Direct determination of trace nitrogen dioxide by atmospheric pressure lonization mass spectrometry (APIMS) without conversion to nitric oxide

Abstract

The aim of this study was to develop a new method for the determination of NOz levels encountered in clinical settings as well as in environmental studies, using a bi-component atmospheric pressure ionization mass spectrometry (APIMS). Hydrogen (1%) diluted in pure argon was ionized by corona discharge in the first ionization component. Fifty ml of the analyte diluted in 250 ml of composite air or carbon dioxide (COz) was introduced into the second ionization component and analyzed. When composite air was used as the sample carrier gas, NO in the analyte was oxygenated and there was an increase in the NO2 content from that in the original analyte. However, when COa was used as the sample carrier gas, the level of NOz in the analyte could be determined because COe did not change the NOz content from that in the original analyte. A calibration curve with good linearity was obtained using the UG-410 APIMS system, with a regression equation of Y(%) = 5.513"10 e X (ppb) and a detection limit of 0.9 ppb. Since APIMS detects NOz directly within its system, the concentration of NO does not need to be measured. This system may be of great help in the accurate detection and determination of the concentration of low levels of NOz during inhaled NO therapy.

Electrochemical Ammonia Generation Directly from Nitrogen and Air Using an Iron-Oxide/Titania-Based Catalyst at Ambient Conditions

“…At this applied potential, three gases were detected in a large window of mass-to-charge ratios ( m / z ), that is, m / z values of 2, 17, and 32 (corresponding to hydrogen, ammonia, and oxygen, respectively). The simultaneous ammonia electro-oxidation that might take place on the counter electrode was ruled out because no peaks that correspond to either NO or NO 2 ( m / z = 30) were found in the spectrum at this applied potential . These oxides could have been formed on the anodic electrode as a side product in the oxidation of ammonia and water to N 2 and O 2 , respectively.…”

“…The simultaneous ammonia electro-oxidation that might take place on the counter electrode was ruled out because no peaks that correspond to either NO or NO 2 (m/z = 30) were found in the spectrum at this applied potential. 41 These oxides could have been formed on the anodic electrode as a side product in the oxidation of ammonia and water to N 2 and O 2 , respectively. We attributed this to the relatively high overpotential of ammonia oxidation on Ni foil (as seen in Figure S1).…”

Electrical detection of ppb region NO2 using Mg-porphyrin-modified graphene field-effect transistors

“…The use of gas chromatography and mass spectrometry for typical identification of trace harmful gases is one of the examples of a complex method. 8,9 As a result, such conventional methods are not suitable for onsite and real-time measurements in applications in the abovementioned fields. Thus, the detection of NO2 at the ppb level in ambient air using small devices is necessary.…”

Photocatalytic Conversion of Nitric Oxide on Titanium Dioxide: Cryotrapping of Reaction Products for Online Monitoring by Mass Spectrometry

“…18,19 Most of the previously reported studies on conversion of NO x gases have employed various spectroscopic (e.g., infrared (IR), 20 laser absorption, 21 and chemiluminescence (CL) 22 ) or electrochemical techniques 23 for detection of NO x reaction products. The use of gas chromatography (GC) systems equipped with electron capture detectors (ECDs) 24 or mass spectrometers (MS) 25,26 for identification of NO x reaction products have been previously reported. In addition, biomedical applications of NO detection, by using high resolution MS 27 and, indirectly, semiconducting metal oxides, 28 have been reported.…”

“…Photocatalytic efficiencies of TiO 2 catalysts depend on their crystalline phases, surface morphologies, specific surface areas, electronic structures, and thermal treatments. , To achieve peak catalytic performance, optimizations of these parameters are necessary. , Most of the previously reported studies on conversion of NO x gases have employed various spectroscopic (e.g., infrared (IR), laser absorption, and chemiluminescence (CL)) or electrochemical techniques for detection of NO x reaction products. The use of gas chromatography (GC) systems equipped with electron capture detectors (ECDs) or mass spectrometers (MS) , for identification of NO x reaction products have been previously reported. In addition, biomedical applications of NO detection, by using high resolution MS and, indirectly, semiconducting metal oxides, have been reported.…”