Evaluation of standardless EDXRF analysis for the determination of elements on PM10 loaded filters

Abstract

Energy Dispersive X-ray Fluorescence (EDXRF) was compared to Inductively Coupled Plasma Mass Spectrometer (ICP-MS) for the measurements of elements (Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Fe, Co, Ni, Mn, Cu, Zn, As, Br, Sr, Pb, Mo, Cd, Sn and Sb) in particulate matter (PM10) collected on Teflon and two types of quartz filters at different sites. Two different methods of EDXRF analysis, linear calibration and standardless analysis, were studied. For the linear calibration, Pb, Mn, Fe, Cu, Ti and Zn were found to be site and filter type independent whereas Ca was only site independent. The site effect was evidenced for K, As, Ni, and V for quartz filter. The standardless EDXRF analysis showed better results than linear calibrations except for As, Co and V for Teflon filters and Cr and V for quartz filters. The measurement uncertainty of standardless EDXRF analysis was estimated by establishing a model equation. The measurement uncertainty estimated with this model equation was confirmed by field experiments provided that elemental masses exceeded observed thresholds. It was found that standardless EDXRF analysis is able to quantify most of the elements studied, particularly on Teflon filters rather than quartz filters. The standardless EDXRF analysis complies with the data quality objectives (DQO) of European Directives to measure Pb in PM10 for three types of filters, even at concentrations lower than limit values (LV). The detection limits (MDL) of standardless EDXRF analysis for measuring As and Cd were found to be insufficient to meet the legislative requirements. The MDL of Ni was sufficiently low for measurements; however, measurement uncertainties remained higher than the DQO at the lower concentrations than LV.