ISO 4722-2:2024

Overview

ISO 4722-2:2024 - Water Quality - Thorium 232 - Part 2: Test Method using ICP-MS establishes a standardized procedure for determining thorium-232 (232Th) concentrations in various water types using inductively coupled plasma mass spectrometry (ICP-MS). This international standard supports consistent, reliable results, crucial for environmental monitoring and compliance with health and regulatory guidelines associated with water quality and radioactivity.

This method is applicable to a range of water samples, including:

• Drinking water
• Rainwater
• Surface and ground water
• Marine water
• Industrial and domestic wastewater
• Cooling and process water

It is suitable for routine monitoring, regulatory compliance, emergency situations, and research purposes involving radiological water analysis.

Key Topics

Scope of Measurement

• ISO 4722-2:2024 details the ICP-MS technique for measuring 232Th in filtered water samples.
• The standard outlines the procedure for converting measured mass concentrations to activity concentrations.
• Analytical range: Activity concentrations between approximately 2 mBq·L⁻¹ and 5 Bq·L⁻¹; higher concentrations may be measured after suitable dilution.
• The method’s limit of detection (~2 mBq·L⁻¹) is well below WHO guidelines for drinking water.

Sample Preparation and Handling

• Water samples must be filtered to remove suspended matter before analysis (analysis of particulates is not included under this method).
• All steps require clean laboratory protocols to avoid contamination, using ultrapure water and high-purity reagents.
• Proper acidification and storage are mandated to preserve sample integrity during transport.

Analytical Process

• Utilizes ICP-MS for high sensitivity and selectivity.
• Special attention to chemical interferences, particularly isobaric and polyatomic species, is necessary.
• Internal standards and chemical tracers are used for correction of recovery, matrix effects, and measurement bias.
• The method includes robust calibration protocols and requires regular background checks and instrument verification.

Quality Assurance

• Laboratories must demonstrate measurement competence (e.g., ISO/IEC 17025).
• Regular use of control and blank samples, as well as participation in inter-laboratory comparisons, is recommended.
• Written reports should include all relevant sample, calibration, and measurement details, as per standard requirements.

Applications

The ISO 4722-2:2024 standard provides practical value across multiple sectors:

• Drinking Water Safety: Supports regulatory authorities and water suppliers in confirming compliance with national and WHO guidance for radionuclide concentrations.
• Environmental Monitoring: Enables governmental and research organizations to monitor natural water bodies for radioactive contamination from both natural and anthropogenic sources.
• Industrial Compliance: Facilities that discharge water (e.g., nuclear plants, mining operations) can use the method to ensure emissions meet environmental standards.
• Emergency Response: Reliable for use during radiological incidents affecting water resources, ensuring rapid and accurate assessment.
• Research: Facilitates academic and commercial research into environmental radioactivity and water treatment technologies.

Related Standards

The effective application of ISO 4722-2:2024 depends on a suite of supporting standards, including:

• ISO/IEC Guide 98-3: Uncertainty of measurement - Guide to the expression of uncertainty in measurement
• ISO 5667 Series:
  • ISO 5667-1: Water sampling design and techniques
  • ISO 5667-3: Preservation and handling of water samples
  • ISO 5667-10: Guidance on sampling of wastewater
• ISO/IEC 17025: General requirements for the competence of testing and calibration laboratories
• ISO 17294 Series:
  • ISO 17294-1: General guidelines for ICP-MS in water analysis
  • ISO 17294-2: Determination of selected elements by ICP-MS
• ISO 80000-10: Quantities and units for atomic and nuclear physics

By adhering to ISO 4722-2:2024, laboratories, regulatory authorities, and industry stakeholders can ensure accurate, reproducible results in thorium-232 water analysis, enhancing public and environmental health protection.

Keywords: ISO 4722-2, water quality, thorium-232, ICP-MS, radioactive analysis, environmental monitoring, drinking water standard, radiological emergency, water testing, international standard.