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.

激进分子在大气中起着关键作用，即使他们的浓度非常小。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，而过氧自由基的性质和命运（RO2）对对流层臭氧化学具有重大影响。因此，非常重要的是，全球化学模型准确模拟OH和过氧自由基浓度。当前的自由基测量方法，尽管敏感，快速且经过良好证明，又大，昂贵且复杂，因此对自由基的观察在空间和时间上非常有限。结果是，尽管这些示踪剂本身的排放量不一定是准确的，但通常会针对长期寿命的示踪剂（例如甲基氯仿）测试OH估计。此外，测量过氧自由基的现有技术无法提供对模型验证模型的单个有机RO2的度量。因此，如果对自由基进行了广泛的长期测量来评估和改进模型，那将是巨大的好处，但这将需要当前尚不可用的小型，易于消除的系统。羟基和过氧自由基几乎可以肯定在其他重要过程中起着关键作用，例如从光化学诱导的积雪中的排放，这对极地对流层的化学影响很大。积雪中的详细根治性测量将对理解这种化学反应非常有益，但目前不可能。目前可用的动力学数据表明，小有机过氧自由基可以通过与高浓度NO的反应来快速和定量地转化为稳定的有机亚硝酸盐。该项目将通过转化为不同的有机亚硝酸盐化合物来量化有机过氧自由基的可行性，这些化合物可以通过高度敏感的负离子气相色谱 - 质谱法（Ni-GCM）来测量。此外，如果允许OH与烃反应以产生独特的过氧自由基，则亚硝酸盐转化方法也提供了测量OH的机会。这种新颖的方法比当前技术提供了更多有关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，并且也有可能测量CL和NO3自由基。激进的转换和采样与分析仪器不同，该工具应允许将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，以及一个非常适合测量积雪实验的自由基的采样系统。