ISO/TC 147/SC 3/WG 6 - Tritium and carbon 14

This document specifies a method by liquid scintillation counting for the determination of tritium activity concentration in samples of marine waters, surface waters, ground waters, rain waters, drinking waters or of tritiated water ([3H]H2O) in effluents. The method is not directly applicable to the analysis of organically bound tritium; its determination requires additional chemical processing of the sample (such as chemical oxidation or combustion). With suitable technical conditions, the detection limit may be as low as 1 Bq·l−1. Tritium activity concentrations below 106 Bq·l−1 can be determined without any sample dilution.

ISO 13168:2015 describes a test method for the simultaneous measurement of tritium and carbon-14 in water samples by liquid scintillation counting of a source obtained by mixing the water sample with a hydrophilic scintillation cocktail. This is considered a screening method because of the potential presence of interfering nuclides in the test sample. The method can be used for any type of environmental study or monitoring. ISO 13168:2015 is applicable to all types of waters having an activity concentration ranging from 5 Bq/l to 106 Bq/l (upper limit of the liquid scintillation counters for direct counting). For higher activity concentrations, the sample can be diluted to obtain a test sample within this range.