Overview
ISO 23597:2023 - Rare earth - Determination of rare earth content in individual rare earth metals and their oxides - Titration method describes a standardized analytical procedure to measure the total rare earth content in individual rare earth metals and their oxides. The method covers 15 elements (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium) and is intended for materials with high purity used across the rare earth supply chain.
Key Topics and Requirements
- Scope and applicability
- Applicable to individual rare earth metals (98.0 % to 99.5 % mass fraction) and oxides (95.0 % to 99.5 % mass fraction).
- Not applicable when relative rare earth purity < 99.5 %, total non-rare-earth metals > 0.5 %, or thorium/scandium/zinc > 0.1 % (mass fraction).
- Analytical principle
- Quantitative complexometric titration using EDTA at pH 5.5, with xylenol orange as the indicator.
- Interfering non-rare-earth ions (e.g., iron) are masked using sulfosalicylic acid prior to titration.
- Reagents & standards
- EDTA titrant (standardized), xylenol orange indicator, hexamethylene tetramine buffer (pH 5.5), sulfosalicylic acid, and zinc standard solution for EDTA standardization.
- Apparatus
- pH meter, automatic titrator, analytical balance, furnace and drying oven for sample conditioning.
- Sample preparation
- Metals: remove oxidized surface, prepare drillings/fragments and weigh promptly to minimize oxidation.
- Oxides: may be tested on an original, dried or ignited basis depending on reporting needs.
- Procedure, calculation and reporting
- Dissolution, masking, titration and calculation steps are specified; precision and test-report requirements are included.
Applications and Who Uses It
- Quality control laboratories in rare earth production and refining.
- Producers and traders for product specification, grading and pricing negotiation.
- Analytical laboratories providing compositional certification for rare earth metals/oxides.
- Downstream manufacturers (magnets, phosphors, catalysts) requiring verified feedstock purity.
- Supports fair trade, consistency, comparability and regulatory or contractual compliance across the rare earth supply chain.
Related Standards
- ISO 23597 references terminology and concepts from ISO 22444 series and cites statistical guidance such as ISO/TR 21074 for precision/permissible tolerances.
- Users should consult related ISO/TC 298 documentation for complementary test methods and terminology.
Keywords: ISO 23597:2023, rare earth titration method, rare earth content determination, EDTA titration, xylenol orange, rare earth metals, rare earth oxides, analytical method, quality control.