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The anthropogenic CO2 (Cant) estimates from cruises spanning more than two decades (1981–2006) in the Irminger Sea area of the North Atlantic Subpolar Gyre reveal a large variability in the Cant storage rates. During the early 1990's, the Cant storage rates (2.3±0.6 mol C m−2 yr−1) doubled the average rate for 1981–2006 (1.1±0.1 mol C m−2 yr−1), whilst a remarkable drop to almost half that average followed from 1997 onwards. The Cant storage evolution runs parallel to chlorofluorocarbon-12 inventories and is in good agreement with Cant uptake rates of increase calculated from sea surface pCO2 measurements. The contribution of the Labrador Seawater to the total inventory of Cant in the Irminger basin dropped from 66% in the early 1990s to 49% in the early 2000s. The North Atlantic Oscillation shift from a positive to a negative phase in 1996 led to a reduction of air-sea heat loss in the Labrador Sea. The consequent convection weakening accompanied by an increase in stratification has lowered the efficiency of the northern North Atlantic CO2 sink.

The proton transfer reaction mass spectrometry (PTR-MS) is used to follow the toluene concentration at the exit of a dielectric barrier discharge, for an inlet gas mixture of dry air with organic molecules at a concentration in the range 10–100 ppm, at atmospheric pressure and room temperature. The precursor ion is H3O+, and toluene is detected at mass 93 u, corresponding to the (C6H5CH3)–H+ ion. The PTR-MS is used together with optical absorption spectroscopies to follow ozone and carbon dioxide molecules. Two different discharge regimes are studied: without or with significant self-warming effects. The PTR-MS diagnostic appears as a very useful tool for precise monitoring of the concentration of this organic molecule, and to get real-time information about the energy efficiency for the removal of the pollutant during the discharge operation, as function of the discharge regime. [ABSTRACT FROM AUTHOR]

n -Hexane (C 6 H 14 ) removal and conversion are investigated in a filamentary plasma generated by a pulsed high-voltage Dielectric Barrier Discharge (DBD) at atmospheric pressure and room temperature in a dry N 2 /O 2 (20%) mixture with C 6 H 14 . The degradation of n -hexane and the by-product formation are analyzed in real-time using a high-resolution Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer coupled with Chemical Ionization (CI). As alkanes are reacting slowly with H 3 O + ions, two precursor ions were used: O 2 + to follow the n -hexane mixing ratios and H 3 O + to follow the mixing ratios of organic by-products. As the CI-FTICR technique can work at high mixing ratios, studies were made between 5 and 200 ppm of n -hexane. Absorption spectroscopy is also used to follow ozone and carbon dioxide molecules. We show that the DBD efficiency increases for lower n -hexane mixing ratios and a large number of by-products are identified, with the major compounds being: formaldehyde, acetaldehyde, propanal, carbon dioxide, and carbon monoxide along with nitrate compounds. Based on the nature of the by-products characterized, a mechanism accounting for their formation is proposed.

The noble gas argon has demonstrated biological activity that may prove useful as a medical intervention. Pharmacokinetics, the disposition of the drug molecule in the body through time, is fundamental necessary knowledge to drug discovery, development and even post-marketing. The fundamental measurement in pharmacokinetic studies is blood concentration of the molecule (and its metabolites) of interest. While a physiologically based model of argon pharmacokinetics has appeared in the literature, no experimental data have been published. Thus, argon pharmaceutical development requires measurement of argon solubility in blood. This paper reports on the development of a technique based on mass spectrometry for measuring argon solubility in liquids, including blood, to be further employed in pharmacokinetics testing of argon. Based on a prototype, results are reported from sensitivity experiments using ambient air, water and rabbit blood. The key takeaway is that the system was sensitive to argon during all of the testing. We believe the technique and prototype of the quadrupole mass spectrometer gas analyzer will be capable of inferring argon pharmacokinetics through the analysis of blood samples., Competing Interests: None

The so-called dibenzyltoluene (H0-DBT) heat transfer oil contains numerous isomers of dibenzyltoluene as well as (benzyl)benzyltoluene (methyl group on the central vs. the side aromatic ring). As it is used as a liquid organic hydrogen carrier (LOHC), a detailed analysis of its composition is crucial in assessing the kinetic rate of hydrogenation for each constituent and studying the mechanism of H0-DBT hydrogenation. To identify all of the compounds in the oil, an in-depth analysis of the GC-MS spectra was performed. To confirm peak attribution, we synthesized some DBTs and characterized the pure compounds using NMR and Raman spectroscopies. Moreover, a fast-GC analysis was developed to rapidly determine the degree of hydrogenation of the mixture.

Understanding non-thermal plasma reactivity is a complicated task as many reactions take place due to a large energy spectrum. In this work, we used a well-defined photo-triggered non-filamentous discharge to study acetone decomposition in N 2 /O 2 gas mixtures. The plasma reactor is associated to a compact chemical ionization FTICR mass spectrometer (BTrap) in order to identify and quantify in real-time acetone and by-products in the plasma. Presence of oxygen (1 to 5%) decreased notably acetone degradation. A tremendous change is observed in the by-products distribution concomitantly to a global decrease of their total concentration. While main products observed in oxygen-free gas mix are nitrile compounds, in oxygenated media they are replaced by formaldehyde, methanol and ketene. Methanol is maximum for 1% of O 2 whereas formaldehyde and ketene concentration reach their maximum value at the highest oxygen concentration tested (5%). A number of nitrate, nitrite and isocyanate organic compounds (C1 and C2) are observed as well with HNO 2 , HNO 3 and HNCO.

Methods for reduction of volatile organic compounds (VOCs) content in air depend on the application considered. For low concentration and low flux, nonthermal plasma methods are often considered as efficient. However, the complex chemistry involved is still not well understood because there is a lack of data sets of byproducts formation. To overcome this issue, rapid analytical methods are needed. We present the coupling of a rapid chemical ionization mass spectrometer (CIMS) for the real-time analysis of the VOCs formed during a degradation experiment. The high-resolution instrument used allows for chemical ionization and direct quantification of nontargeted compounds. This method is successfully applied to degradation experiments of acetone in a phototriggered nitrogen plasma discharge. Two regimes were highlighted: efficient conversion at low concentrations (<100 ppm) and moderate efficiency conversion at higher concentrations (>100 ppm). Those two regimes were clearly delimited as the sum of two exponential curves occurring at respectively low and high concentrations. Many byproducts were detected; in particular, HCN presented a significantly high yield. Nitrile compounds (acetonitrile, propionitrile, ...) are formed as well. To a lower extent, ketene, acetaldehyde, and formaldehyde are observed. The association of the high-resolution mass spectrometer to the plasma reactor will allow further insights into the plasma chemistry and comparison to modelization.

Membrane Inlet Mass Spectrometry (MIMS) was used to analyze monochloramine solutions (NH₂Cl) and ammonia solutions in a compact FTICR. Chemical ionization enables identification and quantification of the products present in the permeate. The responses of protonated monochloramine and ammonium increase linearly with the solution concentration. The enrichments were respectively 1.2 and 5.5. Pervaporation is dependent on pH and only the basic form of ammonia NH₃ pervaporates through the membrane. Unexpectedly, the small ammonia molecule permeated very slowly. It could be due to interactions with water molecules inside the membrane that create clusters. Moreover, NH₂Cl solutions, in addition to the NH₃Cl⁺ signal, presented a strong NH₄⁺ signal at m / z 18.034. Ammonia presence in the low-pressure zone before ionization is probable as NH₄⁺ was detected with all the precursors used, particularly CF₃⁺ and trimethylbenzene that presents a proton affinity higher than monochloramine. Ammonia may be formed inside the membrane due to the fact that NH₂Cl is unstable and may react with the water present in the membrane. Those results highlight the need for caution when dealing with chloramines in MIMS and more generally with unstable molecules., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

In this Article, a compact Fourier transform ion cyclotron resonance (FTICR) mass spectrometer based on a permanent magnet is presented. This instrument has been developed for real-time analysis of gas emissions. The instrument is well-suited to industrial applications or analysis of toxic and complex samples where the concentrations can vary rapidly on a wide range. The novelty of this instrument is the ability to use either electron ionization (EI) or chemical ionization (CI) individually or both of them alternatively. Also in CI mode, different precursor ions can be used alternatively. Volatile organic compounds (VOCs) from the ppb level to very high concentrations (% level) can be detected by CI or EI. The magnet is composed of three Halbach arrays, and the nominal field achieved is 1.5 T. The ICR cell is a 3 cm side length cubic cell. The mass range is 12-200 u with a broad band detection. The mass accuracy of 0.005 u and the resolving power allow the separation of isobaric ions such as C 3 H 8 + and CO 2 + . Gas introduction via controlled gas pulses, electron ionization, ion-molecule reactions, ion selection, and detection are all performed in the ICR cell. The potential of the instrument will be illustrated by an analysis of a gas mixture containing trace components at ppm level (VOCs) and components in the 0.5-100% range (N 2 , alkanes, and CO 2 ).

In this paper, we present a compact Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) designed for real time analysis of volatile organic compounds (VOCs) in air or in water. The spectrometer is based on a structured permanent magnet made with NdFeB segments. Chemical ionization is implemented inside the ICR cell. The most widely used reaction is the proton transfer reaction using H₃O⁺ precursor ions, but other ionic precursors can be used to extend the range of species that can be detected. Complex mixtures are studied by switching automatically from one precursor to another. The accuracy obtained on the mass to charge ratio (&Delta; m / z 5 &times; 10 &minus;3 ), allows a precise identification of the VOCs present and the limit of detection is 200 ppb without accumulation. The time resolution is a few seconds, mainly limited by the time necessary to come back to background pressure after the gas pulses. The real time measurement will be illustrated by the monitoring of VOCs produced during the thermal degradation of a polymer and by an example where three different precursor ions are used alternatively to monitor a gas sample.

The reactivity of a series of commonly used halogenated compounds (trihalomethanes, chlorofluorocarbon, hydrochlorofluorocarbon, fluorocarbons, and hydrofluoroolefin) with hydroxide and oxygen anion is studied in a compact Fourier transform ion cyclotron resonance. O - is formed by dissociative electron attachment to N 2 O and HO - by a further ion-molecule reaction with ammonia. Kinetic experiments are performed by increasing duration of introduction of the studied molecule at a constant pressure. Hydroxide anion reactions mainly proceed by proton transfer for all the acidic compounds. However, nucleophilic substitution is observed for chlorinated and brominated compounds. For fluorinated compounds, a specific elimination of a neutral fluorinated alkene is observed in our results in parallel with the proton transfer reaction. Oxygen anion reacts rapidly and extensively with all compounds. Main reaction channels result from nucleophilic substitution, proton transfer, and formal H 2 + transfer. We highlight the importance of transfer processes (atom or ion) in the intermediate ion-neutral complex, explaining part of the observed reactivity and formed ions. In this paper, we present the first reactivity study of anions with HFO 1234yf. Finally, the potential of O - and HO - as chemical ionization reagents for trace analysis is discussed., (Copyright © 2017 John Wiley & Sons, Ltd.)