the ionisation

  5. Classification of protein binders in artist's paints by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry: an evaluation of principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA).

    PubMed

    Fremout, Wim; Kuckova, Stepanka; Crhova, Michaela; Sanyova, Jana; Saverwyns, Steven; Hynek, Radovan; Kodicek, Milan; Vandenabeele, Peter; Moens, Luc

    2011-06-15

    Proteomics techniques are increasingly applied for the identification of protein binders in historical paints. The complex nature of paint samples, with different kinds of pigments mixed into, and degradation by long term exposure to light, humidity and temperature variations, requires solid analysis and interpretation methods. In this study matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectra of tryptic-digested paint replicas are subjected to principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) in order to distinguish proteinaceous binders based on animal glues, egg white, egg yolk and milk casein from each other. The most meaningful peptide peaks for a given protein class will be determined, and if possible, annotated with their corresponding amino acid sequence. The methodology was subsequently applied on egg temperas, as well as on animal glues from different species. In the latter small differences in the MALDI-TOF mass spectra can allow the determination of a mammal or sturgeon origin of the glue. Finally, paint samples from the 16(th) century altarpiece of St Margaret of Antioch (Mlynica, Slovakia) were analysed. Several expected peaks are either present in lower abundance or completely missing in these natural aged paints, due to degradation of the paints. In spite of this mammalian glue was identified in the St Margaret samples.

  6. Dissociation of biomolecules using a ultraviolet matrix-assisted laser desorption/ionisation time-of-flight/curved field reflectron tandem mass spectrometer equipped with a differential-pumped collision cell.

    PubMed

    Belgacem, Omar; Bowdler, Andrew; Brookhouse, Ian; Brancia, Francesco L; Raptakis, Emmanuel

    2006-01-01

    A commercial matrix-assisted laser desorption/ionisation time-of-flight (MALDI-ToF) instrument equipped with a curved field reflectron (CFR) was modified in order to perform collision-induced dissociation (CID) on a variety of biomolecules. The incorporation of a high-resolution ion gate together with a collision cell within the field-free region allowed tandem mass analysis (MS/MS), without the necessity to decelerate the precursor ions prior to activation. The simultaneous detection of all product ions remained possible by using the CFR. To test the MS/MS performances, ACTH (fragment 1-17), a complex high mannose carbohydrate (Man)(8)(GlcNac)(2) and a lysophosphatidylcholine lipid (18:1) were analysed on the modified instrument. Direct comparison with the low-energy product ion spectra, acquired on a MALDI quadrupole ion trap (QIT) two-stage reflectron time-of flight (ReToF) mass spectrometer, showed significant differences in the types of product ions observed. The additional ions detected were a clear indication of the high-energy fragmentation processes occurring in the collision cell.

  7. Identification of differentially expressed proteins of gamma-ray irradiated rat intestinal epithelial IEC-6 cells by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionisation-time of flight mass spectrometry.

    PubMed

    Bo, Zhang; Yongping, Su; Fengchao, Wang; Guoping, Ai; Yongjiang, Wei

    2005-02-01

    To identify proteins involved in the processes of cellular and molecular response to radiation damage repair in intestinal epithelial IEC-6 cells, we comparatively analyzed the proteome of irradiated IEC-6 cells with that of normal cells. A series of methods were used, including two-dimensional gel electrophoresis (Z-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and Swiss-Prot database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins. Image analysis revealed that averages of 608 +/- 39 and 595 +/- 31 protein spots were detected in normal and irradiated IEC-6 cells, respectively. Sixteen differential protein spots were isolated from gels, and measured with MALDI-TOF-MS. A total of 14 spots yielded good spectra, and 11 spots matched with known proteins after database searching. These proteins were mainly involved in anti-oxidation, metabolism, and protein post-translational processes. Western blotting confirmed that stress-70 protein was down-regulated by gamma-irradiation. Up-regulation of ERP29 was confirmed by RT-PCR, indicating that it is involved in ionizing radiation. The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of radiation damage repair in intestinal epithelial cells.

  8. High-performance liquid chromatography with electrospray ionisation mass spectrometry and diode array detection in the identification and quantification of the degradation products of calix[4]arene crown-6 under radiolysis.

    PubMed

    Lamouroux, C; Aychet, N; Lelièvre, A; Jankowski, C K; Moulin, C

    2004-01-01

    The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO(3) 3 M) and an extreme exposure to radiolysis (10(6) Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions.

  9. Characterisation by liquid chromatography coupled to electrospray ionisation ion trap mass spectrometry of phloroglucinol and 4-methylcatechol oxidation products to study the reactivity of epicatechin in an apple juice model system.

    PubMed

    Poupard, Pascal; Guyot, Sylvain; Bernillon, Stephane; Renard, Catherine M G C

    2008-02-01

    The reactivity of the (-)-epicatechin structure towards caffeoylquinic acid o-quinones was studied in an apple juice model solution. The approach consisted in considering separately the reactivities of the two phenolic moieties of an (-)-epicatechin molecule: phloroglucinol and 4-methylcatechol were chosen to represent A- and B-rings, respectively. The oxidation products were characterised by RP-HPLC coupled with electrospray ionisation Mass spectrometry (MS). The reactivities of the A- and B-rings were clearly different on the basis of the oxidation products formed. Both A- and B-rings could be involved in covalent bond formation, but electron transfers only occurred with the B-ring. Most of the (-)-epicatechin oxidation products were linked by A/B-ring linkage ("head-to-tail" intermolecular coupling). After this first dimerisation step, intramolecular reactions seemed to be favoured. Therefore, the complexity of oxidation products in apple juice does not only result from an extensive polymerisation of native phenolic compounds, but also from a multiplicity of small molecules in different oxidation states and isomeric forms.

  10. Hydrocarbon source apportionment in Mexico City using the chemical mass balance receptor model

    NASA Astrophysics Data System (ADS)

    Vega, Elizabeth; Mugica, Violeta; Carmona, Rocío.; Valencia, Edgar

    A field study was conducted in Mexico City during May-November 1997 to determine non-methane hydrocarbons (NMHC) species emitted from different sources: application of slow curing asphalt pavement, liquefied petroleum gas (vapour phase), dry cleaning, graphic arts, landfill, emissions of motor vehicle exhaust inside a tunnel, hot soak, whole gasoline, painting operations and degreasing. Forty-five ambient air samples of NMHC were simultaneously collected from 6:00 to 9:00 a.m. at three different sites, Xalostoc, Pedregal and La Merced, denominated receptors, during the spring and fall of 1996. In both cases samples were collected in stainless-steel canisters and analysed by gas chromatography with flame ionisation detection system. Based on these measurements the chemical mass receptor model (CMB) was applied to estimate the contribution of the different NMHC source to ambient pollution. The average results for the two sampling periods showed that the major sources of NMHC for the three sites were: motor vehicle exhaust with an average contribution of 54.9, 57.4 and 63.8% for Xalostoc, Pedregal and La Merced, respectively, followed by handling and distribution of liquefied petroleum gas with 28.5% in Xalostoc, 20.0% in Pedregal and 24.0% in La Merced.

  11. Species identification by analysis of bone collagen using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

    PubMed

    Buckley, Michael; Collins, Matthew; Thomas-Oates, Jane; Wilson, Julie C

    2009-12-01

    Species identification of fragmentary bone, such as in rendered meat and bone meal or from archaeological sites, is often difficult in the absence of clear morphological markers. Here we present a robust method of analysing genus-specific collagen peptides by mass spectrometry simply by using solid-phase extraction (a C18 ZipTip) for peptide purification, rather than liquid chromatography/mass spectrometry (LC/MS). Analysis of the collagen from 32 different mammal species identified a total of 92 peptide markers that could be used for species identification, for example, in processed food and animal feed. A set of ancient (>100 ka@10 degrees C) bone samples was also analysed to show that the proposed method has applications to archaeological bone identification.

  12. Detecting equilibrium cytochrome c folding intermediates by electrospray ionisation mass spectrometry: Two partially folded forms populate the molten-globule state

    PubMed Central

    Grandori, Rita

    2002-01-01

    Nanoelectrospray ionization mass spectrometry (nano-ESI-MS) is applied to the characterization of ferric cytochromec (cytc) conformational states under different solvent conditions. The methanol-induced molten-globule state in the pH range 2.6–3.0 is found to be populated by two distinct, partially folded conformers IA and IB. The more compact intermediate IB resembles that induced by glycerol in acid-unfolded cytc. The less compact one, IA, also can be induced by destabilization of the native structure by trifluoroethanol. IA and IB can be detected, in the absence of additives, around the midpoint of the acid-induced unfolding transition, providing direct evidence for involvement of equilibrium folding intermediates in cytc conformational transitions at low pH. This study shows that mass spectrometry can contribute to the characterization of molten-globule states of proteins by detection of distinct, although poorly populated, conformations involved in a dynamic equilibrium. PMID:11847268

  13. The analysis of dyes in ball point pen inks on single paper fibres using laser desorption ionisation time of flight mass spectrometry (LDI-TOFMS).

    PubMed

    Matthews, Broderick; Walker, G Stewart; Kobus, Hilton; Pigou, Paul; Bird, Carolyne; Smith, Glyn

    2011-06-15

    An important requisite for the forensic analysis of inks on documents is that damage to the document is avoided or minimised. This paper describes a technique for dye identification in ballpoint pen inks using LDI-TOFMS on single ink bearing paper fibres and its application to a case. A single ink bearing paper fibre can be prised from the surface of the document under a stereo microscope and presented to the instrument for analysis without further treatment. This sampling process causes imperceptible damage to the surface of the document. Clear mass spectrometric identification of the ink dyes is obtained. A case example is provided to illustrate the practical application of the technique.

  14. Validation of a method for the analysis of quinolones residues in bovine muscle by liquid chromatography with electrospray ionisation tandem mass spectrometry detection.

    PubMed

    Rubies, A; Vaquerizo, R; Centrich, F; Compañó, R; Granados, M; Prat, M D

    2007-04-15

    A liquid chromatography-tandem mass spectrometry method for the determination and confirmation of nine quinolones was optimised and validated according to Commission Decision 2002/657/EC. Analytes were extracted from veal muscle with water and extracts purified with 96-well plates Oasis HLB cartridges. Separation was carried out in a silica-based C(18) column (50mmx2.1mm) with mobile phases consisting of water/acetonitrile mixtures containing acetic acid. Linear calibration curves in the ranges 4-400 and 50-800ngg(-1), with correlation coefficients at least 0.995, were obtained for all the analytes. At concentration levels above 10ngg(-1), quantification errors were lower than 10% and repeatability and within-laboratory reproducibility standard deviations below 6% and 10%, respectively. Decision limits and detection capabilities are reported.

  15. Characterisation of isoform-specific tryptic peptides of rat cardiac myosin heavy chains using automated liquid chromatography-matrix assisted laser desorption ionisation (LC-MALDI) mass spectrometry.

    PubMed

    Burniston, Jatin G; Connolly, Joanne B

    2010-04-30

    Proteomics investigations using 2-dimensional electrophoresis (2-DE) cannot resolve the entire cardiac proteome because some proteins, including myosin heavy chains (MyHC), are insoluble in the buffers required for isoelectric focusing. Here, we report an automated mass spectrometry (MS) method complementary to 2-DE and capable of yielding important additional information. Rat myocardium was homogenised in standard lysis solution and centrifuged to produce a supernatant fraction, suitable for 2-DE. The pelleted fraction, which is normally discarded, was used for the current analysis. Proteins were digested with trypsin and the peptides fractionated by HPLC. Automated spotting of eluent fractions onto 384-well target plates and matrix-assisted laser desorption tandem time of flight (MALDI-ToF/ToF) MS were directed by dedicated software. Peptide ions were fragmented by collision-induced dissociation and the MS/MS spectra searched against the NCBI database using Mascot. This approach confidently identified 13 tryptic peptides specific to cardiac alpha-MyHC and 4 specific to beta-MyHC, which can be used to differentiate these highly homologous protein isoforms in future quantitative MS analyses.

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

    PubMed

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

    2004-10-01

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

  17. Quantitative analysis of phenolic compounds in Chinese hawthorn (Crataegus spp.) fruits by high performance liquid chromatography-electrospray ionisation mass spectrometry.

    PubMed

    Liu, Pengzhan; Kallio, Heikki; Lü, Deguo; Zhou, Chuansheng; Yang, Baoru

    2011-08-01

    Eleven major phenolic compounds (hyperoside, isoquercitrin, chlorogenic acid, ideain, epicatechin, two procyanidin (PA) dimers, three PA trimers and a PA dimer-hexoside) were quantified in the fruits of 22 cultivars/origins of three species of the Chinese hawthorn (Crataegus spp.) by HPLC-ESI-MS-SIR. Hyperoside (0.1-0.8mg/g dry mass [DM]), isoquercitrin (0.1-0.3mg/g DM), chlorogenic acid (0.2-1.6mg/g DM), epicatechin (0.9-11.7mg/g DM), PA B2 (0.7-12.4mg/g DM), PA dimer II (0.1-1.5mg/g DM), PA trimer I (0.1-2.7mg/g DM), PA trimer II (0.7-6.9mg/g DM), PA trimer III (0.01-1.2mg/g DM) and a PA dimer-hexoside (trace-1.1mg/g DM) were detected in all the samples. Ideain (0.0-0.7mg/g DM) was found in all the samples except Crataegus scabrifolia. Significant correlations between the contents of individual PA aglycons were observed (r>0.9, P<0.01). A strong correlation between flavonols was also shown (r=0.71, P<0.01). Fruits of Crataegus pinnatifida var. major had higher contents of PAs but lower contents of flavonols compared with Crataegus brettschneideri. The fruits of C. scabrifolia contained the highest level of PA dimer-hexoside, which was present in trace amounts in the fruits of C. pinnatifida.

  18. Ionisers in the management of bronchial asthma.

    PubMed Central

    Nogrady, S G; Furnass, S B

    1983-01-01

    Because of recent interest in the possible benefits to asthmatic patients of negative ion generators and the largely uncontrolled and inconclusive nature of earlier studies a double blind crossover study of this treatment was carried out in 20 subjects with stable asthma over six months. After an initial two week period without an ioniser, active or placebo ionisers were installed in subjects' bedrooms for two eight week periods separated by a four week "washout" period when no ioniser was present. The study was completed by a final four week period when no ioniser was present. Subjects were randomly allocated to receive an active or a placebo ioniser first. Subjects recorded their peak expiratory flow rate (PEFR) twice daily, completed a daily symptom score questionnaire, and noted any treatment they took on a diary card. Recordings were completed throughout the trial. Ion counts and dust concentrations were measured in subjects' bedrooms during the study. Mean ion counts rose considerably when ionisers were activated (p less than 0.001). There were no significant differences in PEFR, symptom score, or consumption of medication between the periods that active ionisers and either no ionisers or placebo ionisers were in operation. This study has failed to show a statistically significant benefit in asthmatic subjects from the use of negative ion generators. PMID:6364442

  19. Ionised outflows in z ~ 2.4 quasar host galaxies

    NASA Astrophysics Data System (ADS)

    Carniani, S.; Marconi, A.; Maiolino, R.; Balmaverde, B.; Brusa, M.; Cano-Díaz, M.; Cicone, C.; Comastri, A.; Cresci, G.; Fiore, F.; Feruglio, C.; La Franca, F.; Mainieri, V.; Mannucci, F.; Nagao, T.; Netzer, H.; Piconcelli, E.; Risaliti, G.; Schneider, R.; Shemmer, O.

    2015-08-01

    Aims: Outflows driven by active galactic nuclei (AGN) are invoked by galaxy evolutionary models to quench star formation and to explain the origin of the relations observed locally between super-massive black holes and their host galaxies. We here aim to detect extended ionised outflows in luminous quasars, where we expect the highest activity both in star formation and in black-hole accretion. Currently, there are only a few studies based on spatially resolved observations of outflows at high redshift, z > 2. Methods: We analysed a sample of six luminous (L > 1047 erg/s) quasars at z ~ 2.4, observed in H-band using the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematic analysis of the [Oiii] emission line at λ = 5007 Å. Results: We detect fast, spatially extended outflows in five out of six targets. [Oiii]λ5007 has a complex gas kinematic, with blue-shifted velocities of a few hundreds of km s-1 and line widths up to 1500 km s-1. Using the spectroastrometric method, we infer a size of the ionised outflows of up to ~2 kpc. The properties of the ionised outflows, mass outflow rate, momentum rate, and kinetic power, are correlated with the AGN luminosity. The increase in outflow rate with increasing AGN luminosity is consistent with the idea that a luminous AGN pushes away the surrounding gas through fast outflows that are driven by radiation pressure, which depends on the emitted luminosity. Conclusions: We derive mass outflow rates of about 6-700 M⊙ yr-1 for our sample, which are lower than those observed in molecular outflows. The physical properties of ionised outflows show dependences on AGN luminosity that are similar to those of molecular outflows, but indicate that the mass of ionised gas is lower than that of molecular outflows. Alternatively, this discrepancy between ionised and molecular outflows could be explained with different acceleration mechanisms. Based on Observations collected at the European Organisation for

  20. Mass conservative, positive definite integrator for atmospheric chemical dynamics

    NASA Astrophysics Data System (ADS)

    Nguyen, Khoi; Caboussat, Alexandre; Dabdub, Donald

    2009-12-01

    Air quality models compute the transformation of species in the atmosphere undergoing chemical and physical changes. The numerical algorithms used to predict these transformations should obey mass conservation and positive definiteness properties. Among all physical phenomena, the chemical kinetics solver provides the greatest challenge to attain these two properties. In general, most chemical kinetics solvers are mass conservative but not positive definite. In this article, a new numerical algorithm for the computation of chemical kinetics is presented. The integrator is called Split Single Reaction Integrator (SSRI). It is both mass conservative and positive definite. It solves each chemical reaction exactly and uses operator splitting techniques (symmetric split) to combine them into the entire system. The method can be used within a host integrator to fix the negative concentrations while preserving the mass, or it can be used as a standalone integrator that guarantees positive definiteness and mass conservation. Numerical results show that the new integrator, used as a standalone integrator, is second order accurate and stable under large fixed time steps when other conventional integrators are unstable.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  2. Selective laser ionisation of radionuclide 63Ni

    NASA Astrophysics Data System (ADS)

    Tsvetkov, G. O.; D’yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

    2017-02-01

    We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm‑1) → 3d 94d 2[7/2]4(49322.56 cm‑1) → AIS(67707.61 cm‑1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

  3. CHEMICAL MASS BALANCE MODEL: EPA-CMB8.2

    EPA Science Inventory

    The Chemical Mass Balance (CMB) method has been a popular approach for receptor modeling of ambient air pollutants for over two decades. For the past few years the U.S. Environmental Protection Agency's Office of Research and Development (ORD) and Office of Air Quality Plannin...

  4. Identification and Quantitative Measurements of Chemical Species by Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Zondlo, Mark A.; Bomse, David S.

    2005-01-01

    The development of a miniature gas chromatograph/mass spectrometer system for the measurement of chemical species of interest to combustion is described. The completed system is a fully-contained, automated instrument consisting of a sampling inlet, a small-scale gas chromatograph, a miniature, quadrupole mass spectrometer, vacuum pumps, and software. A pair of computer-driven valves controls the gas sampling and introduction to the chromatographic column. The column has a stainless steel exterior and a silica interior, and contains an adsorbent of that is used to separate organic species. The detection system is based on a quadrupole mass spectrometer consisting of a micropole array, electrometer, and a computer interface. The vacuum system has two miniature pumps to maintain the low pressure needed for the mass spectrometer. A laptop computer uses custom software to control the entire system and collect the data. In a laboratory demonstration, the system separated calibration mixtures containing 1000 ppm of alkanes and alkenes.

  5. Selective and trace determination of monochloramine in river water by chemical derivatization and liquid chromatography/tandem mass spectrometry analysis.

    PubMed

    Kinani, Said; Layousse, Stéphany; Richard, Bertille; Kinani, Aziz; Bouchonnet, Stéphane; Thoma, Astrid; Sacher, Frank

    2015-08-01

    Monochloramine (MCA) may enter the aquatic environment through three main sources: wastewater treatment plant effluents, industrial effluents and thermal power plant wastes. Up to date, there are no available data about the concentration levels of this chemical in river water due to lack of appropriate analytical methods. Therefore, sensitive and selective analytical methods for monochloramine analysis in river water are required to evaluate its environmental fate and its effects on aquatic ecosystems. Thus, in this study we describe a highly specific and sensitive method for monochloramine determination in river water. This method combines chemical derivatization of monochloramine into indophenol followed by liquid chromatography coupled to electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) analysis. Two precursor-to-product ion transitions were monitored (200→127 and 200→154) in positive ionisation mode, fulfilling the criteria of selectivity, in accordance with the European Legislation requirements (decision 2002/657/EC). Ion structures and fragmentation mechanisms have been proposed to explain the selected transitions. Linearity range, accuracy and precision of the method have been assessed according to the French method validation standard NF T90-210. Detecting the derivatized monochloramine (indophenol) in Multiple Reaction Monitoring (MRM) mode provided a limit of quantification of 40 ng L(-1) equivalent monochloramine. Applied to Loire river water (France), the developed method occasionally detected monochloramine at concentrations less than 300 ng L(-1), which could be explained by punctual discharges of water containing active chlorine upstream of the sampling point. Indeed, it is widely reported in the literature that the addition of chlorine to water containing ammonia (e.g., wastewater effluents and river water) may result in the instantaneous formation of monochloramine. The proposed method is a powerful tool that can be used in

  6. Electron impact ionisation of encapsulated 99mTc@C 60 and 99mTc@C 70

    NASA Astrophysics Data System (ADS)

    Đustebek, J. B.; Đorđević, V. R.; Cvetićanin, J. M.; Veličković, S. R.; Veljković, M. V.; Nešković, O. M.; Rakočević, Z. L.; Bibić, N. M.

    2010-03-01

    The present study shows simultaneous surface ionisation and electron impact ionisation during the formation and investigation of endohedral fullerenes 99mTc@C 60 and 99mTc@C 70. The endohedral fullerenes were generated using a mass spectrometer with a triple rhenium filament as an ion source. The ionisation energies (IE) determined were: 8.52 ± 0.25 eV for 99mTc@C 60 and 9.57 ± 0.25 eV for 99mTc@ C 70.

  7. OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-22

    The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

  8. Oxalate Mass Balance During Chemical Cleaning in Tank 5F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-08

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  9. Chemical characteristics of water masses in the Rockall Trough

    NASA Astrophysics Data System (ADS)

    McGrath, Triona; Nolan, Glenn; McGovern, Evin

    2012-03-01

    Direct observations of physical and chemical data in the Rockall Trough during February of 2008, 2009 and 2010 are presented. Results are compared to a similar WOCE transect, AR24, completed in November/December 1996. Temperature and salinity data have been used to identify the water masses present in the Trough, and have been combined with nutrient (nitrate, nitrite, phosphate, silicate) and oxygen data to produce a table outlining the chemical characteristics of each of the water masses. Eastern North Atlantic Water (ENAW) moving north through the Trough gains nutrients from a branch of the North Atlantic Current (NAC). Mediterranean Water (MW) was identified as a warm saline core, with characteristically low oxygen and low preformed nutrients along the Irish continental shelf break near 53°N. Found at a similar density level at the southern entrance to the Trough, Sub Arctic Intermediate Water (SAIW) has relatively high oxygen and preformed nutrients, likely entrained from the subpolar gyre when it was formed. LSW was identified as a prominent water mass between 1500 and 2000 m deep, with characteristically high oxygen content. Lower silicate, and to a lesser extent preformed nitrate, in 2009 coincide with a freshening of Labrador Sea Water (LSW) relative to other years, and could indicate a stronger influence from the Labrador Current when it was formed. Finally, traces of Antarctic Bottom Water (AABW) were found as far north as 53°N, indicated by a sharp increase in nutrient concentrations, particularly silicate in the deepest parts of the Trough.

  10. Chemical separations by bubble-assisted interphase mass-transfer.

    PubMed

    Boyd, David A; Adleman, James R; Goodwin, David G; Psaltis, Demetri

    2008-04-01

    We show that when a small amount of heat is added close to a liquid-vapor interface of a captive gas bubble in a microchannel, interphase mass-transfer through the bubble can occur in a controlled manner with only a slight change in the temperature of the fluid. We demonstrate that this method, which we refer to as bubble-assisted interphase mass-transfer (BAIM), can be applied to interphase chemical separations, e.g., simple distillation, without the need for high temperatures, vacuum, or active cooling. Although any source of localized heating could be used, we illustrate BAIM with an all-optical technique that makes use of the plasmon resonance in an array of nanoscale metal structures that are incorporated into the channel to produce localized heating of the fluid when illuminated by a stationary low-power laser.

  11. Tunnelling time in strong field ionisation

    NASA Astrophysics Data System (ADS)

    Landsman, Alexandra S.; Keller, Ursula

    2014-10-01

    We revisit the common approaches to tunnelling time in the context of attoclock experiments. These experiments measure tunnelling time using close-to-circularly polarised light of the infrared ultrashort laser pulse. We test the sensitivity of the attoclock measurements of tunnelling time to non-adiabatic effects, as described by a well-known theoretical model first developed by Perelomov, Popov, and Terent'ev. We find that in the case of ionisation of helium, both adiabatic and non-adiabatic theories give very similar predictions for ionisations times over a wide intensity range typical of ultrafast experiments.

  12. Constraining Anthropogenic and Biogenic Emissions Using Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Spencer, Kathleen M.

    Numerous gas-phase anthropogenic and biogenic compounds are emitted into the atmosphere. These gases undergo oxidation to form other gas-phase species and particulate matter. Whether directly or indirectly, primary pollutants, secondary gas-phase products, and particulate matter all pose health and environmental risks. In this work, ambient measurements conducted using chemical ionization mass spectrometry are used as a tool for investigating regional air quality. Ambient measurements of peroxynitric acid (HO2NO2) were conducted in Mexico City. A method of inferring the rate of ozone production, PO3, is developed based on observations of HO2NO 2, NO, and NO2. Comparison of this observationally based PO3 to a highly constrained photochemical box model indicates that regulations aimed at reducing ozone levels in Mexico City by reducing NOx concentrations may be effective at higher NO x levels than predicted using accepted photochemistry. Measurements of SO2 and particulate sulfate were conducted over the Los Angeles basin in 2008 and are compared to measurements made in 2002. A large decrease in SO2 concentration and a change in spatial distribution are observed. Nevertheless, only a modest reduction in sulfate concentration is observed at ground sites within the basin. Possible explanations for these trends are investigated. Two techniques, single and triple quadrupole chemical ionization mass spectrometry, were used to quantify ambient concentrations of biogenic oxidation products, hydroxyacetone and glycolaldehyde. The use of these techniques demonstrates the advantage of triple quadrupole mass spectrometry for separation of mass analogues, provided the collision-induced daughter ions are sufficiently distinct. Enhancement ratios of hydroxyacetone and glycolaldehyde in Californian biomass burning plumes are presented as are concentrations of these compounds at a rural ground site downwind of Sacramento.

  13. Solid-phase microextraction low temperature plasma mass spectrometry for the direct and rapid analysis of chemical warfare simulants in complex mixtures.

    PubMed

    Dumlao, Morphy C; Jeffress, Laura E; Gooding, J Justin; Donald, William A

    2016-06-21

    Solid-phase microextraction (SPME) is directly integrated with low temperature plasma ionisation mass spectrometry to rapidly detect organophosphate chemical warfare agent simulants and their hydrolysis products in chemical mixtures, including urine. In this sampling and ionization method, the fibre serves: (i) to extract molecules from their native environment, and (ii) as the ionization electrode that is used to desorb and ionize molecules directly from the SPME surface. By use of a custom fabricated SPME fibre consisting of a stainless steel needle coated with a Linde Type A (LTA) zeolitic microporous material and low temperature plasma mass spectrometry, protonated dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP) and pinacolyl methylphosphonic acid (PinMPA) can be detected at less than 100 ppb directly in water and urine. Organophosphates were not readily detected by this approach using an uncoated needle in negative control experiments. The use of the LTA coating significantly outperformed the use of a high alumina Zeolite Socony Mobil-5 (ZSM-5) coating of comparable thickness that is significantly less polar than LTA. By conditioning the LTA probe by immersion in an aqueous CuSO4 solution, the ion abundance for protonated DMMP increased by more than 300% compared to that obtained without any conditioning. Sample recovery values were between 96 and 100% for each analyte. The detection of chemical warfare agent analogues and hydrolysis products required less than 2 min per sample. A key advantage of this sampling and ionization method is that analyte ions can be directly and rapidly sampled from chemical mixtures, such as urine and seawater, without sample preparation or chromatography for sensitive detection by mass spectrometry. This ion source should prove beneficial for portable mass spectrometry applications because relatively low detection limits can be obtained without the use of compressed gases, fluid pumps, and lasers. Moreover, the

  14. The ram accelerator - A chemically driven mass launcher

    NASA Technical Reports Server (NTRS)

    Kaloupis, P.; Bruckner, A. P.

    1988-01-01

    The ram accelerator, a chemically propelled mass driver, is presented as a viable new approach for directly launching acceleration-insensitive payloads into low earth orbit. The propulsion principle is similar to that of a conventional air-breathing ramjet. The cargo vehicle resembles the center-body of a ramjet and travels through a tube filled with a pre-mixed fuel and oxidizer mixture. The launch tube acts as the outer cowling of the ramjet and the combustion process travels with the vehicle. Two drive modes of the ram accelerator propulsion system are described, which when used in sequence are capable of accelerating the vehicle to as high as 10 km/sec. The requirements are examined for placing a 2000 kg vehicle into a 500 km orbit with a minimum of on-board rocket propellant for circularization maneuvers. It is shown that aerodynamic heating during atmospheric transit results in very little ablation of the nose. An indirect orbital insertion scenario is selected, utilizing a three step maneuver consisting of two burns and aerobraking. An on-board propulsion system using storable liquid propellants is chosen in order to minimize propellant mass requirements, and the use of a parking orbit below the desired final orbit is suggested as a means to increase the flexibility of the mass launch concept. A vehicle design using composite materials is proposed that will best meet the structural requirements, and a preliminary launch tube design is presented.

  15. Ionisation en couche K et effet biologique

    NASA Astrophysics Data System (ADS)

    L'Hoir, A.; Herve Du Penhoat, M. A.; Champion, C.; Fayard, B.; Touati, A.; Abel, F.; Politis, M. F.; Despiney-Bailly, I.; Sabatier, L.; Chetioui, A.

    1998-04-01

    Initial steps of radiation action mechanism on biological targets are still undnown. The strong correlation observed between inactivation cross sections by heavy ions and K-vacancy production cross sections has drawn the attention on this process. Although quite minor in the energy deposition of these particles, the K-ionization process gives rise to quite efficient ionization clusters. Values of K-ionization biological effectivenesses extracted from measured relative biological efficiencies of ultra soft X-rays support the idea of a major -may be a dominant- contribution of the K-vacancy process to the biological effect of heavy ions. Les étapes initiales des mécanismes d'effet biologique des radiations sont encore mal connues. La forte corrélation observée entre sections efficaces d'inactivation par ions lourds et sections efficaces d'ionisation K a attiré l'attention sur ce processus. Bien que de faible probabilité, l'ionisation K engendre des grappes d'ionisation très efficaces. Les valeurs de rendement létal extraites des efficacités biologiques relatives mesurées pour les rayonnements X ultra-mous suggèrent une contribution majeure -peut-être dominante- de l'ionisation K à l'effet biologique des ions.

  16. [Determination of homocysteine by tandem mass spectrometry with chemical ionization].

    PubMed

    Miroshnichenko, I I; Platova, A I; Safarova, T P; Iakovleva, O B

    2014-01-01

    Homocysteine (Hcy) is an intermediate of methionine metabolism. High plasma Hcy concentrations are an independent risk factor for stroke, peripheral vascular disease, deep venous thrombosis, coronary disease, and cognitive deficiency. Apparently, it is a great importance to measure Hcy levels in human blood. A new method for the quantification of Hcy by means of reversed-phase LC/atmospheric pressure chemical ionization mass spectrometry has been developed. The MRM ion transition, m/z 136.0 ® 90.0 was used for Hcy quantification. The limit of detection was 0.4 mM, quantification was performed from 1 mM to 40 mM with coefficient of determination of R2=0,997. The method was applied successfully to Hcy determination in human blood.

  17. Mass Casualty Chemical Incident Operational Framework, Assessment and Best Practices

    SciTech Connect

    Greenwalt, R. J.; Hibbard, W. J.

    2016-05-04

    Emergency response agencies in most US communities are organized, sized, and equipped to manage those emergencies normally expected. Hospitals in particular do not typically have significant excess capacity to handle massive numbers of casualties, as hospital space is an expensive luxury if not needed. Unfortunately this means that in the event of a mass casualty chemical incident the emergency response system will be overwhelmed. This document provides a self-assessment means for emergency managers to examine their response system and identify shortfalls. It also includes lessons from a detailed analysis of five communities: Baltimore, Boise, Houston, Nassau County, and New Orleans. These lessons provide a list of potential critical decisions to allow for pre-planning and a library of best practices that may be helpful in reducing casualties in the event of an incident.

  18. Mass Casualty Chemical Incident Operational Framework, Assessment and Best Practices

    SciTech Connect

    Greenwalt, R.; Hibbard, W.

    2016-08-09

    Emergency response agencies in most US communities are organized, sized, and equipped to manage those emergencies normally expected. Hospitals in particular do not typically have significant excess capacity to handle massive numbers of casualties, as hospital space is an expensive luxury if not needed. Unfortunately this means that in the event of a mass casualty chemical incident the emergency response system will be overwhelmed. This document provides a self-assessment means for emergency managers to examine their response system and identify shortfalls. It also includes lessons from a detailed analysis of five communities: Baltimore, Boise, Houston, Nassau County, and New Orleans. These lessons provide a list of potential critical decisions to allow for pre-planning and a library of best practices that may be helpful in reducing casualties in the event of an incident.

  19. Mass transport measurements and modeling for chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Chiang, D.Y.; Fiadzo, O.G.; Hablutzel, N.

    1997-12-01

    This project involves experimental and modeling investigation of densification behavior and mass transport in fiber preforms and partially densified composites, and application of these results to chemical vapor infiltration (CVI) process modeling. This supports work on-going at ORNL in process development for fabrication of ceramic matrix composite (CMC) tubes. Tube-shaped composite preforms are fabricated at ORNL with Nextel{trademark} 312 fiber (3M Corporation, St. Paul, MN) by placing and compressing several layers of braided sleeve on a tubular mandrel. In terms of fiber architecture these preforms are significantly different than those made previously with Nicalon{trademark} fiber (Nippon Carbon Corp., Tokyo, Japan) square weave cloth. The authors have made microstructure and permeability measurements on several of these preforms and a few partially densified composites so as to better understand their densification behavior during CVI.

  20. Medical experimentation concerning chemical and biological weapons for mass destruction.

    PubMed

    Deutsch, Erwin

    2003-04-01

    This article is the text of a speech originally presented at the Second World Conference on Medical Ethics at Gijon, Spain, on 2 October 2002 under the title "Medical Experimentation Concerning Chemical and Biological Weapons for Mass Destruction: Clinical Design for New Smallpox Vaccines: Ethical and Legal Aspects." Experimentation on vaccines such as smallpox is subject to the usual ethical rules such as the need for informed consent. However, the participants will not often be at risk of catching the disease but expose themselves by taking part in the experimentation. Professor Deutsch explores the implications of this, including the position of vulnerable groups such as children, those with mental handicaps, and those acting under orders such as the miliary, the policy and fire officers.

  1. Tissue proteomics using chemical immobilization and mass spectrometry.

    PubMed

    Shah, Punit; Zhang, Bai; Choi, Caitlin; Yang, Shuang; Zhou, Jianying; Harlan, Robert; Tian, Yuan; Zhang, Zhen; Chan, Daniel W; Zhang, Hui

    2015-01-15

    Proteomics analysis is important for characterizing tissues to gain biological and pathological insights, which could lead to the identification of disease-associated proteins for disease diagnostics or targeted therapy. However, tissues are commonly embedded in optimal cutting temperature medium (OCT) or are formalin-fixed and paraffin-embedded (FFPE) in order to maintain tissue morphology for histology evaluation. Although several tissue proteomic analyses have been performed on FFPE tissues using advanced mass spectrometry (MS) technologies, high-throughput proteomic analysis of OCT-embedded tissues has been difficult due to the interference of OCT in the MS analysis. In addition, molecules other than proteins present in tissues further complicate tissue proteomic analysis. Here, we report the development of a method using chemical immobilization of proteins for peptide extraction (CIPPE). In this method, proteins are chemically immobilized onto a solid support; interferences from tissues and OCT embedding are removed by extensive washing of proteins conjugated on the solid support. Peptides are then released from the solid phase by proteolysis, enabling MS analysis. This method was first validated by eliminating OCT interference from a standard protein, human serum albumin, where all of the unique peaks contributed by OCT contamination were eradicated. Finally, this method was applied for the proteomic analysis of frozen and OCT-embedded tissues using iTRAQ (isobaric tag for relative and absolute quantitation) labeling and two-dimensional liquid chromatography tandem mass spectrometry. The data showed reproducible extraction and quantitation of 10,284 proteins from 3996 protein groups and a minimal impact of OCT embedding on the analysis of the global proteome of the stored tissue samples.

  2. Mass spectrometry-guided refinement of chemical energy buffers.

    PubMed

    Chen, T-R; Urban, P L

    2016-06-01

    Biocatalytic reactions often require supplying chemical energy and phosphate groups in the form of adenosine triphosphate (ATP). Auxiliary enzymes can be used to convert a reaction by-product-adenosine diphosphate (ADP)-back to ATP. By employing real-time mass spectrometry (RTMS), one can gain an insight into inter-conversions of reactants in multi-enzyme reaction systems and optimize the reaction conditions. In this study, temporal traces of ions corresponding to adenosine monophosphate (AMP), ADP and ATP provided vital information that could be used to adjust activities of the 'buffering enzymes'. Using the RTMS results as a feedback, we also characterized a bienzymatic energy buffer that enables the recovery of ATP in the cases where it is directly hydrolysed to AMP in the main enzymatic reaction. The significance of careful selection of enzyme activities-guided by RTMS-is exemplified in the synthesis of glucose-6-phosphate by hexokinase in the presence of a buffering enzyme, pyruvate kinase. Relative activities of the two enzymes, present in the reaction mixture, influence biosynthetic reaction yields. This observation supports the conclusion that optimization of chemical energy recycling procedures is critical for the biosynthetic reaction economy.

  3. Molecular secondary ion mass spectrometry: New dimensions in chemical characterization

    NASA Astrophysics Data System (ADS)

    Colton, Richard J.; Campana, Joseph E.; Kidwell, David A.; Ross, Mark M.; Wyatt, Jeffrey R.

    1985-04-01

    Secondary ion mass spectrometry (SIMS) has become a diverse tool for the study of many substances other than metals and semiconductors. This paper discusses the emission of polyatomic and molecular ions from surfaces that contain various inorganic and organic compounds including polymers and biomolecules. The mass and abundance distribution of cluster ions emitted from various solids — Van der Waals, metallic, ionic and covalent — are compared. Trends in the emission patterns are discussed in terms of a recombination or direct emission mechanism. The emission of molecular ions is also discussed with respect to the method of ionization and the various sample preparation and matrix-assisted procedures used. The matrices include various solid-state and liquid matrices such as ammonium chloride, charcoal, glycerol and gallium. Various chemical derivatization procedures have been developed to enhance the sensitivity of molecular SIMS and to detect selectively components in mixtures. The procedures are demonstrated for the low-level detection of airborne contaminants from paints, for the analysis of drugs in biological fluids, and for the sequencing of biomolecules such as peptides and sugars. The emission of characteristic fragment ions from the surfaces of polymers is also described for thick, insulating films.

  4. Estimating nutrient loadings using chemical mass balance approach.

    PubMed

    Jain, C K; Singhal, D C; Sharma, M K

    2007-11-01

    The river Hindon is one of the important tributaries of river Yamuna in western Uttar Pradesh (India) and carries pollution loads from various municipal and industrial units and surrounding agricultural areas. The main sources of pollution in the river include municipal wastes from Saharanpur, Muzaffarnagar and Ghaziabad urban areas and industrial effluents of sugar, pulp and paper, distilleries and other miscellaneous industries through tributaries as well as direct inputs. In this paper, chemical mass balance approach has been used to assess the contribution from non-point sources of pollution to the river. The river system has been divided into three stretches depending on the land use pattern. The contribution of point sources in the upper and lower stretches are 95 and 81% respectively of the total flow of the river while there is no point source input in the middle stretch. Mass balance calculations indicate that contribution of nitrate and phosphate from non-point sources amounts to 15.5 and 6.9% in the upper stretch and 13.1 and 16.6% in the lower stretch respectively. Observed differences in the load along the river may be attributed to uncharacterized sources of pollution due to agricultural activities, remobilization from or entrainment of contaminated bottom sediments, ground water contribution or a combination of these sources.

  5. MEMS device for mass market gas and chemical sensors

    NASA Astrophysics Data System (ADS)

    Kinkade, Brian R.; Daly, James T.; Johnson, Edward A.

    2000-08-01

    Gas and chemical sensors are used in many applications. Industrial health and safety monitors allow companies to meet OSHA requirements by detecting harmful levels of toxic or combustible gases. Vehicle emissions are tested during annual inspections. Blood alcohol breathalizers are used by law enforcement. Refrigerant leak detection ensures that the Earth's ozone layer is not being compromised. Industrial combustion emissions are also monitored to minimize pollution. Heating and ventilation systems watch for high levels of carbon dioxide (CO2) to trigger an increase in fresh air exchange. Carbon monoxide detectors are used in homes to prevent poisoning from poor combustion ventilation. Anesthesia gases are monitored during a patients operation. The current economic reality is that two groups of gas sensor technologies are competing in two distinct existing market segments - affordable (less reliable) chemical reaction sensors for consumer markets and reliable (expensive) infrared (IR) spectroscopic sensors for industrial, laboratory, and medical instrumentation markets. Presently high volume mass-market applications are limited to CO detectros and on-board automotive emissions sensors. Due to reliability problems with electrochemical sensor-based CO detectors there is a hesitancy to apply these sensors in other high volume applications. Applications such as: natural gas leak detection, non-invasive blood glucose monitoring, home indoor air quality, personal/portable air quality monitors, home fire/burnt cooking detector, and home food spoilage detectors need a sensor that is a small, efficient, accurate, sensitive, reliable, and inexpensive. Connecting an array of these next generation gas sensors to wireless networks that are starting to proliferate today creates many other applications. Asthmatics could preview the air quality of their destinations as they venture out into the day. HVAC systems could determine if fresh air intake was actually better than the air

  6. Partial ionisation cross-sections of 2-propanol and ethanal

    NASA Astrophysics Data System (ADS)

    Vacher, J. R.; Jorand, F.; Blin-Simiand, N.; Pasquiers, S.

    2006-04-01

    Electron impact ionisation of 2-propanol and ethanal is studied using mass spectrometry. Cross-sections of the formation of molecular ions and ionic fragments are measured between 14 and 86 eV. Free energy changes are evaluated using ab initio calculations. For 2-propanol, two ions, identified as CH 3CHOH + (45 amu) and CH3CHCH3+ (43 amu), contribute more than 75% to the total cross-section over the whole range of electron energies and are produced by simple bond cleavage in the molecular ion. Both processes occur spontaneously, leaving the molecular ion as a minority species. For ethanal, two ions, identified as HCO + (29 amu) and CH 3CO + (43 amu), and the molecular ion (44 amu) contribute more than 80% to the total cross-section. The ions of 29 and 43 amu result from a simple bond cleavage in the molecular ion. These sprocesses are not spontaneous and the contribution of the molecular ion becomes predominant at 15 eV and is therefore significant over the whole range of ionisation energies.

  7. The Multiplexed Chemical Kinetic Photoionization Mass Spectrometer: A New Approach To Isomer-resolved Chemical Kinetics

    SciTech Connect

    Osborne, David L.; Zou, Peng; Johnsen, Howard; Hayden, Carl C.; Taatjes, Craig A.; Knyazev, Vadim D.; North, Simon W.; Peterka, Darcy S.; Ahmed, Musahid; Leone, Stephen R.

    2008-08-28

    We have developed a multiplexed time- and photon-energy?resolved photoionizationmass spectrometer for the study of the kinetics and isomeric product branching of gasphase, neutral chemical reactions. The instrument utilizes a side-sampled flow tubereactor, continuously tunable synchrotron radiation for photoionization, a multi-massdouble-focusing mass spectrometer with 100percent duty cycle, and a time- and positionsensitive detector for single ion counting. This approach enables multiplexed, universal detection of molecules with high sensitivity and selectivity. In addition to measurement of rate coefficients as a function of temperature and pressure, different structural isomers can be distinguished based on their photoionization efficiency curves, providing a more detailed probe of reaction mechanisms. The multiplexed 3-dimensional data structure (intensity as a function of molecular mass, reaction time, and photoionization energy) provides insights that might not be available in serial acquisition, as well as additional constraints on data interpretation.

  8. Background ionising radiation: a pictorial perspective.

    PubMed

    Bibbo, Giovanni; Piotto, Lino

    2014-09-01

    Ionising radiation from natural sources, known as background radiation, has existed on earth since the earth's formation. The exposure of humans and other living creatures to this radiation is a feature of the earth's environment which is continuing and inescapable. The word "radiation" brings fear to many people: a fear of the unknown, as human's senses cannot detect the presence of ionising radiation. In this study, a catalogue of images of the distribution of radioactivity in every day objects and foods has been produced using an imaging plate from a computed radiography cassette. The aim of the study is that by visually demonstrating that every day objects and foods are radioactive would alleviate the fear of "radiation" by becoming aware that we live in a radioactive environment and even our body is radioactive.

  9. Large Scale Chemical Cross-linking Mass Spectrometry Perspectives

    PubMed Central

    Zybailov, Boris L.; Glazko, Galina V.; Jaiswal, Mihir; Raney, Kevin D.

    2014-01-01

    The spectacular heterogeneity of a complex protein mixture from biological samples becomes even more difficult to tackle when one’s attention is shifted towards different protein complex topologies, transient interactions, or localization of PPIs. Meticulous protein-by-protein affinity pull-downs and yeast-two-hybrid screens are the two approaches currently used to decipher proteome-wide interaction networks. Another method is to employ chemical cross-linking, which gives not only identities of interactors, but could also provide information on the sites of interactions and interaction interfaces. Despite significant advances in mass spectrometry instrumentation over the last decade, mapping Protein-Protein Interactions (PPIs) using chemical cross-linking remains time consuming and requires substantial expertise, even in the simplest of systems. While robust methodologies and software exist for the analysis of binary PPIs and also for the single protein structure refinement using cross-linking-derived constraints, undertaking a proteome-wide cross-linking study is highly complex. Difficulties include i) identifying cross-linkers of the right length and selectivity that could capture interactions of interest; ii) enrichment of the cross-linked species; iii) identification and validation of the cross-linked peptides and cross-linked sites. In this review we examine existing literature aimed at the large-scale protein cross-linking and discuss possible paths for improvement. We also discuss short-length cross-linkers of broad specificity such as formaldehyde and diazirine-based photo-cross-linkers. These cross-linkers could potentially capture many types of interactions, without strict requirement for a particular amino-acid to be present at a given protein-protein interface. How these shortlength, broad specificity cross-linkers be applied to proteome-wide studies? We will suggest specific advances in methodology, instrumentation and software that are needed to

  10. Electron impact ionisation cross sections of iron hydrogen clusters

    NASA Astrophysics Data System (ADS)

    Huber, Stefan E.; Sukuba, Ivan; Urban, Jan; Limtrakul, Jumras; Probst, Michael

    2016-09-01

    We computed electron impact ionisation cross sections (EICSs) of iron hydrogen clusters, FeH n with n = 1,2, ...,10, from the ionisation threshold to 10 keV using the Deutsch-Märk (DM) and the binary-encounter-Bethe (BEB) formalisms. The maxima of the cross sections for the iron hydrogen clusters range from 6.13 × 10-16 cm2 at 60 eV to 8.76 × 10-16 cm2 at 76 eV for BEB-AE (BEB method based on quantum-chemical data from all-electron basis sets) calculations, from 4.15 × 10-16 cm2 at 77 eV to 7.61 × 10-16 cm2 at 80 eV for BEB-ECP (BEB method based on quantum-chemical data from effective-core potentials for inner-core electrons) calculations and from 2.49 × 10-16 cm2 at 43.5 eV to 7.04 × 10-16 cm2 at 51 eV for the DM method. Cross sections calculated via the BEB method are substantially higher than the ones obtained via the DM method, up to a factor of about two for FeH and FeH2. The formation of Fe-H bonds depopulates the iron 4 s orbital, causing significantly lower cross sections for the small iron hydrides compared to atomic iron. Both the DM and BEB cross sections can be fitted perfectly against a simple expression used in modelling and simulation codes in the framework of nuclear fusion research. The energetics of the iron hydrogen clusters change substantially when exact exchange is present in the density functional, while the cluster geometries do not depend on this choice.

  11. Preliminary Investigation into Pyrotechnic Chemical Products via Mass Spectrometry Techniques

    DTIC Science & Technology

    2015-03-11

    predicted by theory. 15. SUBJECT TERMS mass spectrometry, gas chromatography , pyrolysis, combustion products, pyrotechnics 16. SECURITY CLASSIFICATION OF...Eric Miklaszewski Dr. Douglas Papenmeier Matthew Neiswinger Christina Yamamoto Approach: Pyrolysis / Gas Chromatography / Mass Spectrometry (Py/GC...Oven GC Column Sample Inlet 0 Mass Spectrometer Gas Chromatography GC Transfer Line Thermo Finnigan PolarisQ Ion Trap with Trace GC/MSn with a

  12. Comprehensive Mass Analysis for Chemical Processes, a Case Study on L-Dopa Manufacture

    EPA Science Inventory

    To evaluate the “greenness” of chemical processes in route selection and process development, we propose a comprehensive mass analysis to inform the stakeholders from different fields. This is carried out by characterizing the mass intensity for each contributing chemical or wast...

  13. Students' Conceptions of Ionisation Energy: A Cross-Cultural Study

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Taber, Keith S.; Liu, Xiufeng; Coll, Richard K.; Lorenzo, Mercedes; Li, Jia; Goh, Ngoh Khang; Chia, Lian Sai

    2008-01-01

    Previous studies have indicated that A-level students in the UK and Singapore have difficulty learning the topic of ionisation energy. A two-tier multiple-choice instrument developed in Singapore in an earlier study, the Ionisation Energy Diagnostic Instrument, was administered to A-level students in the UK, advanced placement high school students…

  14. Violation of the mass-action law in dilute chemical systems

    NASA Astrophysics Data System (ADS)

    Brogioli, Doriano

    2013-11-01

    The mass-action law, which predicts the rates of chemical reactions, is widely used for modeling the kinetics of the chemical reactions and their stationary states, also for complex chemical reaction networks. However, violations of the mass-action equations have been reported in various cases: in confined systems with a small number of molecules, in non-ideally-stirred systems, when the reactions are limited by the diffusion, at high concentrations of reactants, or in chemical reaction networks with marginally stable mass-action equations. In this paper, I describe a new mechanism, leading to the violation of the mass-action equations, that takes place at a low concentration of at least one of the reactants; in this limit, the reaction rates can be easily inferred from the chemical reaction network. I propose that this mechanism underlies the replication stability of the hypercycles, a class of chemical reaction networks hypothetically connected with abiogenesis. I provide two simple examples of chemical reaction networks in which the mechanism leading to the violation of the mass-action law is present. I study the two chemical reaction networks by means of a simulation performed with a cellular automaton model. The results have a general validity and represent a limitation of the validity of the mass-action law, which has been overlooked up to now in the studies about the chemical reaction networks.

  15. Toxic Industrial Chemicals: A Future Weapons of Mass Destruction Threat

    DTIC Science & Technology

    2007-11-02

    dependent on factors, such as temperature , pressure, and wind speed (US Army 1990; 1994; and 1998a). In addition to CW agents’ toxicities, their chemical...expected to be at especially high risk of shigellosis, malaria, sandfly fever, and cutaneous leishmaniasis (Quin 1992). Studies conducted since the war

  16. Simultaneous Determination of Celecoxib, Erlotinib, and its Metabolite Desmethyl-Erlotinib (OSI-420) in Rat Plasma by Liquid chromatography/Tandem Mass Spectrometry with Positive/Negative Ion-Switching Electrospray Ionisation.

    PubMed

    Thappali, Satheeshmanikandan R S; Varanasi, Kanthikiran; Veeraraghavan, Sridhar; Arla, Rambabu; Chennupati, Sandhya; Rajamanickam, Madheswaran; Vakkalanka, Swaroop; Khagga, Mukkanti

    2012-01-01

    A new method for the simultaneous determination of celecoxib, erlotinib, and its active metabolite desmethyl-erlotinib (OSI-420) in rat plasma, by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionization mode, was developed and validated. Protein precipitation with methanol was selected as the method for preparing the samples. The analytes were separated on a reverse-phase C(18) column (50mm×4.6mm i.d., 3μ) using methanol: 2 mM ammonium acetate buffer, and pH 4.0 as the mobile phase at a flow rate 0.8 mL/min. Sitagliptin and Efervirenz were used as the internal standards for quantification. The determination was carried out on a Theremo Finnigan Quantam ultra triple-quadrupole mass spectrometer, operated in selected reaction monitoring (SRM) mode using the following transitions monitored simultaneously: positive m/z 394.5→278.1 for erlotinib, m/z 380.3→278.1 for desmethyl erlotinib (OSI-420), and negative m/z -380.1→ -316.3 for celecoxib. The limits of quantification (LOQs) were 1.5 ng/mL for Celecoxib, erlotinib, and OSI-420. Within- and between-day accuracy and precision of the validated method were within the acceptable limits of < 15% at all concentrations. The quantitation method was successfully applied for the simultaneous estimation of celecoxib, erlotinib, and desmethyl erlotinib in a pharmacokinetic study in Wistar rats.

  17. UV/ozone cleaning of mass standards: results on the correlation between mass and surface chemical state

    NASA Astrophysics Data System (ADS)

    Fuchs, P.; Marti, K.; Grgić, G.; Russi, S.

    2014-10-01

    UV/ozone cleaning of 1 kg Au and steel mass artefacts was studied by direct mass comparison and surface chemical analysis by XPS. Both materials are oxidized with an increasing oxide layer thickness upon prolonged exposure time. The gain in mass is significant. The gold oxides are not stable and decompose with time in part at ambient. As shown for artefacts of stacked discs, cavities and interspaces were also cleaned, but with a much longer cleaning time. Stacked discs, having a completely different cleaning time, are questionable for the determination of sorption phenomena.

  18. Constraints on continental crustal mass loss via chemical weathering using lithium and its isotopes

    PubMed Central

    Liu, Xiao-Ming; Rudnick, Roberta L.

    2011-01-01

    Chemical weathering, as well as physical erosion, changes the composition and shapes the surface of the continental crust. However, the amount of continental material that has been lost over Earth’s history due to chemical weathering is poorly constrained. Using a mass balance model for lithium inputs and outputs from the continental crust, we find that the mass of continental crust that has been lost due to chemical weathering is at least 15% of the original mass of the juvenile continental crust, and may be as high as 60%, with a best estimate of approximately 45%. Our results suggest that chemical weathering and subsequent subduction of soluble elements have major impacts on both the mass and the compositional evolution of the continental crust. PMID:22184221

  19. New Polymer Coatings for Chemically Selective Mass Sensors

    NASA Technical Reports Server (NTRS)

    Sims, S. C.; Wright, Cassandra; Cobb, J.; McCalla, T.; Revelle, R.; Morris, V. R.; Pollack, S. K.

    1997-01-01

    There is a current need to develop sensitive and chemically specific sensors for the detection of nitric acid for in-situ measurements in the atmosphere. Polymer coatings have been synthesized and tested for their sensitivity and selectivity to nitric acid. A primary requirement for these polymers is detectability down to the parts per trillion range. The results of studies using these polymers as coatings for quartz crystal microbalances (QCM) and surface acoustic wave (SAW) devices will be presented.

  20. Ionisation Mechanisms in AN Optically Pumped Mercury Vapour.

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.

    Available from UMI in association with The British Library. Requires signed TDF. A plasma formed in a mercury vapour by optical pumping at visible and U.V. wavelengths from a high current mercury discharge, has been investigated with a view to gaining an understanding of the ionisation processes giving rise to the plasma. These were believed to generate both atomic and molecular ions. The results of this work have applications in the fields of fluorescent lighting and the mercury-nitrogen laser. The plasma was studied with a variety of diagnostic tools. Electron number densities and temperatures were determined using Langmuir probes operating in the orbital motion limited regime. Populations of the 6^3 P triplet states, believed to be the only significantly populated excited states in the plasma, were determined using absorption spectroscopy. Lastly, a quadrupole mass spectrometer, coupled to the plasma with an electrostatic ion transport system, was used to investigate the flux of atomic and molecular ions to a body at floating potential in the plasma. The Langmuir probe and absorption spectroscopy results were included into a model describing ion motions in the plasma, based around the ion fluid equations and including source terms for the generation of atomic and molecular ions, both by electron impact and by binary collisions of atoms in the 6^3P triplet states. Where possible, ionisation rats in the model were calculated using published cross-sections. However, for the heavy body collisional processes in particular, many of these are unknown. Consequently, an attempt was made to determine these cross-sections by generating results from the model that could be compared to experimental measurements of the atomic and molecular ion fluxes to the mass spectrometer. A number of computational experiments were carried out, varying the cross-sections until a good fit to the experimental measurements was achieved. Using this technique it was possible to estimate cross

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

    DTIC Science & Technology

    2005-10-01

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

  2. Multi-residue method for the determination of basic/neutral pharmaceuticals and illicit drugs in surface water by solid-phase extraction and ultra performance liquid chromatography-positive electrospray ionisation tandem mass spectrometry.

    PubMed

    Kasprzyk-Hordern, B; Dinsdale, R M; Guwy, A J

    2007-08-17

    The paper presents the development and validation of a new multi-residue method for the determination of 28 basic/neutral pharmaceuticals (antiepileptics, antibacterial drugs, beta-blockers, analgesics, lipid-regulating agents, bronchodilators, histamine-2-blockers, anti-inflammatory agents, calcium channel blockers, angiotensin-II antagonists and antidepressants) and illicit drugs in surface water with the usage of a new technique: ultra performance liquid chromatography-positive electrospray tandem mass spectrometry (UPLC-MS/MS). The usage of the novel UPLC system with 1.7 microm particle size and 1mm internal diameter column allowed for low mobile phase flow rates (0.07 mL min(-1)) and short retention times (from 1.3 to 15.5 min) for all compounds analysed. As a result, a fast and cost-effective method was developed. SPE with the usage of Oasis MCX strong cation-exchange mixed-mode polymeric sorbent was chosen for pharmaceuticals extraction from environmental samples. The influence of matrix-assisted ion suppression and low SPE recovery on the sensitivity of the method was studied. The instrumental limits of quantification varied from 0.2 to 10 microg L(-1). The method limits of quantification were at low nanogram per litre levels and ranged from 0.3 to 50 ng L(-1). The instrumental and method intra- and inter-day repeatabilities were on average less than 10%. The method was applied for the determination of pharmaceuticals in Rivers Taff (UK) and Warta (Poland). Fifteen compounds were determined in river water at levels ranging from single nanograms to single micrograms per litre.

  3. REVIEW OF VOLATILE ORGANIC COMPOUND SOURCE APPORTIONMENT BY CHEMICAL MASS BALANCE. (R826237)

    EPA Science Inventory

    The chemical mass balance (CMB) receptor model has apportioned volatile organic compounds (VOCs) in more than 20 urban areas, mostly in the United States. These applications differ in terms of the total fraction apportioned, the calculation method, the chemical compounds used ...

  4. Non Ionising Radiation as a Non Chemical Strategy in Regenerative Medicine: Ca2+-ICR “In Vitro” Effect on Neuronal Differentiation and Tumorigenicity Modulation in NT2 Cells

    PubMed Central

    Ledda, Mario; Megiorni, Francesca; Pozzi, Deleana; Giuliani, Livio; D’Emilia, Enrico; Piccirillo, Sara; Mattei, Cristiana; Grimaldi, Settimio; Lisi, Antonella

    2013-01-01

    In regenerative medicine finding a new method for cell differentiation without pharmacological treatment or gene modification and minimal cell manipulation is a challenging goal. In this work we reported a neuronal induced differentiation and consequent reduction of tumorigenicity in NT2 human pluripotent embryonal carcinoma cells exposed to an extremely low frequency electromagnetic field (ELF-EMF), matching the cyclotron frequency corresponding to the charge/mass ratio of calcium ion (Ca2+-ICR). These cells, capable of differentiating into post-mitotic neurons following treatment with Retinoic Acid (RA), were placed in a solenoid and exposed for 5 weeks to Ca2+-ICR. The solenoid was installed in a μ-metal shielded room to avoid the effect of the geomagnetic field and obtained totally controlled and reproducible conditions. Contrast microscopy analysis reveled, in the NT2 exposed cells, an important change in shape and morphology with the outgrowth of neuritic-like structures together with a lower proliferation rate and metabolic activity alike those found in the RA treated cells. A significant up-regulation of early and late neuronal differentiation markers and a significant down-regulation of the transforming growth factor-α (TGF-α) and the fibroblast growth factor-4 (FGF-4) were also observed in the exposed cells. The decreased protein expression of the transforming gene Cripto-1 and the reduced capability of the exposed NT2 cells to form colonies in soft agar supported these last results. In conclusion, our findings demonstrate that the Ca2+-ICR frequency is able to induce differentiation and reduction of tumorigenicity in NT2 exposed cells suggesting a new potential therapeutic use in regenerative medicine. PMID:23585910

  5. The mass balance approach: application to interpreting the chemical evolution of hydrologic systems.

    USGS Publications Warehouse

    Plummer, L.N.; Back, W.

    1980-01-01

    Mass balance calculations are applied to observed chemical and isotopic data of three natural water systems involving carbonate reactions in order to define mineral stoichiometry of reactants and products, relative rates of reactions, and mass transfer. One study evaluates reactions in a lagoon on the east coast of the Yucatan Peninsula, Mexico.- from Authors

  6. Upper limit to the mass of pulsationally stable stars with uniform chemical composition

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1992-01-01

    Nuclear-energized pulsational instability is a well-known feature of models of chemically homogeneous stars above a critical mass. With the Rogers-Iglesias opacities, the instability occurs above 120-150 solar mass for normal Galactic Population I chemical compositions, and above approximately 90 solar mass for stars in metal-poor environments like the outer Galaxy and the Small Magellanic Cloud. Models of homogeneous helium-burning stars are unstable above masses of 19 and 14 solar mass, respectively. These significant increases of the critical masses, in the normal metallicity cases, over the values derived previously with the Los Alamos opacities can explain the stability of the brightest observed O-type stars, but they do not exclude the possibility that the most luminous hydrogen-deficient Wolf-Rayet stars are experiencing this type of instability.

  7. Constraints on continental crustal mass loss via chemical weathering using lithium and its isotopes

    NASA Astrophysics Data System (ADS)

    Rudnick, R. L.; Liu, X. M.

    2012-04-01

    The continental crust has an "intermediate" bulk composition that is distinct from primary melts of peridotitic mantle (basalt or picrite). This mismatch between the "building blocks" and the "edifice" that is the continental crust points to the operation of processes that preferentially remove mafic to ultramafic material from the continents. Such processes include lower crustal recycling (via density foundering or lower crustal subduction - e.g., relamination, Hacker et al., 2011, EPSL), generation of evolved melts via slab melting, and/or chemical weathering. Stable isotope systems point to the influence of chemical weathering on the bulk crust composition: the oxygen isotope composition of the bulk crust is distinctly heavier than that of primary, mantle-derived melts (Simon and Lecuyer, 2005, G-cubed) and the Li isotopic composition of the bulk crust is distinctly lighter than that of mantle-derive melts (Teng et al., 2004, GCA; 2008, Chem. Geol.). Both signatures mark the imprint of chemical weathering on the bulk crust composition. Here, we use a simple mass balance model for lithium inputs and outputs from the continental crust to quantify the mass lost due to chemical weathering. We find that a minimum of 15%, a maximum of 60%, and a best estimate of ~40% of the original juvenile rock mass may have been lost via chemical weathering. The accumulated percentage of mass loss due to chemical weathering leads to an average global chemical weathering rate (CWR) of ~ 1×10^10 to 2×10^10 t/yr since 3.5 Ga, which is about an order of magnitude higher than the minimum estimates based on modern rivers (Gaillardet et al., 1999, Chem. Geol.). While we cannot constrain the exact portion of crustal mass loss via chemical weathering, given the uncertainties of the calculation, we can demonstrate that the weathering flux is non-zero. Therefore, chemical weathering must play a role in the evolution of the composition and mass of the continental crust.

  8. A miniaturised laser ablation/ionisation analyser for investigation of elemental/isotopic composition with the sub-ppm detection sensitivity

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

    2012-04-01

    Detailed knowledge of the elemental and isotopic composition of solar system objects imposes critical constraints on models describing the origin of our solar system and can provide insight to chemical and physical processes taking place during the planetary evolution. So far, the investigation of chemical composition of planetary surfaces could be conducted almost exclusively by remotely controlled spectroscopic instruments from orbiting spacecraft, landers or rovers. With some exceptions, the sensitivity of these techniques is, however, limited and often only abundant elements can be investigated. Nevertheless, the spectroscopic techniques proved to be successful for global chemical mapping of entire planetary objects such as the Moon, Mars and asteroids. A combined afford of the measurements from orbit, landers and rovers can also yield the determination of local mineralogy. New instruments including Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation/Ionisation Mass Spectrometer (LIMS), have been recently included for several landed missions. LIBS is thought to improve flexibility of the investigations and offers a well localised chemical probing from distances up to 10-13 m. Since LIMS is a mass spectrometric technique it allows for very sensitive measurements of elements and isotopes. We will demonstrate the results of the current performance tests obtained by application of a miniaturised laser ablation/ionisation mass spectrometer, a LIMS instrument, developed in Bern for the chemical analysis of solids. So far, the only LIMS instrument on a spacecraft is the LAZMA instrument. This spectrometer was a part of the payload for PHOBOS-GRUNT mission and is also currently selected for LUNA-RESURCE and LUNA-GLOB missions to the lunar south poles (Managadze et al., 2011). Our LIMS instrument has the dimensions of 120 x Ø60 mm and with a weight of about 1.5 kg (all electronics included), it is the lightest mass analyser designed for in situ chemical

  9. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  10. Applications of Mass Spectrometry in Investigations of Alleged Use of Chemical Warfare Agents

    NASA Astrophysics Data System (ADS)

    Read, Robert W.

    Chemical warfare agents were used extensively throughout the twentieth century. Many such uses are well documented; however some allegations of use of chemical warfare agents were not easily confirmed. During the early 1980s interest developed into investigation of alleged use by analytical techniques, particularly mass spectrometry. Since that time, many combined chromatographic - mass spectrometric methods have been developed, both for application to the analysis of environmental and biomedical samples and for investigation of physiological interactions of chemical warfare agents. Examples are given of some of the investigations in which the author has been involved, including those into Yellow Rain and uses of chemical warfare agents in Iraq and Iran. These examples illustrate the use of combined chromatographic-mass spectrometric methods and emphasise the importance of controls in analytical investigations.

  11. Rapid screening of anabolic steroids in horse urine with ultra-high-performance liquid chromatography/tandem mass spectrometry after chemical derivatisation.

    PubMed

    Wong, Colton H F; Leung, David K K; Tang, Francis P W; Wong, Jenny K Y; Yu, Nola H; Wan, Terence S M

    2012-04-06

    Liquid chromatography/mass spectrometry (LC/MS) has been successfully applied to the detection of anabolic steroids in biological samples. However, the sensitive detection of saturated hydroxysteroids, such as androstanediols, by electrospray ionisation (ESI) is difficult because of their poor ability to ionise. In view of this, chemical derivatisation has been used to enhance the detection sensitivity of hydroxysteroids by LC/MS. This paper describes the development of a sensitive ultra-high-performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) method for the screening of anabolic steroids in horse urine by incorporating a chemical derivatisation step, using picolinic acid as the derivatisation reagent. The method involved solid-phase extraction (SPE) of both free and conjugated anabolic steroids in horse urine using a polymer-based SPE cartridge (Abs Elut Nexus). The conjugated steroids in the eluate were hydrolysed by methanolysis and the resulting extract was further cleaned up by liquid-liquid extraction. The resulting free steroids in the extract were derivatised with picolinic acid to form the corresponding picolinoyl esters and analysed by UHPLC/MS/MS in the positive ESI mode with selected-reaction-monitoring. Separation of the targeted steroids was performed on a C18 UHPLC column. The instrument turnaround time was 10.5 min inclusive of post-run equilibration. A total of thirty-three anabolic steroids (including 17β-estradiol, 5(10)-estrene-3β,17α-diol, 5α-estrane-3β,17α-diol, 17α-ethyl-5α-estran-3α,17β-diol, 17α-methyl-5α-androstan-3,17β-diols, androstanediols, nandrolone and testosterone) spiked in negative horse urine at the QC levels (ranging from 0.75 to 30 ng/mL) could be consistently detected. The intra-day and inter-day precisions (% RSD) for the peak area ratios were around 7-51% and around 1-72%, respectively. The intra-day and inter-day precisions (% RSD) for the relative retention times were both less than 1% for

  12. Chemical ionization tandem mass spectrometer for the in situ measurement of methyl hydrogen peroxide

    SciTech Connect

    St Clair, Jason M.; McCabe, David C.; Crounse, John D.; Steiner, Urs; Wennberg, Paul O.

    2010-09-15

    A new approach for measuring gas-phase methyl hydrogen peroxide [(MHP) CH{sub 3}OOH] utilizing chemical ionization mass spectrometry is presented. Tandem mass spectrometry is used to avoid mass interferences that hindered previous attempts to measure atmospheric CH{sub 3}OOH with CF{sub 3}O{sup -} clustering chemistry. CH{sub 3}OOH has been successfully measured in situ using this technique during both airborne and ground-based campaigns. The accuracy and precision for the MHP measurement are a function of water vapor mixing ratio. Typical precision at 500 pptv MHP and 100 ppmv H{sub 2}O is {+-}80 pptv (2 sigma) for a 1 s integration period. The accuracy at 100 ppmv H{sub 2}O is estimated to be better than {+-}40%. Chemical ionization tandem mass spectrometry shows considerable promise for the determination of in situ atmospheric trace gas mixing ratios where isobaric compounds or mass interferences impede accurate measurements.

  13. Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry.

    PubMed

    Lin, Shu-Hsuan; Lo, Ta-Ju; Kuo, Fang-Yin; Chen, Yu-Chie

    2014-01-01

    Ultrasonication has been used to accelerate chemical reactions. It would be ideal if ultrasonication-assisted chemical reactions could be monitored by suitable detection tools such as mass spectrometry in real time. It would be helpful to clarify reaction intermediates/products and to have a better understanding of reaction mechanism. In this work, we developed a system for ultrasonication-assisted spray ionization mass spectrometry (UASI-MS) with an ~1.7 MHz ultrasonic transducer to monitor chemical reactions in real time. We demonstrated that simply depositing a sample solution on the MHz-based ultrasonic transducer, which was placed in front of the orifice of a mass spectrometer, the analyte signals can be readily detected by the mass spectrometer. Singly and multiply charged ions from small and large molecules, respectively, can be observed in the UASI mass spectra. Furthermore, the ultrasonic transducer used in the UASI setup accelerates the chemical reactions while being monitored via UASI-MS. The feasibility of using this approach for real-time acceleration/monitoring of chemical reactions was demonstrated. The reactions of Girard T reagent and hydroxylamine with steroids were used as the model reactions. Upon the deposition of reactant solutions on the ultrasonic transducer, the intermediate/product ions are readily generated and instantaneously monitored using MS within 1 s. Additionally, we also showed the possibility of using this reactive UASI-MS approach to assist the confirmation of trace steroids from complex urine samples by monitoring the generation of the product ions.

  14. Mass spectrometry in identification of ecotoxicants including chemical and biological warfare agents.

    PubMed

    Lebedev, Albert T

    2005-09-01

    Mass spectrometry is a unique tool to detect and identify trace levels of organic and bioorganic compounds as well as microorganisms in the environment. The range of potential chemical warfare (CW) and biological warfare (BW) agents is very broad. An important advantage of mass spectrometry over other techniques involves potential for full spectrum detection of chemical and biological agents including mid-spectrum materials (i.e. bioactive peptides, toxins, etc.) for which biological approaches are inadequate. Being very fast (seconds and minutes), extremely sensitive (zeptomoles 10(-21)), and informative (detailed qualitative and quantitative composition of mixtures containing hundreds of chemicals), mass spectrometry is a principal analytical tool at the sites of destruction of CW. Due to its unique features, mass spectrometry is applied not only for the detection of CW agents, but for the analysis of products of metabolism and degradation of these agents in organisms or environment as well. The present paper deals with some examples of successful application of mass spectrometry for the analyses of ecotoxicants, chemical warfare agents, explosives, and microorganisms including biology warfare agents.

  15. Mass spectrometry in identification of ecotoxicants including chemical and biological warfare agents

    SciTech Connect

    Lebedev, Albert T. . E-mail: lebedev@org.chem.msu.ru

    2005-09-01

    Mass spectrometry is a unique tool to detect and identify trace levels of organic and bioorganic compounds as well as microorganisms in the environment. The range of potential chemical warfare (CW) and biological warfare (BW) agents is very broad. An important advantage of mass spectrometry over other techniques involves potential for full spectrum detection of chemical and biological agents including mid-spectrum materials (i.e. bioactive peptides, toxins, etc.) for which biological approaches are inadequate. Being very fast (seconds and minutes), extremely sensitive (zeptomoles 10{sup -21}), and informative (detailed qualitative and quantitative composition of mixtures containing hundreds of chemicals), mass spectrometry is a principal analytical tool at the sites of destruction of CW. Due to its unique features, mass spectrometry is applied not only for the detection of CW agents, but for the analysis of products of metabolism and degradation of these agents in organisms or environment as well. The present paper deals with some examples of successful application of mass spectrometry for the analyses of ecotoxicants, chemical warfare agents, explosives, and microorganisms including biology warfare agents.

  16. Quantitative analysis of berberine in urine samples by chemical ionization mass fragmentography.

    PubMed

    Miyazaki, H; Shirai, E; Ishibashi, M; Niizima, K

    1978-05-11

    A highly specific and sensitive method has been developed for the quantitative determination of berberine in human urine. In order to carry out the microdetermination of berberine by chemical ionization mass fragmentography, berberine was reduced with sodium borohydride in methanol to tetrahydroberberine and subjected to gas chromatography-mass spectrometry. Berberine concentrations as low as 1 ng/ml urine can be measured by this method, with [2H3]berberine chloride as an internal standard.

  17. Meta-Analysis of Mass Balances Examining Chemical Fate during Wastewater Treatment

    PubMed Central

    2008-01-01

    Mass balances are an instructive means for investigating the fate of chemicals during wastewater treatment. In addition to the aqueous-phase removal efficiency (Φ), they can inform on chemical partitioning, transformation, and persistence, as well as on the chemical loading to streams and soils receiving, respectively, treated effluent and digested sewage sludge (biosolids). Release rates computed on a per-capita basis can serve to extrapolate findings to a larger scale. This review examines over a dozen mass balances conducted for various organic wastewater contaminants, including prescription drugs, estrogens, fragrances, antimicrobials, and surfactants of differing sorption potential (hydrophobicity), here expressed as the 1-octanol−water partition coefficient (KOW) and the organic carbon normalized sorption coefficient (KOC). Major challenges to mass balances are the collection of representative samples and accurate quantification of chemicals in sludge. A meta-analysis of peer-reviewed data identified sorption potential as the principal determinant governing chemical persistence in biosolids. Occurrence data for organic wastewater compounds detected in digested sludge followed a simple nonlinear model that required only KOW or KOC as the input and yielded a correlation coefficient of 0.9 in both instances. The model predicted persistence in biosolids for the majority (>50%) of the input load of organic wastewater compounds featuring a log10KOW value of greater than 5.2 (log10KOC > 4.4). In contrast, hydrophobicity had no or only limited value for estimating, respectively, Φ and the overall persistence of a chemical during conventional wastewater treatment. PMID:18800497

  18. Coupled sulfur isotopic and chemical mass transfer modeling: Approach and application to dynamic hydrothermal processes

    SciTech Connect

    Janecky, D.R.

    1988-09-21

    A computational modeling code (EQPSreverse arrowS) has been developed to examine sulfur isotopic distribution pathways coupled with calculations of chemical mass transfer pathways. A post processor approach to EQ6 calculations was chosen so that a variety of isotopic pathways could be examined for each reaction pathway. Two types of major bounding conditions were implemented: (1) equilibrium isotopic exchange between sulfate and sulfide species or exchange only accompanying chemical reduction and oxidation events, and (2) existence or lack of isotopic exchange between solution species and precipitated minerals, parallel to the open and closed chemical system formulations of chemical mass transfer modeling codes. All of the chemical data necessary to explicitly calculate isotopic distribution pathways is generated by most mass transfer modeling codes and can be input to the EQPS code. Routines are built in to directly handle EQ6 tabular files. Chemical reaction models of seafloor hydrothermal vent processes and accompanying sulfur isotopic distribution pathways illustrate the capabilities of coupling EQPSreverse arrowS with EQ6 calculations, including the extent of differences that can exist due to the isotopic bounding condition assumptions described above. 11 refs., 2 figs.

  19. Mass spectrometry of polycyclic tetracarboxylic ('ARN') acids and tetramethyl esters.

    PubMed

    Sutton, Paul A; Smith, Benjamin E; Rowland, Steven J

    2010-11-15

    Polycyclic C(80) tetracarboxylic (so-called 'ARN') acids are found as calcium salts in deposits which form in certain oilfield pipelines and equipment. Characterisation of these acids is important for improving the prediction and hence avoidance or minimisation of oilfield deposition problems. Although several of the acids have been isolated and characterised (as regioisomeric mixtures) by nuclear magnetic resonance spectroscopy, mass spectrometric methods are likely to be much more useful for the routine analysis of oils and deposits containing the acids. A publication summarising the mass spectra of the purified acids and major derivatives might thus be a very useful source of reference for scientists and technologists studying these unusual compounds. We now report the characterisation of several of the purified acids and of the tetramethyl esters by electrospray ionisation mass spectrometry (ESI-MS) in both positive ion and negative ion modes, by multistage ESI-MS with a suggested rationalisation of the ions produced, by positive ion atmospheric solids analysis probe (ASAP) atmospheric pressure chemical ionisation (APCI), and by positive ion electron ionisation (EI)-MS. Tentative identifications of C(80) acyclic, mono-, bi- and tricylic tetraacids and the δ(13)C isotope values of a mixture of the semi-pure acids determined by MS are also reported for the first time.

  20. Computer language for identifying chemicals with comprehensive two-dimensional gas chromatography and mass spectrometry.

    PubMed

    Reichenbach, Stephen E; Kottapalli, Visweswara; Ni, Mingtian; Visvanathan, Arvind

    2005-04-15

    This paper describes a language for expressing criteria for chemical identification with comprehensive two-dimensional gas chromatography paired with mass spectrometry (GC x GC-MS) and presents computer-based tools implementing the language. The Computer Language for Indentifying Chemicals (CLIC) allows expressions that describe rules (or constraints) for selecting chemical peaks or data points based on multi-dimensional chromatographic properties and mass spectral characteristics. CLIC offers chromatographic functions of retention times, functions of mass spectra, numbers for quantitative and relational evaluation, and logical and arithmetic operators. The language is demonstrated with the compound-class selection rules described by Welthagen et al. [W. Welthagen, J. Schnelle-Kreis, R. Zimmermann, J. Chromatogr. A 1019 (2003) 233-249]. A software implementation of CLIC provides a calculator-like graphical user-interface (GUI) for building and applying selection expressions. From the selection calculator, expressions can be used to select chromatographic peaks that meet the criteria or create selection chromatograms that mask data points inconsistent with the criteria. Selection expressions can be combined with graphical, geometric constraints in the retention-time plane as a powerful component for chemical identification with template matching or used to speed and improve mass spectrum library searches.

  1. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOEpatents

    Grindstaff, Quirinus G.

    1992-01-01

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  2. MICHTOX: A MASS BALANCE AND BIOACCUMULATION MODEL FOR TOXIC CHEMICALS IN LAKE MICHIGAN

    EPA Science Inventory

    MICHTOX is a toxic chemical mass balance and bioaccumulation model for Lake Michigan. It was developed for USEPA's Region V in support of the Lake Michigan Lake-wide Management Plan (LaMP) to provide guidance on expected water quality improvements in response to critical pollutan...

  3. Robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming.

    PubMed

    Baran, Richard; Northen, Trent R

    2013-10-15

    Untargeted metabolite profiling using liquid chromatography and mass spectrometry coupled via electrospray ionization is a powerful tool for the discovery of novel natural products, metabolic capabilities, and biomarkers. However, the elucidation of the identities of uncharacterized metabolites from spectral features remains challenging. A critical step in the metabolite identification workflow is the assignment of redundant spectral features (adducts, fragments, multimers) and calculation of the underlying chemical formula. Inspection of the data by experts using computational tools solving partial problems (e.g., chemical formula calculation for individual ions) can be performed to disambiguate alternative solutions and provide reliable results. However, manual curation is tedious and not readily scalable or standardized. Here we describe an automated procedure for the robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming optimization (RAMSI). Chemical rules among related ions are expressed as linear constraints and both the spectra interpretation and chemical formula calculation are performed in a single optimization step. This approach is unbiased in that it does not require predefined sets of neutral losses and positive and negative polarity spectra can be combined in a single optimization. The procedure was evaluated with 30 experimental mass spectra and was found to effectively identify the protonated or deprotonated molecule ([M + H](+) or [M - H](-)) while being robust to the presence of background ions. RAMSI provides a much-needed standardized tool for interpreting ions for subsequent identification in untargeted metabolomics workflows.

  4. Application of mass spectrometry in the characterization of chemicals in coal-derived liquids.

    PubMed

    Liu, Fang-Jing; Fan, Maohong; Wei, Xian-Yong; Zong, Zhi-Min

    2016-04-13

    Coal-derived liquids (CDLs) are primarily generated from pyrolysis, carbonization, gasification, direct liquefaction, low-temperature extraction, thermal dissolution, and mild oxidation. CDLs are important feedstocks for producing value-added chemicals and clean liquid fuels as well as high performance carbon materials. Accordingly, the compositional characterization of chemicals in CDLs at the molecular level with advanced analytical techniques is significant for the efficient utilization of CDLs. Although reviews on advancements have been rarely reported, great progress has been achieved in this area by using gas chromatography/mass spectrometry (GC/MS), two-dimensional GC-time of flight mass spectrometry (GC × GC-TOFMS), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This review focuses on characterizing hydrocarbon, oxygen-containing, nitrogen-containing, sulfur-containing, and halogen-containing chemicals in various CDLs with these three mass spectrometry techniques. Small molecular (< 500 u), volatile and semi-volatile, and less polar chemicals in CDLs have been identified with GC/MS and GC × GC-TOFMS. By equipped with two-dimensional GC, GC × GC-TOFMS can achieve a clearly chromatographic separation of complex chemicals in CDLs without prior fractionation, and thus can overcome the disadvantages of co-elution and serious peak overlap in GC/MS analysis, providing much more compositional information. With ultrahigh resolving power and mass accuracy, FT-ICR MS reveals a huge number of compositionally distinct compounds assigned to various chemical classes in CDLs. It shows excellent performance in resolving and characterizing higher-molecular, less volatile, and polar chemicals that cannot be detected by GC/MS and GC × GC-TOFMS. The application of GC × GC-TOFMS and FT-ICR MS to chemical characterization of CDLs is not as prevalent as that of petroleum and largely remains to be developed in many respects

  5. The delayed contribution of low and intermediate mass stars to chemical galactic enrichment: An analytical approach

    NASA Astrophysics Data System (ADS)

    Franco, I.; Carigi, L.

    2008-10-01

    We find a new analytical solution for the chemical evolution equations, taking into account the delayed contribution of all low and intermediate mass stars (LIMS) as one representative star that enriches the interstellar medium. This solution is built only for star formation rate proportional to the gas mass in a closed box model. We obtain increasing C/O and N/O ratios with increasing O/H, behavior impossible to match with the Instantaneous Recycling Approximation (IRA). Our results, obtained by two analytical equations, are very similar to those found by numerical models that consider the lifetimes of each star. This delayed model reproduces successfully the evolution of the C/O-O/H and Y - O relations in the solar vicinity. This analytical approximation is a useful tool to study the chemical evolution of elements produced by LIMS when a galactic chemical evolutionary code is not available.

  6. Chemical reactivity in matrix-assisted laser desorption/ionization mass spectrometry

    PubMed

    Enjalbal; Sauvagnat; Lamaty; Lazaro; Martinez; Mouchet; Roux; Aubagnac

    1999-01-01

    During the control of a multistep organic synthesis on a soluble polymer (PEG) by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, a chemical reactivity was encountered when the matrix was acidic, for the samples where the amino moiety of the anchored compounds was protected as a Schiff base. Such imine hydrolysis was proven to be solely mediated by the acidic matrix during analyses since the expected protected structures were detected when the experiments were duplicated with a non-acidic matrix. Even if MALDI mass spectrometry was found to be more convenient than electrospray ionization mass spectrometry for the monitoring of liquid phase organic syntheses, the chemical reactivity imparted by the use of a matrix must be taken into account to avoid erroneous spectra interpretations. Copyright 1999 John Wiley & Sons, Ltd.

  7. Mass and metallicity requirement in stellar models for galactic chemical evolution applications

    NASA Astrophysics Data System (ADS)

    Côté, Benoit; West, Christopher; Heger, Alexander; Ritter, Christian; O'Shea, Brian W.; Herwig, Falk; Travaglio, Claudia; Bisterzo, Sara

    2016-12-01

    We used a one-zone chemical evolution model to address the question of how many masses and metallicities are required in grids of massive stellar models in order to ensure reliable galactic chemical evolution predictions. We used a set of yields that includes seven masses between 13 and 30 M⊙, 15 metallicities between 0 and 0.03 in mass fraction, and two different remnant mass prescriptions. We ran several simulations where we sampled subsets of stellar models to explore the impact of different grid resolutions. Stellar yields from low- and intermediate-mass stars and from Type Ia supernovae have been included in our simulations, but with a fixed grid resolution. We compared our results with the stellar abundances observed in the Milky Way for O, Na, Mg, Si, Ca, Ti, and Mn. Our results suggest that the range of metallicity considered is more important than the number of metallicities within that range, which only affects our numerical predictions by about 0.1 dex. We found that our predictions at [Fe/H] ≲ -2 are very sensitive to the metallicity range and the mass sampling used for the lowest metallicity included in the set of yields. Variations between results can be as high as 0.8 dex. At higher [Fe/H], we found that the required number of masses depends on the element of interest and on the remnant mass prescription. With a monotonic remnant mass prescription where every model explodes as a core-collapse supernova, the mass resolution induces variations of 0.2 dex on average. But with a remnant mass prescription that includes islands of non-explodability, the mass resolution can cause variations of about 0.2-0.7 dex depending on the choice of the lower limit of the metallicity range. With such a remnant mass prescription, explosive or non-explosive models can be missed if not enough masses are selected, resulting in over- or underestimations of the mass ejected by massive stars.

  8. Binary-Encounter-Bethe ionisation cross sections for simulation of DNA damage by the direct effect of ionising radiation.

    PubMed

    Plante, I; Cucinotta, F A

    2015-09-01

    DNA damage is of crucial importance in the understanding of the effects of ionising radiation. To refine existing DNA damage models, an approach using the Binary-Encounter-Bethe (BEB) cross sections was developed. The differential cross sections for ionisation of the molecular orbitals of the DNA bases, sugars and phosphates are calculated using the electron binding energy, the mean kinetic energy and the occupancy number of each orbital as parameters. The resulting cross section has an analytic form which is quite convenient to use for Monte-Carlo codes that randomly sample the energy loss occurring during an ionisation event. We also describe an algorithm to simulate the interactions of electrons with DNA in the radiation transport code RITRACKS using the integrated BEB cross section for the bases, sugar and phosphates.

  9. A micro-mapping strategy to investigate mechanical and chemical mass transport in migmatite

    NASA Astrophysics Data System (ADS)

    Lanari, Pierre; Riel, Nicolas

    2016-04-01

    Migmatites are fantastic objects to study both mechanical and chemical mass transport occurring at mm to cm-scale. However, migmatitic outcrops are the result of complex space and time interactions between (i) melt producing reactions, (ii) melt gain/loss and (iii) retrograde reactions. This succession of events is recorded in the minerals and microstructures of migmatites, and accounts for their apparent complexity. In order to explore the controlling parameters of these chemico-mechanical mass transport, it is thus necessary to characterize in great details the compositional changes between the different migmatitic domains, such as between leucosome and residuum. In this contribution we show how suitable local effective bulk (LEB) compositions can be derived by means of standardized microprobe X-ray images, using the program XMapTools. For chemically heterogeneous samples, such as migmatites, these LEB allow to forward model the stable mineral assemblages for each domain. Those thermodynamic models are used to investigate the conditions of leucosome-residuum separation. The studied sample is a metapelite embedded within a metasedimentary xenolith in the Marcabeli pluton, El Oro Complex, Ecuador. The sample exhibits complex mineral patterns due to local melt redistribution (at mm to cm-scale). Such physical mass transport involves major changes that affect the local chemical composition observed today. At the same time gradients in chemical potential can be established between adjacent domains such as residuum and leucosome, thus triggering chemical interaction. Diffusive transport between domains aims to reduce such chemical potential gradients. Along a modelled P-T path the chemical and mineralogical evolution of micro-domains can be reconstructed for (at least the reactive parts of) the crystallization history.

  10. An experimental and theoretical study of core-valence double ionisation of acetaldehyde (ethanal).

    PubMed

    Zagorodskikh, S; Vapa, M; Vahtras, O; Zhaunerchyk, V; Mucke, M; Eland, J H D; Squibb, R J; Linusson, P; Jänkälä, K; Ågren, H; Feifel, R

    2016-01-28

    Core-valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique. We use this molecule as a testbed for analyzing core-valence spectra by means of quantum chemical calculations of transition energies. These theoretical approaches range from two simple models, one based on orbital energies corrected by core valence interaction and one based on the equivalent core approximation, to a systematic series of quantum chemical electronic structure methods of increasing sophistication. The two simple models are found to provide a fast orbital interpretation of the spectra, in particular in the low energy parts, while the coverage of the full spectrum is best fulfilled by correlated models. CASPT2 is the most sophisticated model applied, but considering precision as well as computational costs, the single and double excitation configuration interaction model seems to provide the best option to analyze core-valence double hole spectra.

  11. In situ analysis of Titan's tholins by Laser 2 steps Desorption Ionisation

    NASA Astrophysics Data System (ADS)

    Benilan, Y.; Carrasco, N.; Cernogora, G.; Gazeau, M.; Mahjoub, A.; Szopa, C.; Schwell, M.

    2013-12-01

    The main objective of the whole project developed in collaboration (LISA/LATMOS) is to provide a better understanding of the chemical composition of Titan aerosols laboratory analogs, called tholins, and thereby of their formation pathways. The tholins are produced in the PAMPRE reactor (French acronyme for Aerosols Microgravity Production by Reactives Plasmas) developed at LATMOS. These tholins are generated in levitation (wall effects are thus limited) in a low pressure radiofrequency plasma. Up to now, the determination of the physical and chemical properties of these tholins was achieved after their collection and ex-situ analysis by several methods. Their bulk composition was then determined but their insoluble part is still unknown. Other studies were performed after the transfer of the soluble part of the aerosols to different analytical instruments. Therefore, possible artifacts could have influenced the results. We present the SMARD (a French acronym for Mass Spectrometry of Aerosols by InfraRed Laser Desorption) program. A challenging issue of our work is to perform the soluble and unsoluble parts of PAMPRE tholins' analysis in real time and in situ. The coupling of the PAMPRE reactor to a unique instrument (Single Particle Laser Ablation Mass Spectrometry) developed at LISA should allow determining in real time and in situ the characteristics (chemical composition together with granulometry) of the nanometric aerosols. The later are introduced in the analytical instrument using an aerodynamic lens device. Their detection and aerodynamic diameter are determined using two continuous diode lasers operating at λ = 403 nm. Then, the L2DI (Laser 2 steps Desorption Ionisation) technique is used in order to access to the chemical composition of individual particles: they are vaporized using a 10 μm CO2 pulsed laser and the gas produced is then ionized by a 248 nm KrF Excimer laser. Finally, the molecular ions are analyzed by a 1 m linear time-of-flight mass

  12. The WISSH quasars project. I. Powerful ionised outflows in hyper-luminous quasars

    NASA Astrophysics Data System (ADS)

    Bischetti, M.; Piconcelli, E.; Vietri, G.; Bongiorno, A.; Fiore, F.; Sani, E.; Marconi, A.; Duras, F.; Zappacosta, L.; Brusa, M.; Comastri, A.; Cresci, G.; Feruglio, C.; Giallongo, E.; La Franca, F.; Mainieri, V.; Mannucci, F.; Martocchia, S.; Ricci, F.; Schneider, R.; Testa, V.; Vignali, C.

    2017-02-01

    Models and observations suggest that both the power and effects of AGN feedback should be maximised in hyper-luminous (LBol > 1047 erg s-1) quasars, i.e. objects at the brightest end of the AGN luminosity function. In this paper, we present the first results of a multiwavelength observing programme, focusing on a sample of WISE/SDSS selected hyper-luminous (WISSH) broad-line quasars at z ≈ 1.5-5. The WISSH quasars project has been designed to reveal the most energetic AGN-driven outflows, estimate their occurrence at the peak of quasar activity, and extend the study of correlations between outflows and nuclear properties up to poorly investigated, extreme AGN luminosities, i.e. LBol 1047 - 1048 erg s-1. We present near-infrared, long-slit LBT/LUCI1 spectroscopy of five WISSH quasars at z ≈ 2.3 - 3.5, showing prominent [OIII] emission lines with broad (FWHM 1200-2200 km s-1) and skewed profiles. The luminosities of these broad [OIII] wings are the highest measured so far, with L[OIII]broad ≳ 5 × 1044 erg s-1, and reveal the presence of powerful ionised outflows with associated mass outflow rates Ṁ ≳ 1700M⊙ yr-1 and kinetic powers Ėkin ≳ 1045 erg s-1. Although these estimates are affected by large uncertainties because of the use of [OIII] as a tracer of ionised outflows and the very basic outflow model adopted here, these results suggest that in our hyper-luminous targets the AGN is highly efficient at pushing large amounts of ionised gas outwards. Furthermore, the mechanical outflow luminosities measured for WISSH quasars correspond to higher percentages ( 1-3%) of LBol than those derived for AGN with lower LBol. Our targets host very massive (MBH ≳ 2 × 109M⊙) black holes that are still accreting at a high rate (i.e. a factor of 0.4-3 of the Eddington limit). These findings clearly demonstrate that WISSH quasars offer the opportunity to probe the extreme end of both luminosity and supermassive black holes (SMBH) mass functions and revealing

  13. Combination of Raman Spectroscopy and Mass Spectrometry for Online Chemical Analysis.

    PubMed

    Meher, Anil Kumar; Chen, Yu-Chie

    2016-09-20

    Mass spectrometry (MS) and Raman spectroscopy are complementary analytical techniques used to provide information related to chemical structures and functional groups of target analytes. Each instrument provides specific chemical information. If these two analytical tools are coupled online, comprehensive structural information can be simultaneously collected from the analytes of interest without losing any important chemical information. Nevertheless, exploring a suitable interface for coupling of these analytical tools, which are governed with different operation principles, remains challenging. In this study, we used a small piece of tissue paper as an interface for hyphenating a Raman spectroscope and a mass spectrometer online. The paper played multiroles as sample loading substrate and an emitter to generate electrospray. Furthermore, it can facilitate surface-enhanced Raman spectroscopic analysis to improve analyte signals in Raman spectra. A sample droplet was placed on the tissue paper located close to the laser of the Raman spectroscope and the inlet of mass spectrometer. Raman spectra were first collected by the Raman spectroscope through laser irradiation followed by generation of electrospray on the edge of the paper for MS analysis. Positional isomers were used as model samples to demonstrate the effectiveness of the hyphenated analytical tool in distinguishing isomers. The feasibility of using this Raman-MS hyphenated technique for monitoring chemical reactions online in real time was also investigated.

  14. Water mass properties and chemical signatures in the central Mediterranean region

    NASA Astrophysics Data System (ADS)

    Astraldi, M.; Conversano, F.; Civitarese, G.; Gasparini, G. P.; Ribera d'Alcalà, M.; Vetrano, A.

    2002-06-01

    During the last 15 years, the knowledge of Mediterranean physical dynamics as well as of atmospheric forcing underwent a tremendous improvement because of the action within several international programs and the development of remote sensing and modelling approaches. Curiously, it is still very difficult to build up a climatological database for chemical and basic biological parameters for the whole basin because most of the data published in the open literature were preferentially related to meso- to small-scale processes. Within the European Union project Mass Transfer and Ecosystem Response (MATER), systematic measurements of routine chemical parameters, such as dissolved oxygen and nutrients, have been conducted. They will fill the existing gap between physical and chemical information. In this paper, we analyze the hydrographic data from a cruise conducted in the fall 1996 in the Central Mediterranean region and report, for the first time, on oxygen and nutrient concentrations, ranges and distributions. The joint analysis of T- S properties and chemical data also allows a better definition of water mass characteristics in this crucial area and hints at basic mechanisms relevant to water mass transformation and biological production in the basin.

  15. Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

    PubMed

    Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

    2007-08-15

    Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs.

  16. On-line Monitoring of Continuous Flow Chemical Synthesis Using a Portable, Small Footprint Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Bristow, Tony W. T.; Ray, Andrew D.; O'Kearney-McMullan, Anne; Lim, Louise; McCullough, Bryan; Zammataro, Alessio

    2014-10-01

    For on-line monitoring of chemical reactions (batch or continuous flow), mass spectrometry (MS) can provide data to (1) determine the fate of starting materials and reagents, (2) confirm the presence of the desired product, (3) identify intermediates and impurities, (4) determine steady state conditions and point of completion, and (5) speed up process optimization. Recent developments in small footprint atmospheric pressure ionization portable mass spectrometers further enable this coupling, as the mass spectrometer can be easily positioned with the reaction system to be studied. A major issue for this combination is the transfer of a sample that is representative of the reaction and also compatible with the mass spectrometer. This is particularly challenging as high concentrations of reagents and products can be encountered in organic synthesis. The application of a portable mass spectrometer for on-line characterization of flow chemical synthesis has been evaluated by coupling a Microsaic 4000 MiD to the Future Chemistry Flow Start EVO chemistry system. Specifically, the Hofmann rearrangement has been studied using the on-line mass spectrometry approach. Sample transfer from the flow reactor is achieved using a mass rate attenuator (MRA) and a sampling make-up flow from a high pressure pump. This enables the appropriate sample dilution, transfer, and preparation for electrospray ionization. The capability of this approach to provide process understanding is described using an industrial pharmaceutical process that is currently under development. The effect of a number of key experimental parameters, such as the composition of the sampling make-up flow and the dilution factor on the mass spectrometry data, is also discussed.

  17. The Influence of Environment on the Chemical Evolution in Low-mass Galaxies

    NASA Astrophysics Data System (ADS)

    Liu, Yiqing; Ho, Luis C.; Peng, Eric

    2016-10-01

    The mean alpha-to-iron abundance ratio ([α/Fe]) of galaxies is sensitive to the chemical evolution processes at early time, and it is an indicator of star formation timescale ({τ }{SF}). Although the physical reason remains ambiguous, there is a tight relation between [α/Fe] and stellar velocity dispersion (σ) among massive early-type galaxies (ETGs). However, no work has shown convincing results as to how this relation behaves at low masses. We assemble 15 data sets from the literature and build a large sample that includes 192 nearby low-mass (18\\lt σ \\lt 80 km s-1) ETGs. We find that the [α/Fe]-σ relation generally holds for low-mass ETGs, except in extreme environments. Specifically, in normal galaxy cluster environments, the [α/Fe]-σ relation and its intrinsic scatter are, within uncertainties, similar for low-mass and high-mass ETGs. However, in the most massive relaxed galaxy cluster in our sample, the zero point of the relation is higher and the intrinsic scatter is significantly larger. By contrast, in galaxy groups the zero point of the relation offsets in the opposite direction, again with substantial intrinsic scatter. The elevated [α/Fe] of low-mass ETGs in the densest environments suggests that their star formation was quenched earlier. For the low-mass ETGs in the lowest-density environments, we suggest that their more extended star formation histories suppressed their average [α/Fe]. The large scatter in [α/Fe] may reflect stochasticity in the chemical evolution of low-mass galaxies.

  18. Modeling and managing toxic chemicals: The Lake Michigan mass balance study

    SciTech Connect

    Endicott, D.D.; Richardson, W.L.

    1995-12-31

    The control and management of anthropogenic chemicals in the Great Lakes is an issue of great concern for 2 nations, 9 states and provinces, and 33 million people. As loadings from identified sources have been reduced, sometimes dramatic declines in toxic chemical concentrations have been observed to follow. However, human health and ecological effects from toxic chemicals remain topics of concern. There is also scientific debate regarding what factors control current toxic chemical concentrations in biotic and abiotic components of the Great lakes ecosystem. To address this latter issue, mathematical models are being developed to simulate the sources, transport, bioavailability, and bioaccumulation of four target chemicals (atrazine, mercury, PCBs, and trans-nonachlor). Preliminary modeling assessment by the authors suggested that PCB concentrations in Lake Michigan lake trout would remain greater than 1 mg/kg, even if all point and nonpoint sources in the watershed were eliminated. 2 factors control this result: (1) atmospheric sources are the largest PCB load component, and (2) the release of PCBs from the lake sediments by resuspension represents a huge internal mass flux. However, current data does not allow accurate estimation of either quantity. Because of the major ecological and economical consequences of decisions based upon the mass balance assessment, the modeling results require scientific confirmation.

  19. Characterisation of photoaffinity-based chemical probes using fluorescence imaging and native state mass spectrometry.

    PubMed

    Teruya, Kanae; Rankin, Gregory; Chrysanthopoulos, Panagiotis; Tonissen, Kathryn; Poulsen, Sally-Ann

    2017-02-08

    Chemical probes are small molecule reagents used by researchers for labeling and detection of biomolecules. We present the design, synthesis and characterisation of a panel of eleven structurally diverse photoaffinity labeling (PAL) probes as research tools for labeling the model enzyme carbonic anhydrase (CA) in challenging environments, including protein mixtures and cell lysates. We target ubiquitous CA II as well as the two cancer associated CAs (CA IX and CA XII), which are high priority as potential biomarkers of aggressive and/or multidrug resistant cancer. We utilize an atypical biophysical approach, native state mass spectrometry, to monitor the initial protein:probe binding and subsequent UV crosslinking efficiency of the protein:probe complex. This mass spectrometry methodology represents a novel approach for chemical probe optimization and development that may have broader applications to chemical probe characterization beyond this study. This also represents one of the first studies, to our knowledge, where a comprehensive set of PAL probes was used to establish the relationship between probe structure, noncovalent protein:probe binding and covalent protein:probe crosslinking efficiency. Our results demonstrate the benefits of a comprehensive analysis of chemical probe structure-activity relationships to support the development of optimum chemical probes.

  20. Chemical characterization of the early evolutionary phases of high-mass star-forming regions

    NASA Astrophysics Data System (ADS)

    Gerner, Thomas

    2014-10-01

    The formation of high-mass stars is a very complex process and up to date no comprehensive theory about it exists. This thesis studies the early stages of high-mass star-forming regions and employs astrochemistry as a tool to probe their different physical conditions. We split the evolutionary sequence into four observationally motivated stages that are based on a classification proposed in the literature. The sequence is characterized by an increase of the temperatures and densities that strongly influences the chemistry in the different stages. We observed a sample of 59 high-mass star-forming regions that cover the whole sequence and statistically characterized the chemical compositions of the different stages. We determined average column densities of 18 different molecular species and found generally increasing abundances with stage. We fitted them for each stage with a 1D model, such that the result of the best fit to the previous stage was used as new input for the following. This is a unique approach and allowed us to infer physical properties like the temperature and density structure and yielded a typical chemical lifetime for the high-mass star-formation process of 1e5 years. The 18 analyzed molecular species also included four deuterated molecules whose chemistry is particularly sensitive to thermal history and thus is a promising tool to infer chemical ages. We found decreasing trends of the D/H ratios with evolutionary stage for 3 of the 4 molecular species and that the D/H ratio depends more on the fraction of warm and cold gas than on the total amount of gas. That indicates different chemical pathways for the different molecules and confirms the potential use of deuterated species as chemical age indicators. In addition, we mapped a low-mass star forming region in order to study the cosmic ray ionization rate, which is an important parameter in chemical models. While in chemical models it is commonly fixed, we found that it ! strongly varies with

  1. [In-hospital management of victims of chemical weapons of mass destruction].

    PubMed

    Barelli, Alessandro; Gargano, Flavio; Proietti, Rodolfo

    2005-01-01

    Emergency situations caused by chemical weapons of mass destruction add a new dimension of risk to those handling and treating casualties. The fundamental difference between a hazardous materials incident and conventional emergencies is the potential for risk from contamination to health care professionals, patients, equipment and facilities of the Emergency Department. Accurate and specific guidance is needed to describe the procedures to be followed by emergency medical personnel to safely care for a patient, as well as to protect equipment and people. This review is designed to familiarize readers with the concepts, terminology and key operational considerations that affect the in-hospital management of incidents by chemical weapons.

  2. Study of mass consistency LES/FDF techniques for chemically reacting flows

    NASA Astrophysics Data System (ADS)

    Celis, Cesar; Figueira da Silva, Luís Fernando

    2015-07-01

    A hybrid large eddy simulation/filtered density function (LES/FDF) approach is used for studying chemically reacting flows with detailed chemistry. In particular, techniques utilised for ensuring a mass consistent coupling between LES and FDF are discussed. The purpose of these techniques is to maintain a correct spatial distribution of the computational particles representing specified amounts of fluid. A particular mass consistency technique due to Y.Z. Zhang and D.C. Haworth (A general mass consistency algorithm for hybrid particle/finite-volume PDF methods, J. Comput. Phys. 194 (2004), pp. 156-193) and their associated algorithms are implemented in a pressure-based computational fluid dynamics code suitable for the simulation of variable density flows, representative of those encountered in actual combustion applications. To assess the effectiveness of the referenced technique for enforcing LES/FDF mass consistency, two- and three-dimensional simulations of a temporal mixing layer using detailed and reduced chemistry mechanisms are carried out. The parametric analysis performed focuses on determining the influence on the level of mass consistency errors of parameters such as the initial number of particles per cell and the initial density ratio of the mixing layers. Particular emphasis is put on the computational burden that represents the use of such a mass consistency technique. The results show the suitability of this type of technique for ensuring the mass consistency required when utilising hybrid LES/FDF approaches. The level of agreement of the computed results with experimental data is also illustrated.

  3. Ultrasensitive detection of explosives and chemical warfare agents by low-pressure photoionization mass spectrometry.

    PubMed

    Sun, Wanqi; Liang, Miao; Li, Zhen; Shu, Jinian; Yang, Bo; Xu, Ce; Zou, Yao

    2016-08-15

    On-spot monitoring of threat agents needs high sensitive instrument. In this study, a low-pressure photoionization mass spectrometer (LPPI-MS) was employed to detect trace amounts of vapor-phase explosives and chemical warfare agent mimetics under ambient conditions. Under 10-s detection time, the limits of detection of 2,4-dinitrotoluene, nitrotoluene, nitrobenzene, and dimethyl methyl phosphonate were 30, 0.5, 4, and 1 parts per trillion by volume, respectively. As compared to those obtained previously with PI mass spectrometric techniques, an improvement of 3-4 orders of magnitude was achieved. This study indicates that LPPI-MS will open new opportunities for the sensitive detection of explosives and chemical warfare agents.

  4. Safe management of mass fatalities following chemical, biological, and radiological incidents.

    PubMed

    Baker, David J; Jones, Kelly A; Mobbs, Shelly F; Sepai, Ovnair; Morgan, Dilys; Murray, Virginia S G

    2009-01-01

    Contaminated mass fatalities following the release of chemical, biological, or radiological agents pose a potential major health hazard. A United Kingdom government investigation has identified a number of areas of risk. This paper presents an outline of the findings of the study and describes specific pathways for the management of contaminated and non-contaminated fatalities. Factors determining the choice between cremation and burial are discussed. Effective decontamination remains a neglected area of study for both fatalities and casualties.

  5. Radioimmunoassay and chemical ionization/mass spectrometry compared for plasma cortisol determination

    SciTech Connect

    Lindberg, C.; Johnson, S.; Hedner, P.; Gustafsson, A.

    1982-01-01

    A method is described for determination of cortisol in plasma and urine, based on chemical ionization/mass spectrometry with deuterium-labeled cortisol as the internal standard. The within-run precision (CV) was 2.5-5.7%, the between-run precision 4.6%. Results by this method were compared with those by a radioimmunological method (RIANEN Cortisol, New England Nuclear) for 395 plasma samples. The latter method gave significantly higher (approx. 25%) cortisol values.

  6. Real-time monitoring of volatile organic compounds using chemical ionization mass spectrometry

    DOEpatents

    Mowry, Curtis Dale; Thornberg, Steven Michael

    1999-01-01

    A system for on-line quantitative monitoring of volatile organic compounds (VOCs) includes pressure reduction means for carrying a gaseous sample from a first location to a measuring input location maintained at a low pressure, the system utilizing active feedback to keep both the vapor flow and pressure to a chemical ionization mode mass spectrometer constant. A multiple input manifold for VOC and gas distribution permits a combination of calibration gases or samples to be applied to the spectrometer.

  7. Chemical and Physical Characterization of Collapsing Low-mass Prestellar Dense Cores

    NASA Astrophysics Data System (ADS)

    Hincelin, U.; Commerçon, B.; Wakelam, V.; Hersant, F.; Guilloteau, S.; Herbst, E.

    2016-05-01

    The first hydrostatic core, also called the first Larson core, is one of the first steps in low-mass star formation as predicted by theory. With recent and future high-performance telescopes, the details of these first phases are becoming accessible, and observations may confirm theory and even present new challenges for theoreticians. In this context, from a theoretical point of view, we study the chemical and physical evolution of the collapse of prestellar cores until the formation of the first Larson core, in order to better characterize this early phase in the star formation process. We couple a state-of-the-art hydrodynamical model with full gas-grain chemistry, using different assumptions for the magnetic field strength and orientation. We extract the different components of each collapsing core (i.e., the central core, the outflow, the disk, the pseudodisk, and the envelope) to highlight their specific physical and chemical characteristics. Each component often presents a specific physical history, as well as a specific chemical evolution. From some species, the components can clearly be differentiated. The different core models can also be chemically differentiated. Our simulation suggests that some chemical species act as tracers of the different components of a collapsing prestellar dense core, and as tracers of the magnetic field characteristics of the core. From this result, we pinpoint promising key chemical species to be observed.

  8. Chemical composition and mass closure of ambient PM10 at urban sites

    NASA Astrophysics Data System (ADS)

    Terzi, Eleni; Argyropoulos, George; Bougatioti, Aikaterini; Mihalopoulos, Nikolaos; Nikolaou, Kostas; Samara, Constantini

    2010-06-01

    The chemical composition of PM10 was studied during summer and winter sampling campaigns conducted at two different urban sites in the city of Thessaloniki, Greece (urban-traffic, UT and urban-industrial, UI). PM10 samples were chemically analysed for minerals (Si, Al, Ca, Mg, Fe, Ti, K), trace elements (Cd, Cr, Cu, Mn, Pb, V, Zn, Te, Co, Ni, Se, Sr, As, and Sb), water-soluble ions (Cl -, NO 3-, SO 42-, Na +, K +, NH 4+, Ca 2+, Mg 2+) and carbonaceous compounds (OC, EC). Spatial variations of atmospheric concentrations showed significantly higher levels of minerals, some trace metals and TC at the UI site, while at the UT site significantly higher levels of elements like Cd, Ba, Sn, Sb and Te were observed. Crustal elements, excepting Ca at the UI site, did not exhibit significant seasonal variations at any site pointing to constant emissions throughout the year. In order to reconstruct the particle mass, the determined components were classified into six classes as follows: mineral matter (MIN), trace elements (TE), organic matter (OM), elemental carbon (EC), sea salt (SS) and secondary inorganic aerosol (SIA). Good correlations with slopes close to 1 were found between chemically determined and gravimetrically measured PM10 masses for both sites. According to the chemical mass closure obtained, the major components of PM10 at both sites were MIN (soil-derived compounds), followed by OM and SIA. The fraction unaccounted for by chemical analysis comprised on average 8% during winter and 15% during summer at the urban-industrial site, while at the urban-traffic site the percentages were 21.5% in winter and 4.8% in summer.

  9. Toward a Chemical Evolutionary Sequence in High-Mass Star Formation

    NASA Astrophysics Data System (ADS)

    Gerner, Thomas; Beuther, Henrik; Semenov, Dmitry; Linz, Hendrik; Vasyunina, Tatiana; Henning, Thomas

    Understanding the chemical evolution of young (high-mass) star-forming regions is a central topic in star formation research. The chemistry plays two main roles here: to study the evolution from simple to complex molecules, and to investigate the underlying physical processes. With these aims in mind, we observed a diverse sample of 60 high-mass star-forming regions in different evolutionary stages. In the early phase, quiescent Infrared Dark Clouds (IRDCs), consisting of cold and dense gas and dust, and emitting mainly at (sub-)millimeter wavelength, are formed. In the next phase, the so called High Mass Protostellar Objects (HMPOs) form, which host a central, likely still accreting protostar and already show emission at mid-infrared wavelengths. In the Hot Molecular Core phase (HMC) the central source heats up the surrounding environment, evaporating molecular-rich ices, which gives rise to a rich chemistry leading to complex molecules such as long carbon chains. Finally the UV-radiation from the embedded protostars ionizes the gas around and forms an Ultra Compact HII (UCHII) region. In these objects many of the previously formed complex molecules are not longer detected as they got destroyed by the ionizing radiation. For our observations, we used the IRAM 30m telescope with the total bandpass of 16 GHz and good spectral resolution (˜0.3/0.7 km/s at 1/3 mm). We derived their large-scale chemical abundances, assuming LTE and optically thin emission. To set these results into context, we model the chemical evolution in such environments with a state-of-the-art chemical model. This enables us to put constraints on the chemical evolution, the age and parameters such as the temperature and the density of the molecular clouds.

  10. Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2006-04-30

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

  11. GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

    SciTech Connect

    Smith, JN

    2016-04-01

    The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

  12. Fragment formula calculator (FFC): determination of chemical formulas for fragment ions in mass spectrometric data.

    PubMed

    Wegner, André; Weindl, Daniel; Jäger, Christian; Sapcariu, Sean C; Dong, Xiangyi; Stephanopoulos, Gregory; Hiller, Karsten

    2014-02-18

    The accurate determination of mass isotopomer distributions (MID) is of great significance for stable isotope-labeling experiments. Most commonly, MIDs are derived from gas chromatography/electron ionization mass spectrometry (GC/EI-MS) measurements. The analysis of fragment ions formed during EI, which contain only specific parts of the original molecule can provide valuable information on the positional distribution of the label. The chemical formula of a fragment ion is usually applied to derive the correction matrix for accurate MID calculation. Hence, the correct assignment of chemical formulas to fragment ions is of crucial importance for correct MIDs. Moreover, the positional distribution of stable isotopes within a fragment ion is of high interest for stable isotope-assisted metabolomics techniques. For example, (13)C-metabolic flux analyses ((13)C-MFA) are dependent on the exact knowledge of the number and position of retained carbon atoms of the unfragmented molecule. Fragment ions containing different carbon atoms are of special interest, since they can carry different flux information. However, the process of mass spectral fragmentation is complex, and identifying the substructures and chemical formulas for these fragment ions is nontrivial. For that reason, we developed an algorithm, based on a systematic bond cleavage, to determine chemical formulas and retained atoms for EI derived fragment ions. Here, we present the fragment formula calculator (FFC) algorithm that can calculate chemical formulas for fragment ions where the chemical bonding (e.g., Lewis structures) of the intact molecule is known. The proposed algorithm is able to cope with general molecular rearrangement reactions occurring during EI in GC/MS measurements. The FFC algorithm is able to integrate stable isotope labeling experiments into the analysis and can automatically exclude candidate formulas that do not fit the observed labeling patterns.1 We applied the FFC algorithm to create

  13. Evaluation of C60 secondary ion mass spectrometry for the chemical analysis and imaging of fingerprints.

    PubMed

    Sisco, Edward; Demoranville, Leonard T; Gillen, Greg

    2013-09-10

    The feasibility of using C60(+) cluster primary ion bombardment secondary ion mass spectrometry (C60(+) SIMS) for the analysis of the chemical composition of fingerprints is evaluated. It was found that C60(+) SIMS could be used to detect and image the spatial localization of a number of sebaceous and eccrine components in fingerprints. These analyses were also found to not be hindered by the use of common latent print powder development techniques. Finally, the ability to monitor the depth distribution of fingerprint constituents was found to be possible - a capability which has not been shown using other chemical imaging techniques. This paper illustrates a number of strengths and potential weaknesses of C60(+) SIMS as an additional or complimentary technique for the chemical analysis of fingerprints.

  14. The synergistic effect of ultrasound and chemical penetration enhancers on chorioamnion mass transport.

    PubMed

    Azagury, Aharon; Khoury, Luai; Adato, Yair; Wolloch, Lior; Ariel, Ilana; Hallak, Mordechai; Kost, Joseph

    2015-02-28

    In our previous study we proposed the use of chemical penetration enhancers for noninvasive detection of fetus abnormalities that can also be utilized for direct fetal drug delivery. In an attempt to further increase the mass transport rate across the amniotic membrane, thus shortening the procedure and improving the applicability of the proposed procedure, the effect and mechanism of combining ultrasound exposure with chemical penetration enhancers' application were assessed. The combined effect was evaluated in vitro on post-delivery human amniotic membrane and ex vivo on rat's whole amniotic sac. Ultrasound effect has been assessed by dye experiments using a customized image analysis program. Additional insights of ultrasound effect's mechanism on biological membranes are presented. Previously we have determined that chemical penetration enhancers affect the fetal membranes via two mechanisms termed as 'extractors' and 'fluidizers'. In this study, we found that combining ultrasound with a 'fluidizer' CPE (e.g. bupivacaine) results in a synergistic enhancement (90-fold) of fetal membrane's mass transport, while combining ultrasound with 'extractors' (e.g. ethanol and NMP) results in an antagonistic effect. The combined procedure is faster and gain greater accuracy than the applications of sole chemical penetration enhancers.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  16. Advancements in mass spectrometry for biological samples: Protein chemical cross-linking and metabolite analysis of plant tissues

    SciTech Connect

    Klein, Adam

    2015-01-01

    This thesis presents work on advancements and applications of methodology for the analysis of biological samples using mass spectrometry. Included in this work are improvements to chemical cross-linking mass spectrometry (CXMS) for the study of protein structures and mass spectrometry imaging and quantitative analysis to study plant metabolites. Applications include using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to further explore metabolic heterogeneity in plant tissues and chemical interactions at the interface between plants and pests. Additional work was focused on developing liquid chromatography-mass spectrometry (LC-MS) methods to investigate metabolites associated with plant-pest interactions.

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

    SciTech Connect

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

    2013-01-01

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

  18. Stagnation point flow and mass transfer with chemical reaction past a stretching/shrinking cylinder.

    PubMed

    Najib, Najwa; Bachok, Norfifah; Arifin, Norihan Md; Ishak, Anuar

    2014-02-26

    This paper is about the stagnation point flow and mass transfer with chemical reaction past a stretching/shrinking cylinder. The governing partial differential equations in cylindrical form are transformed into ordinary differential equations by a similarity transformation. The transformed equations are solved numerically using a shooting method. Results for the skin friction coefficient, Schmidt number, velocity profiles as well as concentration profiles are presented for different values of the governing parameters. Effects of the curvature parameter, stretching/shrinking parameter and Schmidt number on the flow and mass transfer characteristics are examined. The study indicates that dual solutions exist for the shrinking cylinder but for the stretching cylinder, the solution is unique. It is observed that the surface shear stress and the mass transfer rate at the surface increase as the curvature parameter increases.

  19. 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

    2016-07-05

    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.

  20. Higher sensitivity secondary ion mass spectrometry of biological molecules for high resolution, chemically specific imaging.

    PubMed

    McDonnell, Liam A; Heeren, Ron M A; de Lange, Robert P J; Fletcher, Ian W

    2006-09-01

    To expand the role of high spatial resolution secondary ion mass spectrometry (SIMS) in biological studies, numerous developments have been reported in recent years for enhancing the molecular ion yield of high mass molecules. These include both surface modification, including matrix-enhanced SIMS and metal-assisted SIMS, and polyatomic primary ions. Using rat brain tissue sections and a bismuth primary ion gun able to produce atomic and polyatomic primary ions, we report here how the sensitivity enhancements provided by these developments are additive. Combined surface modification and polyatomic primary ions provided approximately 15.8 times more signal than using atomic primary ions on the raw sample, whereas surface modification and polyatomic primary ions yield approximately 3.8 and approximately 8.4 times more signal. This higher sensitivity is used to generate chemically specific images of higher mass biomolecules using a single molecular ion peak.

  1. Analytical technique to address terrorist threats by chemical weapons of mass destruction

    NASA Astrophysics Data System (ADS)

    Dempsey, Patrick M.

    1997-01-01

    Terrorism is no longer an issue without effect on the American mind. We now live with the same concerns and fears that have been commonplace in other developed and third world countries for a long time. Citizens of other countries have long lived with the specter of terrorism and now the U.S. needs to be concerned and prepared for terrorist activities.T he terrorist has the ability to cause great destructive effects by focusing their effort on unaware and unprepared civilian populations. Attacks can range from simple explosives to sophisticated nuclear, chemical and biological weapons. Intentional chemical releases of hazardous chemicals or chemical warfare agents pose a great threat because of their ready availability and/or ease of production, and their ability to cause widespread damage. As this battlefront changes from defined conflicts and enemies to unnamed terrorists, we must implement the proper analytical tools to provide a fast and efficient response. Each chemical uses in a terrorists weapon leaves behind a chemical signature that can be used to identify the materials involved and possibly lead investigators to the source and to those responsible. New tools to provide fast and accurate detection for battlefield chemical and biological agent attack are emerging. Gas chromatography/mass spectrometry (GC/MS) is one of these tools that has found increasing use by the military to respond to chemical agent attacks. As the technology becomes smaller and more portable, it can be used by law enforcement personnel to identify suspected terrorist releases and to help prepare the response; define contaminated areas for evacuation and safety concerns, identify the proper treatment of exposed or affected civilians, and suggest decontamination and cleanup procedures.

  2. Glioblastoma stem cells: radiobiological response to ionising radiations of different qualities.

    PubMed

    Pecchia, I; Dini, V; Ricci-Vitiani, L; Biffoni, M; Balduzzi, M; Fratini, E; Belli, M; Campa, A; Esposito, G; Cirrone, G; Romano, F; Stancampiano, C; Pelacchi, F; Pallini, R; Tabocchini, M A

    2015-09-01

    Glioblastoma multiforme (GBM) is the most common and malignant primary brain tumour, with very poor prognosis. The high recurrence rate and failure of conventional treatments are expected to be related to the presence of radio-resistant cancer stem cells (CSCs) inside the tumour mass. CSCs can both self-renew and differentiate into the heterogeneous lineages of cancer cells. Recent evidence showed a higher effectiveness of C-ions and protons in inactivating CSCs, suggesting a potential advantage of Hadrontherapy compared with conventional radiotherapy for GBM treatment. To investigate the mechanisms involved in the molecular and cellular responses of CSCs to ionising radiations, two GBM stem cell (GSC) lines, named lines 1 and 83, which were derived from patients with different clinical outcomes and having different metabolic profiles (as shown by NMR spectroscopy), were irradiated with (137)Cs photons and with protons or C-ions of 62 MeV u(-1) in the dose range of 5-40 Gy. The biological effects investigated were: cell death, cell cycle progression, and DNA damage induction and repair. Preliminary results show a different response to ionising radiation between the two GSC lines for the different end points investigated. Further experiments are in progress to consolidate the data and to get more insights on the influence of radiation quality.

  3. Chemical and sediment mass transfer in the Yamuna River — A tributary of the Ganges system

    NASA Astrophysics Data System (ADS)

    Jha, P. K.; Subramanian, V.; Sitasawad, R.

    1988-12-01

    Maximum mass transfer, in the Yamuna River takes place during the monsoon season. The sediment load constitutes 58-86% of the total load carried by the river depending upon the sites. Tributaries are chemically more active than the mainstream. The total load of the river seems to be controlled by lithology. At Allahabad, the Yamuna carries 42 × 10 6t dissolved chemical load and 64 × 10 6t sediment load to the Ganges river. The TSM/TDS ratio shows that upstream physical weathering is more dominant than chemical weathering. The negative relation between basin area and total erosion rate and the positive relation between the chemical and sediment erosion in the Yamuna basin is in agreement with the global trend. The average chemical erosion rate (165 t km -2yr -1) of the Yamuna is much higher than that of the Ganges and the Indian average. The total erosion rate (973 t km -2yr -1) is 1.7 times greater than that of the Ganges. Upstream the Yamuna removes 1.04 mm yr -1 of the basin surface; the removal rate decreases downstream to 0.19 mm yr -1 at Allahabad, the point of confluence with the Ganges.

  4. Evaluation of a pulse-discharge helium ionisation detector for the determination of neon concentrations by gas chromatography.

    PubMed

    Lasa, J; Mochalski, P; Pusz, J

    2004-05-07

    A pulse-discharge helium ionisation detector, PDHID (Valco, PD-D2-I) with sample introduced to the discharge zone is shown to be applicable for reliable determinations of neon by gas chromatography. The detection level of 80 pg was obtained, but the dependence between detector response and neon mass was non-linear. However, for the discharge gas doped with 33 ppm of neon, a linear response to the neon mass up to 10(-5) g and the detection level of 0.5 ng were obtained. The method can be used for measuring neon concentrations in groundwater systems for hydrogeological purposes.

  5. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    PubMed

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages.

  6. On-tissue chemical derivatization of 3-methoxysalicylamine for MALDI-imaging mass spectrometry

    PubMed Central

    Chacon, Almary; Zagol-Ikapitte, Irene; Amarnath, Venkataraman; Reyzer, Michelle L.; Oates, John A.; Caprioli, Richard M.; Boutaud, Olivier

    2011-01-01

    MALDI-imaging mass spectrometry (IMS) has been shown to be a powerful tool to study drug distributions in organ tissue as well as whole animal bodies. Nevertheless, not all drugs are amenable to MALDI while others may be limited by poor sensitivity poor sensitivity. The use of chemical derivatization to improve detection of small molecules by mass spectrometry techniques is well documented. To our knowledge, however, this approach has not been applied to direct tissue analysis of small organic molecules. In this manuscript, we demonstrate the use of on-tissue chemical derivatization of a small organic molecule, 3-methoxysalicylamine (3-MoSA) a scavenger of γ -ketoaldehydes. Derivatization of 3-MoSA with 1,1′-thiocarbonyldiimidazole (TCDI) results in an oxothiazolidine derivative which is detected with much greater sensitivity by MALDI than 3-MoSA itself. TCDI treatment of tissue from mice dosed with 3-MoSA allowed images to be obtained showing its spatial distribution as well as its pharmacokinetic profile in different organs. These images correlated well with results obtained from HPLC-MS/MS analyses of the same tissues. These results provide proof-of-concept that on-tissue chemical derivatization can be used to improve detection of a small organic molecule by MALDI-IMS. PMID:21834023

  7. Chemical characterization of synthetic cannabinoids by electrospray ionization FT-ICR mass spectrometry.

    PubMed

    Kill, Jade B; Oliveira, Izabela F; Tose, Lilian V; Costa, Helber B; Kuster, Ricardo M; Machado, Leandro F; Correia, Radigya M; Rodrigues, Rayza R T; Vasconcellos, Géssica A; Vaz, Boniek G; Romão, Wanderson

    2016-09-01

    The synthetic cannabinoids (SCs) represent the most recent advent of the new psychotropic substances (NPS) and has become popularly known to mitigate the effects of the Δ(9)-THC. The SCs are dissolved in organic solvents and sprayed in a dry herbal blend. However, little information is reported on active ingredients of SCs as well as the excipients or diluents added to the herbal blend. In this work, the direct infusion electrospray ionization Fourier transform ion cyclotron mass spectrometry technique (ESI-FT-ICR MS) was applied to explore the chemical composition of nine samples of herbal extract blends, where a total of 11 SCs (UR-144, JWH-073, XLR-11, JWH-250, JWH-122, AM-2201, AKB48, JWH-210, JWH-081, MAM-2201 and 5F-AKB48) were identified in the positive ionization mode, ESI(+), and other 44 chemical species (saturated and unsaturated fatty acids, sugars, flavonoids, etc.) were detected in the negative ionization mode, ESI(-). Additionally, CID experiments were performed, and fragmentation pathways were proposed to identify the connectivity of SCs. Thus, the direct infusion ESI-FT-ICR MS technique is a powerful tool in forensic chemistry that enables the rapid and unequivocal way for the determination of molecular formula, the degree of unsaturation (DBE-double bond equivalent) and exact mass (<1ppm) of a total of 55 chemical species without the prior separation step.

  8. Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices

    NASA Astrophysics Data System (ADS)

    Liu, Chengyuan; Yang, Jiuzhong; Wang, Jian; Hu, Yonghua; Zhao, Wan; Zhou, Zhongyue; Qi, Fei; Pan, Yang

    2016-10-01

    Extractive atmospheric pressure photoionization (EAPPI) mass spectrometry was designed for rapid qualitative and quantitative analysis of chemicals in complex matrices. In this method, an ultrasonic nebulization system was applied to sample extraction, nebulization, and vaporization. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion-molecule reactions, and were mass-analyzed by a high resolution time-of-flight mass spectrometer (TOF-MS). After careful optimization and testing with pure sample solution, EAPPI was successfully applied to the fast screening of capsules, soil, natural products, and viscous compounds. Analysis was completed within a few seconds without the need for preseparation. Moreover, the quantification capability of EAPPI for matrices was evaluated by analyzing six polycyclic aromatic hydrocarbons (PAHs) in soil. The correlation coefficients ( R 2 ) for standard curves of all six PAHs were above 0.99, and the detection limits were in the range of 0.16-0.34 ng/mg. In addition, EAPPI could also be used to monitor organic chemical reactions in real time.

  9. Chemical Diversity and Complexity of Scotch Whisky as Revealed by High-Resolution Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Kew, Will; Goodall, Ian; Clarke, David; Uhrín, Dušan

    2017-01-01

    Scotch Whisky is an important product, both culturally and economically. Chemically, Scotch Whisky is a complex mixture, which comprises thousands of compounds, the nature of which are largely unknown. Here, we present a thorough overview of the chemistry of Scotch Whisky as observed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Eighty-five whiskies, representing the majority of Scotch Whisky produced and sold, were analyzed by untargeted high-resolution mass spectrometry. Thousands of chemical formulae were assigned for each sample based on parts-per-billion mass accuracy of FT-ICR MS spectra. For the first time, isotopic fine structure analysis was used to confirm the assignment of high molecular weight CHOS species in Scotch Whisky. The assigned spectra were compared using a number of visualization techniques, including van Krevelen diagrams, double bond equivalence (DBE) plots, as well as heteroatomic compound class distributions. Additionally, multivariate analysis, including PCA and OPLS-DA, was used to interpret the data, with key compounds identified for discriminating between types of whisky (blend or malt) or maturation wood type. FT-ICR MS analysis of Scotch Whisky was shown to be of significant potential in further understanding of the complexity of mature spirit drinks and as a tool for investigating the chemistry of the maturation processes.

  10. Method to reduce chemical background interference in atmospheric pressure ionization liquid chromatography-mass spectrometry using exclusive reactions with the chemical reagent dimethyl disulfide.

    PubMed

    Guo, Xinghua; Bruins, Andries P; Covey, Thomas R

    2007-06-01

    The interference of chemical background ions (chemical noise) has been a problem since the inception of mass spectrometry. We present here a novel method to reduce the chemical noise in LC-MS based on exclusive gas-phase reactions with a reactive collision gas in a triple-quadrupole mass spectrometer. Combined with the zero neutral loss (ZNL) scan of a triple-quadrupole mass spectrometer, the reactive chemical noise ions can be removed because of shifts of mass-to-charge ratios from the original background ions. The test on various classes of compounds with different functional groups indicates a generic application of this technique in LC-MS. The preliminary results show that a reduction of the level of LC-MS base-peak chromatographic baseline by a factor up to 40 and an improvement of the signal-to-noise ratio by a factor up to 5-10 are achieved on both commercial and custom-modified triple-quadrupole LC-MS systems. Application is foreseen in both quantitative and qualitative trace analysis. It is expected that this chemical noise reduction technique can be optimized on a dedicated mass spectrometric instrumentation which incorporates both a chemical reaction cell for noise reduction and a collision stage for fragmentation.

  11. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    Chemical mass size distributions of aerosol particles were measured in the remote marine boundary layer over the central Arctic Ocean as part of the Atmospheric Research Program on the Arctic Ocean Expedition 1996 (AOE-96). An inertial impaction method was used to classify aerosol particles into different size classes for subsequent chemical analysis. The particle chemical composition was determined by ion chromatography and by the particle-induced X-ray emission technique. Continuous particle size spectra were extracted from the raw data using a data inversion method. Clear and varying modal structures for aerosols consisting of primary sea-salt particles or of secondary particles related to dimethyl sulfide emissions were found. Concentration levels of all modes decreased rapidly when the distance from open sea increased. In the submicrometer size range the major ions found by ion chromatography were sulfate, methane sulfonate, and ammonium. They had most of the time a clear Aitken mode and one or two accumulation modes, with aerodynamic mass median diameters around 0.1 μm, 0.3 μm, and between 0.5-1.0 μm, respectively. The overall submicron size distributions of these three ions were quite similar, suggesting that they were internally mixed over most of this size range. The corresponding modal structure was consistent with the mass size distributions derived from the particle number size distributions measured with a differential mobility particle sizer. The Aitken to accumulation mode mass ratio for nss-sulfate and MSA was substantially higher during clear skies than during cloudy periods. Primary sea-salt particles formed a mode with an aerodynamic mass median diameter around 2 μm. In general, the resulting continuous mass size distributions displayed a clear modal structure consistent with our understanding of the two known major source mechanisms. One is the sea-salt aerosol emerging from seawater by bubble bursting. The other is related to

  12. IEC standards for individual monitoring of ionising radiation.

    PubMed

    Voytchev, M; Ambrosi, P; Behrens, R; Chiaro, P

    2011-03-01

    This paper presents IEC/SC 45B 'Radiation protection instrumentation' and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  13. IEC STANDARDS FOR INDIVIDUAL MONITORING OF IONISING RADIATION

    SciTech Connect

    Voytchev, Miroslav; Ambrosi, P.; Behrens, R.; Chiaro Jr, Peter John

    2011-01-01

    This paper presents IEC/SC 45B Radiation protection instrumentation and its standards for individual monitoring of ionising radiation: IEC 61526 Ed. 3 for active personal dosemeters and IEC 62387-1 for passive integrating dosimetry systems. The transposition of these standards as CENELEC (European) standards is also discussed together with the collaboration between IEC/SC 45B and ISO/TC 85/SC 2.

  14. Chemical evolution of groundwater near a sinkhole lake, northern Florida--2. Chemical patterns, mass-transfer modeling, and rates of chemical reactions

    USGS Publications Warehouse

    Katz, Brian G.; Plummer, L. Niel; Busenberg, Eurybiades; Revesz, Kinga M.; Jones, Blair F.; Lee, Terrie M.

    1995-01-01

    Chemical patterns along evolutionary groundwater flow paths in silicate and carbonate aquifers were interpreted using solute tracers, carbon and sulfur isotopes, and mass balance reaction modeling for a complex hydrologic system involving groundwater inflow to and outflow from a sinkhole lake in northern Florida. Rates of dominant reactions along defined flow paths were estimated from modeled mass transfer and ages obtained from CFC-modeled recharge dates. Groundwater upgradient from Lake Barco remains oxic as it moves downward, reacting with silicate minerals in a system open to carbon dioxide (CO2), producing only small increases in dissolved species. Beneath and downgradient of Lake Barco the oxic groundwater mixes with lake water leakage in a highly reducing, silicate-carbonate mineral environment. A mixing model, developed for anoxic groundwater downgradient from the lake, accounted for the observed chemical and isotopic composition by combining different proportions of lake water leakage and infiltrating meteoric water. The evolution of major ion chemistry and the 13C isotopic composition of dissolved carbon species in groundwater downgradient from the lake can be explained by the aerobic oxidation of organic matter in the lake, anaerobic microbial oxidation of organic carbon, and incongruent dissolution of smectite minerals to kaolinite. The dominant process for the generation of methane was by the CO2 reduction pathway based on the isotopic composition of hydrogen (δ2H(CH4) = −186 to −234‰) and carbon (δ13C(CH4) = −65.7 to −72.3‰). Rates of microbial metabolism of organic matter, estimated from the mass transfer reaction models, ranged from 0.0047 to 0.039 mmol L−1 yr−1 for groundwater downgradient from the lake.

  15. Erich Regener and the ionisation maximum of the atmosphere

    NASA Astrophysics Data System (ADS)

    Carlson, P.; Watson, A. A.

    2014-12-01

    In the 1930s the German physicist Erich Regener (1881-1955) did important work on the measurement of the rate of production of ionisation deep under water and in the atmosphere. Along with one of his students, Georg Pfotzer, he discovered the altitude at which the production of ionisation in the atmosphere reaches a maximum, often, but misleadingly, called the Pfotzer maximum. Regener was one of the first to estimate the energy density of cosmic rays, an estimate that was used by Baade and Zwicky to bolster their postulate that supernovae might be their source. Yet Regener's name is less recognised by present-day cosmic ray physicists than it should be, largely because in 1937 he was forced to take early retirement by the National Socialists as his wife had Jewish ancestors. In this paper we briefly review his work on cosmic rays and recommend an alternative naming of the ionisation maximum. The influence that Regener had on the field through his son, his son-in-law, his grandsons and his students, and through his links with Rutherford's group in Cambridge, is discussed in an appendix. Regener was nominated for the Nobel Prize in Physics by Schrödinger in 1938. He died in 1955 at the age of 73.

  16. Chemical evolution of a travertine-depositing stream: geochemical processes and mass transfer reactions

    SciTech Connect

    Lorah, M.M.; Herman, J.S.

    1988-09-01

    This field study focuses on quantitatively defining the chemical changes occurring in Falling Spring Creek, a travertine-depositing stream located in Alleghany County, Virginia. The processes of CO/sub 2/ outgassing and calcite precipitation or dissolution control the chemical evolution of the stream. The observed chemical composition of the water was used with the computerized geochemical model WATEQF to calculate aqueous speciation, saturation indices, and CO/sub 2/ partial pressure values. Mass balance calculations were performed to obtain mass transfers of CO/sub 2/ and calcite. Reaction times, estimated from stream discharge, were used with the mass transfer results to calculate rates of CO/sub 2/ outgassing and calcite precipitation between consecutive sampling points. The stream, which is fed by a carbonate spring, is supersaturated with respect to CO/sub 2/ along the entire 5.2-km flow path. Outgassing of CO/sub 2/ drives the solution to high degrees of supersaturation with respect to calcite. Metabolic uptake of CO/sub 2/ by photosynthetic plants is insignificant, because the high supply rate of dissolved carbon dioxide and the extreme agitation of the stream at waterfalls and rapids causes a much greater amount of inorganic CO/sub 2/ outgassing to occur. Calcite precipitation is kinetically inhibited until near the crest of a 20-m vertical waterfall. Calcite precipitation rates then reach a maximum at the waterfall where greater water turbulence allows the most rapid escape of CO/sub 2/. Physical evidence for calcite precipitation exists in the travertine deposits which are first observed immediately above the waterfall and extend for at least 1.0 km below the falls. Net calcite precipitation occurs at all times of the year but is greatest during low-flow conditions in the summer and early fall.

  17. Chemical analysis of bleach and hydroxide-based solutions after decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX).

    PubMed

    Hopkins, F B; Gravett, M R; Self, A J; Wang, M; Chua, Hoe-Chee; Hoe-Chee, C; Lee, H S Nancy; Sim, N Lee Hoi; Jones, J T A; Timperley, C M; Riches, J R

    2014-08-01

    Detailed chemical analysis of solutions used to decontaminate chemical warfare agents can be used to support verification and forensic attribution. Decontamination solutions are amongst the most difficult matrices for chemical analysis because of their corrosive and potentially emulsion-based nature. Consequently, there are relatively few publications that report their detailed chemical analysis. This paper describes the application of modern analytical techniques to the analysis of decontamination solutions following decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX). We confirm the formation of N,N-diisopropylformamide and N,N-diisopropylamine following decontamination of VX with hypochlorite-based solution, whereas they were not detected in extracts of hydroxide-based decontamination solutions by nuclear magnetic resonance (NMR) spectroscopy or gas chromatography-mass spectrometry. We report the electron ionisation and chemical ionisation mass spectroscopic details, retention indices, and NMR spectra of N,N-diisopropylformamide and N,N-diisopropylamine, as well as analytical methods suitable for their analysis and identification in solvent extracts and decontamination residues.

  18. The chemical composition of the low-mass Galactic globular cluster NGC 6362★

    NASA Astrophysics Data System (ADS)

    Massari, D.; Mucciarelli, A.; Dalessandro, E.; Bellazzini, M.; Cassisi, S.; Fiorentino, G.; Ibata, R. A.; Lardo, C.; Salaris, M.

    2017-03-01

    We present chemical abundances for 17 elements in a sample of 11 red giant branch stars in NGC 6362 from UVES spectra. NGC 6362 is one of the least massive globulars where multiple populations have been detected, yet its detailed chemical composition has not been investigated so far. NGC 6362 turns out to be a metal-intermediate ([Fe/H] = -1.07 ± 0.01 dex) cluster, with its α-peak and Fe-peak elements content compatible with that observed in clusters with similar metallicity. It also displays an enhancement in its s-process element abundances. Among the light elements involved in the multiple populations phenomenon, only [Na/Fe] shows star-to-star variations, while [Al/Fe] and [Mg/Fe] do not show any evidence for abundance spreads. A differential comparison with M4, a globular cluster with similar mass and metallicity, reveals that the two clusters share the same chemical composition. This finding suggests that NGC 6362 is indeed a regular cluster, formed from gas that has experienced the same chemical enrichment of other clusters with similar metallicity.

  19. Weapons of mass destruction: Overview of the CBRNEs (Chemical, Biological, Radiological, Nuclear, and Explosives).

    PubMed

    Prockop, Leon D

    2006-11-01

    The events of September 11, 2001, made citizens of the world acutely aware of disasters consequent to present-day terrorism. This is a war being waged for reasons obscure to many of its potential victims. The term "NBCs" was coined in reference to terrorist weapons of mass destruction, i.e., nuclear, biological and chemical. The currently accepted acronym is "CBRNE" which includes Chemical, Biological, Radiological, Nuclear, and Explosive weapons. Non-nuclear explosives are the most common terrorist weapon now in use. Nuclear and radiological weapons are beyond the scope of this publication, which focuses on the "CBEs", i.e. chemical, biological and explosive weapons. Although neurologists will not be the first responders to CBEs, they must know about the neurological effects in order to provide diagnosis and treatment to survivors. Neurological complications of chemical, biological and explosive weapons which have or may be used by terrorists are reviewed by international experts in this publication. Management and treatment profiles are outlined.

  20. Chemical vapor deposition of carbon nanotubes: a review on growth mechanism and mass production.

    PubMed

    Kumar, Mukul; Ando, Yoshinori

    2010-06-01

    This review article deals with the growth mechanism and mass production of carbon nanotubes (CNTs) by chemical vapor deposition (CVD). Different aspects of CNT synthesis and growth mechanism are reviewed in the light of latest progresses and understandings in the field. Materials aspects such as the roles of hydrocarbon, catalyst and catalyst support are discussed. Many new catalysts and new carbon sources are described. Growth-control aspects such as the effects of temperature, vapor pressure and catalyst concentration on CNT diameter distribution and single- or multi-wall formation are explained. Latest reports of metal-catalyst-free CNT growth are considered. The mass-production aspect is discussed from the perspective of a sustainable CNT technology. Existing problems and challenges of the process are addressed with future directions.

  1. Formation and thermodynamics of gaseous germanium and tin vanadates: a mass spectrometric and quantum chemical study.

    PubMed

    Shugurov, S M; Panin, A I; Lopatin, S I; Emelyanova, K A

    2015-06-07

    The stabilities of gaseous germanium and tin vanadates were confirmed by high temperature mass spectrometry, and its structures were determined by quantum chemical calculations. A number of gas-phase reactions involving these gaseous salts were studied. On the basis of the equilibrium constants, the standard formation enthalpies of gaseous GeV2O6 (-1520 ± 42 kJ mol(-1)) and SnV2O6 (-1520 ± 43 kJ mol(-1)) were determined at a temperature of 298 K.

  2. Ion mobility-mass spectrometry strategies for untargeted systems, synthetic, and chemical biology

    PubMed Central

    May, Jody C.; Goodwin, Cody R.; McLean, John A.

    2014-01-01

    Contemporary strategies that concentrate on only one or a handful of molecular targets limits the utility of the information gained for diagnostic and predictive purposes. Recent advances in the sensitivity, speed, and precision of measurements obtained from ion mobility coupled to mass spectrometry (IM-MS) have accelerated the utility of IM-MS in untargeted, discovery-driven studies in biology. Perhaps most evident is the impact that such wide-scale discovery capabilities have yielded in the areas of systems, synthetic, and chemical biology, where the need for comprehensive, hypothesis-driving studies from multidimensional and unbiased data is required. PMID:25462629

  3. Heat and Mass Transfer in Unsteady Rotating Fluid Flow with Binary Chemical Reaction and Activation Energy

    PubMed Central

    Awad, Faiz G.; Motsa, Sandile; Khumalo, Melusi

    2014-01-01

    In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous fluid in presence of binary chemical reaction and Arrhenius activation energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations. PMID:25250830

  4. Chemical composition and mass closure of particulate matter at six urban sites in Europe

    NASA Astrophysics Data System (ADS)

    Sillanpää, Markus; Hillamo, Risto; Saarikoski, Sanna; Frey, Anna; Pennanen, Arto; Makkonen, Ulla; Spolnik, Zoya; Van Grieken, René; Braniš, Martin; Brunekreef, Bert; Chalbot, Marie-Cecile; Kuhlbusch, Thomas; Sunyer, Jordi; Kerminen, Veli-Matti; Kulmala, Markku; Salonen, Raimo O.

    The chemical composition of fine (PM 2.5) and coarse (PM 2.5-10) particulate matter was investigated in 7-week field campaigns of contrasting air pollution at six urban background sites in Europe. The campaigns were scheduled to include seasons of local public health concern due to high particulate concentrations or findings in previously conducted epidemiological studies. The sampling campaigns were carried out as follows: Duisburg/Germany October-November 2002 (autumn), Prague/Czech Republic November 2002-January 2003 (winter), Amsterdam/Netherlands January-March 2003 (winter), Helsinki/Finland March-May 2003 (spring), Barcelona/Spain March-May 2003 (spring) and Athens/Greece June-July 2003 (summer). Aerosol samples were collected in 3+4-day periods per week ( N=14) using two identical virtual impactors (VI). All the filter samples were analysed with the same instruments to obtain particulate mass, inorganic ions, total and watersoluble elements, and elemental and organic carbon content. The campaign means of PM 2.5 and PM 2.5-10 ranged from 8.3 to 30 and 5.4 to 29 μg m -3, respectively. The "wet and cool" seasons favoured a low coarse-to-fine particulate mass ratio (<1), whereas the ratio was high (>1) during the warmer and drier spring and summer campaigns. According to chemical mass closure, the major components in PM 2.5 were carbonaceous compounds (organic matter+elemental carbon), secondary inorganic ions and sea salt, whereas those in PM 2.5-10 were soil-derived compounds, carbonaceous compounds, sea salt and nitrate. The major and minor components together accounted for 79-106% and 77-96% of the gravimetrically measured PM 2.5 and PM 2.5-10 mass, respectively. In conclusion, the measured PM 2.5 and PM 2.5-10 in the campaigns could be reconstructed to a large extent with the help of harmonized particulate sampling and analysis of the selected chemical constituents. The health significance of the observed differences in chemical composition and emission

  5. Exact masses and chemical formulas of individual Suwannee River fulvic acids from ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectra.

    PubMed

    Stenson, Alexandra C; Marshall, Alan G; Cooper, William T

    2003-03-15

    Molecular formulas have been assigned for 4626 individual Suwannee River fulvic acids based on accurate mass measurements from ions generated by electrospray ionization and observed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). Formula assignments were possible because of the mass accuracy of FTICR MS at high field (9.4 T) and the regular mass spacing patterns found in fulvic acid mixtures. Sorting the 4626 individually observed ions according to Kendrick mass defect and nominal mass series (z* score) revealed that all could be assigned to 1 of 266 distinct homologous series that differ in oxygen content and double bond equivalence. Tandem mass spectrometry based on infrared multiphoton dissociation identified labile fragments of fulvic acid molecules, whose chemical formulas led to plausible structures consistent with degraded lignin as a source of Suwannee River fulvic acids.

  6. Chemical consequences of low star formation rates: stochastically sampling the initial mass function

    NASA Astrophysics Data System (ADS)

    Carigi, L.; Hernandez, X.

    2008-10-01

    When estimating the abundances which result from a given star formation event, it is customary to treat the initial mass function (IMF) as a series of weight factors to be applied to the stellar yields, as a function of mass, implicitly assuming one is dealing with an infinite population. However, when the stellar population is small, the standard procedure would imply the inclusion of fractional numbers of stars at certain masses. We study the effects of small number statistics on the resulting abundances by performing a statistical sampling of the IMF to form a stellar population out of discrete numbers of stars. A chemical evolution code then follows the evolution of the population, and traces the resulting abundances. The process is repeated to obtain a statistical distribution of the resulting abundances and their evolution. We explore the manner in which different elements are affected, and how different abundances converge to the infinite population limit as the total mass increases. We include a discussion of our results in the context of dwarf spheroidal galaxies and show the recently reported internal dispersions in abundance ratios for dSph galaxies might be partly explained through the stochastic effects introduced by a low star formation rate, which can account for dispersions of over 2 dex in [C/O], [N/O], [C/Fe], [N/Fe] and [O/Fe].

  7. Application of a trochoidal electron monochromator/mass spectrometer system to the study of environmental chemicals

    SciTech Connect

    Laramee, J.A.; Kocher, C.A.; Deinzer, M.L. )

    1992-10-15

    A trochoidal electron monochromator has been interfaced to a mass spectrometer to perform electron capture negative ion mass spectrometric (ECNIMS) analyses of environmentally relevant chemicals. The kinetic energy of the electron beam can be varied from 0.025 to 30 eV under computer control. No reagent gas is used to moderate the electron energies. An electron energy spread of +/- 0.1 to +/- 0.4 eV full width at half-maximum (fwhm) can readily be obtained at a transmitted current of 2 x 10(-6) A, improving to +/- 0.07 eV at 5 x 10(-7) A. Comparisons of ECNI results from the electron monochromator/mass spectrometer system with those from a standard instrument that uses a moderating gas show similar spectra for heptachlor but not for the s-triazine herbicides, as for example, atrazine. This compound shows numerous adduct ions by standard ECNIMS that are eliminated by using the electron monochromator to generate the mass spectra. Isomeric tetrachlorodibenzo-p-dioxins show distinct differences in the electron energies needed to produce the maximum amount of parent and fragment anions. Multiple resonance states resulting in stable radical anions (M.-) are easily observed for nitrobenzene and for polycyclic aromatic hydrocarbons. Ionic products of dissociative electron capture invariably occur from several resonance states.

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

    PubMed

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

    1986-11-01

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

  9. Low-Cost Micro Mass Spectrometers for Handheld Chemical Analysis and Distributed Networks for Space Flight Missions

    NASA Astrophysics Data System (ADS)

    van Amerom, F. H. W.; Chaudhary, A.; Short, R. T.

    2012-06-01

    Distributed networks of low-cost micro mass spectrometers, far smaller than presently available, will be powerful tools for safety of astronauts, enabling chemical monitoring throughout spacecrafts/habitats, surface vehicles and Mars deployments.

  10. Simultaneous Determination of Cyanide and Thiocyanate in Plasma by Chemical Ionization Gas Chromatography Mass-Spectrometry (CI-GC-MS)

    DTIC Science & Technology

    2012-09-04

    ORIGINAL PAPER Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS...chemical ioniza- tion gas chromatography-mass spectrometry was developed for the simultaneous determination of cyanide and thiocya- nate in plasma...Sample preparation for this analysis required essentially one-step by combining the reaction of cyanide and thiocyanate with pentafluorobenzyl bromide

  11. Chemical composition measurements of the atmosphere of Jupiter with the Galileo Probe mass spectrometer

    NASA Technical Reports Server (NTRS)

    Niemann, H. B.; Atreya, S. K.; Carignan, G. R.; Donahue, T. M.; Haberman, J. A.; Harpold, D. N.; Hartle, R. E.; Hunten, D. M.; Kasprzak, W. T.; Mahaffy, P. R.; Owen, T. C.; Spencer, N. W.

    1998-01-01

    The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995. Measurements of the chemical and isotopic composition of the Jovian atmosphere were obtained by the mass spectrometer during the descent over the 0.5 to 21 bar pressure region over a time period of approximately 1 hour. The sampling was either of atmospheric gases directly introduced into the ion source of the mass spectrometer through capillary leaks or of gas, which had been chemically processed to enhance the sensitivity of the measurement to trace species or noble gases. The analysis of this data set continues to be refined based on supporting laboratory studies on an engineering unit. The mixing ratios of the major constituents of the atmosphere hydrogen and helium have been determined as well as mixing ratios or upper limits for several less abundant species including: methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. Analysis also suggests the presence of trace levels of other 3 and 4 carbon hydrocarbons, or carbon and nitrogen containing species, phosphine, hydrogen chloride, and of benzene. The data set also allows upper limits to be set for many species of interest which were not detected. Isotope ratios were measured for 3He/4He, D/H, 13C/12C, 20Ne/22Ne, 38Ar/36Ar and for isotopes of both Kr and Xe.

  12. Mass and energy balance constraints on the biological production of chemicals from coal

    SciTech Connect

    Andrews, G.

    1990-01-01

    Several organic chemicals, including methane and ethanol, may be produced by the bioprocessing of coal. This may be done either by direct microbial attack on the coal, or indirectly by the bioprocessing of solubilized coal. As in chemical liquefaction and gasification, the relative amounts of the various products that can be produced are severely constrained by mass and energy balance considerations. The main differences in biological processing are that water is a ubiquitous reactant, carbon dioxide a common product, and that some of the carbon and nitrogen in the coal may go to the synthesis of new biomass rather than products. The conventional biotechnological yield analysis applied to coal processing has several interesting consequences. The mass balance reduces to a balance of available electrons, and coal has a similar oxidation/reduction state to both carbohydrates and biomass. This makes high product yields feasible particularly under anaerobic conditions, although leaving open the question of whether the relevant hydrolase enzymes exist. Recommendations are made on products, and combinations of two products, that may be made with high yields and economic return. The energy balance provides little extra information. A general intracellular energy balance can be written in terms of the production and consumption of ATP, but much of the necessary information on the metabolic pathways is currently not available for coal processing microorganisms. 9 refs., 2 figs., 2 tabs.

  13. Chemical Imaging of Lipid Domains by High-Resolution Secondary Ion Mass Spectrometry

    SciTech Connect

    Kraft, M L; Weber, P K; Longo, M L; Hutcheon, I D; Boxer, S G

    2005-09-30

    Lipid microdomains within supported lipid bilayers composed of binary phosphocholine mixtures were chemically imaged by high-resolution secondary ion mass spectrometry performed with the NanoSIMS 50 (Cameca Instruments). This instrument images the sample components based on the elemental or isotopic composition of their atomic and small molecular secondary ions. Up to five different secondary ions can be simultaneously detected, and a lateral resolution of 50 nm can be achieved with high sensitivity at high mass resolution. In our experiments, the NanoSIMS 50 extensively fragmented the supported membrane, therefore an isotopic labeling strategy was used to encode the identities of the lipid components. Supported lipid membranes that contained distinct lipid microdomains were freeze-dried to preserve their lateral organization and analyzed with the NanoSIMS 50. Lipid microdomains as small as 100 nm in diameter were successfully imaged, and this was validated by comparison to AFM images taken at the same region prior to chemical imaging. Quantitative information on the lipid distribution within the domain was also determined by calibrating against supported membranes of known composition. We believe this will be a valuable approach for analyzing the composition of complex membrane domains with high spatial resolution.

  14. 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.

  15. A mass weighted chemical elastic network model elucidates closed form domain motions in proteins

    PubMed Central

    Kim, Min Hyeok; Seo, Sangjae; Jeong, Jay Il; Kim, Bum Joon; Liu, Wing Kam; Lim, Byeong Soo; Choi, Jae Boong; Kim, Moon Ki

    2013-01-01

    An elastic network model (ENM), usually Cα coarse-grained one, has been widely used to study protein dynamics as an alternative to classical molecular dynamics simulation. This simple approach dramatically saves the computational cost, but sometimes fails to describe a feasible conformational change due to unrealistically excessive spring connections. To overcome this limitation, we propose a mass-weighted chemical elastic network model (MWCENM) in which the total mass of each residue is assumed to be concentrated on the representative alpha carbon atom and various stiffness values are precisely assigned according to the types of chemical interactions. We test MWCENM on several well-known proteins of which both closed and open conformations are available as well as three α-helix rich proteins. Their normal mode analysis reveals that MWCENM not only generates more plausible conformational changes, especially for closed forms of proteins, but also preserves protein secondary structures thus distinguishing MWCENM from traditional ENMs. In addition, MWCENM also reduces computational burden by using a more sparse stiffness matrix. PMID:23456820

  16. SOURCE APPORTIONMENT OF PM 2.5 AND CARBON IN SEATTLE USING CHEMICAL MASS BALANCE AND POSITIVE MATRIX FACTORIZATION

    EPA Science Inventory

    Three years of PM2.5 speciated data were collected and chemically analyzed using the IMPROVE protocol at the Beacon Hill site in Seattle. The data were analyzed by the Chemical Mass Balance Version 8 (CMB8) and Positive Matrix Factorization (PMF) source apportionment models. T...

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

    PubMed

    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

    2016-03-27

    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.

  18. 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.

  19. 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

  20. Quantitative analysis of chemical warfare agent degradation products in beverages by liquid chromatography tandem mass spectrometry.

    PubMed

    Owens, Janel; Koester, Carolyn

    2009-09-23

    Though chemical warfare agents (CWAs) have been banned by the Chemical Weapons Convention, the threat that such chemicals may be used, including their deliberate addition to food, remains. In such matrixes, CWAs may hydrolyze to phosphonic acids, which are good surrogate markers of CWA contamination. The method described here details the extraction of five CWA degradation products, including methylphosphonic acid (MPA), ethyl-MPA, isopropyl-MPA, cyclohexyl-MPA, and pinacolyl-MPA, from five different beverages by strata-X solid phase extraction cartridges. Samples were analyzed by liquid chromatography tandem mass spectrometry (LC/MS/MS) with multiple reaction monitoring. The limit of quantitation ranged from 0.05 to 0.5 ng on-column, and the limit of detection was >0.02 ng on-column. Beverages were fortified with the five phosphonic acids at 1 microg/mL and 0.25 microg/mL and quantitated using both an internally standardized method and matrix-matched standards. Reasonable recoveries (>50%) were achieved for ethyl, isopropyl, cyclohexyl, and pinacolyl-MPA for most matrixes.

  1. Tracing origins of complex pharmaceutical preparations using surface desorption atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Zhang, Xinglei; Jia, Bin; Huang, Keke; Hu, Bin; Chen, Rong; Chen, Huanwen

    2010-10-01

    A novel strategy to trace the origins of commercial pharmaceutical products has been developed based on the direct chemical profiling of the pharmaceutical products by surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS). Besides the unambiguous identification of active drug components, various compounds present in the matrixes are simultaneously detected without sample pretreatment, providing valuable information for drug quality control and origin differentiation. Four sources of commercial amoxicillin products made by different manufacturers have been successfully differentiated. This strategy has been extended to secerning six sources of Liuwei Dihuang Teapills, which are herbal medicine preparations with extremely complex matrixes. The photolysis status of chemical drug products and the inferior natural herd medicine products prepared with different processes (e.g., extra heating) were also screened using the method reported here. The limit of detection achieved in the MS/MS experiments was estimated to be 1 ng/g for amoxicillin inside the capsule product. Our experimental data demonstrate that DAPCI-MS is a useful tool for rapid pharmaceutical analysis, showing promising perspectives for tracking the entire pharmaceutical supply chain to prevent counterfeit intrusions.

  2. In situ Analysis of Organic Compounds on Mars using Chemical Derivatization and Gas Chromatography Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Buch, A.; Cabane, M.; Coll, P.; Navarro-Gonzalez, R.; Mahaffy, P. R.

    2005-01-01

    One of the core science objectives of NASA's 2009 Mars Science Laboratory (MSL) mission is to determine the past or present habitability of Mars. The search for key organic compounds relevant to terrestrial life will be an important part of that assessment. We have developed a protocol for the analysis of amino acids and carboxylic acids in Mars analogue materials using gas chromatography mass spectrometry (GCMS). As shown, a variety of carboxylic acids were readily identified in soil collected from the Atacama Desert in Chile at part-per-billion levels by GCMS after extraction and chemical derivatization using the reagent N,N-tert.-butyl (dimethylsilyl) trifluoroacetamide (MTBSTFA). Several derivatized amino acids including glycine and alanine were also detected by GCMS in the Atacama soil at lower concentrations (chromatogram not shown). Lacking derivatization capability, the Viking pyrolysis GCMS instruments could not have detected amino acids and carboxylic acids, since these non-volatile compounds require chemical transformation into volatile species that are stable in a GC column. We are currently optimizing the chemical extraction and derivatization technique for in situ GCMS analysis on Mars. Laboratory results of analyses of Atacama Desert samples and other Mars analogue materials using this protocol will be presented.

  3. Chemical imaging of latent fingerprints by mass spectrometry based on laser activated electron tunneling.

    PubMed

    Tang, Xuemei; Huang, Lulu; Zhang, Wenyang; Zhong, Hongying

    2015-03-03

    Identification of endogenous and exogenous chemicals contained in latent fingerprints is important for forensic science in order to acquire evidence of criminal identities and contacts with specific chemicals. Mass spectrometry has emerged as a powerful technique for such applications without any derivatization or fluorescent tags. Among these techniques, MALDI (Matrix Assisted Laser Desorption Ionization) provides small beam size but has interferences with MALDI matrix materials, which cause ion suppressions as well as limited spatial resolution resulting from uneven distribution of MALDI matrix crystals with different sizes. LAET (Laser Activated Electron Tunneling) described in this work offers capabilities for chemical imaging through electron-directed soft ionization. A special film of semiconductors has been designed for collection of fingerprints. Nanoparticles of bismuth cobalt zinc oxide were compressed on a conductive metal substrate (Al or Cu sticky tape) under 10 MPa pressure. Resultant uniform thin films provide tight and shining surfaces on which fingers are impressed. Irradiation of ultraviolet laser pulses (355 nm) on the thin film instantly generates photoelectrons that can be captured by adsorbed organic molecules and subsequently cause electron-directed ionization and fragmentation. Imaging of latent fingerprints is achieved by visualization of the spatial distribution of these molecular ions and structural information-rich fragment ions. Atomic electron emission together with finely tuned laser beam size improve spatial resolution. With the LAET technique, imaging analysis not only can identify physical shapes but also reveal endogenous metabolites present in females and males, detect contacts with prohibited substances, and resolve overlapped latent fingerprints.

  4. Chemical mass balance source apportionment of PM 10 in an industrialized urban area of Northern Greece

    NASA Astrophysics Data System (ADS)

    Samara, C.; Kouimtzis, Th; Tsitouridou, R.; Kanias, G.; Simeonov, V.

    Ambient PM 10 were sampled at three sites in an industrialized urban area of Northern Greece during June 1997-June 1998 and analyzed for 17 chemical elements, 5 water-soluble ions and 13 polycyclic aromatic hydrocarbons. In addition, chemical source profiles consisting of the same particulate components were obtained for a number of industrial activities (cement, fertilizer and asphalt production, quarry operations, metal electroplating, metal welding and tempering, steel manufacture, lead and bronze smelters, metal scrap incineration), residential oil burning, non-catalyst and catalyst-equipped passenger cars, diesel fuelled taxis and buses, as well as for geological fugitive sources (paved road dust and soil from open lands). Ambient and source data were used in a chemical mass balance (CMB) receptor model for source identification and apportionment. Results of CMB modeling showed that major source of ambient PM 10 at all three sites was diesel vehicle exhaust. Significant contribution from industrial oil burning was also evidenced at the site located closest to the industrial area.

  5. Chemical crosslinking and mass spectrometry studies of the structure and dynamics of membrane proteins and receptors.

    SciTech Connect

    Haskins, William E.; Leavell, Michael D.; Lane, Pamela; Jacobsen, Richard B.; Hong, Joohee; Ayson, Marites J.; Wood, Nichole L.; Schoeniger, Joseph S.; Kruppa, Gary Hermann; Sale, Kenneth L.; Young, Malin M.; Novak, Petr

    2005-03-01

    Membrane proteins make up a diverse and important subset of proteins for which structural information is limited. In this study, chemical cross-linking and mass spectrometry were used to explore the structure of the G-protein-coupled photoreceptor bovine rhodopsin in the dark-state conformation. All experiments were performed in rod outer segment membranes using amino acid 'handles' in the native protein sequence and thus minimizing perturbations to the native protein structure. Cysteine and lysine residues were covalently cross-linked using commercially available reagents with a range of linker arm lengths. Following chemical digestion of cross-linked protein, cross-linked peptides were identified by accurate mass measurement using liquid chromatography-fourier transform mass spectrometry and an automated data analysis pipeline. Assignments were confirmed and, if necessary, resolved, by tandem MS. The relative reactivity of lysine residues participating in cross-links was evaluated by labeling with NHS-esters. A distinct pattern of cross-link formation within the C-terminal domain, and between loop I and the C-terminal domain, emerged. Theoretical distances based on cross-linking were compared to inter-atomic distances determined from the energy-minimized X-ray crystal structure and Monte Carlo conformational search procedures. In general, the observed cross-links can be explained by re-positioning participating side-chains without significantly altering backbone structure. One exception, between C3 16 and K325, requires backbone motion to bring the reactive atoms into sufficient proximity for cross-linking. Evidence from other studies suggests that residues around K325 for a region of high backbone mobility. These findings show that cross-linking studies can provide insight into the structural dynamics of membrane proteins in their native environment.

  6. Chemical composition, mass closure and sources of atmospheric PM10 from industrial sites in Shenzhen, China.

    PubMed

    Wu, Gang; Du, Xin; Wu, Xuefang; Fu, Xiao; Kong, Shaofei; Chen, Jianhua; Wang, Zongshuang; Bai, Zhipeng

    2013-08-01

    Concentrations of atmospheric PM10 and chemical components (including twenty-one elements, nine ions, organic carbon (OC) and elemental carbon (EC)) were measured at five sites in a heavily industrial region of Shenzhen, China in 2005. Results showed that PM10 concentrations exhibited the highest values at 264 microg/m3 at the site near a harbor with the influence of harbor activities. Sulfur exhibited the highest concentrations (from 2419 to 3995 ng/m3) of all the studied elements, which may be related to the influence of coal used as fuel in this area for industrial plants. This was verified by the high mass percentages of SO4(2-), which accounted for 34.3%-39.7% of the total ions. NO3-/SO4(2-) ratios varied from 0.64-0.71, which implies coal combustion was predominant compared with vehicle emission. The anion/cation ratios range was close to 0.95, indicating anion deficiency in this region. The harbor site showed the highest OC and EC concentrations, with the influence of emission from vessels. Secondary organic carbon accounted for about 22.6%-38.7% of OC, with the highest percentage occurring at the site adjacent to a coal-fired power plant and wood plant. The mass closure model performed well in this heavily industrial region, with significant correlation obtained between chemically determined and gravimetrically measured PM10 mass. The main constituents of PM10 were found to be organic materials (30.9%-69.5%), followed by secondary inorganic aerosol (7.9%-25.0%), crustal materials (6.7%-13.8%), elemental carbon (3.5%-10.8%), sea salt (2.4%-6.2%) and trace elements (2.0%-4.9%) in this heavily industrialized region. Principal component analysis indicated that the main sources for particulate matter in this industrial region were crustal materials and coal/wood combustion, oil combustion, secondary aerosols, industrial processes and vehicle emission.

  7. Mass Spectrometric Quantification of Histone Post-translational Modifications by a Hybrid Chemical Labeling Method

    PubMed Central

    Maile, Tobias M.; Izrael-Tomasevic, Anita; Cheung, Tommy; Guler, Gulfem D.; Tindell, Charles; Masselot, Alexandre; Liang, Jun; Zhao, Feng; Trojer, Patrick; Classon, Marie; Arnott, David

    2015-01-01

    Mass spectrometry is a powerful alternative to antibody-based methods for the analysis of histone post-translational modifications (marks). A key development in this approach was the deliberate propionylation of histones to improve sequence coverage across the lysine-rich and hydrophilic tails that bear most modifications. Several marks continue to be problematic however, particularly di- and tri-methylated lysine 4 of histone H3 which we found to be subject to substantial and selective losses during sample preparation and liquid chromatography-mass spectrometry. We developed a new method employing a “one-pot” hybrid chemical derivatization of histones, whereby an initial conversion of free lysines to their propionylated forms under mild aqueous conditions is followed by trypsin digestion and labeling of new peptide N termini with phenyl isocyanate. High resolution mass spectrometry was used to collect qualitative and quantitative data, and a novel web-based software application (Fishtones) was developed for viewing and quantifying histone marks in the resulting data sets. Recoveries of 53 methyl, acetyl, and phosphoryl marks on histone H3.1 were improved by an average of threefold overall, and over 50-fold for H3K4 di- and tri-methyl marks. The power of this workflow for epigenetic research and drug discovery was demonstrated by measuring quantitative changes in H3K4 trimethylation induced by small molecule inhibitors of lysine demethylases and siRNA knockdown of epigenetic modifiers ASH2L and WDR5. PMID:25680960

  8. Autonomous bio-chemical decontaminator (ABCD) against weapons of mass destruction

    NASA Astrophysics Data System (ADS)

    Hyacinthe, Berg P.

    2006-05-01

    The proliferation of weapons of mass destruction (WMD) and the use of such elements pose an eminent asymmetric threat with disastrous consequences to the national security of any nation. In particular, the use of biochemical warfare agents against civilians and unprotected troops in international conflicts or by terrorists against civilians is considered as a very peculiar threat. Accordingly, taking a quarantine-before-inhalation approach to biochemical warfare, the author introduces the notion of autonomous biochemical decontamination against WMD. In the unfortunate event of a biochemical attack, the apparatus proposed herein is intended to automatically detect, identify, and more importantly neutralize a biochemical threat. Along with warnings concerning a cyber-WMD nexus, various sections cover discussions on human senses and computer sensors, corroborating evidence related to detection and neutralization of chemical toxins, and cyber-assisted olfaction in stand alone, peer-to-peer, and network settings. In essence, the apparatus can be used in aviation and mass transit security to initiate mass decontamination by dispersing a decontaminant aerosol or to protect the public water supply against a potential bioterrorist attack. Future effort may involve a system-on-chip (SoC) embodiment of this apparatus that allows a safer environment for the emerging phenomenon of cyber-assisted olfaction and morph cell phones into ubiquitous sensors/decontaminators. Although this paper covers mechanisms and protocols to avail a neutralizing substance, further research will need to explore the substance's various pharmacological profiles and potential side effects.

  9. Mass sensitivity analysis and designing of surface acoustic wave resonators for chemical sensors

    NASA Astrophysics Data System (ADS)

    Kshetrimayum, Roshan; Yadava, R. D. S.; Tandon, R. P.

    2009-05-01

    The sensitivity of surface acoustic wave (SAW) chemical sensors depends on several factors such as the frequency and phase point of SAW device operation, sensitivity of the SAW velocity to surface mass loading, sensitivity of the SAW oscillator resonance to the loop phase shift, film thickness and oscillator electronics. This paper analyzes the influence of the phase point of operation in SAW oscillator sensors based on two-port resonator devices. It is found that the mass sensitivity will be enhanced if the SAW device has a nonlinear dependence on the frequency (delay ~ frequency-1). This requires the device to generate and operate in a ωτg(ω) = const region in the device passband, where ω denotes the angular frequency of oscillation and τg(ω) denotes the phase slope of the SAW resonator device. A SAW coupled resonator filter (CRF) that take advantage of mode coupling is considered in realizing such a device to help in shaping the phase transfer characteristics of a high mass sensitivity sensor. The device design and simulation results are presented within the coupling-of-modes formalism.

  10. In Situ Chemical Composition Measurements of Planetary Surfaces with a Laser Ablation Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Riedo, Andreas; Meyer, Stefan; Mezger, Klaus; Tulej, Marek; Wurz, Peter

    2013-04-01

    The knowledge of the chemical composition of moons, comets, asteroids or other planetary bodies is of particular importance for the investigation of the origin and evolution of the Solar System. For cosmochemistry, the elemental and isotopic composition of the surface material is essential information to investigate origin, differentiation and evolution processes of the body and therefore the history of our Solar System [1]. We show that the use of laser-based mass spectrometers is essential in such research because of their high sensitivity in the ppm range and their capability for quantitative elemental and isotopic analysis. A miniaturised Laser Ablation Time-of-Flight Mass Spectrometer (LMS) was developed in our group to study the elemental composition of solid samples [2]. The instrument's small size and light weight make it suitable for an application on a space mission to determine the elemental composition of a planetary surface for example [3]. Meteorites offer the excellent possibility to study extraterrestrial material in the laboratory. To demonstrate the sensitivity and functionality of the LMS instrument, a sample of the Allende meteorite has been investigated with a high spatial resolution. The LMS measurements allowed investigations of the elemental abundances in the Allende meteorite and detailed studies of the mineralogy and volatility [4]. These approaches can be of considerable interest for in situ investigation of grains and inhomogeneous materials with high sensitivity on a planetary surface. [1] Wurz, P., Whitby, J., Managadze, G., 2009, Laser Mass Spectrometry in Planetary Science, AIP Conf. Proc. CP1144, 70-75. [2] Tulej, M., Riedo, A., Iakovleva, M., Wurz, P., 2012, Int. J. Spec., On Applicability of a Miniaturized Laser Ablation Time of Flight Mass Spectrometer for Trace Element Measurements, article ID 234949. [3] Riedo, A., Bieler, A., Neuland, M., Tulej, M., Wurz, P., 2012, Performance evaluation of a miniature laser ablation time

  11. Ionised silica in the estuary of a river as supply to seawater: Identification and ionization efficiency of silica species by FAB-MS

    NASA Astrophysics Data System (ADS)

    Tanaka, Miho; Takahashi, Kazuya

    2013-04-01

    Measurement of the dissolution state of silicic acid is difficult. In river water, silica exists in particle form, but silica particles with a diameter of less than approximately 0.45 μm are considered as dissolved silica. In seawater, silica exists in two forms: ionic silica and particle silica. In this study, we focused on ionic silica. Using fast atom bombardment mass spectrometry (FAB-MS), the silica species in river water and seawater were detected as ionic forms. Ionic silica forms various chemical species in aquatic solutions, including the monomer ([Si]) and dimer ([Si]). The relative abundances of these species in aquatic solutions depend on the chemical and physical conditions. Silica species such as [Si(OH)2O2Na]- ([monomer-Na+]-), [Si2(OH)5O2]- ([dimer]-), [Si2(OH)4O3Na]-([dimer-Na+]-), [Si4(OH)7O5]- ([cyclic tetramer]-), [Si4(OH)6O6Na]- ([cyclic tetramer-Na+]-), [Si4(OH)9O4]- ([linear tetramer]-) and [Si4(OH)8O5Na]- ([linear tetramer-Na+]-) were directly observed by FAB-MS in river water and seawater. Some of these ionic silica species are expected to serve as "nutrients" for diatoms in seawater. Large silica particles are transported in river water, whereas in estuaries, a large amount of silica is precipitated and a small amount of silica is dissolved as ionic forms in sodium chloride solution. In river water, the concentration of silica was high, but the ionic silica species were hardly ionised by FAB-MS. In seawater, the concentration of silica was low, but the ionic silica species were well ionised. Thus, the ionization efficiency of silica species by FAB-MS indicates the type of silica species. The filtration process of silicic acid and the ionization of silicic acid to dissolve the silica species in seawater, which is an electrolyte (sodium chloride), occur in the estuary of a river. Thus, the estuary of a river plays an important role in the restructuring of silica from particle form to ionic form.

  12. Detection of Chemical/Biological Agents and Stimulants using Quadrupole Ion Trap Mass Spectrometry

    SciTech Connect

    Harmon, S.H.; Hart, K.J.; Vass, A.A.; Wise, M.B.; Wolf, D.A.

    1999-06-14

    Detection of Chemical/Biological Agents and Simulants A new detector for chemical and biological agents is being developed for the U. S. Army under the Chemical and Biological Mass Spectrometer Block II program. The CBMS Block II is designed to optimize detection of both chemical and biological agents through the use of direct sampling inlets [I], a multi- ported sampling valve and a turbo- based vacuum system to support chemical ionization. Unit mass resolution using air as the buffer gas [2] has been obtained using this design. Software to control the instrument and to analyze the data generated from the instrument has also been newly developed. Detection of chemical agents can be accomplished. using the CBMS Block II design via one of two inlets - a l/ I 6'' stainless steel sample line -Chemical Warfare Air (CW Air) or a ground probe with enclosed capillary currently in use by the US Army - CW Ground. The Block II design is capable of both electron ionization and chemical ionization. Ethanol is being used as the Cl reagent based on a study indicating best performance for the Biological Warfare (BW) detection task (31). Data showing good signal to noise for 500 pg of methyl salicylate injected into the CW Air inlet, 50 ng of dimethylmethylphosphonate exposed to the CW Ground probe and 5 ng of methyl stearate analyzed using the pyrolyzer inlet were presented. Biological agents are sampled using a ''bio-concentrator'' unit that is designed to concentrate particles in the low micron range. Particles are collected in the bottom of a quartz pyrolyzer tube. An automated injector is being developed to deliver approximately 2 pL of a methylating reagent, tetramethylamonium- hydroxide to 'the collected particles. Pyrolysis occurs by rapid heating to ca. 55OOC. Biological agents are then characterized by their fatty acid methyl ester profiles and by other biomarkers. A library of ETOH- Cl/ pyrolysis MS data of microorganisms used for a recently published study [3] has been

  13. Dilepton production as a useful probe of quark gluon plasma with temperature dependent chemical potential quark mass

    NASA Astrophysics Data System (ADS)

    Kumar, Yogesh; Singh, S. Somorendro

    2016-07-01

    We extend the previous study of dilepton production using [S. Somorendro Singh and Y. Kumar, Can. J. Phys. 92 (2014) 31] based on a simple quasiparticle model of quark-gluon plasma (QGP). In this model, finite value of quark mass uses temperature dependent chemical potential the so-called Temperature Dependent Chemical Potential Quark Mass (TDCPQM). We calculate dilepton production in the relevant range of mass region. It is observed that the production rate is marginally enhanced from the earlier work. This is due to the effect of TDCPQM and its effect is highly significant in the production of dilepton.

  14. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

    NASA Astrophysics Data System (ADS)

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-02-01

    The ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. Nb{{\\text{O}}x} thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction.

  15. Laboratory astrophysics experiments relating to ionising and weakly radiative shocks

    NASA Astrophysics Data System (ADS)

    Cross, Joseph; Foster, John; Graham, Peter; Busschaert, Clotilde; Charpentier, Nicolas; Danson, Colin; Doyle, Hugo; Drake, R. Paul; Falize, Emeric; Fyrth, Jim; Gumbrell, Edward; Koenig, Michel; Kuranz, Carolyn; Loupias, Berenice; Michaut, Claire; Patankar, Sid; Skidmore, Jonathan; Spindloe, Christopher; Tubman, Ellie; Woolsey, Nigel; Yurchak, Roman; Gregori, Gianluca

    2014-10-01

    The aim of the POLAR project is to simulate, in the laboratory, the accretion shock region of a magnetic cataclysmic variable binary star system. Scaling laws have shown that laser experiments can be related to astrophysical phenomena by matching relevant dimensionless parameters. As well as forming a reverse shock, relevant to the POLAR project, the experimental system is also likely formed of a weakly radiating shock and an ionisation front. Results from our experiment at the Orion Laser are presented here, alongside comparisons to simulation and the astrophysical case (of relevance to triggered star formation).

  16. Intercomparison of ionisation chamber measurements from (125)I seeds.

    PubMed

    Davies, J B; Enari, K F; Baldock, C

    2007-05-01

    The reference air kerma rates of a set of individual (125)I seeds were calculated from current measurements of a calibrated re-entrant ionisation chamber. Single seeds were distributed to seven Australian brachytherapy centres for the same measurement with the user's instrumentation. Results are expressed as the ratio of the reference air kerma rate measured by the Australian Nuclear Science & Technology Organisation (ANSTO) to the reference air kerma rate measured at the centre. The intercomparison ratios of all participants were within +/-5% of unity.

  17. NICIL: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library

    NASA Astrophysics Data System (ADS)

    Wurster, James

    2016-08-01

    NICIL (Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library) calculates the ionization values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. Written as a standalone Fortran90 module that can be implemented in existing codes, NICIL is fully parameterizable, allowing the user to choose which processes to include and decide the values of the free parameters. The module includes both cosmic ray and thermal ionization; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionized.

  18. Feedback regulated escape of ionising radiation from high redshift galaxies

    NASA Astrophysics Data System (ADS)

    Trebitsch, M.; Blaizot, J.

    2016-12-01

    Small galaxies are thought to provide the bulk of the radiation necessary to reionise the Universe by z ˜ 6. Their ionising efficiency is usually quantified by their escape fraction f_{esc}, but it is extremely hard to constrain from observations. With the goal of studying the physical processes that determine the values of the escape fraction, we have run a series of high resolution, cosmological, radiative hydrodynamics simulations centred on three galaxies. We find that the variability of the escape fraction follows that of the star formation rate, and that local feedback is necessary for radiation to escape.

  19. Cluster chemical ionization for improved confidence level in sample identification by gas chromatography/mass spectrometry.

    PubMed

    Fialkov, Alexander B; Amirav, Aviv

    2003-01-01

    Upon the supersonic expansion of helium mixed with vapor from an organic solvent (e.g. methanol), various clusters of the solvent with the sample molecules can be formed. As a result of 70 eV electron ionization of these clusters, cluster chemical ionization (cluster CI) mass spectra are obtained. These spectra are characterized by the combination of EI mass spectra of vibrationally cold molecules in the supersonic molecular beam (cold EI) with CI-like appearance of abundant protonated molecules, together with satellite peaks corresponding to protonated or non-protonated clusters of sample compounds with 1-3 solvent molecules. Like CI, cluster CI preferably occurs for polar compounds with high proton affinity. However, in contrast to conventional CI, for non-polar compounds or those with reduced proton affinity the cluster CI mass spectrum converges to that of cold EI. The appearance of a protonated molecule and its solvent cluster peaks, plus the lack of protonation and cluster satellites for prominent EI fragments, enable the unambiguous identification of the molecular ion. In turn, the insertion of the proper molecular ion into the NIST library search of the cold EI mass spectra eliminates those candidates with incorrect molecular mass and thus significantly increases the confidence level in sample identification. Furthermore, molecular mass identification is of prime importance for the analysis of unknown compounds that are absent in the library. Examples are given with emphasis on the cluster CI analysis of carbamate pesticides, high explosives and unknown samples, to demonstrate the usefulness of Supersonic GC/MS (GC/MS with supersonic molecular beam) in the analysis of these thermally labile compounds. Cluster CI is shown to be a practical ionization method, due to its ease-of-use and fast instrumental conversion between EI and cluster CI, which involves the opening of only one valve located at the make-up gas path. The ease-of-use of cluster CI is analogous

  20. Demonstration of real-time monitoring of a photolithographic exposure process using chemical ionization mass spectrometry

    SciTech Connect

    Mowry, C.D.

    1998-02-01

    Silicon wafers are coated with photoresist and exposed to ultraviolet (UV) light in a laboratory to simulate typical conditions expected in an actual semiconductor manufacturing process tool. Air is drawn through the exposure chamber and analyzed using chemical ionization mass spectrometry (CI/MS). Species that evaporate or outgas from the wafer are thus detected. The purpose of such analyses is to determine the potential of CI/MS as a real-time process monitoring tool. Results demonstrate that CI/MS can remotely detect the products evolved before, during, and after wafer UV exposure; and that the quantity and type of products vary with the photoresist coated on the wafer. Such monitoring could provide semiconductor manufacturers benefits in quality control and process analysis. Tool and photoresist manufacturers could also realize benefits from this measurement technique with respect to new tool, method, or photoresist development. The benefits realized can lead to improved device yields and reduced product and development costs.

  1. Chemical cross-linking and native mass spectrometry: A fruitful combination for structural biology

    PubMed Central

    Sinz, Andrea; Arlt, Christian; Chorev, Dror; Sharon, Michal

    2015-01-01

    Mass spectrometry (MS) is becoming increasingly popular in the field of structural biology for analyzing protein three-dimensional-structures and for mapping protein–protein interactions. In this review, the specific contributions of chemical crosslinking and native MS are outlined to reveal the structural features of proteins and protein assemblies. Both strategies are illustrated based on the examples of the tetrameric tumor suppressor protein p53 and multisubunit vinculin-Arp2/3 hybrid complexes. We describe the distinct advantages and limitations of each technique and highlight synergistic effects when both techniques are combined. Integrating both methods is especially useful for characterizing large protein assemblies and for capturing transient interactions. We also point out the future directions we foresee for a combination of in vivo crosslinking and native MS for structural investigation of intact protein assemblies. PMID:25970732

  2. Triage, monitoring, and treatment of mass casualty events involving chemical, biological, radiological, or nuclear agents

    PubMed Central

    Ramesh, Aruna C.; Kumar, S.

    2010-01-01

    In a mass casualty situation due to chemical, biological, radiological, or nuclear (CBRN) event, triage is absolutely required for categorizing the casualties in accordance with medical care priorities. Dealing with a CBRN event always starts at the local level. Even before the detection and analysis of agents can be undertaken, zoning, triage, decontamination, and treatment should be initiated promptly. While applying the triage system, the available medical resources and maximal utilization of medical assets should be taken into consideration by experienced triage officers who are most familiar with the natural course of the injury presented and have detailed information on medical assets. There are several triage systems that can be applied to CBRN casualties. With no one standardized system globally or nationally available, it is important for deploying a triage and decontamination system which is easy to follow and flexible to the available medical resources, casualty number, and severity of injury. PMID:21829319

  3. Effect of sample compositions on chemical analysis using matrix-assisted laser desorption ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schriemer, David; Dai, Yuqin; Li, Liang

    1996-11-01

    Matrix-assisted laser desorption ionization (MALDI) is an effective ionization technique for mass spectrometry. It take advantages of some unique properties of certain organic chemicals to provide entrapment, isolation, vaporization, and ionization of the analyte of interest. While the main application of the MALDI technique is currently in the area of biological molecule analysis, it is possible to use this technique for monitoring polymer chemistry such as degradation processes. This is potentially important for studying and developing environmentally degradable polymers. Direct analysis of the analyte in real-world samples is possible with MALDI. However, there is a significant effect of the overall composition of a sample on the detectability and performance of MALDI. Two examples are given to illustrate the positive and negative effects of buffers, salts, and additives on the MALDI sample preparation.

  4. Verification of chemical composition of commercially available propolis extracts by gas chromatography-mass spectrometry analysis.

    PubMed

    Czyżewska, Urszula; Konończuk, Joanna; Teul, Joanna; Drągowski, Paweł; Pawlak-Morka, Renata; Surażyński, Arkadiusz; Miltyk, Wojciech

    2015-05-01

    Propolis is a resin that is collected by honeybees from various plant sources. Due to its pharmacological properties, it is used in commercial production of nutritional supplements in pharmaceutical industry. In this study, gas chromatography-mass spectrometry was applied for quality control analysis of the three commercial specimens containing aqueous-alcoholic extracts of bee propolis. More than 230 constituents were detected in analyzed products, including flavonoids, chalcones, cinnamic acids and their esters, phenylpropenoid glycerides, and phenylpropenoid sesquiterpenoids. An allergenic benzyl cinnamate ester was also identified in all tested samples. This analytical method allows to evaluate biological activity and potential allergenic components of bee glue simultaneously. Studies on chemical composition of propolis samples may provide new approach to quality and safety control analysis in production of propolis supplementary specimens.

  5. Qualitative Gas Chromatography-Mass Spectrometry Analyses Using Amines as Chemical Ionization Reagent Gases

    NASA Astrophysics Data System (ADS)

    Little, James L.; Howard, Adam S.

    2013-12-01

    Ammonia is a very useful chemical ionization (CI) reagent gas for the qualitative analyses of compounds by positive ion gas chromatography-mass spectrometry (GCMS). The gas is readily available, inexpensive, and leaves no carbon contamination in the MS source. Compounds of interest to our laboratory typically yield abundant protonated or ammoniated species, which are indicative of a compound's molecular weight. Nevertheless, some labile compounds fragment extensively by substitution and elimination reactions and yield no molecular weight information. In these cases, a CI reagent gas mixture of methylamine in methane prepared dynamically was found to be very useful in obtaining molecular weight data. Likewise, deuterated ammonia and deuterated methylamine are useful CI reagent gases for determining the exchangeable protons in organic compounds. Deuterated methylamine CI reagent gas is conveniently prepared by dynamically mixing small amounts of methylamine with excess deuterated ammonia.

  6. Determination of ibogaine in plasma by gas chromatography--chemical ionization mass spectrometry.

    PubMed

    Ley, F R; Jeffcoat, A R; Thomas, B F

    1996-02-02

    Ibogaine is naturally occurring indole alkaloid that is currently being considered as a treatment medication for drug dependence. Although there have been a variety of investigations regarding the mechanisms of action and pharmacology of ibogaine, relatively little has been reported regarding quantitative methods. Because of the paucity of analytical methodologies, studies involving the pharmacokinetics and metabolism of ibogaine have also been limited. A method is described for the determination of ibogaine levels in plasma by gas chromatography -- methane chemical ionization mass spectrometry. [13C2H3]Ibogaine was synthesized and used as an internal standard to control for recovery during sample preparation. The assay requires one ml of plasma and is shown to be a selective and sensitive means of ibogaine quantitation.

  7. HPLC/atmospheric pressure chemical ionization-mass spectroscopy of eight regulated sulfonamides.

    PubMed

    Combs, M T; Ashraf-Khorassani, M; Taylor, L T

    1999-03-01

    Reversed phase high performance liquid chromatography coupled with on-line atmospheric pressure chemical ionization mass spectrometry, HPLC,APCI-MS, has been applied to a mixture of eight sulfonamides. In full scan mode, extracted ion chromatograms produced minimum detectable quantities (MDQ) of 0.8 ng on column, for six of the eight regulated sulfonamides investigated. Selected ion monitoring yielded a 50 pg MDQ for sulfamerazine, sulfadiazine and sulfamethazine, while, the other compounds presented higher values. Analysis of supercritical fluid extracts of chicken liver containing sulfadimethoxine were found to be easily detected by HPLC/APCI-MS. In extracts of chicken liver spiked with 25 microg/kg(-1) (25 ppb) of sulfadimethoxine this compound could be detected in selected ion mode, while 100 pg/microl(-1) was detectable in either full scan or single ion modes. The analysis method for extracted sulfadimethoxine also demonstrated good linearity and reproducibility in both single ion and scan mode.

  8. Water chemical ionization mass spectrometry of aldehydes, ketones esters, and carboxylic acids

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.

    1986-11-01

    Chemical ionization mass spectrometry (CI) of aliphatic and aromatic carbonyl compounds using water as the reagent gas provides intense pseudomolecular ions and class-specific fragmentation patterns that can be used to identify aliphatic aldehydes, ketones, carboxylic acids, and esters. The length of ester acyl and alkyl groups can easily be determined on the basis of loss of alcohols from the protonated parent. Water CI provides for an approximately 200:1 selectivity of carbonyl species over alkanes. No reagent ions are detected above 55 amu, allowing species as small as acetone, propanal, acetic acid, and methyl formate to be identified. When deuterate water was used as the reagent, only the carboxylic acids and ..beta..-diketones showed significant H/D exchange. The use of water CI to identify carbonyl compounds in a wastewater from the supercritical water extraction of lignite coal, in lemon oil, and in whiskey volatiles is discussed.

  9. Measurement error models in chemical mass balance analysis of air quality data

    NASA Astrophysics Data System (ADS)

    Christensen, William F.; Gunst, Richard F.

    The chemical mass balance (CMB) equations have been used to apportion observed pollutant concentrations to their various pollution sources. Typical analyses incorporate estimated pollution source profiles, estimated source profile error variances, and error variances associated with the ambient measurement process. Often the CMB model is fit to the data using an iteratively re-weighted least-squares algorithm to obtain the effective variance solution. We consider the chemical mass balance model within the framework of the statistical measurement error model (e.g., Fuller, W.A., Measurement Error Models, Wiley, NewYork, 1987), and we illustrate that the models assumed by each of the approaches to the CMB equations are in fact special cases of a general measurement error model. We compare alternative source contribution estimators with the commonly used effective variance estimator when standard assumptions are valid and when such assumptions are violated. Four approaches for source contribution estimation and inference are compared using computer simulation: weighted least squares (with standard errors adjusted for source profile error), the effective variance approach of Watson et al. (Atmos, Environ., 18, 1984, 1347), the Britt and Luecke (Technometrics, 15, 1973, 233) approach, and a method of moments approach given in Fuller (1987, p. 193). For the scenarios we consider, the simplistic weighted least-squares approach performs as well as the more widely used effective variance solution in most cases, and is slightly superior to the effective variance solution when source profile variability is large. The four estimation approaches are illustrated using real PM 2.5 data from Fresno and the conclusions drawn from the computer simulation are validated.

  10. Self-care Decontamination within a Chemical Exposure Mass-casualty Incident.

    PubMed

    Monteith, Raymond G; Pearce, Laurie D R

    2015-06-01

    Growing awareness and concern for the increasing frequency of incidents involving hazardous materials (HazMat) across a broad spectrum of contaminants from chemical, biological, radiological, and nuclear (CBRN) sources indicates a clear need to refine the capability to respond successfully to mass-casualty contamination incidents. Best results for decontamination from a chemical agent will be achieved if done within minutes following exposure, and delays in decontamination will increase the length of time a casualty is in contact with the contaminate. The findings presented in this report indicate that casualties involved in a HazMat/CBRN mass-casualty incident (MCI) in a typical community would not receive sufficient on-scene care because of operational delays that are integral to a standard HazMat/CBRN first response. This delay in response will mean that casualty care will shift away from the incident scene into already over-tasked health care facilities as casualties seek aid on their own. The self-care decontamination protocols recommended here present a viable option to ensure decontamination is completed in the field, at the incident scene, and that casualties are cared for more quickly and less traumatically than they would be otherwise. Introducing self-care decontamination procedures as a standard first response within the response community will improve the level of care significantly and provide essential, self-care decontamination to casualties. The process involves three distinct stages which should not be delayed; these are summarized by the acronym MADE: Move/Assist, Disrobe/Decontaminate, Evaluate/Evacuate.

  11. Odor and odorous chemical emissions from dairy and swine facilities: Part 5-Simultaneous chemical and sensory analysis with Gas Chromatography - Mass Spectrometry - Olfactometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Simultaneous chemical and sensory analyses using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) for air samples collected at barn exhaust fans were used for quantification and ranking of odor impact of target odorous gases. Fifteen target odorous VOCs (odorants) were selected. Air sampl...

  12. Characterization of recycled mushroom compost leachate by chemical analysis and thermogravimetry-mass spectrometry.

    PubMed

    Lyons, Gary; Kilpatrick, Mairead; Sharma, H S Shekhar; Noble, Ralph; Dobrovin-Pennington, Andreja; Hobbs, Phil; Andrews, Fiona; Carmichael, Eugene

    2008-08-13

    Recycled compost leachate (RCL or euphemistically named "goody water") can be a potent source of foul odor on mushroom substrate production sites and contributes to composting smells. A complex mixture of sulfur compounds, fatty acids, and nitrogen containing compounds is responsible for odor production. Fifty samples, collected from 14 compost production sites in Ireland and the U.K. over a 2 year period, were analyzed for chemical properties and by thermogravimetry-mass spectrometry (TG-MS) for compositional differences. Results indicated that aerated samples had lower values of electrical conductivity, redox potential, and dry matter content than nonaerated samples and that the higher thermal stability of aerated samples measured by TGA could be attributed to greater mineralization of the substrate due to aerobic processes. The lower temperatures noted for peak evolution of methane, water, and carbon dioxide from TG-MS analysis suggested that a more energetic process had occurred in aerated RCL storage facilities, producing greater decomposition of macromolecules that volatilized at lower temperatures. Chemical composition, thermal stability of the freeze-dried leachate, pyrolysis profiles, and relative amounts of pyrolysis products were all markers of as to how effective control measures could influence RCL quality.

  13. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-10-16

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance.

  14. Reduction of chemical formulas from the isotopic peak distributions of high-resolution mass spectra.

    PubMed

    Roussis, Stilianos G; Proulx, Richard

    2003-03-15

    A method has been developed for the reduction of the chemical formulas of compounds in complex mixtures from the isotopic peak distributions of high-resolution mass spectra. The method is based on the principle that the observed isotopic peak distribution of a mixture of compounds is a linear combination of the isotopic peak distributions of the individual compounds in the mixture. All possible chemical formulas that meet specific criteria (e.g., type and number of atoms in structure, limits of unsaturation, etc.) are enumerated, and theoretical isotopic peak distributions are generated for each formula. The relative amount of each formula is obtained from the accurately measured isotopic peak distribution and the calculated isotopic peak distributions of all candidate formulas. The formulas of compounds in simple spectra, where peak components are fully resolved, are rapidly determined by direct comparison of the calculated and experimental isotopic peak distributions. The singular value decomposition linear algebra method is used to determine the contributions of compounds in complex spectra containing unresolved peak components. The principles of the approach and typical application examples are presented. The method is most useful for the characterization of complex spectra containing partially resolved peaks and structures with multiisotopic elements.

  15. Identification of "Known Unknowns" Utilizing Accurate Mass Data and Chemical Abstracts Service Databases

    NASA Astrophysics Data System (ADS)

    Little, James L.; Cleven, Curtis D.; Brown, Stacy D.

    2011-02-01

    In many cases, an unknown to an investigator is actually known in the chemical literature. We refer to these types of compounds as "known unknowns." Chemical Abstracts Service (CAS) Registry is a particularly good source of these substances as it contains over 54 million entries. Accurate mass measurements can be used to query the CAS Registry by either molecular formulae or average molecular weights. Searching the database by the web-based version of SciFinder is the preferred approach when molecular formulae are available. However, if a definitive molecular formula cannot be ascertained, searching the database with STN Express by average molecular weights is a viable alternative. The results from either approach are refined by employing the number of associated references or minimal sample history as orthogonal filters. These approaches were shown to be successful in identifying "known unknowns" noted in LC-MS and even GC-MS analyses in our laboratory. In addition, they were demonstrated in the identification of a variety of compounds of interest to others.

  16. Particulate matter mass and chemical component concentrations over four Chinese cities along the western Pacific coast.

    PubMed

    Xu, Hong; Bi, Xiao-Hui; Zheng, Wei-Wei; Wu, Jian-Hui; Feng, Yin-Chang

    2015-02-01

    China has witnessed rapid economic growth in the past three decades, especially in coastal areas. Particulate matter (PM) pollution is becoming increasingly serious in China's cities along the western Pacific coast with the rapid development of China's society and economy. This study analyzed PM (PM10 and PM2.5) in terms of their mass and chemical composition in four coastal Chinese cities. The goal was to study the spatial variation and characteristics of PM pollution in sites under different levels of economic development and in diverse natural environments. A distinct trend for concentrations of PM and related chemical species was observed and increased from south to north in Haikou, Ningbo, Qingdao, and Tianjin. Secondary inorganic aerosols, crustal materials, and organic matter dominated the composition of both PM10 and PM2.5. Crustal materials were the most abundant species in the northern coastal areas because these areas have less vegetation cover and lower humidity than southern coastal areas. The presence of high SO4 (2-)/nitrate (NO3 (-)) concentrations indicated that the burning of coals gives significant contributions to PM10 and PM2.5. The differences observed in the characteristics of PM pollution in these coastal cities are probably caused by different levels of industrial and urban development.

  17. Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry.

    PubMed

    Zhu, Hongying; Zou, Guichang; Wang, Ning; Zhuang, Meihui; Xiong, Wei; Huang, Guangming

    2017-03-07

    The use of single-cell assays has emerged as a cutting-edge technique during the past decade. Although single-cell mass spectrometry (MS) has recently achieved remarkable results, deep biological insights have not yet been obtained, probably because of various technical issues, including the unavoidable use of matrices, the inability to maintain cell viability, low throughput because of sample pretreatment, and the lack of recordings of cell physiological activities from the same cell. In this study, we describe a patch clamp/MS-based platform that enables the sensitive, rapid, and in situ chemical profiling of single living neurons. This approach integrates modified patch clamp technique and modified MS measurements to directly collect and detect nanoliter-scale samples from the cytoplasm of single neurons in mice brain slices. Abundant possible cytoplasmic constituents were detected in a single neuron at a relatively fast rate, and over 50 metabolites were identified in this study. The advantages of direct, rapid, and in situ sampling and analysis enabled us to measure the biological activities of the cytoplasmic constituents in a single neuron, including comparing neuron types by cytoplasmic chemical constituents; observing changes in constituent concentrations as the physiological conditions, such as age, vary; and identifying the metabolic pathways of small molecules.

  18. Analysis of pesticide residues by fast gas chromatography in combination with negative chemical ionization mass spectrometry.

    PubMed

    Húsková, Renáta; Matisová, Eva; Hrouzková, Svetlana; Svorc, Lubomír

    2009-08-28

    A combination of fast GC with narrow-bore column and bench top quadrupole mass spectrometer (MS) detector in negative chemical ionization (NCI) mode (with methane as reagent gas) is set up and utilized for the ultratrace analysis of 25 selected pesticides. The observed pesticides, belonging to the endocrine disrupting chemicals (EDCs), were from different chemical classes. A comparative study with electron impact (EI) ionization was also carried out (both techniques in selected ion monitoring (SIM) mode). The programmed temperature vaporizer (PTV) injector in solvent vent mode and narrow-bore column (15mx0.15mm I.D.x0.15microm film of 5% diphenyl 95% dimethylsiloxane stationary phase) were used for effective and fast separation. Heptachlor (HPT) as internal standard (I.S.) was applied for the comparison of results obtained from absolute and normalized peak areas. Non-fatty food matrices were investigated. Fruit (apple - matrix-matched standards; orange, strawberry, plum - real samples) and vegetable (lettuce - real sample) extracts were prepared by a quick and effective QuEChERS sample preparation technique. Very good results were obtained for the characterization of fast GC-NCI-MS method analysing EDCs pesticides. Analyte response was linear from 0.01 to 150microgkg(-1) with the R(2) values in the range from 0.9936 to 1.0000 (calculated from absolute peak areas) and from 0.9956 to 1.0000 (calculated from peak areas normalized to HPT). Instrument limits of detection (LODs) and quantification (LOQs) were found at pgmL(-1) level and for the majority of analytes were up to three orders of magnitude lower for NCI compared to EI mode. In both ionization modes, repeatability of measurements expressed as relative standard deviation (RSDs) was less than 10% which is in very good agreement with the criterion of European Union.

  19. Strategies for the chemical analysis of highly porous bone scaffolds using secondary ion mass spectrometry.

    PubMed

    Wang, Daming; Poologasundarampillai, Gowsihan; van den Bergh, Wouter; Chater, Richard J; Kasuga, Toshihiro; Jones, Julian R; McPhail, David S

    2014-02-01

    Understanding the distribution of critical elements (e.g. silicon and calcium) within silica-based bone scaffolds synthesized by different methods is central to the optimization of these materials. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to determine this information due to its very high surface sensitivity and its ability to map all the elements and compounds in the periodic table with high spatial resolution. The SIMS image data can also be combined with depth profiles to construct three-dimensional chemical maps. However, the scaffolds have interconnected pore networks, which are very challenging structures for the SIMS technique. To overcome this problem two experimental methodologies have been developed. The first method involved the use of the focused ion beam technique to obtain clear images of the regions of interest and subsequently mark them by introducing fiducial marks; the samples were then analysed using the ToF-SIMS technique to yield the chemical analyses of the regions of interest. The second method involved impregnating the pores using a suitable reagent so that a flat surface could be achieved, and this was followed by secondary ion mapping and 3D chemical imaging with ToF-SIMS. The samples used in this work were sol-gel 70S30C foam and electrospun fibres and calcium-containing silica/gelatin hybrid scaffolds. The results demonstrate the feasibility of both these experimental methodologies and indicate that these methods can provide an opportunity to compare various artificial bone scaffolds, which will be of help in improving scaffold synthesis and processing routes. The techniques are also transferable to many other types of porous material.

  20. Chemical extraction versus direct smear for MALDI-TOF mass spectrometry identification of anaerobic bacteria.

    PubMed

    Fournier, Rémi; Wallet, Frédéric; Grandbastien, Bruno; Dubreuil, Luc; Courcol, René; Neut, Christel; Dessein, Rodrigue

    2012-06-01

    In the present study, two pre-analytic processes for mass spectrometric bacterial identification were compared: the time-consuming reference method, chemical extraction, and the direct smear technique directly using cultured colonies without any further preparation. These pre-analytic processes were compared in the identification of a total of 238 strains of anaerobic bacteria representing 34 species. The results showed that 218/238 strains were identified following chemical extraction, 185 identifications (77.7%) were secured to both genus and species [log(score) > 2.0] whereas 33 identifications (14%) were secured to genus only [log(score) between 1.7 and 2.0]. Following direct smear, 207/238 anaerobic bacteria were identified, 158 identifications (66.4%) were secured to both genus and species [log(score) > 2.0] whereas 49 identifications were secured to genus only [log(score) between 1.7 and 2.0]. Twenty strains were not identified [log(score) < 1.7] by MALDI-TOF MS following chemical extraction whereas 31 strains were not identified with the direct smear technique. Although direct smear led to a significant decrease of the log(score) values for the Clostridium genus and the Gram positive anaerobic bacteria (GPAC) group (p < 0.0001, Wilcoxon test), identification to both species and genus were not changed. However these differences were not statistically significant (p = 0.1, Chi square). Therefore, MALDI-TOF MS identification following the direct smear technique appears to both non-inferior to the reference method and relevant for anaerobic bacteria identification.

  1. Categorizing Cells on the Basis of their Chemical Profiles: Progress in Single-Cell Mass Spectrometry

    PubMed Central

    2017-01-01

    The chemical differences between individual cells within large cellular populations provide unique information on organisms’ homeostasis and the development of diseased states. Even genetically identical cell lineages diverge due to local microenvironments and stochastic processes. The minute sample volumes and low abundance of some constituents in cells hinder our understanding of cellular heterogeneity. Although amplification methods facilitate single-cell genomics and transcriptomics, the characterization of metabolites and proteins remains challenging both because of the lack of effective amplification approaches and the wide diversity in cellular constituents. Mass spectrometry has become an enabling technology for the investigation of individual cellular metabolite profiles with its exquisite sensitivity, large dynamic range, and ability to characterize hundreds to thousands of compounds. While advances in instrumentation have improved figures of merit, acquiring measurements at high throughput and sampling from large populations of cells are still not routine. In this Perspective, we highlight the current trends and progress in mass-spectrometry-based analysis of single cells, with a focus on the technologies that will enable the next generation of single-cell measurements. PMID:28135079

  2. Precursor ion scan profiles of acylcarnitines by atmospheric pressure thermal desorption chemical ionization tandem mass spectrometry.

    PubMed

    Paglia, Giuseppe; D'Apolito, Oceania; Corso, Gaetano

    2008-12-01

    The fatty acyl esters of L-carnitine (acylcarnitines) are useful biomarkers for the diagnosis of some inborn errors of metabolism analyzed by liquid chromatography/tandem mass spectrometry. In this study the acylcarnitines were analyzed by atmospheric pressure thermal desorption chemical ionization using a commercial tandem mass spectrometer (APTDCI-MS/MS). The method is based on the precursor ion scan mode determination of underivatized acylcarnitines desorbed from samples by a hot desolvation gas flow and ionized by a corona pin discharge. During desorption/ionization step the temperature induces the degradation of acylcarnitines; nevertheless, the common fragment to all acylcarnitines [MH-59](+) is useful for analyzing their profile. APTDCI parameters, including angle of collection and incidence, gas flows and temperatures, were optimized for acylcarnitines. The experiments were performed drying 2 microL of an equimolar mixture of acylcarnitine standards on a glass slide. The specificity was evaluated by comparing product ion spectra and the precursor ion spectra of 85 m/z of acylcarnitines obtained by the APTDCI method and by electrospray ionization flow injection analysis (ESI-FIA). The method was also employed to analyze acylcarnitines extracted from a pathological dried blood spot and a control. The method enables analysis of biological samples and recognition of some acylcarnitines that are diagnostic markers of inherited metabolic diseases. The intrinsic high-throughput analysis of the ambient desorption ionization methods offers a new opportunity either for its potential application in clinical chemistry and for the expanded screening of some inborn errors of metabolism.

  3. Quantitative Metabolome Analysis Based on Chromatographic Peak Reconstruction in Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry.

    PubMed

    Huan, Tao; Li, Liang

    2015-07-21

    Generating precise and accurate quantitative information on metabolomic changes in comparative samples is important for metabolomics research where technical variations in the metabolomic data should be minimized in order to reveal biological changes. We report a method and software program, IsoMS-Quant, for extracting quantitative information from a metabolomic data set generated by chemical isotope labeling (CIL) liquid chromatography mass spectrometry (LC-MS). Unlike previous work of relying on mass spectral peak ratio of the highest intensity peak pair to measure relative quantity difference of a differentially labeled metabolite, this new program reconstructs the chromatographic peaks of the light- and heavy-labeled metabolite pair and then calculates the ratio of their peak areas to represent the relative concentration difference in two comparative samples. Using chromatographic peaks to perform relative quantification is shown to be more precise and accurate. IsoMS-Quant is integrated with IsoMS for picking peak pairs and Zero-fill for retrieving missing peak pairs in the initial peak pairs table generated by IsoMS to form a complete tool for processing CIL LC-MS data. This program can be freely downloaded from the www.MyCompoundID.org web site for noncommercial use.

  4. Heat and mass transfer from a baby manikin: impact of a chemical warfare protective bag.

    PubMed

    Danielsson, Ulf

    2004-09-01

    A chemical warfare (CW) protective bag for babies, younger than 1 year, has been evaluated in respect of thermal load. Heat and water vapour dissipating from the baby make the climate in the protective bag more demanding than outside. The thermal strain on a baby was estimated from heat and mass transfer data using an electrically heated baby manikin and a water-filled tray. Furthermore, a theoretical baby model was developed based on relations valid for heat and mass transfer rates from a cylinder and flat surface. Convective and radiative (dry) and evaporative heat transfer coefficients calculated from this model agreed well with the measured values. The maximum heat dissipation from a baby was calculated for combinations of air temperatures (22-30 degrees C) and relative humidities (70-90% rh). The results indicate that a naked baby can dissipate about 100% more heat than is produced during basal conditions when the bag is ventilated (70 1 min(-1)) and the ambient climate is 30 degrees C and 90% rh. If the ventilation rate is 40 1 min(-1), the margin is reduced to 50%. Clothing reduces the margin further. Ventilating the bag with 70 1 min(-1), a dressed baby can dissipate only 10-20% more heat than is produced during basal conditions in a climate (27 degrees C and 80% rh) that is obtained in a crowded shelter after about 24 h of occupation.

  5. Chemical and Isotopic Thresholds in Charring: Implications for the Interpretation of Charcoal Mass and Isotopic Data.

    PubMed

    Pyle, Lacey A; Hockaday, William C; Boutton, Thomas; Zygourakis, Kyriacos; Kinney, Timothy J; Masiello, Caroline A

    2015-12-15

    Charcoal plays a significant role in the long-term carbon cycle, and its use as a soil amendment is promoted as a C sequestration strategy (biochar). One challenge in this research area is understanding the heterogeneity of charcoal properties. Although the maximum reaction temperature is often used as a gauge of pyrolysis conditions, pyrolysis duration also changes charcoal physicochemical qualities. Here, we introduce a formal definition of charring intensity (CI) to more accurately characterize pyrolysis, and we document variation in charcoal chemical properties with variation in CI. We find two types of responses to CI: either linear or threshold relationships. Mass yield decreases linearly with CI, while a threshold exists across which % C, % N, and δ(15)N exhibit large changes. This CI threshold co-occurs with an increase in charcoal aromaticity. C isotopes do not change from original biomass values, supporting the use of charcoal δ(13)C signatures to infer paleoecological conditions. Fractionation of N isotopes indicates that fire may be enriching soils in (15)N through pyrolytic N isotope fractionation. This influx of "black N" could have a significant impact on soil N isotopes, which we show theoretically using a simple mass-balance model.

  6. Mass analysis of trifluoro-iodo-methane in a Surface Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Rees, J. A.; Greenwood, C. L.; Lundie, D. T.; Seymour, D. L.; Hiden Analytical Team

    2011-10-01

    Surface barrier discharges operated at atmospheric pressure are effective chemical reactors. Mass analysis of the reaction products is possible using suitable high pressure mass spectrometer systems. As an example of the behaviour of simple surface barrier reactor (SBDs), experiments on the decomposition of CF3I are described in which the output from the reactor is admitted via a capillary inlet system into a Hiden HPR20 mass spectrometer. The discharge was operated using helium as the carrier gas. The observed mass spectra are discussed in terms of the plasma dissociation and the subsequent ionisation of the dissociated products in the electron impact ionisation source of the mass spectrometer. When oxygen was added to the gas mixture in the SBD, CFxO species were generated in the plasma. Their influence on the observed mass spectra is shown. The results demonstrate aspects of the capabilities of SBDs for dissociating halocarbon gases at atmospheric pressure and the possibilities of direct mass spectrometric monitoring of such processes.

  7. Kr-81m calibration factor for the npl ionisation chamber.

    PubMed

    Johansson, Lena; Stroak, Andrew

    2006-01-01

    A general method has been developed for the measurement of the activity concentration of 81mKr gas. Due to its short half-life, 13.1s, this gas has to be eluted from a 81Rb/81mKr generator. The 81Rb parent has a half-life of about 4.6 h. The calibration was done in two steps: firstly, a gamma-ray spectrometer was calibrated using 51Cr and 139Ce sources, nuclides with gamma-ray energies bracketing that of 81mKr (190.5 keV). The measurement geometry was equivalent to that of the 81mKr measurement; the sources were inserted into two collimated PTFE tubes in front of the gamma-ray detector. Secondly, a calibration factor for the NPL radionuclide calibrator was determined with a specially designed ionisation chamber insert. The 81mKr gas passed in front of the gamma-ray detector in PTFE tubing before and after entering the ionisation chamber. The calibration factor for 81mKr in the radionuclide calibrator with this geometry was independent of the gas flow rate within determined limits. The analytical calculations of the activity determination, uncertainties and measurement criteria are discussed.

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

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Cruikshank, D. P.

    2012-10-01

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

  9. Quantitative analysis of chemical warfare agent degradation products in reaction masses using capillary electrophoresis.

    PubMed

    Nassar, A E; Lucas, S V; Myler, C A; Jones, W R; Campisano, M; Hoffland, L D

    1998-09-01

    Quantitative methods have been developed for the analysis of chemical warfare agent degradation products in reaction masses using capillary electrophoresis (CE). This is the first report of a systematic validation of a CE-based method for the analysis of chemical warfare agent degradation products in agent neutralization matrixes (reaction masses). After neutralization with monoethanolamine/water, the nerve agent GB (isopropyl methylphosphonofluoridate, Sarin) gives isopropyl methylphosphonic acid (IMPA) and O-isopropyl O'-(2-amino)ethyl methylphosphonate (GB-MEA adduct). The nerve agent GD (pinacolyl methylphosphonofluoridate, Soman), [pinacolyl = 2-(3,3-dimethyl)butyl] produces pinacolyl methylphosphonic acid (PMPA) and O-pinacolyl O'-(2-amino)ethyl methylphosphonate (GD-MEA adduct). The samples were prepared by dilution of the reaction masses with deionized water before analysis by CE/indirect UV detection or CE/conductivity detection. Migration time precision was less than 4.0% RSD for IMPA and 5.0 RSD for PMPA on a day-to-day basis. The detection limit for both IMPA and PMPA is 100 micrograms/L; the quantitation limit for both is 500 micrograms/L. For calibration standards, IMPA and PMPA gave a linear response (R2 = 0.9999) over the range 0.5-100 micrograms/mL. The interday precision RSDs were 1.9, 1.0, and 0.7% for IMPA at 7.5, 37.5 and 75.0 micrograms/mL, respectively. Corresponding values for PMPA (again, RSD) were 2.9, 1.1, and 1.0% at 7.5, 37.5 and 87.5 micrograms/mL, respectively, as before. Analysis accuracy was assessed by spiking actual neutralization samples with IMPA or PMPA. For IMPA, the seven spike levels used ranged from 20 to 220% of the IMPA background level, and the incremental change in the found IMPA level ranged from 86 to 99 % of the true spiking increment (R2 = 0.9987 for the linear regression). For PMPA, the five spike levels ranged from 10 to 150% of the matrix background level, and similarly, the accuracy obtained ranged from 95 to 97

  10. Sensitivity of a Chemical Mass Balance model to different molecular marker traffic source profiles

    NASA Astrophysics Data System (ADS)

    Pant, Pallavi; Yin, Jianxin; Harrison, Roy M.

    2014-01-01

    Use of the Chemical Mass Balance (CMB) model for aerosol source apportionment requires the input of source profiles of chemical constituents. Such profiles derived from studies in North America are relatively abundant, but are very scarce from European studies. In particular, there is a lack of data from European road vehicles. This study reports results from a comparison of road traffic source profiles derived from (1) US dynamometer studies of individual vehicles with (2) a traffic profile derived from measurements in a road tunnel in France and (3) new data derived from a twin-site study in London in which concentrations at an urban background site are subtracted from those measured at a busy roadside to derive a traffic increment profile. The dynamometer data are input as a diesel exhaust, gasoline exhaust and smoking engine profile, or alternatively as just a diesel exhaust and gasoline exhaust profile. Running the CMB model with the various traffic profiles together with profiles for other sources of organic carbon gives variable estimates of the contribution of traffic to organic carbon and to PM2.5 concentrations. These are tested in two ways. Firstly, unassigned organic carbon in the output from the CMB model, assumed to be secondary organic carbon, is compared to secondary organic carbon estimated independently using the elemental carbon tracer method. Secondly, the estimated traffic contribution to organic carbon and PM2.5 is compared with an estimate derived simply from the measured elemental carbon concentrations, and the effect on aerosol mass closure is investigated. In both cases the CMB model results correlate well with the independent measures, but there are marked differences according to the traffic source profile employed. As a general observation, it appears that the use of dynamometer data with inclusion of a smoking engine profile has a tendency to over-estimate traffic emissions at some sites whereas the tunnel profile shows a tendency to

  11. Environmental toxicological fate prediction of diverse organic chemicals based on steady-state compartmental chemical mass ratio using quantitative structure-fate relationship (QSFR) models.

    PubMed

    Pramanik, Subrata; Roy, Kunal

    2013-07-01

    Four quantitative prediction models for steady-state compartmental chemical mass concentrations (Wn,g) were obtained from structural information, physiochemical properties, degradation rate and transport coefficients of 455 diverse organic chemicals using chemometric tools in a quantitative structure-fate relationship (QSFR) study. The mass ratio assessment of environmentally prevalent organic chemicals may be helpful to predict their toxicological fate in the ecosystems. Four sets of mass ratios [(1) log(Wair) from water emissions (water to air compartment), (2) log(Wair) from air emissions (within different zones of the air compartment), (3) log(Wwater) from water emissions (within different zones of the water compartment) and (4) log(Wwater) from air emissions (air to water compartment)] have been used. The developed models using genetic function approximation followed by multiple linear regression (GFA-MLR) and subsequent partial least squares (PLS) treatment identify only four descriptors for log(Wair) from water emission, six descriptors for log(Wair) from air emission, five descriptors for log(Wwater) from water emission and seven descriptors for log(Wwater) from air emission for predicting efficiently a large number of test set chemicals (ntest=182). The conclusive models suggest that descriptors such as partition coefficients (Kaw, Kow and Ksw), degradation parameters (Ksoil,Kwater and Kair), vapor pressure (Pv), diffusivity (Dwater), spatial descriptors (Jurs-WNSA-1, Jurs-WNSA-2, Jurs-WPSA-3, Jurs-FNSA-3 and Density), thermodynamic descriptors (MolRef and AlogP98), electrotopological state indices (S_dsN, S_ssNH and S_dsCH) are important for predicting the chemical mass ratios. The developed models may be applicable in toxicological fate prediction of diverse chemicals in the ecosystems.

  12. Mass production of chemicals from biomass-derived oil by directly atmospheric distillation coupled with co-pyrolysis

    PubMed Central

    Zhang, Xue-Song; Yang, Guang-Xi; Jiang, Hong; Liu, Wu-Jun; Ding, Hong-Sheng

    2013-01-01

    Production of renewable commodity chemicals from bio-oil derived from fast pyrolysis of biomass has received considerable interests, but hindered by the presence of innumerable components in bio-oil. In present work, we proposed and experimentally demonstrated an innovative approach combining atmospheric distillation of bio-oil with co-pyrolysis for mass production of renewable chemicals from biomass, in which no waste was produced. It was estimated that 51.86 wt.% of distillate just containing dozens of separable organic components could be recovered using this approach. Ten protogenetic and three epigenetic compounds in distillate were qualitatively identified by gas chromatography/mass spectrometry and quantified by gas chromatography. Among them, the recovery efficiencies of acetic acid, propanoic acid, and furfural were all higher than 80 wt.%. Formation pathways of the distillate components in this process were explored. This work opens up a fascinating prospect for mass production of chemical feedstock from waste biomass. PMID:23350028

  13. Mass production of chemicals from biomass-derived oil by directly atmospheric distillation coupled with co-pyrolysis

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-Song; Yang, Guang-Xi; Jiang, Hong; Liu, Wu-Jun; Ding, Hong-Sheng

    2013-01-01

    Production of renewable commodity chemicals from bio-oil derived from fast pyrolysis of biomass has received considerable interests, but hindered by the presence of innumerable components in bio-oil. In present work, we proposed and experimentally demonstrated an innovative approach combining atmospheric distillation of bio-oil with co-pyrolysis for mass production of renewable chemicals from biomass, in which no waste was produced. It was estimated that 51.86 wt.% of distillate just containing dozens of separable organic components could be recovered using this approach. Ten protogenetic and three epigenetic compounds in distillate were qualitatively identified by gas chromatography/mass spectrometry and quantified by gas chromatography. Among them, the recovery efficiencies of acetic acid, propanoic acid, and furfural were all higher than 80 wt.%. Formation pathways of the distillate components in this process were explored. This work opens up a fascinating prospect for mass production of chemical feedstock from waste biomass.

  14. The universal relation of galactic chemical evolution: the origin of the mass-metallicity relation

    SciTech Connect

    Zahid, H. Jabran; Dima, Gabriel I.; Kudritzki, Rolf-Peter; Kewley, Lisa J.; Geller, Margaret J.; Hwang, Ho Seong; Silverman, John D.; Kashino, Daichi

    2014-08-20

    We examine the mass-metallicity relation for z ≲ 1.6. The mass-metallicity relation follows a steep slope with a turnover, or 'knee', at stellar masses around 10{sup 10} M {sub ☉}. At stellar masses higher than the characteristic turnover mass, the mass-metallicity relation flattens as metallicities begin to saturate. We show that the redshift evolution of the mass-metallicity relation depends only on the evolution of the characteristic turnover mass. The relationship between metallicity and the stellar mass normalized to the characteristic turnover mass is independent of redshift. We find that the redshift-independent slope of the mass-metallicity relation is set by the slope of the relationship between gas mass and stellar mass. The turnover in the mass-metallicity relation occurs when the gas-phase oxygen abundance is high enough that the amount of oxygen locked up in low-mass stars is an appreciable fraction of the amount of oxygen produced by massive stars. The characteristic turnover mass is the stellar mass, where the stellar-to-gas mass ratio is unity. Numerical modeling suggests that the relationship between metallicity and the stellar-to-gas mass ratio is a redshift-independent, universal relationship followed by all galaxies as they evolve. The mass-metallicity relation originates from this more fundamental universal relationship between metallicity and the stellar-to-gas mass ratio. We test the validity of this universal metallicity relation in local galaxies where stellar mass, metallicity, and gas mass measurements are available. The data are consistent with a universal metallicity relation. We derive an equation for estimating the hydrogen gas mass from measurements of stellar mass and metallicity valid for z ≲ 1.6 and predict the cosmological evolution of galactic gas masses.

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

    NASA Astrophysics Data System (ADS)

    Brophy, Patrick; Farmer, Delphine K.

    2016-08-01

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

  16. Chemical analysis of diesel engine nanoparticles using a nano-DMA/thermal desorption particle beam mass spectrometer.

    PubMed

    Tobias, H J; Beving, D E; Ziemann, P J; Sakurai, H; Zuk, M; McMurry, P H; Zarling, D; Waytulonis, R; Kittelson, D B

    2001-06-01

    Diesel engines are known to emit high number concentrations of nanoparticles (diameter < 50 nm), but the physical and chemical mechanisms by which they form are not understood. Information on chemical composition is lacking because the small size, low mass concentration, and potential for contamination of samples obtained by standard techniques make nanoparticles difficult to analyze. A nano-differential mobility analyzer was used to size-select nanoparticles (mass median diameter approximately 25-60 nm) from diesel engine exhaust for subsequent chemical analysis by thermal desorption particle beam mass spectrometry. Mass spectra were used to identify and quantify nanoparticle components, and compound molecular weights and vapor pressures were estimated from calibrated desorption temperatures. Branched alkanes and alkyl-substituted cycloalkanes from unburned fuel and/or lubricating oil appear to contribute most of the diesel nanoparticle mass. The volatility of the organic fraction of the aerosol increases as the engine load decreases and as particle size increases. Sulfuric acid was also detected at estimated concentrations of a few percent of the total nanoparticle mass. The results are consistent with a mechanism of nanoparticle formation involving nucleation of sulfuric acid and water, followed by particle growth by condensation of organic species.

  17. Chemical reactions induced by high-velocity molecular impacts: challenges for closed-source mass spectrometry

    NASA Astrophysics Data System (ADS)

    Austin, Daniel

    2016-07-01

    Analysis of upper atmosphere composition using closed-source neutral mass spectrometers (e.g., Cassini INMS, MAVEN NGIMS) is subject to error due to chemical reactions caused by the high-velocity impacts of neutral molecules on the source surfaces. In addition to species traditionally considered "surface reactive" (e.g., O, N) it is likely that many or all impacting molecules are vibrationally excited to the point that chemical changes can occur. Dissociation, fragmentation, formation of radicals and ions, and other reactions likely obscure analysis of the native atmospheric composition, particularly of organic compounds. Existing techniques are not capable of recreating the relevant impact chemistry in the lab. We report on the development of a new capability allowing reactions of high-velocity neutrals impacting surfaces to be characterized directly. Molecules introduced into a vacuum chamber are impacted at several km/s by the surface of a high-speed rotor. These molecules subsequently impact multiple times on other surfaces within the vacuum chamber until they are thermalized, after which they are cryogenically collected and analyzed. Reaction pathways and thermodynamics for volatile compounds are then determined. We will present current results on this project, including data from low- and mid-range velocity experiments. This type of information is critical to clarify prior flight results and plan for future missions. Finally, we present a new type of inlet intended to significantly reduce fragmentation for impact velocities typical of a fly-by mission. Theoretical analysis indicates that this new inlet may reduce fragmentation by more than an order of magnitude for any encounter velocity.

  18. Nitrogen losses from dairy manure estimated through nitrogen mass balance and chemical markers

    USGS Publications Warehouse

    Hristov, Alexander N.; Zaman, S.; Vander Pol, M.; Ndegwa, P.; Campbell, L.; Silva, S.

    2009-01-01

    Ammonia is an important air and water pollutant, but the spatial variation in its concentrations presents technical difficulties in accurate determination of ammonia emissions from animal feeding operations. The objectives of this study were to investigate the relationship between ammonia volatilization and ??15N of dairy manure and the feasibility of estimating ammonia losses from a dairy facility using chemical markers. In Exp. 1, the N/P ratio in manure decreased by 30% in 14 d as cumulative ammonia losses increased exponentially. Delta 15N of manure increased throughout the course of the experiment and ??15N of emitted ammonia increased (p < 0.001) quadratically from -31??? to -15 ???. The relationship between cumulative ammonia losses and ??15N of manure was highly significant (p < 0.001; r2 = 0.76). In Exp. 2, using a mass balance approach, approximately half of the N excreted by dairy cows (Bos taurus) could not be accounted for in 24 h. Using N/P and N/K ratios in fresh and 24-h manure, an estimated 0.55 and 0.34 (respectively) of the N excreted with feces and urine could not be accounted for. This study demonstrated that chemical markers (P, K) can be successfully used to estimate ammonia losses from cattle manure. The relationship between manure ??15N and cumulative ammonia loss may also be useful for estimating ammonia losses. Although promising, the latter approach needs to be further studied and verified in various experimental conditions and in the field. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  19. Mass

    SciTech Connect

    Quigg, Chris

    2007-12-05

    In the classical physics we inherited from Isaac Newton, mass does not arise, it simply is. The mass of a classical object is the sum of the masses of its parts. Albert Einstein showed that the mass of a body is a measure of its energy content, inviting us to consider the origins of mass. The protons we accelerate at Fermilab are prime examples of Einsteinian matter: nearly all of their mass arises from stored energy. Missing mass led to the discovery of the noble gases, and a new form of missing mass leads us to the notion of dark matter. Starting with a brief guided tour of the meanings of mass, the colloquium will explore the multiple origins of mass. We will see how far we have come toward understanding mass, and survey the issues that guide our research today.

  20. Chemical Evolution in High-mass Star-forming Regions: Results from the MALT90 Survey

    NASA Astrophysics Data System (ADS)

    Hoq, Sadia; Jackson, James M.; Foster, Jonathan B.; Sanhueza, Patricio; Guzmán, Andrés; Whitaker, J. Scott; Claysmith, Christopher; Rathborne, Jill M.; Vasyunina, Tatiana; Vasyunin, Anton

    2013-11-01

    The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense molecular clumps associated with high-mass star formation. We use the molecular line maps from Year 1 of the Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey. The survey mapped several hundred individual star-forming clumps chosen from the ATLASGAL survey to span the complete range of evolution, from prestellar to protostellar to H II regions. The evolutionary stage of each clump is classified using the Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine the dust temperatures and H2 column densities for each clump from Herschel/Hi-GAL continuum data. From MALT90 data, we measure the integrated intensities of the N2H+, HCO+, HCN and HNC (1-0) lines, and derive the column densities and abundances of N2H+ and HCO+. The Herschel dust temperatures increase as a function of the IR-based Spitzer evolutionary classification scheme, with the youngest clumps being the coldest, which gives confidence that this classification method provides a reliable way to assign evolutionary stages to clumps. Both N2H+ and HCO+ abundances increase as a function of evolutionary stage, whereas the N2H+ (1-0) to HCO+ (1-0) integrated intensity ratios show no discernable trend. The HCN (1-0) to HNC(1-0) integrated intensity ratios show marginal evidence of an increase as the clumps evolve.

  1. Masses and age of the chemically peculiar double-lined binary χ Lupi

    NASA Astrophysics Data System (ADS)

    Le Bouquin, J.-B.; Beust, H.; Duvert, G.; Berger, J. P.; Ménard, F.; Zins, G.

    2013-03-01

    Aims: We aim at measuring the stellar parameters of the two chemically peculiar components of the B9.5Vp HgMn + A2 Vm double-lined spectroscopic binary HD 141556 (χ Lup), whose period is 15.25 days. Methods: We combined historical radial velocity measurements with new spatially resolved astrometric observations from PIONIER/VLTI to reconstruct the three-dimensional orbit of the binary, and thus obtained the individual masses. We fit the available photometric points together with the flux ratios provided by interferometry to constrain the individual sizes, which we compared to predictions from evolutionary models. Results: The individual masses of the components are Ma = 2.84 ± 0.12 M⊙ and Mb = 1.94 ± 0.09 M⊙. The dynamical distance is compatible with the Hipparcos parallax. We find linear stellar radii of Ra = 2.85 ± 0.15 R⊙ and Rb = 1.75 ± 0.18 R⊙. This result validates a posteriori the flux ratio used in previous detailed abundance studies. Assuming coevality, we determine a slightly sub-solar initial metallicity Z = 0.012 ± 0.003 and an age of (2.8 ± 0.3) × 108 years. Finally, our results imply that the primary rotates more slowly than its synchronous velocity, while the secondary is probably synchronous. We show that strong tidal coupling during the pre-main sequence evolution followed by a full decoupling at zero-age main sequence provides a plausible explanation for these very low rotation rates. Based on data collected with the PIONIER visitor-instrument installed at the ESO Paranal Observatory under program 088.D-0828.Appendices are available in electronic form at http://www.aanda.org

  2. Chemical characterization of freshly emitted particulate matter from aircraft exhaust using single particle mass spectrometry

    NASA Astrophysics Data System (ADS)

    Abegglen, Manuel; Brem, B. T.; Ellenrieder, M.; Durdina, L.; Rindlisbacher, T.; Wang, J.; Lohmann, U.; Sierau, B.

    2016-06-01

    Non-volatile aircraft engine emissions are an important anthropogenic source of soot particles in the upper troposphere and in the vicinity of airports. They influence climate and contribute to global warming. In addition, they impact air quality and thus human health and the environment. The chemical composition of non-volatile particulate matter emission from aircraft engines was investigated using single particle time-of-flight mass spectrometry. The exhaust from three different aircraft engines was sampled and analyzed. The soot particulate matter was sampled directly behind the turbine in a test cell at Zurich Airport. Single particle analyses will focus on metallic compounds. The particles analyzed herein represent a subset of the emissions composed of the largest particles with a mobility diameter >100 nm due to instrumental restrictions. A vast majority of the analyzed particles was shown to contain elemental carbon, and depending on the engine and the applied thrust the elemental carbon to total carbon ratio ranged from 83% to 99%. The detected metallic compounds were all internally mixed with the soot particles. The most abundant metals in the exhaust were Cr, Fe, Mo, Na, Ca and Al; V, Ba, Co, Cu, Ni, Pb, Mg, Mn, Si, Ti and Zr were also detected. We further investigated potential sources of the ATOFMS-detected metallic compounds using Inductively Coupled Plasma Mass Spectrometry. The potential sources considered were kerosene, engine lubrication oil and abrasion from engine wearing components. An unambiguous source apportionment was not possible because most metallic compounds were detected in several of the analyzed sources.

  3. Long-term rates of chemical weathering and physical erosion from cosmogenic nuclides and geochemical mass balance

    NASA Astrophysics Data System (ADS)

    Riebe, Clifford S.; Kirchner, James W.; Finkel, Robert C.

    2003-11-01

    Quantifying long-term rates of chemical weathering and physical erosion is important for understanding the long-term evolution of soils, landscapes, and Earth's climate. Here we describe how long-term chemical weathering rates can be measured for actively eroding landscapes using cosmogenic nuclides together with a geochemical mass balance of weathered soil and parent rock. We tested this approach in the Rio Icacos watershed, Puerto Rico, where independent studies have estimated weathering rates over both short and long timescales. Results from the cosmogenic/mass balance method are consistent with three independent sets of weathering rate estimates, thus confirming that this approach yields realistic measurements of long-term weathering rates. This approach can separately quantify weathering rates from saprolite and from overlying soil as components of the total. At Rio Icacos, nearly 50% of Si weathering occurs as rock is converted to saprolite; in contrast, nearly 100% of Al weathering occurs in the soil. Physical erosion rates are measured as part of our mass balance approach, making it particularly useful for studying interrelationships between chemical weathering and physical erosion. Our data show that chemical weathering rates are tightly coupled with physical erosion rates, such that the relationship between climate and chemical weathering rates may be obscured by site-to-site differences in the rate that minerals are supplied to soil by physical erosion of rock. One can normalize for variations in physical erosion rates using the "chemical depletion fraction," which measures the fraction of total denudation that is accounted for by chemical weathering. This measure of chemical weathering intensity increases with increasing average temperature and precipitation in data from climatically diverse granitic sites, including tropical Rio Icacos and six temperate sites in the Sierra Nevada, California. Hence, across a wide range of climate regimes, analysis of

  4. A miniature laser ablation mass spectrometer for quantitative in situ chemical composition investigation of lunar surface

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Grimaudo, Valentine; Mezger, Klaus; Moreno-García, Pavel; Riedo, Andreas; Tulej, Marek; Wurz, Peter

    2016-04-01

    The chemical composition of planetary bodies, moons, comets and asteroids is a key to understand their origin and evolution [Wurz,2009]. Measurements of the elemental and isotopic composition of rocks yield information about the formation of the planetary body, its evolution and following processes shaping the planetary surface. From the elemental composition, conclusions about modal mineralogy and petrology can be drawn. Isotope ratios are a sensitive indicator for past events on the planetary body and yield information about origin and transformation of the matter, back to events that occurred in the early solar system. Finally, measurements of radiogenic isotopes make it possible to carry out dating analyses. All these topics, particularly in situ dating analyses, quantitative elemental and highly accurate isotopic composition measurements, are top priority scientific questions for future lunar missions. An instrument for precise measurements of chemical composition will be a key element in scientific payloads of future landers or rovers on lunar surface. We present a miniature laser ablation mass spectrometer (LMS) designed for in situ research in planetary and space science and optimised for measurements of the chemical composition of rocks and soils on a planetary surface. By means of measurements of standard reference materials we demonstrate that LMS is a suitable instrument for in situ measurements of elemental and isotopic composition with high precision and accuracy. Measurements of soil standards are used to confirm known sensitivity coefficients of the instrument and to prove the power of LMS for quantitative elemental analyses [Neuland,2016]. For demonstration of the capability of LMS to measure the chemical composition of extraterrestrial material we use a sample of Allende meteorite [Neuland,2014]. Investigations of layered samples confirm the high spatial resolution in vertical direction of LMS [Grimaudo,2015], which allows in situ studying of past

  5. A pan-European study of capabilities to manage mass casualties from the release of chemical agents: the MASH project.

    PubMed

    Baker, David J; Murray, Virginia S G; Carli, Pierre A

    2013-01-01

    The European Union (EU) Mass Casualties and Health (MASH) project that ran between 2008 and 2010 was designed to study the management of mass casualties from chemical and radiological releases and associated health implications. One area of study for this project concerned arrangements within EU Member States for the management of mass casualties following a chemical release. This was undertaken via a confidential online questionnaire that was sent to selected points of contact throughout the EU. Responses were obtained from 18 states from respondents holding senior positions in chemical planning and incident response. Information gathered shows a lack of uniformity within the EU about the organization of responses to chemical releases and the provision of medical care. This article presents the overall findings of the study demonstrating differences between countries on planning and organization, decontamination, prehospital emergency medical responses, clinical diagnoses, and therapy and aftercare. Although there may be an understandable reluctance from national respondents to share information on security and other grounds, the findings, nevertheless, revealed substantial differences between current planning and operational responses within the EU states for the management of mass chemical casualties. The existing international networks for response to radiation incidents are not yet matched by equivalent networks for chemical responses yet sufficient information was available from the study to identify potential deficiencies, identify common casualty management pathways, and to make recommendations for future operations within the EU. Improvements in awareness and training and the application of modern information and communications will help to remedy this situation. Specialized advanced life support and other medical care for chemical casualties appear lacking in some countries. A program of specialized training and action are required to apply the findings

  6. Hazards of ionising radiation: 100 years of observations on man.

    PubMed Central

    Doll, R.

    1995-01-01

    In November 1895, when Conrad Röntgen serendipitously discovered X-rays, epidemiology was effectively limited to the study of infectious disease. What little epidemiological work was done in other fields was done as part of clinical medicine or under the heading of geographical pathology. The risks from exposure to X-rays and subsequently from other types of ionising radiation were consequently discovered by qualitative association or animal experiment. They did not begin to be quantified in humans until half a century later, when epidemiology emerged as a scientific discipline capable of quantifying risks of non-infectious disease and the scientific world was alerted to the need for assessing the effects of the radiation to which large populations might be exposed by the use of nuclear energy in peace and war. PMID:8519643

  7. Migration levels of PVC plasticisers: Effect of ionising radiation treatment.

    PubMed

    Zygoura, Panagiota D; Paleologos, Evangelos K; Kontominas, Michael G

    2011-09-01

    Migration levels of commercial plasticisers [di-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC)] from polyvinyl chloride (PVC) film into the EU specified aqueous food simulants (distilled water, 3% w/v acetic acid and 10% v/v ethanol) were monitored as a function of time. Migration testing was carried out at 40°C for 10days (EEC, 1993). Determination of the analytes was performed by applying the analytical methodology based on surfactant (Triton X-114) mediated extraction prior to gas chromatographic-flame ionisation detection (GC-FID) recently proposed by our group. The study focuses on the determination of the effect of gamma radiation on plasticiser migration into the selected simulants. PVC cling film used was subjected to ionising treatment with a [(60)Co] source at doses equal to 5, 15 and 25kGy. DEHA and ATBC migration into the EU aqueous simulating solvents was limited, yielding final concentrations in the respective ranges 10-100μg/l and 171-422μg/l; hence, ATBC demonstrated a stronger interaction with all three simulants compared to DEHA. Migration data, with respect to ATBC, showed that the most aggressive simulant seemed to be the 10% ethanol, while in the case of DEHA the 3% aqueous acetic acid exhibited the highest extraction efficiency; distilled water demonstrated the lowest migration in both cases. With regard to PVC treatment with gamma rays, high radiation doses up to 25kGy produced a statistically significant (p<0.05) effect on the migration of both plasticisers.

  8. Serum total testosterone: immunoassay compared with negative chemical ionization gas chromatography-mass spectrometry.

    PubMed

    Fitzgerald, R L; Herold, D A

    1996-05-01

    We have developed an electron capture negative chemical ionization gas chromatography-mass spectrometry (GC-MS) procedure to quantify serum testosterone in the clinically relevant range 0.69-69.3 nmol/L and used this procedure to assess Ciba Corning Diagnostics ACS:180 testosterone immunoassay. The GC-MS method involves liquid-liquid extraction of serum samples and synthesis of a pentafluorobenzyloxime/silyl ether derivative of testosterone with excellent chromatographic and electron capturing properties. The ACS testosterone assay is the first fully automated nonradioactive testosterone immunoassay approved by the US Food and Drug Administration. Patients' specimens (101, 57 males, 44 females) were analyzed by both techniques. A plot of the GC-MS (x) vs ACS (y) testosterone concentrations for men was linear (y = 1.07x + 0.19 nmol/L), showing excellent correlation (r2 = 0.98) between the two assays. Agreement of the two assays for female specimens was poor (y = 0.72x + 1.2 nmol/L), with a poor correlation (r2 = 0.31).

  9. Laser-induced acoustic desorption/atmospheric pressure chemical ionization mass spectrometry.

    PubMed

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

    2011-03-01

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

  10. Mitochondrial protein interactome elucidated by chemical cross-linking mass spectrometry.

    PubMed

    Schweppe, Devin K; Chavez, Juan D; Lee, Chi Fung; Caudal, Arianne; Kruse, Shane E; Stuppard, Rudy; Marcinek, David J; Shadel, Gerald S; Tian, Rong; Bruce, James E

    2017-02-14

    Mitochondrial protein interactions and complexes facilitate mitochondrial function. These complexes range from simple dimers to the respirasome supercomplex consisting of oxidative phosphorylation complexes I, III, and IV. To improve understanding of mitochondrial function, we used chemical cross-linking mass spectrometry to identify 2,427 cross-linked peptide pairs from 327 mitochondrial proteins in whole, respiring murine mitochondria. In situ interactions were observed in proteins throughout the electron transport chain membrane complexes, ATP synthase, and the mitochondrial contact site and cristae organizing system (MICOS) complex. Cross-linked sites showed excellent agreement with empirical protein structures and delivered complementary constraints for in silico protein docking. These data established direct physical evidence of the assembly of the complex I-III respirasome and enabled prediction of in situ interfacial regions of the complexes. Finally, we established a database and tools to harness the cross-linked interactions we observed as molecular probes, allowing quantification of conformation-dependent protein interfaces and dynamic protein complex assembly.

  11. Calibration of a chemical ionization mass spectrometer for the measurement of gaseous sulfuric acid.

    PubMed

    Kürten, Andreas; Rondo, Linda; Ehrhart, Sebastian; Curtius, Joachim

    2012-06-21

    The accurate measurement of the gaseous sulfuric acid concentration is crucial within many fields of atmospheric science. Instruments utilizing chemical ionization mass spectrometry (CIMS) measuring H(2)SO(4), therefore, require a careful calibration. We have set up a calibration source that can provide a stable and adjustable concentration of H(2)SO(4). The calibration system initiates the production of sulfuric acid through the oxidation of SO(2) by OH. The hydroxyl radical is produced by UV photolysis of water vapor. A numerical model calculates the H(2)SO(4) concentration provided at the outlet of the calibration source. From comparison of this concentration and the signals measured by CIMS, a calibration factor is derived. This factor is evaluated to be 1.1 × 10(10) cm(-3), which is in good agreement with values found in the literature for other CIMS instruments measuring H(2)SO(4). The calibration system is described in detail and the results are discussed. Because the setup is external to the CIMS instrument, it offers the possibility for future CIMS intercomparison measurements by providing defined and stable concentrations of sulfuric acid.

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

    PubMed

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

    2013-09-01

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

  13. Mass spectrometric and quantum chemical determination of proton water clustering equilibria

    NASA Astrophysics Data System (ADS)

    Likholyot, Alexander; Lemke, Kono H.; Hovey, Jamey K.; Seward, Terry M.

    2007-05-01

    We report on the thermochemistry of proton hydration by water in the gas phase both experimentally using high-pressure mass spectrometry (HPMS) and theoretically using multilevel G3, G3B3, CBS-Q, CBS-QB3, CBS/QCI-APNO as well as density functional theory (DFT) calculations. Gas phase hydration enthalpies and entropies for protonated water cluster equilibria with up to 7 waters (i.e., n ⩽ 7H 3O +·(H 2O) n) were observed and exhibited non-monotonic behavior for successive hydration steps as well as enthalpy and entropy anomalies at higher cluster rank numbers. In particular, there is a significant jump in the stepwise enthalpies and entropies of cluster formation for n varying from 6 to 8. This behavior can be successfully interpreted using cluster geometries obtained from quantum chemical calculations by considering the number of additional hydrogen bonds formed at each hydration step and simultaneous weakening of ion-solvent interaction with increasing cluster size. The measured total hydration energy for the attachment of the first six water molecules around the hydronium ion was found to account for more than 60% of total bulk hydration free energy.

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

    PubMed Central

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

    2010-01-01

    Laser-induced acoustic desorption (LIAD) was successfully coupled to a conventional atmospheric pressure chemical ionization (APCI) source in a linear quadrupole ion trap mass spectrometer (LQIT). Model compounds representing a wide variety of different types, including basic nitrogen and oxygen compounds, aromatic and aliphatic compounds, as well as unsaturated and saturated hydrocarbons, were tested separately and as a mixture. These model compounds were successfully evaporated into the gas phase by using LIAD and then ionized by using APCI with different reagents. Four APCI reagent systems were tested: the traditionally used mixture of methanol and water, neat benzene, neat carbon disulfide, and nitrogen gas (no liquid reagent). The mixture of methanol and water produced primarily protonated molecules, as expected. However, only the most basic compounds yielded ions under these conditions. In sharp contrast, using APCI with either neat benzene or neat carbon disulfide as the reagent resulted in the ionization of all the analytes studied to predominantly yield stable molecular ions. Benzene yielded a larger fraction of protonated molecules than carbon disulfide, which is a disadvantage. A similar amount of fragmentation was observed for these reagents. When the experiment was performed without a liquid reagent(nitrogen gas was the reagent), more fragmentation was observed. Analysis of a known mixture as well as a petroleum cut was also carried out. In summary, the new experiment presented here allows the evaporation of thermally labile compounds, both polar and nonpolar, without dissociation or aggregation, and their ionization to form stable molecular ions. PMID:21472571

  15. The effect of the mass and initial chemical form of neptunium on its molecular associations in blood and liver.

    PubMed

    Paquet, F; Ramounet, B; Métivier, H; Taylor, D M

    1996-09-01

    The present investigation was aimed at establishing the distribution of neptunium in blood and liver cells as a function of the mass and chemical form of the radionuclide injected. Four groups of rats received intravenous injections of 237Np(V), 237Np(IV), 239Np(V) or 239Np(IV). Twenty-four hours after injection of the radionuclide, subcellular structures of the liver were separated by ultracentrifugation and serum and liver cytosol were subjected to gel permeation chromatography. The intracellular distribution of neptunium in liver depends on the mass of the radionuclide injected; the relative specific activity for 237Np compared to 239Np was 2 in nuclei and 0.5-0.9 in cytosol. By contrast, the initial chemical form of the radionuclide has no significant effect on its intracellular distribution. In cytosol, neptunium was bound mainly by two proteins of molecular weight 450 and 200 kDa, respectively. The former was identified as ferritin, but the latter remains unidentified. In this compartment, no effect of mass or chemical form was seen. In blood, the bulk of the radionuclide was bound to transferrin whatever the mass and initial chemical form injected.

  16. 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...

  17. INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account

    NASA Astrophysics Data System (ADS)

    Kosarev, N. I.; Shaparev, N. Ya

    2006-04-01

    The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo.

  18. Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

    PubMed

    Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

    2014-05-06

    A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.

  19. Variations of the stellar initial mass function in semi-analytical models: implications for the mass assembly and the chemical enrichment of galaxies in the GAEA model

    NASA Astrophysics Data System (ADS)

    Fontanot, Fabio; De Lucia, Gabriella; Hirschmann, Michaela; Bruzual, Gustavo; Charlot, Stéphane; Zibetti, Stefano

    2017-02-01

    In this paper, we investigate the implications of the integrated galaxy-wide stellar initial mass function (IGIMF) approach in the framework of the semi-analytical model GAEA (GAlaxy Evolution and Assembly), which features a detailed treatment of chemical enrichment and stellar feedback. The IGIMF provides an analytic description of the dependence of the stellar IMF shape on the rate of star formation in galaxies. We find that our model with a universal IMF predicts a rather flat [α/Fe]-stellar mass relation. The model assuming the IGIMF, instead, is able to reproduce the observed increase of α-enhancement with stellar mass, in agreement with previous studies. This is mainly due to the fact that massive galaxies are characterized by larger star formation rates at high redshift, leading to stronger α-enhancement with respect to low-mass galaxies. At the same time, the IGIMF hypothesis does not affect significantly the trend for shorter star formation time-scales for more massive galaxies. We argue that in the IGIMF scenario the [α/Fe] ratios are good tracers of the highest star formation events. The final stellar masses and mass-to-light ratio of our model massive galaxies are larger than those estimated from the synthetic photometry assuming a universal IMF, providing a self-consistent interpretation of similar recent results, based on dynamical analysis of local early-type galaxies.

  20. Spatial localisation of curcumin and rapid screening of the chemical compositions of turmeric rhizomes (Curcuma longa Linn.) using Direct Analysis in Real Time-Mass Spectrometry (DART-MS).

    PubMed

    Rahman, A F M Motiur; Angawi, Rihab F; Kadi, Adnan A

    2015-04-15

    Curcumin is a potent antioxidant agent having versatile biological activities is present in turmeric rhizomes (Curcuma longa Linn.). Powder of turmeric rhizomes is consumes as curry spicy worldwide, especially in Asia. In this study, we demonstrate that, bioactive curcumin and its analog demethoxycurcumin are chiefly concentrated in the pith rather than the other parts of the turmeric rhizomes and it was discovered using modern atmospheric ionisation source 'Direct Analysis in Real Time' (DART) connected with an Ion Trap Mass Spectrometry. In addition, all the major components present in turmeric rhizomes were detected in positive and/or in negative ion mode using DART.

  1. Quantitative real-time monitoring of chemical reactions by autosampling flow injection analysis coupled with atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Zhu, Zhenqian; Bartmess, John E; McNally, Mary Ellen; Hoffman, Ron M; Cook, Kelsey D; Song, Liguo

    2012-09-04

    Although qualitative and/or semiquantitative real-time monitoring of chemical reactions have been reported with a few mass spectrometric approaches, to our knowledge, no quantitative mass spectrometric approach has been reported so far to have a calibration valid up to molar concentrations as required by process control. This is mostly due to the absence of a practical solution that could well address the sample overloading issue. In this study, a novel autosampling flow injection analysis coupled with an atmospheric pressure chemical ionization mass spectrometry (FIA/APCI-MS) system, consisting of a 1 μL automatic internal sample injector, a postinjection splitter with 1:10 splitting ratio, and a detached APCI source connected to the mass spectrometer using a 4.5 in. long, 0.042 in. inner diameter (ID) stainless-steel capillary, was thus introduced. Using this system together with an optional FIA solvent modifier, e.g., 0.05% (v/v) isopropylamine, a linear quantitative calibration up to molar concentration has been achieved with 3.4-7.2% relative standard deviations (RSDs) for 4 replicates. As a result, quantitative real-time monitoring of a model reaction was successfully performed at the 1.63 M level. It is expected that this novel autosampling FIA/APCI-MS system can be used in quantitative real-time monitoring of a wide range of reactions under diverse reaction conditions.

  2. Ionisation effect on the electron localisation in the subcycle waveform shaping scheme

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Feng, Zhengpeng; Long, Hua

    2015-03-01

    We have theoretically studied the ionisation effect on the asymmetric dissociation of H+2 exposed to the synthesised multicycle infrared pulses of different wavelengths by solving the time-dependent Schr?dinger equation without using the Born-Oppenheimer approximation. It has been demonstrated that the ionisation does slightly influence the electron localisation for the relatively low pulse intensity (less than 1014 W/cm2). However, our further results show that the ionisation effect becomes much more significant when increasing the pulse intensity, leading to a distinctly different mechanism responsible for the enhancement of the electron localisation.

  3. CHEMICAL COMPOSITION OF INTERMEDIATE-MASS STAR MEMBERS OF THE M6 (NGC 6405) OPEN CLUSTER

    SciTech Connect

    Kılıçoğlu, T.; Albayrak, B.; Monier, R.; Richer, J.; Fossati, L. E-mail: balbayrak@ankara.edu.tr E-mail: Jacques.Richer@umontreal.ca

    2016-03-15

    We present here the first abundance analysis of 44 late B-, A-, and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myr). Low- and medium-resolution spectra, covering the 4500–5840 Å wavelength range, were obtained using the FLAMES/GIRAFFE spectrograph attached to the ESO Very Large Telescopes. We determined the atmospheric parameters using calibrations of the Geneva photometry and by adjusting the H{sub β} profiles to synthetic ones. The abundances of up to 20 chemical elements, from helium to mercury, were derived for 19 late B, 16 A, and 9 F stars by iteratively adjusting synthetic spectra to the observations. We also derived a mean cluster metallicity of [Fe/H] = 0.07 ± 0.03 dex from the iron abundances of the F-type stars. We find that for most chemical elements, the normal late B- and A-type stars exhibit larger star-to-star abundance variations than the F-type stars probably because of the faster rotation of the B and A stars. The abundances of C, O, Mg, Si, and Sc appear to be anticorrelated with that of Fe, while the opposite holds for the abundances of Ca, Ti, Cr, Mn, Ni, Y, and Ba as expected if radiative diffusion is efficient in the envelopes of these stars. In the course of this analysis, we discovered five new peculiar stars: one mild Am, one Am, and one Fm star (HD 318091, CD-32 13109, GSC 07380-01211, CP1), one HgMn star (HD 318126, CP3), and one He-weak P-rich (HD 318101, CP4) star. We also discovered a new spectroscopic binary, most likely a SB2. We performed a detailed modeling of HD 318101, the new He-weak P-rich CP star, using the Montréal stellar evolution code XEVOL which self-consistently treats all particle transport processes. Although the overall abundance pattern of this star is properly reproduced, we find that detailed abundances (in particular the high P excess) resisted modeling attempts even when a range of turbulence profiles and mass-loss rates were considered. Solutions are proposed which are

  4. Chemical Composition of Intermediate-mass Star Members of the M6 (NGC 6405) Open Cluster

    NASA Astrophysics Data System (ADS)

    Kılıçoğlu, T.; Monier, R.; Richer, J.; Fossati, L.; Albayrak, B.

    2016-03-01

    We present here the first abundance analysis of 44 late B-, A-, and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myr). Low- and medium-resolution spectra, covering the 4500-5840 Å wavelength range, were obtained using the FLAMES/GIRAFFE spectrograph attached to the ESO Very Large Telescopes. We determined the atmospheric parameters using calibrations of the Geneva photometry and by adjusting the Hβ profiles to synthetic ones. The abundances of up to 20 chemical elements, from helium to mercury, were derived for 19 late B, 16 A, and 9 F stars by iteratively adjusting synthetic spectra to the observations. We also derived a mean cluster metallicity of [Fe/H] = 0.07 ± 0.03 dex from the iron abundances of the F-type stars. We find that for most chemical elements, the normal late B- and A-type stars exhibit larger star-to-star abundance variations than the F-type stars probably because of the faster rotation of the B and A stars. The abundances of C, O, Mg, Si, and Sc appear to be anticorrelated with that of Fe, while the opposite holds for the abundances of Ca, Ti, Cr, Mn, Ni, Y, and Ba as expected if radiative diffusion is efficient in the envelopes of these stars. In the course of this analysis, we discovered five new peculiar stars: one mild Am, one Am, and one Fm star (HD 318091, CD-32 13109, GSC 07380-01211, CP1), one HgMn star (HD 318126, CP3), and one He-weak P-rich (HD 318101, CP4) star. We also discovered a new spectroscopic binary, most likely a SB2. We performed a detailed modeling of HD 318101, the new He-weak P-rich CP star, using the Montréal stellar evolution code XEVOL which self-consistently treats all particle transport processes. Although the overall abundance pattern of this star is properly reproduced, we find that detailed abundances (in particular the high P excess) resisted modeling attempts even when a range of turbulence profiles and mass-loss rates were considered. Solutions are proposed which are still under

  5. Analytical pyrolysis mass spectrometry: new vistas opened by temperature-resolved in-source PYMS

    NASA Astrophysics Data System (ADS)

    Boon, Jaap J.

    1992-09-01

    Analytical pyrolysis mass spectrometry (PYMS) is introduced and its applications to the analysis of synthetic polymers, biopolymers, biomacromolecular systems and geomacromolecules are critically reviewed. Analytical pyrolysis inside the ionisation chamber of a mass spectrometer, i.e. in-source PYMS, gives a complete inventory of the pyrolysis products evolved from a solid sample. The temperature-resolved nature of the experiment gives a good insight into the temperature dependence of the volatilisation and pyrolytic dissociation processes. Chemical ionisation techniques appear to be especially suitable for the analysis of oligomeric fragments released in early stages of the pyrolysis of polymer systems. Large oligomeric fragments were observed for linear polymers such as cellulose (pentadecamer), polyhydroxyoctanoic acid (tridecamer) and polyhydroxybutyric acid (heneicosamer). New in-source PYMS data are presented on artists' paints, the plant polysaccharides cellulose and xyloglucan, several microbial polyhydroxyalkanoates, wood and enzyme-digested wood, biodegraded roots and a fossil cuticle of Miocene age. On-line and off-line pyrolysis chromatography mass spectrometric approaches are also discussed. New data presented on high temperature gas chromatography--mass spectrometry of deuterio-reduced permethylated pyrolysates of cellulose lead to a better understanding of polysaccharide dissociation mechanisms. Pyrolysis as an on-line sample pretreatment method for organic macromolecules in combination with MS techniques is a very challenging field of mass spectrometry. Pyrolytic dissociation and desorption is not at all a chaotic process but proceeds according to very specific mechanisms.

  6. Chemical structure influence on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux.

    PubMed

    Padgett, Mark C; Tick, Geoffrey R; Carroll, Kenneth C; Burke, William R

    2017-03-01

    The influence of chemical structure on NAPL mixture nonideality evolution, rate-limited dissolution, and contaminant mass flux was examined. The variability of measured and UNIFAC modeled NAPL activity coefficients as a function of mole fraction was compared for two NAPL mixtures containing structurally-different contaminants of concern including toluene (TOL) or trichloroethene (TCE) within a hexadecane (HEXDEC) matrix. The results showed that dissolution from the NAPL mixtures transitioned from ideality for mole fractions >0.05 to nonideality as mole fractions decreased. In particular, the TCE generally exhibited more ideal dissolution behavior except at lower mole fractions, and may indicate greater structural/polarity similarity between the two compounds. Raoult's Law and UNIFAC generally under-predicted the batch experiment results for TOL:HEXDEC mixtures especially for mole fractions ≤0.05. The dissolution rate coefficients were similar for both TOL and TCE over all mole fractions tested. Mass flux reduction (MFR) analysis showed that more efficient removal behavior occurred for TOL and TCE with larger mole fractions compared to the lower initial mole fraction mixtures (i.e. <0.2). However, compared to TOL, TCE generally exhibited more efficient removal behavior over all mole fractions tested and may have been the result of structural and molecular property differences between the compounds. Activity coefficient variability as a function of mole fraction was quantified through regression analysis and incorporated into dissolution modeling analyses for the dynamic flushing experiments. TOL elution concentrations were modeled (predicted) reasonable well using ideal and equilibrium assumptions, but the TCE elution concentrations could not be predicted using the ideal model. Rather, the dissolution modeling demonstrated that TCE elution was better described by the nonideal model whereby NAPL-phase activity coefficient varied as a function of COC mole fraction

  7. Control and Automation of Fluid Flow, Mass Transfer and Chemical Reactions in Microscale Segmented Flow

    NASA Astrophysics Data System (ADS)

    Abolhasani, Milad

    Flowing trains of uniformly sized bubbles/droplets (i.e., segmented flows) and the associated mass transfer enhancement over their single-phase counterparts have been studied extensively during the past fifty years. Although the scaling behaviour of segmented flow formation is increasingly well understood, the predictive adjustment of the desired flow characteristics that influence the mixing and residence times, remains a challenge. Currently, a time consuming, slow and often inconsistent manual manipulation of experimental conditions is required to address this task. In my thesis, I have overcome the above-mentioned challenges and developed an experimental strategy that for the first time provided predictive control over segmented flows in a hands-off manner. A computer-controlled platform that consisted of a real-time image processing module within an integral controller, a silicon-based microreactor and automated fluid delivery technique was designed, implemented and validated. In a first part of my thesis I utilized this approach for the automated screening of physical mass transfer and solubility characteristics of carbon dioxide (CO2) in a physical solvent at a well-defined temperature and pressure and a throughput of 12 conditions per hour. Second, by applying the segmented flow approach to a recently discovered CO2 chemical absorbent, frustrated Lewis pairs (FLPs), I determined the thermodynamic characteristics of the CO2-FLP reaction. Finally, the segmented flow approach was employed for characterization and investigation of CO2-governed liquid-liquid phase separation process. The second part of my thesis utilized the segmented flow platform for the preparation and shape control of high quality colloidal nanomaterials (e.g., CdSe/CdS) via the automated control of residence times up to approximately 5 minutes. By introducing a novel oscillatory segmented flow concept, I was able to further extend the residence time limitation to 24 hours. A case study of a

  8. Calibrated In Situ Measurement of UT/LS Water Vapor Using Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Thornberry, T. D.; Rollins, A.; Gao, R.; Watts, L. A.; Ciciora, S. J.; McLaughlin, R. J.; Fahey, D. W.

    2011-12-01

    Over the past several decades there has been considerable disagreement among in situ water vapor measurements by different instruments at the low part per million (ppm) mixing ratios found in the upper troposphere and lower stratosphere (UT/LS). These discrepancies contribute to uncertainty in our understanding of the microphysics related to cirrus cloud particle nucleation and growth and affect our ability to determine the effect of climate changes on the radiatively important feedback from UT/LS water vapor. To address the discrepancies observed in measured UT/LS water vapor, a new chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor at low mixing ratios. The instrument utilizes a radioactive α particle source to ionize a flow of sample air drawn into the instrument. A cascade of ion-molecule reactions results in the production of protonated water ions proportional to the water vapor mixing ratio that are then detected by the mass spectrometer. The multi-step nature of the ionization mechanism results in a non-linear sensitivity to water vapor, necessitating calibration across the full range of values to be measured. To accomplish this calibration, we have developed a novel calibration scheme using catalytic oxidation of hydrogen to produce well-defined water vapor mixing ratios that can be introduced into the instrument inlet during flight. The CIMS instrument was deployed for the first time aboard the NASA WB-57 high altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April 2011. The sensitivity of the instrument to water vapor was calibrated every ~45 minutes in flight from < 1 to 150 ppm. Analysis of in-flight data demonstrates a typical sensitivity of 2000 Hz/ppm at 4.5 ppm with a signal to noise ratio (2 σ) > 50 for a 1 second measurement. The instrument and its calibration system performed successfully in

  9. Physical and bio-chemical mass-balance model around seafloor cold seepages

    NASA Astrophysics Data System (ADS)

    Yamazaki, T.; Takeuchi, R.; Monoe, D.; Oomi, T.; Nakata, K.; Fukushima, T.

    2007-12-01

    Natural cold seepages are characterized as rapid upward transports of methane from deeper part of geological structures to the seafloors. Prior to reach the seafloors, when methane meets downwards diffusing seawater sulfate, it is oxidized anaerobically by a consortium of microorganisms that use sulfate as an oxidant, producing sulfide. The anaerobic oxidation of methane and anaerobic sulfate reduction are clarified as a coupled biological activity. A significant portion of the bicarbonate produced after the sulfate reduction as authigenic carbonate, mainly aragonite and high-Mg calcite, near the seafloor. Where the methane fluxes are much, these anaerobic reactions occur just beneath the seafloor. There, usually sulfur oxidizing microorganisms are visible on the seafloor just above the coupled consortium of microorganisms. They are called bacterial mats. When the fluxes too much, direct methane bubbling occurs and chemosynthesis-immobilization communities such as tubeworms and clams distribute around the bubbling locations with the bacterial mats. The physical and bio-chemical mass-balance model around cold seepages on seafloor and in water column has been studied by the authors and some preliminary results were reported (Yamazaki et al., 2005 and 2006; Takeuchi et al., 2007). The approach is to analyze the existing field observation and numerical modeling studies of cold seepages and to create a new physical and bio-chemical mass-balance model in the environment. The model is separated into three parts. They are methane supply, seafloor ecosystem, and water column units. The seafloor ecosystem unit has been improved to analyze the unsteady formation processes of the ecosystem. The time dependencies of formations of the consortium of microorganisms (AOM), the chemosynthetic community, and bicarbonates examined with the improved model are introduced. After the bubbling from seafloor, the methane bubble jet blows up in the water column due to the buoyancy. Then the

  10. Detection of stanozolol in hair by negative ion chemical ionization mass spectrometry.

    PubMed

    Höld, K M; Wilkins, D G; Crouch, D J; Rollins, D E; Maes, R A

    1996-10-01

    Stanozolol is an anabolic androgenic steroid occasionally abused by athletes. A sensitive, specific, and reproducible method for the quantitative determination of stanozolol in hair has been developed. After the addition of stanozolol-d3 as the internal standard, hair samples (10-25 mg) were digested with 2 mL of 1N NaOH at 65 degrees C for at least 2 h. Digest solutions were then extracted using solid-phase extraction. The eluents were evaporated, a mixture of N-methyl-N-trimethylsilylhepta-fluorobutryamide (MSHFBA) and trimethylsilylimidazole (TSIM) (1000:20, v/v) was added, and the mixture heated at 80 degrees C for 5 minutes. After cooling to room temperature, N-methyl-bisheptafluorobutyramide (MBHFBA) was added and the mixture heated at 80 degrees C for 30 min. The derivatized extracts were analyzed on a Finnigan MATTM 4500 mass spectrometer in the negative chemical ionization mode. Chromatographic separation was achieved with helium carrier gas on a HP-1 capillary column (15 m x 0.2-mm i.d.; 33-microns film thickness). The assay was capable of reliably quantitating 50 pg/mg of stanozolol and was linear to 2500 pg/mg. Intra-assay precision was 13.2% at 50 pg/mg and 6.6% at 2500 pg/mg. Interassay precision was 13.7% at 50 pg/mg and 6.1% at 2500 pg/mg. This method has been applied to the analysis of stanozolol incorporated into rat hair. Male Long-Evans rats were given stanozolol 20 mg/kg intraperitoneally once daily for 3 days. The mean concentrations of stanozolol in the rat hair collected on day 14 were 362.4 +/- 332.4 pg/mg in pigmented hair and 90.0 +/- 46.9 pg/mg in nonpigmented hair. These data demonstrate that stanozolol is incorporated preferentially into pigmented hair.

  11. Atmospheric Amines and Ammonia Measured with a Chemical Ionization Mass Spectrometer (CIMS)

    SciTech Connect

    You, Y.; Kanawade, V. P.; de Gouw, J. A.; Guenther, Alex B.; Madronich, Sasha; Sierra-Hernandez, M. R.; Lawler, M.; Smith, James N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, Eric S.; Porcelli, L.; Brune, W. H.; Goldstein, Allen H.; Lee, S.-H

    2014-11-19

    We report ambient measurements of amines and ammonia with a fast response chemical ionization mass spectrometer (CIMS) in a Southeastern U.S. forest in Alabama and a moderately polluted Midwestern site during the summer. In the Alabama forest, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected on a daily basis. C3-amines and ammonia showed similar diurnal trends and temperature and wind direction dependences, and were not associated with transported CO and SO2 plumes. Consistent with temperature dependences, amine and ammonia in the gas and aerosol phases showed opposite diurnal trends, indicating gas-to-particle partitioning of amines and ammonia. Temperature dependences also imply reversible processes of amines and ammonia evaporation from soil surfaces in daytime and deposition of amines and ammonia to soil surfaces at nighttime. Various amines (C1-C6) at the pptv level were observed in the transported biomass burning plumes, showing that biomass burning can be a substantial source of amines in the Southeast U.S. At the moderately polluted Kent site, higher concentrations of amines (C1-C6, from pptv to tens of pptv) and ammonia (up to 6 ppbv) were detected. Diurnal variations of C1- to C3-amines and ammonia were correlated with the ambient temperature. C4- to C6-amines showed abrupt increases during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Lower amine concentrations at the rural forested site highlight the importance of constraining anthropogenic sources of amines.

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

    NASA Astrophysics Data System (ADS)

    Harris, Glenn A.

    Molecular ionization is owed much of its development from the early implementation of electron ionization (EI). Although dramatically increasing the library of compounds discovered, an inherent problem with EI was the low abundance of molecular ions detected due to high fragmentation leading to the difficult task of the correct chemical identification after mass spectrometry (MS). These problems stimulated the research into new ionization methods which sought to "soften" the ionization process. In the late 1980s the advancements of ionization techniques was thought to have reached its pinnacle with both electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). Both ionization techniques allowed for "soft" ionization of large molecular weight and/or labile compounds for intact characterization by MS. Albeit pervasive, neither ESI nor MALDI can be viewed as "magic bullet" ionization techniques. Both techniques require sample preparation which often included native sample destruction, and operation of these techniques took place in sealed enclosures and often, reduced pressure conditions. New open-air ionization techniques termed "ambient MS" enable direct analysis of samples of various physical states, sizes and shapes. One particular technique named Direct Analysis In Real Time (DART) has been steadily growing as one of the ambient tools of choice to ionize small molecular weight (< 1000 Da) molecules with a wide range of polarities. Although there is a large list of reported applications using DART as an ionization source, there have not been many studies investigating the fundamental properties of DART desorption and ionization mechanisms. The work presented in this thesis is aimed to provide in depth findings on the physicochemical phenomena during open-air DART desorption and ionization MS and current application developments. A review of recent ambient plasma-based desorption/ionization techniques for analytical MS is presented in

  13. Deciphering chemical interactions between Glycyrrhizae Radix and Coptidis Rhizoma by liquid chromatography with transformed multiple reaction monitoring mass spectrometry.

    PubMed

    Li, Zhenhao; Liu, Ting; Liao, Jie; Ai, Ni; Fan, Xiaohui; Cheng, Yiyu

    2017-03-01

    In this study, we propose an integrated strategy for the efficient identification and quantification of herbal constituents using liquid chromatography with mass spectrometry. First, liquid chromatography with quadrupole time-of-flight mass spectrometry was employed for the chemical profiling of herbs, where a targeted following nontargeted approach was developed to detect trace constituents by using structural correlations and extracted ion chromatograms. Next, ion pairs and parameters of MS(2) of quadrupole time-of-flight mass spectrometry were selected to design multiple reaction monitoring transitions for the identified compounds on liquid chromatography with triple quadrupole mass spectrometry. The relative concentration of each constituent was then calculated using a semiquantitative calibration curve. The proposed strategy was applied in a study of chemical interactions between Glycyrrhizae Radix and Coptidis Rhizoma. A total of 140 compounds were identified or tentatively characterized from the herbs, 132 of which were relatively quantified. The visualized quantitative results clearly showed codecoction produced significant constituent concentration variations especially for those with a low polarity. The case study also indicated that the present methodology could provide a reliable, accurate, and labor-saving solution for chemical studies of herbal medicines.

  14. Detection of nerve agents using proton transfer reaction mass spectrometry with ammonia as reagent gas.

    PubMed

    Ringer, Joachim M

    2013-01-01

    The chemical warfare agents (CWA) Sarin, Soman, Cyclosarin and Tabun were characterised by proton transfer mass spectrometry (PTRMS). It was found that PTRMS is a suitable technique to detect nerve agents highly sensitively, highly selectively and in near real-time. Methods were found to suppress molecule fragmentation which is significant under PTRMS hollow cathode ionisation conditions. In this context, the drift voltage (as one of the most important system parameters) was varied and ammonia was introduced as an additional chemical reagent gas. Auxiliary chemicals such as ammonia affect ionisation processes and are quite common in context with detectors for CWAs based on ion mobility spectrometry (IMS). With both, variation of drift voltage and ammonia as the reagent gas, fragmentation can be suppressed effectively. Suppression of fragmentation is crucial particularly concerning the implementation of an algorithm for automated agent identification in field applications. On the other hand, appearance of particular fragments might deliver additional information. Degradation and rearrangement products of nerve agents are not distinctive for the particular agent but for the chemical class they belong to. It was found that switching between ammonia doped and ordinary water ionisation chemistry can easily be performed within a few seconds. Making use of this effect it is possible to switch between fragment and molecular ion peak spectra. Thus, targeted fragmentation can be used to confirm identification based only on single peak detection. PTRMS turned out to be a promising technique for future CWA detectors. In terms of sensitivity, response time and selectivity (or confidence of identification, respectively) PTRMS performs as a bridging technique between IMS and GC-MS.

  15. Mass Spectrometry Applications for the Identification and Quantitation of Biomarkers Resulting from Human Exposure to Chemical Warfare Agents

    NASA Astrophysics Data System (ADS)

    Smith, J. Richard; Capacio, Benedict R.

    In recent years, a number of analytical methods using biomedical samples such as blood and urine have been developed for the verification of exposure to chemical warfare agents. The majority of methods utilize gas or liquid chromatography in conjunction with mass spectrometry. In a small number of cases of suspected human exposure to chemical warfare agents, biomedical specimens have been made available for testing. This chapter provides an overview of biomarkers that have been verified in human biomedical samples, details of the exposure incidents, the methods utilized for analysis, and the biomarker concentration levels determined in the blood and/or urine.

  16. Detection of trace levels of triclopyr using capillary gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.

    PubMed

    Begley, P; Foulger, B E

    1988-04-01

    Triclopyr, after esterification, is shown to be a suitable candidate for detection by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry forming a characteristic carboxylate anion which offers a high detection sensitivity. A detection limit of 70 fg reaching the ionizer is indicated. Low backgrounds and an absence of chemical interferences are shown for vegetation extracts, using a simple method of extraction and derivatisation. A similar behaviour is demonstrated for 2,4-D and 2,4,5-T.

  17. Ionisation Chambers and Secondary Emission Monitors at the PROSCAN Beam Lines

    NASA Astrophysics Data System (ADS)

    Dölling, Rudolf

    2006-11-01

    PROSCAN, the dedicated new medical facility at PSI using proton beams for the treatment of deep seated tumours and eye melanoma, is now in the commissioning phase. Air filled ionisation chambers in several configurations are used as current monitors, profile monitors, halo, position and loss monitors at the PROSCAN beam lines. Similar monitors based on secondary emission are used for profile and current measurements in the regime where saturation deteriorates the accuracy of the ionisation chambers.

  18. Direct chemical profiling of olive (Olea europaea) fruit epicuticular waxes by direct electrospray-ultrahigh resolution mass spectrometry.

    PubMed

    Vichi, Stefania; Cortés-Francisco, Nuria; Romero, Agustí; Caixach, Josep

    2015-03-01

    In the present paper, an electrospray ionization (ESI)-Orbitrap method is proposed for the direct chemical profiling of epicuticular wax (EW) from Olea europaea fruit. It constitutes a rapid and efficient tool suitable for a wide-ranging screening of a large number of samples. In a few minutes, the method provides a comprehensive characterization of total EW extracts, based on the molecular formula of their components. Accurate mass measurements are obtained by ultrahigh resolution mass spectrometry, and compositional restrictions are set on the basis of the information available from previous studies of olive EW. By alternating positive and negative ESI modes within the same analysis, complementary results are obtained and a wide range of chemical species is covered. This provides a detailed compositional overview that otherwise would only be available by applying multiple analytical techniques.

  19. Medical effects and risks of exposure to ionising radiation.

    PubMed

    Mettler, Fred A

    2012-03-01

    Effects and risk from exposure to ionising radiation depend upon the absorbed dose, dose rate, quality of radiation, specifics of the tissue irradiated and other factors such as the age of the individual. Effects may be apparent almost immediately or may take decades to be manifest. Cancer is the most important stochastic effect at absorbed doses of less than 1 Gy. The risk of cancer induction varies widely across different tissues; however, the risk of fatal radiation-induced cancer for a general population following chronic exposure is about 5% Sv(-1). Quantification of cancer risk at doses of less than 0.1 Gy remains problematic. Hereditary risks from irradiation that might result in effects to offspring of humans appear to be much lower and any such potential risks can only be estimated from animal models. At high doses (over 1 Gy) cell killing and modification causes deterministic effects such as skin burns, and bone marrow depression, in which case immunosuppression becomes a critical issue. Acute whole body penetrating gamma irradiation at doses in excess of 2 Gy results in varying degrees of acute radiation sickness and doses over 10 Gy are usually lethal as a result of combined organ injury.

  20. Dosimetry of ionising radiation in modern radiation oncology

    NASA Astrophysics Data System (ADS)

    Kron, Tomas; Lehmann, Joerg; Greer, Peter B.

    2016-07-01

    Dosimetry of ionising radiation is a well-established and mature branch of physical sciences with many applications in medicine and biology. In particular radiotherapy relies on dosimetry for optimisation of cancer treatment and avoidance of severe toxicity for patients. Several novel developments in radiotherapy have introduced new challenges for dosimetry with small and dynamically changing radiation fields being central to many of these applications such as stereotactic ablative body radiotherapy and intensity modulated radiation therapy. There is also an increasing awareness of low doses given to structures not in the target region and the associated risk of secondary cancer induction. Here accurate dosimetry is important not only for treatment optimisation but also for the generation of data that can inform radiation protection approaches in the future. The article introduces some of the challenges and highlights the interdependence of dosimetric calculations and measurements. Dosimetric concepts are explored in the context of six application fields: reference dosimetry, small fields, low dose out of field, in vivo dosimetry, brachytherapy and auditing of radiotherapy practice. Recent developments of dosimeters that can be used for these purposes are discussed using spatial resolution and number of dimensions for measurement as sorting criteria. While dosimetry is ever evolving to address the needs of advancing applications of radiation in medicine two fundamental issues remain: the accuracy of the measurement from a scientific perspective and the importance to link the measurement to a clinically relevant question. This review aims to provide an update on both of these.

  1. Block microstructural characterization of copolymers formed from fluorinated and non-fluorinated alkyl polyisocyanates using desorption chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chen, Guodong; Cooks, R. Graham; Jha, Salil K.; Oupicky, David; Green, Mark M.

    1997-11-01

    Homopolymers and copolymers of 1-isocyanato-4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononane (monomer F) and n-hexylisocyanate (monomer H) were examined by desorption chemical ionization mass spectrometry (DCI-MS) to obtain information on the monomer distribution in the copolymers. Tandem mass spectrometry (MS/MS) was used to characterize ions generated by DCI in the mass spectrometer ion source; ammonia and isobutane were selected as chemical ionization (CI) reagent gases. The major peaks in the ammonia DCI mass spectrum of poly(4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononyl)isocyanate (poly (F)) are protonated and ammoniated trimers. This result suggests that on pyrolytic degradation poly (F) forms cyclic trimers as do alkyl isocyanate polymers. The isobutane DCI mass spectra display the characteristic alkene elimination sequence characteristic of poly(n-hexyl)isocyanate and poly(2,6-dimethylheptyl)isocyanate but with additional extensive fragmentation. The major fragment ion is the protonated monomer. The monomer distributions in copolymers comprised of monomer F and monomer H were deduced from the abundances of various protonated and ammoniated trimers in the ammonia DCI mass spectra using Markovian statistics. Both soluble and insoluble copolymer samples were isolated and found to have non-random monomer distributions. The soluble fraction is dominated by monomer H blocks while the insoluble fraction also contains a majority of monomer H blocks but relatively more monomer F blocks. This forms an example in the polyisocyanates, which hitherto exhibited only random copolymerization, of a non-living method of polymerization yielding a block microstructure for a mixture of two monomers with virtually identical polymerizable functions. Mass spectrometry offers information on chain microstructure which would be unavailable by other means.

  2. Flow reactor and triple quadrupole mass spectrometer investigations of negative ion reactions involving nitric acid - Implications for atmospheric HNO3 detection by chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Arnold, F.

    1991-07-01

    The ion-molecule reactions on which Active Chemical Ionization Mass Spectrometry (ACIMS) measurements of atmospheric nitric acid are based are presently subjected to product-ion distribution and rate coefficient measurements. The results obtained indicate that while previous stratospheric nitric acid measurements were not impared by collisional dissociation processes, these processes may have played a major role during previous tropospheric measurements: leading to an undereestimation of nitric acid concentrations. A novel ACIMS ion source has been developed in order to avoid these problems.

  3. Underwater mass spectrometers for in situ chemical analysis of the hydrosphere.

    PubMed

    Short, R T; Fries, D P; Kerr, M L; Lembke, C E; Toler, S K; Wenner, P G; Byrne, R H

    2001-06-01

    Underwater mass spectrometry systems can be used for direct in situ detection of volatile organic compounds and dissolved gases in oceans, lakes, rivers and waste-water streams. In this work we describe the design and operation of (1) a linear quadrupole mass filter and (2) a quadrupole ion trap mass spectrometer interfaced, in each case, with a membrane introduction/fluid control system and packaged for underwater operation. These mass spectrometry systems can operate autonomously, or under user control via a wireless rf link. Detection limits for each system were determined in the laboratory using pure solutions. The quadrupole mass filter system provides detection limits in the 1-5 ppb range with an upper mass limit of 100 amu. Its power requirement is approximately 95 Watts. The ion trap system has detection limits well below 1 ppb, an upper mass limit of 650 amu and MS/MS capability. Its power consumption is on the order of 150 Watts. The present membrane limits analysis to non-polar compounds (<300 amu) with analysis cycles of 5-15 minutes. Deployments of both types of instruments are described, along with a discussion of the challenges associated with in-water mass spectrometry and descriptions of alternative in-water mass spectrometer configurations.

  4. The influence of Oort clouds on the mass and chemical balance of the interstellar medium

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan; Shull, J. Michael

    1990-01-01

    The contribution of stellar encounters and interstellar erosion to comet cloud mass injection to the ISM is calculated. It is shown that evaporative mass loss from passing stars and SNe results in an average Galactic mass injection rate of up to 10 to the -5th solar mass/yr if such clouds are frequent around solar-type stars. Cometary erosion by interstellar grains produces an injection rate of 10 to the -5th to 10 to the -4th solar mass/yr. An injection rate of 2 x 10 to the -5th solar mass/yr is calculated. Each of these rates could be increased by a factor of about 15 if the comet clouds contain a significant amount of smaller debris. It is concluded that the total mass injection rate of material to the ISM by comet clouds is small compared to other ISM mass injection sources. Comet cloud mass loss to the ISM could be responsible for a sizeable fraction of the metal and dust abundances of the ISM if Oort clouds are common.

  5. The influence of Oort clouds on the mass and chemical balance of the interstellar medium

    SciTech Connect

    Stern, S.A.; Shull, J.M. )

    1990-08-01

    The contribution of stellar encounters and interstellar erosion to comet cloud mass injection to the ISM is calculated. It is shown that evaporative mass loss from passing stars and SNe results in an average Galactic mass injection rate of up to 10 to the -5th solar mass/yr if such clouds are frequent around solar-type stars. Cometary erosion by interstellar grains produces an injection rate of 10 to the -5th to 10 to the -4th solar mass/yr. An injection rate of 2 x 10 to the -5th solar mass/yr is calculated. Each of these rates could be increased by a factor of about 15 if the comet clouds contain a significant amount of smaller debris. It is concluded that the total mass injection rate of material to the ISM by comet clouds is small compared to other ISM mass injection sources. Comet cloud mass loss to the ISM could be responsible for a sizeable fraction of the metal and dust abundances of the ISM if Oort clouds are common. 50 refs.

  6. Pattern of aerosol mass loading and chemical composition over the atmospheric environment of an urban coastal station

    NASA Astrophysics Data System (ADS)

    Bindu, G.; Nair, Prabha R.; Aryasree, S.; Hegde, Prashant; Jacob, Salu

    2016-02-01

    Aerosol sampling was carried out at four locations in and around Cochin (9°58‧ N, 76°17‧ E), an urban area, located on the southwest coast of India. The gravimetric estimates of aerosol mass loading showed wide range from 78 μg m-3 to >450 μg m-3, occasionally reaching values >500 μg m-3, associated with regional source characteristics. Most of the values were above the air quality standard. Both boundary layer and synoptic scale airflow pattern play role in the temporal features in aerosol mass loading and chemical composition. Chemical analysis of the aerosol samples were done for anionic species viz; F-, Cl-, Br-, NO2-,   NO3-,   PO43-,   SO42- and metallic/cationic species viz; Na, Ca, K, Mg, NH4+, Fe, Al, Cu, Mg, Pb, etc using Ion Chromatography, Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma- Atomic Emission Spectroscopy (ICP-AES). At all the locations, extremely high mass concentration of SO42- was observed with the mean value of 13±6.4 μg m-3 indicating the strong anthropogenic influence. Statistical analysis of the chemical composition data was carried out and the principal factors presented. Seasonal variation of these chemical species along with their percentage contributions and regional variations were also examined. Increase in level of Na in aerosol samples indicated the influence of monsoonal activity. Most of the species showed mass concentrations well above those measured over another coastal site Thiruvananthapuram (8°29‧ N, 76°57‧ E) situated ~220 km south of Cochin revealing the highly localized aerosol features.

  7. The chemical evolution of local star-forming galaxies: radial profiles of ISM metallicity, gas mass, and stellar mass and constraints on galactic accretion and winds

    NASA Astrophysics Data System (ADS)

    Kudritzki, Rolf-Peter; Ho, I.-Ting; Schruba, Andreas; Burkert, Andreas; Zahid, H. Jabran; Bresolin, Fabio; Dima, Gabriel I.

    2015-06-01

    The radially averaged metallicity distribution of the interstellar medium (ISM) and the young stellar population of a sample of 20 disc galaxies is investigated by means of an analytical chemical evolution model which assumes constant ratios of galactic wind mass-loss and accretion mass gain to star formation rate. Based on this model, the observed metallicities and their gradients can be described surprisingly well by the radially averaged distribution of the ratio of stellar mass to ISM gas mass. The comparison between observed and model-predicted metallicity is used to constrain the rate of mass-loss through galactic wind and accretion gain in units of the star formation rate. Three groups of galaxies are found: galaxies with either mostly winds and only weak accretion, or mostly accretion and only weak winds, and galaxies where winds are roughly balanced by accretion. The three groups are distinct in the properties of their gas discs. Galaxies with approximately equal rates of mass-loss and accretion gain have low metallicity, atomic-hydrogen-dominated gas discs with a flat spatial profile. The other two groups have gas discs dominated by molecular hydrogen out to 0.5 to 0.7 isophotal radii and show a radial exponential decline, which is on average steeper for the galaxies with small accretion rates. The rates of accretion ( ≲ 1.0 × SFR) and outflow ( ≲ 2.4 × SFR) are relatively low. The latter depend on the calibration of the zero-point of the metallicity determination from the use of H II region strong emission lines.

  8. New approaches for the chemical and physical characterization of aerosols using a single particle mass spectrometry based technique

    NASA Astrophysics Data System (ADS)

    Spencer, Matthew Todd

    Aerosols affect the lives of people every day. They can decrease visibility, alter cloud formation and cloud lifetimes, change the energy balance of the earth and are implicated in causing numerous health problems. Measuring the physical and chemical properties of aerosols is essential to understand and mitigate any negative impacts that aerosols might have on climate and human health. Aerosol time-of-flight mass spectrometry (ATOFMS) is a technique that measures the size and chemical composition of individual particles in real time. The goal of this dissertation is to develop new and useful approaches for measuring the physical and/or chemical properties of particles using ATOFMS. This has been accomplished using laboratory experiments, ambient field measurements and sometimes comparisons between them. A comparison of mass spectra generated from petrochemical particles was made to light duty vehicle (LDV) and heavy duty diesel vehicle (HDDV) particle mass spectra. This comparison has given us new insight into how to differentiate between particles from these two sources. A method for coating elemental carbon (EC) particles with organic carbon (OC) was used to generate a calibration curve for quantifying the fraction of organic carbon and elemental carbon on particles using ATOFMS. This work demonstrates that it is possible to obtain quantitative chemical information with regards to EC and OC using ATOFMS. The relationship between electrical mobility diameter and aerodynamic diameter is used to develop a tandem differential mobility analyzer-ATOFMS technique to measure the effective density, size and chemical composition of particles. The method is applied in the field and gives new insight into the physical/chemical properties of particles. The size resolved chemical composition of aerosols was measured in the Indian Ocean during the monsoonal transition period. This field work shows that a significant fraction of aerosol transported from India was from biomass

  9. Chemical residues in Dolphins from the US Atlantic coast including atlantic bottlenose obtained during the 1987/88 mass mortality

    SciTech Connect

    Kuehl, D.W.; Haebler, R.; Potter, C.

    1991-01-01

    Bottlenose dolphins (Tursiops truncatus) collected during the 1987/88 mass mortality event along the Atlantic coast of the United States have been analyzed for anthropogenic chemical contaminants. Average contaminant concentrations in adult males were higher than the average concentrations measured in adult females. Females could be divided into two groups by contaminant concentrations, one with low concentrations, and another with concentrations 4.4 times (PCBs) to 8.9 times (p,p'-DDE) greater. Contaminant concentrations in bottlenose were generally greater than the concentrations measured in either common (Delphinus delphis) or white-sided (Lagernorhynchus acutus) dolphins from the western North Atlantic Ocean. A subset of animals screened for unusual chemical contaminants showed that numerous polybrominated chemicals were present, including polybrominated biphenyls and diphenyl ethers not previously found in marine mammals from U.S. coastal waters.

  10. The advancement of chemical cross-linking and mass spectrometry for structural proteomics: from single proteins to protein interaction networks.

    PubMed

    Sinz, Andrea

    2014-12-01

    During the last 15 years, chemical cross-linking combined with mass spectrometry (MS) and computational modeling has advanced from investigating 3D-structures of isolated proteins to deciphering protein interaction networks. In this article, the author discusses the advent, the development and the current status of the chemical cross-linking/MS strategy in the context of recent technological developments. A direct way to probe in vivo protein-protein interactions is by site-specific incorporation of genetically encoded photo-reactive amino acids or by non-directed incorporation of photo-reactive amino acids. As the chemical cross-linking/MS approach allows the capture of transient and weak interactions, it has the potential to become a routine technique for unraveling protein interaction networks in their natural cellular environment.

  11. APOGEE Chemical Tagging Constraint on the Maximum Star Cluster Mass in the Alpha-enhanced Galactic Disk

    NASA Astrophysics Data System (ADS)

    Ting, Yuan-Sen; Conroy, Charlie; Rix, Hans-Walter

    2016-01-01

    Stars born from the same molecular cloud should be nearly homogeneous in their element abundances. The concept of chemical tagging is to identify members of disrupted clusters by their clustering in element abundance space. Chemical tagging requires large samples of stars with precise abundances for many individual elements. With uncertainties of {σ }[X/{{Fe}]} and {σ }[{Fe/{{H}}]}≃ 0.05 for 10 elements measured for \\gt {10}4 stars, the APOGEE DR12 spectra may be the first well-suited data set to put this idea into practice. We find that even APOGEE data offer only ˜500 independent volume elements in the 10-dimensional abundance space, when we focus on the α-enhanced Galactic disk. We develop and apply a new algorithm to search for chemically homogeneous sets of stars against a dominant background. By injecting star clusters into the APOGEE data set, we show that chemically homogeneous clusters with masses ≳ 3× {10}7 {M}⊙ would be easily detectable and yet no such signal is seen in the data. By generalizing this approach, we put a first abundance-based constraint on the cluster mass function for the old disk stars in the Milky Way.

  12. Chemical characterization of submicron aerosol particles during wintertime in a northwest city of China using an Aerodyne aerosol mass spectrometry.

    PubMed

    Zhang, Xinghua; Zhang, Yangmei; Sun, Junying; Yu, Yangchun; Canonaco, Francesco; Prévôt, Andre S H; Li, Gang

    2017-03-01

    An Aerodyne quadrupole aerosol mass spectrometry (Q-AMS) was utilized to measure the size-resolved chemical composition of non-refractory submicron particles (NR-PM1) from October 27 to December 3, 2014 at an urban site in Lanzhou, northwest China. The average NR-PM1 mass concentration was 37.3 μg m(-3) (ranging from 2.9 to 128.2 μg m(-3)) under an AMS collection efficiency of unity and was composed of organics (48.4%), sulfate (17.8%), nitrate (14.6%), ammonium (13.7%), and chloride (5.7%). Positive matrix factorization (PMF) with the multi-linear engine (ME-2) solver identified six organic aerosol (OA) factors, including hydrocarbon-like OA (HOA), coal combustion OA (CCOA), cooking-related OA (COA), biomass burning OA (BBOA) and two oxygenated OA (OOA1 and OOA2), which accounted for 8.5%, 20.2%, 18.6%, 12.4%, 17.8% and 22.5% of the total organics mass on average, respectively. Primary emissions were the major sources of fine particulate matter (PM) and played an important role in causing high chemically resolved PM pollution during wintertime in Lanzhou. Back trajectory analysis indicated that the long-range regional transport air mass from the westerly was the key factor that led to severe submicron aerosol pollution during wintertime in Lanzhou.

  13. Optimized electron-optical system of a static mass-spectrometer for simultaneous isotopic and chemical analysis

    NASA Astrophysics Data System (ADS)

    Gall', L. N.; Masyukevich, S. V.; Sachenko, V. D.; Gall', N. R.

    2016-01-01

    A new approach to control the linear dimensions of analytical electrophysical systems is suggested. This approach uses the lens properties of electron-optical elements with a curvilinear axis. It is shown that such an approach can be effectively applied, in particular, to synthesize ion-optical systems (IOSs) for static magnetic mass spectrometers and can be implemented owing to off-axis fundamental points, the "poles" of an electron-optical system, introduced earlier by one of the authors. The capabilities of the new approach are demonstrated with the synthesis of the IOS of a static mass spectrometer dedicated for isotopic and chemical analysis with an increased resolution. A new IOS not only provides desired high ion-optical parameters at decreased dimensions of the mass spectrometer as a whole but also makes it possible to loosen requirements for the manufacturing accuracy of IOS main elements.

  14. Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical Warfare Agent Sulfur Mustard

    DTIC Science & Technology

    2002-05-16

    Title of Thesis: “Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid...TITLE AND SUBTITLE Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical...phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fibers were investigated to determine the

  15. Chemical Safety Alert: First Responders’ Environmental Liability Due To Mass Decontamination Runoff

    EPA Pesticide Factsheets

    CERCLA's good Samaritan provisions protect responders such as the Chemical Weapons Improved Response Team during lifesaving actions. Once imminent threats are addressed, responders should contain contamination and avoid/mitigate environmental consequences.

  16. Test beam results of micro channel plates in 'ionisation mode' for the detection of single charged particle and electromagnetic showers

    SciTech Connect

    Barnyakov, A.; Barnyakov, M.; Brianza, L.; Ghezzi, A.; Gotti, C.; Govoni, P.; Martelli, A.; Marzocchi, B.; Pigazzini, S.; Tabarelli de Fatis, T.; Trevisani, N.; Cavallari, F.; Del Re, D.; Gelli, S.; Jorda Lope, C.; Meridiani, P.; Organtini, G.; Paramatti, R.; Pernie, L.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.

    2015-07-01

    IMCP is an R and D project aimed at the exploitation of secondary emission of electrons from the surface of microchannel plates (MCP) for fast timing of showers in high rate environments. The usage of MCPs in 'ionisation' mode has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The fast time resolution of MCPs exceeds anything that has been previously used in calorimeters, and, if exploited effectively, could aid in the event reconstruction at high luminosities. Results from tests with electrons with energies up to 150 GeV of MCP devices with different characteristics will be presented, in particular detection efficiency and time resolution. (authors)

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

    PubMed Central

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

    2011-01-01

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

  18. Biological and chemical weapons of mass destruction: updated clinical therapeutic countermeasures since 2003.

    PubMed

    Pettineo, Christopher; Aitchison, Robert; Leikin, Scott M; Vogel, Stephen N; Leikin, Jerrold B

    2009-01-01

    The objective of this article is to provide updated treatment options for bioterrorism agents. This updated synopsis includes recent clinical cases and treatment recommendations that have arisen in the last 5 years. The decontamination, treatment, and disposition of these biologic and chemical agents are presented alphabetically by agent type: biologic, chemical, and radiologic/nuclear. The information provided outlines only new treatment options since 2003.

  19. Chemical Ionization Mass Spectrometry Techniques for Measurements of Gas-Phase Ammonia

    NASA Astrophysics Data System (ADS)

    Nowak, J. B.; Neuman, J. A.; Yoshida, K.; Ryerson, T. B.; Huey, L. G.; Tanner, D. J.; Sjostedt, S. J.; Hubler, G.; Fortin, T. J.; Sueper, D. J.; Fehsenfeld, F. C.

    2005-12-01

    Chemical Ionization Mass Spectrometry (CIMS) can be a highly selective technique with fast time response for measuring many atmospheric trace gases (e.g., hydroxyl radical (OH), sulfuric acid (H2SO4), nitric acid (HNO3)). CIMS is highly versatile and has been used under a wide variety of conditions with many different ion-molecule detection schemes, even for detecting the same molecule. Because of its high proton affinity (853.6 kJ/mol), ammonia (NH3) is another ideal candidate for detection by CIMS. NH3, the dominant gas-phase base in the atmosphere, is a precursor of ammonium nitrate and ammonium sulfates, compounds that are important constituents of airborne fine particulate matter that affect air quality. The characterization of three NH3 CIMS instruments: an atmospheric pressure ionization instrument and a low-pressure flow tube reactor instrument, both utilizing protonated ethanol cluster ion chemistry, and a different low-pressure flow tube reactor instrument using protonated acetone dimer ion chemistry, is presented here. Instrument performance is assessed using ambient data from both ground-based and airborne field programs to examine detection sensitivity, background signal, and time response. Laboratory characterization of different inlet materials is also presented. All three instruments used PFA Teflon sampling inlets. Instrumental backgrounds were determined by scrubbing NH3 from ambient air using silicon phosphates that release phosphoric acid when exposed to ambient levels of humidity. Standard addition calibrations were performed using NH3 permeation devices whose output was determined via 185nm optical absorption. Regardless of CIMS technique or ion chemistry used, the observed detection sensitivities were all adequate for detecting changes in NH3 at the 10 pptv level on a 1s timescale. The time responses, defined by a 1/e2 decay in the calibration signal, ranged from 5s to 45s for the different sampling inlet configurations and are rapid enough

  20. Excitation and Ionisation dynamics in high-frequency plasmas

    NASA Astrophysics Data System (ADS)

    O'Connell, D.

    2008-07-01

    Non-thermal low temperature plasmas are widely used for technological applications. Increased demands on plasma technology have resulted in the development of various discharge concepts based on different power coupling mechanisms. Despite this, power dissipation mechanisms in these discharges are not yet fully understood. Of particular interest are low pressure radio-frequency (rf) discharges. The limited understanding of these discharges is predominantly due to the complexity of the underlying mechanisms and difficult diagnostic access to important parameters. Optical measurements are a powerful diagnostic tool offering high spatial and temporal resolution. Optical emission spectroscopy (OES) provides non-intrusive access, to the physics of the plasma, with comparatively simple experimental requirements. Improved advances in technology and modern diagnostics now allow deeper insight into fundamental mechanisms. In low pressure rf discharges insight into the electron dynamics within the rf cycle can yield vital information. This requires high temporal resolution on a nano-second time scale. The optical emission from rf discharges exhibits temporal variations within the rf cycle. These variations are particularly strong, in for example capacitively coupled plasmas (CCPs), but also easily observable in inductively coupled plasmas (ICPs), and can be exploited for insight into power dissipation. Interesting kinetic and non-linear coupling effects are revealed in capacitive systems. The electron dynamics exhibits a complex spatio-temporal structure. Excitation and ionisation, and, therefore, plasma sustainment is dominated through directed energetic electrons created through the dynamics of the plasma boundary sheath. In the relatively simple case of an asymmetric capacitively coupled rf plasma the complexity of the power dissipation is exposed and various mode transitions can be clearly observed and investigated. At higher pressure secondary electrons dominate the

  1. Gas purge microsyringe extraction for quantitative direct gas chromatographic-mass spectrometric analysis of volatile and semivolatile chemicals.

    PubMed

    Yang, Cui; Piao, Xiangfan; Qiu, Jinxue; Wang, Xiaoping; Ren, Chunyan; Li, Donghao

    2011-03-25

    Sample pretreatment before chromatographic analysis is the most time consuming and error prone part of analytical procedures, yet it is a key factor in the final success of the analysis. A quantitative and fast liquid phase microextraction technique termed as gas purge microsyringe extraction (GP-MSE) has been developed for simultaneous direct gas chromatography-mass spectrometry (GC-MS) analysis of volatile and semivolatile chemicals without cleanup process. Use of a gas flowing system, temperature control and a conventional microsyringe greatly increased the surface area of the liquid phase micro solvent, and led to quantitative recoveries of both volatile and semivolatile chemicals within short extraction time of only 2 min. Recoveries of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and alkylphenols (APs) determined were 85-107%, and reproducibility was between 2.8% and 8.5%. In particular, the technique shows high sensitivity for semivolatile chemicals which is difficult to achieve in other sample pretreatment techniques such as headspace-liquid phase microextraction. The variables affecting extraction efficiency such as gas flow rate, extraction time, extracting solvent type, temperature of sample and extracting solvent were investigated. Finally, the technique was evaluated to determine PAHs, APs and OCPs from plant and soil samples. The experimental results demonstrated that the technique is economic, sensitive to both volatile and semivolatile chemicals, is fast, simple to operate, and allows quantitative extraction. On-site monitoring of volatile and semivolatile chemicals is now possible using this technique due to the simplification and speed of sample treatment.

  2. Imaging of Cells and Tissues with Mass Spectrometry: Adding Chemical Information to Imaging

    PubMed Central

    Zimmerman, Tyler A.; Monroe, Eric B.; Tucker, Kevin R.; Rubakhin, Stanislav S.; Sweedler, Jonathan V.

    2009-01-01

    Techniques that map the distribution of compounds in biological tissues can be invaluable in addressing a number of critical questions in biology and medicine. One of the newest methods, mass spectrometric imaging, has enabled investigation of spatial localization for a variety of compounds ranging from atomics to proteins. The ability of mass spectrometry to detect and differentiate a large number of unlabeled compounds makes the approach amenable to the study of complex biological tissues. This chapter focuses on recent advances in the instrumentation and sample preparation protocols that make mass spectrometric imaging of biological samples possible, including strategies for both tissue and single cell imaging using the following mass spectrometric ionization methods: matrix-assisted laser desorption/ionization, secondary ion, electrospray and desorption electrospray. PMID:19118682

  3. High-throughput chemical residue analysis by fast extraction and dilution flow injection mass spectrometry.

    PubMed

    Nanita, Sergio C

    2011-01-21

    Fast extraction and dilution flow injection mass spectrometry (FED-FI-MS) is presented as a technique to increase throughput in quantitative multiresidue screening in complex matrices, while meeting current analytical method quality requirements.

  4. Chemical Composition of Latent Fingerprints by Gas Chromatography-Mass Spectrometry

    ERIC Educational Resources Information Center

    Hartzell-Baguley, Brittany; Hipp, Rachael E.; Morgan, Neal R.; Morgan, Stephen L.

    2007-01-01

    An experiment in which gas chromatography-mass spectrometry (GC-MS) is used for latent fingerprint extraction and analysis on glass beads or glass slides is conducted. The results determine that the fingerprint residues are gender dependent.

  5. The Chemical Exhaust Hazards of Dichlorosilane Deposits Determined with FT-ICR Mass Spectrometry

    SciTech Connect

    JAREK, RUSSELL L.; THORNBERG, STEVEN M.

    1999-10-01

    Flammable deposits have been analyzed from the exhaust systems of tools employing dichlorosilane (DCS) as a processing gas. Exact mass determinations with a high-resolution Fourier-transform ion-cyclotron resonance (FT-ICR) mass spectrometer allowed the identification of various polysiloxane species present in such an exhaust flow. Ion-molecule reactions indicate the preferred reaction pathway of siloxane formation is through HCl loss, leading to the highly reactive polysiloxane that was detected in the flammable deposits.

  6. Plant seed species identification from chemical fingerprints: a high-throughput application of direct analysis in real time mass spectrometry.

    PubMed

    Lesiak, Ashton D; Cody, Robert B; Dane, A John; Musah, Rabi A

    2015-09-01

    Plant species identification based on the morphological features of plant parts is a well-established science in botany. However, species identification from seeds has largely been unexplored, despite the fact that the seeds contain all of the genetic information that distinguishes one plant from another. Using seeds of genus Datura plants, we show here that the mass spectrum-derived chemical fingerprints for seeds of the same species are similar. On the other hand, seeds from different species within the same genus display distinct chemical signatures, even though they may contain similar characteristic biomarkers. The intraspecies chemical signature similarities on the one hand, and interspecies fingerprint differences on the other, can be processed by multivariate statistical analysis methods to enable rapid species-level identification and differentiation. The chemical fingerprints can be acquired rapidly and in a high-throughput manner by direct analysis in real time mass spectrometry (DART-MS) analysis of the seeds in their native form, without use of a solvent extract. Importantly, knowledge of the identity of the detected molecules is not required for species level identification. However, confirmation of the presence within the seeds of various characteristic tropane and other alkaloids, including atropine, scopolamine, scopoline, tropine, tropinone, and tyramine, was accomplished by comparison of the in-source collision-induced dissociation (CID) fragmentation patterns of authentic standards, to the fragmentation patterns observed in the seeds when analyzed under similar in-source CID conditions. The advantages, applications, and implications of the chemometric processing of DART-MS derived seed chemical signatures for species level identification and differentiation are discussed.

  7. Source apportionment of PM2.5 chemically speciated mass and particle number concentrations in New York City

    NASA Astrophysics Data System (ADS)

    Masiol, M.; Hopke, P. K.; Felton, H. D.; Frank, B. P.; Rattigan, O. V.; Wurth, M. J.; LaDuke, G. H.

    2017-01-01

    The major sources of fine particulate matter (PM2.5) in New York City (NYC) were apportioned by applying positive matrix factorization (PMF) to two different sets of particle characteristics: mass concentrations using chemical speciation data and particle number concentrations (PNC) using number size distribution, continuously monitored gases, and PM2.5 data. Post-processing was applied to the PMF results to: (i) match with meteorological data, (ii) use wind data to detect the likely locations of the local sources, and (iii) use concentration weighted trajectory models to assess the strength of potential regional/transboundary sources. Nine sources of PM2.5 mass were apportioned and identified as: secondary ammonium sulfate, secondary ammonium nitrate, road traffic exhaust, crustal dust, fresh sea-salt, aged sea-salt, biomass burning, residual oil/domestic heating and zinc. The sources of PNC were investigated using hourly average number concentrations in six size bins, gaseous air pollutants, mass concentrations of PM2.5, particulate sulfate, OC, and EC. These data were divided into 3 periods indicative of different seasonal conditions. Five sources were resolved for each period: secondary particles, road traffic, NYC background pollution (traffic and oil heating largely in Manhattan), nucleation and O3-rich aerosol. Although traffic does not account for large amounts of PM2.5 mass, it was the main source of particles advected from heavily trafficked zones. The use of residual oil had limited impacts on PM2.5 mass but dominates PNC in cold periods.

  8. Development of a new ionisation chamber, for HP(10) measurement, using Monte-Carlo simulation and experimental methods.

    PubMed

    Silva, H; Cardoso, J; Oliveira, C

    2011-03-01

    An ionisation chamber that directly measures the quantity personal dose equivalent, H(p)(10), is used as a secondary standard in some metrology laboratories. An ionisation chamber of this type was first developed by Ankerhold. Using the Monte-Carlo simulation, the dose in the sensitive volume as a function of the IC dimensions and the effects of the several components of the ionising chamber have been investigated. Based on these results, a new ionising chamber, lighter than the previous ones, is constructed and experimentally tested.

  9. Spatial and Temporal Variation in Fine Particulate Matter Mass and Chemical Composition: The Middle East Consortium for Aerosol Research Study

    PubMed Central

    Abdeen, Ziad; Heo, Jongbae; Wu, Bo; Shpund, Jacob; Vanger, Arye; Sharf, Geula; Moise, Tamar; Brenner, Shmuel; Nassar, Khaled; Saleh, Rami; Al-Mahasneh, Qusai M.; Sarnat, Jeremy A.; Schauer, James J.

    2014-01-01

    Ambient fine particulate matter (PM2.5) samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM2.5 samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM2.5 across the 11 sites varied from 20.6 to 40.3 μg/m3, with an average of 28.7 μg/m3. Seasonal variation of PM2.5 concentrations was substantial, with higher average concentrations (37.3 μg/m3) in the summer (April–June) months compared to winter (October–December) months (26.0 μg/m3) due mainly to high contributions of sulfate and crustal components. PM2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM2.5 mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM2.5 mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East. PMID:25045751

  10. Spatial and temporal variation in fine particulate matter mass and chemical composition: the Middle East Consortium for Aerosol Research Study.

    PubMed

    Abdeen, Ziad; Qasrawi, Radwan; Heo, Jongbae; Wu, Bo; Shpund, Jacob; Vanger, Arye; Sharf, Geula; Moise, Tamar; Brenner, Shmuel; Nassar, Khaled; Saleh, Rami; Al-Mahasneh, Qusai M; Sarnat, Jeremy A; Schauer, James J

    2014-01-01

    Ambient fine particulate matter (PM2.5) samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM2.5 samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM2.5 across the 11 sites varied from 20.6 to 40.3 μg/m(3), with an average of 28.7 μg/m(3). Seasonal variation of PM2.5 concentrations was substantial, with higher average concentrations (37.3 μg/m(3)) in the summer (April-June) months compared to winter (October-December) months (26.0 μg/m(3)) due mainly to high contributions of sulfate and crustal components. PM2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM2.5 mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM2.5 mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East.

  11. Resonant laser ablation ion trap mass spectrometry -- Recent applications for chemical analysis

    SciTech Connect

    Gill, C.G.; Garrett, A.W.; Hemberger, P.H.; Nogar, N.S.

    1995-12-31

    Resonant Laser Ablation (RLA) is a useful ionization process for selectively producing gas phase ions from a solid sample. Recent use of RLA for mass spectrometry by this group and by others has produced a wealth of knowledge and useful analytical techniques. The method relies upon the focusing of modest intensity laser pulses ({le} 10{sup 7} W {center_dot} Cm{sup {minus}2}) upon a sample surface. A small quantity of material is vaporized, and atoms of desired analyte are subsequently ionized by (n + m) photon processes in the gas phase (where n = number of photons to a resonant transition and m = number of photons to exceed the ionization limit). The authors have been using (2 + 1) resonant ionization schemes for this work. Quadrupole ion trap mass spectrometry is realizing a very prominent role in current mass spectrometric research. Ion traps are versatile, powerful and extremely sensitive mass spectrometers, capable of a variety of ionization modes, MS{sup n} type experiments, high mass ranges and high resolution, all for a fraction of the cost of other instrumentation with similar capabilities. Quadrupole ion traps are ideally suited to pulsed ionization sources such as laser ionization methods, since their normal operational method (Mass Selective Instability) relies upon the storage of ions from a finite ionization period followed by ejection and detection of these ions based upon their mass to charge ratios. The paper describes selective ionization for trace atomic analysis, selective reagent ion source for ion chemistry investigations, and the analysis of ``difficult`` environmental contaminants, i.e., TBP.

  12. Mass Conservation in a Chemical Transport Model and its Effect on CO2 and SF6 Simulations

    NASA Technical Reports Server (NTRS)

    Zhu, Z.; Weaver, C.; Kawa, S. R.; Douglass, A. R.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Chemical transport models (CTMs) must conserve mass to be useful for applications involving assessment of the effect of various pollutants on the troposphere and stratosphere. Furthermore, calculations of the evolution of constituents such as SF6 are used to evaluate overall model transport, and interpretation of such simulations is clouded if mass conservation is not assured. For realistic simulations or predictions, it is crucial that constituents are not produced or lost by transport or other processes in the CTMs. Analysis of CO2 and SF6 experiments using a CTM shows that problems with mass conservation can seriously degrade the simulations. Failure to conserve mass results from inconsistency of the surface pressure tendency and the divergence of horizontal mass flux when the model is forced by assimilated meteorological data. We have developed an effective method to eliminate the inconsistency by modifying the divergent part of the wind field. The changes in the wind fields are quite small but the impact on mass conservation is large. Parameterizations of physical processes such as convection or turbulent transport can also affect mass conservation. The lack of conservation is small but accumulates when integrations are lengthy such as required for SF6. This lack of conservation is found using winds from either a GCM or from an assimilation system. A simple adjustment removes much of the inaccuracy in the convective parameterization. A CO2 simulation using assimilated winds from the most recent version of the Goddard Earth Observing System Data Assimilation System will be used to illustrate the impact of these transport improvements.

  13. Observations of formic and acetic acid by chemical ionization mass spectrometry in the Deep Convective Clouds and Chemistry Experiment

    NASA Astrophysics Data System (ADS)

    Treadaway, V.; McNeill, A.; Heikes, B.; O'Sullivan, D. W.; Silwal, I.

    2013-12-01

    Formic (HFo) and acetic acid (HAc) are part of the atmospheric processing of carbon and their measurement is relevant to defining oxygenated volatile organic carbon (OVOC) emissions, to examining photochemical processing of volatile organic carbon (VOC) and OVOCs, and to the photochemical processing of organic aerosol. Further, they can serve as photochemical tracers of convective transport, cloud chemical processes, and precipitation scavenging. The addition of HFo and HAc measurements to the Deep Convective Clouds and Chemistry Experiment (DC3) is relevant to the DC3 science objectives and complements the suite of chemicals already observed during DC3. The peroxide chemical ionization mass spectrometer (PCIMS) was flown aboard the NCAR Gulfstream-V platform in DC3 and while its primary function was to observe hydrogen peroxide and methylhydroperoxide it recorded signals attributed to iodide cluster ions of HFo and HAc at mass-charge ratios of 173 and 187, respectively. Post-mission laboratory experiments were performed to determine the CIMS instrument's sensitivity to these acids under the varying water vapor and sample flow conditions encountered during DC3 flights. The results of field measurements, laboratory experiments and the HFo and HAc recovery process are reported and HFo and HAc measurement quality assessed. The resultant HFo and HAc data are presented and interpreted with respect to atmospheric chemistry within measurement constraints. The DC3 observations were made in May and June 2012 and extended from the surface to 13 km over the central United States.

  14. Long-term trend of the mass and chemical species' concentrations in PM2.5 at Seoul

    NASA Astrophysics Data System (ADS)

    Han, S.; Kim, Y. P.; Lim, H. J.; Shin, H. J.; Moon, K. J.; Hong, Y. D.; Park, S.

    2015-12-01

    Particulate matter less than or equal to 2.5 μm in aerodynamic diameter (PM2.5) has detrimental effects on human health as well as the environmental effects such as climate change. Thus, understanding trends of the mass concentration and chemical compounds of PM2.5 is needed to establish appropriate policy. The objectives of this study are (1) collecting data and understanding temporal trend of chemical components in PM2.5 at Seoul, and (2) verifying the possible reasons of the trends. The literature data of the mass concentrations of chemical composition of PM2.5, sulfate, nitrate, ammonium, OC (Organic Carbon), and EC (Element Carbon) from 1985 to 2014 at Seoul were collected and their trends were analyzed. The annual concentrations of particulate matters both PM10 and PM2.5 at Seoul have been continuously decreased. The concentrations of ionic component in PM2.5 showed different trends, sulfate decreased during the 1990s but no trend was observed after 2000s while nitrate and ammonium increased during the 2000s. The trend of OC showed no distinctive trend while the EC concentrations decreased.

  15. In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry.

    PubMed

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

    2016-07-01

    We propose detecting a fragment ion (Ph2As(+)) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH(+)) of DA, DC, DPAH, and BDPAO could produce Ph2As(+) through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As(+) signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH(+) signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As(+). Graphical Abstract ᅟ.

  16. In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    We propose detecting a fragment ion (Ph2As+) using counter-flow introduction atmospheric pressure chemical ionization ion trap mass spectrometry for sensitive air monitoring of chemical warfare vomiting agents diphenylchloroarsine (DA) and diphenylcyanoarsine (DC). The liquid sample containing of DA, DC, and bis(diphenylarsine)oxide (BDPAO) was heated in a dry air line, and the generated vapor was mixed into the humidified air flowing through the sampling line of a mass spectrometer. Humidity effect on the air monitoring was investigated by varying the humidity of the analyzed air sample. Evidence of the in-line conversion of DA and DC to diphenylarsine hydroxide (DPAH) and then BDPAO was obtained by comparing the chronograms of various ions from the beginning of heating. Multiple-stage mass spectrometry revealed that the protonated molecule (MH+) of DA, DC, DPAH, and BDPAO could produce Ph2As+ through their in-source fragmentation. Among the signals of the ions that were investigated, the Ph2As+ signal was the most intense and increased to reach a plateau with the increased air humidity, whereas the MH+ signal of DA decreased. It was suggested that DA and DC were converted in-line into BDPAO, which was a major source of Ph2As+.

  17. The chemical evolution of a travertine-depositing stream: geochemical processes and mass transfer reactions

    USGS Publications Warehouse

    Lorah, M.M.; Herman, J.S.

    1988-01-01

    Focuses on quantiatively defining the chemical changes occurring in Falling Spring Creek, a travertine-depositing stream located in Alleghany County, Virgina. The processes of CO2 outgassing and calcite precipitation or dissolution control the chemical evolution of the stream. Physical evidence for calcite precipitation exists in the travertine deposits which are first observed immediately above the waterfall and extend for at least 1.0 km below the falls. Net calcite precipitation occurs at all times of the year but is greatest during low-flow conditions in the summer and early fall. -from Authors

  18. Characterization of Nitrogen-Containing Species in Coal and Petroleum-Derived Products by Ammonia Chemical Ionization-High Resolution Mass Spectrometry

    SciTech Connect

    Veloski, Garret A.; Lynn, Ronald J.; Sprecher, Richard F.

    1997-01-01

    A coal-derived light distillate and a petroleum-derived residuum have been studied by high resolution mass spectrometry using both low-pressure ammonia chemical ionization and low-voltage electron impact ionization. A mass calibration mixture for use with ammonia chemical ionization has been developed. Selective ionization of the basic nitrogen-containing compounds by ammonia chemical ionization and compound type characterization of the resulting quasi-molecular species has been demonstrated. Several homologous series of nitrogen-containing compounds were identified in a basic extract by electron impact ionization and compared with quasimolecular analogs identified by ammonia chemical ionization.

  19. Surface ionisation of molecular H2 and atomic H Rydberg states at doped silicon surfaces

    NASA Astrophysics Data System (ADS)

    Sashikesh, G.; So, E.; Ford, M. S.; Softley, T. P.

    2014-09-01

    The detection of ions or electrons from the surface ionisation of molecular H2 and atomic H Rydberg states incident at doped Si surfaces is investigated experimentally to analyse the effect of the dopant charge distribution on the surface-ionisation processes. In both experimental studies, the molecular H2 and atomic H Rydberg states are generated via two-colour vacuum ultraviolet--ultraviolet (VUV-UV) resonant excitation. For H2, various Stark states of the N+ = 2, n = 17 manifold are populated in the presence of an electric field. The variation of the observed surface-ionisation signal with surface dopant concentration and type, shows similar characteristics for all the Stark states. A comparison is made between these ion-detected surface-ionisation profiles and those obtained via electron detection. Different trends as a function of dopant concentration and type are observed for the two cases, explained by the greater effect of surface charges on the post-ionisation ion trajectory compared to the electron trajectory. For the atomic-H Rydberg states with principal quantum number ? populated in the absence of a Stark field, the observed behaviour is similar to the interaction of molecular H2 Rydberg states at the same surfaces, and these measurements confirm that the observed effects are attributable to the nature of the target surface rather than the specific atomic or molecular Rydberg species.

  20. Ionising irradiation alters the dynamics of human long interspersed nuclear elements 1 (LINE1) retrotransposon.

    PubMed

    Tanaka, Atsushi; Nakatani, Youko; Hamada, Nobuyuki; Jinno-Oue, Atsushi; Shimizu, Nobuaki; Wada, Seiichi; Funayama, Tomoo; Mori, Takahisa; Islam, Salequl; Hoque, Sheikh Ariful; Shinagawa, Masahiko; Ohtsuki, Takahiro; Kobayashi, Yasuhiko; Hoshino, Hiroo

    2012-09-01

    It is important to identify the mechanism by which ionising irradiation induces various genomic alterations in the progeny of surviving cells. Ionising irradiation activates mobile elements like retrotransposons, although the mechanism of its phenomena consisting of transcriptions and insertions of the products into new sites of the genome remains unclear. In this study, we analysed the effects of sparsely ionising X-rays and densely ionising carbon-ion beams on the activities of a family of active retrotransposons, long interspersed nuclear elements 1 (L1). We used the L1/reporter knock-in human glioma cell line, NP-2/L1RP-enhanced GFP (EGFP), that harbours full-length L1 tagged with EGFP retrotransposition detection cassette (L1RP-EGFP) in the chromosomal DNA. X-rays and carbon-ion beams similarly increased frequencies the transcription from L1RP-EGFP and its retrotransposition. Short-sized de novo L1RP-EGFP insertions with 5'-truncation were induced by X-rays, while full-length or long-sized insertions (>5 kb, containing ORF1 and ORF2) were found only in cell clones irradiated by the carbon-ion beams. These data suggest that X-rays and carbon-ion beams induce different length of de novo L1 insertions, respectively. Our findings thus highlight the necessity to investigate the mechanisms of mutations caused by transposable elements by ionising irradiation.

  1. Current issues involving screening and identification of chemical contaminants in foods by mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although quantitative analytical methods must be empirically validated prior to their actual use in a variety of applications, including regulatory monitoring of chemical adulterants in foods, validation of qualitative method performance for the analytes and matrices of interest is frequently ignore...

  2. Rapid Semi-Quantitative Surface Mapping of Airborne-Dispersed Chemicals Using Mass Spectrometry

    EPA Science Inventory

    Chemicals can be dispersed accidentally, deliberately, or by weather-related events. Rapid mapping of contaminant distributions is necessary to assess exposure risks and to plan remediation, when needed. Ten pulverized aspirin or NoDozTM tablets containing caffeine wer...

  3. Ion chemistry of VX surrogates and ion energetics properties of VX: new suggestions for VX chemical ionization mass spectrometry detection.

    PubMed

    Midey, Anthony J; Miller, Thomas M; Viggiano, A A; Bera, Narayan C; Maeda, Satoshi; Morokuma, Keiji

    2010-05-01

    Room temperature rate constants and product ion branching ratios have been measured for the reactions of numerous positive and negative ions with VX chemical warfare agent surrogates representing the amine (triethylamine) and organophosphonate (diethyl methythiomethylphosphonate (DEMTMP)) portions of VX. The measurements have been supplemented by theoretical calculations of the proton affinity, fluoride affinity, and ionization potential of VX and the simulants. The results show that many proton transfer reactions are rapid and that the proton affinity of VX is near the top of the scale. Many proton transfer agents should detect VX selectively and sensitively in chemical ionization mass spectrometers. Charge transfer with NO(+) should also be sensitive and selective since the ionization potential of VX is small. The surrogate studies confirm these trends. Limits of detection for commercial and research grade CIMS instruments are estimated at 80 pptv and 5 ppqv, respectively.

  4. Surface-activated chemical ionization ion trap mass spectrometry in the analysis of amphetamines in diluted urine samples.

    PubMed

    Cristoni, Simone; Bernardi, Luigi Rossi; Gerthoux, Piermario; Gonella, Elisabetta; Mocarelli, Paolo

    2004-01-01

    A new ionization method, named surface-activated chemical ionization (SACI), was employed for the analysis of five amphetamines (3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyethylamphetamine (MDE), amphetamine and methamphetamine) by ion trap mass spectrometry. The results so obtained have been compared with those achieved by using atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) using the same instrument, clearly showing that SACI is the most sensitive of the three. The limit of detection and linearity range for SACI were compared with those obtained using APCI and ESI, showing that the new SACI approach provides the best results for both criteria. SACI was used to analyze MDA, MDMA MDE, amphetamine and methamphetamine in four urine samples, and the quantitation results are compared with those achieved using ESI.

  5. Biodegradation testing of chemicals with high Henry's constants - Separating mass and effective concentration reveals higher rate constants.

    PubMed

    Birch, Heidi; Andersen, Henrik R; Comber, Mike; Mayer, Philipp

    2017-05-01

    During simulation-type biodegradation tests, volatile chemicals will continuously partition between water phase and headspace. This study addressed how (1) this partitioning affects test results and (2) can be accounted for by combining equilibrium partition and dynamic biodegradation models. An aqueous mixture of 9 (semi)volatile chemicals was first generated using passive dosing and then diluted with environmental surface water producing concentrations in the ng/L to μg/L range. After incubation for 2 h to 4 weeks, automated Headspace Solid Phase Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relatively to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Biodegradation rate constants relating to the chemical in the water phase, kwater, were generally a factor 1 to 11 times higher than biodegradation rate constants relating to the total mass of chemical in the test system, ksystem, with one exceptional factor of 72 times for a long chain alkane. True water phase degradation rate constants were found (i) more appropriate for risk assessment than test system rate constants, (ii) to facilitate extrapolation to other air-water systems and (iii) to be better defined input parameters for aquatic exposure and fate models.

  6. Mass spectral reference libraries: an ever-expanding resource for chemical identification.

    PubMed

    Stein, Stephen

    2012-09-04

    The basic principles, practices, and pitfalls in the process of compound identification by searching mass spectral reference libraries are presented. Factors affecting the identification process are discussed as members of one of three major contributors to identification confidence: prior probability, risk of false negative results, and risk of false positive results. More general concerns and the problem of "unknown unknowns" are then explored.

  7. Authentication of organically and conventionally grown basils by gas chromatograpy/mass spectrometry chemical profiles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Basil plants cultivated by organic and conventional farming practices were differentiated using gas chromatography/mass spectrometry (GC/MS) and chemometric methods. The two-way GC/MS data sets were baseline-corrected and retention time-aligned prior to data processing. Two self-devised fuzzy clas...

  8. Absolute method for the assay of oleuropein in olive oils by atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    De Nino, Antonio; Di Donna, Leonardo; Mazzotti, Fabio; Muzzalupo, Enzo; Perri, Enzo; Sindona, Giovanni; Tagarelli, Antonio

    2005-09-15

    Oleuropein (OLP, 1), the active ingredient present (i) in food integrators extracted from olive leaves, (ii) in table olives, and (iii) in extra virgin olive oils is a nutraceutical whose health benefits have been widely documented. A new analytical method for its assay, which is based on the utilization of atmospheric pressure chemical ionization tandem mass spectrometry and on the use of a synthetic labeled analogue, the 4-trideuteriocarboxyoleuropein (2), as an internal standard, is presented. The results obtained with extra virgin olive oils from different cultivars and different Italian regions are discussed.

  9. In situ mass spectroscopic analysis of alcohol catalytic chemical vapor deposition process for single-walled carbon nanotube

    NASA Astrophysics Data System (ADS)

    Tomie, Takashi; Inoue, Shuhei; Iba, Yushi; Matsumura, Yukihiko

    2012-05-01

    In situ mass spectroscopic analysis was carried out to clarify the growth mechanism of single-walled carbon nanotube grown by alcohol catalytic chemical vapor deposition. When catalysts were used, pyrolysis could be accomplished at a temperature of 600 °C; without the use of catalysts, successful pyrolysis required a temperature of more than 800 °C. Ethylene and acetylene are important products for the synthesis of carbon nanotubes, and fusion of the metal catalyst is the cause of failure of synthesis at high temperatures. This fact indicates that the degradation and polymerization of ethanol are not the cause of the failure of synthesis.

  10. Chemical composition and mass size distribution of PM1.0 at an elevated site in central east China

    NASA Astrophysics Data System (ADS)

    Zhang, Y. M.; Zhang, X. Y.; Sun, J. Y.; Hu, G. Y.; Shen, X. J.; Wang, Y. Q.; Wang, T. T.; Wang, D. Z.; Zhao, Y.

    2014-06-01

    Size-resolved aerosol chemical compositions were measured continuously for one and half years with an aerosol mass spectrometer (AMS) to characterize the mass and size distributions (MSDs) of each component in bulk, fresh and aged submicron particles (approximately PM1.0) at Mountain Tai, an elevated site in Central East China (CEC) from June 2010 to January 2012. The majority of the regionally-dispersed aerosols were found to be contributed from short distance mixed aerosol, mostly from its south with organics and sulfate as the major components. The annual mean mass concentrations of organics, sulfate, nitrate, ammonium and chloride were 11.2, 9.2, 7.2, 5.8 and 0.95 μg m-3, respectively, which are much lower for organics and sulfate, and slightly lower for nitrate, ammonium and chloride than those at the nearby surface rural sites. High organics were observed for all four seasons, and the relatively fresh organic aerosol (OA) containing high proportion of less-photo chemically OA, were found from long-range transported aerosol from northwest. Semi-volatile and low-volatile oxidized OAs together contributed approximately 49%, 55% in spring and 72% and 51% in winter of total OA, showing at least 50% of OA can be attributable to SOA. Seasonally, the chemical components at the elevated site showed a "winter high and autumn low" pattern, with organics, sulfate and ammonium peaking in summer. Though no obvious differences of MSDs were seen for various chemical components in the planetary boundary layer (PBL) and free troposphere (FT), the concentrations were a factor of 5-7 higher in PBL than in FT. The averaged MSDs of particles between 30-1000 nm for organics, sulfate, nitrate, and ammonium are approximately log-normal with similar mass median diameters (MMDs) of 539, 585, 542, and 545 nm, respectively, which were slightly larger than those in ground sites within North China Plain (NCP). Obvious differences in MMDs were found between fresh and aged aerosols for

  11. Multidimensional Chemical Modeling of Young Stellar Objects. II. Irradiated Outflow Walls in a High-Mass Star-Forming Region

    NASA Astrophysics Data System (ADS)

    Bruderer, S.; Benz, A. O.; Doty, S. D.; van Dishoeck, E. F.; Bourke, T. L.

    2009-07-01

    Observations of the high-mass star-forming region AFGL 2591 reveal a large abundance of CO+, a molecule known to be enhanced by far-ultraviolet (FUV) and X-ray irradiation. In chemical models assuming a spherically symmetric envelope, the volume of gas irradiated by protostellar FUV radiation is very small due to the high extinction by dust. The abundance of CO+ is thus underpredicted by orders of magnitude. In a more realistic model, FUV photons can escape through an outflow region and irradiate gas at the border to the envelope. Thus, we introduce the first two-dimensional axisymmetric chemical model of the envelope of a high-mass star-forming region to explain the CO+ observations as a prototypical FUV tracer. The model assumes an axisymmetric power-law density structure with a cavity due to the outflow. The local FUV flux is calculated by a Monte Carlo radiative transfer code taking scattering on dust into account. A grid of precalculated chemical abundances, introduced in the first part of this series of papers, is used to quickly interpolate chemical abundances. This approach allows us to calculate the temperature structure of the FUV-heated outflow walls self-consistently with the chemistry. Synthetic maps of the line flux are calculated using a raytracer code. Single-dish and interferometric observations are simulated and the model results are compared to published and new JCMT and Submillimeter Array (SMA) observations. The two-dimensional model of AFGL 2591 is able to reproduce the JCMT single-dish observations and also explains the nondetection by the SMA. We conclude that the observed CO+ line flux and its narrow width can be interpreted by emission from the warm and dense outflow walls irradiated by protostellar FUV radiation.

  12. 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.

  13. Chemical modification of deoxyribonucleic acids: Quantitation of 3-methylthymidine and O4-methylthymidine by tandem mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wood, Joe M.; Hoke, Steven H., II; Graham Cooks, R.; Chae, Whi-Gun; Chang, Ching-Jer

    1991-12-01

    Quantitation of 3-methylthymidine and O4-methylthymidine generated in the reaction of calf thymus DNA with methyl methanesulfonate (MeMS) and 1-methyl-1nitrosourea (MeNU) by mass spectrometry is reported. Quantitative precision of 7% or better is achieved on samples of 10-12 -10-13 mole in the HPLC and a final stage of separation before quantification by tandem mass spectrometry using desorption chemical ionization. Synthetic CD3-labeled nucleosides were used as internal standards for mass spectral quantification. A unique mass spectrometric scanning procedure, which allowed simultaneous MS--MS product ion analysis of both the analyte and the internal standard, was utilized to enchance precision and accuracy in these low level determinations. MeNU (a potent carcinogen) resulted in 18&%; 3-methylation and 0.17% O4-methylation of deoxythymidine whereas MeMS (a weak carcinogen) produced only 6.8% 3-methylation and 0.005% of deoxythymidine. These results demonstrate that the sensitivity and accuracy of this method should be adequate for the detection and quantification of methyl-nucleosides at the sub-picomole level at which mutation is induced in cell cultures.

  14. Facility monitoring of chemical warfare agent simulants in air using an automated, field-deployable, miniature mass spectrometer.

    PubMed

    Smith, Jonell N; Noll, Robert J; Cooks, R Graham

    2011-05-30

    Vapors of four chemical warfare agent (CWA) stimulants, 2-chloroethyl ethyl sulfide (CEES), diethyl malonate (DEM), dimethyl methylphosphonate (DMMP), and methyl salicylate (MeS), were detected, identified, and quantitated using a fully automated, field-deployable, miniature mass spectrometer. Samples were ionized using a glow discharge electron ionization (GDEI) source, and ions were mass analyzed with a cylindrical ion trap (CIT) mass analyzer. A dual-tube thermal desorption system was used to trap compounds on 50:50 Tenax TA/Carboxen 569 sorbent before their thermal release. The sample concentrations ranged from low parts per billion [ppb] to two parts per million [ppm]. Limits of detection (LODs) ranged from 0.26 to 5.0 ppb. Receiver operating characteristic (ROC) curves are presented for each analyte. A sample of CEES at low ppb concentration was combined separately with two interferents, bleach (saturated vapor) and diesel fuel exhaust (1%), as a way to explore the capability of detecting the simulant in an environmental matrix. Also investigated was a mixture of the four CWA simulants (at concentrations in air ranging from 270 to 380 ppb). Tandem mass (MS/MS) spectral data were used to identify and quantify the individual components.

  15. Desorption electrospray ionization-mass spectrometric analysis of low vapor pressure chemical particulates collected from a surface.

    PubMed

    Ewing, K J; Gibson, D; Sanghera, J; Miklos, F

    2015-01-01

    The collection of a low vapor pressure chemical simulant triethyl phosphate sorbed onto silica gel (TEP/SG) from a surface with subsequent analysis of the TEP/SG particulates using desorption electrospray ionization-mass spectrometry (DESI-MS) is described. Collection of TEP/SG particulates on a surface was accomplished using a sticky screen sampler composed of a stainless steel screen coated with partially polymerized polydimethylsiloxane (PDMS). DESI-MS analysis of TEP/SG particulates containing different percentages of TEP sorbed onto silica gel enabled the generation of response curves for the TEP ions m/z 155 and m/z 127. Using the response curves the calculation of the mass of TEP in a 25 wt% sample of TEP/SG was calculated, results show that the calculated mass of TEP was 14% different from the actual mass of TEP in the sample using the m/z 127 TEP ion response curve. Detection limits for the TEP vapor and TEP/SG particulates were calculated to be 4 μg and 6 particles, respectively.

  16. Mass densification and defect restoration in chemical vapor deposition silicon dioxide film using Ar plasma excited by microwave

    SciTech Connect

    Kawase, Kazumasa Motoya, Tsukasa; Uehara, Yasushi; Teramoto, Akinobu; Suwa, Tomoyuki; Ohmi, Tadahiro

    2014-09-01

    Silicon dioxide (SiO{sub 2}) films formed by chemical vapor deposition (CVD) have been treated with Ar plasma excited by microwave. The changes of the mass densities, carrier trap densities, and thicknesses of the CVD-SiO{sub 2} films with the Ar plasma treatments were investigated. The mass density depth profiles were estimated with X-Ray Reflectivity (XRR) analysis using synchrotron radiation. The densities of carrier trap centers due to defects of Si-O bond network were estimated with X-ray Photoelectron Spectroscopy (XPS) time-dependent measurement. The changes of the thicknesses due to the oxidation of Si substrates were estimated with the XRR and XPS. The mass densities of the CVD-SiO{sub 2} films are increased by the Ar plasma treatments. The carrier trap densities of the films are decreased by the treatments. The thicknesses of the films are not changed by the treatments. It has been clarified that the mass densification and defect restoration in the CVD-SiO{sub 2} films are caused by the Ar plasma treatments without the oxidation of the Si substrates.

  17. Effect of 120 keV proton irradiation on mass loss and chemical structure of AG-80 epoxy resin

    NASA Astrophysics Data System (ADS)

    Gao, Yu; Jiang, Sheng-Ling; Dong, Shang-Li; Yang, De-Zhuang

    2010-11-01

    The AG-80 resin is a new type of thermosetting matrix for advanced carbon/epoxy composites. Mass loss effect and the related outgassing are major concerns for its application in space. The changes in mass loss, outgassing and chemical structure under 120 keV proton exposure were investigated for the AG-80 epoxy resin. The variation in chemistry was characterised by X-ray photoelectron spectroscopy. Experimental results show that by increasing the proton fluence, the surface colour of specimens becomes darker. Mass loss ratios ascend remarkably until the fluence of approximately 6.3×1015 cm-2 and then tend to level off. The surface roughness of specimens exhibits an increasing trend followed by a decreasing trend as a function of proton fluence. Under the exposure, the C‒C, C‒H, C‒N and C‒O bonds are broken, a variety of molecule ions with smaller molecular weight are formed and carbon is enriched in the surface layer of the specimens. The changes in mass loss and surface roughness of the AG-80 epoxy resin could be attributed to the formation of the molecule ions and the enrichment of carbon content in the surface layer due to proton radiation.

  18. EPA Method 525.3 - Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS)

    EPA Science Inventory

    Method 525.3 is an analytical method that uses solid phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) for the identification and quantitation of 125 selected semi-volatile organic chemicals in drinking water.

  19. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    SciTech Connect

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-18

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  20. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-01

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22cm diameter and 30cm length, purifies an airflow rate of 5000lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  1. Chemical composition and mass size distribution of PM1 at an elevated site in central east China

    NASA Astrophysics Data System (ADS)

    Zhang, Y. M.; Zhang, X. Y.; Sun, J. Y.; Hu, G. Y.; Shen, X. J.; Wang, Y. Q.; Wang, T. T.; Wang, D. Z.; Zhao, Y.

    2014-11-01

    Size-resolved aerosol chemical compositions were measured continuously for 1.5 years from June 2010 to January 2012 with an aerosol mass spectrometer (AMS) to characterize the mass and size distributions (MSDs) of major chemical components in submicron particles (approximately PM1) at Mountain Tai (Mt. Tai), an elevated site in central east China. The annual mean mass concentrations of organic, sulfate, nitrate, ammonium, and chloride were 11.2, 9.2, 7.2, 5.8, and 0.95 μg m-3, respectively, which are much higher than those at most mountain sites in the USA and Europe, but lower than those at the nearby surface rural sites in China. A clear seasonality was observed for all major components throughout the study, with low concentration in fall and high in summer, and is believed to be caused by seasonal variations in planetary boundary layer (PBL) height, near surface pollutant concentrations and regional transport processes. Air masses were classified into categories impacted by PBL, lower free troposphere (LFT), new particle formation (NPF), in-cloud processes, and polluted aerosols. Organics dominated the PM1 mass during the NPF episodes, while sulfate contributed most to PM1 in cloud events. The average MSDs of particles between 30 and 1000 nm during the entire study for organics, sulfate, nitrate, and ammonium were approximately log-normal with mass median diameters (MMDs) of 539, 585, 542, and 545 nm, respectively. These values are slightly larger than those observed at ground sites within the North China Plain (NCP), likely due to the relative aged and well-mixed aerosol masses at Mt. Tai. There were no obvious differences in MMDs during the PBL, LFT, in-cloud and polluted episodes, but smaller MMDs, especially for organics, were observed during the NPF events. During the PBL, NPF, and polluted episodes, organics accounted for major proportions at smaller modes, and reached 70% at 100-200 nm particles in the polluted events. In cloud episodes, inorganics

  2. Simulation studies on a prototype ionisation chamber for measurement of personal dose equivalent, Hp(10).

    PubMed

    Cardoso, J; Carvalho, A F; Oliveira, C

    2007-01-01

    A prototype ionisation chamber for direct measurement of the personal dose equivalent, Hp(10), similar to the one developed by the Physikalisch-Technische Bundesantalt (PTB), was designed and constructed by the Metrological Laboratory of Ionizing Radiation (LMRI) of Nuclear and Technological Institute (ITN). Tests already performed have shown that the behaviour of this chamber is very similar to the PTB chamber, mainly the energy dependence for the X-ray radiation qualities of the ISO 4037-1 narrow series N-30, N-40, N-60, N-80, N-100 and N-120 and also for gamma radiation of 137Cs and 60Co. However, the results obtained also show a dependence on the energy and angles of incident radiation and a low magnitude of the electrical response of the ionisation chamber. In order to optimise the performance of the chamber, the LMRI initiated numerical simulation of this ionisation chamber by Monte Carlo method using the MCNPX code.

  3. Detection of chemical warfare agent degradation products in foods using liquid chromatography coupled to inductively coupled plasma mass spectrometry and electrospray ionization mass spectrometry.

    PubMed

    Kubachka, Kevin M; Richardson, Douglas D; Heitkemper, Douglas T; Caruso, Joseph A

    2008-08-22

    The following work presents the exploration of three chromatographic separations in combination with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of chemical warfare agent degradation products (CWADPs). The robust ionization of ICP is virtually matrix independent thus enabling the examination of sample matrices generally considered too complicated for analysis by electrospray ionization (ESI) or atmospheric pressure chemical ionization MS with little to no sample preparation. The analysis was focused on detecting CWADPs in food matrices, as they present possible vehicles for terrorist contamination. Due to the specific detection of (31)P by ICP-MS, resolution of analytes of interest from other P-containing interferences (H(3)PO(4)) was a crucial part of each separation. Up to 10 CWADPs were separated in the presence of H(3)PO(4) with detection limits in the low part per billion levels using the methods described. Additionally, one method was tailored to be compatible with both ICP-MS and ESI-MS making structural verification possible.

  4. Chemical and mineralogical analyses of planetary rocks using a laser ablation mass spectrometer for in situ space research

    NASA Astrophysics Data System (ADS)

    Brigitte Neuland, Maike; Mezger, Klaus; Riedo, Andreas; Tulej, Marek; Wurz, Peter

    2015-04-01

    The context chemical analysis is of considerable importance in space research. High resolution in situ studies of planetary materials can yield important information on surface heterogeneity, basic grain mineralogy and chemical composition of surface and subsurface. In turn, these data are the basis for our understanding of the physical and chemical processes which led to the formation and alteration of planetary material [1] [2]. A highly heterogeneous sample of Allende meteorite, representative for extraterrestrial material, is investigated by LMS, a miniature laser ablation mass spectrometer designed for space research [3]. In the current setup a fs-laser ablation ion source is applied, allowing chemical analysis with lateral resolution of about 10-15 μm and sub-micrometre depth resolution [4]. The reflectron TOF mass analyser is used to measure elemental and isotopic composition of the sampled surface. The LMS instrument supports mass resolution 400 and dynamic range of 108 [5]. In the current studies with the fs-ablation ion source significant improvements in the detection efficiency of several metals e.g., Ni, Co, and non-metals e.g., Si, P, S and O, was achieved comparing to our previous setup [6]. Also the values of sensitivity coefficients for these elements are determined to be close to one, which resulted in the substantial improvements of the quantitative element analysis of the sample. Since the ablation crater depth is expected to be about 1 nm/laser shot also the possible changes of the main element or isotope distribution in depth can be analysed to assess their influence on the mineralogical analysis [7]. Several areas on an Allende sample were investigated and the chemical composition across the surface was determined from the mass spectrometric analysis. Also accurate isotope analysis could be conducted for most of main elements with sufficiently high signal to noise ratio. Correlation of elements was conducted and yielded mineralogical maps

  5. Quantitative assessment of chemical artefacts produced by propionylation of histones prior to mass spectrometry analysis.

    PubMed

    Soldi, Monica; Cuomo, Alessandro; Bonaldi, Tiziana

    2016-07-01

    Histone PTMs play a crucial role in regulating chromatin structure and function, with impact on gene expression. MS is nowadays widely applied to study histone PTMs systematically. Because histones are rich in arginine and lysine, classical shot-gun approaches based on trypsin digestion are typically not employed for histone modifications mapping. Instead, different protocols of chemical derivatization of lysines in combination with trypsin have been implemented to obtain "Arg-C like" digestion products that are more suitable for LC-MS/MS analysis. Although widespread, these strategies have been recently described to cause various side reactions that result in chemical modifications prone to be misinterpreted as native histone marks. These artefacts can also interfere with the quantification process, causing errors in histone PTMs profiling. The work of Paternoster V. et al. is a quantitative assessment of methyl-esterification and other side reactions occurring on histones after chemical derivatization of lysines with propionic anhydride [Proteomics 2016, 16, 2059-2063]. The authors estimate the effect of different solvents, incubation times, and pH on the extent of these side reactions. The results collected indicate that the replacement of methanol with isopropanol or ACN not only blocks methyl-esterification, but also significantly reduces other undesired unspecific reactions. Carefully titrating the pH after propionic anhydride addition is another way to keep methyl-esterification under control. Overall, the authors describe a set of experimental conditions that allow reducing the generation of various artefacts during histone propionylation.

  6. Control of Chemical Effects in the Separation Process of a Differential Mobility / Mass Spectrometer System

    PubMed Central

    Schneider, Bradley B.; Coy, Stephen L.; Krylov, Evgeny V.; Nazarov, Erkinjon G.

    2013-01-01

    Differential mobility spectrometry (DMS) separates ions on the basis of the difference in their migration rates under high versus low electric fields. Several models describing the physical nature of this field mobility dependence have been proposed but emerging as a dominant effect is the clusterization model sometimes referred to as the dynamic cluster-decluster model. DMS resolution and peak capacity is strongly influenced by the addition of modifiers which results in the formation and dissociation of clusters. This process increases selectivity due to the unique chemical interactions that occur between an ion and neutral gas phase molecules. It is thus imperative to bring the parameters influencing the chemical interactions under control and find ways to exploit them in order to improve the analytical utility of the device. In this paper we describe three important areas that need consideration in order to stabilize and capitalize on the chemical processes that dominate a DMS separation. The first involves means of controlling the dynamic equilibrium of the clustering reactions with high concentrations of specific reagents. The second area involves a means to deal with the unwanted heterogeneous cluster ion populations emitted from the electrospray ionization process that degrade resolution and sensitivity. The third involves fine control of parameters that affect the fundamental collision processes, temperature and pressure. PMID:20065515

  7. Chemical separation and mass spectrometry of Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial materials using thermal ionization mass spectrometry.

    PubMed

    Yamakawa, Akane; Yamashita, Katsuyuki; Makishima, Akio; Nakamura, Eizo

    2009-12-01

    A sequential chemical separation technique for Cr, Fe, Ni, Zn, and Cu in terrestrial and extraterrestrial silicate rocks was developed for precise and accurate determination of elemental concentration by the isotope dilution method (ID). The technique uses a combination of cation-anion exchange chromatography and Eichrom nickel specific resin. The method was tested using a variety of matrixes including bulk meteorite (Allende), terrestrial peridotite (JP-1), and basalt (JB-1b). Concentrations of each element was determined by thermal ionization mass spectrometry (TIMS) using W filaments and a Si-B-Al type activator for Cr, Fe, Ni, and Zn and a Re filament and silicic acid-H3PO4 activator for Cu. The method can be used to precisely determine the concentrations of these elements in very small silicate samples, including meteorites, geochemical reference samples, and mineral standards for microprobe analysis. Furthermore, the Cr mass spectrometry procedure developed in this study can be extended to determine the isotopic ratios of 53Cr/52Cr and 54Cr/52Cr with precision of approximately 0.05epsilon and approximately 0.10epsilon (1epsilon = 0.01%), respectively, enabling cosmochemical applications such as high precision Mn-Cr chronology and investigation of nucleosynthetic isotopic anomalies in meteorites.

  8. Perceiving the chemical language of Gram-negative bacteria: listening by high-resolution mass spectrometry.

    PubMed

    Cataldi, Tommaso R I; Bianco, Giuliana; Fonseca, Juliano; Schmitt-Kopplin, Philippe

    2013-01-01

    Gram-negative bacteria use N-acylhomoserine lactones (AHLs) as their command language to coordinate population behavior during invasion and colonization of higher organisms. Although many different bacterial bioreporters are available for AHLs monitoring, in which a phenotypic response, e.g. bioluminescence, violacin production, and β-galactosidase activity, is exploited, mass spectrometry (MS) is the most versatile detector for rapid analysis of AHLs in complex microbial samples, with or without prior separation steps. In this paper we critically review recent advances in the application of high-resolution MS to analysis of the quorum sensing (QS) signaling molecules used by Gram-negative bacteria, with much emphasis on AHLs. A critical review of the use of bioreporters in the study of AHLs is followed by a short methodological survey of the capabilities of high-resolution mass spectrometry (HRMS), including Fourier-transform ion cyclotron resonance (FTICR) MS and quadrupole time-of-flight (qTOF) MS. Use of infusion electrospray ultrahigh-resolution FTICR MS (12 Tesla) enables accurate mass measurements for determination of the elemental formulas of AHLs in Acidovorax sp. N35 and Burkholderia ubonensis AB030584. Results obtained by coupling liquid chromatography with a hybrid quadrupole linear ion trap-FTICR mass spectrometer (LC-LTQ-FTICRMS, 7-T) for characterization of acylated homoserine lactones in the human pathogen Pseudomonas aeruginosa are presented. UPLC-ESI-qTOF MS has also proved to be suitable for identification of 3O-C(10)HSL in Pseudomonas putida IsoF cell culture supernatant. Aspects of sample preparation and the avoidance of analytical pitfalls are also emphasized.

  9. Investigation of Chemical Reactivity, Mass Recovery and Biological Activity During Thermal Treatment of DNAPL Source Zones

    DTIC Science & Technology

    2009-10-01

    passive remediation ERH electrical resistive heating Fe iron Fe2+ ferrous iron Fe3+ ferric iron FeOOH iron oxide mineral FeS2 pyrite ...Silica Co. Laboratory in Berkeley Springs, WV for X-ray diffraction (XRD) analysis. The mineral phases identified in the sand included pyrite ...marcasite (FeS2 - polymorph of pyrite ), and hematite (Fe2O3). The Ottawa sand was also analyzed for 20 elements using inductively coupled plasma mass

  10. Mass transfer constraints on the chemical evolution of an active hydrothermal system, Valles caldera, New Mexico

    USGS Publications Warehouse

    White, A.F.; Chuma, N.J.; Goff, F.

    1992-01-01

    Partial equilibrium conditions occur between fluids and secondary minerals in the Valles hydrothermal system, contained principally in the Tertiary rhyolitic Bandelier Tuff. The mass transfer processes are governed by reactive phase compositions, surface areas, water-rock ratios, reaction rates, and fluid residence times. Experimental dissolution of the vitric phase of the tuff was congruent with respect to Cl in the solid and produced reaction rates which obeyed a general Arrhenius release rate between 250 and 300??C. The 18O differences between reacted and unreacted rock and fluids, and mass balances calculations involving Cl in the glass phase, produced comparable water-rock ratios of unity, confirming the importance of irreversible reaction of the vitric tuff. A fluid residence time of approximately 2 ?? 103 years, determined from fluid reservoir volume and discharge rates, is less than 0.2% of the total age of the hydrothermal system and denotes a geochemically and isotopically open system. Mass transfer calculations generally replicated observed reservoir pH, Pco2, and PO2 conditions, cation concentrations, and the secondary mineral assemblage between 250 and 300??C. The only extraneous component required to maintain observed calcite saturation and high Pco2 pressures was carbon presumably derived from underlying Paleozoic limestones. Phase rule constraints indicate that Cl was the only incompatible aqueous component not controlled by mineral equilibrium. Concentrations of Cl in the reservoir directly reflect mass transport rates as evidenced by correlations between anomalously high Cl concentrations in the fluids and tuff in the Valles caldera relative to other hydrothermal systems in rhyolitic rocks. ?? 1992.

  11. Portable gas chromatograph mass spectrometer for on-site chemical analyses

    DOEpatents

    Haas, Jeffrey S.; Bushman, John F.; Howard, Douglas E.; Wong, James L.; Eckels, Joel D.

    2002-01-01

    A portable, lightweight (approximately 25 kg) gas chromatograph mass spectrometer, including the entire vacuum system, can perform qualitative and quantitative analyses of all sample types in the field. The GC/MS has a conveniently configured layout of components for ease of serviceability and maintenance. The GC/MS system can be transported under operating or near-operating conditions (i.e., under vacuum and at elevated temperature) to reduce the downtime before samples can be analyzed on-site.

  12. The Vertical Structure of Warm Ionised Gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Gaensler, B. M.; Madsen, G. J.; Chatterjee, S.; Mao, S. A.

    2008-11-01

    We present a new joint analysis of pulsar dispersion measures and diffuse Hα emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by Hii regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830-250+120 pc, a factor of two larger than has been derived in previous studies. The corresponding inconsistent scale heights for dispersion measure and emission measure imply that the vertical profiles of mass and pressure in the WIM are decoupled, and that the filling factor of WIM clouds is a geometric response to the competing environmental influences of thermal and non-thermal processes. Extrapolating the properties of the thick-disk WIM to mid-plane, we infer a volume-averaged electron density 0.014 +/- 0.001 cm-3, produced by clouds of typical electron density 0.34 +/- 0.06 cm-3 with a volume filling factor 0.04 +/- 0.01. As one moves off the plane, the filling factor increases to a maximum of ~30% at a height of ~1-1.5 kpc, before then declining to accommodate the increasing presence of hot, coronal gas. Since models for the WIM with a ~1 kpc scale-height have been widely used to estimate distances to radio pulsars, our revised parameters suggest that the distances to many high-latitude pulsars have been substantially underestimated.

  13. Chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of uranium hexafluoride

    SciTech Connect

    Not Available

    1981-01-01

    Analytical procedures, which are in routine use to determine conformance to uranium hexafluoride (UF/sub 6/) specifications in the Department of Energy gaseous diffusion plants or at other installations, are described in detail. Included are: subsampling of UF/sub 6/; gravimetric determination of uranium; titrimetric determination of uranium and of chlorine; preparation of high-purity U/sub 3/O/sub 8/; isotopic analysis by double-standard and by single-standard mass-spectrometer method; determination of hydrocarbons, chlorocarbons, and partially substituted halohydrocarbons; atomic absorption determination of antimony, ruthenium, and metallic impurities; spectrophotometric determination of bromine, silicon and phosphorus, titanium and vanadium, tungsten, thorium, and molybdenum; spectrographic determination of boron and silicon, ruthenium, thorium and rare earths; spectrographic determination of metallic impurities by carrier distillation; spectrographic determination of hafnium, molybdenum, niobium, tantalum, titanium, tungsten, vanadium, and zirconium after separation from UF/sub 6/ with BPHA and as cupferrides; impurity determination by spark-source mass spectrography; determination of boron-equivalent neutron cross section; determination of uranium-233 abundance by thermal ionization mass spectrometry; determination of uranium-232 by alpha spectrometry; determination of fission product activity by beta and gamma counting; determination of plutonium by ion exchange and alpha counting;determination of technetium-99 in UF/sub 6/; determination of gamma-energy emission rate from fission products in UF/sub 6/; determination of plutonium and neptunium by extraction and alpha counting; atomic absorption determination of chromium soluble and insoluble in UF/sub 6/. (JMT)

  14. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    NASA Astrophysics Data System (ADS)

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-07-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  15. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    DOE PAGES

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; ...

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguishmore » between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.« less

  16. High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    SciTech Connect

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijhout, Falko P.

    2015-07-09

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. Moreover, a range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. In this paper, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required.

  17. A High Throughput Ambient Mass Spectrometric Approach to Species Identification and Classification from Chemical Fingerprint Signatures

    PubMed Central

    Musah, Rabi A.; Espinoza, Edgard O.; Cody, Robert B.; Lesiak, Ashton D.; Christensen, Earl D.; Moore, Hannah E.; Maleknia, Simin; Drijfhout, Falko P.

    2015-01-01

    A high throughput method for species identification and classification through chemometric processing of direct analysis in real time (DART) mass spectrometry-derived fingerprint signatures has been developed. The method entails introduction of samples to the open air space between the DART ion source and the mass spectrometer inlet, with the entire observed mass spectral fingerprint subjected to unsupervised hierarchical clustering processing. A range of both polar and non-polar chemotypes are instantaneously detected. The result is identification and species level classification based on the entire DART-MS spectrum. Here, we illustrate how the method can be used to: (1) distinguish between endangered woods regulated by the Convention for the International Trade of Endangered Flora and Fauna (CITES) treaty; (2) assess the origin and by extension the properties of biodiesel feedstocks; (3) determine insect species from analysis of puparial casings; (4) distinguish between psychoactive plants products; and (5) differentiate between Eucalyptus species. An advantage of the hierarchical clustering approach to processing of the DART-MS derived fingerprint is that it shows both similarities and differences between species based on their chemotypes. Furthermore, full knowledge of the identities of the constituents contained within the small molecule profile of analyzed samples is not required. PMID:26156000

  18. Identification of substances migrating from plastic baby bottles using a combination of low-resolution and high-resolution mass spectrometric analysers coupled to gas and liquid chromatography.

    PubMed

    Onghena, Matthias; Van Hoeck, Els; Van Loco, Joris; Ibáñez, María; Cherta, Laura; Portolés, Tania; Pitarch, Elena; Hernandéz, Félix; Lemière, Filip; Covaci, Adrian

    2015-11-01

    This work presents a strategy for elucidation of unknown migrants from plastic food contact materials (baby bottles) using a combination of analytical techniques in an untargeted approach. First, gas chromatography (GC) coupled to mass spectrometry (MS) in electron ionisation mode was used to identify migrants through spectral library matching. When no acceptable match was obtained, a second analysis by GC-(electron ionisation) high resolution mass spectrometry time of flight (TOF) was applied to obtain accurate mass fragmentation spectra and isotopic patterns. Databases were then searched to find a possible elemental composition for the unknown compounds. Finally, a GC hybrid quadrupole-TOF-MS with an atmospheric pressure chemical ionisation source was used to obtain the molecular ion or the protonated molecule. Accurate mass data also provided additional information on the fragmentation behaviour as two acquisition functions with different collision energies were available (MS(E) approach). In the low-energy function, limited fragmentation took place, whereas for the high-energy function, fragmentation was enhanced. For less volatile unknowns, ultra-high pressure liquid chromatography-quadrupole-TOF-MS was additionally applied. Using a home-made database containing common migrating compounds and plastic additives, tentative identification was made for several positive findings based on accurate mass of the (de)protonated molecule, product ion fragments and characteristic isotopic ions. Six illustrative examples are shown to demonstrate the modus operandi and the difficulties encountered during identification. The combination of these techniques was proven to be a powerful tool for the elucidation of unknown migrating compounds from plastic baby bottles.

  19. Atmospheric-pressure chemical ionization tandem mass spectrometry (APGC/MS/MS) an alternative to high-resolution mass spectrometry (HRGC/HRMS) for the determination of dioxins.

    PubMed

    van Bavel, Bert; Geng, Dawei; Cherta, Laura; Nácher-Mestre, Jaime; Portolés, Tania; Ábalos, Manuela; Sauló, Jordi; Abad, Esteban; Dunstan, Jody; Jones, Rhys; Kotz, Alexander; Winterhalter, Helmut; Malisch, Rainer; Traag, Wim; Hagberg, Jessika; Ericson Jogsten, Ingrid; Beltran, Joaquim; Hernández, Félix

    2015-09-01

    The use of a new atmospheric-pressure chemical ionization source for gas chromatography (APGC) coupled with a tandem quadrupole mass spectrometry (MS/MS) system, as an alternative to high-resolution mass spectrometry (HRMS), for the determination of PCDDs/PCDFs is described. The potential of using atmospheric-pressure chemical ionization (APCI) coupled to a tandem quadrupole analyzer has been validated for the identification and quantification of dioxins and furans in different complex matrices. The main advantage of using the APCI source is the soft ionization at atmospheric pressure, which results in very limited fragmentation. APCI mass spectra are dominated by the molecular ion cluster, in contrast with the high energy ionization process under electron ionization (EI). The use of the molecular ion as the precursor ion in MS/MS enhances selectivity and, consequently, sensitivity by increasing the signal-to-noise ratios (S/N). For standard solutions of 2,3,7,8-TCDD, injections of 10 fg in the splitless mode on 30- or 60-m-length, 0.25 mm inner diameter (id), and 25 μm film thickness low-polarity capillary columns (DB5MS type), signal-to-noise (S/N) ratios of >10:1 were routinely obtained. Linearity was achieved in the region (correlation coefficient of r(2) > 0.998) for calibration curves ranging from 100 fg/μL to 1000 pg/μL. The results from a wide variety of complex samples, including certified and standard reference materials and samples from several QA/QC studies, which were previously analyzed by EI HRGC/HRMS, were compared with the results from the APGC/MS/MS system. Results between instruments showed good agreement both in individual congeners and toxic equivalence factors (TEQs). The data show that the use of APGC in combination with MS/MS for the analysis of dioxins has the same potential, in terms of sensitivity and selectivity, as the traditional HRMS instrumentation used for this analysis. However, the APCI/MS/MS system, as a benchtop system, is

  20. Topographical and Chemical Imaging of a Phase Separated Polymer Using a Combined Atomic Force Microscopy/Infrared Spectroscopy/Mass Spectrometry Platform.

    PubMed

    Tai, Tamin; Karácsony, Orsolya; Bocharova, Vera; Van Berkel, Gary J; Kertesz, Vilmos

    2016-03-01

    In this paper, the use of a hybrid atomic force microscopy/infrared spectroscopy/mass spectrometry imaging platform was demonstrated for the acquisition and correlation of nanoscale sample surface topography and chemical images based on infrared spectroscopy and mass spectrometry. The infrared chemical imaging component of the system utilized photothermal expansion of the sample at the tip of the atomic force microscopy probe recorded at infrared wave numbers specific to the different surface constituents. The mass spectrometry-based chemical imaging component of the system utilized nanothermal analysis probes for thermolytic surface sampling followed by atmospheric pressure chemical ionization of the gas phase species produced with subsequent mass analysis. The basic instrumental setup, operation, and image correlation procedures are discussed, and the multimodal imaging capability and utility are demonstrated using a phase separated poly(2-vinylpyridine)/poly(methyl methacrylate) polymer thin film. The topography and both the infrared and mass spectral chemical images showed that the valley regions of the thin film surface were comprised primarily of poly(2-vinylpyridine) and hill or plateau regions were primarily poly(methyl methacrylate). The spatial resolution of the mass spectral chemical images was estimated to be 1.6 μm based on the ability to distinguish surface features in those images that were also observed in the topography and infrared images of the same surface.

  1. Molybdic acid ionisation under hydrothermal conditions to 300 °C

    NASA Astrophysics Data System (ADS)

    Minubayeva, Z.; Seward, T. M.

    2010-08-01

    This UV spectrophotometric study was aimed at providing precise, experimentally derived thermodynamic data for the ionisation of molybdic acid (H 2MoO 4) from 30 to 300 °C and at equilibrium saturated vapour pressures. The determination of the equilibrium constants and associated thermodynamic parameters were facilitated by spectrophotometric measurements using a specially designed high temperature optical Ti-Pd flow-through cell with silica glass windows. The following van't Hoff isochore equations describe the temperature dependence of the first and second ionisation constants of molybdic acid up to 300 °C:

  2. A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry.

    PubMed

    Murawski, Ł; Zielczyński, M; Golnik, N; Gryziński, M A

    2014-10-01

    A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge.

  3. New method for comprehensive detection of chemical warfare agents using an electron-cyclotron-resonance ion-source mass spectrometer.

    PubMed

    Kidera, Masanori; Seto, Yasuo; Takahashi, Kazuya; Enomoto, Shuichi; Kishi, Shintaro; Makita, Mika; Nagamatsu, Tsuyoshi; Tanaka, Tatsuhiko; Toda, Masayoshi

    2011-03-01

    We developed a detection technology for vapor forms of chemical warfare agents (CWAs) with an element analysis system using an electron cyclotron resonance ion source. After the vapor sample was introduced directly into the ion source, the molecular material was decomposed into elements using electron cyclotron resonance plasma and ionized. The following CWAs and stimulants were examined: diisopropyl fluorophosphonate (DFP), 2-chloroethylethylsulfide (2CEES), cyanogen chloride (CNCl), and hydrogen cyanide (HCN). The type of chemical warfare agents, specifically, whether it was a nerve agent, blister agent, blood agent, or choking agent, could be determined by measuring the quantities of the monatomic ions or CN(+) using mass spectrometry. It was possible to detect gaseous CWAs that could not be detected by a conventional mass spectrometer. The distribution of electron temperature in the plasma could be closely controlled by adjusting the input power of the microwaves used to generate the electron cyclotron resonance plasma, and the target compounds could be detected as molecular ions or fragment ions, enabling identification of the target agents.

  4. New method for comprehensive detection of chemical warfare agents using an electron-cyclotron-resonance ion-source mass spectrometer

    NASA Astrophysics Data System (ADS)

    Kidera, Masanori; Seto, Yasuo; Takahashi, Kazuya; Enomoto, Shuichi; Kishi, Shintaro; Makita, Mika; Nagamatsu, Tsuyoshi; Tanaka, Tatsuhiko; Toda, Masayoshi

    2011-03-01

    We developed a detection technology for vapor forms of chemical warfare agents (CWAs) with an element analysis system using an electron cyclotron resonance ion source. After the vapor sample was introduced directly into the ion source, the molecular material was decomposed into elements using electron cyclotron resonance plasma and ionized. The following CWAs and stimulants were examined: diisopropyl fluorophosphonate (DFP), 2-chloroethylethylsulfide (2CEES), cyanogen chloride (CNCl), and hydrogen cyanide (HCN). The type of chemical warfare agents, specifically, whether it was a nerve agent, blister agent, blood agent, or choking agent, could be determined by measuring the quantities of the monatomic ions or CN + using mass spectrometry. It was possible to detect gaseous CWAs that could not be detected by a conventional mass spectrometer. The distribution of electron temperature in the plasma could be closely controlled by adjusting the input power of the microwaves used to generate the electron cyclotron resonance plasma, and the target compounds could be detected as molecular ions or fragment ions, enabling identification of the target agents.

  5. Multivariate Statistical Analysis of Orthogonal Mass Spectral Data for the Identification of Chemical Attribution Signatures of 3-Methylfentanyl

    SciTech Connect

    Mayer, B. P.; Valdez, C. A.; DeHope, A. J.; Spackman, P. E.; Sanner, R. D.; Martinez, H. P.; Williams, A. M.

    2016-11-28

    Critical to many modern forensic investigations is the chemical attribution of the origin of an illegal drug. This process greatly relies on identification of compounds indicative of its clandestine or commercial production. The results of these studies can yield detailed information on method of manufacture, sophistication of the synthesis operation, starting material source, and final product. In the present work, chemical attribution signatures (CAS) associated with the synthesis of the analgesic 3- methylfentanyl, N-(3-methyl-1-phenethylpiperidin-4-yl)-N-phenylpropanamide, were investigated. Six synthesis methods were studied in an effort to identify and classify route-specific signatures. These methods were chosen to minimize the use of scheduled precursors, complicated laboratory equipment, number of overall steps, and demanding reaction conditions. Using gas and liquid chromatographies combined with mass spectrometric methods (GC-QTOF and LC-QTOF) in conjunction with inductivelycoupled plasma mass spectrometry (ICP-MS), over 240 distinct compounds and elements were monitored. As seen in our previous work with CAS of fentanyl synthesis the complexity of the resultant data matrix necessitated the use of multivariate statistical analysis. Using partial least squares discriminant analysis (PLS-DA), 62 statistically significant, route-specific CAS were identified. Statistical classification models using a variety of machine learning techniques were then developed with the ability to predict the method of 3-methylfentanyl synthesis from three blind crude samples generated by synthetic chemists without prior experience with these methods.

  6. Approach toward minimizing chemical interference in FAB mass spectra: the development and application of thermally - assisted FAB

    SciTech Connect

    Ackermann, B.L.

    1987-01-01

    Interferences with fast atom bombardment (FAB) mass spectrometry can be classified into two major categories. The first includes impurities which remain after analyte isolation/purification, and is especially problematic in samples of biological origin. The second type of chemical interference originates from the matrix used for FAB. An example of the first type, also known as sample-related interference, is presented in the context of the analysis of the urinary metabolites of the analgesic acetaminophen by means of the off-line combination of reverse phase HPLC and FAB. Recommendations are made for efficient use of these two methods with specific regard to minimizing chemical interferences. In addition, a method for calculating analyte signal to background (S/B) values is introduced as a means of evaluating the quality of the FAB mass spectrum. A method known as thermally-assisted FAB (TA-FAB) is introduced as a means of minimizing matrix-related background. Success to date has been achieved using aqueous saccharide solutions as TA-FAB matrices. Several important improvements to FAB result from thermal control of the matrix including a selection against matrix background, and the possibility of valid background subtraction. The development of TA-FAB is described in the context of applications of the technique to the analysis of several representative nonvolatile biomolecules including a series of cyclic tetrapeptide mycotoxins. In the final section, the hypothesis of ternary perculation (TP) is submitted to account for behavior observed during TA-FAB.

  7. An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.

    PubMed

    Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

    2015-07-01

    Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt.

  8. Metabolomics relative quantitation with mass spectrometry using chemical derivatization and isotope labeling

    DOE PAGES

    O'Maille, Grace; Go, Eden P.; Hoang, Linh; ...

    2008-01-01

    Comprehensive detection and quantitation of metabolites from a biological source constitute the major challenges of current metabolomics research. Two chemical derivatization methodologies, butylation and amination, were applied to human serum for ionization enhancement of a broad spectrum of metabolite classes, including steroids and amino acids. LC-ESI-MS analysis of the derivatized serum samples provided a significant signal elevation across the total ion chromatogram to over a 100-fold increase in ionization efficiency. It was also demonstrated that derivatization combined with isotopically labeled reagents facilitated the relative quantitation of derivatized metabolites from individual as well as pooled samples.

  9. Aerosol mass spectrometer for the in situ analysis of chemical vapor synthesis processes in hot wall reactors

    NASA Astrophysics Data System (ADS)

    Lee, In-Kyum; Winterer, Markus

    2005-09-01

    We present a modified aerosol mass spectrometer (AMS) for the in situ analysis of chemical vapor synthesis processes in hot wall reactors and describe the transfer function of the velocity and kinetic-energy measurement. The AMS is a combination of a quadrupole mass spectrometer (QMS) and a particle mass spectrometer (PMS) and enables the in situ analysis of aerosols with high number concentrations up to 1018m-3. Size distributions of ultrafine particles in the range of 104-107u (amu) can be measured in the PMS. Simultaneously, molecular species up to 300u can be detected in the QMS. In the setup described here a furnace was developed to enable measurement directly at the reactor exit. The formation of silicon carbide (SiC) nanoparticles by thermal decomposition of tetramethylsilane (TMS) was investigated. TMS started to decompose at about 900K and carbosilanes with two [-Si-C-] units were identified as growth species in the synthesis of SiC from TMS. With increasing temperatures particles were formed and grew by coagulation. At higher temperatures sintering of the particles became an important process. Although the particle mass reduced slightly due to a smaller residence time at higher temperatures in the reactor, the particle velocity in the molecular beam of the AMS decreased significantly. A simple model is used to compare the particle velocity in a molecular beam as a function of particle mass. The significant difference in the particle velocity can be explained by a change in the particle shape factor (κp) due to sintering.

  10. Chemical or Biological Terrorist Attacks: An Analysis of the Preparedness of Hospitals for Managing Victims Affected by Chemical or Biological Weapons of Mass Destruction

    PubMed Central

    Bennett, Russell L.

    2006-01-01

    The possibility of a terrorist attack employing the use of chemical or biological weapons of mass destruction (WMD) on American soil is no longer an empty threat, it has become a reality. A WMD is defined as any weapon with the capacity to inflict death and destruction on such a massive scale that its very presence in the hands of hostile forces is a grievous threat. Events of the past few years including the bombing of the World Trade Center in 1993, the Murrah Federal Building in Oklahoma City in 1995 and the use of planes as guided missiles directed into the Pentagon and New York’s Twin Towers in 2001 (9/11) and the tragic incidents involving twenty-three people who were infected and five who died as a result of contact with anthrax-laced mail in the Fall of 2001, have well established that the United States can be attacked by both domestic and international terrorists without warning or provocation. In light of these actions, hospitals have been working vigorously to ensure that they would be “ready” in the event of another terrorist attack to provide appropriate medical care to victims. However, according to a recent United States General Accounting Office (GAO) nationwide survey, our nation’s hospitals still are not prepared to manage mass causalities resulting from chemical or biological WMD. Therefore, there is a clear need for information about current hospital preparedness in order to provide a foundation for systematic planning and broader discussions about relative cost, probable effectiveness, environmental impact and overall societal priorities. Hence, the aim of this research was to examine the current preparedness of hospitals in the State of Mississippi to manage victims of terrorist attacks involving chemical or biological WMD. All acute care hospitals in the State were selected for inclusion in this study. Both quantitative and qualitative methods were utilized for data collection and analysis. Six hypotheses were tested. Using a

  11. Chemical recoveries of technetium-99 for various procedures using inductively coupled plasma-mass spectrometry

    SciTech Connect

    Ihsanullah; East, B.W.

    1993-12-31

    The procedure for the determination of {sup 99}Tc inductively coupled plasma-mass spectrometry (ICP-MS) was based on the modification of a variety of available separation techniques. Standard Ru and Rh solutions were used for checking decontaminations and instrument response respectively. Technetium-99 and {sup 95m}Tc tracers were applied as yield monitors using ICP-MS and gamma-ray spectrometry respectively. Percent recoveries are reported for a variety of radiochemical separation procedures for water (58-83%), seaweed (10-76%), and for soil matrices (19-79%).

  12. Topographical and Chemical Imaging of a Phase Separated Polymer Using a Combined Atomic Force Microscopy/Infrared Spectroscopy/Mass Spectrometry Platform

    SciTech Connect

    Tai, Tamin; Karácsony, Orsolya; Bocharova, Vera; Van Berkel, Gary J.; Kertesz, Vilmos

    2016-02-18

    This article describes how the use of a hybrid atomic force microscopy/infrared spectroscopy/mass spectrometry imaging platform was demonstrated for the acquisition and correlation of nanoscale sample surface topography and chemical images based on infrared spectroscopy and mass spectrometry.

  13. Chemical characterization of bio-oils using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

    PubMed

    Tessarolo, Nathalia S; dos Santos, Luciana R M; Silva, Raphael S F; Azevedo, Débora A

    2013-03-01

    The liquid product obtained via the biomass flash pyrolysis is commonly called bio-oil or pyrolysis oil. Bio-oils can be used as sources for chemicals or as fuels, primarily in mixtures or emulsions with fossil fuels. A detailed chemical characterization of bio-oil is necessary to determine its potential uses. Such characterization demands a powerful analytical technique such as comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). Limited chemical information can be obtained from conventional gas chromatography coupled mass spectrometry (GC-MS) because of the large number of compounds and coelutions. Thus, GC×GC-TOFMS was used for the individual identification of bio-oil components from two samples prepared via the flash pyrolysis of empty palm fruit bunch and pine wood chips. To the best of our knowledge, few papers have reported comprehensive two-dimensional gas chromatography (GC×GC) for bio-oil analysis. Many classes of compounds such as phenols, benzenediols, cyclopentenones, furanones, indanones and alkylpyridines were identified. Several coelutions present in the GC-MS were resolved using GC×GC-TOFMS. Many peaks were detected for the samples by GC-MS (~166 and 129), but 631 and 857 were detected by GC×GC-TOFMS, respectively. The GC×GC-TOFMS analyses indicated that the major classes of components (analytes>0.5% relative area) in the two bio-oil samples are ketones, cyclopentenones, furanones, furans, phenols, benzenediols, methoxy- and dimethoxy-phenols and sugars. In addition, esters, aldehydes and pyridines were found for sample obtained from empty palm fruit bunch, while alcohols and cyclopentanediones were found in sample prepared from pine wood chips indicating different composition profiles due to the biomass sources. The elucidation of the composition of empty fruit bunch and pine wood chips bio-oils indicates that these oils are suitable for the production of value-added chemicals. The

  14. The Chemistry of High Mass Star Forming Regions with ''Chemical Differentiation'': Orion KL, W75N, & W3

    NASA Astrophysics Data System (ADS)

    Friedel, D. N.; Widicus Weaver, S.

    2011-05-01

    Orion-KL, one of the closest regions of massive star-formation, displays the most well-defined case of ''chemical differentiation'' in interstellar clouds. Here, the emission signatures for oxygen- and nitrogen-bearing organic molecules are spatially distinct. Using CARMA, we have conducted λ=3 mm imaging studies of Orion at beam sizes ranging from 5''-0.5''. These observations are at higher spatial resolution than any previously reported, revealing the relative location of these molecules within the region to high precision, and indicating whether their emission is coincident with continuum sources, shocks, or other energy sources within the Orion-KL complex. These observations targeted transitions of ethyl cyanide [C_2H_5CN], dimethyl ether [(CH_3)_2O], methyl formate [HCOOCH_3], formic acid [HCOOH], acetone [(CH_3)_2CO], and methanol [CH_3OH]. We will present the results of these observations, and discuss the implications of these results on the formation and destruction mechanisms for large organic molecules in star-forming regions. Additionally, we have conducted similar observations of two other high mass star forming regions, that also show signs of ''chemical differentiation'': W75N and W3. These observations were to determine if the results found in Orion were unique or more common across sources that show ''chemical differentiation''. The results of these observations will also be presented.

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

    PubMed

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

    2014-05-01

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

  16. Chemical dereplication of marine actinomycetes by liquid chromatography-high resolution mass spectrometry profiling and statistical analysis.

    PubMed

    Forner, David; Berrué, Fabrice; Correa, Hebelin; Duncan, Katherine; Kerr, Russell G

    2013-12-17

    Discovery of novel bioactive metabolites from marine bacteria is becoming increasingly challenging, and the development of novel approaches to improve the efficiency of early steps in the microbial drug discovery process is therefore of interest. For example, current protocols for the taxonomic dereplication of microbial strains generally use molecular tools which do not take into consideration the ability of these selected bacteria to produce secondary metabolites. As the identification of novel chemical entities is one of the key elements driving drug discovery programs, this study reports a novel methodology to dereplicate microbial strains by a metabolomics approach using liquid chromatography-high resolution mass spectrometry (LC-HRMS). In order to process large and complex three dimensional LC-HRMS datasets, the reported method uses a bucketing and presence-absence standardization strategy in addition to statistical analysis tools including principal component analysis (PCA) and cluster analysis. From a closely related group of Streptomyces isolated from geographically varied environments, we demonstrated that grouping bacteria according to the chemical diversity of produced metabolites is reproducible and provides greatly improved resolution for the discrimination of microbial strains compared to current molecular dereplication techniques. Importantly, this method provides the ability to identify putative novel chemical entities as natural product discovery leads.

  17. Mass Casualties and Health Care Following the Release of Toxic Chemicals or Radioactive Material—Contribution of Modern Biotechnology

    PubMed Central

    Göransson Nyberg, Ann; Stricklin, Daniela; Sellström, Åke

    2011-01-01

    Catastrophic chemical or radiological events can cause thousands of casualties. Such disasters require triage procedures to identify the development of health consequences requiring medical intervention. Our objective is to analyze recent advancements in biotechnology for triage in mass emergency situations. In addition to identifying persons “at risk” of developing health problems, these technologies can aid in securing the unaffected or “worried well”. We also highlight the need for public/private partnerships to engage in some of the underpinning sciences, such as patho-physiological mechanisms of chemical and radiological hazards, and for the necessary investment in the development of rapid assessment tools through identification of biochemical, molecular, and genetic biomarkers to predict health effects. For chemical agents, biomarkers of neurotoxicity, lung damage, and clinical and epidemiological databases are needed to assess acute and chronic effects of exposures. For radiological exposures, development of rapid, sensitive biomarkers using advanced biotechnologies are needed to sort exposed persons at risk of life-threatening effects from persons with long-term risk or no risk. The final implementation of rapid and portable diagnostics tools suitable for emergency care providers to guide triage and medical countermeasures use will need public support, since commercial incentives are lacking. PMID:22408587

  18. Excimer laser ablation mass spectrometry of inorganic solids: Chemical, matrix, and sampling effects on polyatomic ion yields

    SciTech Connect

    Gibson, J.K.

    1995-07-01

    Positive ions formed directly by excimer laser ablation in vacuum of several lanthanide (Ln) and transition metal solid materials---including Ln{sub 2}O{sub 3}, Ln{sub 2}S{sub 3}, LnF{sub 3}, Ta{sub 2}O{sub 5}, ZrO{sub 2}, TiO, and TiO{sub 2}---were identified by time-of-flight mass spectrometry. Variations in ion yields were investigated as a function of the composition of the precursor material, laser irradiance, and ion sampling delay after ablation. The compositions of the observed polyatomic ions reflected the distinctive chemistries of the metal constituents, but the ion yield distributions were not generally indicative of the particular chemical/valence constitution of the target material. For example, the yield of CeO{sup +} relative to Ce{sup +} was substantially greater from the trivalent cerium oxide, Ce{sub 2}(WO{sub 4}){sub 3}(s), than from tetravalent CeO{sub 2}(s). Observed ion distributions apparently reflected the chemical composition of the ablation plume and the degree of gas-phase recombination therein. The observed abundances of polyatomic ions were found to correlate well with their estimated bond strengths. Further obscuring the chemical composition of the progenitor, minor changes in ablation, and sampling parameters---especially irradiance and sampling delay---were often manifested as significant variations in relative ion intensities. {copyright} {ital 1995} {ital American} {ital Vacuum} {ital Society}

  19. Models of low-mass helium white dwarfs including gravitational settling, thermal and chemical diffusion, and rotational mixing

    NASA Astrophysics Data System (ADS)

    Istrate, A. G.; Marchant, P.; Tauris, T. M.; Langer, N.; Stancliffe, R. J.; Grassitelli, L.

    2016-10-01

    A large number of extremely low-mass helium white dwarfs (ELM WDs) have been discovered in recent years. The majority of them are found in close binary systems suggesting they are formed either through a common-envelope phase or via stable mass transfer in a low-mass X-ray binary (LMXB) or a cataclysmic variable (CV) system. Here, we investigate the formation of these objects through the LMXB channel with emphasis on the proto-WD evolution in environments with different metallicities. We study for the first time the combined effects of rotational mixing and element diffusion (e.g. gravitational settling, thermal and chemical diffusion) on the evolution of proto-WDs and on the cooling properties of the resulting WDs. We present state-of-the-art binary stellar evolution models computed with MESA for metallicities of Z = 0.02, 0.01, 0.001 and 0.0002, producing WDs with masses between 0.16-0.45 M⊙. Our results confirm that element diffusion plays a significant role in the evolution of proto-WDs that experience hydrogen shell flashes. The occurrence of these flashes produces a clear dichotomy in the cooling timescales of ELM WDs, which has important consequences e.g. for the age determination of binary millisecond pulsars. In addition, we confirm that the threshold mass at which this dichotomy occurs depends on metallicity. Rotational mixing is found to counteract the effect of gravitational settling in the surface layers of young, bloated ELM proto-WDs and therefore plays a key role in determining their surface chemical abundances, i.e. the observed presence of metals in their atmospheres. We predict that these proto-WDs have helium-rich envelopes through a significant part of their lifetime. This is of great importance as helium is a crucial ingredient in the driving of the κ-mechanism suggested for the newly observed ELM proto-WD pulsators. However, we find that the number of hydrogen shell flashes and, as a result, the hydrogen envelope mass at the beginning of

  20. Atmospheric pressure mass spectrometry: a new analytical chemical characterization method for dissolved organic matter in rainwater.

    PubMed

    Seitzinger, Sybil P; Styles, Renée M; Lauck, Ron; Mazurek, Monica A

    2003-01-01

    The complex mixture of organic compounds in the atmosphere influences climate, air quality, and ecosystem processes. Atmospheric pressure electrospray ionization mass spectrometry (APESI-MS) was evaluated as a potential tool for direct measurement of the total suite of individual dissolved organic matter (DOM) compounds in rainwater. The APESI-MS response was linear to all DOM compounds of atmospheric significance examined as standard solutions. Urban precipitation samples from New Brunswick, NJ (USA) were analyzed by APESI-MS over the mass-to-charge (m/z) range 50-3,000. Over 95% of the m/z ions detected were in the low m/z range (50-500). Over 300 unique m/z ions were detected across the 11 rainwater samples indicating the complexity of the mixture of DOM in rainwater. Forty percent of the organic bases (positive mode detection) and 22% of the organic acids (negative mode) occurred in at least 6 of the 11 rainwater samples. Ions corresponding to the m/z of carboxylic acids standards (nonanedioic acid; 1,4-butanedicarboxylic acid; pentanedioic acid; hydroxybutanedioic acid; and butanedioic acid) and to reduced N standards (allylurea; caffeine; imidazole; and N-2-propenylurea) occurred in at least one of the 11 rainwater samples. Total dissolved organic carbon (DOC) estimated from the APESI-MS analysis and measured by standard DOC methods were not statistically different.

  1. Calculation of eddy viscosity in a compressible turbulent boundary layer with mass injection and chemical reaction

    NASA Technical Reports Server (NTRS)

    Omori, S.; Gross, K. W.

    1973-01-01

    The turbulent kinetic energy equation is coupled with boundary layer equations to solve the characteristics of compressible turbulent boundary layers with mass injection and combustion. The Reynolds stress is related to the turbulent kinetic energy using the Prandtl-Wieghardt formulation. When a lean mixture of hydrogen and nitrogen is injected through a porous plate into the subsonic turbulent boundary layer of air flow and ignited by external means, the turbulent kinetic energy increases twice as much as that of noncombusting flow with the same mass injection rate of nitrogen. The magnitudes of eddy viscosity between combusting and noncombusting flows with injection, however, are almost the same due to temperature effects, while the distributions are different. The velocity profiles are significantly affected by combustion. If pure hydrogen as a transpiration coolant is injected into a rocket nozzle boundary layer flow of combustion products, the temperature drops significantly across the boundary layer due to the high heat capacity of hydrogen. At a certain distance from the wall hydrogen reacts with the combustion products, liberating an extensive amount of heat.

  2. A Diamond Anniversary Perspective on "The Effects of Assimilation": Energy, Mass and Chemical Constraints on Open-System Magmatic Processes

    NASA Astrophysics Data System (ADS)

    Bohrson, W. A.; Spera, F. J.

    2002-12-01

    In "The Evolution of Igneous Rocks," (1928) Norman Bowen described the ongoing debate regarding the role that "foreign material" plays in generating compositional diversity in terrestrial magmas. A critical aspect of Bowen"s discussion of "The Effects of Assimilation" (Ch. 10) centered on the availability of enough energy to generate assimilant melt, and the effects that assimilation has on magma composition. Seventy-five years later, this debate is just as lively and reflects fundamental questions in igneous petrology/geochemistry: What are the energy, mass and chemical consequences of open-system magmatic processes, and how do these processes complicate our ability to characterize the mantle? Energy-Constrained Recharge, Assimilation, Fractional Crystallization (EC-RAFC) is a tool that tracks the thermochemical evolution of a magma body (melt+solids) undergoing recharge, assimilation, and fractional crystallization. The EC-RAFC algorithm is based on solution of a system of coupled non-linear differential equations that express conservation of energy (enthalpy), mass and species (trace elements, isotope ratios). The constraint of energy conservation provides information about the efficacy of assimilation in a range of thermal environments. For example, EC-RAFC results suggest that mafic magma intruded into mafic lower crust can assimilate up to 40% of the original mass of the magma body, yielding ratios of mass of material assimilated/mass of material crystallized of up to 0.8. For typical lower crustal Sr concentrations ([Sr]) and isotope values (230 ppm, 0.7100), the Sr isotope signature of a mafic magma (400 ppm, 0.7035) can increase by up to 1500 ppm. Production of mafic magmas with more radiogenic Sr isotope values and relatively enriched [Sr] is favored by lower crust that has a lower liquidus temperature and/or is thermally mature. The ability to track the mass and chemical consequences of wallrock partial melting further illustrates the importance of the

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

    PubMed

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

    2015-02-01

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

  4. The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

    SciTech Connect

    Martin, Audrey Noreen

    2006-01-01

    Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle (~1 pg) without the need for consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA simulants using one set of operational conditions is established.

  5. Microfluidic Device for the Selective Chemical Stimulation of Neurons and Characterization of Peptide Release with Mass Spectrometry

    PubMed Central

    2012-01-01

    Neuropeptides are synthesized in and released from neurons and are involved in a wide range of physiological processes, including temperature homeostasis, learning, memory, and disease. When working with sparse neuronal networks, the ability to collect and characterize small sample volumes is important as neurons often release only a small proportion of their mass-limited content. Microfluidic systems are well suited for the study of neuropeptides. They offer the ability to control and manipulate the extracellular environment and small sample volumes, thereby reducing the dilution of peptides following release. We present an approach for the culture and stimulation of a neuronal network within a microfluidic device, subsequent collection of the released peptides, and their detection via mass spectrometry. The system employs microvalve-controlled stimulation channels to selectively stimulate a low-density neuronal culture, allowing us to determine the temporal onset of peptide release. Released peptides from the well-characterized, peptidergic bag cell neurons of Aplysia californica were collected and their temporal pattern of release was characterized with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. We show a robust difference in the timing of release for chemical solutions containing elevated K+ (7 ± 3 min), when compared to insulin (19 ± 7 min) (p < 0.000 01). PMID:23004687

  6. Chemical composition, sources, and processes of urban aerosols during summertime in Northwest China: insights from High Resolution Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Xu, J.; Zhang, Q.; Chen, M.; Ge, X.; Ren, J.; Qin, D.

    2014-06-01

    An aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed along with a Scanning Mobility Particle Sizer (SMPS) and a Multi Angle Absorption Photometers (MAAP) to measure the temporal variations of the mass loading, chemical composition, and size distribution of sub-micrometer particulate matter (PM1) in Lanzhou, northwest China, during 12 July-7 August 2012. The average PM1 mass concentration including non-refractory PM1 (NR-PM1) measured by HR-ToF-AMS and black carbon (BC) measured by MAAP during this study was 24.5 μg m-3 (ranging from 0.86 to 105μg m-3), with a mean composition consisting of 47% organics, 16% sulfate, 12% BC, 11% ammonium, 10% nitrate, and 4% chloride. The organics was consisted of 70% carbon, 21% oxygen, 8% hydrogen, and 1% nitrogen, with the average oxygen-to-carbon ratio (O / C) of 0.33 and organic mass-to-carbon ratio (OM / OC) of 1.58. Positive matrix factorization (PMF) of the high-resolution mass spectra of organic aerosols (OA) identified four distinct factors which represent, respectively, two primary OA (POA) emission sources (traffic and food cooking) and two secondary OA (SOA) types - a fresher, semi-volatile oxygenated OA (SV-OOA) and a more aged, low-volatility oxygenated OA (LV-OOA). Traffic-related hydrocarbon-like OA (HOA) and BC displayed distinct diurnal patterns both with peak at ~07:00-11:00 (BJT: UTC +8) corresponding to the morning rush hours, while cooking OA (COA) peaked during three meal periods. The diurnal profiles of sulfate and LV-OOA displayed a broad peak between ∼07:00-15:00, while those of nitrate, ammonium, and SV-OOA showed a narrower peak at ~08:00-13:00. The later morning and early afternoon peak in the diurnal profiles of secondary aerosol species was likely caused by mixing down of pollutants aloft, which were likely produced in the residual layer decoupled from the boundary layer during night time. The mass spectrum of SV-OOA also showed similarity with that of

  7. Neurosciences and research on chemical weapons of mass destruction in Nazi Germany.

    PubMed

    Schmaltz, Florian

    2006-09-01

    As a side-product of industrial research, new chemical nerve agents (Tabun, Sarin, Soman) superior to those available to the Allied Forces were discovered in Nazi Germany. These agents were never used by Germany, even though they were produced at a large scale. This article explores the toxicological and physiological research into the mechanisms of action of these novel nerve agents, and the emergence of military research objectives in neurophysiological and neurotoxicological research. Recently declassified Allied military intelligence files document secret nerve agent research, leading to intensified research on anticholinesterase agents in the peripheral and the central nervous system. The article discusses the involvement of IG Farben scientists, educational, medical and military institutions, and of Nobel Prize laureate Richard Kuhn, director of the Kaiser Wilhelm Institute for Medical Research.

  8. Chemical Effects in the Separation Process of a Differential Mobility / Mass Spectrometer System

    PubMed Central

    Schneider, Bradley B.; Covey, Thomas R.; Coy, Stephen L.; Krylov, Evgeny V.; Nazarov, Erkinjon G.

    2013-01-01

    In differential mobility spectrometry (DMS, also referred to as high field asymmetric waveform ion mobility spectrometry, FAIMS), ions are separated on the basis of the difference in their mobility under high and low electric fields. The addition of polar modifiers to the gas transporting the ions through a DMS enhances the formation of clusters in a field-dependent way and thus amplifies the high and low field mobility difference resulting in increased peak capacity and separation power. Observations of the increase in mobility field dependence are consistent with a cluster formation model, also referred to as the dynamic cluster-decluster model. The uniqueness of chemical interactions that occur between an ion and cluster-forming neutrals increases the selectivity of the separation and the depression of low-field mobility relative to high-field mobility increases the compensation voltage and peak capacity. The effect of polar modifiers on the peak capacity across a broad range of chemicals has been investigated. We discuss the theoretical underpinnings which explain the observed effects. In contrast to the result from polar modifiers, we find that using mixtures of inert gases as the transport gas improve resolution by reducing peak width but has very little effect on peak capacity or selectivity. Inert gases do not cluster and thus do not reduce low field mobility relative to high-field mobility. The observed changes in the differential mobility α parameter exhibited by different classes of compounds when the transport gas contains polar modifiers or has a significant fraction of inert gas can be explained on the basis of the physical mechanisms involved in the separation processes. PMID:20121077

  9. A chemical precursor to optical damage. Studies by laser ionization mass spectrometry

    SciTech Connect

    Nogar, N.S.; Estler, R.C.

    1987-01-01

    Mass spectrometry has been used in conjunction with Nomarski microscopy to characterize the initiation of optical damage in selected commercial optics. For a sample with an Al/sub 2/O/sub 3//SiO/sub 2/ multilayer coating (351 nm) on a Si substrate, our results suggest layer by layer removal of the coating material with low-fluence irradiation at 1.06 mu. In addition, carbon impurities were observed in the low-damage threshold sample. For the Sc/sub 2/O/sub 3//SiO/sub 2/ multilayer coated (351 nm) 7940 substrates, transient iron signals were observed at each increasing fluence level, with concomitant appearance of small circular (10 mu) pits in the surface. These pits were also associated with macroscopic damage features due to threshold testing.

  10. PM2.5 mass, chemical composition, and light extinction before and during the 2008 Beijing Olympics

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; He, Kebin; Li, Chengcai; Yang, Fumo; Zhao, Qing; Ma, Yongliang; Cheng, Yuan; Ouyang, Wenjuan; Chen, Gangcai

    2013-11-01

    contrast of air quality and visibility before and during the 2008 Beijing Olympic Games provides a rare opportunity to investigate the links between PM2.5 mass, chemical composition, and light extinction in this megacity. Twenty-four hour integrated PM2.5 samples were collected, and light scattering coefficients and the concentrations of black carbon were measured at urban Beijing for this purpose during a measurement campaign from 1 July to 20 September 2008, which was classed into four stages according to the levels of emission control measures. Daily PM2.5 concentrations ranged from 15.9 to 156.7 µg m-3 with an average of 66.0 ± 35.1 µg m-3. The average PM2.5 mass during the Olympics decreased by 49% from the second stage (20 July to 7 August), mainly due to the reduction of secondary inorganic aerosols (i.e., sulfate, nitrate, and ammonium (SNA)). The counterintuitive increase of PM2.5 mass (by 27% on average) during the second stage with two most serious haze episodes, although more rigorous emission control measures were in place, compared to the first stage (1-19 July), was mainly explained by the unfavorable meteorology and input of sulfate aerosols. A daily PM2.5 mass threshold of 50 µg m-3 was extracted for frequent haze occurrence. The extinction fractions of SNA and organic material were each approximately 30% during the 20% best visibility days but changed to 81.7% and 8.4%, respectively, during the 20% worst visibility days. The results indicated that the role of SNA was magnified in haze formation during the 2008 summer in Beijing.

  11. Sensitive monitoring of volatile chemical warfare agents in air by atmospheric pressure chemical ionization mass spectrometry with counter-flow introduction.

    PubMed

    Seto, Yasuo; Kanamori-Kataoka, Mieko; Tsuge, Koichiro; Ohsawa, Isaac; Iura, Kazumitsu; Itoi, Teruo; Sekiguchi, Hiroyuki;