Testing radical assay by nitrite chemical entrapment (TRANCE)

通过亚硝酸盐化学包埋法 (TRANCE) 测试自由基测定

• 批准号: NE/H002502/1
• 负责人: David Oram
• 金额: $ 7.28万
• 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: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH002502%2F1
• 关键词: Testing; radical; assay; nitrite; chemical

Radicals play a pivotal role in the atmosphere even though their concentrations are extremely small. The hydroxyl radical (OH) controls the oxidation of most atmospheric pollutants, including many important greenhouse gases, whilst the nature and fate of peroxy radicals (RO2) has a major impact on tropospheric ozone chemistry. It is therefore extremely important that global chemistry models accurately simulate the OH and peroxy radical concentrations. Current radical measurement methods, whilst sensitive, fast and well proven, are large, expensive and complicated and therefore observations of radicals are very limited in space and time. A consequence of this is that OH estimations in global models are often tested against long-lived tracers (e.g. methyl chloroform) even though the emissions of these tracers themselves are not necessarily accurately known. Further, the existing techniques for measuring peroxy radicals are unable to provide a measure of individual organic RO2 with which to validate the models. Therefore it would be of immense benefit if there were extensive, long term measurements of radicals with which to assess and improve models, but this would need small, easily-deployable systems which are not currently available. Hydroxyl and peroxy radicals almost certainly play a key role in other important processes such as photochemically induced emissions from snowpacks which have a great influence on the chemistry of the polar troposphere. Detailed radical measurements within the snowpack would be hugely beneficial in understanding this chemistry, but are not currently possible. Currently available kinetic data suggests that small organic peroxy radicals can be converted rapidly and quantitatively into stable organic nitrites by reaction with high concentrations of NO. This project will examine the feasibility of quantifying organic peroxy radicals by this conversion into distinct organic nitrite compounds which can be measured by highly sensitive negative ion gas chromatography-mass spectrometry (NI-GCMS). Additionally, if OH is allowed to react with a hydrocarbon to produce a distinct peroxy radical, then the nitrite conversion method offers the opportunity to measure OH as well. This novel method offers more information on individual organic peroxy radicals than current technology affords, should be able to measure OH and organic peroxy radicals concurrently, and has the potential to also measure Cl and NO3 radicals. The radical conversion and sampling is distinct from the analysis instrument which should allow the future development of a small, low-cost sampling device suitable for the large scale deployments required to test global chemistry models, as well as a sampling system well suited to measuring radicals in snowpack experiments.

尽管自由基的浓度极小，但它们在大气中发挥着关键作用。羟基自由基 (OH) 控制着大多数大气污染物的氧化，包括许多重要的温室气体，而过氧自由基 (RO2) 的性质和命运对对流层臭氧化学具有重大影响。因此，全球化学模型准确模拟 OH 和过氧自由基浓度极其重要。目前的自由基测量方法虽然灵敏、快速且经过充分验证，但体积庞大、昂贵且复杂，因此自由基的观察在空间和时间上都非常有限。其结果是，全球模型中的 OH 估算通常会针对长寿命示踪剂（例如甲基氯仿）进行测试，即使这些示踪剂本身的排放量不一定准确已知。此外，现有的过氧自由基测量技术无法提供单个有机 RO2 的测量值来验证模型。因此，如果能够对根式进行广泛、长期的测量来评估和改进模型，那将会带来巨大的好处，但这需要小型、易于部署的系统，而目前尚不可用。羟基和过氧自由基几乎肯定在其他重要过程中发挥着关键作用，例如积雪的光化学诱导排放，这对极地对流层的化学有很大影响。积雪内详细的自由基测量对于理解这种化学反应非常有益，但目前还不可能。目前可用的动力学数据表明，小的有机过氧自由基可以通过与高浓度的 NO 反应，快速定量地转化为稳定的有机亚硝酸盐。该项目将研究通过将有机过氧自由基转化为不同的有机亚硝酸盐化合物来定量有机过氧自由基的可行性，这些化合物可以通过高灵敏度负离子气相色谱-质谱法（NI-GCMS）进行测量。此外，如果 OH 可以与烃反应产生独特的过氧自由基，那么亚硝酸盐转化方法也提供了测量 OH 的机会。这种新颖的方法提供了比现有技术更多的关于单个有机过氧自由基的信息，应该能够同时测量 OH 和有机过氧自由基，并且还具有测量 Cl 和 NO3 自由基的潜力。自由基转换和采样与分析仪器不同，分析仪器应该允许未来开发适合测试全球化学模型所需的大规模部署的小型、低成本采样装置，以及非常适合测量自由基的采样系统在积雪实验中。