scholarly journals Technical Note: Determination of formaldehyde mixing ratios in polluted air with PTR-MS: laboratory experiments and field measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 12845-12876
Author(s):  
S. Inomata ◽  
H. Tanimoto ◽  
S. Kameyama ◽  
U. Tsunogai ◽  
H. Irie ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Detection Sensitivity ◽  
Optical Absorption Spectroscopy ◽  
High Time Resolution ◽  
Mixing Ratios ◽  
Proton Transfer Reactions ◽  
Humidity Dependence

Abstract. Formaldehyde (HCHO), the most abundant carbonyl compound in the atmosphere, is generated as an intermediate product in the oxidation of nonmethane hydrocarbons. Proton transfer reaction mass spectrometry (PTR-MS) has the capability to detect HCHO from ion signals at m/z 31 with high time-resolution. However, the detection sensitivity is low compared to other detectable species, and is considerably affected by humidity, due to back reactions between protonated HCHO and water vapor prior to analysis. We performed a laboratory calibration of HCHO by PTR-MS and examined the detection sensitivity and humidity dependence at various field strengths. Subsequently, we deployed the PTR-MS instrument in a field campaign at Mount Tai in China in June 2006 to measure HCHO in various meteorological and photochemical conditions; we also conducted intercomparison measurements by Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). Correction of interference in the m/z 31 signals by fragments from proton transfer reactions with methyl hydroperoxide, methanol, and ethanol greatly improves agreement between the two methods, giving the correlation [HCHO]MAX-DOAS = (0.99±0.16) [HCHO]PTR-MS + (0.02±0.38), where error limits represent 95% confidence levels.

scholarly journals Technical Note: Determination of formaldehyde mixing ratios in air with PTR-MS: laboratory experiments and field measurements

2008 ◽  
Vol 8 (2) ◽  
pp. 273-284 ◽  
Author(s):  
S. Inomata ◽  
H. Tanimoto ◽  
S. Kameyama ◽  
U. Tsunogai ◽  
H. Irie ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Detection Sensitivity ◽  
Optical Absorption Spectroscopy ◽  
High Time Resolution ◽  
Mixing Ratios ◽  
Proton Transfer Reactions ◽  
Humidity Dependence

Abstract. Formaldehyde (HCHO), the most abundant carbonyl compound in the atmosphere, is generated as an intermediate product in the oxidation of nonmethane hydrocarbons. Proton transfer reaction mass spectrometry (PTR-MS) has the capability to detect HCHO from ion signals at m/z 31 with high time-resolution. However, the detection sensitivity is low compared to other detectable species, and is considerably affected by humidity, due to back reactions between protonated HCHO and water vapor prior to analysis. We performed a laboratory calibration of PTR-MS for HCHO and examined the detection sensitivity and humidity dependence at various field strengths. Subsequently, we deployed the PTR-MS instrument in a field campaign at Mount Tai in China in June 2006 to measure HCHO in various meteorological and photochemical conditions; we also conducted intercomparison measurements by Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). Correction of interference in the m/z 31 signals by fragments from proton transfer reactions with methyl hydroperoxide, methanol, and ethanol greatly improves agreement between the two methods, giving the correlation [HCHO]MAX-DOAS=(0.99±0.16) [HCHO]PTR-MS+(0.02±0.38), where error limits represent 95% confidence levels.

scholarly journals Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS – measurement, calibration, and volume mixing ratio calculation methods

2008 ◽  
Vol 8 (22) ◽  
pp. 6681-6698 ◽  
Author(s):  
R. Taipale ◽  
T. M. Ruuskanen ◽  
J. Rinne ◽  
M. K. Kajos ◽  
H. Hakola ◽  
...  
Keyword(s):  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Transmission Curve ◽  
Mixing Ratio ◽  
Calculation Methods ◽  
Mixing Ratios ◽  
Ratio Calculation ◽  
Gas Standard

Abstract. Proton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). This paper gives a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. The PTR-MS instrument has to be calibrated regularly with a gas standard to ensure the accuracy needed in atmospheric VOC measurements. We introduce a novel method for determining an instrument specific relative transmission curve using information obtained from a calibration. This curve enables consistent mixing ratio calculation for VOCs not present in a calibration gas standard. Our method proved to be practical, systematic, and sensitive enough to capture changes in the transmission over time. We also propose a new approach to considering the abundance of H3O+H2O ions in mixing ratio calculation. The approach takes into account the difference in the transmission efficiencies for H3O+ and H3O+H2O ions. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March–26 April 2007, the hourly averages of the mixing ratios were 0.051–0.57 ppbv for formaldehyde, 0.19–3.1 ppbv for methanol, 0.038–0.39 ppbv for benzene, and 0.020–1.3 ppbv for monoterpenes. The detection limits for the hourly averages were 0.020, 0.060, 0.0036, and 0.0092 ppbv, respectively.

scholarly journals Technical Note: Quantitative long-term measurements of VOC concentrations by PTR-MS – measurement, calibration, and volume mixing ratio calculation methods

2008 ◽  
Vol 8 (3) ◽  
pp. 9435-9475 ◽  
Author(s):  
R. Taipale ◽  
T. M. Ruuskanen ◽  
J. Rinne ◽  
M. K. Kajos ◽  
H. Hakola ◽  
...  
Keyword(s):  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Transmission Curve ◽  
Mixing Ratio ◽  
Calculation Methods ◽  
Mixing Ratios ◽  
Ratio Calculation ◽  
Online Measurements

Abstract. Proton transfer reaction mass spectrometry (PTR-MS) is a technique for online measurements of atmospheric concentrations, or volume mixing ratios, of volatile organic compounds (VOCs). The aim of this paper is to give a detailed description of our measurement, calibration, and volume mixing ratio calculation methods, which have been designed for long-term stand-alone field measurements by PTR-MS. We also show how the information obtained from a calibration can be used to determine the instrument specific relative transmission curve, which enables quantitative mixing ratio calculation for VOCs which are not present in a calibration gas standard. To illustrate the functionality of our measurement, calibration, and calculation methods, we present a one-month period of ambient mixing ratio data measured in a boreal forest ecosystem at the SMEAR II station in southern Finland. During the measurement period 27 March–26 April 2007, the hourly averages of mixing ratios were 0.1–0.5 ppbv for formaldehyde, 0.2–3.0 ppbv for methanol, 0.04–0.39 ppbv for benzene, and 0.03–1.25 ppbv for monoterpenes.

Intermolecular proton shuttling in excited state proton transfer reactions: insights from theory

2014 ◽  
Vol 16 (18) ◽  
pp. 8661-8666 ◽  
Author(s):  
Marika Savarese ◽  
Paolo A. Netti ◽  
Nadia Rega ◽  
Carlo Adamo ◽  
Ilaria Ciofini
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Transfer Reactions ◽  
Td Dft ◽  
Excited State Proton Transfer ◽  
Proton Transfer Reactions ◽  
Proton Shuttling

The mechanism of intermolecular proton shuttling involved in a prototypical excited state proton transfer reaction is disclosed using DFT and TD-DFT.

scholarly journals Long-term study of VOCs measured with PTR-MS at a rural site in New Hampshire with urban influences

2009 ◽  
Vol 9 (1) ◽  
pp. 4251-4299
Author(s):  
C. Jordan ◽  
E. Fitz ◽  
T. Hagan ◽  
B. Sive ◽  
E. Frinak ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Proton Transfer Reaction ◽  
Early Morning ◽  
Rural Site ◽  
High Time Resolution ◽  
Data Set ◽  
Mixing Ratios ◽  
Long Term Study ◽  
Urban Rural

Abstract. A long-term, high time-resolution volatile organic compound (VOC) data set from a ground site that experiences urban, rural, and marine influences in the northeastern United States is presented. A proton-transfer-reaction mass spectrometer (PTR-MS) was used to quantify 15 VOCs: a marine tracer dimethyl sulfide (DMS), a biomass burning tracer acetonitrile, biogenic compounds (monoterpenes, isoprene), oxygenated VOCs (OVOCs: methyl vinyl ketone (MVK) plus methacrolein (MACR), methanol, acetone, methyl ethyl ketone (MEK), acetaldehyde, and acetic acid), and aromatic compounds (benzene, toluene, C8 and C9 aromatics). Time series, overall and seasonal medians, with 10th and 90th percentiles, seasonal mean diurnal profiles, and inter-annual comparisons of mean summer and winter diurnal profiles are shown. Methanol and acetone exhibit the highest overall median mixing ratios 1.44 and 1.02 ppbv, respectively. Comparing the mean diurnal profiles of less well understood compounds (e.g., MEK) with better known compounds (e.g., isoprene, monoterpenes, and MVK+MACR) that undergo various controls on their atmospheric mixing ratios provides insight into possible sources of the lesser known compounds. The constant diurnal value of ≈0.7 for the toluene:benzene ratio in winter, may possibly indicate the influence of wood-based heating systems in this region. Methanol exhibits an initial early morning release in summer unlike any other OVOC (or isoprene) and a dramatic late afternoon mixing ratio increase in spring. Although several of the OVOCs appear to have biogenic sources, differences in features observed between isoprene, methanol, acetone, acetaldehyde, and MEK suggest they are produced or emitted in unique ways.

scholarly journals Formaldehyde measurements by Proton transfer reaction – Mass Spectrometry (PTR-MS): correction for humidity effects

2010 ◽  
Vol 3 (4) ◽  
pp. 1055-1062 ◽  
Author(s):  
A. Vlasenko ◽  
A .M. Macdonald ◽  
S. J. Sjostedt ◽  
J. P. D. Abbatt
Keyword(s):  
Mass Spectrometry ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Ambient Air ◽  
Proton Transfer Reaction ◽  
Photochemical Activity ◽  
Reaction Mass ◽  
Good Time ◽  
Humidity Dependence ◽  
Instrument Sensitivity

Abstract. Formaldehyde measurements can provide useful information about photochemical activity in ambient air, given that HCHO is formed via numerous oxidation processes. Proton transfer reaction mass spectrometry (PTR-MS) is an online technique that allows measurement of VOCs at the sub-ppbv level with good time resolution. PTR-MS quantification of HCHO is hampered by the humidity dependence of the instrument sensitivity, with higher humidity leading to loss of PTR-MS signal. In this study we present an analytical, first principles approach to correct the PTR-MS HCHO signal according to the concentration of water vapor in sampled air. The results of the correction are validated by comparison of the PTR-MS results to those from a Hantzsch fluorescence monitor which does not have the same humidity dependence. Results are presented for an intercomparison made during a field campaign in rural Ontario at Environment Canada's Centre for Atmospheric Research Experiments.

Electron and hole interactions with P, Z, and P:Z and the formation of mutagenic products by proton transfer reactions

2020 ◽  
Vol 22 (2) ◽  
pp. 919-931
Author(s):  
N. R. Jena
Keyword(s):  
Proton Transfer ◽  
Electron Acceptor ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Transfer Reactions ◽  
Proton Transfer Reactions

Z would act as an electron acceptor and P would capture a hole in the unnatural DNA. The latter process would produce mutagenic products via a proton transfer reaction.

scholarly journals Field measurements of methylglyoxal using proton transfer reaction time-of-flight mass spectrometry and comparison to the DNPH–HPLC–UV method

2018 ◽  
Vol 11 (10) ◽  
pp. 5729-5740 ◽  
Author(s):  
Vincent Michoud ◽  
Stéphane Sauvage ◽  
Thierry Léonardis ◽  
Isabelle Fronval ◽  
Alexandre Kukui ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Reaction Time ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Time Of Flight ◽  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Atmospheric Measurements ◽  
Flight Mass Spectrometry ◽  
Tof Ms

Abstract. Methylglyoxal (MGLY) is an important atmospheric α-dicarbonyl species for which photolysis acts as a significant source of peroxy radicals, contributing to the oxidizing capacity of the atmosphere and, as such, the formation of secondary pollutants such as organic aerosols and ozone. However, despite its importance, only a few techniques exhibit time resolutions and detection limits that are suitable for atmospheric measurements. This study presents the first field measurements of MGLY by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) performed during the ChArMEx SOP2 field campaign. This campaign took place at a Mediterranean site characterized by intense biogenic emissions and low levels of anthropogenic trace gases. Concomitant measurements of MGLY were performed using the 2,4-dinitrophenylhydrazine (DNPH) derivatization technique and high performance liquid chromatography (HPLC) with UV detection. PTR-ToF-MS and DNPH–HPLC measurements were compared to determine whether these techniques can perform reliable measurements of MGLY. Ambient time series revealed levels of MGLY ranging from 28 to 365 pptv, with a clear diurnal cycle due to elevated concentrations of primary biogenic species during the daytime, and its oxidation led to large production rates of MGLY. A scatter plot of the PTR-ToF-MS and DNPH–HPLC measurements indicates a reasonable correlation (R2=0.48) but a slope significantly lower than unity (0.58±0.05) and a significant intercept of 88.3±8.0 pptv. A careful investigation of the differences between the two techniques suggests that this disagreement is not due to spectrometric interferences from H3O+(H2O)3 or methyl ethyl ketone (or butanal) detected at m∕z 73.050 and m∕z 73.065, respectively, which are close to the MGLY m∕z of 73.029. The differences are more likely due to uncorrected sampling artifacts such as overestimated collection efficiency or loss of MGLY into the sampling line for the DNPH–HPLC technique or unknown isobaric interfering compounds such as acrylic acid and propanediol for the PTR-ToF-MS. Calculations of MGLY loss rates with respect to OH oxidation and direct photolysis indicate similar contributions for these two loss pathways.

Kinetic study of the proton transfer reaction between 1-nitro-1-(4-nitrophenyl)alkanes and TBD and MTBD bases in acetonitrile solvent

2001 ◽  
Vol 79 (7) ◽  
pp. 1128-1134 ◽  
Author(s):  
Iwona Grzeskowiak ◽  
Wtodzimierz Galezowski ◽  
Arnold Jarczewski
Keyword(s):  
Proton Transfer ◽  
Kinetic Study ◽  
Transfer Reaction ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Kinetic Isotope Effects ◽  
Proton Transfer Reaction ◽  
Comparable Amount ◽  
Kinetic Isotope ◽  
Proton Transfer Reactions

The rates of proton transfer reactions between C-acids of the series of nitroalkanes with increasing bulk of R = H, Me, Et, i-Pr substituent as: 4-nitrophenylnitromethane (0), 1-(4-nitrophenyl)-1-nitroethane (1), 1-(4-nitrophenyl)-1-nitropropane (2), 2-methyl-1-(4-nitrophenyl)-1-nitropropane (3) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) have been measured in acetonitrile at pseudo-first-order conditions. The product of the proton transfer reaction with MTBD in acetonitrile is dissociated into free ions while that of the TBD reaction is composed of a comparable amount of ions and ion pairs. The second-order rate constants (k2H) for these bases of almost equal strength in acetonitrile (pKa = 24.70, 24.97 for MTBD and TBD) and C-acids 1, 2, and 3 are: 317, 86, 7.6 dm3 mol–1 s–1; and 15 200, 5300, 1100 dm3 mol–1 s–1, respectively. The appropriate primary deuterium kinetic isotope effects (kH/kD) are 12.5, 10.8, 6.9; and 9.9, 11.2, 12.6. The influence of steric hindrance brought by reacting C-acids and bases is discussed. The different structure of the transition states and the products as mono- and double-hydrogen bonded complexes for these series of C-acids and MTBD and TBD bases is manifested by a distinct reaction mechanism which we attempt to explain.Key words: proton transfer, kinetic study, C-acids, organic bases, acetonitrile, kinetic isotope effects.

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