ISO 13168:2023

Overview

ISO 13168:2023 - "Water quality - Simultaneous determination of tritium and carbon 14 activities - Test method using liquid scintillation counting" defines a standardized laboratory method for measuring both tritium (3H) and carbon‑14 (14C) in water. The technique mixes a water sample with a hydrophilic scintillation cocktail and performs liquid scintillation counting (LSC) on the resulting source. ISO 13168:2023 is intended mainly as a screening method because other radionuclides can interfere; when samples are known to be free of interferences, the method provides quantitative results. The procedure applies to a wide range of waters with activity concentrations typically from 5 Bq·L⁻¹ to 10⁶ Bq·L⁻¹ (higher activities can be diluted).

Key Topics

• Principle: simultaneous detection of 3H and 14C by LSC after sample/cocktail mixing.
• Scope of applicability: supply/drinking water, rainwater, surface/ground water, marine water, cooling and industrial water, domestic and industrial wastewater.
• Sampling & storage: guidance consistent with ISO 5667 series for representative sampling and preservation.
• Reagents & equipment: hydrophilic scintillation cocktails, calibration sources, quenching agents, and LSC instruments.
• Procedure elements: sample preparation, vial preparation, counting protocol, calibration and control, measurement conditions.
• Quality metrics: instructions for interference control, decision thresholds, detection limits, combined standard uncertainty, and result expression.
• Reporting: required information for test reports and an example calculation (Annex A).
• Safety & competence: emphasizes trained personnel and standard laboratory safety practices.

Applications

ISO 13168:2023 is used by organizations involved in radiological and water quality monitoring:

• Environmental and public‑health laboratories performing routine monitoring of drinking water and environmental waters.
• Regulatory bodies assessing compliance with national or WHO guidance levels for 3H and 14C.
• Nuclear and industrial facilities monitoring effluents and cooling waters.
• Research institutions conducting environmental studies involving radionuclide transport or fate.
• Emergency response teams requiring rapid screening for tritium and carbon‑14 following incidents (with possible method adjustments for sensitivity).

Practical advantages include standardized sample handling, established calibration and uncertainty treatment (aligned with GUM/ISO 98‑3), and flexibility to adjust sample volume and counting time to meet detection requirements.

Related standards

• ISO 19361 - LSC method for beta emitters
• ISO/IEC Guide 98‑3 (GUM) - Uncertainty of measurement
• ISO 5667 series - Water sampling guidance
• ISO/IEC 17025 - Laboratory competence

Keywords: ISO 13168:2023, tritium, carbon‑14, liquid scintillation counting, water quality, radioactivity measurement, screening method, environmental monitoring, drinking water testing.