TXRF analysis of airborne particulate matter captured in liquid medium using a cyclone bioaerosol sampling approach

A deep investigation of the aerobiome is necessary to assess air quality and the effect of environments on people's health. Characterization of airborne particulate matter (PM) is essential to study inorganic elements present in aerobiome. This study proposes a proof-of-concept method integrating an innovative liquid-based sampler, named Corlios Micro®, with Total Reflection X-ray Fluorescence (TXRF) analysis for rapid and multielemental analysis of airborne PM. TXRF is a suitable analytical technique since it requires small sample amount for analysis, making it ideal for low masses collected in liquid. Nevertheless, sampling in liquid medium poses some challenges associated with the heterogeneity and representativeness of the sample. To address these effects, we compared two sample preparation approaches - pre-concentration and lyophilization. Pre-concentration was applied because of its simple procedure and fast analysis time. This approach revealed low repeatability, which pointed to the problem of representativeness in highly dilute suspensions for the chemical analysis. On the other hand, lyophilization, which enabled the analysis of the whole collected sample, demonstrated low variability between replicates. This sample preparation method allowed to quantify the concentration of elements and identify the differences among various locations in indoor and outdoor sites. This optimized procedure demonstrates the potential of combining TXRF analysis with liquid-based airborne PM sampling for environmental exposure assessment in complex indoor and outdoor environments.