Prof. Rene Van Grieken, Micro-and Trece Analysis Centre (MiTAC), Department of Chemistry, University of Antwerp, Belgium.

Sala d'Actes de l'Institut de Ciencies de la Terra "Jaume Almera", ales 12h.

During last decades environmental agencies increased considerably the control and monitoring of atmospheric pollutants. Concerning heavy metals in atmospheric aerosols, there are serious concerns whether wavelength-dispersive XRF, applied nowadays by several national environmental agencies in Europe, will be capable of providing the detection limits necessary for assessing the decreasing "limit values" imposed by national authorities or foreseen by the EU Directive 96/62/EC towards 2010. Conventional EDXRF can normally not measure e.g. Cd and Hg via their less spectrally interfered K-lines. The potential of the new high-energy energy-dispersive XRF was therefore studied.
We have optimized and evaluated the new high-energy polarized beam energy-dispersive X-ray fluorescence (XRF) spectrometer Epsilon 5 (PANalytical, Almelo, The Netherlands) for quantitative analysis of aerosol samples deposited on filters. The advantages and the limitations of this spectrometer, relative to other relevant commercial units, will be discussed.
The detection limits were around 1 ng/cm² for most heavy metals, i.e. sufficiently low to meet the present Flemish and future European limits for e.g. Pb, Cd, As and Ni, with a 100-200 seconds counting time, for common sampling conditions. Other analytes usually present in very low concentrations (e.g. V, Cr, Sb) could be assessed as well. The natural background levels of many heavy metals could be measured.
Since many years, we have also been applying computer-controlled electron probe X-ray microanalysis (EPMA) with low-Z element capability for the quantitative analysis of numerous aerosol particles, e.g. in the context of cultural heritage applications, in many museums, caves with prehistoric wall paintings, cathedrals, etc. Some of these applications will be discussed as well.