Effects of permeability of polyethylene vials in liquid scintillation counting

Abstract

The effects of the permeability of polyethylene counting vials on the liquid scintillation counting of radioactive materials and channels ratios have been examined. The count rate of toluene-soluble and water-soluble radioactive material dissolved in a suitable scintillation mixture altered by not more than 5 per cent in 4 days. The sample channels ratio altered only slightly or not at all. Changes in external standard channels ratio varied between 3 and 25 per cent in that time, depending on scintillation mixture and temperature of storage. Changes were in all cases greater if vials containing prepared samples were kept at 20°C than if they were kept at 5°C. If n-hexadecane radioactive standard was dispensed into empty polyethylene vials there was a reduction in counting efficiency related to the delay before adding scintillation mixture; the efficiency fell 5 per cent within 2 hr.