A procedure for the Cherenkov counting of high energy β and γ emitting radionuclides in coloured plant extracts.

Elimination of count rate variations caused by the absorption of Cherenkov radiation by pigments in coloured solutions was achieved by placing these solutions in opaque walled cylinders immersed in colourless liquids contained in standard counting vials. Good counting efficiencies for a range of β and γ emitting radionuclides were obtained by selecting colourless liquids with high refractive index.