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Details of Award

NERC Reference : NE/K008269/1

Portable chemosensors for atmospheric radicals

Training Grant Award

Lead Supervisor:
Professor V Chechik, University of York, Chemistry
Science Area:
Atmospheric
Overall Classification:
Atmospheric
ENRIs:
Environmental Risks and Hazards
Global Change
Pollution and Waste
Science Topics:
None
Abstract:
The chemical composition of the Earth's atmosphere is strongly affected by the presence of highly reactive free radicals such as hydroxyl radical (OH) and nitrate radical (NO3). These species are responsible for the oxidation of the trace organic compounds such as hydrocarbons. The photo-oxidation cycles proceed via intermediate formation of other free radicals, e.g., peroxyl (RO2) and hydroperoxyl (HO2). The knowledge of the concentration and distribution of free radical species in the atmosphere and the mechanisms controlling their chemical processing is therefore essential for understanding the control of air quality and climate issues. The measurement of the free radicals in the atmosphere however is not trivial. The concentrations of free radicals are extremely low, and their chemical lifetimes short, which places very strict requirements on the sensitivity of analytical methods. Very high reactivity of radicals makes offline analysis (e.g., taking samples for later analysis) impossible. A number of highly sensitive and selective methods for measuring atmospheric radicals have been developed; however all these techniques require high maintenance, bulky and expensive specialised equipment, do not permit identification of the whole structure of the radical intermediates, and often suffer from interferences. This proposal aims to address the above issues by developing PORTABLE and LOW COST chemosensors for quantitative and selective determination of atmospheric radicals. The main idea of the proposed research is that RADICAL SPECIES WILL BE CAPTURED IN A LIQUID WHERE THEY WILL UNDERGO SELECTIVE CHEMICAL TRANSFORMATIONS YIELDING STABLE PRODUCTS that can be analysed at a later time by a conventional analytical technique such as HPLC/MS. Surprisingly, this simple idea has not been exploited by researchers to any great extent. Conventionally, chemists capture free radicals with reagents called spin traps, and analyse the products by EPR spectroscopy. There are very few reports on trapping atmospheric radicals with spin traps, and a number of researchers explored radical trapping in wood and cigarette smoke. We have also successfully trapped radical intermediate in the gas phase catalytic reactions. However, spin traps and EPR spectroscopy have many important disadvantages, including poor stability of spin adducts and low sensitivity. This proposal will initially detect radicals using spin traps as the simplest and the most direct analysis method, but will then move to much more stable chemical reagents and more sensitive methods (e.g., HPLC/MS); the enhanced sensitivity/stability is key to successful measurement of very low radical concentrations found in the Earth's atmosphere. In order to facilitate rapid reaction of gas-phase radicals with the liquid traps, the project borrows design principles from established analytical techniques such as gas chromatography and gas indicator tubes. We believe the project has a potential to dramatically change our ability to monitor radical concentrations in the atmosphere. Any highly ambitious project carries an element of risk, however our joint expertise/knowledge and experience coupled to recent success with measuring radicals in gaseous catalytic reactions means that we can guarantee the successful determination of radicals in model systems - such as mechanistic chamber studies of important atmospheric processes. This makes the project highly suitable for a PhD student. This project is a new and exciting collaboration between two academics at York with complementary research expertise. It also offers some experimental chamber/fieldwork experience at the University of Leeds. It will therefore offer exciting multidisciplinary training opportunities for the student. The project will benefit from the very strong atmospheric chemistry and analytical links at York and training will be facilitated by the excellent graduate school arrangements.
Period of Award:
1 Oct 2013 - 30 Sep 2017
Value:
£70,771
Authorised funds only
NERC Reference:
NE/K008269/1
Grant Stage:
Completed
Scheme:
DTG - directed
Grant Status:
Closed

This training grant award has a total value of £70,771  

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FDAB - Financial Details (Award breakdown by headings)

Total - FeesTotal - Student StipendTotal - RTSG
£13,978£49,193£7,600

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