Overview
EN ISO 4938:2016 - "Steel and iron - Determination of nickel content - Gravimetric or titrimetric method" is a CEN-adopted ISO standard that specifies validated laboratory procedures for measuring nickel content in steel and iron. The standard covers both gravimetric and titrimetric routes and applies to nickel mass fractions from 1 % to 30 %. It supersedes EN 24938:1990 and is intended for routine chemical analysis in metallurgical and quality‑control laboratories.
Key Topics
- Scope and applicability: Determination of Ni in ferrous materials for 1–30 % Ni.
- Analytical principles:
- Dissolution of test portion with appropriate acids.
- Precipitation of nickel as nickel‑dimethylglyoxime (Ni‑DMG).
- Removal/oxidation of interfering elements (e.g., cobalt oxidized by potassium hexacyanoferrate(III); copper removal by controlled potential electrolysis where applicable).
- Second precipitation to improve recovery and purity of the Ni‑DMG precipitate.
- Two determination options:
- Gravimetric method: dry and weigh the Ni‑DMG precipitate.
- Titrimetric method: dissolve precipitate, add excess EDTA.Na2, back‑titrate excess with zinc using xylenol orange indicator.
- Residual nickel analysis: Determination of nickel remaining in filtrates by atomic absorption spectrometry (AAS) (Annex C).
- Reagents and apparatus: Lists of required acids (HF, HNO3, HCl, H2SO4, HClO4), organic reagents (dimethylglyoxime), buffers, EDTA standard solution, and lab glassware conforming to ISO references (ISO 648, ISO 1042).
- Quality and safety: Instructions for sampling, precision data, calculation methods and hazards (e.g., warnings for hydrofluoric and perchloric acids).
Applications
Who uses EN ISO 4938:2016 and why:
- Steel and alloy manufacturers - to verify nickel content for product specification and alloy certification.
- Metallurgical and chemical analysis laboratories - routine compositional analysis and dispute resolution.
- Inspection and certification bodies - conformity assessment and acceptance testing of ferrous products.
- Research and development - method comparison, interlaboratory studies and method validation.
Practical value: provides a standardized, traceable procedure for reliable nickel quantification using well‑established chemical separation and measurement techniques.
Related Standards
Keywords: EN ISO 4938:2016, nickel determination, gravimetric method, titrimetric method, nickel in steel, dimethylglyoxime, EDTA titration, atomic absorption spectrometry, chemical analysis of metals.