Radioassay for β-emitters in biological materials using cerenkov radiation

Abstract

An investigation was conducted on the detection of β-emitting radionuclides in plant roots by means of Cerenkov radiation. The samples were directly radioassayed in polyethylene vials with an aqueous solution of the wavelenght shifter 7-amino-1,3-naphthalene-disulfonic acid. High efficiencies are obtained for hard β-emitters, e.g. about 60% for 86Rbuin 1 g tissue. The relatively weak β-emitter 36Cl can still be determined with an efficiency of 13 per cent in plant roots. The maximum β-energy of a nuclide must be at least 0.5 MeV for radioassay by Cerenkov radiation in biological material. Self-absorption of weak β-emitters in tissues has to be considered. The procedure described here should be applicable to other plant tissues and to animal materials. The method was tested in experiments on the kinetics of ion absorption by plant roots and earlier work in which radioactivity was determined with a gas-flow counter was confirmed.