Overview
ISO 18214:2024 - Jewellery and precious metals - Determination of high purity gold, silver, platinum and palladium - Difference method using SPARK‑OES defines an analytical procedure to measure high‑purity precious metals (nominal content ≥ 999 ‰) using an optical emission spectrometer excited by spark discharge. The standard specifies sample preparation, instrument requirements, calibration/standardization, quality control and result calculation where the precious‑metal content is obtained by subtracting measured impurities from 1 000 ‰.
Key topics and requirements
- Scope and principle
- Applies to high purity gold, silver, platinum, palladium (≥ 999 ‰).
- Uses a difference method: quantify impurities by SPARK‑OES then compute precious‑metal purity = 1 000 ‰ − sum(impurities).
- Equipment and reagents
- SPARK‑OES with spark excitation; typical detection limit around 1 mg/kg per impurity.
- Argon gas (≥ 99.998 % recommended), hydraulic press, milling/turning machines for surface preparation.
- Sample preparation & sampling
- Surface must be flat, smooth and contamination‑free; sampling per ISO 11596.
- Samples must cover analysis table hole and avoid overheating during sparks.
- Calibration and calibration curves
- Matrix‑specific calibration (separate for Au, Ag, Pt, Pd).
- Minimum of three calibration standards for a first‑degree function; use first‑ or second‑degree regressions.
- Certified reference materials (CRMs) recommended where possible.
- Standardization & quality control
- Use setting up samples (SUS low and SUS high) for routine standardization to correct drift.
- Quality control samples and statistical process control (SPC) to monitor instrument stability.
- Minimum three sparks per standard/sample; discard defective burn marks and re‑measure.
- Performance metrics
- Detection limit defined as three standard deviations of low SUS readings.
- Range determined by concentration span of calibration standards.
- Reporting
- Calculation, repeatability, and test report requirements are specified.
Applications and users
ISO 18214:2024 is intended for:
- Assay laboratories, precious metals refineries and minting facilities
- Jewellery quality control and hallmarking laboratories
- Third‑party testing and certification bodies
- Manufacturers and traders needing precise purity verification of high‑purity gold, silver, platinum, palladium
Practical uses include purity certification of bars/coins/jewellery, in‑process quality assurance, detection of trace impurities and support for compliance and trade documentation.
Related standards
- ISO 11596 - Sampling of precious metals and precious metal alloys (referenced for sampling procedure)
- ISO 17034 - Definition and use of certified reference materials (referenced in CRM definition)
Keywords: ISO 18214:2024, SPARK‑OES, high purity gold, high purity silver, platinum, palladium, difference method, precious metals analysis, calibration, standardization, quality control.
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