A survey on uncertainty in bioassay measurements carried out within the OMINEX project

One of the topics covered by the project OMINEX (Optimisation of Monitoring for Internal Exposure) was to look at the bioassay measurements performed in the European laboratories. Questionnaires on bioassay measurements by alpha spectrometry or ICP-MS were sent to European Laboratories. The main objective was to collect information from laboratories on analytical procedures and on the uncertainties associated with bioassay results. Alpha spectrometry is the technique most used for the determination of alpha emitters such as actinides in biological samples (urine and faeces). ICP-MS is not yet used for routine measurements of actinides in biological samples, but is very sensitive for measurements of long lived radionuclides. The different parameters influencing the uncertainties on the results and the MDA have been investigated. Optimal conditions to achieve low results’ uncertainties and low MDA, for the measurements of actinides in biological samples are given for alpha spectrometry and ICP-MS.