Chemosphere, Journal Year: 2024, Volume and Issue: 363, P. 142846 - 142846
Published: July 19, 2024
Language: Английский
Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(4), P. 1635 - 1679
Published: Jan. 11, 2023
Organic peroxides (POs) are organic molecules with one or more peroxide (−O–O−) functional groups. POs commonly regarded as chemically labile termination products from gas-phase radical chemistry and therefore serve temporary reservoirs for oxidative radicals (HOx ROx) in the atmosphere. Owing to their ubiquity, active gas-particle partitioning behavior, reactivity, key reactive intermediates atmospheric multiphase processes determining life cycle (formation, growth, aging), climate, health impacts of aerosol. However, there remain substantial gaps origin, molecular diversity, fate due complex nature dynamic behavior. Here, we summarize current understanding on POs, a focus identification quantification, state-of-the-art analytical developments, molecular-level formation mechanisms, chemical transformation pathways, well environmental impacts. We find that interactions SO2 transition metal ions generally fast PO pathways liquid water, lifetimes estimated be minutes hours, while hydrolysis is particularly important α-substituted hydroperoxides. Meanwhile, photolysis thermolysis likely minor sinks POs. These distinctly different fates, such reaction OH radicals, which highlights need understand By summarizing advances remaining challenges investigation propose future research priorities regarding fate,
Language: Английский
Citations
93
Proceedings of the National Academy of Sciences, Journal Year: 2023, Volume and Issue: 120(10)
Published: Feb. 27, 2023
Hydroperoxides are formed in the atmospheric oxidation of volatile organic compounds, combustion autoxidation fuel, cold environment interstellar medium, and also some catalytic reactions. They play crucial roles formation aging secondary aerosols fuel autoignition. However, concentration hydroperoxides is seldom measured, typical estimates have large uncertainties. In this work, we developed a mild environmental-friendly method for synthesis alkyl (ROOH) with various structures, systematically measured absolute photoionization cross-sections (PICSs) ROOHs using synchrotron vacuum ultraviolet-photoionization mass spectrometry (SVUV-PIMS). A chemical titration was combined an SVUV-PIMS measurement to obtain PICS 4-hydroperoxy-2-pentanone, molecule ketohydroperoxides (KHPs). We found that hydroperoxide cations largely dissociated by loss OOH. This fingerprint used identification accurate quantification peroxides, it can therefore be improve models chemistry. The dataset useful studying chemistry reaction kinetics hydroperoxy radicals developing evaluating kinetic compounds.
Language: Английский
Citations
27
The Science of The Total Environment, Journal Year: 2024, Volume and Issue: 919, P. 170836 - 170836
Published: Feb. 10, 2024
Language: Английский
Citations
11
Mass Spectrometry Reviews, Journal Year: 2023, Volume and Issue: 43(5), P. 1091 - 1134
Published: July 13, 2023
Abstract The Earth's atmosphere is composed of an enormous variety chemical species associated with trace gases and aerosol particles whose composition chemistry have critical impacts on the climate, air quality, human health. Mass spectrometry analysis as a powerful popular analytical technique has been widely developed applied in atmospheric for decades. allows effective detection, identification, quantification broad range organic inorganic high sensitivity resolution. In this review, we summarize recently mass techniques, methods, applications research past several years molecular‐level. Specifically, new developments ion‐molecule reactors, various soft ionization unique coupling separation techniques are highlighted. laboratory studies field measurements focused improving detection limits traditional emerging volatile compounds, characterizing multiphase highly oxygenated molecules, monitoring particle bulk surface compositions.
Language: Английский
Citations
20
ACS Earth and Space Chemistry, Journal Year: 2023, Volume and Issue: 7(1), P. 218 - 229
Published: Jan. 5, 2023
Cyclic volatile methyl siloxanes (cVMS) that are emitted from industrial processes and consumer products often dominate the burden of organic compounds (VOCs) in occupied spaces. cVMS may contribute to oxygenated VOC secondary aerosol (SOA) formation following oxidation by gas-phase radicals both indoor outdoor source regions. Several recent studies examined SOA potential decamethylcyclopentasiloxane (D5) exposure hydroxyl (OH) found this reaction generates high yield multiple days oxidative aging. Chlorine atoms (Cl) compete with OH for loss D5 regions active chlorine chemistry, but + Cl reactions has not been studied. Here, we characterized chemical composition generated an flow reactor (OFR) under dry [relative humidity (RH) < 5%] humid (RH = 40%) conditions compared results D5. was oxidized using integrated exposures (OHexp Clexp) ranging 1.1 × 1012 8.2 cm–3 s 1.6 1010 s, respectively. Like OH, facilitated multistep aging over range OFR were studied, maximum mass yields 1.5 1.3 obtained conditions. These suggest significantly influenced chemistry enhance atmospheric
Language: Английский
Citations
19
Atmospheric measurement techniques, Journal Year: 2024, Volume and Issue: 17(8), P. 2415 - 2427
Published: April 23, 2024
Abstract. Volatile organic compounds (VOCs) affect secondary pollutant formation via active chemistry. Proton-transfer-reaction mass spectrometry (PTR-MS) is one of the most important techniques to study highly variable spatial and temporal characteristics VOCs. The response protonated, adduct, fragmented ions in PTR-MS changing instrument settings varying relative humidity (RH) requires rigorous characterization. Herein, we present dedicatedly designed laboratory experiments conducted investigate these for 21 VOCs, including 12 oxygenated VOCs 2 nitriles, using recently developed Vocus PTR-MS. Our results show that focusing ion–molecule reactor (FIMR) axial voltage increases sensitivity by 3 4 orders magnitude but does not significantly change fractions protonated ions. Reducing FIMR pressure, however, substantially fragmentation. Applying a high radio frequency (RF) amplitude radially can enhance 1 without affecting ion fractions. big segmented quadrupole (BSQ) mainly affects fraction modifying transmission. relationship between proton-transfer reaction rate constant complicated influences from both transmission fraction. studied (19 out 21) less than 15 % variations as RH ∼ 5% 85 %, except some long-chain aldehydes which positive variation up 30 %. suggest reliably quantify majority under ambient conditions with RH. However, caution advised small oxygenates such formaldehyde methanol due their low slight dependence
Language: Английский
Citations
5
Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(5), P. 3147 - 3180
Published: March 10, 2023
Abstract. The gas-phase reaction of isoprene with the nitrate radical (NO3) was investigated in experiments outdoor SAPHIR chamber under atmospherically relevant conditions specifically respect to chemical lifetime and fate nitrato-organic peroxy radicals (RO2). Observations organic products were compared concentrations expected from different mechanisms: (1) Master Chemical Mechanism, which simplifies NO3 chemistry by only considering one RO2 isomer; (2) mechanism derived Caltech chamber, considers isomers; (3) FZJ-NO3 quantum calculations, addition includes equilibrium reactions isomers, unimolecular epoxidation alkoxy radicals. Measurements using mass spectrometer instruments give evidence that new pathways predicted calculations play a role oxidation isoprene. Hydroperoxy aldehyde (HPALD) species, are specific RO2, detected even presence an OH scavenger, excluding possibility concurrent hydroxyl (OH) is responsible for their formation. In addition, ion signals at masses can be attributed epoxy compounds, radicals, detected. methyl vinyl ketone (MVK) methacrolein (MACR) confirm decomposition implemented cannot compete ring-closure calculations. validity further supported good agreement between measured simulated reactivity. Nevertheless, needs investigations absolute importance Absolute nitrates such as hydroperoxides would required experimentally determine product yields branching ratios but could not due lack calibration standards these compounds. temporal evolution traces species hydroperoxides, carbonyl alcohols well hydroperoxy aldehydes observed demonstrates ozone atmospheric small on timescale night (12 h) typical oxidant concentrations. However, present potentially also produced contribute nocturnal loss.
Language: Английский
Citations
12
Published: Jan. 6, 2025
Abstract. Proton-transfer-reaction mass spectrometry (PTR-MS) using hydronium ion (H3O+) ionization is widely used for the measurement of volatile organic compounds (VOCs) both indoors and outdoors. Unlike more energetic methods (e.g., electron impact), H3O+ can leave a target VOC molecule mostly intact thus in PTR-MS spectrum be identified by its mass-to-charge ratio corresponding to proton-transfer product (MH+). However, ionization, associated chemistry reactor, known generate other ions besides product. The distributions (PIDs) created during include resulting from charge transfer reactions, water clustering, fragmentation, all which create ambiguity when interpreting spectra. A standardized method evaluating quantifying possible influence PIDs on spectra limited part due an incomplete understanding formation mechanisms effects instrument settings measured PIDs, as well reasons instrument-to-instrument variability. We present method, gas-chromatography pre-separation, measurements nearly 100 VOCs different functional types including alcohols, ketones, aldehydes, acids, aromatics, halogens, alkenes. Using this we highlight major contributions cluster fragment oxygenated VOCs. characterize ion-molecule reactor conditions, transmission quadrupole optic tuning, inlet capillary configuration PIDs. find that conditions have strongest impact but voltage differences also affect Through interlaboratory comparison calibration cylinders variability PID production same model across seven participating laboratories. subset laboratories had standard deviations (1 σ) with varied no than 20 % providing constraint predicting instruments operating under conditions. potential misidentification case study restroom air. propose identifying likely constraining Finally, library acquired study, publicly available updated periodically user-provided data continued investigation into
Language: Английский
Citations
0
Published: Jan. 6, 2025
Abstract. Proton-transfer-reaction mass spectrometry (PTR-MS) using hydronium ion (H3O+) ionization is widely used for the measurement of volatile organic compounds (VOCs) both indoors and outdoors. Unlike more energetic methods (e.g., electron impact), H3O+ can leave a target VOC molecule mostly intact thus in PTR-MS spectrum be identified by its mass-to-charge ratio corresponding to proton-transfer product (MH+). However, ionization, associated chemistry reactor, known generate other ions besides product. The distributions (PIDs) created during include resulting from charge transfer reactions, water clustering, fragmentation, all which create ambiguity when interpreting spectra. A standardized method evaluating quantifying possible influence PIDs on spectra limited part due an incomplete understanding formation mechanisms effects instrument settings measured PIDs, as well reasons instrument-to-instrument variability. We present method, gas-chromatography pre-separation, measurements nearly 100 VOCs different functional types including alcohols, ketones, aldehydes, acids, aromatics, halogens, alkenes. Using this we highlight major contributions cluster fragment oxygenated VOCs. characterize ion-molecule reactor conditions, transmission quadrupole optic tuning, inlet capillary configuration PIDs. find that conditions have strongest impact but voltage differences also affect Through interlaboratory comparison calibration cylinders variability PID production same model across seven participating laboratories. subset laboratories had standard deviations (1 σ) with varied no than 20 % providing constraint predicting instruments operating under conditions. potential misidentification case study restroom air. propose identifying likely constraining Finally, library acquired study, publicly available updated periodically user-provided data continued investigation into
Language: Английский
Citations
0
Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown
Published: Jan. 16, 2025
While biomass burning (BB) is the largest source of fine particles in atmosphere, influence relative humidity (RH) and photochemistry on BB secondary organic aerosol (BB-SOA) formation aging remains poorly constrained. These effects need to be addressed better capture comprehend evolution BB-SOA atmosphere. Cresol (C7H8O) used as a proxy investigate these effects. It emitted directly from has been identified significant SOA precursor residential wood-burning emissions. The gas- particle-phase signal intensities are investigated using online mass spectrometers. An increase yield 7% observed when RH rises 0.5–20 70–87%. At elevated RH, nitrogen-containing compounds due processes. This linked net decrease viscosity, enabling formed greater extent at presence nitrogen oxides. results highlight importance particle water content for molecular compounds.
Language: Английский
Citations
0