Analysis of impurities in non-ferrous metals and nickel- based superalloys using single quadrupole inductively coupled plasma mass spectrometry (ICP-MS)

Significance of the Topic

Understanding trace impurities and bulk composition in non-ferrous metals and nickel-based superalloys is essential for ensuring material performance in industries such as aerospace, automotive, electronics, and energy.

Accurate quantification of major elements, additives, and ultra-trace contaminants supports property optimization, quality control, and regulatory compliance.

Objectives and Study Overview

This study demonstrates a rapid and robust analytical method using single-quadrupole ICP-MS with Argon Gas Dilution (AGD) to measure 20 elements in pure metals and alloys.

The goals included verifying method linearity over a wide dynamic range, assessing detection limits, and validating accuracy and precision for both trace impurities and major matrix elements.

Methodology

Certified reference materials of nickel-based superalloys and single-element standards were digested in a mixture of HNO₃, HCl, and HF at 180 °C.

Diluted solutions (~0.1% total dissolved solids) were analyzed without further offline dilution.

Spike recovery tests (25 µg/L spikes in 1,000 mg/L matrix) and continuing calibration verification examined method accuracy and stability.

Used Instrumentation

An iCAP MSX single-quadrupole ICP-MS coupled with an iSC-65 autosampler was employed.

Key features included Argon Gas Dilution level 5, He collision mode (KED), glass cyclonic spray chamber (2.7 °C), PFA concentric nebulizer, PLUS torch, and Qtegra ISDS software.

Intelligent Matrix Handling minimized matrix exposure and downtime.

Main Results and Discussion

Detection limits ranged from sub-ppb to sub-ppm, with method detection limits in solid samples down to low µg/kg.

Calibration curves (R² > 0.9993) covered from 25 µg/L to 1,000,000 µg/L, demonstrating excellent linearity.

Spike recoveries for most elements fell between 85% and 105%, confirming accuracy under high-matrix conditions.

Interferences from polyatomic species were effectively reduced using He KED, although some isotope choices were adjusted (e.g., 82Se vs. 78Se) to avoid residual bias.

Long-term robustness testing (258 analyses over 9 hours) maintained internal standard recoveries within 83–112%, underlining method stability.

Benefits and Practical Applications

• High throughput: <3 minutes per sample including uptake and wash
• Wide dynamic range: trace to major element quantification without extra dilutions
• Robust matrix tolerance via integrated AGD and KED
• Accurate and precise results for quality control of metallurgical products

Future Trends and Opportunities

Integration of triple-quadrupole ICP-MS could further enhance interference removal for challenging isotope pairs.

Advances in sample introduction and automation may streamline high-matrix analyses even more.

Application of machine learning in data processing could improve detection limits and method development.

Conclusion

The single-quadrupole iCAP MSX ICP-MS with AGD provides a fast, accurate, and robust solution for multi-element analysis in non-ferrous metals and nickel superalloys.

Excellent detection limits, linearity, and long-term stability support its use in routine quality control and research environments.

References

1. Manecki, M.; Kutscher, D.; McSheehy Ducos, S. Accurate measurement of elemental impurities in metals and metal alloys using triple quadrupole ICP-MS. Thermo Fisher Scientific Application Note 43404, 2020.
2. Vincent, T.; Rantanen, M.; Kalliovaara, E.; Köymäri, H. Robust and accurate analysis of refined nickel using triple quadrupole ICP-MS. Thermo Fisher Scientific Application Note 44463, 2020.