Analysis of air filters using the ARL QUANT’X EDXRF Spectrometer

Significance of the Topic

Monitoring ambient particulate matter composition is crucial for assessing air quality, regulatory compliance and public health impacts. Fast, sensitive multi-element analysis of particles collected on air filters supports environmental surveillance in residential, industrial and urban settings.

Objectives and Study Overview

This application note evaluates the ARL QUANTX energy dispersive X-ray fluorescence spectrometer for quantifying elements from sodium to americium on air filters. The performance is benchmarked against US EPA Compendium Method IO-3.3, focusing on detection limits, throughput and analytical robustness.

Methodology and Instrumentation

• Instrument: ARL QUANTX bench-top EDXRF with silicon drift detector (30 mm2 active area, 135 eV resolution at Mn K-alpha), 50 W rhodium X-ray tube (4–50 kV), nine-position filter wheel, five collimators (1.0–8.8 mm), and automated sample changer (10 or 20 positions)
• Software: UniQuant for standardless elemental analysis; WinTrace for spectrum deconvolution, empirical calibrations and thin film modules
• Sample Handling: Direct analysis under vacuum without chemical preparation. Filters inspected and loaded into trays for 25–47 mm samples or larger manually up to 220 mm
• Excitation Conditions: Five optimized voltage and filter configurations ensure maximum sensitivity across low, mid and high atomic number elements. Each setting is measured for 300 seconds, with total run time around 25 minutes
• Calibration and Verification: Empirical calibrations based on MicroMatter thin film standards and blank films. Calibration accuracy confirmed using NIST SRM 2783 air particulate on filter media

Key Results and Discussion

• Spectral Quality: High resolution and tailored filters yield clear, well-separated peaks for both light and heavy elements, reducing overlap errors
• Detection Limits: Minimum detection limits (1σ) range from below 1 ng/cm2 for elements such as silicon and phosphorus to approximately 21 ng/cm2 for heavier species. Most values meet or exceed US EPA IO-3.3 requirements
• Comparative Performance: Tabulated and graphical comparisons demonstrate that the ARL QUANTX spectrometer achieves equal or superior MDLs for the majority of elements compared to the US EPA method

Benefits and Practical Applications

• Non-destructive, simultaneous multi-element analysis with minimal sample preparation
• High throughput and automated sampling support large-scale monitoring campaigns
• Rugged, field-transportable design with remote connectivity enhances flexibility for on-site studies
• Versatile software options enable both standardless and empirical quantification, reducing method development time

Future Trends and Potential Applications

• Integration into mobile laboratories for real-time air quality mapping and emission source tracking
• Emerging detector and X-ray source technologies may further improve sensitivity and broaden element coverage
• Advancements in automation and machine learning algorithms promise more robust spectral deconvolution and quality assurance workflows
• Expanded use in industrial process control, indoor air assessments, and regulatory compliance testing

Conclusion

The ARL QUANTX EDXRF spectrometer delivers exceptional sensitivity, stability and operational efficiency for air filter analysis. Its performance routinely meets or surpasses regulatory detection requirements, making it a powerful tool for environmental monitoring and pollution studies.

Reference

• US EPA Compendium Method IO-3.3: Determination of Metals in Ambient Particulate Matter
• NIST SRM 2783 Air Particulate on Filter Media
• MicroMatter Technologies Inc. Thin Film Standards