This document specifies a method for the measurement of 99Tc in all types of water by inductively coupled plasma mass spectrometry (ICP-MS).
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. A filtration of the test sample is necessary.
The detection limit depends on the sample volume and the instrument used. The method described in this document, using currently available ICP-MS, has a detection limit of approximately 0,2 ng·kg-1 to 0,5 ng·kg-1 (0,1 Bq·kg-1 to 0,3 Bq·kg-1), which is much lower than the WHO criteria for safe consumption of drinking water (100 Bq·l-1)[3]. The method presented in this document is not intended for the determination of ultra-trace amount of 99Tc.
The mass concentration values in this document are expressed by sample mass unit instead of sample volume unit as it is usually the case in similar standards. The reason is that 99Tc is measured in various matrix types such as fresh water or sea water, which have significant differences in density. The mass concentration values can be easily converted to sample volume unit by measuring the sample volume. However, it increases the uncertainty on the mass concentration result.
The method described in this document is applicable in the event of an emergency situation, but not if 99mTc is present at quantities that could cause interference.
The analysis of Tc 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.