Accurate identification of dimers from α‐pinene oxidation using high‐resolution collision‐induced dissociation mass spectrometry

Abstract

Interest in mass spectrometry of highly oxidized dimers from α-pinene oxidation has increased in the atmospheric chemistry field. Here, we apply high-resolution collision-induced dissociation mass spectrometry (HR-CID-MS) with an atmospheric pressure ionization source to investigate in detail how α-pinene-derived dimers are detected and identified by MS. The resulting HR-CID spectra and specific fragmentation patterns suggest that a large fraction of dimer ions detected in full-scan mass spectra can be hydrogen-bonded artifact clusters and the residual small fraction includes covalently bonded actual dimers. We also show how individual fractions of the artifact clusters and actual dimers are calculated using the HR-CID spectra. K E Y W O R D Sα-pinene, dimer, high-resolution collision-induced dissociation mass spectrometry, hydrogenbonded artifact cluster, oxidation

Isomer-Resolved Reactivity of Organic Peroxides in Monoterpene-Derived Secondary Organic Aerosol

“…The development of mass spectrometry (MS) enables characterization of specific organic compounds in SOA . Recently, different MS techniques have been successfully applied in the detection of molecular composition of particle-phase organic peroxides ,− and HOMs. ,, A few studies have attempted to quantify the particle-phase or bulk aqueous-phase reactivity of specific organic peroxides, such as monoperoxypinic acids, α-acyloxyalkyl hydroperoxides (α-AAHPs), and α-hydroxyalkyl hydroperoxides (α-HHs) ,− relevant to monoterpene SOA, at a molecular level using synthesized authentic standards with MS measurements. It was found that monoperoxypinic acids in SOA degraded with a lifetime of several hours at room temperature, while α-AAHPs and α-HHs could undergo aqueous-phase hydrolysis on timescales of several minutes to hours, depending on the molecular structure, water content, acidity, and temperature. ,,− A few other studies have focused on the particle-phase reactivity of individual HOMs. , For example, Mutzel et al found that a set of carbonyl-containing HOMs arising from α-pinene ozonolysis can decompose to form C 1 –C 4 carbonyls in the particle phase via the Korcek mechanism.…”

Temperature and acidity dependence of secondary organic aerosol formation from <i>α</i>-pinene ozonolysis with a compact chamber system

“…The latter assignment of the product also has a hydroperoxide group. The formation of hydroperoxides involving Criegee intermediates has been observed in the gas phase (Sekimoto et al, 2020) and on the surface of aqueous droplets (Enami and Colussi, 2017). The relatively high intensity of m/z 355 under acidic seed conditions might be explained by the fact that the hydrolysis of ester hydroperoxides becomes slower under acidic conditions (Zhao et al, 2018).…”

“…Zhang et al (2017) as hydroperoxides from α-pinene ozonolysis reactions. They can decompose under acidic seed conditions to m/z 197.081 (C 10 H 13 O 4 , VBS bin 2) (Scheme 1a) as well as m/z 155.010 (C 8 H 11 O 3 , VBS bin 5) (Scheme 1b) (acid-catalyzed decomposition of hydroperoxides; Seubold and Vaughan, 1953). Next, previous studies indicate that m/z 171 and 185 were monomer precursors of dimers m/z 343 and 357, and all four products exist in both laboratory α-pinene ozonolysis SOA samples and field samples (Gao et al, 2004;Yasmeen et al, 2010;Kristensen et al, 2014;Zhang et al, 2015).…”

Carbon-Supported Nickel Catalysts—Comparison in Alpha-Pinene Oxidation Activity

“…The increase in the values of alpha-pinene conversion with a simultaneous decrease in the selectivity of the alpha-pinene oxide values indicates that the oxidation of alpha-pinene is replaced by the reactions in which alpha-pinene oxide undergoes other transformations (isomerization, dimerization, and polymerization). The main oxidation products of alphapinene and the exemplary products of follow-up reactions are shown in Figure 11 [63]. Figure 12 shows the catalytic activity of the catalysts obtained by the hydrothermal method under the conditions of the preliminary tests.…”