Analysis of particulate matter using EDXRF
Energy Dispersive X-ray Fluorescence (EDXRF) is a fast, accurate and non-destructive method for the analysis of a wide range of elements in particulate matter collected onto filters.
How does it work?
The system consists of a source, a sample and a detection system. The source is the x-ray tube which produces the x-rays, the sample is the filter you want to analyse and the detection system measures the radiation from the sample.
The bulk radiation coming from the sample can be separated into the radiation coming from individual elements because each element has a specific characteristic energy.
In contrast to wavelength dispersive systems, in EDXRF the use of 3D optics means that the X-ray path is in two perpendicular planes. This yields a very low background radiation level and allows the determination of low elemental concentrations.
Sample preparation
Filters are loaded directly into the EDXRF which reduced the potential for contamination. Collected PM is analysed directly on the filter surface. The filter is available for further testing following EDXRF analysis, e.g. ion chromatography.
Which elements can we analyse for?
We have the capability to analyse for the majority of elements with atomic numbers between Al and Pb. The accuracy and precision of measurements increases and the limit of detection goes down as the atomic number increases.
For selected elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, Pb) we compare results of each analysis with a NIST Standard Reference Material (SRM) to ensure inter-comparability between labs.
What samples can we analyse?
We can analyse samples of particulate matter collected onto Teflon filters. The instrument output is in μg/cm2. With known air flow rate and sampling duration, this result can then be converted to ng/m3 or μg/m3. We can test blanks and subtract the result from sampled filters.