Overview
ISO 23655-2:2022 - "Water quality - Nickel-59 and nickel-63 - Part 2: Test method using ICP‑MS" specifies a standardized procedure for determining the activity concentration of the radionuclides nickel‑59 (59Ni) and nickel‑63 (63Ni) in all types of water using inductively coupled plasma mass spectrometry (ICP‑MS). The method can achieve typical measurement capabilities of ~300 mBq·L⁻¹ for 59Ni and ~200 Bq·L⁻¹ for 63Ni with a 1.0 L sample volume. Performance depends on laboratory measurement regimes, stable‑nickel content, instrument background and counting efficiency.
Key topics and technical requirements
- Measurement principle: ICP‑MS determination of 59Ni and 63Ni activity concentrations.
- Performance indicators: Detection capability examples (59Ni 300 mBq·L⁻¹; 63Ni 200 Bq·L⁻¹ with 1 L sample) and options to handle higher activities (dilution or smaller aliquots).
- Sample preparation: Guidance on sampling, sample handling and preparation consistent with the ISO 5667 series. Annex A covers isolation and purification of nickel.
- ICP‑MS setup: Instrument calibration, mass bias correction, background signal management and calibration procedures.
- Chemical separation: Procedures to address interferences (e.g., iron) and reduce stable‑nickel effects that influence detection limits.
- Quality control: Procedures for recovery assessment, uncertainty estimation, characteristic limits, and reporting.
- Safety and competence: Tests must be performed by trained personnel; laboratories are responsible for verifying method suitability for given water matrices.
Practical applications
- Environmental monitoring of surface water, groundwater and seawater for anthropogenic and natural radionuclides.
- Routine monitoring of drinking water and wastewater to demonstrate compliance with national guidance levels and regulatory limits.
- Monitoring liquid effluents and radioactive waste streams from nuclear facilities and industries handling radioactive materials.
- Emergency and post‑incident assessments (e.g., to verify guidance levels after radiological events).
Who should use this standard
- Accredited analytical laboratories performing radionuclide measurements.
- Environmental and public‑health authorities, water utilities and regulators.
- Nuclear industry laboratories and operators managing liquid effluents.
- Research institutions studying radionuclide behavior in aquatic environments.
Related standards and references
Key normative references used in ISO 23655‑2 include ISO 5667 (sampling), ISO 3696 (water for analytical use), ISO 17294‑2 / ISO 11885 (ICP‑MS/ICP‑OES guidance) and ISO/IEC 17025 (laboratory competence). ISO 23655‑2 is part of the wider ISO 23655 series on nickel radionuclide measurement.
Keywords: ISO 23655‑2, nickel‑59, nickel‑63, ICP‑MS, water quality, radionuclide measurement, detection limit, sampling, laboratory accreditation, environmental monitoring.