Development and application of analytical methods

Methods for Non-Exhaust Pollutants
Samples of PM10 collected within the Hatfield Tunnel, UK during sampling campaigns are being analysed for metal and organic concentrations using ICP-AES and GC/MS respectively. Work carried out during the first sampling campaign illustrated the feasibility of the overall methodology of chemically analysis of species associated with sampling particulate matter and the use of receptor modelling to apportion the sources was proven. Development of the sample digestion processes was undertaken to further improve the methodology to achieve higher analytical sensitivities for a number of species.

An investigation was carried out looking at how the digestion of atmospheric particle samples could be improved to determine metal concentrations. The examination of different acid matrices such as hydrofluoric acid along with different digestion processes such as microwave digestion has been undertaken. This has led to the development of a sampling method using Partisol samplers using Teflon filters, which could be employed alongside HiVol samplers. The additional Teflon filters samples will improve the detection of elements such as Al, Ca, Mg, Ba and Na which are associated with resuspended road dust and brake wear, and make a large contribution to urban particulate matter.

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High Volume and Partisol samplers (Left) within the Hatfield Tunnel, Accelerated Solvent Extractor (ASE) (upper right) Microwave Digester (lower right)

As the samples are also analysed for PAHs and Benzothiazole, work has been undertaken to develop a method to extract these compounds from the samples. The combined organic and metal data will help explain a large proportion of the particle mass, which in turn will improve the results of the source apportionment study. This will assist the investigation of non-exhaust emissions within the PM10 size fraction and unable the quantification of their emissions within the urban atmosphere

References
Martin S, Sokhi R.S and Mao H. (2007). Investigation of metal concentrations within PM10 particles using tunnel sampling techniques, 6th International Conference on Urban Air Quality, Limassol, Cyprus.
Funding provided by the NERC, BOC Foundation. Analytical services and expertise utilised at the NERC ICP-AES and NERC LC-MS facilities are acknowledged with special thanks to Dr Emma Tomlinson (Royal Holloway, University of London) and Dr Ian Bull (Bristol University).