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Sample records for chloromethane

  1. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane

    Directory of Open Access Journals (Sweden)

    Joshua Michener

    2016-07-01

    Full Text Available Chloromethane is an ozone-depleting gas, produced predominantly from natural sources, that provides an important carbon source for microbes capable of consuming it. Chloromethane catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for chloromethane catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new chloromethane-catabolizing strains in tractable hosts. We demonstrate that six putative accessory genes improve chloromethane catabolism, though heterologous expression of only one of the six is strictly necessary for growth on chloromethane. In contrast to growth of Methylobacterium strains with the closely-related compound dichloromethane, we find that chloride export does not limit growth on chloromethane and, in general, that the ability of a strain to grow on dichloromethane is uncorrelated with its ability to grow on chloromethane. This heterologous expression system allows us to investigate the components required for effective chloromethane catabolism and the factors that limit effective catabolism after horizontal transfer.

  2. Chloromethane and dichloromethane in the tropical Atlantic Ocean

    Science.gov (United States)

    Kolusu, Seshagiri Rao; Schlünzen, K. Heinke; Grawe, David; Seifert, Richard

    2017-02-01

    Chloromethane and dichloromethane were measured in the air of marine environment and in seawater during a cruise from the Port of Spain to Rio de Janeiro in the tropical Atlantic Ocean in April and May of 2009. Variation of chloromethane and dichloromethane concentrations was analysed as a function of latitude. There is no correlation observed between chloromethane and dichloromethane concentrations in the seawater suggest that they may not have a common oceanic source. In addition, a relation of concentrations, fluxes and sea surface temperature were studied to determine a dependency of concentrations and fluxes on sea surface temperature. Sea surface temperature does not show any significant effect on dichloromethane concentrations in surface seawater. Chloromethane and dichloromethane are supersaturated in the seawater during the cruise. This implies that the tropical Atlantic Ocean emits chloromethane and dichloromethane into the atmosphere. The tropical Atlantic Ocean mean fluxes of chloromethane and dichloromethane during the cruise were 150 nmol m-2 d-1 and 81 nmol m-2 d-1, respectively. The backward trajectory analysis revealed that the tropical Atlantic Ocean and African coast were primary and secondary source regions for chloromethane and dichloromethane respectively, during the Meteor cruise.

  3. IDENTIFICATION OF CHLOROMETHANE FORMATION PATHS DURING ELECTROCHEMICAL DECHLORINATION OF TCE USING GRAPHITE ELECTRODES

    Science.gov (United States)

    The purpose of this research is to investigate the formation of chloromethane during TCE dechlorination in a mixed electrochemical reactor using graphite electrodes. Chloromethane was the major chlorinated organic compound detected in previous dechlorination experiments. In order...

  4. Mechanistic aspects of the nucleophilic substitution of pectin. On the formation of chloromethane

    DEFF Research Database (Denmark)

    Sailaukhanuly, Yerbolat; Sárossy, Zsuzsa; Carlsen, Lars

    2014-01-01

    Chloromethane, accounting for approximately 16% of the tropospheric chlorine, is mainly coming from natural sources. However anthropogenic activities, such as combustion of biomass may contribute significantly as well. The present study focuses on the thermal solid state reaction between pectin, ...

  5. The 380 kb pCMU01 plasmid encodes chloromethane utilization genes and redundant genes for vitamin B12- and tetrahydrofolate-dependent chloromethane metabolism in Methylobacterium extorquens CM4: a proteomic and bioinformatics study.

    Directory of Open Access Journals (Sweden)

    Sandro Roselli

    Full Text Available Chloromethane (CH3Cl is the most abundant volatile halocarbon in the atmosphere and contributes to the destruction of stratospheric ozone. The only known pathway for bacterial chloromethane utilization (cmu was characterized in Methylobacterium extorquens CM4, a methylotrophic bacterium able to utilize compounds without carbon-carbon bonds such as methanol and chloromethane as the sole carbon source for growth. Previous work demonstrated that tetrahydrofolate and vitamin B12 are essential cofactors of cmuA- and cmuB-encoded methyltransferases of chloromethane dehalogenase, and that the pathway for chloromethane utilization is distinct from that for methanol. This work reports genomic and proteomic data demonstrating that cognate cmu genes are located on the 380 kb pCMU01 plasmid, which drives the previously defined pathway for tetrahydrofolate-mediated chloromethane dehalogenation. Comparison of complete genome sequences of strain CM4 and that of four other M. extorquens strains unable to grow with chloromethane showed that plasmid pCMU01 harbors unique genes without homologs in the compared genomes (bluB2, btuB, cobA, cbiD, as well as 13 duplicated genes with homologs of chromosome-borne genes involved in vitamin B12-associated biosynthesis and transport, or in tetrahydrofolate-dependent metabolism (folC2. In addition, the presence of both chromosomal and plasmid-borne genes for corrinoid salvaging pathways may ensure corrinoid coenzyme supply in challenging environments. Proteomes of M. extorquens CM4 grown with one-carbon substrates chloromethane and methanol were compared. Of the 49 proteins with differential abundance identified, only five (CmuA, CmuB, PurU, CobH2 and a PaaE-like uncharacterized putative oxidoreductase are encoded by the pCMU01 plasmid. The mainly chromosome-encoded response to chloromethane involves gene clusters associated with oxidative stress, production of reducing equivalents (PntAA, Nuo complex, conversion of

  6. Theoretical Chemistry Study of the Hydrogen-bonded Interaction between Acylamine and Chloromethane Compounds

    Institute of Scientific and Technical Information of China (English)

    GE Qing-Yu; WANG Hai-Jun; CHEN Jian-Hua

    2005-01-01

    The hydrogen-bonded interaction between acylamine and chloromethane was studied using theoretical calculation methods. Looking the interaction system as a hydrogen-bonded complex, the geometric optimization of the interaction system was performed with HF and B3LYP methods at 6-311++G** level. Stable structures of these complexes were obtained. Binding energies and some other physical chemistry parameters of them were computed and compared. According to the calculation results, it can be identified that DMA (DMF or DEF) can form stable complex with chloromethane by the hydrogen-bonded interaction between them. The stable orders of these hydrogen-bonded complexes were obtained and described as: DMF-CHCl3>DMF-CH2Cl2>DMF-CH3Cl, DEF-CHCl3>DEF-CH2Cl2>DEF-CH3Cl, DMA-CHCl3>DMA-CH2Cl2>DMA-CH3Cl, respectively.

  7. Probing the diversity of chloromethane-degrading bacteria by comparative genomics and isotopic fractionation.

    Science.gov (United States)

    Nadalig, Thierry; Greule, Markus; Bringel, Françoise; Keppler, Frank; Vuilleumier, Stéphane

    2014-01-01

    Chloromethane (CH3Cl) is produced on earth by a variety of abiotic and biological processes. It is the most important halogenated trace gas in the atmosphere, where it contributes to ozone destruction. Current estimates of the global CH3Cl budget are uncertain and suggest that microorganisms might play a more important role in degrading atmospheric CH3Cl than previously thought. Its degradation by bacteria has been demonstrated in marine, terrestrial, and phyllospheric environments. Improving our knowledge of these degradation processes and their magnitude is thus highly relevant for a better understanding of the global budget of CH3Cl. The cmu pathway, for chloromethane utilisation, is the only microbial pathway for CH3Cl degradation elucidated so far, and was characterized in detail in aerobic methylotrophic Alphaproteobacteria. Here, we reveal the potential of using a two-pronged approach involving a combination of comparative genomics and isotopic fractionation during CH3Cl degradation to newly address the question of the diversity of chloromethane-degrading bacteria in the environment. Analysis of available bacterial genome sequences reveals that several bacteria not yet known to degrade CH3Cl contain part or all of the complement of cmu genes required for CH3Cl degradation. These organisms, unlike bacteria shown to grow with CH3Cl using the cmu pathway, are obligate anaerobes. On the other hand, analysis of the complete genome of the chloromethane-degrading bacterium Leisingera methylohalidivorans MB2 showed that this bacterium does not contain cmu genes. Isotope fractionation experiments with L. methylohalidivorans MB2 suggest that the unknown pathway used by this bacterium for growth with CH3Cl can be differentiated from the cmu pathway. This result opens the prospect that contributions from bacteria with the cmu and Leisingera-type pathways to the atmospheric CH3Cl budget may be teased apart in the future.

  8. Probing the diversity of chloromethane-degrading bacteria by comparative genomics and isotopic fractionation

    Directory of Open Access Journals (Sweden)

    Thierry eNADALIG

    2014-10-01

    Full Text Available Chloromethane (CH3Cl is produced on earth by a variety of abiotic and biological processes. It is the most important halogenated trace gas in the atmosphere, where it contributes to ozone destruction. Current estimates of the global CH3Cl budget are uncertain and suggest that microorganisms might play a more important role in degrading atmospheric CH3Cl than previously thought. Its degradation by bacteria has been demonstrated in marine, terrestrial and phyllospheric environments. Improving our knowledge of these degradation processes and its magnitude is thus highly relevant for a better understanding of the global budget of CH3Cl.The cmu pathway, for chloromethane utilisation, is the only microbial pathway for CH3Cl degradation elucidated so far, and was characterised in detail in aerobic methylotrophic Alphaproteobacteria. Here, we reveal the potential of using a two-pronged approach involving a combination of comparative genomics and isotopic fractionation during CH3Cl degradation to newly address the question of the diversity of chloromethane-degrading bacteria in the environment.Analysis of available bacterial genome sequences reveals that several bacteria not yet known to degrade CH3Cl contain part or all of the complement of cmu genes required for CH3Cl degradation. These organisms, unlike bacteria shown to grow with CH3Cl using the cmu pathway, are obligate anaerobes. On the other hand, analysis of the complete genome of the chloromethane-degrading bacterium Leisingera methylohalidivorans showed that this bacterium does not contain cmu genes. Isotope fractionation experiments with L. methylohalidivorans suggest that the unknown pathway used by this bacterium for growth with CH3Cl can be differentiated from the cmu pathway. This result opens the prospect that contributions from bacteria with the cmu and Leisingera-type pathways to the atmospheric CH3Cl budget may be teased apart in the future.

  9. Chloromethane-Dependent Expression of the cmu Gene Cluster of Hyphomicrobium chloromethanicum

    OpenAIRE

    Borodina, Elena; McDonald, Ian R.; Murrell, J. Colin

    2004-01-01

    The methylotrophic bacterium Hyphomicrobium chloromethanicum CM2 can utilize chloromethane (CH3Cl) as the sole carbon and energy source. Previously genes cmuB, cmuC, cmuA, and folD were shown to be essential for the growth of Methylobacterium chloromethanicum on CH3Cl. These CH3Cl-specific genes were subsequently detected in H. chloromethanicum. Transposon and marker exchange mutagenesis studies were carried out to identify the genes essential for CH3Cl metabolism in H. chloromethanicum. New ...

  10. Low-energy elastic electron scattering from chloromethane, CH3Cl

    Science.gov (United States)

    Navarro, C.; Sakaamini, A.; Cross, J.; Hargreaves, L. R.; Khakoo, M. A.; Fedus, Kamil; Winstead, C.; McKoy, V.

    2015-10-01

    We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloromethane, CH3Cl, also known as methyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 0.5 to 100 eV and at scattering angles from {5}\\circ to {125}\\circ . We compare our data to earlier previous results for this molecule.

  11. Simultaneous coking and dealumination of zeolite H-ZSM-5 during the transformation of chloromethane into olefins

    NARCIS (Netherlands)

    Ibanez, M.; Gamero, M.; Ruiz-Martinez, J.; Weckhuysen, B. M.; Aguayo, A. T.; Bilbao, J.; Castano, P.

    2016-01-01

    The deactivation pathways of a zeolite H-ZSM-5 catalyst containing bentonite and alpha-Al2O3 as binder material have been studied during the transformation of chloromethane into light olefins, which is considered as a possible step to valorize methane from natural gas. The reactions have been carrie

  12. Chloromethane Utilization Gene Cluster from Hyphomicrobium chloromethanicum Strain CM2T and Development of Functional Gene Probes To Detect Halomethane-Degrading Bacteria

    OpenAIRE

    McAnulla, Craig; Woodall, Claire A.; McDonald, Ian R.; Studer, Alex; Vuilleumier, Stephane; Leisinger, Thomas; Murrell, J. Colin

    2001-01-01

    Hyphomicrobium chloromethanicum CM2T, an aerobic methylotrophic member of the α subclass of the class proteobacteria, can grow with chloromethane as the sole carbon and energy source. H. chloromethanicum possesses an inducible enzyme system for utilization of chloromethane, in which two polypeptides (67-kDa CmuA and 35-kDa CmuB) are expressed. Previously, four genes, cmuA, cmuB, cmuC, and purU, were shown to be essential for growth of Methylobacterium chloromethanicum on chloromethane. The cm...

  13. Crystal Structure of 1-(N-Dichlorophosphoryl-N- cyclohexyl)-amino-1-dichlorophosphinyl-chloromethane

    Institute of Scientific and Technical Information of China (English)

    吴明书; 陈茹玉; 黄有

    2004-01-01

    The crystal and molecular structures of 1-(N-dichlorophosphoryl-N-cyclohexyl) amino-1-dichlorophosphinyl-chloromethane have been determined by X-ray diffraction. The crystal (C7H12Cl5NO2P2) is of orthorhombic, space group Pbca with a = 11.104(7), b = 11.290(6), c = 24.403(14) A, V = 3059(3) A3, Mr = 381.37, Z = 8, Dc = 1.656 g/cm3, μ = 1.146 mm-1, F(000) = 1536, the final R = 0.0391 and Rw = 0.0778 for 2657 observed reflections with I > 2σ(I). The crystallographic results of the title compound show that the N atom is not a conventionally sp3 hybridized tetrahedron but an sp2 hybridized triangular planar nitrogen.

  14. Catalytic conversion of chloromethane to methanol and dimethyl ether over two catalytic beds: a study of acid strength

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, D.R.; Leite, T.C.M.; Mota, C.J.A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica], e-mail: cmota@iq.ufrj.br

    2010-07-15

    The catalytic hydrolysis of chloromethane to methanol and dimethyl ether (DME) was studied over metal-exchanged Beta and Mordenite zeolites, acidic MCM-22 and SAPO-5. The use of a second catalytic bed with HZSM-5 zeolite increased the selectivity to DME, due to methanol dehydration on the acid sites. The effect was more significant on catalysts presenting medium and weak acid site distribution, showing that dehydration of methanol to DME is accomplished over sites of higher acid strength. (author)

  15. Chloromethane release from carbonaceous meteorite affords new insight into Mars lander findings.

    Science.gov (United States)

    Keppler, Frank; Harper, David B; Greule, Markus; Ott, Ulrich; Sattler, Tobias; Schöler, Heinz F; Hamilton, John T G

    2014-11-13

    Controversy continues as to whether chloromethane (CH3Cl) detected during pyrolysis of Martian soils by the Viking and Curiosity Mars landers is indicative of organic matter indigenous to Mars. Here we demonstrate CH3Cl release (up to 8 μg/g) during low temperature (150-400°C) pyrolysis of the carbonaceous chondrite Murchison with chloride or perchlorate as chlorine source and confirm unequivocally by stable isotope analysis the extraterrestrial origin of the methyl group (δ(2)H +800 to +1100‰, δ(13)C -19.2 to +10‰,). In the terrestrial environment CH3Cl released during pyrolysis of organic matter derives from the methoxyl pool. The methoxyl pool in Murchison is consistent both in magnitude (0.044%) and isotope signature (δ(2)H +1054 ± 626‰, δ(13)C +43.2 ± 38.8‰,) with that of the CH3Cl released on pyrolysis. Thus CH3Cl emissions recorded by Mars lander experiments may be attributed to methoxyl groups in undegraded organic matter in meteoritic debris reaching the Martian surface being converted to CH3Cl with perchlorate or chloride in Martian soil. However we cannot discount emissions arising additionally from organic matter of indigenous origin. The stable isotope signatures of CH3Cl detected on Mars could potentially be utilized to determine its origin by distinguishing between terrestrial contamination, meteoritic infall and indigenous Martian sources.

  16. Synthesis and characterization of bifunctional transition-metal/silica-alumina catalysts for the chloromethane conversion to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, J.F. [Universidade Federal de Rio de Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Engenharia Quimica; Rojas, L.O.A.; Nascimento, J.C. [Universidade Federal de Rio de Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Engenharia Quimica; Centro de Tecnologias do Gas (CTGAS), Natal, RN (Brazil)], E-mail: leopoldo@ctgas.com.br; Ruiz, J.A.C. [Centro de Tecnologias do Gas (CTGAS), Natal, RN (Brazil); Benachour, M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Programa de Pos-Graduacao em Engenharia Quimica

    2008-10-15

    In this work bifunctional (metal-acid) catalysts of Fe, Ni, Fe{sub 2}O{sub 3} and NiO over amorphous silica alumina support were characterized (acidity) and evaluated for the conversion of chloromethane in a fixed bed reactor. Temperature program tests TPD (Temperature Programmed Desorption) and TPR (Temperature Programmed Reduction) were performed to characterize the chemisorption sites for the impregnated and unimpregnated support. New adsorption sites were created on the metal supported catalysts. The conversion yield of chloromethane was evaluated for the five materials. The highest conversion conversion (85%) was observed for the unmodified support (SiAl) after 6 of reaction at 860 K and a WHSV (Weight Hourly Space Velocity) of 4,5 h{sup -1}. The best selectivity toward desirable hydrocarbons (C{sup 3}, C{sup 4}) was found for the Fe-SiAl catalyst. C{sup 3} was also found in the products stream when Ni/SiAl and NiO/SiAl catalysts were tested. Ni catalysts were the most favorable to methane production. The catalytic tests showed coke formation in all materials. For the SiAl support the desorption energy of chloromethane, determined by TPD runs, was 101,9 KJ/mol. The metals presented lower desorption energies (75,2 KJ/mol for Ni and 133,4 KJ/mol for Fe) than the oxides (190,1 KJ/mol for Fe{sub 2}O{sub 3} and 322,4 KJ/mol for NiO). (author)

  17. Chloromethane-dependent expression of the cmu gene cluster of Hyphomicrobium chloromethanicum.

    Science.gov (United States)

    Borodina, Elena; McDonald, Ian R; Murrell, J Colin

    2004-07-01

    The methylotrophic bacterium Hyphomicrobium chloromethanicum CM2 can utilize chloromethane (CH(3)Cl) as the sole carbon and energy source. Previously genes cmuB, cmuC, cmuA, and folD were shown to be essential for the growth of Methylobacterium chloromethanicum on CH(3)Cl. These CH(3)Cl-specific genes were subsequently detected in H. chloromethanicum. Transposon and marker exchange mutagenesis studies were carried out to identify the genes essential for CH(3)Cl metabolism in H. chloromethanicum. New developments in genetic manipulation of Hyphomicrobium are presented in this study. An electroporation protocol has been optimized and successfully applied for transformation of mutagenesis plasmids into H. chloromethanicum to generate stable CH(3)Cl-negative mutants. Both transposon and marker exchange mutageneses were highly applicable for genetic analysis of Hyphomicrobium. A reliable and reproducible selection procedure for screening of CH(3)Cl utilization-negative mutants has also been developed. Mutational inactivation of cmuB, cmuC, or hutI resulted in strains that were unable to utilize CH(3)Cl or to express the CH(3)Cl-dependent polypeptide CmuA. Reverse transcription-PCR analysis indicated that cmuB, cmuC, cmuA, fmdB, paaE, hutI, and metF formed a single cmuBCA-metF operon and were coregulated and coexpressed in H. chloromethanicum. This finding led to the conclusion that, in cmuB and cmuC mutants, impaired expression of cmuA was likely to be due to a polar effect of the defective gene (cmuB or cmuC) located upstream (5') of cmuA. The detrimental effect of mutation in hutI on the upstream (5')-located cmuA is not clear but indicated that all the genes located within the cmuBCA-metF operon are coordinately expressed. Expression of the cmuBCA-metF transcript was also shown to be strictly CH(3)Cl inducible and was not repressed by the alternative C(1) substrate methanol. Sequence analysis of a transposon mutant (D20) led to the discovery of the previously

  18. An Effective Hamiltonian Molecular Orbital-Valence Bond (MOVB) Approach for Chemical Reactions Applied to the Nucleophilic Substitution Reaction of Hydrosulfide Ion and Chloromethane.

    Science.gov (United States)

    Song, Lingchun; Mo, Yirong; Gao, Jiali

    2009-01-01

    An effective Hamiltonian mixed molecular orbital and valence bond (EH-MOVB) method is described to obtain an accurate potential energy surface for chemical reactions. Building upon previous results on the construction of diabatic and adiabatic potential surfaces using ab initio MOVB theory, we introduce a diabatic-coupling scaling factor to uniformly scale the ab initio off-diagonal matrix element H(12) such that the computed energy of reaction from the EH-MOVB method is in agreement with the target value. The scaling factor is very close to unity, resulting in minimal alteration of the potential energy surface of the original MOVB model. Furthermore, the relative energy between the reactant and product diabatic states in the EH-MOVB method can be improved to match the experimental energy of reaction. A key ingredient in the EH-MOVB theory is that the off-diagonal matrix elements are functions of all degrees of freedom of the system and the overlap matrix is explicitly evaluated. The EH-MOVB method has been applied to the nucleophilic substitution reaction between hydrosulfide and chloromethane to illustrate the methodology and the results were matched to reproduce the results from ab initio valence bond self-consistent valence bond (VBSCF) calculations. The diabatic coupling (the off-diagonal matrix element in the generalized secular equation) has small variations along the minimum energy reaction path in the EH-MOVB model, whereas it shows a maximum value at the transition state and has nearly zero values in the regions of the ion-dipole complexes from VBSCF calculations. The difference in the diabatic coupling stabilization is attributed to the large overlap integral in the computationally efficient MOVB method.

  19. Halogen-abstraction reactions from chloromethane and bromomethane molecules by alkaline-earth monocations.

    Science.gov (United States)

    Redondo, Pilar; Largo, Antonio; Rayón, Víctor Manuel; Molpeceres, Germán; Sordo, José Ángel; Barrientos, Carmen

    2014-08-14

    The reactions, in the gas phase, between alkali-earth monocations (Mg(+), Ca(+), Sr(+), Ba(+)) and CH3X (X = Cl, Br) have been theoretically studied. The stationary points on the potential energy surfaces were characterized at the Density Functional Theory level on the framework of the mPW1K functional with the QZVPP Ahlrichs's basis sets. A complementary kinetics study has also been performed using conventional/variational microcanonical transition state theory. In the reactions of Mg(+) with either chloro- or bromomethane the transition structure lies in energy clearly above the reactants rendering thermal activation of CH3Cl or CH3Br extremely improbable. The remaining reactions are exothermic and barrierless processes; thus carbon-halogen bonds in chloro- or bromomethane can be activated by calcium, strontium or barium monocations to obtain the metal halogen cation and the methyl radical. The Mulliken population analysis for the stationary points of the potential energy surfaces supports a "harpoon"-like mechanism for the halogen-atom abstraction processes. An analysis of the bonding situation for the stationary points on the potential energy surface has also been performed in the framework of the quantum theory of atoms in molecules.

  20. RT3D Reaction Modules for Natural and Enhanced Attenuation of Chloroethanes, Chloroethenes, Chloromethanes, and Daughter Products

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Christian D.; Truex, Michael J.

    2006-07-25

    This document describes a suite of MNA/EA reaction modules that were developed for addressing complex chlorinated solvent reactions using RT3D. As an introduction, an overview of these MNA/EA reaction modules is presented, including discussions of similarities between reaction modules, the purpose of key reaction parameters, and important considerations for using the reaction modules. Subsequent sections provide the details of the reaction kinetics (conceptual model and equations), data input requirements, and example (batch reactor) results for each reaction module. This document does not discuss reaction module implementation or validation; such information will accompany the software in the form of release notes or a supplement to the RT3D manual.

  1. Selective esterification of non-conjugated carboxylic acids in the presence of conjugated or aromatic carboxylic acids over active carbon supported methanesulfonic acid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Non-conjugated carboxylic acids are selectively esterified in good yields in the presence of conjugated or aromatic carboxylic acids by stirring over active carbon supported methanesulfonic acid in di-chloromethane at room temperature.

  2. Method identification of capillary gas chromatography testing trichloromethane and tetra-chloromethane level in drinking water%毛细管气相色谱法测定生活饮用水中三氯甲烷和四氯化碳的方法确认

    Institute of Scientific and Technical Information of China (English)

    顾建华; 何鹏妍

    2008-01-01

    目的:确认调整后的测定生活饮用水中三氯甲烷和四氯化碳的方法能否符合国标检测要求.方法:采用顶空-毛细管气相色谱法测定,以方法的线性范围、线性关系、最低检出限、精密度等各方面的因素进行考察评定.结果:三氯甲烷和四氯化碳分别在0~200 mg/L和0~20.0 mg/L内线性关系良好,最低检出限分别为0.16 mg/L和0.0095 mg/L,RSD分别为4.1%和4.0%,回收率分别为100.3%~109.0%和89.8%-95.4%.结论:本方法的精密度和回收率与国标方法相当,线性范围优于国标法,满足实际检测需要.

  3. Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents

    Science.gov (United States)

    2004-08-01

    Tetrachloromethane/ Carbon Tetrachloride (CT) CCl4 153.8 (1) 1.58 (1) 0.0232 (4) 786 (4) 90 (3) 2.73 (4) 2.62 (4) Trichloromethane / Chloroform (CF) CHCl3... Trichloromethane / Chloroform (CF) CHCl3 119.38 Dichloromethane (DCM)/ Methylene Chloride (MC) CH2Cl2 84.93 Chloromethane CH3Cl1 50.49 Methane... Trichloromethane /Chloroform (CF) CHCl3 119.4 Dichloromethane (DCM)/ Methylene Chloride (MC) CH2Cl2 84.93 Chloromethane (CM) CH3Cl1 50.49 Methane

  4. SYNTHESIS OF MESOCYCLIC AND MACROCYCLIC THIACROWN ETHERS CONTAINING -SCH2SCH2S- UNITS USING THIO(BISCHLOROMETHANE)

    NARCIS (Netherlands)

    EDEMA, JJH; STOCK, HT; KELLOGG, RM

    1992-01-01

    Oxidative cleavage of 1,3,5-trithiane 1 by thionyl chloride is promoted by a catalytic quantity of a Lewis acid like zinc bromide or aluminum chloride and results in the formation of pure thiobis(chloromethane) (2). This reagent has been successfully employed in the straight-forward synthesis of a n

  5. Inferring marine sinks and sources of monohalomethanes from their carbon stable isotope composition

    Science.gov (United States)

    Bahlmann, Enno; Weinberg, Ingo; Eckhardt, Tim; Seifert, Richard; Michaelis, Walter

    2013-04-01

    Within the last years much progress in quantifying the global emissions of various halocarbons has been made. However, the current emission estimates are still assigned with large uncertainties due to the inevitably large spatial and temporal variability in observed halocarbon mixing ratios and fluxes. An improved understanding of the biogeochemical controls of the production - destruction equilibrium may substantially reduce these uncertainties and is of vital importance to address potential future changes. The δ13C values of monohalomethanes vary sensitively towards changes of both, sources and sinks making them a valuable tool to assess concurrent production and degradation processes. Here we report carbon isotope ratios for chloromethane (CH3Cl) and bromomethane (CH3Br) in background air and coastal and open ocean surface waters. The samples were taken during five sampling campaigns between September 2010 and July 2012 with the sample locations spanning from 10°N to 60°N Our results show an enrichment by about 4‰ for chloromethane in marine air masses (-36‰) as compared to continental air masses (-40‰) corroborating earlier findings. This enrichment is supported by the observation of even more enriched chloromethane in the ocean surface waters averaging -28‰ for the subtropical North East Atlantic. For bromomethane, our data show an even more pronounced enrichment by 16‰ from -44‰ in continental air masses to -28‰ in marine air masses. These isotopic differences can be attributed to the air sea exchange of these compounds in concert with the production - decomposition dynamics in surface oceans. Hydrolysis, assigned with an ɛ of 45‰, is regarded as the most important degradation process for chloromethane in surface oceans. Bromomethane from both, intrinsic sources and from the atmosphere, is known to be rapidly degraded in marine surface waters by biotic and abiotic processes. The abiotic degradation due to hydrolysis and transhalogenation

  6. Halite as a Methane Sequestration Host: A Possible Explanation for Periodic Methane Release on Mars, and a Surface-accessible Source of Ancient Martian Carbon

    Science.gov (United States)

    Fries, M. D.; Steele, Andrew; Hynek, B. M.

    2015-01-01

    We present the hypothesis that halite may play a role in methane sequestration on the martian surface. In terrestrial examples, halite deposits sequester large volumes of methane and chloromethane. Also, examples of chloromethane-bearing, approximately 4.5 Ga old halite from the Monahans meteorite show that this system is very stable unless the halite is damaged. On Mars, methane may be generated from carbonaceous material trapped in ancient halite deposits and sequestered. The methane may be released by damaging its halite host; either by aqueous alteration, aeolian abrasion, heating, or impact shock. Such a scenario may help to explain the appearance of short-lived releases of methane on the martian surface. The methane may be of either biogenic or abiogenic origin. If this scenario plays a significant role on Mars, then martian halite deposits may contain samples of organic compounds dating to the ancient desiccation of the planet, accessible at the surface for future sample return missions.

  7. Optimization of dynamic headspace extraction system for measurement of halogenated volatile organic compounds in liquid or viscous samples

    Science.gov (United States)

    Taniai, G.; Oda, H.; Kurihara, M.; Hashimoto, S.

    2010-12-01

    Halogenated volatile organic compounds (HVOCs) produced in the marine environment are thought to play a key role in atmospheric reactions, particularly those involved in the global radiation budget and the depression of tropospheric and stratospheric ozone. To evaluate HVOCs concentrations in the various natural samples, we developed an automated dynamic headspace extraction method for the determination of 15 HVOCs, such as chloromethane, bromomethane, bromoethane, iodomethane, iodoethane, bromochloromethane, 1-iodopropane, 2-iodopropane, dibromomethane, bromodichloromethane, chloroiodomethane, chlorodibromomethane, bromoiodomethane, tribromomethane, and diiodomethane. Dynamic headspace system (GERSTEL DHS) was used to purge the gas phase above samples and to trap HVOCs on the adsorbent column from the purge gas. We measured the HVOCs concentrations in the adsorbent column with gas chromatograph (Agilent 6890N)- mass spectrometer (Agilent 5975C). In dynamic headspace system, an glass tube containing Tenax TA or Tenax GR was used as adsorbent column for the collection of 15 HVOCs. The parameters for purge and trap extraction, such as purge flow rate (ml/min), purge volume (ml), incubation time (min), and agitator speed (rpm), were optimized. The detection limits of HVOCs in water samples were 1270 pM (chloromethane), 103 pM (bromomethane), 42.1 pM (iodomethane), and 1.4 to 10.2 pM (other HVOCs). The repeatability (relative standard deviation) for 15 HVOCs were < 9 % except chloromethane (16.2 %) and bromomethane (11.0 %). On the basis of the measurements for various samples, we concluded that this analytical method is useful for the determination of wide range of HVOCs with boiling points between - 24°C (chloromethane) and 181°C (diiodomethane) for the liquid or viscous samples.

  8. Reactive hydro- end chlorocarbons in the troposphere and lower stratosphere : sources, distributions, and chemical impact

    OpenAIRE

    H. A. Scheeren

    2003-01-01

    The work presented in this thesis focuses on measurements of chemical reactive C2 C7 non-methane hydrocarbons (NMHC) and C1 C2 chlorocarbons with atmospheric lifetimes of a few hours up to about a year. The group of reactive chlorocarbons includes the most abundant atmospheric species with large natural sources, which are chloromethane (CH3Cl), dichloromethane (CH2Cl2), and trichloromethane (CHCl3), and tetrachloroethylene (C2Cl4) with mainly anthropogenic sources. The NMHC and chlorocarbons ...

  9. Organic Molecules in the Sheepbed Mudstone, Gale Crater, Mars

    Science.gov (United States)

    Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Miller, K. E.; Eigenbrode, J. L.; Summons, R. E.; Brunner, A. E.; Buch, A.; Szopa, C.; Archer, P. D.; Franz, H. B.; Steele, A.

    2014-01-01

    The Sample Analysis at Mars (SAM) instrument on the Curiosity rover is designed to determine the inventory of organic and inorganic volatiles thermally released from solid samples using a combination of evolved gas analysis (EGA), gas chromatography mass spectrometry (GCMS), and tunable laser spectroscopy. Here we report on various chlorinated hydrocarbons (chloromethanes, chlorobenzene and dichloroalkanes) detected at elevated levels above instrument background at the Cumberland (CB) drill site, and discuss their possible sources.

  10. Evidence for Perchlorates and the Origin of Chlorinated Hydrocarbons Detected by SAM at the Rocknest Aeolian Deposit in Gale Crater

    Science.gov (United States)

    Glavin, Daniel P.; Freissinet, Caroline; Miller, Kristen E.; Eigenbrode, Jennifer L.; Brunner, Anna E.; Buch, Arnaud; Sutter, Brad; Archer, P. Douglas, Jr.; Atreya, Sushil K.; Brinckerhoff, William B.; Cabane, Michel; Coll, Patrice; Conrad, Pamela G.; Coscia, David; Dworkin, Jason P.; Franz, Heather B.; Grotzinger, John P.; Leshin, Laurie A.; Martin, Mildred G.; McKay, Christopher; Ming, Douglas W.; Navarro-Gonzalez, Rafael; Pavlov, Alexander; Steele, Andrew; Summons, Roger E.; Szopa, Cyril; Teinturier, Samuel; Mahaffy, Paul R.

    2013-01-01

    A single scoop of the Rocknest aeolian deposit was sieved (less than 150 micrometers), and four separate sample portions, each with a mass of approximately 50 mg, were delivered to individual cups inside the Sample Analysis at Mars (SAM) instrument by the Mars Science Laboratory rover's sample acquisition system. The samples were analyzed separately by the SAM pyrolysis evolved gas and gas chromatograph mass spectrometer analysis modes. Several chlorinated hydrocarbons including chloromethane, dichloromethane, trichloromethane, a chloromethylpropene, and chlorobenzene were identified by SAM above background levels with abundances of approximately 0.01 to 2.3 nmol. The evolution of the chloromethanes observed during pyrolysis is coincident with the increase in O2 released from the Rocknest sample and the decomposition of a product of N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), a chemical whose vapors were released from a derivatization cup inside SAM. The best candidate for the oxychlorine compounds in Rocknest is a hydrated calcium perchlorate (Ca(ClO4)2·nH2O), based on the temperature release of O2 that correlates with the release of the chlorinated hydrocarbons measured by SAM, although other chlorine-bearing phases are being considered. Laboratory analog experiments suggest that the reaction of Martian chlorine from perchlorate decomposition with terrestrial organic carbon from MTBSTFA during pyrolysis can explain the presence of three chloromethanes and a chloromethylpropene detected by SAM. Chlorobenzene may be attributed to reactions of Martian chlorine released during pyrolysis with terrestrial benzene or toluene derived from 2,6-diphenylphenylene oxide (Tenax) on the SAM hydrocarbon trap. At this time we do not have definitive evidence to support a nonterrestrial carbon source for these chlorinated hydrocarbons, nor do we exclude the possibility that future SAM analyses will reveal the presence of organic compounds native to the

  11. Synthesis of Pyridyl Polyheterocyclic Oxime-ether Schiff Bases Containing s-Triazole and Oxadiazole Subunits

    Institute of Scientific and Technical Information of China (English)

    Guo Qiang HU; Sheng LI; Wen Long HUANG

    2006-01-01

    4-Amino-5-pyridin-4-yl-s-triazole-3-thiol (1) was sequentally reacted with 3-chloro-1-phenylpropan-1-one to afford 3-(4-amino-5-pyridin-4-yl-s-triazole-3-sulfanyl)-1-phenylpropan-1-one (2) followed by oximation with hydroxylamine hydrochloride and etherification with 5-aryl-[13,4]oxadiazole-2-chloromethanes to the corresponding oxime (3) and oxime-ethers (4a-e),respectively. The condensation of compounds 4 with salicylaldehyde gave the title compounds (5a-e). The antibacterial activity in vitro against Gram-postive (G+) and Gram negative (G-)bacteria was primarily evaluated.

  12. Variational Flooding Study of a SN2 Reaction.

    Science.gov (United States)

    Piccini, GiovanniMaria; McCarty, James J; Valsson, Omar; Parrinello, Michele

    2017-02-02

    We have studied the reaction dynamics of a prototypical organic reaction using a variationally optimized truncated bias to accelerate transitions between educt and product reactant states. The asymmetric SN2 nucleophilic substitution reaction of fluoromethane and chloromethane CH3F + Cl(-) ⇌ CH3Cl + F(-) is considered, and many independent biased molecular dynamics simulations have been performed at 600, 900, and 1200 K, collecting several hundred transitions at each temperature. The transition times and relative rate constants have been obtained for both reaction directions. The activation energies extracted from an Arrhenius plot compare well with standard static calculations.

  13. Low-energy elastic electron scattering form chloroethane, C2H5Cl

    Science.gov (United States)

    Sakaamini, A.; Navarro, C.; Cross, J.; Hargreaves, L. R.; Khakoo, M. A.; Fedus, Kamil; Winstead, C.; McKoy, V.

    2015-10-01

    We report theoretical as well as (normalized) experimental differential and integral cross sections for vibrationally elastic scattering of low-energy electrons from chloroethane, C2H5Cl, also known as ethyl chloride. The theoretical cross sections were computed using the Schwinger multichannel variational method in the single-channel approximation, with polarization effects included via virtual excitations. Cross section measurements were made at incident energies ranging from 1 to 30 eV and at scattering angles from {10}\\circ to {125}\\circ . We compare our data to previous results for C2H5Cl and for the related molecule chloromethane.

  14. Effect of chloralkanes on the phenyltrichlorosilane synthesis by gas phase condensation

    Institute of Scientific and Technical Information of China (English)

    Tong Liu; Yunlong Huang; Chao Wang; Qiang Tang; Jinfu Wang

    2015-01-01

    To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.

  15. Evidence for perchlorates and the origin of chlorinated hydrocarbons detected by SAM at the Rocknest aeolian deposit in Gale Crater

    Science.gov (United States)

    Glavin, Daniel P.; Freissinet, Caroline; Miller, Kristen E.; Eigenbrode, Jennifer L.; Brunner, Anna E.; Buch, Arnaud; Sutter, Brad; Archer, P. Douglas; Atreya, Sushil K.; Brinckerhoff, William B.; Cabane, Michel; Coll, Patrice; Conrad, Pamela G.; Coscia, David; Dworkin, Jason P.; Franz, Heather B.; Grotzinger, John P.; Leshin, Laurie A.; Martin, Mildred G.; McKay, Christopher; Ming, Douglas W.; Navarro-González, Rafael; Pavlov, Alexander; Steele, Andrew; Summons, Roger E.; Szopa, Cyril; Teinturier, Samuel; Mahaffy, Paul R.

    2013-10-01

    A single scoop of the Rocknest aeolian deposit was sieved (trichloromethane, a chloromethylpropene, and chlorobenzene were identified by SAM above background levels with abundances of ~0.01 to 2.3 nmol. The evolution of the chloromethanes observed during pyrolysis is coincident with the increase in O2 released from the Rocknest sample and the decomposition of a product of N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), a chemical whose vapors were released from a derivatization cup inside SAM. The best candidate for the oxychlorine compounds in Rocknest is a hydrated calcium perchlorate (Ca(ClO4)2·nH2O), based on the temperature release of O2 that correlates with the release of the chlorinated hydrocarbons measured by SAM, although other chlorine-bearing phases are being considered. Laboratory analog experiments suggest that the reaction of Martian chlorine from perchlorate decomposition with terrestrial organic carbon from MTBSTFA during pyrolysis can explain the presence of three chloromethanes and a chloromethylpropene detected by SAM. Chlorobenzene may be attributed to reactions of Martian chlorine released during pyrolysis with terrestrial benzene or toluene derived from 2,6-diphenylphenylene oxide (Tenax) on the SAM hydrocarbon trap. At this time we do not have definitive evidence to support a nonterrestrial carbon source for these chlorinated hydrocarbons, nor do we exclude the possibility that future SAM analyses will reveal the presence of organic compounds native to the Martian regolith.

  16. Hybrid Quantum Mechanical and Molecular Mechanics Study of the SN2 Reaction of CCl4 + OH- in Aqueous Solution: The Potential of Mean Force, Reaction Energetics, and Rate Constants

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ting; Yin, Hongyun; Wang, Dunyou; Valiev, Marat

    2012-02-16

    The bimolecular nucleophilic substitution reaction of CCl{sub 4} and OH{sup -} in aqueous solution was investigated on the basis of a combined quantum mechanical and molecular mechanics method. A multilayered representation approach is employed to achieve high accuracy results at the CCSD(T) level of theory. The potential of mean force calculations at the DFT level and CCSD(T) level of theory yield reaction barrier heights of 22.7 and 27.9 kcal/mol, respectively. Both the solvation effects and the solvent-induced polarization effect have significant contributions to the reaction energetics, for example, the solvation effect raises the saddle point by 10.6 kcal/mol. The calculated rate constant coefficient is 8.6 x 10{sup -28} cm{sup 3} molecule{sup -1} s{sup -1} at the standard state condition, which is about 17 orders magnitude smaller than that in the gas phase. Among the four chloromethanes (CH{sub 3}Cl, CH{sub 2}Cl{sub 2}, CHCl{sub 3}, and CCl{sub 4}), CCl{sub 4} has the lowest free energy activation barrier for the reaction with OH{sup -1} in aqueous solution, confirming the trend that substitution of Cl by H in chloromethanes diminishes the reactivity.

  17. The Search for Organic Compounds of Martian Origin in Gale Crater by the Sample Analysis at Mars (SAM) Instrument on Curiosity

    Science.gov (United States)

    Glavin, Daniel; Freissinet, Caroline; Mahaffy, Paul; Miller, Kristen; Eigenbrode, Jennifer; Summons, Roger; Archer, Douglas, Jr.; Brunner, Anna; Martin, Mildred; Buch, Arrnaud; Cabane, Michel; Coll, Patrice; Conrad, Pamela; Dworkin, Jason; Grotzinger, John; Ming, Douglas; Navarro-Gonzales, Rafael; Steele, Andrew; Szopa, Cyril

    2014-01-01

    One of the key objectives of the Mars Science Laboratory rover and the Sample Analysis at Mars (SAM) instrument suite is to determine the inventory of organic and inorganic volatiles in the atmosphere and surface regolith and rocks to help assess the habitability potential of Gale Crater. The SAM instrument on the Curiosity rover can detect volatile organic compounds thermally evolved from solid samples using a combination of evolved gas analysis (EGA) and gas chromatography mass spectrometry (GCMS) (Mahaffy et al. 2012). The first solid samples analyzed by SAM, a scoop of windblown dust and sand at Rocknest, revealed several chloromethanes and a C4-chlorinated hydrocarbon derived primarily from reactions between a martian oxychlorine phase (e.g. perchlorate) and terrestrial carbon from N-methyl-N-(tertbutyldimethylsilyl)- trifluoroacetamide (MTBSTFA) vapor present in the SAM instrument background (Glavin et al. 2013). After the analyses at Rocknest, Curiosity traveled to Yellowknife Bay and drilled two separate holes in a fluvio-lacustrine sediment (the Sheepbed unit) designated John Klein and Cumberland. Analyses of the drilled materials by both SAM and the CheMin X-Ray Diffraction instrument revealed a mudstone consisting of 20 wt% smectite clays (Ming et al. 2013; Vaniman et al. 2013), which on Earth are known to aid the concentration and preservation of organic matter. Oxychlorine compounds were also detected in the Sheepbed mudstone during pyrolysis; however, in contrast to Rocknest, much higher levels of chloromethanes were released from the Sheepbed materials, suggesting an additional, possibly martian source of organic carbon (Ming et al. 2013). In addition, elevated abundances of chlorobenzene and a more diverse suite of chlorinated alkanes including dichloropropane and dichlorobutane detected in Cumberland compared to Rocknest suggest that martian or meteoritic organic carbon sources may be preserved in the mudstone (Freissinet et al. 2013

  18. Rotational Spectroscopy of ClZnCH3 (tilde{X}1A1): Characterization of a Monomeric Grignard-Type Reagent

    Science.gov (United States)

    Kilchenstein, K. M.; Min, Jie; Bucchino, Matthew; Ziurys, Lucy M.

    2016-06-01

    The pure rotational spectrum of the organozinc halide, ClZnCH3 (tilde{X}1A1), has been measured using Fourier-transform microwave (FTMW) and millimeter-wave direct-absorption methods in the frequency range 10-296 GHz. This work is the first study of ClZnCH3 by gas-phase spectroscopy. The molecule was created in a DC discharge from the reaction of zinc vapor, produced either by a Broida-type oven or by laser ablation, with chloromethane in what appears to be a metal insertion process. Rotational and chlorine quadrupole constants were determined for three zinc isotopologues. The Zn - Cl bond was found to be partly ionic and significantly shorter than in EtZnCl.

  19. Gaseous Products of Incense Coil Combustion Extracted by Passive Solid Phase Microextraction Samplers

    Directory of Open Access Journals (Sweden)

    Wen-Hsi Cheng

    2015-06-01

    Full Text Available Burning incense indoors is a common behavior in Southeast Asia. In this investigation, needle trap samplers (NTS, a novel, green analytical technology is used for sampling gaseous combustion by-products from sandalwood incense coils. To extract indoor volatile organic compounds (VOCs, two NTS are prepared, one using 60–80 mesh and the other using 100–120 mesh divinylbenzene (DVB particles packed in 22-gauge stainless steel needles. This work compares extraction efficiency of an NTS and that of a commercially available 100 μm polydimethylsiloxane solid phase microextration (PDMS-SPME fiber sampler. Experimental results indicated that the 100–120 mesh DVB-NTS performed best among all samplers during a 1 h sampling period. The main extracted compounds were toluene, ethylbenzene, propane, chloromethane, 1,3-butadiene, methanol and dichloromethane. The potential use of small badge-sized or pen-sized NTS for the indoor atmosphere and occupational hygiene applications is addressed.

  20. Gas phase ion-molecule reactions of buckminsterfullerene C60 with some small organic compounds in mass spectrometer

    Institute of Scientific and Technical Information of China (English)

    刘淑莹; 郭兴华; 刘子阳; 倪嘉缵

    1995-01-01

    In chemical ionization mass spectrometry (CIMS) gas phase C60+ or C60can react with fragment ions from three chloromethane and four multichloroethane molecular ions via ion-molecule reactions A dozen of gas-phase adduct ions of C60 are observed, and most of them contain chlorine atoms The results of the comparison and analysis show that the relative intensities of adduct ions are not directly proportional to the corresponding fragment ions in the MS of reagents,which implies that some fragment ions containing radicals are more reactive with C60+ or C60. This indicates that the alkene-like C60+ or C60 can act as a radical sponge in addition reactions.

  1. A New Gas Cell for High-Precision Doppler Measurements in the Near-Infrared

    CERN Document Server

    Valdivielso, L; Martín, E

    2010-01-01

    High-resolution spectroscopy in the near-infrared could become the leading method for discovering extra-solar planets around very low-mass stars and brown dwarfs. To help to achieve an accuracy of ~m/s, we are developing a gas cell which consists of a mixture of gases whose absorption spectral lines span all over the near-infrared region. We present the most promising mixture, made of acetylene, nitrous oxide, ammonia, chloromethans and hydrocarbons. The mixture is contained in a small size 13 cm long gas cell and covers most of the H and K-bands. It also shows small absorptions in the J-band but they are few and not sharp enough for near infrared wavelength calibration. We describe the working method and experiments and compare our results with the state of the art for near infrared gas cells.

  2. Production of volatile organic compounds in the culture of marine α-proteobacteria

    Science.gov (United States)

    Hirata, M.; Abe, M.; Hashimoto, S.

    2014-12-01

    Volatile organic compounds (VOCs) release halogens in the troposphere and in the stratosphere by photolysis and released halogens catalyze ozone depletion . In the ocean, macroalgae, phytoplankton, and bacteria are considered to be the main producers of VOCs. Recent investigations have shown that marine bacteria produce halomethanes such as chloromethane, bromomethane, and iodomethane. However, knowledge of aquatic VOC production, particularly through bacteria, is lacking. We studied the production of VOCs, including halomethanes, through the bacterium HKF-1. HKF-1 was isolated from brackish water in Sanaru Lake, Shizuoka prefecture, Japan. The bacterium belongs to the α-proteobacteria. Bacteria were incubated in marine broth 2216 (Difco) added with KI and KIO3 (each at 0.02 μmol/L) at 25°C. VOCs in the gas phase above the cultured samples was determined using a dynamic headspace (GESTEL DHS)—gas chromatograph (Agilent 6890N)—mass spectrometer (Agilent 5975C) at 0, 4, 7, 10 and 12 incubation days. In addition, the optical density at 600 nm (OD600) was measured during the culture period. Measurement of VOCs showed that chloromethane, bromomethane, iodomethane, isoprene, methanethiol, dimethyl sulfide, and dimethyl disulfide were produced in the culture of HKF-1. Dihalomethanes and trihalomethanes, such as dibromomethane, chloroiodomethane, bromoiodomethane, and tribromomethane, were not detected. Given that monohalomethanes and sulfur-containing VOCs were abundant in the culture, HKF-1 is one of the possible candidates as a producer of monohalomethane and sulfur-containing VOCs in marine environment, but not of di- or trihalomethanes.

  3. Organohalogen emission from saline environments – spatial extrapolation using remote sensing as most promising tool

    Directory of Open Access Journals (Sweden)

    H. F. Schöler

    2011-07-01

    Full Text Available Due to their negative water budget most recent semi-/arid regions are characterized by vast evaporates (salt lakes and salty soils. We recently identified those hyper-saline environments as additional sources for a multitude of volatile halogenated organohalogens (VOX. These compounds affect the ozone layer of the stratosphere and play a key role in the production of aerosols. A remote sensing based analysis was performed in the southern Aral Sea basin, providing information of main soil types as well as their extent and spatial and temporal evolution. VOX production has determined in dry and moist soil samples for 24 h. Several C1- and C2 organohalogens, including chloromethane and bromomethane, have been found in hyper-saline topsoil profiles. The range of naturally produced organohalogens includes dichloroethene. For the 15 000 km2 ranging research area in the southern Aralkum desert a daily production of up to 23 t dichloroethene has been calculated using MODIS time series and supervised image classification. The applied setup reproduces a short-term change in climatic conditions starting from dried-out saline soil, instantly humidified during rain events or flooding. VOX emission from dry fallen Aral Sea sediments will further increase since the area of salt affected soils is expected to increase in future. Opportunities, limits and requirements of satellite based rapid change detection and salt classification are discussed.

  4. Design and Analysis of SAW Based MEMS Gas Sensor for the Detection of Volatile Organic Gases

    Directory of Open Access Journals (Sweden)

    Staline Johnson

    2014-03-01

    Full Text Available This paper portrays the design and analysis of SAW based MEMS gas sensor for the detection of volatile organic gases. The gas sensor consists of interdigitated transducers modeled on a piezoelectric substrate and covered by a thin film of polyisobutylene (PIB which acts as the sensing layer. The piezoelectric substrate material used is YZ cut Lithium Niobate (LiNbO3 and electrodes used are made of Aluminium (Al. Mass loading effect on the sensing layer is used for the detection of volatile organic gases. The design and simultions were carried out by using comsol multiphysics software based on Finite Element Method (FEM for analytical simulations. The resonant frequency of the SAW device was determined and simulations are carried out by exposing the sensor to 100 ppm of various volatile organic gases and corresponding shift in resonant frequency for various gases are determined. The reduction in the resonant frequency is used for the detection of volatile organic gases such as chloromethane, dichloromethane, trichloromethane, tetrachloroethene, carbon tetrachloride and trichloroethylene.

  5. Triticonazole enantiomers: Separation by supercritical fluid chromatography and the effect of the chromatographic conditions.

    Science.gov (United States)

    He, Jianfeng; Fan, Jun; Yan, Yilun; Chen, Xiaodong; Wang, Tai; Zhang, Yaomou; Zhang, Weiguang

    2016-11-01

    Enantiomeric pairs of triticonazole have been successfully separated by supercritical fluid chromatography coupled with a tris(3,5-dimethylphenylcarbamoyl) cellulose-coated chiral stationary phase in this work. The effects of co-solvent, dissolution solvent, flow rate, backpressure, and column temperature have been studied in detail with respect to retention, selectivity, and resolution of triticonazole. As indicated, the co-solvents mostly affected the retention factors and resolution, due to the different molecular structure and polarity. In addition, the dissolution solvents, namely, chloromethanes and alcohols, have been also important for enantioseparation because of the different interaction with stationary phase. Higher flow rate and backpressure led to faster elution of the triticonazole molecules, and the change of column temperature showed slight effect on the resolution of triticonazole racemate. Moreover, a comparative separation experiment between supercritical fluid chromatography and high performance liquid chromatography revealed that chiral supercritical fluid chromatography gave the 3.5 times value of Rs /tR2 than high performance liquid chromatography, which demonstrated that supercritical fluid chromatography had much higher separation efficiency.

  6. Gas Phase Conversion of Carbon Tetrachloride to Alkyl Chlorides Catalyzed by Supported Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    SUN Aijun; ZHANG Jinlong; LI Chunxi; MENG Hong

    2009-01-01

    An efficient way of converting carbon tetrachloride(CTC)to alkyl chlorides is reported,which uses the catalysts of ionic liquids supported on granular active carbon.The catalytic performance was evaluated in a temperature range of 120-200℃ and atmospheric pressure for different ionic liquids,namely 1-butyl-3-methylimidazolium chloride,1-octyl-3-methylimidazolium chloride,hydrochloric salts of N-methylimidazole(MIm),pyridine and triethylamine,as well as bisulfate and dihydric phosphate of N-methylimidazole.On this basis,the reaction mechanism was proposed,and the influences of the reaction temperature and the attributes of ionic liquids were discussed.The overall reaction was assumed to be comprised of two steps,the hydrolysis of CTC and reaction of HCI with alcohols under acidic catalyst.The results indicate that the conversion of CTC increased monotonically with temperature and even approached 100% at 200 ℃,while the maximum selectivity to alkyl chlorides was obtained around 160 ℃.This reaction might be potentially applicable to the resource utilization of superfluous byproduct of CTC in the chloromethane industry.

  7. Purification and characterization of major extracellular proteinases from Trichophyton rubrum.

    Science.gov (United States)

    Asahi, M; Lindquist, R; Fukuyama, K; Apodaca, G; Epstein, W L; McKerrow, J H

    1985-11-15

    Two extracellular proteinases that probably play a central role in the metabolism and pathogenesis of the most common dermatophyte of man, Trichophyton rubrum, were purified to homogeneity. Size-exclusion chromatography and Chromatofocusing were used to purify the major proteinases 42-fold from crude fungal culture filtrate. The major enzyme has pI 7.8 and subunit Mr 44 000, but forms a dimer of Mr approx. 90 000 in the absence of reducing agents. A second enzyme with pI 6.5 and subunit Mr 36 000, was also purified. It is very similar in substrate specificity to the major enzyme but has lower specific activity, and may be an autoproteolysis product. The major proteinase has pH optimum 8, a Ca2+-dependence maximum of 1 mM, and was inhibited by serine-proteinase inhibitors, especially tetrapeptidyl chloromethane derivatives with hydrophobic residues at the P-1 site. Kinetic studies also showed that tetrapeptides containing aromatic or hydrophobic residues at P-1 were the best substrates. A kcat./Km of 27 000 M-1 X S-1 was calculated for the peptide 3-carboxypropionyl-Ala-Ala-Pro-Phe-p-nitroanilide. The enzyme has significant activity against keratin, elastin and denatured type I collagen (Azocoll).

  8. Photophysical Parameters, Excitation Energy Transfer, and Photoreactivity of 1,4-Bis(5-phenyl-2-oxazolylbenzene (POPOP Laser Dye

    Directory of Open Access Journals (Sweden)

    Samy A. El-Daly

    2012-01-01

    Full Text Available The effect of solvents on the absorption and emission spectra of 1,4-bis(5-phenyl-2-oxazolylbenzene (POPOP laser dye has been studied in various solvents at 298 K. A bathochromic shift was observed in absorption and fluorescence spectra upon increase of solvent polarity, which indicates that this transition is π-∗. The ground and excited state dipole moments were calculated as 2.23 and 6.34 Debye, respectively. The dye solution in MeOH, n-heptane, and methyl isobutyl ketone gives laser emission in the blue region upon excitation by a 337.1 nm nitrogen pulse; the gain coefficient and emission cross section as well as normalized photostability have been determined. Excitation energy transfer from POPOP to rhodamine B and fluorescine was studied to improve the laser emission from these dyes. Such an energy transfer dye laser system (ETDL obeys a long range columbic energy transfer mechanism with a critical transfer distance, R0, of 25 and 33 Å and kq equal to 10.4×1012 and 26.2×1012M−1s−1 for the POPOP/RB and POPOP/fluorescine pair, respectively. The POPOP dye is highly photostable in polar protic and polar aprotic solvents, while it displays photodecomposition in chloromethane solvent via formation of a contact ion pair. The photochemical quantum yield and rate of photodecomposition depend on the electron affinity of solvent.

  9. Wildlife ecological screening levels for inhalation of volatile organic chemicals.

    Science.gov (United States)

    Gallegos, Patricia; Lutz, Jill; Markwiese, James; Ryti, Randall; Mirenda, Rich

    2007-06-01

    For most chemicals, evaluation of ecological risk typically does not address inhalation because ingestion dominates exposure. However, burrowing ecological receptors have an increased exposure potential from inhalation at sites contaminated with volatile chemicals in the subsurface. Evaluation of ecological risk from contaminants like volatile organic chemicals (VOCs) is constrained by a lack of relevant ecological screening levels (ESLs). To address this need, inhalation ESLs were developed for 16 VOCs: Acetone, benzene, carbon tetrachloride, chloroform, chloromethane, dichlorodifluoromethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1-dichloroethene, methylene chloride, tetrachloroethene, toluene, 1,1,1-trichloroethane, trichloroethene, trichlorofluoromethane, and total xylene. These ESLs are based on Botta's pocket gopher (Thomomys bottae) as a representative fossorial receptor. The ESLs are presented with an emphasis on the process for developing inhalation toxicity reference values to illustrate the selection of suitable toxicity data and effect levels from the literature. The resulting ESLs provide a quantitative method for evaluating ecological risk of VOCs through comparison to relevant exposure data such as direct burrow-air measurements. The toxicity reference value development and ESL calculation processes and assumptions detailed here are provided as bases from which risk assessors can use or refine to suit site-specific needs with respect to toxicity and exposure inputs.

  10. The dynamics of azulene in liquids and compressed gases on ultrafast timescales

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, K.E.

    1992-02-01

    The ultrafast dynamics of vibrationally hot ground state azulene molecules have been time resolved by picosecond transient absorption spectroscopy in a variety of solvents including hexane, chloromethanes, methanol, CClF{sub 3}, Xe and Kr. A high pressure optical cell was used to liquify gases for use as solvents and change their density and temperature, independently, over the entire liquid density range. Experimental results indicate the vibrational cooling rate is strongly solvent dependent, with cooling rates of approximately 20 psec in molecular solvents and approximately 150 psec in atomic solvents. Comparison of the rates in Xe and Kr at constant density demonstrates the strong effect of solvent mass on energy transfer. The effect of solvent temperature on vibrational cooling is minimal, as is the effect of solvent density. This latter result is quite surprising in light of earlier experiments on simpler molecular systems, such as I{sub 2} in Xe. This anomalous density effect is examined in light of Isolated Binary Collision (IBC) theory and bulk thermal transport models. Both theories accurately model all experimental results obtained with the exception of the density effort. Possible explanations for the breakdown of the IBC theory in this case are offered along with methods to improve IBC theory for application to complex three dimensional molecular systems.

  11. Perchlorates are compatible with life on Earth: Why not Mars?

    Science.gov (United States)

    Kolb, Vera M.; Hoover, Richard

    2013-09-01

    Perchlorates have been found on the surface of Mars. Since they are strongly oxidizing, it is important to discuss how this fact is reflected both on the existence of organic compounds on the surface of Mars and possibly life. We have previously reported that perchlorates, although strongly oxidizing, do not destroy some amino acids, such as glycine and alanine, among others, and also spare other classes of organic compounds. Others have found that perchlorates are utilized by bacteria and Archaea as energy sources. Particularly important are the findings about Archaea, since they show a combination of a biotic and abiotic processing of perchlorates, which implies ancient origins of these pathways, which may have been typical on prebiotic Earth. There are also numerous reports of the presence of organohalogen compounds on Earth which are made by natural sources or living organisms. Such compounds may be simple, such as chloromethane, or very complicated. They are utilized or produced by living organisms on Earth. Significantly, some such compounds are extremely stable to high temperatures, over 400oC, which should be taken into account for the chemical analyses on Mars. Finally, organohalogen compounds have been also detected on the meteorites. This combined evidence indicates that eventual finding of the organohalogen compounds on Mars is expected, and that the presence of the strongly oxidizing perchlorates does not rule out life on Mars.

  12. Volatile and semivolatile organic compounds in laboratory peat fire emissions

    Science.gov (United States)

    George, Ingrid J.; Black, Robert R.; Geron, Chris D.; Aurell, Johanna; Hays, Michael D.; Preston, William T.; Gullett, Brian K.

    2016-05-01

    In this study, volatile and semi-volatile organic compound (VOCs and SVOCs) mass emission factors were determined from laboratory peat fire experiments. The peat samples originated from two National Wildlife Refuges on the coastal plain of North Carolina, U.S.A. Gas- and particle-phase organic compounds were quantified by gas chromatography-mass spectrometry and by high pressure liquid chromatography. Hazardous air pollutants (HAPs) accounted for a large fraction (∼60%) of the speciated VOC emissions from peat burning, including large contributions of acetaldehyde, formaldehyde, benzene, toluene, and chloromethane. In the fine particle mass (PM2.5), the following organic compound classes were dominant: organic acids, levoglucosan, n-alkanes, and n-alkenes. Emission factors for the organic acids in PM2.5 including n-alkanoic acids, n-alkenoic acids, n-alkanedioic acids, and aromatic acids were reported for the first time for peat burning, representing the largest fraction of organic carbon (OC) mass (11-12%) of all speciated compound classes measured in this work. Levoglucosan contributed to 2-3% of the OC mass, while methoxyphenols represented 0.2-0.3% of the OC mass on a carbon mass basis. Retene was the most abundant particulate phase polycyclic aromatic hydrocarbon (PAH). Total HAP VOC and particulate PAH emissions from a 2008 peat wildfire in North Carolina were estimated, suggesting that peat fires can contribute a large fraction of state-wide HAP emissions.

  13. Permanent gas analysis using gas chromatography with vacuum ultraviolet detection.

    Science.gov (United States)

    Bai, Ling; Smuts, Jonathan; Walsh, Phillip; Fan, Hui; Hildenbrand, Zacariah; Wong, Derek; Wetz, David; Schug, Kevin A

    2015-04-03

    The analysis of complex mixtures of permanent gases consisting of low molecular weight hydrocarbons, inert gases, and toxic species plays an increasingly important role in today's economy. A new gas chromatography detector based on vacuum ultraviolet (VUV) spectroscopy (GC-VUV), which simultaneously collects full scan (115-240 nm) VUV and UV absorption of eluting analytes, was applied to analyze mixtures of permanent gases. Sample mixtures ranged from off-gassing of decomposing Li-ion and Li-metal batteries to natural gas samples and water samples taken from private wells in close proximity to unconventional natural gas extraction. Gas chromatography separations were performed with a porous layer open tubular column. Components such as C1-C5 linear and branched hydrocarbons, water, oxygen, and nitrogen were separated and detected in natural gas and the headspace of natural gas-contaminated water samples. Of interest for the transport of lithium batteries were the detection of flammable and toxic gases, such as methane, ethylene, chloromethane, dimethyl ether, 1,3-butadiene, CS2, and methylproprionate, among others. Featured is the capability for deconvolution of co-eluting signals from different analytes.

  14. Analogue Experiments Identify Possible Precursor Compounds for Chlorohydrocarbons Detected in SAM

    Science.gov (United States)

    Miller, K.; Summons, R. E.; Eigenbrode, J. L.; Freissinet, C.; Glavin, D. P.; Martin, M. G.; Team, M.

    2013-12-01

    Since landing at Gale Crater on August 6, 2012, the Sample Analysis at Mars (SAM) instrument suite, aboard the Curiosity Rover, has conducted multiple analyses of scooped and drilled samples and has identified a suite of chlorohydrocarbons including chloromethane, dichloromethane, trichloromethane, chloromethylpropene, and chlorobenzene (Glavin et al., 2013; Leshin et al., 2013). These compounds were identified after samples were pyrolysed at temperatures up to ~835°C through a combination of Evolved Gas Analysis (EGA) and Gas Chromatography Mass Spectrometry (GCMS). Since these chlorinated species were well above the background levels determined by empty cup blanks analyzed prior to solid sample analyses, thermal degradation of oxychlorine phases, such as perchlorate, present in the Martian soil, are the most likely source of chlorine needed to generate these chlorohydrocarbons. Laboratory analogue experiments show that terrestrial organics internal to SAM, such as N-methyl-N(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA), a derivatization agent, can react with perchlorates to produce all of the chlorohydrocarbons detected by SAM. However, in pyrolysis-trap-GCMS laboratory experiments with MTBSTFA, C4 compounds are the predominant chlorohydrocarbon observed, whereas on SAM the C1 chlorohydrocarbons dominate (Glavin et al., 2013). This, in addition to the previous identification of chloromethane and dichloromethane by the 1976 Viking missions (Biemann et al., 1977), suggest that there could be another, possibly Martian, source of organic carbon contributing to the formation of the C1 chlorohydrocarbons, or other components of the solid samples analyzed by SAM are having a catalytic effect on chlorohydrocarbon generation. Laboratory analogue experiments investigated a suite of organic compounds that have the potential to accumulate on Mars (Benner et al., 2000) and thus serve as sources of carbon for the formation of chlorohydrocarbons detected by the SAM and

  15. Use of 13C Labeled Carbon Tetrachloride to Demonstrate the Transformation to Carbon Dioxide under Anaerobic Conditions in a Continuous Flow Column

    Science.gov (United States)

    Semprini, L.; Azizian, M.

    2012-12-01

    The demonstration of transformation of chlorinated aliphatic compounds (CAHs) in the subsurface is a challenge, especially when the products are carbon dioxide (CO2) and chloride ion. The groundwater contaminant carbon tetrachloride (CT) is of particular interest since a broad range of transformation products can be potentially formed under anaerobic conditions. The ability to demonstrate the transformation of CT to CO2 as a non toxic endproduct, is also of great interest. Results will be presented from a continuous flow column study where 13C labeled CT was used to demonstrate its transformation to CO2. The column was packed with a quartz sand and bioaugmented the Evanite Culture (EV) that is capable of transforming tetrachloroethene (PCE) to ethene. The column was continously fed a synthetic groundwater that was amended with PCE (0.10 mM) and either formate (1.5 mM) or lactate (1.1 mM), which ferments to produce hydrogen (H2) as the ultimate electron donor. Earlier CT transformation studies with the column, in the absence of sulfate reduction, and with formate added as a donor found CT (0.015 mM) was over 98% transformed with about 20% converted to chloroform (CF) (0.003 mM) and with a transient detection of chloromethane (CM). Methane and carbon disulfide, as potential products, were not detected. Neither CT nor CF inhibited the reductive dehalogenation of PCE to ethene. A series of transient studies conducted after these initial CT transformation tests, but in the absence of CT, showed formate remained an effective substrate for maintaining sulfate reduction and PCE transformation. Lactate, which was effectively fermented prior to CT addition, was not effectively fermented, with propionate accumulating as a fermentation product. When lactate was added, PCE was mainly transformed to cis-dichloroethene (cis-DCE) and VC, and sulfate reduction did not occur. In order to restore effective lactate fermentation the column was then bioaugmented with an EV culture that

  16. Parameters for the Pyrolysis of Organic Material - Perchlorate Mixtures

    Science.gov (United States)

    Steininger, Harald; Goesmann, Fred; Goetz, Walter

    2013-04-01

    The ESA-lead Mars rover ExoMars (launch in 2018) will carry a suit of instruments, one of the in-struments is the Mars Organic Molecule Analyzer MOMA. Organic material in the Martian soil will be either pyrolyzed at temperatures of up to 1000°C and separated by gas chromatography or volatilized with the help of an UV-laser. A mass spectrometer will be the detector for both methods. Chlorinated organics have been detected in pyroly-sis GC-MS experiments on Mars two times. The first time during the Viking mission in 1976 and a second time with the Sample Analysis on Mars (SAM) in-strument onboard the Curiosity rover in 2012. [1] [2] The presence of perchlorates found by the Phoenix mission in 2008 [3] lead to the discovery that organic molecules not only get oxidized during pyrolysis, but also chlorinated organic compounds can be pro-duced. [4] The parameters used for pyrolysis and the sample composition especially the distribution of organics and perchlorates within the sample and the concentrations of organics and perchlorate have a huge influence on the products created. It is possible to change the condi-tions of the pyrolysis by spatially separating the organ-ics from the perchlorates that the chloromethanes get the major product of the pyrolysis. This might help to understand the results of the (SAM) instrument yield-ing mono-, di- and trichloromethane and a chlorinated 4-hydrocarbon molecule. References: [1] Biemann K et al. (1977) JGR, 82, 4641-4658. [2] Grotzinger J. P et al. (2011) AGU Fall Meeting U13A-01 [3] Hecht M. H., et al. (2009) Science, 325 64-67. [4] Steininger H., Goesmann F., Goetz W. (2011) Planet. & Space Sci., 71, 9-17. Acknowledgments: This work was funded by DLR (FKZ 50QX1001)

  17. Possible Detection of Perchlorates by the Sample Analysis at Mars (SAM) Instrument: Comparison with Previous Missions

    Science.gov (United States)

    Navarro-Gonzalex, Rafael; Sutter, Brad; Archer, Doug; Ming, Doug; Eigenbrode, Jennifer; Franz, Heather; Glavin, Daniel; McAdam, Amy; Stern, Jennifer; McKay, Christopher; Coll, Patrice; Cabane, Michel; Mahaffy, Paul; Conrad, Pamela; Martin-Torres, Francisco; Zorzano-Mier, Maria; Grotzinger, John

    2013-01-01

    The first chemical analysis of soluble salts in the soil was carried out by the Phoenix Lander in the Martian Arctic [1]. Surprisingly, chlorine was present as magnesium or calcium perchlorate at 0.4 to 0.6 percent. Additional support for the identification of perchlorate came from the evolved gas analysis which detected the release of molecular oxygen at 350-550C [1]. When Mars-like soils from the Atacama Desert were spiked with magnesium perchlorate (1 percent) and heated using the Viking GC-MS protocol, nearly all the organics were combusted but a small amount was chlorinated, forming chloromethane and dichloromethane [2]. These chlorohydrocarbons were detected by the Viking GC-MS experiments when the Martian soil was analyzed but they were considered to be terrestrial contaminants [3]. Reinterpretation of the Viking results suggests trichloromethane, and chloromethylpropene) detected both by SAM QMS and GC-MS derived from known Earth organic contaminants in the instrument [6]. Calcium perchlorate appears to be the best candidate for evolved O2 in the Rocknest samples at this time but other Cl species (e.g., chlorates) are possible and must be evaluated. The potential detection of perchlorates in Rocknest material adds weight to the argument that both Viking Landers measured signatures of perchlorates. Even if the source of the organic carbon detected is still unknown, the chlorine source was likely Martian. Two mechanisms have been hypothesized for the formation of soil perchlorate: (1) Atmospheric oxidation of chlorine; and (2) UV photooxidation of chlorides catalyzed by mineral catalysts [7]. The presence of soil perchlorates in the Martian surface has important implications for the detection of organics [2], carbonates [8] and nitrates [9] by SAM.

  18. [Simultaneous determination of eight additives in polymer food packaging materials by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry].

    Science.gov (United States)

    Zhang, Xulong; Liu, Yin; Gong, Zhiguo; Wang, Pengju; Wang, Jide; Feng, Shun

    2014-08-01

    An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was proposed for the simultaneous determination of eight additives (Irgafos 168 (tri(2.4-di-tert-butylphenyl)phosphite), Irganox 1076 (octadecyl-β-(4-hydroxy-3, 5-di-tert-butylphenyl)propionate), Irganox 1010 (pentaerythritol tetrakys 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), BHA (butyl hydroxy anisole), TBHQ (tertiary butylhydroquinone), PG (propyl gallate), DG (dodecyl gallate), UV-326 (2-( 2'-hydroxyl-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole) in food packaging materials. After extracted by chloromethane through ultrasonic extraction, the samples were analyzed by UPLC-MS/MS. The chromatographic conditions were optimized, and the best separation was obtained on a Waters BEH-C18 column (50 mm x 2. 1 mm, 1.7 μm) with gradient elution of 0. 05% acetic acid solu- tion and methanol. The analysis was performed by UPLC-MS/MS with electrospray ionization (ESI) source in switching between the positive and negative ion modes in one run for multiple reaction monitoring. The eight additives showed good linear relationships in the ranges with all the correlation coefficients (R2) more than 0. 993. The limits of detection (LODs, S/N= 3) and limits of quantitation (LOQs, S/N= 10) of this method were 0. 13-5.50 μg/L and 0.45-17.50 μg/L, respectively. The recoveries were in the range of 63. 9% - 127. 0% with all the RSDs food packaging materials.

  19. Evaluated Enthalpies of Formation of the Stable Closed Shell C1 and C2 Chlorinated Hydrocarbons

    Science.gov (United States)

    Manion, Jeffrey A.

    2002-03-01

    Experimental data on the enthalpies of formation of chloromethanes, chloroethynes, chloroethenes, and chloroethanes are critically reviewed. Enthalpy of formation values for the C1 and C2 chlorinated hydrocarbons are highly cross-linked by various measured reaction equilibria and currently available sets of values are not internally self-consistent. It is shown that the early static bomb combustion calorimetry studies on highly chlorinated compounds generally give enthalpies of formation that are systematically more positive than later values derivable from rotating bomb combustion or equilibria studies. Those previously recommended values which were based mainly on the early static bomb work therefore need substantial revision. On the basis of more recent literature data obtained with rotating bomb combustion calorimetry, together with analyses of literature data on other reaction enthalpies and equilibria involving chlorinated hydrocarbons, an updated self-consistent set of ΔfHo[298.15 K] values for closed shell chlorinated C1 and C2 hydrocarbons (25 compounds) is recommended. Data on the enthalpies of vaporization are also reviewed and values of ΔvapH[298.15 K] and ΔvapHo[298.15 K] are recommended. The presently suggested enthalpies of formation for highly chlorinated alkenes and alkanes (particularly C2Cl4, C2HCl3, C2HCl5, and C2Cl6) are significantly (8-15 kJ mol-1) more negative than given by most previous evaluators. Values for the chloroethynes are 10-25 kJ mol-1 more positive than given in previous reviews and more limited changes are suggested for other compounds in the series.

  20. Ozone-depleting substances and the greenhouse gases HFCs, PFCs and SF6. Danish consumption and emissions, 2004

    Energy Technology Data Exchange (ETDEWEB)

    Sander Poulsen, T. [PlanMiljoe (Denmark)

    2006-05-19

    The objective of this project was to map the 2004 consumption of newly produced industrial ozone-depleting substances and the consumption and actual emissions of HFCs, PFCs, and SF6. The evaluation was made in accordance with the IPCC guidelines, and following the method employed in previous evaluations and it covers the net consumption of ozone-depleting substances. The term 'net consumption' is understood as the amount of imported goods in bulk or drums, less any re-export of substances as raw materials. Ozone-depleting substances contained in finished products that are imported and exported are not included in the evaluation. This delimitation is in full compliance with international guidelines. The evaluation does not account for the consumption of ozone-depleting substances used as raw material in the production of other substances, such as tetra chloromethane, and which are not subsequently emitted to the atmosphere. The information on consumption has been gathered from importers, suppliers and enterprise end-users (usually purchasing departments), and Statistics Denmark. This method of data gathering means that the information gathered is about the quantities of substances traded. Purchase and sales figures are used as an expression of consumption. This approach is considered to be suitable and adequate for the present purpose, since experience from previous projects shows that a levelling out occurs with time and that the substances sold/purchased are consumed within a relatively small time horizon. None of the substances covered here are produced in Denmark. Furthermore, ozone-depleting substances are treated at chemical waste processing plants in Denmark. Treatment and destruction data was gathered for the evaluation, but in line with all previous evaluations it has not been accounted for in the consumption figures. (BA)

  1. Potential precursor compounds for chlorohydrocarbons detected in Gale Crater, Mars, by the SAM instrument suite on the Curiosity Rover

    Science.gov (United States)

    Miller, Kristen E.; Eigenbrode, Jennifer L.; Freissinet, Caroline; Glavin, Daniel P.; Kotrc, Benjamin; Francois, Pascaline; Summons, Roger E.

    2016-03-01

    The detection of chlorinated organic compounds in near-surface sedimentary rocks by the Sample Analysis at Mars (SAM) instrument suite aboard the Mars Science Laboratory Curiosity rover represents an important step toward characterizing habitable environments on Mars. However, this discovery also raises questions about the identity and source of their precursor compounds and the processes by which they become chlorinated. Here we present the results of analog experiments, conducted under conditions similar to SAM gas chromatography-mass spectrometry analyses, in which we pyrolyzed potential precursor compounds in the presence of various Cl salts and Fe oxides that have been identified in Martian sediments. While chloromethanes could not be unambiguously identified, 1,2-dichloropropane (1,2-DCP), which is one of the chlorinated compounds identified in SAM data, is formed from the chlorination of aliphatic precursors. Additionally, propanol produced more 1,2-DCP than nonfunctionalized aliphatics such as propane or hexanes. Chlorinated benzenes ranging from chlorobenzene to hexachlorobenzene were identified in experiments with benzene carboxylic acids but not with benzene or toluene. Lastly, the distribution of chlorinated benzenes depended on both the substrate species and the nature and concentration of the Cl salt. Ca and Mg perchlorate, both of which release O2 in addition to Cl2 and HCl upon pyrolysis, formed less chlorobenzene relative to the sum of all chlorinated benzenes than in experiments with ferric chloride. FeCl3, a Lewis acid, catalyzes chlorination but does not aid combustion. Accordingly, both the precursor chemistry and sample mineralogy exert important controls on the distribution of chlorinated organics.

  2. Influence of Oxychlorine Phases During the Pyrolysis of Organic Molecules: Implications for the Quest of Organics on Mars with the SAM Experiment Onboard the Curiosity Rover

    Science.gov (United States)

    Millan, M.; Szopa, C.; Buch, A.; Belmahdi, I.; Glavin, D. P.; Freissinet, C.; Eigenbrode, J. L.; Archer, P. D., Jr,; Sutter, B.; Mahaffy, P.

    2017-01-01

    One among the main objectives of the Sample Analysis at Mars (SAM) experiment is the in situ molecular analysis of gases evolving from solid samples heated up to approximately 850 degrees Centigrade, and collected by Curiosity on Mars surface/sub-surface in Gale crater. With this aim, SAM uses a gas-chromatograph coupled to a quadrupole mass spectrometer (GC-QMS) devoted to separate, detect and identify both volatile inorganic and organic compounds. SAM detected chlorinated organic molecules produced in evolved gas analysis (EGA) experiments. Several of these were also detected by the Viking experiments in 1976. SAM also detected oxychlorine compounds that were present at the Phoenix landing site. The oxychlorines may be prevelant over much of the martian surface. The C1 to C3 aliphatic chlorohydrocarbons (chloromethane and di- and trichloromethane) detected by SAM were attributed to reaction products occurring between the oxychlorines phases and the organic compounds coming from SAM instrument background. But SAM also showed the presence of a large excess of chlorobenzene and C2 to C4 dichloroalkanes among the volatile species released by the Cumberland sample of the Sheepbed mudstone. For the first time in the history of the Mars exploration, this proved the presence of Mars indigenous organic material at the Mars' surface. However, the identification of the precursor organic compounds of these chlorohydrocarbons is difficult due to the complexity of the reactions occurring during the sample pyrolysis. Laboratory pyrolysis experiments have demonstrated that oxychlorines phases such as perchlorates and chlorates, decomposed into dioxygen and volatile chlorine bearing molecules (HCl and/or Cl2) during the pyrolysis. These chemical species can then react with the organic molecules present in the martian solid samples through oxidation, chlorination and oxychlorination processes.

  3. The spontaneous combustion of coal and its by-products in the Witbank and Sasolburg coalfields of South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Pone, J. Denis N. [Energy and Geo-Environmental Engineering, The Pennsylvania State University, 228 Housler Building, University Park, PA 16802 (United States); Hein, Kim A.A. [School of Geosciences, University of the Witwatersrand Johannesburg, P/Bag 3, 2050, WITS (South Africa); Stracher, Glenn B. [Division of Science and Mathematics, East Georgia College, Swainsboro, Georgia 30401 (United States); Annegarn, Harold J. [Department of Geography and Environmental Management, University of Johannesburg, P.O. Box 524, Auckland Park, 2006 (South Africa); Finkleman, Robert B. [University of Texas at Dallas, Department of Geosciences, Richardson, TX 75083-0688 (United States); Blake, Donald R. [Department of Chemistry, 570 Rowland Hall, University of California, Irvine, CA 92697-2025 (United States); McCormack, John K. [Electron Microbeam Facility, Department of Geological Sciences, MS 172, Mackay School of Mines, University of Nevada, Reno, Navada 8955-0047 (United States); Schroeder, Paul [Department of Geology, University of Georgia, 210 Field Street, Athens, GA 30602-2501 (United States)

    2007-10-01

    Spontaneous combustion of coal seams in the Witbank and Sasolburg coalfields, South Africa, was studied in order to determine if toxic chemical elements and compounds are being mobilised into the environment. Samples of the minerals forming on the surface of coal seams, and gases escaping from vents, were analysed to verify the presence of these elements and compounds. Gas temperature measurements at coal-fire vents range from 34 C to 630 C. The coal-fire gas minerals (CFGM) identified included sulphur compounds and salammoniac. X-ray diffraction (XRD) studies of CFGM by-products confirmed the presence of mascagnite ((NH{sub 4}){sub 2}SO{sub 4}), illite ((Al,Si){sub 4}O{sub 10}[(OH){sub 2},H{sub 2}O]) letovicite ((NH{sub 4}){sub 3}H(SO{sub 4}){sub 2}), phlogopite (KMg{sub 3}(AlSi{sub 3})O{sub 10}(F,OH){sub 2}), titanium dioxide (TiO{sub 2}), barite (BaSO{sub 4}), iron sulphate (FeSO{sub 4}), gypsum (CaSO{sub 4}.2H{sub 2}O) and silicate. An unknown and unclassified sulphur-nitrogen-chlorine CFGM was also identified. The minerals are interpreted to have formed by condensation or sublimation; several may be alteration products. Other heavy elements found in the CFGM's are mercury, arsenic, lead, zinc, and copper. Arsenic and mercury were the major elements of potential environmental significance found accumulating around coal-fire vents. Relatively high concentrations of toluene, benzene and xylene were found in the gas collected at both Witbank and Sasolburg coalfields. Benzene, toluene and xylenes are known to possess carcinogenic proprieties. Thirty-two aliphatic compounds were detected, as well as halogenated compounds including bromomethane, iodomethane and trichloromethane in low concentrations, and dichloromethane and chloromethane in high concentrations. The highest concentrations of halogenated compounds were measured for gas samples from the Witbank coalfield. High concentrations of carbon monoxide, carbon dioxide, and methane were also detected. The

  4. Thermal Reactivity of Organic Molecules in the Presence of Chlorates and Perchlorates and the Quest for Organics on Mars with the SAM Experiment Onboard the Curiostiy Rover

    Science.gov (United States)

    Szopa, Cyril; Millan, Maeva; Buch, Arnaud; Belmahdi, Imene; Coll, Patrice; Glavin, Daniel P.; Freissinet, Caroline; Eigenbrode, Jennifer; archer, doug; sutter, brad; Summons, Roger; Navarro-Gonzalez, Rafael; Mahaffy, Paul; cabane, Michel

    2016-10-01

    One of the main objectives of the Sample Analysis at Mars (SAM) experiment is the in situ molecular analysis of gases evolving from solid samples collected by Curiosity when they are heated up to ~850°C. With this aim SAM uses a gas-chromatograph coupled to a mass spectrometer (GC-MS) able to detect and identify both inorganic and organic molecules released by the samples.During the pyrolysis, chemical reactions occur between oxychlorines, probably homogeneously distributed at Mars's surface, and organic compounds SAM seeks for. This was confirmed by the first chlorohydrocarbons (chloromethane and di- and trichloromethane) detected by SAM that were entirely attributed to reaction products occurring between these oxychlorines and organics from instrument background. But SAM also detected in the Sheepbed mudstone of Gale crater, chloroalkanes produced by reaction between oxychlorines and Mars indigenous organics, proving for the first time the presence of organics in the soil of Mars. However, the identification of the molecules at the origin of these chloroalkanes is much more difficult due to the complexity of the reactivity occurring during the sample pyrolysis. If a first study has already been done recently with this aim, it was relatively limited in terms of parameters investigated.This is the reason why, we performed a systematic study in the laboratory to help understanding the influence of oxychlorines on organic matter during pyrolysis. With this aim, different organic compounds from various chemical families (e.g. amino and carboxylic acids) mixed with different perchlorates and chlorates, in concentrations compatible with the Mars soil from estimations done with SAM measurements, were pyrolyzed under SAM like conditions. The products of reaction were analyzed and identified by GC-MS in order to show a possible correlation between them and the parent molecule. Different parameters were tested for the pyrolysis to evaluate their potential influence on the

  5. 气相色谱-质谱法测定海水及水产品中的莠去津%Determination of atrazine in seawater and sea food by gas chromatohraph- mass spectrum

    Institute of Scientific and Technical Information of China (English)

    吴茂生

    2012-01-01

    本文采用有机溶剂萃取的提取方法,利用气相色谱一质谱选择离子检测,建立了海水及水产品中莠去津的检测方法。该方法在0.001-0.5μg/L的范围内具有良好的线性范围,线性相关系数为0.9996;在海水和水产品中的检出限(S/N=3)分别为0.001μg/L和0.001mg/kg;在加标回收率试验中,海水中莠去津回收率为95.8%-113.2%,水产品中莠去津回收率为83.1%~92.6%;相对标准偏差(n=6)均小于4.4%。%A gas chromatohraph - mass spectrum method was established for determination of atrazine in sea- water and sea food. The pretreatment and chromatographic conditions were optimized. The total of 50 mL di- chloromethane was chosen in the process of organic solvent - seawater extract with liquid - liquid extraction technique. Florisil SPE column and hexane mixed with ethyl acetate were used to clean up the sea food sample so as to reduce continuum organic interference in Ionization mode (EI) using select ion monitori obtained for atrazine in the range of 0. 001 -0. ng 5 GC -MS detection. Identification was achieved by Electron (SIM). Under the optimal conditions, good linearities were μg/L. The quantification was performed with internal stand- ards. The recoveries of atrazine in seawater and sea food were in the range of 95.8% - 113.2% and 83.1% -92.6% respectively. The relative standard deviations (RSD) were less than 4.4%. The limits of detection were 0. 001 μg/L for atrazine in seawater, and 0 successfully applied to determination of atrazine in an accident 001 mg/kg for atrazine in sea food. The method has been seawater and sea food in sea area of Fujian province during

  6. Determination of volatile halohydrocarbons in drinking water by capillary column gas chromatography%毛细管柱气相色谱法测定生活饮用水中挥发性卤代烃

    Institute of Scientific and Technical Information of China (English)

    董玉英; 张瑞雨; 欧利华

    2013-01-01

    Objective: To establish a method for determination of seven volatile halohydrocarbons in drinking water. Methods: The seven volatile halohydrocarbons (chlorofrom, tetrachloromethane, trichloroethylene, bromodi-chloromethane, tetrachloroethylene, dibromochloromethane, bromoform) in drinking water were determined by head-space Gas Chromatography with DB - 624 capillary column. Results: Under the optimal experimental conditions, the recoveries of the seven volatile halohydrocarbons were in the range of 92.5% -102%, the relative standard deviation was between 1.20% ~4.61%, and the determination limit was between 0.01 μg/L ~ 1.00 μg/L. Conclusion: The developed methjod is sensitive, simple, rapid and accurate, and seven volatile halohydrocarbons in drinking water can be determined simultaneously.%目的:建立一种快速、准确测定生活饮用水中7种挥发性卤代烃的方法.方法:采用DB-624毛细管柱、顶空气相色谱法测定生活饮用水中三氯甲烷、四氯化碳、三氯乙烯、二氯一溴甲烷、四氯乙烯、一氯二溴甲烷及三溴甲烷.结果:在所选择的实验条件下,7种挥发性卤代烃的平均回收率在92.5%~102%之间,相对标准偏差(RSD)为1.20% ~4.61%,检出限为0.01 μg/L ~1.00 μg/L.结论:所建立的分析方法灵敏、简便、快速、准确,可同时测定生活饮用水中的7种挥发性卤代烃.

  7. Comparison of Different Extraction Methods on Pretreatment of Levonorgestrel Containing Water%左炔诺孕酮不同萃取剂萃取能力比较

    Institute of Scientific and Technical Information of China (English)

    翟俊; 荣婧; 占宏; 宁可佳; 阮雨

    2011-01-01

    比较了液液萃取和固相萃取两种方法对左炔诺孕酮的萃取效果,为含左炔诺孕酮水样分析预处理提供参考.运用高效液相色谱法检测了二氯甲烷、三氯甲烷、正己烷、乙酸乙酯4种有机溶剂和StrataTM-X(60 mg,3mL)固相萃取柱对左炔诺孕酮的萃取回收率;萃取回收率分别为:乙酸乙酯(97.22%)>二氯甲烷(91.89%)>正己烷(91.67%)>三氯甲烷( 91.33%)>StrataTM-X柱(87.11%),对应的相对标准差分别为1.05%、3.29%、2.75%、3.48%、0.97%.试验结果表明:液液萃取法整体萃取回收率要高于周相萃取法,其中乙酸乙酯的萃取回收率为最优.相对标准差值的比较表明固相萃取法的稳定性高于液液萃取.%Extraction efficiencies of levonorgestrel were compared when using liquid-liquid phase extraction and solid -phase extraction, which provided references for levonorgestrel sample pre-treatment. The recovery rates of levonorgestrel extracted with four different liquid organic solvents including dichloromethane, chloroform, hexane, ethyl, and one solid-phase extraction column, StrataTM-X (60 mg,3 mL) were analyzed with the quantity detection of high performance liquid chromatography method. The recovery rates were listed in an order of ethyl (97.22%)>dichloromethane (91.89%)> hexane (91.67%)>chloromethane (91.33%)>StrataTM-Xcolumn (87.11%), with relative standard deviations 1.05%,3.29%, 2.75% ,3.48% ,0.97% respectively. Experiment results indicated that liquid-liquid phase extraction method had a higher recovery rate than solid-phase extraction method. The results of relative standard deviation showed that solid-phase extraction is more stable than liquid-liquid phase extraction.

  8. Measurements of reactive chlorocarbons over the Surinam tropical rain forest: indications for strong biogenic emissions

    Directory of Open Access Journals (Sweden)

    H. A. Scheeren

    2003-10-01

    Full Text Available Contrary to the understanding of the emissions and chemical behavior of halocarbons from anthropogenic sources (e.g. CFCs and HCFCs, the biogeochemistry of naturally emitted halocarbons is still poorly understood. We present measurements of chloromethane (methyl chloride, CH3Cl, trichloromethane (chloroform, CHCl3, dichloromethane (CH2Cl2, and tetrachloroethylene (C2Cl4 from air samples taken over the Surinam rainforest during the 1998 LBA/CLAIRE campaign. The samples were collected in stainless steel canisters on-board a Cessna Citation jet aircraft and analyzed in the laboratory using a gas chromatograph equipped with FID and ECD. The chlorocarbons we studied have atmospheric lifetimes of ~1 year or less, and appear to have significant emissions from natural sources including oceans, soils and vegetations, as well as biomass burning. These sources are primarily concentrated in the tropics (30º N-30º S. We detected an increase as a function of latitude of methyl chloride, chloroform, and tetrachloroethylene mixing ratios, in pristine air masses advected from the Atlantic Ocean toward the central Amazon. In the absence of significant biomass burning sources, we attribute this increase to biogenic emissions from the Surinam rainforest. From our measurements, we deduce fluxes from the Surinam rainforest of 7.6±1.8 μg CH3Cl m−2 h−1, 1.11±0.08g CHCl3 μm−2 h−1, and 0.36±0.07 μg C2Cl4 m−2 h−1. Extrapolated to a global scale, our emission estimates suggest a large potential source of 2 Tg CH3Cl yr−1 from tropical forests, which could account for the net budget discrepancy (underestimation of sources, as indicated previously. In addition, our estimates suggest a potential emission of 57±17,Gg C2C4 yr−1

  9. Simultaneous anaerobic transformation of tetrachloroethene and carbon tetrachloride in a continuous flow column

    Science.gov (United States)

    Azizian, Mohammad F.; Semprini, Lewis

    2016-07-01

    Tetrachloroethene (PCE) and carbon tetrachloride (CT) were simultaneously transformed in a packed column that was bioaugmented with the Evanite culture (EV). The data presented here have been obtained over a period of 1930 days. Initially the column was continuously fed synthetic groundwater with PCE (0.1 mM), sulfate (SO42 -) (0.2 mM) and formate (2.1 mM) or lactate (1.1 mM), but not CT. In these early stages of the study the effluent H2 concentrations ranged from 7 to 19 nM, and PCE was transformed to ethene (ETH) (81 to 85%) and vinyl chloride (VC) (11 to 17%), and SO42 - was completely reduced when using either lactate or formate as electron donors. SO42 - reduction occurred concurrently with cis-DCE and VC dehalogenation. Formate was a more effective substrate for promoting dehalogenation based on electron donor utilization efficiency. Simultaneous PCE and CT tests found CT (0.015 mM) was completely transformed with 20% observed as chloroform (CF) and trace amounts of chloromethane (CM) and dichloromethane (DCM), but no methane (CH4) or carbon disulfide (CS2). PCE transformation to ETH improved with CT addition in response to increases in H2 concentrations to 160 nM that resulted from acetate formation being inhibited by either CT or CF. Lactate fermentation was negatively impacted after CT transformation tests, with propionate accumulating, and H2 concentrations being reduced to below 1 nM. Under these conditions both SO42 - reduction and dehalogenation were negatively impacted, with sulfate reduction not occurring and PCE being transformed to cis-dichloroethene (c-DCE) (52%) and VC (41%). Upon switching to formate, H2 concentrations increased to 40 nM, and complete SO42 - reduction was achieved, while PCE was transformed to ETH (98%) and VC (1%), with no acetate detected. Throughout the study PCE dehalogenation to ethene was positively correlated with the effluent H2 concentrations.

  10. Physical and physicochemical factors effecting transport of chlorohydrocarbon gases from lung alveolar air to blood as measured by the causation of narcosis.

    Science.gov (United States)

    Holder, James W

    2012-01-01

    This systematic investigation examines gas transport in the lung for two sets of chlorohydrocarbons (CHCs): the chloromethanes (C1) and chloroethanes (C2). The C1 series includes chloromethane, methylene chloride, chloroform, and carbon tetrachloride, and the C2 series includes chloroethane, 1,2-dichloroethane, 1, 1, 2-trichloroethane, and 1, 1, 2, 2-tetrachloroethane. Most CHC gases cause narcosis. The comprehensive narcosis work of Lehmann and colleagues on CHCs was used as a basis for the narcosis endpoint in the present examination. The sites for narcosis are located in the brain (midline cortex and posterior parietal area), the spine, and at many peripheral nerve sites. Central nervous system (CNS) exposure executes a multisite, neural transmission set of inhibitions that promotes rapid loss of consciousness, sensory feeling, and current and stored memory while providing temporary amnesia. Absorption into the system requires dissolution into many lipid membranes and binding to lipoproteins. Lipophilicity is a CHC property shared with many anesthetics according to the Meyer-Overton Rule. Many structurally different lipid chemicals produce the narcosis response when the lipid concentration exceeds -67 mM. This suggests narcotic or anesthetic dissolution into CNS membranes until the lipid organization is disrupted or perturbed. This perturbation includes loading of Na(+)- and K(+)-channel transmembrane lipoprotein complexes and disrupting their respective channel functional organizations. The channel functions become attenuated or abrogated until the CHC exposure ceases and CHC loading reverses. This investigation demonstrates how the CHC physical and chemical properties influence the absorption of these CHCs via the lung and the alveolar system on route to the blood. Narcosis in test animals was used here as an objective biological endpoint to study the effects of the physical factors Bp, Vp, Kd (oil: gas) partition, Henry's constant (HK), and water solubility

  11. Determination of dichloromethane and trichloromethane residues in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chromatography%顶空液相微萃取-气相色谱法测定盐酸雷尼替丁中二氯甲烷和三氯甲烷的残留量

    Institute of Scientific and Technical Information of China (English)

    申书昌; 云丹; 李飞

    2009-01-01

    A method for the determination of residual dichloromethane and trichloromethane in ranitidine hydrochloride by headspace liquid phase microextraction coupled with gas chroma-tography (GC) was developed. A homemade device was used to protect the organic drop. The effects of the nature of extraction solvent, extraction time, extraction temperature and micro-drop volume on the extraction efficiency were investigated separately. The optimal experimen-tal conditions were as follows:2 ΜL of n-tridecane as extraction solvent, 30 min of extraction time, 60 ℃ of extraction temperature. The correlation coefficients of linear calibration curve were 0. 973 3 and 0. 972 4 within the concentration ranges of dichloromethane (1-10 μg/g) and trichloromethane (1-10 μg/g), respectively. The detection limits of dichlormethane and tri-chloromethane were 0. 027 3 μg/g and 0. 041 0 μg/g, respectively, the relative standard devia-tions were lower than 4. 36% and 5. 89%, and the recoveries of the method were 93. 6% - 102% and 98.1% -103%, respectively. The method is simple and reliable.%采用顶空液相微萃取与气相色谱联用技术测定雷尼替丁中二氯甲烷和三氯甲烷的残留量.自制了萃取液保护装置.考察了萃取溶剂的种类、萃取时间、萃取温度、萃取液的体积对二氯甲烷和三氯甲烷萃取效果的影响.以正十三烷为萃取剂,在60 ℃下萃取30 min,萃取液滴体积2 μL.二氯甲烷含量在1~10 μg/g范围内与色谱峰高呈线性关系,相关系数(r~2)为 0.973 3;三氯甲烷含量在1~10 μg/g范围内与色谱峰高呈线性关系,r~2为 0.972 4.二氯甲烷和三氯甲烷的最低检出限分别为 0.027 3 μg/g和 0.041 0 μg/g,加标回收率分别为93.6% ~102%和98.1% ~103% .方法简便易行,测定结果准确.

  12. Organic carbon compounds detected by the SAM instrument suite on Curiosity: results of the first year of exploration at Gale Crater (Invited)

    Science.gov (United States)

    Summons, R. E.; Miller, K.; Glavin, D. P.; Eigenbrode, J. L.; Freissinet, C.; Martin, M. G.; Team, M.

    2013-12-01

    A search for organic matter is a high priority in the search for habitable environments on Mars as it is in the quest for clues about the nature of early life on Earth. These endeavors are technically challenging because of the inherent instability of organic matter under conditions that exist in the regolith of both planets and the antiquity of the sediments of interest. In the case of the early Earth, exposure to ionizing radiation and the heat associated with burial and tectonism are the main obstacles to organic matter preservation. On Mars, exposure to ionizing radiation and chemical oxidation are the prime threats to organic matter preservation. It has been hypothesized that UV-generated hydroxyl radicals will almost certainly oxidize or highly alter any organic carbon of martian or meteoritic origin at Mars' surface. Also, there could be diagenetic processes peculiar to Mars, for which no terrestrial analogs are presently known. Thus, the search for organics on Mars must be informed by data from the entire Curiosity payload since the results are mutually informative. Sediments from the Rocknest aeolian drift and the probable fluvio-lacustrine sediments of Yellowknife Bay in Gale Crater, when analyzed by pyrolysis with evolved gas analysis (EGA) and gas chromatography mass spectrometry (GC-MS), afforded a number of chlorohydrocarbons including chloromethane, dichloromethane, trichloromethane, a chloromethylpropene, and chlorobenzene (1, 2). Some proportion of these compounds can be traced to instrument background from organic materials within the chromatographic columns, hydrocarbon traps and wet chemistry capability of SAM. N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide, compounds carried in SAM for chemical derivatization can react with gases released from the sediments to yield the C1 and C4 chlorohydrocarbons. However, we continue to explore the possibility that a portion of the C1 chlorohydrocarbons are derived

  13. A Continuous Flow Column Study of the Anaerobic Transformation of a CAH Mixture of Tetrachloroethene and Carbon Tetrachloride Using Formate as an Electron Donor

    Science.gov (United States)

    Semprini, L.; Azizian, M. F.; Kim, Y.

    2011-12-01

    Many groundwater sites are contaminated with mixtures of chlorinated aliphatic hydrocarbons (CAHs) that represent a challenge when biological remediation processes are being considered. This is especially challenging when high concentrations of CAHs are present.Trichloromethane (CF), for example, has been observed to inhibit and potentially exert toxicity on reductive dehalogenation of tetrachloroethene (PCE) and trichloroethene (TCE). Results will be presented from a continuous flow column study where the simultaneous transformation of PCE and carbon tetrachloride (CT) was achieved. The column was packed with a quartz sand and bioaugmented with the Evanite Culture (EV) that is capable of transforming PCE to ethene. The column was fed a synthetic groundwater that was amended with PCE to achieve an influent concentration near its solubility limit (0.10 mM) and formate (1.5 mM) that reacts to produce hydrogen as the ultimate electron donor. The column was operated for over 1600 days prior to the addition of CT. During this period PCE was transformed mainly to vinyl chloride (VC) and ethene (ETH) and minor amounts of cis-dichloroethene (cis-DCE) and TCE. The transformation extent achieved based on the column effluent concentrations ranged from about 50% ETH, 30% VC, and 20 cis-DCE up to 80% ETH and 20% VC. When the column was fed sulfate, it was completely transformed via sulfate reduction. Ferrous iron production from ferric iron reduction was observed early in the study. Acetate was also formed as a result of homoacetogenesis from hydrogen utilization. CT addition (0.015 mM) was started at 1600 days while PCE addition was continued. During the first 25 days of CT addition, CT concentrations gradually increased to 50% of the injection concentration and chloromethane (CM) and CF were observed as transformation products. CT concentrations then decreased with over 98% transformation achieved.CM was removed to below the detection limit and CF concentration decreases to

  14. Comparison of detection methods of total lipid content in microalgae%微藻油脂含量不同测定方法的比较研究

    Institute of Scientific and Technical Information of China (English)

    彭悦; 刘玉莹; 祁艳霞; 胡玉才; 付晚涛

    2015-01-01

    为了对微藻油脂含量不同测定方法进行比较,以球等鞭金藻8701 Isochrysis galbana Parke 8701和小新月菱形藻Nitzschia closterium f. minutissima两种微藻为研究对象,采用溶剂提取法和苏丹黑B染色法对其油脂含量进行测定,建立了两种微藻油脂含量与苏丹黑染色后吸光度A645 nm的线性回归方程,并应用于微藻油脂积累培养过程的快速测定,利用气相色谱法对两种微藻脂肪酸组成进行分析。结果表明:当提取溶剂为二氯甲烷和甲醇的混合溶剂(二者的体积比为1:2)时,油脂提取效果较好,得到球等鞭金藻8701和小新月菱形藻的油脂含量分别为22.99%和16.89%;采用苏丹黑B染色法测定的油脂含量基本和生物量大体一致,是一种可行的估测油脂含量的方法;气相色谱检测结果显示,两种微藻具有明显不同的脂肪酸组成特征,球等鞭金藻8701的饱和脂肪酸含量(55.02%)较小新月菱形藻(51.39%)高。研究表明,从两种微藻的油脂含量和脂肪酸组成来看,球等鞭金藻8701较小新月菱形藻更适用于作为生物柴油的原料。%The total lipid contents were analyzed by methods of organic solvents and Sudan black B staining in two species of microalgae, Isochrysis galbana Parke 8701 and Nitzschia closterium f. minutissima. linear regression e-quations were established between lipid contents and absorbance at a wavelength of 645 nm. It was found that mi-croalgae cells were stained with Sudan black B, and applied to rapid determination of the microalgae oil accumula-tion rapidly. Fatty acid compositions were also analyzed by gas chromatography ( GC) . The extraction of solvent di-chloromethane/methanol ( volume ratio =1:2 ) revealed that there was total lipid content of 22 . 99% in Isochrysis galbana Parke 8701, and 16. 89% in Nitzschia closterium f. minutissima. The total lipid was consistent with the bi-omass by Sudan black B staining method

  15. EXTRACTIVE DISTILLATION PROCESS SIMULATION FOR SEPARATION OF DICHLOROMETHANE AND ACETONE%萃取精馏分离二氯甲烷-丙酮的工艺模拟

    Institute of Scientific and Technical Information of China (English)

    王震; 高晓冲; 夏庆宁; 高瑞昶

    2012-01-01

    Dichloromethane and acetone can form the highest azeotrope, so it can not be separated by conventional distillation. Extractive distillation for separation of dichloromethane and acetone was simulated by computer. Wilson model and NRTL model were used for predicting VLE and LLE. The influence of operation factors such as stage number, reflux ratio, extractant feed rate, location, temperature and material feed location, temperature were analyzed. The optimal parameters of column were proposed: the theoretical total plate number of extraction column is 36, the reflux ratio is 3, the raw material is fed at 16th plate, the extractant is fed at 7th plate and the feed rate is 1 500 kg/h. Di-chloromethane-water azeotrope was obtained at the top of the extraction column. The dichloromethane layer was 99. 9%. Acetone-water mixture which was obtained at the bottom of extraction column was put into the acetone column, the theoretical total plate number of acetone column is 35, the reflux ratio is 4, and the raw material is fed at 25th plate. A top product of acetone with 99. 7% concentration and a bottom product of almost pure water which can be recycled as extraction water after cooling could be obtained. These results are useful for construction design and improvement.%以水为萃取剂对二氯甲烷丙酮混合物进行了萃取精馏过程模拟,体系的气-液平衡和液液平衡分别采用Wilson模型和NRTL模型预测.分析了总理论板数,回流比,萃取剂进料速率、塔板数、温度和原料进料塔板数、温度等操作参数对精馏过程的影响.并取得了最佳工艺参数为:萃取塔采用36块理论板,回流比为3,原料在第16块板进料,萃取剂用量1 500 kg/h,第7块板进料时塔顶得到二氯甲烷-水的共沸物,分层得99.9%的二氯甲烷,塔釜得到丙酮-水的混合物进入丙酮塔;丙酮塔为简单精馏塔,采用35块理论板,回流比为4,第25块板进料,塔顶可得99.7%的丙酮,塔釜得到几乎

  16. Highly electrophilic organometallics for carbocationic polymerizations: from anion engineering to new polymer materials.

    Science.gov (United States)

    Bochmann, Manfred

    2010-09-21

    Ion-ion interactions are a crucial but often overlooked aspect of many polymerization reactions. The precise nature of cation-anion binding is as yet poorly understood, and little is known of the extent of ionic interactions in the typically nonaqueous, low-polarity reaction media of most polymerizations. Nevertheless, adequate control of cation-anion interactions can greatly enhance the productivity and efficiency of chemical processes and can provide low-energy alternatives to current methods. This is illustrated here with the carbocationic polymerization of isoalkenes. Carbocationic polymerizations involve, as the name implies, carbocations as propagating species. Of the various types of substrates that can be polymerized cationically, the copolymerization of isobutene to isobutene-isoprene rubber stands out as the only large-scale, industrially important implementation of this reaction type. The products, elastomers with controlled degrees of unsaturation for subsequent cross-linking, have excellent gas barrier and mechanical dampening properties that make them indispensable components in polymer composites. For such applications, the polymer molecular weight has to be high, ∼5 × 10(5) g/mol, with 1-2 mol % isoprene. Cationic polymerizations are however notoriously difficult to control. As a means of suppressing chain transfer, the process is carried out at temperatures as low as -100 °C, with aluminum chloride initiators in chloromethane. Current industrial production of isobutene-isoprene butyl rubber is thus highly energy intensive and produces aluminum and chloride effluent. This Account summarizes how highly electrophilic organometallics coupled with new types of very weakly coordinating counteranions can provide the basis for a more environmentally friendly, lower energy alternative. Because any copolymerization of two monomers, here primarily isobutene and isoprene, leads to two different propagating species, each of which is characterized by

  17. Survival of Organic Materials in Ancient Cryovolcanically-Produced Halite Crystals

    Science.gov (United States)

    Zolensky, M.; Fries, M.; Chan, Q. H.-S.; Kebukawa, Y.; Bodnar, R.; Burton, A.; Callahan, M.; Steele, A.; Sandford, S.

    2015-01-01

    also far from equilibrium. Cryovolcanoes on Ceres are a potential source of our halite, however the processes that form halite should also be operating within Europa. Dissolution of Monahans halite grains has revealed a remarkable variety of organics, which dominate the population of solid inclusions. Thermal alteration of this macromolecular carbon (measured by Raman spectroscopy) shows remarkable diversity. We have identified highly-condensed aromatics, diamond, carbonates and chloromethane. Light organic compounds like methane tend to be water soluble and require cold formation temperatures at high hydrogen fugacity - i.e. require water ice. Another indication that these halites have not been heated is that light organics readily volatilize or aromaticize into PAHs. We are currently analyzing the organics by Raman and C-XANES, and measuring the content and exploring the potential chirality of amino acids in the halite. Implications for Europa Plumes: Organic materials and structures erupted by a Europa cryovolcano should be similarly preserved within halite, and other salts, which will be a convenient form for capture and analysis, since halite will serve to encapsulate and protect the organics from spacecraft contamination. Also, being transparent at many wavelengths halite will permit analysis by spacecraft-mounted spectroscopic techniques. In addition, halite is readily dissolved, permitting further analysis of entrained organics.

  18. Design and Performance of an Enhanced Bioremediation Pilot Test in a Tidal Wetland Seep, West Branch Canal Creek, Aberdeen Proving Ground, Maryland

    Science.gov (United States)

    Majcher, Emily H.; Lorah, Michelle M.; Phelan, Daniel J.; McGinty, Angela L.

    2009-01-01

    unconsolidated sediments between 1.5 and 6 years following installation of the reactive mat. To ensure hydraulic compatibility in the mat design, mat materials that had a hydraulic conductivity greater than the surrounding wetland sediments were selected, and the mixture was optimized to consist of 1.5 parts compost, 1.5 parts peat and 1 part sand as a safeguard against fluidization. Sediment and matrix properties also indicated that a nonwoven geotextile with a cross-plane flow greater than that of the native sediments was suitable as the base of the reactive mat. Another nonwoven geotextile was selected for installation between the iron mix and organic zones of the mat to create more laminar flow conditions within the mat. Total metals and sequential extraction procedure analyses of mat materials, which were conducted to evaluate water-quality compatibility of the mat materials, showed that concentrations of metals in the compost ranged from one-half to one order of magnitude below consensus-based probable effect concentrations in sediment. A 22-inch-thick reactive mat, containing 0.5 percent WBC-2 by volume, was constructed at seep area 3-4W and monitored from October 2004 through October 2005 for the pilot test. No local, immediate failure of the mat or of wetland sediments was observed during mat installation, indicating that design estimates of bearing capacity and geotextile textile selection ensured the integrity of the mat and wetland sediments during and following installation. Measurements of surface elevation of the mat showed an average settlement of the mat surface of approximately 0.25 feet after 10 months, which was near the predicted settlement for unconsolidated sediment. Monitoring showed rapid establishment and sustainment throughout the year of methanogenic conditions conducive to anaerobic biodegradation and efficient dechlorination activity by WBC-2. The median mass removal of chloromethanes and total chloroethenes and ethane during the

  19. Progress Report on the ISCR Pilot Test Conducted at the Former CCC/USDA Grain Storage Facility in Montgomery City, Missouri, as of April 2013

    Energy Technology Data Exchange (ETDEWEB)

    LaFreniere, Lorraine M. [Argonne National Lab. (ANL), Argonne, IL (United States). Environmental Science Division. Applied Geoscience and Environmental Restoration Program

    2013-06-01

    The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) is conducting an environmental investigation at the former CCC/USDA grain storage facility on the county fairgrounds in Montgomery City, Missouri, to evaluate contamination associated with the former use of grain fumigants containing carbon tetrachloride at the site. The CCC/USDA studies have identified carbon tetrachloride in the soils (primarily unconsolidated glacial tills) at concentrations that exceed the U.S. Environmental Protection Agency (EPA) regional screening level (RSL) values for this compound in residential soils (610 μg/kg) but are below the corresponding RSL for industrial soils (3,000 μg/kg). Concentrations of carbon tetrachloride greater than the EPA maximum contaminant level (MCL; 5.0 μg/L) for this contaminant in drinking water were also identified in the shallow groundwater (Argonne 2012). On the basis of these findings, remedial actions are considered necessary to mitigate the present and potential future impacts of the contamination. In cooperation with the Missouri Department of Natural Resources (MDNR), the CCC/USDA has initiated a field-scale pilot test to evaluate an in situ technology for treatment of the carbon tetrachloride contamination. In this approach, a chemical amendment consisting primarily of slow-release organic matter and zero-valent iron is employed to induce oxygen-depleted, chemically reducing conditions in the subsurface. These conditions foster the in situ chemical reduction (ISCR) of carbon tetrachloride and its degradation products (chloroform, methylene chloride, and chloromethane) via both inorganic and biologically mediated processes. The chemical amendment being used, EHC™, was developed by the Adventus Group, Freeport, Illinois, and is now manufactured and distributed by FMC Environmental Solutions, Philadelphia, Pennsylvania. With the approval of the MDNR (2012), the ISCR technology is being tested in two target areas

  20. Simultaneous determination of eight additives in polymer food packaging materials by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry%超高效液相色谱-串联质谱法同时测定聚合物食品包装材料中8种添加剂

    Institute of Scientific and Technical Information of China (English)

    张旭龙; 刘银; 巩治国; 王鹏举; 王吉德; 封顺

    2014-01-01

    建立了同时测定聚合物食品包装材料中8种常用添加剂 Irgafos 168、Irganox 1010、Irganox 1076、丁基羟基茴香醚(BHA)、没食子酸丙酯(PG)、没食子酸十二酯( DG)、叔丁基对苯二酚( TBHQ)和苯三唑甲酚( UV-326)的超高效液相色谱-串联质谱方法。试样以二氯甲烷为溶剂进行超声提取;采用 Waters BEH-C18柱(50 mm ×2.1 mm,1.7μm)分离,以0.05%甲酸水溶液和甲醇为流动相进行梯度洗脱;采用电喷雾离子源正、负离子切换模式和多反应监测模式进行检测。8种添加剂在相应的质量浓度范围内定量离子的峰面积与质量浓度均呈良好线性关系(相关系数 R2均大于0.993),回收率为63.9%~127.0%,相对标准偏差(RSD,n =6)≤15.8%,检出限( S / N =3)为0.13~5.50μg / L,定量限(S / N =10)为0.45~17.50μg / L。该方法简便快捷、灵敏度高,适合食品包装材料中常用添加剂的分析测定。%An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS / MS)method was proposed for the simultaneous determination of eight additives ( Irgafos 168(tri(2. 4-di-tert-butylphenyl)phosphite),Irganox 1076(octadecyl-β-(4-hydroxy-3, 5-di-tert-butyl- phenyl)propionate),Irganox 1010(pentaerythritol tetrakys 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate),BHA( butyl hydroxy anisole),TBHQ( tertiary butylhydroqui-none),PG( propyl gallate),DG( dodecyl gallate),UV-326( 2-( 2′-hydroxyl-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole ) in food packaging materials. After extracted by chlo-romethane through ultrasonic extraction,the samples were analyzed by UPLC-MS / MS. The chromatographic conditions were optimized,and the best separation was obtained on a Waters BEH-C18 column(50 mm×2. 1 mm,1. 7 μm)with gradient elution of 0. 05% acetic acid solu-tion and methanol. The analysis was performed by UPLC-MS / MS with electrospray ionization (ESI)source in

  1. Reactive hydro- end chlorocarbons in the troposphere and lower stratosphere : sources, distributions, and chemical impact

    Science.gov (United States)

    Scheeren, H. A.

    2003-09-01

    The work presented in this thesis focuses on measurements of chemical reactive C2 C7 non-methane hydrocarbons (NMHC) and C1 C2 chlorocarbons with atmospheric lifetimes of a few hours up to about a year. The group of reactive chlorocarbons includes the most abundant atmospheric species with large natural sources, which are chloromethane (CH3Cl), dichloromethane (CH2Cl2), and trichloromethane (CHCl3), and tetrachloroethylene (C2Cl4) with mainly anthropogenic sources. The NMHC and chlorocarbons are present at relatively low quantities in our atmosphere (10-12 10-9 mol mol-1 of air). Nevertheless, they play a key role in atmospheric photochemistry. For example, the oxidation of NMHC plays a dominant role in the formation of ozone in the troposphere, while the photolysis of chlorocarbons contributes to enhanced ozone depletion in the stratosphere. In spite of their important role, however, their global source and sinks budgets are still poorly understood. Hence, this study aims at improving our understanding of the sources, distribution, and chemical role of reactive NMHC and chlorocarbons in the troposphere and lower stratosphere. To meet this aim, a comprehensive data set of selected C2 C7 NMHC and chlorocarbons has been analyzed, derived from six aircraft measurement campaigns with two different jet aircrafts (the Dutch TUD/NLR Cessna Citation PH-LAB, and the German DLR Falcon) conducted between 1995 and 2001 (STREAM 1995 and 1997 and 1998, LBA-CLAIRE 1998, INDOEX 1999, MINOS 2001). The NMHC and chlorocarbons have been detected by gas-chromatography (GC-FID/ECD) in pre-concentrated whole air samples collected in stainless steel canister on-board the measurement aircrafts. The measurement locations include tropical (Maldives/Indian Ocean and Surinam), midlatitude (Western Europe and Canada) and polar regions (Lapland/northern Sweden) between the equator to about 70ºN, covering different seasons and pollution levels in the troposphere and lower stratosphere. Of