Search results for "Atmospheric Pressure"
showing 10 items of 105 documents
Identification of organic hydroperoxides and hydroperoxy acids in secondary organic aerosol formed during the ozonolysis of different monoterpenes an…
2009
On-line ion trap mass spectrometry (ITMS) enables the real-time characterization of reaction products of secondary organic aerosol (SOA). The analysis was conducted by directly introducing the aerosol particles into the ion source. Positive-ion chemical ionization at atmospheric pressure (APCI(+)) ITMS was used for the characterization of constituents of biogenic SOA produced in reaction-chamber experiments. APCI in the positive-ion mode usually enables the detection of [M+H](+) ions of the individual SOA components. In this paper the identification of organic peroxides from biogenic volatile organic compounds (VOCs) by on-line APCI-ITMS is presented. Organic peroxides containing a hydroper…
Comparison of the activity, selectivity and decay properties of lay and hyultrastable zeolites during the cracking of alkanes
1984
Abstract The cracking of n-heptane on LaY ultrastable zeolite has been studied in a continuous glass flow reactor, at atmospheric pressure, up to 470°C. The initial selectivity to cracking, isomerization and disproportionation, kinetic rate constants, activation energies and decay parameters have been calculated and compared with those obtained using a HY ultrastable zeolite as a catalyst. It has been found that the HY ultrastable zeolite is about 7 times more active for cracking, and about 10 times more active for isomerization and disproportionation than the LaY ultrastable zeolite. The protolytic to β-cracking ratio is higher for the HY ultrastable zeolite. The deactivation takes place b…
Analytical capabilities of high performance liquid chromatography – Atmospheric pressure photoionization – Orbitrap mass spectrometry (HPLC-APPI-Orbi…
2015
A new analytical method was established and validated for the analysis of 27 brominated flame retardants (BFRs), including so called "emerging" and "novel" BFRs (EBFRs and NBFRs) in fish samples. High performance liquid chromatography (HPLC) coupled to Orbitrap mass spectrometry (Orbitrap-MS) employing atmospheric pressure photoionization (APPI) interface operated in negative mode was used for the identification/quantitation of contaminants. HPLC-Orbitrap-MS analysis provided a fast separation of selected analytes within 14 min, thus demonstrating a high throughput processing of samples. The developed methodology was tested by intralaboratory validation in terms of recovery, repeatability, …
Study of separation of water + 2-propanol mixture using different ionic liquids: 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or 1-b…
2018
Abstract The liquid–liquid equilibria data of water (1) + 2-propanol (2) + [bmim][Tf2N] (3) and water (1) + 2-propanol (2) + [bmp][Tf2N] (3) at 283.2, 303.2 and 323.2 K and atmospheric pressure were measured with the objective of understanding the behavior of these two systems and to try to improve the extraction of 2-propanol from water from economical and environmental points of view. The thermodynamic parameters were determined using the non-random two-liquid (NRTL) and universal quasichemical (UNIQUAC) models, and excellent results were achieved in both cases (the maximum root-mean-square deviation was 0.433%). Lastly, the capability of the two ionic liquids to separate 2-propanol from …
Studies of the bromine spectrum and determination of transition probabilities for Br I and Br II lines
1999
In a wall-stabilized cascade arc at atmospheric pressure in mixtures of argon and bromine vapors thermal plasmas were generated. Arc currents between 25 and 60 A were used. Applying a spectrometer of medium dispersion, equipped with an optical multichannel analyzer (CCD detector), the spectra of neutral and singly ionized bromine in the range between 3300 and 10400 A were recorded. Line intensity measurements, corrected for self-absorption, at different operating conditions of the arc, were performed. A complete set of Br I transitions (5 lines) originating from a common upper level (branching fractions) was measured. In the case of the Br II spectrum intensities of 14 lines were determined…
In situ detection of atomic and molecular iodine using resonance and off-resonance fluorescence by lamp excitation: ROFLEX
2018
17 pags, 11 figs, 4 tabs
Summertime columnar content of atmospheric water vapor from ground-based Sun-sky radiometer measurements through a new in situ procedure
2010
[1] A new in situ technique for the retrieval of atmospheric water vapor content (i.e., precipitable water content) from Sun photometric direct solar irradiance measurements, taken at the 940 nm wavelength during clear‐sky conditions, is presented. The procedure is applied to summer data recorded in 2007, 2008, and 2009 with a Sun‐sky radiometer at the San Pietro Capofiume station in the Po valley, Italy. It is a preliminary development of the retrieval procedure providing the columnar water vapor content from measurements performed with PREDE Sun‐sky radiometers. The technique brings improvement and innovation by retrieving the best values of constants (a and b), characterizing atmospheric…
A study on the fragmentation of sulfuric acid and dimethylamine clusters inside an atmospheric pressure interface time-of-flight mass spectrometer
2022
Abstract. Sulfuric acid and dimethylamine vapours in the atmosphere can form molecular clusters, which participate in new particle formation events. In this work, we have produced, measured, and identified clusters of sulfuric acid and dimethylamine using an electrospray ionizer coupled with a planar-differential mobility analyser, connected to an atmospheric pressure interface time-of-flight mass spectrometer (ESI–DMA–APi-TOF MS). This set-up is suitable for evaluating the extent of fragmentation of the charged clusters inside the instrument. We evaluated the fragmentation of 11 negatively charged clusters both experimentally and using a statistical model based on quantum chemical data. Th…
Application of an O-ring pinch device as a constant-pressure inlet (CPI) for airborne sampling
2020
We present a novel and compact design of a constant-pressure inlet (CPI) developed for use in airborne aerosol mass spectrometry. In particular, the inlet system is optimized for aerodynamic lenses commonly used in aerosol mass spectrometers, in which efficient focusing of aerosol particles into a vacuum chamber requires a precisely controlled lens pressure, typically of a few hectopascals. The CPI device can also be used in condensation particle counters (CPCs), cloud condensation nucleus counters (CCNCs), and gas-phase sampling instruments across a wide range of altitudes and inlet pressures. The constant pressure is achieved by changing the inner diameter of a properly scaled O-ring that…
Une méthode rapide et simple pour l'estimation de la position de la courbe de dissociation de l'oxyhémoglobine
1989
The methods currently available for assessing the oxyhaemoglobin dissociation curve parameters are expensive, lengthy, require a large volume of blood, and the results obtained are modified by anaesthetic gases. The equipment required for the method described includes: a microtonometre, microcuvettes, 3 gas bottles containing different oxygen, carbon dioxide and nitrogen mixtures (4.5%, 5.6%, 89.9%; 3.5%, 5.6%, 90.9%; 2.5%, 5.6%, 91.9% respectively), a microxymetre, and a micropHmetre. The samples in the microcuvettes are incubated at 37 degrees C in a gas flow of 45 ml.min-1 from the bottles. SO2 is then read using the microxymetre. P50, i.e. PO2 at 50% saturation, is calculated, as well a…