Assessment of calibration methods for Pb-loaded aerosol filters analysed with X-ray fluorescence under grazing incidence

Long-term exposure to air pollution causes negative health effects and in particular can lead to reduced lung function, respiratory infections, and aggravated asthma. To take actions against environmental pollution it is necessary to gather knowledge about the composition and concentration of air pollutants, especially particulate matter (PM). The European Community is encouraging its Member States to assess the ambient air quality by adopting common methods and criteria. In view of the complexity of the task, any type of analysis, either qualitative or quantitative, is relevant for identifying the presence of potentially toxic elements in PM filters, such as Pb. The most used analytical methods for PM filter analysis are Atomic Absorption Spectrometry and Inductively Coupled Plasma Mass Spectrometry. Besides, X-ray based techniques are gaining interest for PM analysis, as those are faster and cheaper, do not need any sample pre-treatment and are largely non-destructive. In this paper, Pb-loaded reference air filters are measured by X-ray fluorescence (XRF) under grazing incidence conditions using commercial instruments equipped with a Mo tube. This setup presents some advantages such as a broader illuminated sample area and an enhancement of the fluorescence emission. Calibration curves are built following the empirical and theoretical approaches to retrieve measurements parameters such as repeatability, limits of detection and quantification.