Analysis of steel and its alloys using the GB/T 20125-2006 standard and an Agilent 5100 ICP-OES in dual view mode

Importance of topic

Accurate determination of elemental content in steel and its alloys is essential for ensuring product quality, performance and regulatory compliance. Elements such as sulfur and phosphorus must be strictly controlled at low levels to meet industry standards. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) offers the sensitivity, dynamic range, and throughput needed for routine quality control of steel grades in manufacturing environments.

Objectives and study overview

This application study evaluates the performance of the Agilent 5100 Vertical Dual View (VDV) ICP-OES, operated in dual axial/radial mode, following the GB/T 20125-2006 method for low-alloy steel. Key goals include assessing calibration linearity, detection limits, accuracy (via certified reference materials), and long-term stability over extended runs of challenging steel digests.

Methodology and instrumentation

The core workflow combines acid digestion, matrix-matched calibration, and dual-view ICP-OES measurement:

• Sample preparation: 0.5 g of steel CRM digested with HNO₃, HCl and HClO₄ on a hot plate, diluted to 100 mL in de-ionized water (≈0.5 % total dissolved solids).
• Calibration: Multi-element standards prepared from single-element stocks, matrix-matched with 5000 mg/kg Fe. Inter Element Correction (IEC) factors and Fitted Background Correction (FBC) used to address spectral overlaps.
• Instrument setup:
  
  • Agilent 5100 VDV ICP-OES with Vista Chip II CCD detector.
  • Dual-View quartz torch (vertical orientation), OneNeb nebulizer, double-pass glass cyclonic spray chamber, SPS 4 autosampler.
  • Operating conditions: RF power 1.5 kW, plasma gas 12 L/min, auxiliary gas 1 L/min, nebulizer flow 0.55 L/min; axial view for trace analytes (P, S, As), radial for major elements (Cr, Ni, Mn).

Main results and discussion

• Calibration linearity: All elements exhibited R² > 0.99999 across concentration ranges from sub-ppm (S, P) to percent levels (Cr, Ni), eliminating the need for additional dilutions.
• Detection limits: Method detection limits in the solid sample ranged from 0.23 mg/kg (Cu) to 5.2 mg/kg (Ni) in a 5000 mg/kg Fe matrix.
• Accuracy: Analysis of two steel CRMs (GH-135 6934 and GSBH 40031-93) yielded recoveries within ±10 % of certified values for 13 elements, confirming method validity.
• Long-term stability: Continuous analysis of a steel digest over 8 hours produced RSDs below 1.5 % for all elements, demonstrating robust plasma stability and reproducibility with the vertical torch and SSRF system.

Benefits and practical applications

Use of the Agilent 5100 VDV ICP-OES provides:

• High throughput through wide dynamic range and dual-view capability—trace and major elements measured without sample re-dilution.
• Reduced maintenance and consistent performance thanks to a vertical torch and solid-state RF system.
• Simplified method development via automated background correction and IEC settings stored in software templates.

Future trends and potential applications

Advances likely include further automation (inline dilution, robotic sample prep), enhanced software algorithms for real-time interference correction, expanded applications to complex matrixes (alloys, slags, environmental samples), and integration with data analytics platforms for predictive quality control.

Conclusion

The Agilent 5100 VDV ICP-OES, operated according to GB/T 20125-2006, delivers fast, accurate and highly reproducible multi-element analysis of steel. Its dual-view design, robust vertical torch and advanced software enable laboratories to meet stringent quality requirements with minimal sample handling and maintenance.

References

• Benefits of a vertically oriented torch—fast, accurate results, even for your toughest samples, Agilent Technologies publication, 2014, 5991-4854EN.
• Fitted Background Correction (FBC)—fast, accurate and fully automated background correction, Agilent Technologies publication, 2014, 5991-4836EN.