Overview
ISO 11652:1997 specifies a flame atomic absorption spectrometric (AAS) method for the determination of cobalt (Co) content in steel and iron. The method covers cobalt concentrations from 0.003% to 5.0% (m/m) and defines sample preparation, reagents, instrument performance criteria and calibration procedures using a cobalt hollow‑cathode lamp at 240.7 nm. This standard is intended for routine analytical control, certification and quality assurance in metallurgical laboratories.
Key topics and technical requirements
- Scope and principle
- Dissolution of a weighed test portion in hydrochloric, nitric and perchloric acids, followed by AAS measurement of the Co 240.7 nm line.
- Analytical range
- Applicable to cobalt contents between 0.003% and 5.0% (m/m).
- Reagents and standards
- Use analytical‑grade reagents and grade 2 water (ISO 3696). Preparation of cobalt standard solutions A, B and C (stock and diluted standards) is specified.
- Sample sizes and dilutions
- Test portion sizes are prescribed by expected Co level (e.g., ~1.0 g for ≤2.0% Co; ~0.50 g for 2.0–5.0% Co) with defined dilution steps to produce the final test solution.
- Calibration and matrix matching
- Calibration solutions are prepared in a pure‑iron matrix; blank tests use pure iron. Calibration spans several ranges with recommended standard volumes to ensure accurate calibration graphs.
- Instrument performance
- Atomic absorption spectrometer equipped with a cobalt hollow cathode lamp and air‑acetylene fuel‑lean flame. Performance criteria include:
- Precision limits for repeated absorbance measurements.
- Limit of detection: better than 0.05 µg Co/mL (for 240.7 nm).
- Characteristic concentration: better than 0.3 µg Co/mL.
- Graph linearity requirements across the concentration range.
- Interference control and optimization
- Recommendations for background correction (deuterium lamp) for highly alloyed steels (FeO molecular absorption) and a procedure to adjust flame conditions to compensate for nickel/chromium chemical interferences.
- Safety
- Warnings about perchloric acid vapours, acetylene hazards, UV exposure and proper burner maintenance.
Applications and users
- Practical uses:
- Quality control during steel and alloy production
- Incoming material inspection and certification
- Failure analysis and R&D of high‑performance alloys
- Regulatory or contractual composition verification
- Typical users:
- Metallurgical and chemical analytical laboratories
- Quality managers and metallurgists in steel plants
- Third‑party testing and certification bodies
Related standards
- ISO 14284 - Sampling and preparation of samples for determination of chemical composition (referenced)
- ISO 3696 - Water for analytical laboratory use
- ISO 385-1, ISO 648, ISO 1042 - Laboratory glassware standards
- ISO 5725 series - Accuracy (trueness and precision) of measurement methods
Keywords: ISO 11652:1997, cobalt determination, flame atomic absorption spectrometry, AAS Co, cobalt in steel, Co content analysis, sample preparation, calibration, limit of detection.