Reliable compositional analysis of airborne particulate matter beyond the quantification limits of total reflection X-ray fluorescence

In this work, the reliability of total reflection X-ray fluorescence (TXRF) analysis for providing information on the absolute chemical composition of airborne particulate matter collected in a size fractionated manner by means of cascade impactors is investigated. It is shown that grazing incidence X-ray fluorescence (GIXRF) provides the means for a critical assessment of the validity of quantification performed using TXRF by a controlled variation of the excitation conditions. Furthermore, we demonstrate that GIXRF allows expanding the dynamic range of mass depositions that can be investigated. It is also discussed that the physically traceable quantification approach used, which does not require calibration samples, can be transferred to benchtop or portable commercial TXRF instrumentation.