真空紫外光电离质谱法在烟气老化研究中的应用

马兰; 温作赢; 彭晓萌; 赵锋; 叶绍鑫; 谢恺; 顾学军; 王健

doi:10.7538/zpxb.2024.0023

中国科学院合肥物质科学研究院安徽光学精密机械研究所，安徽合肥　230031

中国科学技术大学，安徽合肥　230026

安徽中烟工业有限责任公司，烟草化学安徽省重点实验室，安徽合肥　230088

通讯作者: 顾学军; 王健

中图分类号: O657.63

Application of Vacuum Ultraviolet Photoionization Mass Spectrometry in the Aging Study of Smoke Aerosols

Anhui Institute of Optics & Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China

University of Science and Technology of China, Hefei 230026, China

Key Laboratory of Combustion and Pyrolysis, China Tobacco Anhui Industrial Co, Ltd, Hefei 230088, China

Corresponding authors: Xue-jun GU ; Jian WANG

MSC: O657.63

摘要: 本文应用自主研发的真空紫外光电离飞行时间质谱仪，原位在线检测燃烧型卷烟、加热不燃烧型卷烟和电子烟产生的烟气气溶胶，表征其气相成分及颗粒相成分。结果表明，3种烟气气溶胶的化学组成差异显著，其中燃烧型卷烟的成分含量及物种丰度远大于新型烟草制品，其气相和颗粒相的整体信号强度分别约为新型烟草制品的100倍和10倍。检出的气溶胶成分中含有大量不饱和化合物，这些物质在环境中极易被氧化并生成新的超细颗粒物。结合Teflon反应腔分别模拟以上3种类型的烟气气溶胶在不同臭氧浓度下的老化过程，结果均有超细颗粒物生成。超细颗粒物的形成条件与前体物的含量和成分分布有关，燃烧型卷烟气溶胶在室内O₃浓度下就可以很快形成超细颗粒物，而新型烟草制品则需要更高浓度的O₃或更长的老化时间。

关键词:

Abstract: Smoke aerosols contain many harmful substances and have become one of the major sources of indoor pollutants. The smoke aerosols released into the environment are easy to react with various oxidants presented in the room, namely the aging process of the smoke aerosol, which can produce secondary organic aerosols. The chemical composition of smoke aerosol is an important factor affecting its indoor aging process, but so far, the change behavior of the composition and particle size distribution of smoke aerosol during the aging process remains to be studied, and the aging analysis of novel tobacco products has not been reported. Therefore, the present study applied a house-made vacuum ultraviolet photoionization time-of-flight mass spectrometer to detect the chemical composition of the smoke aerosols produced by combustion cigarette, and new tobacco products, e.g., heat-not-burn tobacco products and e-cigarette, achieving the in-situ online characterization of their gas-phase and particulate-phase components. The results showed that the chemical composition of the smoke aerosols generated by the three types of tobacco products is significantly different, among which the component content and species abundance of the combustion cigarette are much greater than those of the novel tobacco products, and the overall signal intensity of combustion cigarette in the gas-phase and the particulate-phase is about 100 times and 10 times that of novel tobacco products, respectively. In addition, it was found that the particulate-phase mass spectra of novel tobacco products contain a large amount of glycerol, which is almost absent in combustion cigarette, and its intensity is even more than nicotine. The detected aerosol components contain many unsaturated compounds, which are easily oxidized in the environment and generate new ultrafine particles (UFPs). The Teflon chamber was used to simulate the aging process of the above three smoke aerosols with different O₃ concentrations. The results of scanning mobility particle sizer showed that UFPs are generated in all of them. Corresponding to the results of photoionization mass spectrometry, the aging processes of the three smoke aerosols are completely different, in which the formation conditions of UFPs are related to the content and composition distribution of precursors. Specifically, the indoor concentration of O₃ (observed in this experiment was 40 μg/m³) can promote the formation of UFPs with a geometric mean diameter of about 26 nm in the combustion cigarette, while the UFPs formation of novel tobacco products requires a higher concentration of O₃ or a longer aging time. This is mainly facts that the whole composition concentration of the novel tobacco products is much lower than that of combustion cigarette, and the particulate-phase components contain a lot of glycerol. Due to the strong viscosity and encapsulation, glycerol may exist in the particulate-phase of the smoke aerosol in the form of coating other substances, such as nicotine, and further prevents the aging process of other substances, resulting in differences in particle size distribution. This study explains the reason of difference in UFPs formation of various smoke aerosols during the aging process and provides a basis for tobacco exposure risk assessment, which is expected to reveal the aging mechanism of smoke aerosols in the future.

Key words:

真空紫外光电离质谱法在烟气老化研究中的应用

通讯作者: 顾学军;

通讯作者: 王健

1. 中国科学院合肥物质科学研究院安徽光学精密机械研究所，安徽合肥　230031

2. 中国科学技术大学，安徽合肥　230026

3. 安徽中烟工业有限责任公司，烟草化学安徽省重点实验室，安徽合肥　230088

收稿日期: 2024-03-18

录用日期: 2024-07-15

关键词:

Application of Vacuum Ultraviolet Photoionization Mass Spectrometry in the Aging Study of Smoke Aerosols

Corresponding author: Xue-jun GU ;

Corresponding authors: Jian WANG

1. 中国科学院合肥物质科学研究院安徽光学精密机械研究所，安徽合肥　230031

2. 中国科学技术大学，安徽合肥　230026

3. 安徽中烟工业有限责任公司，烟草化学安徽省重点实验室，安徽合肥　230088

Received Date: 2024-03-18

Accepted Date: 2024-07-15

Keywords:

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烟气气溶胶含有多种有毒有害成分^[1]，对人体健康危害较大，是室内污染物的主要来源之一^[2]。近年来，出现了一系列新型烟草制品，如加热不燃烧型卷烟和电子烟。相比于传统的燃烧型卷烟，新型烟草制品不需要经过高温燃烧便可传递尼古丁，且在设计上避免了侧流烟气的产生，有效减少了有害和潜在有害物质的形成量和暴露量^[3-5]。但研究表明^[6-9]，这些新型烟草制品在使用过程中仍会不断释放有毒物质，直接影响室内环境质量和人体健康。

释放到环境中的烟气气溶胶会与室内存在的各类氧化剂作用^[10-12]，经历烟气的老化过程，形成二次有机气溶胶，并生成毒性更大的氧化产物^[13-14]。有研究表明^[13,15]，燃烧型卷烟气溶胶在室内O₃的诱导下可产生新的超细颗粒物（粒径小于100 nm）。烟气气溶胶的化学成分是影响其室内老化过程的重要因素，目前，关于烟气气溶胶的成分及粒径分布在其老化过程中的变化行为还有待研究，而对于新型烟草制品的老化分析还尚未见报道。采用多种分析手段对不同种类烟气气溶胶的化学成分进行准确检测与表征，并分析其与老化过程中粒径分布的关系，已成为烟草暴露风险评估的重要基础。

针对烟气气溶胶的成分检测，传统方法主要为基于色谱与质谱联用的离线检测技术，如气相色谱-质谱和液相色谱-质谱等^[16-18]。这些方法通常需要经历样品的离线富集及预处理过程，检测条件（如时间、温度等）会影响烟气气溶胶的化学成分在气相和颗粒相中的分布^[19]，因此较难获得新鲜烟气气溶胶的化学成分信息。近些年，傅里叶变换红外光谱（FTIR）^[20]、红外激光光谱^[21]以及基于激光共振增强多光子电离（REMPI）或真空紫外灯单光子电离的光电离质谱（PIMS）^[22-24]等方法被广泛应用于表征烟气气溶胶的气相成分。但由于烟气气溶胶中的颗粒相成分较复杂，能够直接对其进行原位检测的技术较少。Barsanti等^[25]将核磁共振波谱（NMR）技术应用于卷烟颗粒物的原位化学分析，但获得的成分信息有限，且谱图分析复杂。其他检测方法，如基于激光电离的气溶胶飞行时间质谱^[26]、实时直接分析质谱（DART-MS）^[27]及化学电离质谱（CIMS）^[28]等也被应用于烟气颗粒物的成分检测，但这些研究多关注于颗粒物收集、稀释及汽化等技术的创新，未能获得全面的成分信息。

基于此，本工作拟应用自主研发的真空紫外光电离飞行时间质谱（VUV-TOF MS）仪对传统的燃烧型卷烟以及加热不燃烧型卷烟和电子烟2种新型烟草制品的化学成分进行对比研究，通过吸烟机与光电离质谱仪的毛细管进样口或空气动力学透镜进样系统直接相连，实现各类烟气气溶胶气相成分和颗粒相成分的原位在线检测。同时，采用Teflon反应腔模拟3种烟气气溶胶在不同O₃浓度下的室内老化过程，并利用扫描电迁移率粒径谱仪实时监测老化过程中的粒径迁移及粒子数浓度，尤其关注老化过程中超细颗粒物的生成情况。最后，结合光电离质谱获得的成分信息对不同类型烟气气溶胶老化过程中的粒谱进行分析。

3. 结论

本文基于自制的真空紫外光电离飞行时间质谱仪，原位在线检测了燃烧型卷烟、加热不燃烧型卷烟和电子烟烟气气溶胶的气相成分与颗粒相成分。采用Teflon反应腔模拟以上3种类型烟气气溶胶在不同臭氧浓度下的老化过程，并利用扫描电迁移率粒径谱仪表征它们在室内老化过程中的粒径分布。光电离质谱结果表明，3种烟气气溶胶的化学成分分布不同，燃烧型卷烟的成分含量及物种丰度要远大于新型烟草制品，其气相和颗粒相信号强度分别约为新型烟草制品的100倍和10倍。此外，在烟气颗粒相的光电离质谱检测中发现，新型烟草制品中含有大量几乎不存在于燃烧型卷烟中的甘油，其信号强度甚至超过尼古丁。3种烟气气溶胶的室内老化过程不同，超细颗粒物的形成条件与前体物的含量和成分分布有关。具体表现为，室内浓度的O₃（本实验中室内O₃最低浓度为40 μg/m³）就可以促使燃烧型卷烟烟气气溶胶生成新的几何平均直径约为26 nm的超细颗粒物，而新型烟草制品由于整体的化学成分浓度远小于燃烧型卷烟，且颗粒相中含有的大量甘油阻止了其老化进程，因而只有在更高浓度的O₃或更长的老化时间下才能够形成超细颗粒物。

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