Overview
EN ISO 11490:2023 - "Jewellery and precious metals - Determination of palladium - Gravimetry using dimethylglyoxime" - specifies a standardized gravimetric procedure to determine palladium content in homogeneous precious-metal alloys. The method is optimized for palladium contents preferably between 50 and 999 parts per thousand (‰) by mass. For fineness above 999 ‰, spectroscopy by difference (e.g. ISO 15093) is recommended. This edition (2023) supersedes EN ISO 11490:2016 and extends applicability beyond jewellery to a wider range of precious-metal alloys.
Key topics and technical requirements
- Analytical principle: dissolve sample in aqua regia, precipitate palladium as a dimethylglyoxime complex, ignite to produce a palladium “sponge”, and weigh gravimetrically.
- Silver handling: silver, if present, is separated as silver chloride (AgCl) before palladium precipitation (specific procedure provided).
- Correction for co‑precipitates: co-precipitated alloying elements are tested after re-dissolving the palladium sponge (for example by ICP‑OES) and corrections applied to the palladium mass.
- Reagents and apparatus: uses aqua regia, HCl, HNO3, dimethylglyoxime (aqueous and ethanol-saturated), reducing/inert gases, porcelain crucibles, muffle furnace (≥900 °C), ashless filter paper, and an analytical balance (0.01 mg readability).
- Procedure highlights: preliminary composition check (e.g., XRF), sample flattening, controlled dissolution and evaporation, staged addition of saturated dimethylglyoxime solutions, filtration/washing, ignition and weighing.
- Safety and quality: cautions for hazardous reagents (aqua regia, strong acids) and requirement to use analytical-grade reagents and distilled water. Sampling should follow ISO 11596.
- Method updates: removal of hydrofluoric and sulfuric acid from the method and harmonization with ISO 11210.
Applications and users
This standard is intended for:
- Assay offices and certifying bodies for jewellery fineness.
- Analytical laboratories testing palladium content in alloys and jewellery.
- Manufacturers and quality-control teams in jewellery and precious‑metal production.
- Regulatory and compliance labs requiring traceable, standardized palladium determination.
Practical uses include fineness certification (in conjunction with ISO 9202), quality control of palladium‑bearing alloys, and forensic or valuation analyses.
Related standards
- ISO 9202 - determination of fineness in jewellery alloys (method context).
- ISO 15093 - spectroscopy methods by difference for very high fineness (>999 ‰).
- ISO 11210 - harmonized analytical methods referenced in updates.
- ISO 11596 - sampling procedures for precious metals.
Keywords: EN ISO 11490:2023, palladium determination, gravimetry, dimethylglyoxime, jewellery, precious metals, fineness, ICP‑OES, aqua regia.
