Comparison of the Concentrations of Heavy Metals in PM2.5 Analyzed in Three Different Global Research Institutions Using X-ray Fluorescence

This inter-lab study aimed to evaluate the comparability of heavy metal concentrations in the same samples using three X-ray fluorescence spectrometers (XRFs) in three different global re-search institutions, namely a collaboration lab between Soonchunhyang University (Asan, Korea). and PAN (a branch of Malvern PANalytical, Seoul, Korea), RTI (Research Triangle Institute, NC, U.S.A), and Aerosol laboratory in Harvard University, Boston, U.S.A. Indoor air filter samples were collected from 8 homes using 3 filters in each household (n = 24) of individuals with asthma, and the same filter samples were sequentially analyzed separately in the collaboration lab Soonchunhyang-PAN, Harvard University, and RTI. Results showed the detection rates of most heavy metals (n = 25 metals) across the three institutions to be approximately 90%. Of the 25 metals, 16 showed coefficient of determination (R-2) 0.7 or higher (10 components had 0.9 or higher) implying high correlation among institutions. Therefore, this study demonstrated XRF as a useful device, ensuring reproducibility and compatibility in the measurement of heavy metals in PM2.5, collected from indoor air filters of asthmatics' residents.