EDXRF Analysis of Chromium, Lead and Cadmium in Metals (Brass)

Significance of the Topic

The Restriction of Hazardous Substances (RoHS) directive drives the need to monitor toxic metals such as chromium, lead and cadmium in electronic components. Energy-dispersive X-ray fluorescence (EDXRF) offers a fast, non-destructive approach for screening various sample forms, supporting environmental and recycling efforts by ensuring regulatory compliance.

Objectives and Overview of the Study

This study evaluates the analytical performance of the Shimadzu EDX-720 EDXRF spectrometer for determining Cr, Pb and Cd in brass components commonly used in electronics. Key goals include establishing detection limits, assessing calibration linearity, and verifying method repeatability.

Methods

• Six brass samples spiked with known concentrations of Cr, Pb and Cd (calibrated by ICP/MS) were analyzed.
• Measurement duration was fixed at 300 seconds for each element under optimized voltage and current settings: 30 kV and 20 μA for Cr, and 50 kV with auto-adjusted microampere for Pb and Cd.
• Lower limits of detection (L.L.D.) were calculated using a standard formula incorporating the calibration constant, background intensity and counting time.

Used Instrumentation

• EDX-720 energy-dispersive XRF spectrometer with an Rh-target X-ray tube.
• Atmospheric condition: ambient air; measurement window: 10 mm diameter; dead time: 40%.
• Filter settings: none for chromium, Filter #1 for lead, Filter #2 for cadmium.

Main Results and Discussion

The method achieved detection limits of 33.9 ppm for Cr (Kα), 69.3 ppm (Lα) and 35.5 ppm (Lβ1) for Pb, and 8.2 ppm for Cd (Kα). Calibration curves exhibited good linearity, with accuracy values of approximately 23 ppm (Cr), 27 ppm (Pb Lα), 15 ppm (Pb Lβ1) and 4.3 ppm (Cd). A ten-fold repeatability study on a brass standard (160 ppm Cr, 510 ppm Pb, 140 ppm Cd) yielded practical coefficients of variation between 3.0% and 7.4%, aligning reasonably with theoretical expectations. The enhanced sensitivity stems from optimized filter selection and improved counting rate systems.

Benefits and Practical Applications

• Non-destructive and rapid screening suitable for in-line quality control.
• Ability to analyze solid components without complex sample preparation.
• Supports compliance with RoHS regulations in electronics manufacturing and recycling.

Future Trends and Opportunities

Further advancements may include optimized filter technologies, automated calibration routines, and integration with portable EDXRF platforms. Expanding the element range and refining data processing algorithms will enhance throughput and detection capabilities, benefiting environmental monitoring and circular economy initiatives.

Conclusion

The EDX-720 system delivers reliable quantification of Cr, Pb and Cd in brass with detection limits and repeatability suitable for regulatory screening. Its non-destructive workflow and ease of use make it a valuable tool for electronics and recycling industries.