A plastic scintillator method for the radioassay of H 3- and C 14-labelled ompounds on filter paper

Abstract

A simple and efficient technique for the radioassay of H 3- and C 14-labelled ompounds on filter paper is described. The technique onsists in laying a paper tissue soaked in a solution of plastic scintillator in benzene at a oncentration of ∼200 g/l, and placed onto each side of the filter paper supporting the activity. The sample is then held for a few minutes in benzene vapour to prevent premature evaporation of the solvent and dried at a temperature of about 60°C. The dried sample is then placed vertically in an otherwise empty ounting vial and ounted in a onventional Tri-Carb liquid scintillation spectrometer. Efficiencies of about 20 per cent were obtained for tritiated non-polar ompounds, and of about 10 per cent for tritiated polar ompounds. The use of dioxan as a solvent for the plastic scintillator appears to be advantageous when ounting tritiated polar ompounds on filter paper. The assay of C 14-labelled ompounds on filter paper gave exceptionally good results using this technique.