University of Washington, Mechanical Engineering, Seattle, Washington 98195, United States.
University of Washington, Chemical Engineering, Seattle, Washington 98195, United States.
Environ Sci Technol. 2020 Jul 7;54(13):8198-8209. doi: 10.1021/acs.est.0c01110. Epub 2020 Jun 12.
Analysis of particulate matter (PM) is important for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM. Specifically, polycyclic aromatic hydrocarbons (PAHs) found in ultrafine PM have been linked to cardiovascular diseases and carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with lower molecular weight (LMW, 126 < MW < 202) and higher molecular weight (HMW, 226 < MW < 302), i.e., smaller and larger than Pyrene, in combustion-generated PM using excitation-emission matrix (EEM) fluorescence spectroscopy. Laboratory combustion PM samples were generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on ethylene and ethane. Fuel dilution by Ar in 0% to 90% range controlled the flame temperature. The colder flames result in lower PM yields however, the PM PAH content increases significantly. Temperature thresholds for PM transition from low to high organic carbon content were characterized based on the maximum flame temperature ( ∼ 1791 to 1857 K) and the highest soot luminosity region temperature ( ∼ 1600 to 1650K). Principal component regression (PCR) analysis of the EEM spectra of IGFR samples correlates to GCMS data with R = 0.988 for LMW and 0.998 for HMW PAHs. PCR-EEM analysis trained on the IGFR samples was applied to PM samples from woodsmoke and diesel exhaust, the model accurately predicts HMW PAH concentrations with R = 0.976 and overestimates LMW PAHs.
分析颗粒物（PM）对于评估人类暴露于潜在有害剂，特别是燃烧生成的 PM 非常重要。具体而言，在超细 PM 中发现的多环芳烃（PAHs）与心血管疾病以及致癌和致突变作用有关。在这项研究中，我们使用激发发射矩阵（EEM）荧光光谱法定量了燃烧生成的 PM 中具有较低分子量（LMW，126<MW<202）和较高分子量（HMW，226<MW<302）的 PAHs 的存在和浓度，即比焦 烯更小和更大的 PAHs。实验室燃烧 PM 样品在层流扩散倒置重力火焰反应器（IGFR）中使用乙烯和乙烷生成。Ar 在 0%至 90%范围内的燃料稀释控制火焰温度。较冷的火焰导致 PM 产率降低，但是 PM 中 PAH 含量显著增加。基于最大火焰温度（1791 至 1857 K）和最高烟尘发光区温度（1600 至 1650 K），对 PM 从低有机碳含量向高有机碳含量转变的温度阈值进行了表征。对 IGFR 样品的 EEM 光谱进行主成分回归（PCR）分析，与 GCMS 数据相关，LMW 和 HMW PAHs 的 R 值分别为 0.988 和 0.998。基于 IGFR 样品训练的 PCR-EEM 分析应用于木烟和柴油尾气的 PM 样品，该模型能够准确预测 HMW PAH 浓度，R 值为 0.976，并且高估了 LMW PAH。
