Development of single-compound reference materials on polytetrafluoroethylene filters for analysis of aerosol samples

Abstract

Single element/compound reference materials (RM) were generated from high purity salts or nanoparticles on 25 and 47 mm PTFE filters for use in calibration and quality checks of X-ray fluorescence (XRF) analysis. The aerosols were deposited using a custom-made aerosol generation system equipped with common ambient air particulate matter samplers. The mass loadings on the RM were determined based on gravimetric measurements and the stoichiometry of the deposits, and then confirmed by energy dispersive XRF, inductively coupled plasma mass spectrometry, and/or ion chromatography. Selected RM were demonstrated to have homogeneous deposits and be stable both short- and long-term when handled and stored properly. Overall, RM on PTFE filters with minimum loadings ~0.5 μg/cm2 and uncertainty ≤10% for Na, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Ce, and Pb have been generated. These gravimetrically certified RM are invaluable in calibrations of the XRF analyzers, as they are the only ones available on PTFE membranes with mass loadings typical of those collected from ambient air. In addition, these RM can be utilized to monitor instrumental performance over time and together with multi-elemental reference materials can help examine common artifacts in spectral analysis.