Surdu Mihnea, Pospisilova Veronika, Xiao Mao, Wang Mingyi, Mentler Bernhard, Simon Mario, Stolzenburg Dominik, Hoyle Christopher R, Bell David M, Lee Chuan Ping, Lamkaddam Houssni, Lopez-Hilfiker Felipe, Ahonen Lauri R, Amorim Antonio, Baccarini Andrea, Chen Dexian, Dada Lubna, Duplissy Jonathan, Finkenzeller Henning, He Xu-Cheng, Hofbauer Victoria, Kim Changhyuk, Kürten Andreas, Kvashnin Aleksandr, Lehtipalo Katrianne, Makhmutov Vladimir, Molteni Ugo, Nie Wei, Onnela Antti, Petäjä Tuukka, Quéléver Lauriane L J, Tauber Christian, Tomé António, Wagner Robert, Yan Chao, Prevot Andre S H, Dommen Josef, Donahue Neil M, Hansel Armin, Curtius Joachim, Winkler Paul M, Kulmala Markku, Volkamer Rainer, Flagan Richard C, Kirkby Jasper, Worsnop Douglas R, Slowik Jay G, Wang Dongyu S, Baltensperger Urs, El Haddad Imad
Laboratory of Atmospheric Chemistry, Paul Scherrer Institute 5232 Villigen Switzerland
Center for Atmospheric Particle Studies, Carnegie Mellon University 15213 Pittsburgh PA USA.
Environ Sci Atmos. 2021 Aug 23;1(6):434-448. doi: 10.1039/d1ea00050k. eCollection 2021 Sep 23.
Aerosol particles negatively affect human health while also having climatic relevance due to, for example, their ability to act as cloud condensation nuclei. Ultrafine particles (diameter < 100 nm) typically comprise the largest fraction of the total number concentration, however, their chemical characterization is difficult because of their low mass. Using an extractive electrospray time-of-flight mass spectrometer (EESI-TOF), we characterize the molecular composition of freshly nucleated particles from naphthalene and β-caryophyllene oxidation products at the CLOUD chamber at CERN. We perform a detailed intercomparison of the organic aerosol chemical composition measured by the EESI-TOF and an iodide adduct chemical ionization mass spectrometer equipped with a filter inlet for gases and aerosols (FIGAERO-I-CIMS). We also use an aerosol growth model based on the condensation of organic vapors to show that the chemical composition measured by the EESI-TOF is consistent with the expected condensed oxidation products. This agreement could be further improved by constraining the EESI-TOF compound-specific sensitivity or considering condensed-phase processes. Our results show that the EESI-TOF can obtain the chemical composition of particles as small as 20 nm in diameter with mass loadings as low as hundreds of ng m in real time. This was until now difficult to achieve, as other online instruments are often limited by size cutoffs, ionization/thermal fragmentation and/or semi-continuous sampling. Using real-time simultaneous gas- and particle-phase data, we discuss the condensation of naphthalene oxidation products on a molecular level.
气溶胶颗粒对人类健康有负面影响，同时由于它们能够作为云凝结核等原因而与气候相关。超细颗粒（直径<100纳米）通常在总数浓度中占最大比例，然而，由于其质量低，对其进行化学表征很困难。我们使用萃取电喷雾飞行时间质谱仪（EESI-TOF），在欧洲核子研究中心的CLOUD室中对萘和β-石竹烯氧化产物新生成颗粒的分子组成进行了表征。我们对EESI-TOF和配备了气体和气溶胶过滤入口的碘化物加成化学电离质谱仪（FIGAERO-I-CIMS）测量的有机气溶胶化学成分进行了详细的比对。我们还使用了基于有机蒸汽冷凝的气溶胶生长模型，以表明EESI-TOF测量的化学成分与预期的冷凝氧化产物一致。通过限制EESI-TOF化合物特异性灵敏度或考虑凝聚相过程，这种一致性可以得到进一步改善。我们的结果表明，EESI-TOF能够实时获取直径小至20纳米、质量负荷低至数百纳克/立方米的颗粒的化学成分。到目前为止，这很难实现，因为其他在线仪器往往受到尺寸截断、电离/热裂解和/或半连续采样的限制。利用实时同步的气相和颗粒相数据，我们在分子水平上讨论了萘氧化产物的冷凝过程。
