Chemical composition, structures, and light absorption of N-containing aromatic compounds emitted from burning wood and charcoal in household cookstoves

N-containing aromatic compounds (NACs) are an important group of light-absorbing molecules in the atmosphere. They are often observed in combustion emissions, but their chemical formulas and structural characteristics remain uncertain. In this study, red oak wood and charcoal fuels were burned in cookstoves using the standard water boiling test (WBT) procedure. Submicron aerosol particles in the cookstove emissions were collected using quartz (Qf) and polytetrafluoroethylene (PTFE) filter membranes positioned in parallel. A back-up quartz filter (Qb) was also installed downstream of the PTFE filter to evaluate the effect of sampling artifact on NACs measurements. Liquid chromatography-mass spectroscopy (LC-MS) techniques identified seventeen NAC chemical formulas in the cookstove emissions. The average concentrations of total NACs in Qb samples (0.37 ± 0.31–1.78 ± 0.78 µg m−3) were greater than 50 % of those observed in the Qf samples (0.47 ± 0.40–3.54 ± 1.63 µg m−3), and the Qb to Qf mass ratios of individual NACs had a range of 0.02–2.71, indicating that the identified NACs might have substantial fractions remaining in the gas-phase. In comparison to other sources, cookstove emissions from red oak or charcoal fuels did not exhibit unique NAC structural features, but had distinct NACs composition. However, before identifying NACs sources by combining their structural and compositional information, the gas-particle partitioning behaviors of NACs should be further investigated. The average contributions of total NACs to the light absorption of organic matter at λ = 365 nm (1.10–2.58 %) in Qf samples are much lower than those in Qb samples (10.7–21.0 %). These results suggest that more research is needed to understand the chemical and optical properties of gaseous chromophores and heavier molecular weight (e.g., MW > 500 Da) entities in particulate matter.