Tritium assay by combustion with a novel oxygen train and liquid scintillation techniques

A method has been reported for the analysis of tritium in biological samples weighing between 0.1 and 2 gm. This method, offering advantages over previous methods, employs a combustion tube of new design in an oxygen train. The tube design permits the oxidation and simultaneous collection of tritiated water in 10 min for samples weighing 600 to 800 mg. Coupling the method with the channels ratio method of liquid scintillation counting allows the procedure to be independent of sample weight and dryness. Samples of low activity (500 dpm) or series of samples varying in radioactivity may be assayed accurately because of the low memory effect of the train. Criteria used to assess the accuracy of the method were the percentage recoveries of tritium from groups of samples varying in weight, radioactivity, biological source, and chemical form of the tritium added. The recoveries and standard deviations of these different groups ranged from 99.4 to 96.6 and 1.2 to 3.5%, respectively, thus indicating the accuracy of the method from the analysis of tritium in biological samples and its suitability for samples of various weights and activities.