Analysis of Trace and Major Elements in Steel by ICP-AES

Significance of the Topic

Accurate multi-element analysis of steel is critical for quality assurance, performance control and failure prevention across construction, transportation and manufacturing industries. Steel composition spans orders of magnitude—from trace impurities at mg/kg levels to major alloying components at weight-percent levels—so analytical techniques must deliver wide dynamic range, robustness to high-salt matrices and reliable trace-level detection. The combination of inductively coupled plasma atomic emission spectrometry (ICP-AES) with optimized sample introduction and vacuum-optics expands analytical capability for routine and research laboratories handling complex steel matrices.

Objectives and Study Overview

This application study evaluated the performance of the Shimadzu ICPE-9820 multitype ICP-AES for simultaneous analysis of trace and major elements in a stainless-steel certified reference material (NSTM SUS570-1). Goals included demonstrating accuracy against certified values across a broad concentration range, assessing methods to mitigate salt deposition and memory effects, and illustrating instrumental features (dual-view detection, vacuum spectrometer) that improve sensitivity and throughput.

Methodology

• Sample: Stainless-steel certified reference material NSTM SUS570-1.
• Pretreatment: 1 g sample heated and dissolved in 60 mL mixed acid (HCl : HNO3 : H2O = 3:1:4), diluted to 100 mL to produce stock solution. Three independent preparative replicates were prepared.
• Major-element measurement: Stock diluted 25× with dilute HCl; yttrium (Y) added as an internal standard at 20 mg/L. Quantification by external calibration (calibration-curve method) using internal standard correction.
• Trace-element measurement: Stock diluted 2× with purified water; standard-addition calibration used to compensate for matrix effects for low-level analytes.
• Calibration strategy: Multiple calibration ranges generated by selecting axial (AX) or radial (RD) view and alternative wavelengths to cover different concentration regimes; software auto-selects appropriate curve per analyte/sample.

Instrumentation Used

• Instrument: Shimadzu ICPE-9820 multitype ICP-AES with vacuum spectrometer (enables rapid startup and access to vacuum ultraviolet region, < 190 nm).
• Nebulizer: 10UES.
• Spray chamber: Twister Spray Chamber HE (improved particle-size selection for high-salt matrices).
• Torch: Torch for high-concentration salt solution samples (vertical torch orientation mitigates memory effects).
• Autosampler: AS-10.
• Accessories: Water bubbler to suppress salt deposition on sampling components.
• Operating conditions (typical): RF power 1.40 kW; plasma gas 15.0 L/min; auxiliary gas 1.20 L/min; carrier gas 0.70 L/min (0.65 L/min used for trace analysis). Observation modes: axial (AX) for high sensitivity and radial (RD) for high-concentration samples.

Main Results and Discussion

Quantitative measurements combined triplicate independent sample preparations with triplicate measurements per preparation (nine results per analyte) to evaluate both accuracy and reproducibility. Major and trace element results showed close agreement with certified values across the examined elements:

• Major elements: Chromium measured 18.17% (certified 18.14%); Manganese 1.96% (1.95% certified); Molybdenum 2.58% (2.59% certified); Nickel 8.21% (8.21% certified). Standard deviations and repeatabilities were very low (e.g., relative repeatability typically well below 1%), indicating excellent precision.
• Trace elements: Copper, phosphorus and tin measured values closely matched certified concentrations (e.g., Cu ≈ 0.0509% measured vs 0.0515% certified; P ≈ 0.0421% vs 0.0423% certified; Sn ≈ 0.0097% vs 0.00976% certified). Calculated solid detection limits were low (example: Cu solid DL ≈ 0.0002% by the method described).
• Silicon: Measured as reference but noted issues with long-term stability after the mixed-acid pretreatment; results treated as indicative rather than definitive.

Instrumental and sample-introduction choices directly supported these outcomes. The Twister spray chamber produced finer aerosol selection improving matrix handling for high-salt digestates. The torch designed for high-salt solutions combined with a water bubbler reduced salt deposition, maintaining sensitivity for low-dilution trace analyses. The dual-view capability allowed flexible dynamic-range coverage: radial observation for higher-concentration lines and axial for trace-sensitive lines. Use of a vacuum spectrometer enabled reliable access to shorter wavelengths and faster system readiness.

Benefits and Practical Applications of the Method

• Wide dynamic range: Simultaneous quantification from trace levels to major alloying elements in a single instrument with automated selection of calibration ranges reduces analysis time and postprocessing.
• Robustness to saline/high-matrix samples: Dedicated torch, Twister chamber and water-bubbler minimize salt deposition and memory effects—critical for low-dilution analyses of steel digests.
• High throughput and rapid startup: Vacuum optics and multiview observation streamline workflows for routine QA/QC and production laboratories.
• Good accuracy and precision versus certified materials: Demonstrates suitability for certification testing, incoming material inspection and process control in steel manufacturing.

Future Trends and Opportunities

• Further integration with ICP-MS or hyphenated systems to expand detection capability (multi-isotope confirmation, lower trace limits) for problematic elements.
• Advanced aerosol management: Aerosol dilution, desolvation and novel spray-chamber designs to further suppress matrix effects and improve sensitivity for volatile and refractory elements.
• Automation and data analytics: Automated sample prep workflows, real-time drift correction and chemometric tools to enhance throughput and data quality in high-volume testing environments.
• Extended spectral access: Enhanced vacuum-optic designs to exploit VUV emission lines for elements with few suitable visible/UV transitions.
• Miniaturized or low-power plasma sources for field or near-line monitoring where portability and rapid screening are advantageous.

Conclusion

The ICPE-9820 ICP-AES system, combined with appropriate sample-preparation and sample-introduction strategies (Twister spray chamber, high-salt torch, water bubbler, dual axial/radial observation and vacuum spectrometer), provides accurate, precise and reproducible analysis of both major and trace elements in stainless-steel matrices. The method demonstrated close agreement with certified reference values and robust handling of high-salt digests, making it well suited for routine metallurgical QA/QC and research applications where broad dynamic range and rapid turnaround are required.

References

1. Du J., Hashimoto S., Analysis of Trace and Major Elements in Steel by ICP-AES, Shimadzu Application News (ICPE-9820), First Edition Sep. 2026.
2. Shimadzu Application News No. J112, Simultaneous Analysis of Trace and Major Elements in Iron and Steel by ICPE-9820.
3. Shimadzu Application News No. 01-01207-en, Trace Element Analysis of Steel Using ICP-MS.