Determination of ³H in Biological Materials by Liquid Scintillation Counter

Abstract

Methods for measuring tritium in a biological sample were examined. A lyophilized organ material is pulverized and about 20 mg. of it is weighed into a JP No. 2 capsule or adhesive Cellophane tape vessel containing a piece of a filter paper as incineration agent, and the whole is placed in an oxygen flask. This is incinerated in oxygen atmosphere by electric sparking and the tritium oxide thereby formed is condensed with dry ice and acetone. The gas inside the oxygen flask is exchanged with nitrogen, hydrophilic scintillator is added, and the content is transferred quantitatively into a vial. Radio activity is measured with a liquid scintillation counter and the values thereby obtained are corrected by the channel ratio method. This method is applicable to the measurement of tritium in the liver, kidney spleen, heart, adrenal, muscles, and blood. Recovery rate of tritium was 96% and its standard deviation was below 1%. Scatter of measured values was examined with the same liver of a rat given vitamin E ³H-nicotinate and the standard deviation was 2.2% in this case.