scholarly journals Evaluation of the VOC pollution pattern and emission characteristics during the Beijing resurgence of COVID-19 in summer 2020 based on the measurement of PTR-ToF-MS

2021 ◽  
Author(s):  
Zhining Zhang ◽  
Hanyang Man ◽  
Fengkui Duan ◽  
Zhaofeng lv ◽  
Songxin Zheng ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Industrial Process ◽  
Proton Transfer Reaction ◽  
Control Measures ◽  
Emission Characteristics ◽  
Mixing Ratios ◽  
Flight Mass Spectrometry ◽  
Dynamic Source ◽  
Tof Ms ◽  
Observation Period

Abstract A second wave of coronavirus disease 2019 (COVID-19) infections have emerged in summer Beijing, 2020, which provided an opportunity to explore the response of air pollution to reduced human activity. Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) coupled with Positive Matrix Factorization (PMF) source apportionment were applied to evaluate the pollution pattern and capture the detailed dynamic emission characteristics of volatile organic compounds (VOCs) during the representative period with the occurrence of O3 pollution episodes and the Beijing resurgence of COVID-19. The level of anthropogenic VOC was lower than the same period of previous years due to the pandemic and emission reduction measures. More than two-thirds of the observation period were identified as high-O3 days and VOCs exhibited higher mixing ratios and faster consumption rates in the daytime under high-O3 days. The identified VOC emission sources and the corresponding contributions during the whole observation period included: vehicle + fuel (12.41 ± 9.43%), industrial process (9.40 ± 8.65%), solvent usage (19.58 ± 13.46%), biogenic (6.03 ± 5.40%), background + long-lived (5.62 ± 11.37%), and two groups of oxygenated VOC (OVOC) factors (primary emission and secondary formation, 26.14 ± 15.20% and 20.84 ± 14.0%, respectively). Refined dynamic source apportionment results show that the “stay at home” tendency led to decreased emission (- 34.47 ± 1.90 %) and weakened morning peak of vehicle + fuel during the Beijing resurgence. However, growing emission of primary OVOCs (+ 51.10 ± 8.28%) with similar diurnal variation was observed in the new outbreak and afterwards, which might be related to the enhanced usage of pandemic products. The present study illustrated that more stringent VOC reduction measures towards pandemic products should be carried out to achieve the balanced emission abatement of NOx and VOC when adhering to regular epidemic prevention and control measures.

scholarly journals Rapid Profiling of the Volatilome of Cooked Meat by PTR-ToF-MS: Underlying Latent Explanatory Factors

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1738 ◽  
Author(s):  
Giovanni Bittante ◽  
Qianlin Ni ◽  
Iuliia Khomenko ◽  
Luigi Gallo ◽  
Franco Biasioli
Keyword(s):  
Proton Transfer Reaction ◽  
Multivariate Statistical ◽  
Flight Mass Spectrometry ◽  
Explanatory Factors ◽  
The Matrix ◽  
Sources Of Variation ◽  
Cooked Meat ◽  
Negative Relationships ◽  
Pearson Correlations ◽  
Tof Ms

Volatile organic compounds (VOCs) are important contributors to meat aroma and are variably correlated with each other. To study the sources of variation and the correlations among meat VOCs, meat cuts from five animal species/categories (chicken, turkey, pork, veal, and beef; two animals/species/retailer: 100 meat cuts) were obtained by 10 retailers. Each cut was processed into four burgers, two of which were grilled and two were cooked in a water bath (400 meat burgers). VOCs were detected by Proton-Transfer-Reaction Time-of-Flight Mass-Spectrometry (PTR-ToF-MS). From these, 129 peaks were selected, of which 72 were tentatively identified as relevant VOCs. Pearson correlations revealed a large number of positive and negative relationships among the VOCs. A multivariate statistical analysis revealed that 87% of the matrix covariance was explained by 17 independent Latent Explanatory Factors (LEFs), which have been described and characterized. LEFs identified may be valuable tools for reducing the dimensionality of results from VOC analyses and can be useful for better understanding and interpreting the variation in the meat aroma profile, although further study is required to characterize their sensory meaning.

scholarly journals PTR-TOF-MS eddy covariance measurements of isoprene and monoterpene fluxes from an eastern Amazonian rainforest

2020 ◽  
Vol 20 (12) ◽  
pp. 7179-7191 ◽  
Author(s):  
Chinmoy Sarkar ◽  
Alex B. Guenther ◽  
Jeong-Hoo Park ◽  
Roger Seco ◽  
Eliane Alves ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Atmospheric Chemistry ◽  
Sensible Heat Flux ◽  
Proton Transfer Reaction ◽  
Strongly Correlated ◽  
Mixing Ratios ◽  
Flux Measurements ◽  
Eddy Covariance Measurements ◽  
Emission Models ◽  
Tof Ms

Abstract. Biogenic volatile organic compounds (BVOCs) are important components of the atmosphere due to their contribution to atmospheric chemistry and biogeochemical cycles. Tropical forests are the largest source of the dominant BVOC emissions (e.g. isoprene and monoterpenes). In this study, we report isoprene and total monoterpene flux measurements with a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) using the eddy covariance (EC) method at the Tapajós National Forest (2.857∘ S, 54.959∘ W), a primary rainforest in eastern Amazonia. Measurements were carried out from 1 to 16 June 2014, during the wet-to-dry transition season. During the measurement period, the measured daytime (06:00–18:00 LT) average isoprene mixing ratios and fluxes were 1.15±0.60 ppb and 0.55±0.71 mg C m−2 h−1, respectively, whereas the measured daytime average total monoterpene mixing ratios and fluxes were 0.14±0.10 ppb and 0.20±0.25 mg C m−2 h−1, respectively. Midday (10:00–14:00 LT) average isoprene and total monoterpene mixing ratios were 1.70±0.49 and 0.24±0.05 ppb, respectively, whereas midday average isoprene and monoterpene fluxes were 1.24±0.68 and 0.46±0.22 mg C m−2 h−1, respectively. Isoprene and total monoterpene emissions in Tapajós were correlated with ambient temperature and solar radiation. Significant correlation with sensible heat flux, SHF (r2=0.77), was also observed. Measured isoprene and monoterpene fluxes were strongly correlated with each other (r2=0.93). The MEGAN2.1 (Model of Emissions of Gases and Aerosols from Nature version 2.1) model could simulate most of the observed diurnal variations (r2=0.7 to 0.8) but declined a little later in the evening for both isoprene and total monoterpene fluxes. The results also demonstrate the importance of site-specific vegetation emission factors (EFs) for accurately simulating BVOC fluxes in regional and global BVOC emission models.

scholarly journals Effects of modular ion-funnel technology onto analysis of breath VOCs by means of real-time mass spectrometry

2020 ◽  
Vol 412 (26) ◽  
pp. 7131-7140
Author(s):  
Giovanni Pugliese ◽  
Felix Piel ◽  
Phillip Trefz ◽  
Philipp Sulzer ◽  
Jochen K. Schubert ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Real Time ◽  
Human Subjects ◽  
Proton Transfer Reaction ◽  
Mass Analyzer ◽  
Real Time Monitoring ◽  
Healthy Human ◽  
Flight Mass Spectrometry ◽  
Ion Funnel ◽  
Tof Ms

Abstract Proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a powerful tool for real-time monitoring of trace concentrations of volatile organic compounds (VOCs). The sensitivity of PTR-ToF-MS also depends on the ability to effectively focus and transmit ions from the relatively high-pressure drift tube (DT) to the low-pressure mass analyzer. In the present study, a modular ion-funnel (IF) is placed adjacent to the DT of a PTR-ToF-MS instrument to improve the ion-focusing. IF consists of a series of electrodes with gradually decreasing orifice diameters. Radio frequency (RF) voltage and direct current (DC) electric field are then applied to the electrodes to get the ions focused. We investigated the effect of the RF voltage and DC field on the sensitivity of a pattern of VOCs including hydrocarbons, alcohols, aldehydes, ketones, and aromatic compounds. In a proof-of-concept study, the instrument operating both as normal DT (DC-mode) and at optimal IF conditions (RF-mode) was applied for the breath analysis of 21 healthy human subjects. For the range of investigated VOCs, an improvement of one order of magnitude in sensitivity was observed in RF-mode compared with DC-mode. Limits of detection could be improved by a factor of 2–4 in RF-mode compared with DC-mode. Operating the instrument in RF-mode allowed the detection of more compounds in the exhaled air compared with DC-mode. Incorporation of the IF considerably improved the performance of PTR-ToF-MS allowing the real-time monitoring of a larger number of potential breath biomarkers.

scholarly journals Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and off-line GC-FID

2015 ◽  
Vol 8 (12) ◽  
pp. 13157-13197
Author(s):  
V. Perraud ◽  
S. Meinardi ◽  
D. R. Blake ◽  
B. J. Finlayson-Pitts
Keyword(s):  
Real Time ◽  
Dimethyl Sulfide ◽  
Dimethyl Disulfide ◽  
Proton Transfer Reaction ◽  
Organosulfur Compounds ◽  
Negative Effects ◽  
Flight Mass Spectrometry ◽  
Sampling Systems ◽  
Animal Metabolism ◽  
Tof Ms

Abstract. Organosulfur compounds (OSC) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to have negative effects on visibility, climate and human health. In order to predict particle formation events, accurate measurements of the OSC precursors are essential. Here, two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled with GC-FID are compared for both laboratory standards [dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and methanethiol (MTO)] and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air.

scholarly journals Assessment Wine Aroma Persistence by Using an in Vivo PTR-ToF-MS Approach and Its Relationship with Salivary Parameters

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1277 ◽  
Author(s):  
Carolina Muñoz-González ◽  
Francis Canon ◽  
Gilles Feron ◽  
Elisabeth Guichard ◽  
Maria Pozo-Bayón
Keyword(s):  
Nasal Cavity ◽  
Salivary Flow ◽  
Proton Transfer Reaction ◽  
Total Protein Content ◽  
Wine Aroma ◽  
Flight Mass Spectrometry ◽  
Analytical Perspective ◽  
Positive Correlations ◽  
Tof Ms

To better understand wine aroma persistence, the nasal cavity of nine volunteers was monitored by Proton Transfer Reaction-Time of Flight-Mass Spectrometry (PTR-ToF-MS) after they rinsed their mouths with three rosé wines (one control and the same wine supplemented with two tannin extracts) during four minutes. Wines were aromatised with a mixture of five target aroma compounds. Results showed that wine aroma persistence was highly compound-dependent: while esters disappeared very fast, other compounds such as linalool remained in the oral cavity for longer times after wine expectoration. A low effect of tannins (at 50 mg/L) on nasal cavity parameters was observed, with the exception for the compound ethyl decanoate that was significantly higher released in the presence of tannins. Strong interindividual differences on aroma persistence were also found. Significant positive correlations with the salivary total protein content and negative with the salivary flow were observed for specific compounds. This work has studied for the first time in vivo wine aroma persistence in real time from an analytical perspective.

scholarly journals Contribution of Terpenes to Ozone Formation and Secondary Organic Aerosols in a Subtropical Forest Impacted by Urban Pollution

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1232
Author(s):  
Christian Mark Salvador ◽  
Charles C.-K. Chou ◽  
Tse-Tsung Ho ◽  
Chao-Yang Tsai ◽  
Tsung-Ming Tsao ◽  
...  
Keyword(s):  
Urban Pollution ◽  
Proton Transfer Reaction ◽  
Subtropical Forest ◽  
Oxidation Products ◽  
Ozone Formation ◽  
Particle Phase ◽  
Spectra Analysis ◽  
Gas Phases ◽  
Mixing Ratios ◽  
Tof Ms

The highly reactive nature of biogenic volatile organic compounds (BVOCs) impacts the biosphere by acting as a precursor of ozone and aerosols that influence air quality and climate. Here, we assess the influence of BVOCs and their oxidation products on ozone formation and to submicron secondary organic aerosol (SOA) mass in a subtropical forest. A high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) was employed for the continuous measurement of VOCs. Isoprene, monoterpene, and sesquiterpene mixing ratios in the forest were 0.23, 0.22, and 0.03 ppb, respectively. The total ozone formation potential (OFP) of the terpenes was 12.8 μg m−3, which accounted for only 5.6% of the total OFP. Particle phase bound oxidation products were characterized using a thermal-desorption PTR-ToF-MS. Mass spectra analysis revealed the presence pinonaldehyde, pinonic, norpinonic, and pinic acid in both gas and particle phase. The overall daytime (nighttime) mixing ratio of the oxidized BVOCs in gas phases was 0.062(0.023) ppbv. On the other hand, the mean fraction of the four monoterpene oxidation products in condensed phase was estimated at 42%. Overall, the results of this study evidenced quantitatively the contribution of BVOCs to the total reactivity and SOA mass in the subtropical forest.

Smokers Breath as Seen by Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS)

2013 ◽  
pp. 89-116 ◽  
Author(s):  
Ingrid Kohl ◽  
Jens Herbig ◽  
Jürgen Dunkl ◽  
Armin Hansel ◽  
Martin Daniaux ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Reaction Time ◽  
Proton Transfer ◽  
Transfer Reaction ◽  
Time Of Flight ◽  
Proton Transfer Reaction ◽  
Flight Mass Spectrometry ◽  
Tof Ms

scholarly journals Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and offline GC-FID

2016 ◽  
Vol 9 (3) ◽  
pp. 1325-1340 ◽  
Author(s):  
Véronique Perraud ◽  
Simone Meinardi ◽  
Donald R. Blake ◽  
Barbara J. Finlayson-Pitts
Keyword(s):  
Real Time ◽  
Dimethyl Sulfide ◽  
Dimethyl Disulfide ◽  
Proton Transfer Reaction ◽  
Organosulfur Compounds ◽  
Flame Ionization ◽  
Flight Mass Spectrometry ◽  
Animal Metabolism ◽  
Negative Impacts ◽  
Tof Ms

Abstract. Organosulfur compounds (OSCs) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism, and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to influence clouds and climate, atmospheric chemical processes. In addition, particles in air have been linked to negative impacts on visibility and human health. Accurate measurements of the OSC precursors are thus essential to reduce uncertainties in their sources and contributions to particle formation in air. Two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled to gas chromatography with flame ionization detector (GC-FID), are compared for both laboratory standards (dimethyl sulfide, DMS; dimethyl disulfide, DMDS; dimethyl trisulfide, DMTS; and methanethiol, MTO) and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS, and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air.

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