Overview
ISO 13165-3:2024 - Water quality - Radium-226 - Part 3: Test method using coprecipitation and gamma‑ray spectrometry specifies a laboratory method to measure radium‑226 (226Ra) activity concentration in all types of water. The method uses coprecipitation to concentrate soluble radium from sample volumes of up to 100 L, followed by high‑resolution gamma‑ray spectrometry for quantification. It is suitable for measuring soluble 226Ra above about 0.002 Bq·L−1, with typical detection limits for 1–5 L samples in the range 0.00040 to 0.002 Bq·L−1. For samples under 1 L, direct gamma spectrometry per ISO 10703 is possible but has a higher detection limit.
Key topics and technical requirements
- Scope and applicability: All water types (surface, ground, drinking, seawater); adaptable to other naturally occurring radium isotopes (223Ra, 224Ra, 228Ra) if ingrowth times are considered.
- Principle: Coprecipitation of radium from water to produce a measurable counting source, followed by gamma‑ray spectrometric measurement (see links to ISO 20042 and ISO 10703).
- Sample volumes and detection limits: Up to 100 L sample volume; soluble 226Ra > 0.002 Bq·L−1 target; typical 1–5 L detection limits 0.00040–0.002 Bq·L−1.
- Procedure elements: Blank preparation, sample preparation, and counting procedures (clause structure in the standard).
- Quality assurance / quality control: Requirements for method verification, demonstration of analyst capability, handling interferences, and instrument performance checks.
- Data reporting and uncertainty: Rules for expressing results, estimating standard uncertainties, decision thresholds, detection limits and coverage intervals (referencing ISO 11929 series), and corrections for background and contributions from other radionuclides.
- Sampling and handling: References to ISO 5667‑3 for preservation and handling of water samples; transportation and storage considerations are covered.
Practical applications and users
- Who uses it: Environmental laboratories, public health authorities, water utilities, mining and mineral-processing laboratories, regulatory agencies, and research institutions monitoring radionuclides in water.
- Typical applications:
- Routine monitoring of drinking water and source waters for regulatory compliance and public health (WHO guidance referenced).
- Environmental surveillance around nuclear, mining, oil & gas or phosphate fertilizer sites.
- Emergency response sampling where lower detection limits and reliable results are needed.
- Research on radium geochemical behavior and isotope partitioning in aquatic systems.
Related standards
- ISO 20042 (coprecipitation/gamma procedures context)
- ISO 10703 (direct gamma‑ray spectrometry for small-volume samples)
- ISO 11929 (characteristic limits: decision threshold, detection limit)
- ISO 5667‑3 (sampling preservation/handling)
- ISO/IEC 17025 (laboratory competence)
Keywords: ISO 13165-3:2024, radium-226, water quality, coprecipitation, gamma‑ray spectrometry, detection limit, water monitoring, radionuclide analysis.