Overview
ISO 6351:1985 specifies a flame atomic absorption spectrometric (FAAS) method for the independent determination of silver (Ag), bismuth (Bi), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), lead (Pb) and zinc (Zn) in refined, wrought and cast nickel. The standard covers sample dissolution in nitric acid, preparation of nickel‑matched calibration solutions, spectrometric measurement and expression of results. It is intended for routine laboratory analysis and quality control of nickel and nickel alloys.
Key topics and technical requirements
- Analytical technique: Flame atomic absorption spectrometry (air‑acetylene, fuel‑lean flame) using single‑element hollow‑cathode or electrodeless lamps and specified resonance lines.
- Sample preparation: Dissolution of test portion in nitric acid (diluted), evaporation to a syrup, redissolution and dilution to a known volume. Typical test portions: nominal 5 g (Procedure A) or 2 g (Procedure B); larger masses may be used for inhomogeneous samples.
- Calibration strategy: Two sets of calibration solutions (A and B) with a nickel matrix match (e.g., 25 g Ni/L or 10 g Ni/L) to compensate non‑specific absorption and matrix effects. The zero member serves as the blank when the same batch of nitric acid is used.
- Concentration ranges: The method covers low and higher concentration ranges via Procedure A and Procedure B. The iron lower limit can be extended below 0.0025% (m/m) with specially prepared standards. The upper limits for Co and Cu can be raised to 2% (m/m) with a minor method modification.
- Quality and performance: Instrument performance parameters (see annex A) must be met; reproducibility and repeatability data were established through interlaboratory tests.
- Precautions & interferences: Avoid chloride contamination (critical for Ag determination); consult clause 10 for other potential interferences and corrective measures.
Applications and users
ISO 6351:1985 is used by:
- Metallurgical and nickel refining laboratories for chemical assay and composition control
- Quality control teams in manufacturers of nickel, nickel alloys and components
- Materials testing laboratories performing compliance testing for product specifications
- Research and interlaboratory comparison programs assessing analytical precision
Typical applications include verifying trace and minor element content in refined, wrought and cast nickel, process control during refining or alloying, and quality certification before shipment.
Related standards
- ISO 5725 - Precision of test methods (repeatability/reproducibility)
- ISO 1042, ISO 648, ISO 3851 (laboratory glassware and equipment standards referenced for volumetric and pipetting accuracy)
Keywords: ISO 6351:1985, nickel analysis, flame atomic absorption spectrometry, Ag Bi Cd Co Cu Fe Mn Pb Zn determination, nickel quality control, calibration matrix, sample preparation, analytical standards.