NF ISO 4685, M60-844 (01/2024)

This document specifies methods for determining the concentration of 226Ra by inductively coupled plasma mass spectrometry (ICP-MS). On the basis of the mass concentration obtained, the activity concentration can be calculated. The method is applicable to samples of drinking water, rainwater, surface water and groundwater, once collection, sampling and sample preparation for testing have been carried out properly. and due form. The detection limit depends on the sample volume, the instrument used, the instrument background, the sensitivity of the instrument, the acquisition time and the chemical treatment efficiency. The detection limit of the method described in this document, with currently available equipment, is approximately 10 mBq·l-1, i.e. a value at which drinking water consumption is considered as very safe according to WHO criteria (1 Bq·l-1). This method covers the measurement of 226Ra in water at activity concentration levels between 0.001 Bq·l-1 and 100 Bq·l-1. It is possible to measure, after dilution, samples with an activity concentration greater than the upper limit of 1 Bq·l-1. The method described in this document is applicable during an emergency situation. In this method, it is necessary to filter the test sample. The analysis of 226Ra adsorbed on suspended solids is not covered by this method. The analysis of the insoluble fraction requires a mineralization step not covered by this document. If necessary, the measurement is carried out on the different phases obtained. It is the user's responsibility to ensure the validity of this test method for the water samples tested.
(Automatic translation from French)