Details of Award
NERC Reference : NE/K008110/1
IDENT: Novel approaches to the measurement of atmospheric VOC mixtures using soft chemical-ionisation mass spectrometry - drift-tube techniques
Training Grant Award
- Lead Supervisor:
- Professor W Bloss, University of Birmingham, Sch of Geography, Earth & Env Sciences
- Grant held at:
- University of Birmingham, Sch of Geography, Earth & Env Sciences
- Science Area:
- Atmospheric
- Overall Classification:
- Atmospheric
- ENRIs:
- Global Change
- Natural Resource Management
- Pollution and Waste
- Science Topics:
- None
- Abstract:
- Natural and anthropogenic processes emit a wide variety of volatile organic compounds (VOCs) into the atmosphere. Many have different chemical properties, affecting their contribution to the production of ozone and secondary organic aerosol, and their toxicity. There is a critical need for analytical approaches to distinguish such compounds in the complex mixture that is ambient air. Traditional GC methods have limited scope to study rapidly changing atmospheric composition, which may arise from emissions, chemical processing and meteorology. Alternatively, an ionisation technique coupled to a mass spectrometer, through which most VOCs can be measured (almost) simultaneously, and at high temporal frequency, such as PTR-MS (Proton Transfer Reaction Mass Spectrometry) may be used - however compound identification using MS approaches is challenging, as is not always clear which compounds are contributing to a given mass-charge ratio (m/z): many VOCs may be isobaric - i.e. have the same whole-number molecular mass (or are isomeric, with identical molecular masses), and may fragment. The aim of this project is to develop the controlled application of fragmentation patterns to distinguish between isobaric atmospheric VOCs, using the PTR-MS approach. Our proof-of-concept work shows that the fragmentation patterns of such VOCs vary in a systematic manner with the operating parameters of the PTR-MS system (such as the reduced electric field strength (E/N) and ionising agent) - and that these variations differ between isobaric (and isomeric) species. A recent technical innovation in PTR-MS, the ion funnel, substantially increases the instrument sensitivity, and also provides additional parameters (RF field strength, frequency) which may be utilised to further systematically control fragmentation. Page 1 of 13 Date Saved: 10/10/2012 09:00:53 Date Printed: 10/10/2012 11:43:19 Knowledge Transfer Within this project, the student will characterise the dependence of VOC fragmentation upon PTR-MS operating parameters; develop algorithms to analyse (or fit) these fragmentation patterns to series of mass spectra collected under different conditions, and establish operational protocols to most effectively probe the controlled fragmentation dependence of a given set of target analytes, at high time resolution. The student will then apply the improved analytical capability to (a) detection of isoprene, and studies of (aspects of) its degradation chemistry, and (b) resolution between the isobaric monoterpene isomers, and between isobaric aromatic compounds. Isoprene (C5H8) is the dominant biogenic VOC emitted globally, and a major contributor to O3 and SOA production, however within the atmosphere potential interferants are frequently present at the C5H9+ parent peak mass of m/z 69. The isoprene degradation products methyl vinyl ketone (MVK) and methacrolein (MACR) are also key atmospheric components - as these are both C4H6O structural isomers, conventional MS approaches cannot distinguish between them. The C10H16 monoterpenes differ widely in their structure, and hence reactivity and atmospheric chemical role. Isobaric aromatic VOCs such as ethylbenzene and o/m/p-xylene again differ in their atmospheric impacts, sources and perhaps most significantly in their toxicity - the project will demonstrate the capability to distinguish between these species, initially using test mixtures, followed by atmospheric measurements at background and roadside locations. Finally, we will apply the technique to study isoprene degradation in a small reaction chamber within our laboratory, and assess the (independent) production of the MVK and MACR products. The studentship will develop new analytical capability, demonstrate its application to a range of current measurement challenges in atmospheric science, and provide the student with a broad training in both analytical chemistry and atmospheric science, within the academic and
- NERC Reference:
- NE/K008110/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- Analytical Sci and Tech
This training grant award has a total value of £68,671
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - RTSG | Total - Student Stipend |
|---|---|---|
| £13,978 | £5,500 | £49,194 |
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