Analysis of Steel and Its Alloys by ICP-OES Following the GB/T 20125- 2006 Standard

Importance of the Topic

Quality control of steel and its alloys is critical because even trace impurities such as sulfur and phosphorus can undermine mechanical strength, corrosion resistance and overall performance. Manufacturers rely on reliable multi-element analysis to certify product grades and comply with standards such as GB/T 20125-2006.

Objectives and Study Overview

This study evaluates the performance of the Agilent 5800 Vertical Dual View (VDV) ICP-OES combined with the AVS 7 sampling valve for simultaneous determination of 15 elements in low-alloy steel. Three certified reference materials (CRMs) are used to validate accuracy, detection limits, stability and compliance with the GB/T 20125-2006 standard.

Methodology

Samples were prepared by microwave digestion of 0.25 g CRM in a mixture of nitric, hydrochloric and hydrogen peroxide acids, then diluted to 50 mL to produce a 24 % aqua regia matrix. Calibration standards were matrix-matched in 24 % aqua regia over ranges selected by semiquantitative IntelliQuant Screening. Continuing calibration verification (CCV) and method detection limits (MDLs) were assessed using a 5000 mg/L iron blank.

Instrumentation

Measurements were performed on an Agilent 5800 VDV ICP-OES fitted with:

• SeaSpray concentric nebulizer and double-pass cyclonic spray chamber
• Agilent Easy-fit demountable VDV torch with 1.8 mm injector
• Advanced Valve System (AVS 7) seven-port switching valve and SPS 4 autosampler
• Vista Chip III detector covering 167–785 nm

Key software features include IntelliQuant Screening for wavelength selection, Early Maintenance Feedback and background correction methods (FBC, FACT and off-peak). Europium and lutetium (10 mg/L) served as internal standards to correct matrix and ionization interferences.

Main Results and Discussion

Method detection limits for trace elements ranged from 0.16 to 2.3 mg/kg using optimized background correction. Recovery studies on three steel CRMs showed all major and trace elements within ±10 % of certified values. Spectral overlaps from iron-rich matrices were effectively resolved by FACT or inter-element correction. Long-term stability was demonstrated by analyzing 217 samples over six hours, with QC measurements consistently within ±10 % of expected concentrations.

Benefits and Practical Applications

The combined 5800 VDV ICP-OES and AVS 7 system delivers:

• High sample throughput and reduced analysis time with rapid valve switching
• Wide dynamic range enabling major and trace elements in a single run
• Lower argon consumption and reduced maintenance demands
• Robust performance for routine steel QC laboratories

Future Trends and Opportunities

Advances in spectral deconvolution and automated maintenance feedback will further streamline method development. Integration with laboratory information management systems (LIMS) and expansion to other metal matrices can extend applicability. Continued improvements in detector technology promise even lower detection limits and higher throughput.

Conclusion

The Agilent 5800 VDV ICP-OES with AVS 7 meets the requirements of the GB/T 20125-2006 standard for multi-element analysis of steel. The method demonstrates accuracy, stability and robustness for both major and trace elements, providing a powerful tool for routine quality control of steel and its alloys.

References

• Standardization Administration of China GB/T 20125-2006. Determination of multi-element content of low-alloy steel using ICP-OES.
• Agilent Technologies. IntelliQuant Software for sample insight and method development. Publication 5994-1516EN.
• Agilent Technologies. IntelliQuant Screening for semiquantitative ICP-OES analysis. Publication 5994-1518EN.
• Agilent Technologies. Early Maintenance Feedback for ICP-OES. Publication 5994-2164EN.
• Agilent Technologies. Fitted Background Correction (FBC) for ICP-OES. Publication 5991-4836EN.
• Agilent Technologies. FACT Spectral Deconvolution Software. Publication 5991-4837EN.
• Agilent Technologies. Advanced Valve System (AVS) 6/7 Port Switching Valve. Publication 5991-6863EN.