Overview
ISO 4748:1984 - Copper alloys - Determination of iron content - Na2EDTA titrimetric method specifies a volumetric (titrimetric) laboratory procedure for measuring iron content in copper alloys. The standard defines the principle, required reagents and apparatus, step‑by‑step procedure, calculation of results and reporting requirements. It is applicable to all copper alloys listed in International Standards and uses a Na2EDTA (disodium EDTA) chelation/back‑titration approach.
Key topics and technical requirements
- Analytical principle: Separation of iron from copper by extraction of the iron(III)‑chloro complex into methyl isobutyl ketone, chelation of iron with excess Na2EDTA at pH 4.5, followed by back‑titration with a standardized zinc solution.
- Reagents (examples): Na2EDTA (0.05 mol/L standard solution), zinc standard solution (0.05 mol/L), hydrochloric acid, hydrogen peroxide, methyl isobutyl ketone, ethanol, lithium chloride, ammonium fluoride, thiourea, xylenol orange indicator, hexamethylenetetramine (pH adjustment).
- Apparatus: Ordinary laboratory glassware and a pH meter for accurate pH control around pH 4.5.
- Sample preparation: Dissolution of weighed test portion in hydrochloric acid with controlled oxidation (H2O2), phase extraction into organic solvent and washing to purify the iron fraction.
- Calculation: Results expressed as percentage by mass (% m/m). The standard provides the conversion factor (0.002793 g Fe per mL of 0.05 mol/L Na2EDTA) and the calculation to convert titration volumes (EDTA and zinc) into % iron.
- Performance data: Comparative tests in the standard report repeatability and reproducibility statistics (example sample averages and standard deviations are provided for method validation).
Practical applications and users
- Quality control and chemical analysis laboratories testing copper alloys (brasses, bronzes, other Cu‑based materials).
- Metallurgists and materials engineers verifying alloy composition for product specification compliance.
- Manufacturers of copper products, foundries and third‑party testing services requiring standardized, reproducible iron determinations.
- Useful in research and failure analysis where accurate iron quantification in copper matrices is needed.
Related standards and notes
- Developed by ISO/TC 26 (Copper and copper alloys). For complete traceability, use ISO 4748:1984 alongside other ISO standards governing copper alloy composition and sampling.
- The standard includes detailed reporting requirements (sample ID, method reference, results, any deviations) to ensure consistent documentation.
Keywords: ISO 4748:1984, copper alloys, iron content, Na2EDTA titrimetric method, EDTA titration, volumetric analysis, methyl isobutyl ketone extraction, zinc back‑titration.