This document specifies a method for the measurement of ²¹⁰Pb in all types of waters by liquid scintillation counting (LSC).

The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample is necessary. Lead‑210 activity concentration in the environment can vary and usually ranges from 2 mBq l^-1 to 300 mBq l^{-1 [27][28]}.

Using currently available liquid scintillation counters, the limit of detection of this method for ²¹⁰Pb is generally of the order of 20 mBq l^-1 to 50 mBq l^-1, which is lower than the WHO criteria for safe consumption of drinking water (100 mBq l⁻¹).^[4][6] These values can be achieved with a counting time between 180 min and 720 min for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. The method presented in this document is not intended for the determination of an ultra-trace amount of ²¹⁰Pb.

The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency).

The method described in this document is applicable to an emergency situation.

The analysis of Pb adsorbed to suspended matter is not covered by this method.

It is the user’s responsibility to ensure the validity of this test method for the water samples tested.