ISO 4940:2025 PDF

Overview

ISO 4940:2025 specifies a flame atomic absorption spectrometric (FAAS) method for the determination of nickel content in steel and cast iron. The method covers nickel mass fractions from 0.002% to 0.5% and defines sample preparation, reagents, instrument performance criteria, calibration and reporting requirements. This second edition updates references, adds guidance on solution preparation and a bibliography, and replaces ISO 4940:1985.

Key Topics and Requirements

• Principle: Dissolve the test portion in appropriate acids, evaporate to fuming with perchloric acid, nebulize the final test solution into an air/acetylene flame, and measure atomic absorption of nickel at 232.0 nm or 352.5 nm (use 232.0 nm when sensitivity at 352.5 nm is insufficient).
• Scope: Applicable to nickel contents of 0.002% to 0.5% (mass fraction).
• Reagents and standards: Prescribes preparation of acid mixtures, a 1 g/L and 0.04 g/L nickel standard, and an iron base solution (40 g/L) to match matrix effects.
• Sample size: Test portion typically about 1.0 g; perform parallel blank tests using pure iron.
• Instrument performance criteria:
  • Limit of detection for nickel in a similar matrix: **