ISO 11490:2023

Overview

ISO 11490:2023 - Jewellery and precious metals - Determination of palladium - Gravimetry using dimethylglyoxime specifies a gravimetric analytical method for measuring palladium content in homogeneous precious‑metal materials. The method is optimized for samples with palladium content preferably between 50 and 999 ‰ (parts per thousand) by mass. Palladium above 999 ‰ is determined by spectroscopy by difference (e.g. ISO 15093). ISO 11490:2023 is also recommended for fineness determination in jewellery alloys covered by ISO 9202.

Key topics and technical requirements

• Principle: dissolve the sample in aqua regia, precipitate palladium as a dimethylglyoxime complex, calcine to metallic palladium (“palladium foam”) and weigh gravimetrically.
• Sample scope: homogeneous alloys and precious‑metal materials; preliminary composition check (e.g., XRF) recommended when composition is unknown.
• Treatment for silver-bearing samples: separate Ag as silver chloride (AgCl) prior to palladium precipitation.
• Reagents and equipment (examples specified):
  • Concentrated HCl (≈30–37 %) and HNO3 (≈65–70 %), diluted solutions, aqua regia
  • Dimethylglyoxime (aqueous and ethanolic saturated solutions)
  • Muffle furnace (≈800 °C ± 50 °C), reducing and inert gases for calcination, porcelain crucibles, ash‑free filter paper, analytical balance (0.01 mg)
  • ICP‑OES for trace‑element analysis of coprecipitated alloying elements
• Calcination and reduction: control oxidation during calcination (use of reducing gas or post‑reduction may be required) and determine coprecipitated elements in the dissolved palladium residue to apply corrections.
• Performance: duplicate determinations should agree within ±3 ‰ (repeatability criterion).

Practical applications and users

• Primary users:
  • Jewellery and precious‑metals testing laboratories
  • Assayers and quality control teams in jewellery manufacturing
  • Precious‑metal refiners and analytical services verifying fineness and alloy composition
• Typical applications:
  • Determination of palladium content in white gold and palladium alloys
  • Routine fineness certification and compliance testing for hallmarks
  • Reference/verification method where gravimetric accuracy is required or to validate spectroscopic methods

Related standards

• ISO 9202 - jewellery alloy fineness (related application)
• ISO 15093 - spectroscopy by difference for high palladium fineness
• ISO 11210 - harmonization of related gravimetric methods
• ISO 11596 - sampling procedures for precious metals

Note: Follow laboratory safety procedures when handling aqua regia and strong acids. For full procedural detail, acceptance criteria and reporting requirements consult the full ISO 11490:2023 document.