Istituto di Scienze e Tecnologie per L'Energia e La Mobilità Sostenibili, STEMS-CNR, P.le Tecchio 80, 80125, Napoli, Italy.
Istituto di Scienze e Tecnologie per L'Energia e La Mobilità Sostenibili, STEMS-CNR, P.le Tecchio 80, 80125, Napoli, Italy.
Chemosphere. 2021 Aug;276:130174. doi: 10.1016/j.chemosphere.2021.130174. Epub 2021 Mar 10.
Volatile organic compounds (VOC) and polycyclic aromatic hydrocarbons (PAH), emitted in the environment from a wide range of combustion sources, are hazardous to human health and considered important precursors of both primary and secondary particulate pollutants. In the present work, light hydrocarbons up to C, as main components of combustion-derived VOC, and PAH produced in fuel-rich conditions of premixed ethylene flames were analyzed by implementing a molecular-beam time of flight mass spectrometer (MB-TOFMS), purposely built for on-line fast monitoring of the environmental impact of combustion systems. The reliability of the MB-TOFMS was preliminarily verified on a slightly-sooting flame, comparing the results with those obtained by batch sampling and gas chromatographic techniques. Electron ionization (EI) and multi-photon ionization (MPI) were used as MB-TOFMS sources and tested on combustion gases of a no-sooting premixed ethylene flame where VOC and PAH are present in traces not detectable with batch sampling and conventional analytical techniques. The mass identification accuracy was improved and guaranteed by systematically performing internal mass calibration, exploiting the formation of "in situ" clusters from combustion water in the molecular beam apparatus. Selective and sensitive monitoring of light hydrocarbons and PAH, derived from oxidation and pyrolysis reactions featuring combustion, was shown to be especially effective when using the MB-TOFMS equipped with MPI source. This technique showed to be effective also for the detection of radical species that are important for the risk assessment of aerosol and fundamental understanding of aerosol chemistry at a molecular level.
挥发性有机化合物（VOC）和多环芳烃（PAH），从广泛的燃烧源排放到环境中，对人类健康有害，被认为是原生和次生颗粒物污染物的重要前体。在本工作中，采用分子束飞行时间质谱仪（MB-TOFMS）对燃烧衍生 VOC 的主要成分轻烃和富燃料条件下预混乙烯火焰中生成的 PAH 进行了分析，该仪器专门用于在线快速监测燃烧系统对环境的影响。MB-TOFMS 的可靠性在一个轻微冒烟的火焰上进行了初步验证，将结果与分批采样和气相色谱技术获得的结果进行了比较。电子电离（EI）和多光子电离（MPI）被用作 MB-TOFMS 的源，并在无烟尘预混乙烯火焰的燃烧气体上进行了测试，其中 VOC 和 PAH 以痕量存在，用分批采样和常规分析技术无法检测到。通过在分子束装置中从燃烧水中形成“原位”团簇，系统地进行内部质量校准，提高并保证了质量识别的准确性。当使用配备 MPI 源的 MB-TOFMS 时，对燃烧过程中氧化和热解反应产生的轻烃和 PAH 的选择性和敏感监测显示出特别有效。该技术对于检测对气溶胶风险评估和气溶胶化学在分子水平上的基本理解很重要的自由基也很有效。
