Nitrogen dioxide, mass spectrometry

The reaction was second order in acid and first order in substrate, so both rearrangements and the disproportionation reaction proceed via the doubly-protonated hydrazobenzene intermediate formed in a rapid pre-equilibrium step. The nitrogen and carbon-13 kinetic isotope effects were measured to learn whether the slow step of each reaction was concerted or stepwise. The nitrogen and carbon-13 kinetic isotope effects were measured using whole-molecule isotope ratio mass spectrometry of the trifluoroacetyl derivatives of the amine products and by isotope ratio mass spectrometry on the nitrogen and carbon dioxide gases produced from the products. The carbon-12/carbon-14 isotope... 

This system was studied by Schwartz. Toluene at 10 ppm, nitric oxide at 1 ppm, and nitrogen dioxide at 1.2 ppm were irradiated with ultraviolet lamps in a 17-m batch reactor for 270 min. Collected aerosols were successively extracted with methylene chloride and then methanol. The methylene chloride extract was fractionated into water-soluble and water-insoluble material, and the latter fraction was further divided into acidic, neutral, and basic fractions. The acidic and neutral fractions were analyzed by gas chromatography and chemical-ionization mass spectrometry the compounds identified are shown in Figure 3-7. The two analyzed fractions represented only about 5.5% of the total aerosol mass. It is noteworthy that classical nitration of an aromatic ring appears to... 

Accordingly, a 0-1 molar solution of phthalic anhydride in benzene (100 ml.) was pyrolyzed at 690° under nitrogen at a steady rate of 30 ml/hr (Fields and Meyerson, 1965). The pyrolysis tube was Vycor, filled with Vycor beads contact time was 11 5 sec, which gave a 58% conversion of the phthalic anhydride. Acetylene was steadily evolved, along with carbon dioxide and carbon monoxide in a 1 1 ratio these were identified in the gas stream by mass-spectral analysis of samples taken at regular intervals. The benzene was distilled off and the products boiling over 180° (2 g) were analyzed by mass spectrometry on a Consolidated Model... 

Analysis of the exit gases by mass spectrometry gave these results (nitrogen-free basis carbon monoxide confirmed in a similar run under helium) carbon dioxide, 45-6 carbon monoxide, 45-4 hydrogen cyanide, 1-8 acetylene, 0-4 hydrogen, 6-8 all values in mole per cent. 

The NO reactions (decomposition and reaction with propene or propane) were carried out in a recirculatory batch reactor with mass spectrometric analysis (details see in [2]). The catalyst sample (0.5 g) was activated in dioxygen at 723 K for 4 hours before each measurement. The gas-phase concentrations of reactants and products were measured by mass spectrometry. Mass munbers 41 of propene, 43 of propane, 46 of nitrogen dioxide and 30 of NO were used for analysis. 

Acid solutions of dimeric, oligomeric and polymerized procyanidins are unstable. Even under nitrogen with sulfur dioxide in the absence of light, the color yellows, then browns and, after a short time, a precipitate is observed. At pH 3.2, the reaction takes about ten months at 5°C, a few months at 20°C and one to two months at 30°C. In the presence of oxygen from the air, and especially at high temperatures, conversion of the solution is more intense and the precipitates look different. It is impossible to dissolve them in any solvents other than formic acid. They can only be studied after acetylation. Results obtained by molecular screening (TSK), NMR and mass spectrometry show that these complex polymers have molecular weights above 3000. 

The isotopic peaks of silver Ag" and ° Ag" suggest a high sensitivity for this metal. Metal impurities of Na, Cu and Cu are detected besides peaks due to organic ions. Furthermore, corresponding to m/z 19 (OHj ) and m/z 30 (NO" ") which come from nitrogen, oxygen, carbon dioxide, and water present in the carrier gas argon are found. The method of plasma ion mass spectrometry is very sensitive and only small amounts of sample are used. The detection limit for some metals (Ag, As, Co, Pb) is below 1 ppb. 

CF-IRMS Continuous flow-isotope ratio mass spectrometry. A procedure that uses an instrument that is capable of repeatedly and rapidly measuring the masses of selected gases (e.g., carbon dioxide, hydrogen, nitrogen) delivered in a continuous gas stream from another instrument, such as an elemental analyzer or a gas chromatograph, to determine their isotopic compositions. 

Baratto C, Fagha G, SbervegUeri G, Boarino L, Rossi AM, Amato G (2001) Front-side micromachined porous silicon nitrogen dioxide gas sensor. Thin Sohd Films 391 261-264 Barber M, Sharpe P, Vickerman JC (1974) An investigation of the SO /Ag surface reaction using secondary ion mass spectrometry. Chem Phys Lett 27 436-438... 

Next, low-temperature (<150°C), low-pressure torr) oxygen plasmas oxidized organic components of the sample to CO2. Decomposition of inorganic carbon present (dolomitic limestone rock and calcite/calcium oxalate accretions) was prevented by running the plasmas at low-temperature. Carbon dioxide from the sample was flame-sealed into a glass tube cooled to liquid nitrogen temperature (-194°C), after water had been frozen out with a dry-ice/ethanol slurry (-58°C), and finally sent for radiocarbon analysis at the Center for Accelerator Mass Spectrometry at the Lawrence Livermore National Laboratory (LLNL-CAMS). It was necessary to utilize an AMS measurement due to the small sample size. 

Davis, D.D., Prusazcyk, J., Dwyer, M., Kim, P. Stop-flow time-of-flight mass spectrometry kinetics study. Reaction of ozone with nitrogen dioxide and sulfur dioxide. J. Phys. Chem. 78, 1775-1779 (1974)... 

In most cases, the thermal decompositions lead to a coevolution of several materials, particularly when the backbone of the polymer is broken apart. Because of the mbcture of products generated, identification of the constituents could only be made through the use of spectral subtraction or when small molecules with simple infrared spectra, such as carbon monoxide, carbon dioxide, and hydrogen chloride were generated. In the study on polyacrylamide (2), the effluent was trapped in a gas collection tube immersed in liquid nitrogen and then separated and analyzed by GC/FT-IR and gas chromatography/mass spectrometry. 

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