Sulphur cation chemistry in a fuel-rich, CH4–O2 flame with OCS additive

1986 ◽  
Vol 64 (9) ◽  
pp. 1733-1742 ◽  
Author(s):  
Nicholas S. Karellas ◽  
John M. Goodings
Keyword(s):  
Reaction Zone ◽  
Atmospheric Pressure ◽  
Mass Spectra ◽  
Mass Range ◽  
Major Product ◽  
Premixed Flame ◽  
Ion Concentration ◽  
Concentration Profiles ◽  
Ion Chemistry ◽  
Ion Molecule Reactions

A fuel-rich, methane–oxygen, premixed flame at atmospheric pressure was doped with 0.2 mol% of OCS. More than 40 different sulphurous cations were observed in the mass range < 100 u by sampling the flame into a flame-ion mass spectrometer. Ion concentration profiles along the flame axis are presented, together with mass spectra at fixed points in the flame. In the reaction zone, primary sulphur ions CHxS+ (x = 1, 3, 5) undergo extensive ion–molecule reactions (association and condensation) with CH4/CH3, C2H2, and OCS to form a considerable variety of secondary sulphurous cations. Just downstream of the reaction zone, the ion chemistry is somewhat different; it appears to be dominated by reactions of primary sulphur ions including HxS+ (x = 0–3) with C2H2 present as an intermediate. A few ions (HxS+, OS+, S2+) persist throughout the burnt gas region in equilibrium with the natural flame ions CHO+ and H3O+. These sulphurous cation signals show the evolution of the sulphur chemistry, both ionic and neutral, through the flame reaction zone into the burnt gas downstream where H2S, not SO2, is the major product in fuel-rich combustion.

Comparative sulphur cation chemistry in a hydrocarbon flame with H2S, OCS, and SO2 additives

1986 ◽  
Vol 64 (12) ◽  
pp. 2412-2417 ◽  
Author(s):  
Nicholas S. Karellas ◽  
John M. Goodings
Keyword(s):  
Reaction Zone ◽  
Atmospheric Pressure ◽  
Mass Spectra ◽  
Chemical Ionization ◽  
Negative Ions ◽  
Mass Range ◽  
Total Ionization ◽  
Ion Recombination ◽  
Diffusion Mass ◽  
Oxygen Flame

A fuel-rich, conical, premixed, methane–oxygen flame at atmospheric pressure was doped separately with 0.2 mol% of H2S, OCS, and SO2 to probe the chemistry of sulphur at its source during combustion. These three additives represent a broad range of fuel-sulphur contaminants since they occur early, intermediate, and late in the sulphur oxidation sequence. A wide variety of sulphurous cations, formed by chemical ionization reactions, is observed for each additive by sampling the flame into a mass spectrometer. The total ionization profile measured along the flame axis is enhanced in the reaction zone when a sulphur additive is present; the mechanism involves the formation of sulphurous negative ions which reduces the rates of cation loss by electron–ion recombination and ambipolar diffusion. Mass spectra measured in the mass range 10–110 u at fixed points on the flame axis are very similar for all three additives, and are not helpful in the identification of the additive. However, the general presence of sulphur is evident from large signals measured near the reaction zone at five principal mass numbers; namely, 45 u (CHS+), 47 u (CH3S+), 58 u (C2H2S+), 59 u (C2H3S+), and 69 u (C3HS+) related to CS, thioformaldehyde, thioketene, and C3S.

Sulphurous negative ions in a fuel-rich, CH4–O2 flame with OCS additive

1983 ◽  
Vol 61 (8) ◽  
pp. 1703-1711 ◽  
Author(s):  
John M. Goodings ◽  
Kamal Elguindi ◽  
Diethard K. Bohme
Keyword(s):  
Reaction Zone ◽  
Atmospheric Pressure ◽  
Negative Ions ◽  
Ion Concentration ◽  
Quadrupole Mass ◽  
Ion Chemistry ◽  
Naturally Occurring ◽  
Pressure Profiles ◽  
Ion Profiles ◽  
Carbonyl Sulphide

Sulphurous negative ions S • SH • SO • SO2/S2• SO3• HSO3• SO4• and HSO4 were observed when 0.2% of carbonyl sulphide (OCS) was added to a conical, laminar, premixed. fuel-rich (equivalence ratio [Formula: see text]) CH4–O2 flame burning at atmospheric pressure. Profiles were obtained of ion concentration vs. distance along the flame axis by sampling the flame through a pinhole into a quadrupole mass spectrometer. Some of the ion signals observed in the flame reaction zone are very large, particularly that for HSO4. None of the sulphurous ions detected contain carbon. Of those listed above, only S−,•SH, • SO • and SO2 persist downstream through the burnt gas. The sulphurous ions are formed by chemical ionization processes of neutral sulphurous intermediates reacting with the naturally-occurring ions present in any hydrocarbon flame. The ion chemistry is discussed, as is the underlying neutral chemistry of sulphur relevant to the flame environment. The ion profiles show the rapidity with which OCS is oxidized through SH and SO to SO2 even within the reaction zone of this fuel-rich flame. No evidence was obtained for the presence of sulphuric or sulphurous acids, and the presence of S2: was not confirmed.

Ion chemistry of second-row transition metals in hydrocarbon flames: cations and anions of Y, Zr, Nb, and Mo

1995 ◽  
Vol 73 (12) ◽  
pp. 2263-2271 ◽  
Author(s):  
Christine C.Y. Chow ◽  
John M. Goodings
Keyword(s):  
Transition Metals ◽  
Gas Phase ◽  
Atmospheric Pressure ◽  
Chemical Ionization ◽  
Negative Ions ◽  
Ion Concentration ◽  
Oxidation States ◽  
Metallic Ions ◽  
Ion Chemistry ◽  
Hydrocarbon Flames

A pair of laminar, premixed, CH4–O2 flames above 2000 K at atmospheric pressure, one fuel-rich (FR) and the other fuel-lean (FL), were doped with ~10−6 mol fraction of the second-row transition metals Y, Zr, Nb, and Mo. Since these hydrocarbon flames contain natural ionization, metallic ions were produced in the flames by the chemical ionization (CI) of metallic neutral species, primarily by H3O+ and OH− as CI sources. Both positive and negative ions of the metals were observed as profiles of ion concentration versus distance along the flame axis by sampling the flames through a nozzle into a mass spectrometer. For yttrium, the observed ions include the YO+•nH2O (n = 0–3) series, and Y(OH)4−. With zirconium, they include the ZrO(OH)+•nH2O (n = 0–2) series, and ZrO(OH)3−. Those observed with niobium were the cations Nb(OH)3+ and Nb(OH)4+, and the single anion NbO2(OH)2−. For molybdenum, they include the cations MoO(OH)2+ and MoO(OH)3+, and the anions MoO3− and MoO3(OH)−. Not every ion was observed in each flame; the FL flame tended to favour the ions in higher oxidation states. Also, flame ions in higher oxidation states were emphasized for these second-row transition metals compared with their first-row counterparts. Some ions written as members of hydrate series may have structures different from those of simple hydrates; e.g., YO+•H2O = Y(OH)2+ and ZrO(OH)+•H2O = Zr(OH)3+, etc. The ion chemistry for the production of these ions by CI in flames is discussed in detail. Keywords: transition metals, ions, flame, gas phase, negative ions.

Mass Spectra and Ion Chemistry of Methylphosphine, Dimethylphosphine and Dimethyldeuterophosphine, Investigated by Ion Cyclotron Resonance Spectrometry

1975 ◽  
Vol 30 (3) ◽  
pp. 329-339 ◽  
Author(s):  
Karl-Peter Wanczek
Keyword(s):  
Rate Constants ◽  
Cyclotron Resonance ◽  
Mass Spectra ◽  
Ion Cyclotron Resonance ◽  
Exchange Reactions ◽  
Ion Chemistry ◽  
Ion Molecule Reactions ◽  
Ion Cyclotron ◽  
Product Ions ◽  
Ion Cyclotron Resonance Spectrometry

The mass spectra and the ion molecule reactions of methylphosphine, dimethylphosphine and dimethyldeuterophosphine have been studied by ion cyclotron resonance spectrometry. About 50 ion molecule reaction are observed for each compound. The product ions can be classified as ions with two phosphorus atoms: P2R5+, P2R3+, P2R2+ and P2R+ (R = CH3 or H), as phosphonium and phosphinium ions and ions resulting from collision dissociations and charge exchange reactions. Tertiary ions with three phosphorus atoms like CH3P3H2+ (from CH3PH2) and (CH3)4P3H2 (from (CH3)2PH) have also been detected. The mechanisms of the ion molecule reactions, rearrangements, P -H- and C-H-reactivities and product ion structures are discussed, using in the case of dimethylphosphine the results obtained with the deuterated compound. Rate constants of formation of the more abundant product ions from the molecular ion and the CH3P+ ion, both odd electron particles, have been determined. The reactions with dimethylphosphine have much smaller rate constants than the reactions with methylphosphine.

Flame-ion probe of the reaction zone in a CH4–O2–Ar flame with added HCN, NH3 and NO

1981 ◽  
Vol 59 (12) ◽  
pp. 1810-1818 ◽  
Author(s):  
John M. Goodings ◽  
Gary B. De Brou ◽  
Diethard K. Bohme
Keyword(s):  
Reaction Zone ◽  
Atmospheric Pressure ◽  
Protonated Form ◽  
Good Evidence ◽  
Ion Concentration ◽  
Bimolecular Reactions ◽  
Hydrocarbon Flames ◽  
Ion Probe ◽  
Increased Sensitivity ◽  
N Compounds

The addition of 0.3% of the fuel-nitrogen (fuel-N) compounds HCN, NH3, or NO to a premixed, fuel-rich, CH4–O2–Ar flame burning at atmospheric pressure demonstrated the rapid interconversion of nitrogenous intermediates in the reaction zone. The nitrogenous species (HCN/CN, HNCO/NCO, NH3, NH2, NH, NO, NO2) were observed as ions (CN−, H2CN+, NCO−, H2NCO+, NH4+, NH3+, NH2+, NO+, NO2−, and hydrate ions) formed in chemical ionization processes discussed previously (1). The ions were sampled directly into a flame-ion mass spectrometer which had sufficient spatial resolution for the measurement of ion concentration profiles through the reaction zone. The study bears on Fenimore's suggestion for the formation of "prompt NO" in fuel-rich hydrocarbon flames. These additive results were compared with previous results involving nitrogenous species present in a similar CH4–O2 flame doped with 10% N2. The increased sensitivity of the additive approach confirmed many of the mass assignments and mechanisms involved in the N2 study. Reasonably good evidence was obtained for the elusive intermediate HNCO (and possibly isomeric HCNO as well) in protonated form, and also formamide, NH2CHO, which had not been detected previously. Similarities in profile peak positions and magnitudes observed for many ions, irrespective of the nature of the fuel-N additive, indicated that the nitrogenous species were linked by a network of fast bimolecular reactions, many of which appeared to be balanced in the reaction zone.

Sulphur anion chemistry in hydrocarbon flames with H2S, OCS, and SO2 additives

1986 ◽  
Vol 64 (4) ◽  
pp. 689-694 ◽  
Author(s):  
John M. Goodings ◽  
Diethard K. Bohme ◽  
Kamal Elguindi ◽  
Arnold Fox
Keyword(s):  
Rate Constants ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Negative Ions ◽  
Ion Concentration ◽  
Concentration Profiles ◽  
Hydrocarbon Flame ◽  
Flowing Afterglow ◽  
Hydrocarbon Flames ◽  
Oxygen Flame

A premixed, fuel-rich, methane–oxygen flame at atmospheric pressure was doped separately with 0.2 mol% of H2S, OCS, and SO2 to probe the behaviour of fuel sulphur during combustion. These three additives represent compounds occurring early, intermediate, and late in the oxidation sequence of fuel sulphur. They are chemically ionized in the reaction zone of a hydrocarbon flame to give large signals of sulphurous negative ions. Those detected include S−, SH−, SO− (uncertain), SO2− (S2−), SO3−, HSO3−, CH3O−•SO2, SO4− (S2O2−, S3−), and HSO4−. Ion concentration profiles of these ions were measured along the conical flame axis by sampling the flame into a mass spectrometer. The shapes of the profiles are insensitive to the nature of the additive, but their relative magnitudes are indicative of the additive's position in the sulphur oxidation sequence. For each additive, the very large HSO4− signal has analytical implications as an indicator for total fuel sulphur. The sulphurous anion chemistry is discussed for each additive in terms of roughly twenty ion (electron)-molecule reactions of six basic types, whose rate constants were known previously, or were measured at room temperature using the York flowing afterglow apparatus.

Hydrocarbon ions in fuel-rich, CH4–C2H2–O2 flames as a probe for the initiation of soot: an experimental approach

1981 ◽  
Vol 59 (12) ◽  
pp. 1760-1770 ◽  
Author(s):  
Scott D. Tanner ◽  
John M. Goodings ◽  
Diethard K. Bohme
Keyword(s):  
Reaction Zone ◽  
Soot Formation ◽  
Unsaturated Hydrocarbon ◽  
Ion Concentration ◽  
Negative Ion ◽  
Ion Chemistry ◽  
Positive Ions ◽  
Total Ionization ◽  
Ion Profiles ◽  
Positive Ion

The natural hydrocarbon ions CnHx± (n ≥ 2, x ≥ 0) present in premixed, fuel-rich, nearly sooting, CH4–C2H2–O2 flames at atmospheric pressure were studied as a probe of the early chemical stages of soot formation. Ion concentration profiles were measured mass-spectrometrically along the flame axis through the reaction zone into the burnt gas downstream. Total ionization profiles were examined for their dependence on both temperature and equivalence ratio, [Formula: see text] Families of individual CnHx− negative ion profiles exhibit concentration peaks in three distinct regions; predominantly oxygenated ions occur upstream, giving way to moderately unsaturated hydrocarbon ions near the end of the reaction zone, leading to highly unsaturated carbonaceous ions further downstream. The concentrations of the downstream ions alternate with the parity of n, the even-n species being larger. Series of CnHx+ positive ion profiles, for a given n, show profile peak positions which move steadily downstream with decreasing x, indicative of progressive dehydrogenation. The positive ion chemistry of these series is essentially independent of n. As [Formula: see text] is increased at constant temperature towards the sooting point, the concentrations of CnHx± ions increase while those of the oxygenated ions decrease; the positive ions show a relative enhancement of species having high values of n.

scholarly journals Data-Independent Acquisition for the Quantification and Identification of Metabolites in Plasma

Metabolites ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 514
Author(s):  
Tom van der Laan ◽  
Isabelle Boom ◽  
Joshua Maliepaard ◽  
Anne-Charlotte Dubbelman ◽  
Amy C. Harms ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Mass Range ◽  
Correct Identification ◽  
Hydrophilic Interaction ◽  
Specific Mass ◽  
Structural Isomers ◽  
Data Independent Acquisition ◽  
Targeted Analysis ◽  
Theoretical Mass ◽  
Accurate Quantification

A popular fragmentation technique for non-targeted analysis is called data-independent acquisition (DIA), because it provides fragmentation data for all analytes in a specific mass range. In this work, we demonstrated the strengths and weaknesses of DIA. Two types of chromatography (fractionation/3 min and hydrophilic interaction liquid chromatography (HILIC)/18 min) and three DIA protocols (variable sequential window acquisition of all theoretical mass spectra (SWATH), fixed SWATH and MSALL) were used to evaluate the performance of DIA. Our results show that fast chromatography and MSALL often results in product ion overlap and complex MS/MS spectra, which reduces the quantitative and qualitative power of these DIA protocols. The combination of SWATH and HILIC allowed for the correct identification of 20 metabolites using the NIST library. After SWATH window customization (i.e., variable SWATH), we were able to quantify ten structural isomers with a mean accuracy of 103% (91–113%). The robustness of the variable SWATH and HILIC method was demonstrated by the accurate quantification of these structural isomers in 10 highly diverse blood samples. Since the combination of variable SWATH and HILIC results in good quantitative and qualitative fragmentation data, it is promising for both targeted and untargeted platforms. This should decrease the number of platforms needed in metabolomics and increase the value of a single analysis.

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