Comparison of ED-XRF and LA-ICP-MS with the European reference method for the measurements of metals in ambient particulate matter.

A comparison study of the measurement of metals in ambient particulate matter collected on air filters using energy dispersive x-ray fluorescence (ED-XRF), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and wet chemical digestion followed by ICP-MS analysis according to the European `reference method? EN 14902, is presented. Whilst it is shown that the methods have a low systematic bias with respect to each other they do show a relatively high random variability. The uncertainty of each analysis has been estimated and compared with the requirements of the relevant European air quality legislation. This has tentatively shown that approximately 75 % of the analyses using ED-XRF and LA-ICP-MS meet the requirements of the legislation. However in order for ED-XRF and LA-ICP-MS to be a viable alternative to the EN 14902 method it is clear that more work is required to improve: calibration procedures and representative air quality reference materials for these methods (which are currently traceable to EN 14902 itself), and the sensitivity for ED-XRF analysis of Cd, where the limit of detection is unworkably high for daily low volume air samples.