scholarly journals Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

2016 ◽  
Author(s):  
Caroline C. Womack ◽  
J. Andrew Neuman ◽  
Patrick R. Veres ◽  
Scott J. Eilerman ◽  
Charles A. Brock ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Reactive Nitrogen Species ◽  
Thermal Dissociation ◽  
Ambient Air ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Nitrogen Species ◽  
Operating Characteristics ◽  
Experimental Conditions ◽  
Standard Additions

Abstract. The sum of all reactive nitrogen species (NOy) includes NOx (NO2 + NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser induced fluorescence (LIF) and cavity ringdown spectroscopy (CRDS) to measure total NOy when set at > 600 °C, or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet, as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400 °C, nominally the set point used to selectively convert organic nitrates, can range from 2–6 % and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens, and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas phase N2O5 and particulate ammonium nitrate in the TD inlet at 650 °C, the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3, and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5–10 %) of NH3 to NO at 650 °C in the presence of representative (50 ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

scholarly journals Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

2017 ◽  
Vol 10 (5) ◽  
pp. 1911-1926 ◽  
Author(s):  
Caroline C. Womack ◽  
J. Andrew Neuman ◽  
Patrick R. Veres ◽  
Scott J. Eilerman ◽  
Charles A. Brock ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Reactive Nitrogen Species ◽  
Thermal Dissociation ◽  
Ambient Air ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Nitrogen Species ◽  
Operating Characteristics ◽  
Experimental Conditions ◽  
Standard Additions

Abstract. The sum of all reactive nitrogen species (NOy) includes NOx (NO2 + NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at > 600 °C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400 °C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6 % and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650 °C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5–10 %) of NH3 to NO at 650 °C in the presence of representative (50 ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular characterization of this interference using standard additions of NH3 to TD instruments that convert reactive nitrogen to NO or NO2.

scholarly journals A low power flexible dielectric barrier discharge disinfects surfaces and improves the action of hydrogen peroxide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sophia Gershman ◽  
Maria B. Harreguy ◽  
Shurik Yatom ◽  
Yevgeny Raitses ◽  
Phillip Efthimion ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Dielectric Barrier Discharge ◽  
Atmospheric Pressure ◽  
Reactive Nitrogen Species ◽  
Barrier Discharge ◽  
Ambient Air ◽  
Hydrogen Peroxide Solution ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Dielectric Barrier

AbstractThere is an urgent need for disinfection and sterilization devices accessible to the public that can be fulfilled by innovative strategies for using cold atmospheric pressure plasmas. Here, we demonstrate a successful novel combination of a flexible printed circuit design of a dielectric barrier discharge (flex-DBD) with an environmentally safe chemical reagent for surface decontamination from bacterial contaminants. Flex-DBD operates in ambient air, atmospheric pressure, and room temperature without any additional gas flow at a power density not exceeding 0.5 W/cm2. The flex-DBD activation of a 3% hydrogen peroxide solution results in the reduction in the bacterial load of a surface contaminant of > 6log10 in 90 s, about 3log10 and 2log10 better than hydrogen peroxide alone or the flex-DBD alone, respectively, for the same treatment time. We propose that the synergy between plasma and hydrogen peroxide is based on the combined action of plasma-generated OH· radicals in the hydrogen peroxide solution and the reactive nitrogen species supplied by the plasma effluent. A scavenger method verified a significant increase in OH· concentration due to plasma treatment. Novel in-situ FTIR absorption spectra show the presence of O3, NO2, N2O, and other nitrogen species. Ozone dissolving in the H2O2 solution can effectively generate OH· through a peroxone process. The addition of the reactive nitrogen species increases the disinfection efficiency of the hydroxyl radicals and other oxygen species. Hence, plasma activation of a low concentration hydrogen peroxide solution, using a hand-held flexible DBD device results in a dramatic improvement in disinfection.

scholarly journals Azanone (HNO): generation, stabilization and detection

2021 ◽  
Author(s):  
Cecilia Mariel Gallego ◽  
Agostina Mazzeo ◽  
Paola Vargas ◽  
Sebastián Suárez ◽  
Juan Pellegrino ◽  
...  
Keyword(s):  
Reactive Nitrogen Species ◽  
High Reactivity ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Biologically Relevant

HNO (nitroxyl, azanone), joined the ‘biologically relevant reactive nitrogen species’ family in the 2000s. Azanone is impossible to store due to its high reactivity and inherent low stability. Consequently, its...

Plasmonic Enhancement of Nitric Oxide Generation

Nanoscale ◽  
2021 ◽  
Author(s):  
Rachael Knoblauch ◽  
Chris Geddes
Keyword(s):  
Nitric Oxide ◽  
Reactive Oxygen Species ◽  
Reactive Nitrogen Species ◽  
Reactive Oxygen ◽  
Reactive Nitrogen ◽  
Oxygen Species ◽  
Nitrogen Species ◽  
Plasmonic Enhancement ◽  
Cancer Treatments

While the utility of reactive oxygen species in photodynamic therapies for both cancer treatments and antimicrobial applications has received much attention, the inherent potential of reactive nitrogen species (RNS) including...

scholarly journals A Generator of Peroxynitrite Activatable with Red Light

2021 ◽  
Author(s):  
Cristina Parisi ◽  
Mariacristina Failla ◽  
Aurore Fraix ◽  
Luca Menilli ◽  
Francesca Moret ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Reactive Nitrogen Species ◽  
Red Light ◽  
Reactive Oxygen ◽  
Reactive Nitrogen ◽  
Oxygen Species ◽  
Nitrogen Species ◽  
New Horizons ◽  
Light Stimuli ◽  
Spatiotemporal Control

The generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as “unconventional” therapeutics with precise spatiotemporal control by using light stimuli may open entirely new horizons for innovative...

scholarly journals What Did We Accomplish in Fighting Radical Species in Human Health?

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 466
Author(s):  
Rachid Skouta
Keyword(s):  
Reactive Oxygen Species ◽  
Human Health ◽  
Reactive Nitrogen Species ◽  
Reactive Oxygen ◽  
The Body ◽  
Reactive Nitrogen ◽  
Oxygen Species ◽  
Nitrogen Species ◽  
Radical Species ◽  
Physiological Level

Maintaining the physiological level of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the body is highly important in the fight against radical species in the context of human health [...]

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