Formaldehyde and glyoxal measurement deploying a selected ion flow tube mass spectrometer (SIFT-MS)

Abstract

Abstract. Formaldehyde (FM) and glyoxal (GL) are important atmospheric species of indoor and outdoor environments. They are either directly emitted in the atmosphere, or they are formed through the oxidation of organic compounds by indoor and/or outdoor atmospheric oxidants. Despite their importance, the real-time monitoring of these compounds with soft ionization mass spectrometric techniques, e.g., proton transfer mass spectrometry (PTR-MS), remains problematic and is accompanied by low sensitivity. In this study, we evaluate the performance of a multi-ion selected ion flow tube mass spectrometer (SIFT-MS) to monitor in real-time atmospherically relevant concentrations of FM and GL under controlled experimental conditions. The SIFT-MS used is operated under standard conditions (SCs), as proposed by the supplier, and custom conditions (CCs) to achieve higher sensitivity. In the case of FM, SIFT-MS sensitivity is marginally impacted by relative humidity (RH), and the detection limits achieved are below 200 ppt (parts per trillion). Contrariwise, in the case of GL, a sharp decrease of instrument sensitivity is observed with increasing RH when the H3O+ ion is used. Nevertheless, the detection of GL, using NO+ precursor ion, is moderately impacted by moisture with an actual positive sensitivity response. Therefore, we recommend the use of the NO+ precursor for the reliable detection and quantitation of GL. This work evidences that SIFT-MS can be considered as an efficient tool to monitor the concentration of FM and GL in laboratory experiments, and potentially in indoor or outdoor environments, capable of identifying their primary emission or secondary formation through (photo)oxidation processes. Furthermore, SIFT-MS technology still allows great possibilities for sensitivity improvement and high potential for monitoring low proton transfer affinity compounds.

Unraveling the Uptake of Glyoxal on a Diversity of Natural Dusts and Surrogates: Linking Dust Composition to Glyoxal Uptake and Estimation of Atmospheric Lifetimes

“…The monomer of pure Gly was synthesized by mixing equal amounts of Gly trimer dihydrate (purity ≥97% Sigma-Aldrich) and diphosphorus pentoxide (purity >98%, VWR Chemicals) in a glass bulb that was progressively heated from room temperature to 453 K, under vacuum (1.5 × 10 –3 Torr). Details about the synthesis, purification process, and characterization of Gly are presented elsewhere . Finally, the vapors of pure Gly monomer (>99%) were collected in a 4 L glass bulb, reaching a total pressure of 7 to 10 Torr.…”

“…Details about the synthesis, purification process, and characterization of Gly are presented elsewhere. 48 Finally, the vapors of pure Gly monomer (>99%) were collected in a 4 L glass bulb, reaching a total pressure of 7 to 10 Torr. In all experiments, pure gas-phase Gly was used.…”

Rate coefficients for the gas‐phase OH + furan (C4H4O) reaction between 273 and 353 K

“…The reaction progress was monitored continuously via SIFT-MS (Voice 200 ultra, ∼0.2 Hz sampling rate in most measurements) and FTIR (Antaris, Thermo). 19 C 4 H 4 O loss was monitored relative to that of a selected reference compound. The concept in the RR method is that the reactant and a reference compound are lost solely via their reaction with the reactive species of interest, that is, the OH radical.…”

“…Once reactants were well mixed, as verified via infrared and mass spectral signals, the UV‐C lamps, maximum output at 254 nm, were turned on and the H 2 O 2 photolysis led to OH radical formation, initiating the reaction. The reaction progress was monitored continuously via SIFT‐MS (Voice 200 ultra, ∼0.2 Hz sampling rate in most measurements) and FTIR (Antaris, Thermo) 19 …”