New developments for the direct CO₂ absorption method for radiocarbon analysis

A method for analysis of radiocarbon using direct absorption into an alkaline organic amine, and subsequent LSC, was introduced by Qureshi et al. (1989). This paper describes several modifications to that original idea by development of a recirculating closed-system and use of bladder system to store and deliver CO₂. The modifications have increased the precision and useability of the method which ensures saturation of the Carbosorb and allows up to 5 samples to be prepared for counting per day per extraction line. Organic samples can also be prepared for LSC by using a Parr bomb which is much more efficient than conventional combustion in a stream of oxygen. Overall, the method has slightly lower precision than the benzene method but, in many instances, counting statistics are much less than the overall uncertainty contributed by inter- and intra-sample variability. Therefore, for applications in many instances where radiocarbon is used as a dating tool or as a tracer, the Carbosorb method now provides a rapid and less expensive alternative.