A Proportional Counter for Assaying Carbon-14 and Tritium in the Effluent of a GLC Column

Abstract

A method for analyzing carbon-14 and tritium in the effluent of a GLC column has been developed in which a conventional thin-window, gas flow proportional counter of the type generally used for counting carbon-14 deposited on planchets is used to detect the radioactivity. The column effluent is passed through a combustion tube in which organic compounds are converted to carbon dioxide and hydrogen before delivering them to the counter. To minimize changes in gas composition in the counter that occur during elution of unlabeled peaks, carbon dioxide is used as carrier gas and an accessory diluting gas flow is added to the gas stream just before it enters the 50 ml detector. This resulted in improved insensitivity to the elution of unlabeled compounds while the efficiency of the detector for carbon-14 was comparable to those of other methods previously reported.