Rapid determination of tritium and carbon-14 in urine samples using a combustion technique

Abstract

Traditionally in bioassay monitoring, 3H determinations in urine have been performed using either direct counting (with or without sample decolourisation) or distillation whilst 14C has been determined on separate sub-samples following chemical isolation of the carbon from samples. Although these techniques are relatively straightforward they do not permit simultaneous determination of 3H/14C. For 3H, direct counting can be significantly affected by variations in sample composition/colour resulting in varying degrees of sample quench, does not distinguish between aqueous/organically-bound 3H and is limited to small sample sizes. This study describes the use of purpose built multi-tube combustion furnace for the simultaneous extraction and determination of 3H and 14C. The technique is insensitive to sample composition and can be adapted to measure Tritiated water (HTO) and organically bound tritium separately. The development of a multi-tube system with integrated cool-down facility permits rapid throughput of high sample numbers and has been proven effective in decommissioning waste characterisation. In addition, the furnace-based technique is capable of processing larger sample sizes, increasing analytical sensitivity and accuracy of dose assessment.