A methodology for modeling the formation and decay of nitro-PAH in the atmosphere

Sorbent-coated diffusion denuders for direct measurement of gas/particle partitioning by semi-volatile organic compounds

“…Their earlier work had suggested that sampling artifacts compromised the results based on filter-sorbent sampling [ 171. Using the IOVPS they found the nitro-PAH photochemical products of pyrene and fluoranthene entirely in the particulate phase [17,18], in contrast to earlier work that suggested the products were distributed between the phases. They concluded that formation of nitro-PAH in the gas phase from OH and NO:!…”

“…Two denuder sections were used upstream of the filter pack, and a third denuder downstream collected any PAH that desorbed from the particles during sampling. To increase capacity, multi-channel versions of the IOVPS have been used by other investigators [17][18][19][20][21][22][23][24][25][26][27], in 24 and 40 cm lengths.…”

“…Compared to the IOVPS, the denuders in these samplers have roughly twice the outer diameter and three times the active length of the single-channel IOVPS used at LBNL [14,15]. Their coated area is about thirty times more than a single-channel IOVPS [ 14,151 and about four times the area of the long multi-channel IOVPS [17][18][19][20][21][22][23][24][25][26][27].…”

“…The denuder coating was intentionally removed after solubilization of the species of interest. The Kamens group and others [17][18][19][20][21][22][23][24][25][26][27] have used solvent mixtures such as hexane, acetone and dichloromethane to extract PAH, nitro-PAH, dioxins and a variety of semivolatile combustion-generated organics from the XAD-coated surfaces of the IOVPS. They have also shown that coated denuders can be reused at least 20 times before recoating, as long as extraction blanks are monitored regularly [ 17,181.…”

“…Fan, et al incorporated the IOVPS for sampling semi-volatile PAH and nitro-PAH as part of the Kamens group's ongoing atmospheric chemistry research program [17][18][19][20][21][22][23][24]261. They have made important contributions to validation of the IOVPS, as mentioned above, and they have used it extensively to enhance understanding of gadparticle partitioning and the atmospheric chemistry of PAH, nitro-PAH and dioxins.…”