A simple method for the differential measurement of 125I and 3H by liquid-scintillatin spectrometry.
1. A method is described for the differential radioactivity counting of 125I and 3H in a liquid-scintillation spectrometer without a separate gamma counter. 2. The sample was contained in a polyethylene miniature vial placed centrally in a standard 20 ml glass scintillation vial containing a tin-loaded scintillant. 3. A direct measure of the 125I radioactivity at an efficiency of 30% was then obtained by radioactivity counting in the pre-set 3H window of a scintillation spectrometer. No counts for 3H radioactivity were registered at this stage because of the barrier to the passage of the low-energy beta-particles provided by the wall of the polyethylene vial. 4. After mixing the sample and scintillant both 125I and 3H were detected at efficiencies of 73% and 29% respectively. Subtraction of the 125I contribution from the combined radioactivity count rate then gave the net 3H count.
D006801:Humans; D007457:Iodine Radioisotopes; D013051:Spectrometry, Gamma; D014316:Tritium
D007457:Iodine Radioisotopes; D014316:Tritium