ISO 1812:1976 PDF

Overview

ISO 1812:1976 specifies a spectrophotometric method for determining iron content in copper alloys using the 1,10‑phenanthroline reagent. The procedure is applicable to iron concentrations up to 0.4 % (m/m) and defines principle, reagents, apparatus, sampling, analytical procedure, calibration and reporting requirements. The method is routinely used in chemical analysis and quality control of copper and copper‑alloy products.

Key topics and technical requirements

• Scope and principle: Extraction of iron as an iron(III)‑chloro complex into an organic phase, reduction and formation of the iron(II)–1,10‑phenanthroline coloured complex, and spectrophotometric measurement at the wavelength of maximum absorption (typically ~510 nm).
• Detection range: Valid for iron contents from trace levels up to 0.4 % (m/m), with recommended aliquots and dilutions for different concentration ranges.
• Reagents: Uses methyl isobutyl ketone (MIBK) for extraction, hydrochloric acid (various concentrations) for dissolution and phase washes, hydrogen peroxide for sample digestion, ascorbic acid as a reducing agent, and a buffered 1,10‑phenanthroline solution (pH ≈ 6.5 ± 0.1).
• Apparatus: Ordinary laboratory glassware and a spectrophotometer with 2 cm optical path cells.
• Calibration and blanks: Preparation of iron standard solutions and a calibration curve (0–200 µg Fe) is required; a blank test must be run in parallel and used to correct results.
• Procedure highlights: Dissolve the test portion (typically 5 g) with HCl and H2O2, extract iron into MIBK, re‑extract into aqueous ascorbic acid, form the phenanthroline complex and measure absorbance within 30 minutes.
• Expression of results: Results are calculated and reported as % m/m iron using specified multiplication factors according to the aliquot and dilution used.

Applications and users

This standard is relevant for:

• Quality control laboratories in copper refineries and foundries
• Metallurgical and materials testing laboratories performing chemical analysis of copper alloys
• Manufacturers and purchasers verifying alloy composition and impurity levels
• Regulatory or conformity assessment bodies requiring standardized test data

Practical uses include verifying iron impurities that affect electrical, mechanical or corrosion properties of copper alloys, and supporting material certification and acceptance testing.

Related standards

• ISO/R 1811 - Chemical analysis of copper and copper alloys: Sampling of copper refinery shapes (referenced for sampling procedure)
• Developed under ISO/TC 26 (Copper and copper alloys)

Keywords: ISO 1812, copper alloys, iron content, 1,10‑phenanthroline, spectrophotometric method, chemical analysis, methyl isobutyl ketone, calibration curve, spectrophotometer.