Comparison of Calibration Curves of Lead, Cadmium and Chromium in Zinc Alloy and Copper Alloy

Importance of the Topic

X-ray fluorescence (XRF) analysis offers rapid, non-destructive screening of metal alloys for toxic elements, making it indispensable for regulatory compliance (RoHS/ELV) and industrial quality control.

Objectives and Study Overview

This study evaluates and compares calibration curves for lead (Pb), cadmium (Cd) and chromium (Cr) in zinc (Zn) and copper (Cu) alloy matrices, and examines the applicability of a Zn-based calibration for mercury (Hg) analysis in Cu alloys.

Methodology and Instrumentation

The investigation employed certified Zn alloy reference materials (MBH Analytical) and Cu alloy samples (Sumitomo Metal Technology) with known concentrations of Cd, Pb, Cr and Hg (in Zn only). Calibration graphs of net intensity versus concentration were generated for Cd Kα, Pb Lβ1 & Lα, Cr Kα and Hg Lβ1.

Used Instrumentation

- Instruments: Shimadzu EDX-720 and EDX-GP XRF analyzers
- X-ray tube: Rhodium target
- Filters: #4 for Cd; #3 for Hg and Pb; #2 (EDX-720) or #3 (EDX-GP) for Cr
- Voltage/Current: 50 kV (30 kV for Cr), auto-adjusted µA
- Atmosphere: Air
- Measurement: 10 mm diameter, 300 s live time, 40% dead time

Main Results and Discussion

Calibration slopes for Pb, Cd and Cr were essentially identical in Zn and Cu alloys, indicating transferability of curves between matrices. The Zn alloy calibration also accurately quantified Hg in Cu samples. Quantitative tests on Zn sample 41× ZSC4 and Cu sample GBR2 showed deviations below 5% against certified values using either calibration curve, confirming interchangeability.

Benefits and Practical Applications

• Streamlined workflow by using a single calibration across Zn and Cu alloys
• Reduced instrument setup time and resource requirements
• Enhanced throughput for compliance testing and industrial QA/QC

Future Trends and Potential Applications

Future developments may include advanced multielement calibration algorithms, matrix-blind quantitation methods, automated real-time monitoring and expansion to additional alloy systems.

Conclusion

The study demonstrates that XRF calibration curves for heavy metals in Zn alloys are directly applicable to Cu alloys (and vice versa), and that Hg quantitation benefits equally from Zn-based calibration. This simplifies calibration management and supports efficient, accurate compliance screening.