Sensitivity Calibrations of K- and L-shell X-ray Lines for Elemental Analysis of Air Particulate Samples Using a Handheld XRF Spectrometer

The portability, ease of use, relative lower cost of procurement and simple maintenance of a handheld X-ray fluorescence analyzer makes it a potential alternative for air particulate analysis especially in highly polluted and economically disadvantaged regions of the world. Thus, this study assessed the performance of such analyzer in characterizing aerosol laden filters. Spectra of Certified Reference Materials (NIST 2783 CRM for aerosol filters) measured with a handheld X-ray fluorescence analyzer were calibrated and fitted using iterative nonlinear least-square fitting procedure provided by the International Atomic Energy Agency-Quantitative X-ray Analysis System. Elemental sensitivity calibration curves, method detection limits, uncertainty estimates of K- and L- X-ray lines in the elemental range 18 < Z < 39 and 47 < Z < 83 respectively were determined for four excitation conditions [High (Hi), Main (Ma), Light (Li) and Low (Lo)]. Signal counts for K alpha and beta (Ni, Zn, Se) and L alpha and beta (Pt, Te, Au) lines of the CRM's were used to validate the analytical method. Concentrations values were evaluated for trueness and precision. Hi excitation condition has the least sensitivity (5 times less than Ma, 30-40 times less than Lo and more than 100 times lower than Li) within varying range of atomic number. However, Hi (R-2 = 0.99) and Ma (R-2 = 0.96) condition had the best overall trueness and precision score within an acceptable relative standard deviation <= 6% for the six CRM's evaluated.