A flow-through method for scintillation counting of carbon-14 and tritium in gas-liquid chromatographic effluents

Abstract

A method for radioassay of gas-liquid chromatographic effluents by scintillation counting has been developed. A cartridge filled with anthracene crystals is used as a “flow-through” radiation detector. Upon leaving the column, the effluent is passed over hot copper oxide, which converts the organic materials to carbon dioxide and water. If tritium is to be counted, the water is reacted with hot iron to release hydrogen and tritium gases. The effluent is then passed through the anthracene cartridge. The counting rate of the cartridge is monitored continuously during the analysis by a highly efficient, low-background, scintillation counter to yield a record of eluted radioactivity that resembles the conventional mass detector record.The detector is simply constructed, easily maintained, insensitive to change in gas composition but highly sensitive to radiation. High efficiency (more than 70% for carbon-14 and 20% for tritium) is coupled with low background counting rates (ca. 15 cpm at carbon-14 settings, 50 cpm at tritium settings). The counting rate returns to this low background rate following the detection of a labeled compound.