Overview
EN ISO 4946:2016 - "Steel and cast iron - Determination of copper - 2,2'-Biquinoline spectrophotometric method" is a CEN-adopted international standard specifying a spectrophotometric procedure for measuring copper content in steel and cast iron. The method is applicable to copper mass fractions from 0.02 % to 5 % and is commonly used in metallurgical and quality‑control laboratories to provide reliable, traceable copper determinations.
Key topics and technical requirements
- Principle: Dissolve a test portion, remove interfering acids by fuming with perchloric acid, reduce Cu(II) to Cu(I) with ascorbic acid and form a coloured complex with 2,2'-biquinoline (cuproine). Measure absorbance at about 545 nm.
- Analytical range: Suitable for copper mass fractions between 0.02 % and 5 %.
- Reagents: High-purity iron (for blanks), hydrochloric, nitric and perchloric acids, dimethylformamide (DMF), ascorbic acid, 2,2'-biquinoline solution, and certified copper standard solutions (1 g/L and 0.05 g/L).
- Apparatus: Class A volumetric glassware (ISO 648, ISO 1042), a spectrophotometer with 2 cm or 4 cm optical path cells, and standard laboratory equipment.
- Procedure highlights:
- Typical test portion ≈ 0.5 g.
- Parallel blank tests using high‑purity iron.
- Fuming with perchloric acid to remove HCl/HNO3 and dehydrate silica.
- Colour development, preparation of compensating/ calibration solutions, and construction of a calibration graph for quantification.
- Safety notes: The standard warns about hazards of perchloric acid (explosive vapours with organics or ammonia) and dimethylformamide (toxic; use gloves and fume hood).
- Quality and reporting: Includes sections on sampling (ISO 14284), calibration, expression of results, and precision (repeatability and reproducibility) plus test report requirements.
Applications and users
- Who uses it: Metallurgical laboratories, steelmakers, foundries, third‑party testing and inspection bodies, and regulatory/standards compliance teams.
- Practical uses:
- Routine quality control of steel and cast iron grades.
- Incoming material verification and batch release testing.
- Failure analysis and alloy composition verification.
- Regulatory compliance and certification where accurate copper quantification is required.
Related standards
- ISO 14284 - Sampling and preparation of samples for chemical composition analysis
- ISO 3696 - Water for analytical laboratory use
- ISO 648, ISO 1042 - Laboratory glassware specifications
- Supersedes EN 24946:1990
EN ISO 4946:2016 is a standardized, validated spectrophotometric method for accurate copper determination in ferrous materials, making it essential for laboratories focused on material composition, quality assurance, and metallurgical control.
