Inter-comparison of oxidative potential metrics for airborne particles identifies differences between acellular chemical assays

Atmospheric aging modifies the redox potential and toxicity of humic-like substances (HULIS) from biomass burning

“…Based on the TOC results, the initial solutions were diluted with deionized water, phosphate-buffered saline (PBS) solution, and surrogate lung fluid (SLF) at consistent HULIS concentration of 25 mg OC L −1 , which is relevant to environmental exposure and also provides a stock solution that keeps consistency among different experiments. 47 The PBS solution was treated with Chelex 100 sodium resin and had a pH of 7.4. The SLF solution was prepared with additional antioxidants (200 μM l -ascorbic acid sodium salt, 300 μM citric acid, 100 μM reduced l -glutathione, and 100 μM uric acid sodium salt) in the PBS solution.…”

Cross-cutting research and future directions under the GAPS networks

“…47,48 Prominent chemicals that contribute to OP are transition metals (in particular Cu and Fe) and quinones; however, other species such as peroxides, secondary organic matter, and oxidation products of tire-wear chemicals, among others, could contribute to OP. 26,45,[49][50][51][52][53] Research to this date has focused on characterization of OP from particulate matter collected using active sampling technique. While metals are found primarily in particulate matter, semi-volatile organic species such as quinones are distributed in both gas and particulate phase in ambient air.…”

Is the oxidative potential of components of fine particulate matter surface-mediated?

“…The H 2 O 2 assay presents the physiological conditions best, since it includes the endogenous antioxidant in physiologically relevant concentrations in a simulated ELF measuring a product, which is also produced in the human body. Acellular OP assays including these have recently been intercompared (Shahpoury et al 2022). Samples from the QF and the mist chamber were blank controlled (producing daily minimum of one ELF and one QF blank, which remained unloaded but otherwise followed the exact same lab treatment and handling as the loaded ELF and QF samples, respectively).…”