Overview - ISO 22908:2020 (Water quality, Radium 226 & 228)
ISO 22908:2020 specifies a laboratory test method for determining activity concentrations of radium-226 (226Ra) and radium-228 (228Ra) in drinking water using chemical separation followed by liquid scintillation counting (LSC). The standard covers sampling considerations, instrument set‑up and calibration, sample preparation, separation and purification of radium, measurement, quality control, and reporting. It is suitable for routine monitoring and for rapid detection of radium contamination in emergency situations.
Key facts:
- Method detects massic activities down to 0.01 Bq/kg for 226Ra and 0.06 Bq/kg for 228Ra (for a 0.5 kg sample and 1 h counting in a low‑background LSC).
- Includes procedures for determining counting efficiency, chemical recovery, blanks, decision thresholds, detection limits and uncertainty assessment.
Key topics and technical requirements
- Principle: Chemical separation of radium from the water matrix followed by measurement with liquid scintillation counting.
- Sampling & sample handling: References ISO 5667 series for correct preservation and transport of drinking water samples.
- Instrument set‑up and calibration: Optimization of counting conditions, preparation of radium standards, and determination of counting efficiencies.
- Chemical procedures: Precipitation, purification and preparation of radium sources prior to LSC.
- Quality control: Blank measurements, QC samples with known activities, determination of chemical recovery and overall measurement uncertainty.
- Performance metrics: Calculation of massic activities at sampling date, standard uncertainty, decision threshold, detection limit and confidence limits.
- Documentation: Required elements for a comprehensive test report and informative annexes (flow chart, decay series, setup parameters, validation data).
Practical applications and who uses it
This standard is intended for:
- Environmental and public health laboratories performing regulatory drinking water monitoring.
- Water utilities verifying compliance with national guidance levels and WHO recommendations.
- Emergency response teams and radiological monitoring units needing rapid detection of radium contamination.
- Accredited testing labs seeking conformity with ISO/IEC 17025 for radionuclide analysis.
Applications include routine compliance testing, assessment of wastewater and liquid effluents (with method adaptations), and rapid screening during nuclear or radiological incidents.
Related standards and references
- ISO 5667 series (water sampling guidance, preservation and handling)
- ISO 3696 (water for analytical laboratory use)
- ISO/IEC 17025 (laboratory competence and accreditation)
- ISO/IEC Guide 98-3 (uncertainty of measurement) - referenced for uncertainty treatment
Keywords: ISO 22908:2020, radium-226, radium-228, liquid scintillation counting, water quality, drinking water testing, radium detection, detection limit, decision threshold, radiological monitoring.