An X-ray fluorescence method for direct-on-filter quantification of airborne particulate metals using a handheld...

Area of Science:

• Environmental Science
• Analytical Chemistry
• Occupational Health

Background:

• Accurate quantification of airborne particulate metals is crucial for environmental monitoring and occupational exposure assessment.
• Traditional methods can be time-consuming and resource-intensive, necessitating development of faster, field-deployable techniques.
• Handheld X-ray fluorescence (XRF) offers potential for rapid, on-site elemental analysis.

Purpose of the Study:

• To develop and validate a direct-on-filter method for quantifying airborne particulate metals using handheld XRF.
• To evaluate commercial calibration filters and introduce a simplified, cost-effective in-house calibration method using Certified Reference Material (CRM).
• To assess the performance of handheld XRF for exposure assessment, comparing it with established spectroscopic techniques.

Main Methods:

• A direct-on-filter quantification method was established using a handheld X-ray fluorescence (XRF) analyzer.
• Calibration curves were generated using both commercial single-element filters and in-house spiked CRM filters (single and multi-element).
• Method performance was evaluated for linearity, detection limits, and compared against Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) using Bland-Altman analysis.

Main Results:

• The handheld XRF analyzer demonstrated excellent linearity (R² ≥ 0.994) across various mass loadings.
• Detection limits ranged from 0.03-0.35 µg cm⁻², suitable for assessing occupational exposure limits for elements like Cr, Mn, Fe, Co, Ni, Zn, As, and Pb.
• Multi-element calibration using the developed method showed reduced bias and improved precision compared to ICP-OES.

Conclusions:

• The direct-on-filter handheld XRF method provides a rapid, cost-effective, and accurate means for quantifying airborne particulate metals.
• The simplified CRM spiking calibration technique is practical for in-field or laboratory use.
• Handheld XRF is a valuable tool for onsite exposure assessment, complementing advanced laboratory techniques like ICP-MS and ICP-OES.