ISO 13162:2011 specifies the conditions for the determination of ¹⁴C activity concentration in samples of environmental water or of ¹⁴C-containing water using liquid scintillation counting.

The method is applicable to the analysis of any organic molecule soluble in water that is well mixed with the scintillation cocktail. It does not apply to micelles or "large" particles (lipids, fulvic acid, humic acid, etc.) that are inadequately mixed with the scintillation cocktail and the water. Some beta energy is lost without any excitation of the scintillation cocktail and the results are underestimated. The method is not applicable to the analysis of organically bound ¹⁴C, whose determination requires additional chemical processing (such as chemical oxidation, combustion).

It is possible to determine ¹⁴C activity concentrations below 10⁶ Bq l^-1 without any sample dilution.