Surface labelling and its use for radioisotopic labelling of solid granular substances

Direct irradiation in the labelling of solid particles of the substance does not yield an acceptable solution, therefore solid particles are labelled by the so-called surface labelling technique. This is characterized by the efficiency of precipitation, homogeneity of the activity and its adhesion to the grains. Reduction from solution or colloid adhesion of 198Au radioisotope proved to be the most favourable method. After discussing and comparing methods and results of the labelling techniques, some case studies are presented. (author) 9 refs.; 2 tabs