Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) for aircraft and ground-based applications

适用于飞机和地面应用的质子转移反应飞行时间质谱仪 (PTR-ToF-MS)

• 批准号: NE/T009020/1
• 负责人: David Oram
• 金额: $ 38.23万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT009020%2F1
• 关键词: Proton; Transfer; Reaction; Time; Flight

Volatile organic compounds (VOCs) are trace gases that play an important role in many atmospheric and biogeochemical processes. They are a major component of air pollution, being emitted directly to the atmosphere by natural and anthropogenic sources, e.g. transport, industrial processes, biomass burning, solvent use, etc., and also formed as secondary products by chemical reactions in the atmosphere. VOCs contribute to the formation of ozone and particulate matter in the lower atmosphere. Ozone is a respiratory irritant, a greenhouse gas and can decrease crop yields, leading to substantial economic losses. Fine particulate matter, such as PM2.5 (particles less than 2.5 um in diameter), is linked to numerous human health conditions (e.g. asthma, heart disease) and affects the radiation balance at the Earth's surface (links to climate). VOCs also play a key role in determining the oxidising capacity of the atmosphere (the Earth's ability to cleanse pollutants from the atmosphere), and it is becoming increasingly apparent that VOCs contribute significantly to indoor air pollution. In polar regions, biological and photochemical production of VOCs occurs at the snow-ice interface and in the surface ocean. However, the biogeochemical cycles of VOC formation in Arctic atmosphere remain poorly described, with unknown feedback responses to Arctic sea ice decline. As our understanding of atmospheric processes increases and computer models become more sophisticated, there is a requirement for ever-better measurements, in terms of analytical sensitivity (measuring smaller amounts), chemical speciation (identifying and measuring a larger range of compounds) and speed (faster response times to enable us to study, e.g., from a moving aircraft or to measure fast fluxes). This will help us to understand the fundamentals which are controlling these often-complex atmospheric interactions. For VOC measurements the Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) will be of great benefit in this respect and will be deployable across a broad range of measurement platforms (aircraft, lab/chamber studies, observatories) and topical research areas (global atmospheric composition, indoor/outdoor air quality, mechanistic studies, fluxes).The PTR-QMS currently used on the FAAM aircraft was bought 17 years ago. It is based on a quadrupole detection system which limits the capability of the powerful PTR technique. These deficiencies include low mass resolution (inability to resolve compounds of equal mass), the necessity to pre-select a limited number of compounds (typically ~10), low sensitivity, particularly at higher masses (>100 Da). We therefore propose to replace the current PTRMS with a state-of-the-art PTR-ToF instrument which will help keep the FAAM aircraft at the cutting edge of global atmospheric research. Advantages of the PTR-ToF include: (1) Large increase in the number of compounds measured (ToF records all masses over a wide mass range, whereas the quadrupole only records a small number of pre-selected compounds); (2) Improved mass range (1-1000 Da) without loss of sensitivity at masses >100 Da; (3) Improved sensitivity (lower limit of detection); (4) Higher mass resolution (e.g. quadrupole cannot distinguish between isoprene (mass 68.117), an important biogenic compound, and furan (mass 68.075), a product of biomass burning; (5) Faster scanning; (6) Selective reagent ionisation (the use of different ion source reagents allows for improved specificity of the instrument, e.g. separation of aldehydes and ketones).The deployment of the PTR-ToF-MS in the unique RVG-Air-Sea-Ice chamber will allow the study of VOC production processes in a controlled environment, enhancing our understanding of the key parameters of VOC cycles in sea ice areas. Beyond the RvG-ASIC, the PTR-ToF-MS will open new avenues for field campaigns in polar seas, e.g. the impact of increasing shipping activity on air quality in the Arctic.

挥发性有机化合物（VOCs）是一种在大气和地球化学过程中起重要作用的痕量气体。它们是空气污染的主要组成部分，通过自然和人为来源，例如运输、工业加工、生物质燃烧、溶剂使用等，直接排放到大气中，并且还通过大气中的化学反应作为次级产物形成。挥发性有机化合物有助于在低层大气中形成臭氧和颗粒物。臭氧是一种呼吸道刺激物，一种温室气体，可降低作物产量，导致重大经济损失。细颗粒物，如PM2.5（直径小于2.5微米的颗粒），与许多人类健康状况（如哮喘、心脏病）有关，并影响地球表面的辐射平衡（与气候有关）。挥发性有机化合物在决定大气的氧化能力（地球从大气中清除污染物的能力）方面也起着关键作用，而且越来越明显的是，挥发性有机化合物对室内空气污染有很大的影响。在极地地区，挥发性有机化合物的生物和光化学生产发生在冰雪界面和海洋表面。然而，在北极大气中的挥发性有机化合物形成的生态地球化学循环仍然很少描述，与未知的反馈响应北极海冰的下降。随着我们对大气过程的了解增加，计算机模型变得更加复杂，需要更好的测量，包括分析灵敏度（测量更少量），化学形态（识别和测量更大范围的化合物）和速度（更快的响应时间，使我们能够研究，例如，从移动的飞机或测量快速通量）。这将有助于我们了解控制这些通常复杂的大气相互作用的基本原理。对于VOC测量，质子转移反应飞行时间质谱仪（PTR-ToF-MS）在这方面将有很大的好处，并将在广泛的测量平台上部署（飞机、实验室/舱研究、天文台）和专题研究领域（全球大气成分，室内/室外空气质量，机理研究，FAAM飞机目前使用的PTR-QMS是17年前购买的。它基于四极检测系统，这限制了强大的PTR技术的能力。这些缺陷包括低质量分辨率（不能分辨相等质量的化合物）、必须预先选择有限数量的化合物（通常约10）、低灵敏度，特别是在较高质量（>100 Da）时。因此，我们建议用最先进的PTR-ToF仪器取代目前的PTRMS，这将有助于使FAAM飞机保持在全球大气研究的最前沿。PTR-ToF的优点包括：（1）测量的化合物数量大幅增加（ToF记录了宽质量范围内的所有质量，而四极杆仅记录了少量预选化合物）;（2）改进的质量范围（1-1000 Da）在质量>100 Da时灵敏度没有损失;（3）灵敏度提高（检测下限）;（4）更高的质量分辨率（例如，四极杆不能区分异戊二烯（质量68.117），一种重要的生物源化合物，和呋喃（质量68.075），生物质燃烧的产物;（5）更快的扫描;（6）选择性试剂电离（不同离子源试剂的使用允许改进仪器的特异性，在独特的RVG-空气-海-冰室中部署PTR-ToF-MS将允许在受控环境中研究VOC生产过程，提高我们对海冰地区挥发性有机化合物循环关键参数的理解。除了RvG-ASIC，PTR-ToF-MS还将为极地海洋的实地活动开辟新的途径，例如增加航运活动对北极空气质量的影响。