Homogeneity assessment for grass samples used for organically bound tritium proficiency test

The paper presents homogeneity check for dried grass batch to be used in an inter-comparison exercise. When carrying out an inter-comparison exercise, the organizer must guarantee that the unsatisfactory result will not be imputed to the sample and sample's changeability. Therefore, in an inter-comparison exercise must carry on the homogeneity testing. In our study, the homogeneity was checked for two parameters, the hydrogen percentage (%H) and the organically bound tritium (OBT) activity concentration. Ten subsamples of 50g from bulk material were chosen using a stratified random selection. Two replicates from each package were analyzed for hydrogen content and OBT analysis. The homogeneity parameters were evaluated according to ISO 13528:2015. The two checked properties confirm that the batch of dried grass is sufficiently homogenous.