Methodological advances to improve repeatability of SOA generation in environmental chambers

Nontrivial Impact of Relative Humidity on Organic New Particle Formation from Ozonolysis of cis-3-Hexenyl Acetate

“…Owing to the difficulty in reproducing an exact RH Air 2023, 1 226 at such low levels, all experiments with any humidity present were performed only once. Nonetheless, we have demonstrated in a previous report [43] that the typical reproducibility utilizing our optimized setup is better than 10% relative standard deviation. Table 1.…”

“…n = 3 for the dry experiment at 0.0% RH, and n = 1 for all other runs. Typical relative standard deviation for each metric is less than 10%, as demonstrated in a separate report [43].…”

“…C SOA values obtained from SMPS measurements have been corrected for wall losses using ammonium sulfate reference aerosol in accordance with a previously established method [42]. Standard deviations are estimated based on a previous report that systematically evaluated instrumental errors in our chamber measurements [43]. In accord with this previously established method [43], ξ O3 was established in the chamber prior to injection of the VOC, which helped minimize variability in the measurements.…”

“…Standard deviations are estimated based on a previous report that systematically evaluated instrumental errors in our chamber measurements [43]. In accord with this previously established method [43], ξ O3 was established in the chamber prior to injection of the VOC, which helped minimize variability in the measurements. It may be that the order in which the reagents are injected will impact the outcomes; however, this is beyond the scope of the present study.…”

“…• C. Once the RH and ξ O3 were established and equilibrated in the chamber (10-15 min after O 3 injection), a glass micro-syringe (Hamilton 7000 series gas-tight syringe) was used to quantitatively transfer VOC aliquots to a glass three-neck flask that was placed in a hot water bath (80 ± 2 • C). For the ternary system experiments, a split valve and stop/flow valve were used on the injection line with a 2 L min −1 flow of zero air to the UVMEC to permit particle measurements at low ξ VOC (detailed here: [43]). For the quaternary system experiments, a solution mixture of CHA and α-pinene was prepared (dissolving α-pinene directly into CHA) to the desired mole ratio, permitting both VOCs to be injected as a single aliquot.…”