Optimization of 14C LSC measurement using CO2 absorption technique

Abstract

Abstract Liquid Scintillation Counting (LSC) is the most commonly used technique for quantification of 14C in the environmental samples. An optimization study was carried out for the analysis of 14C with the direct carbon dioxide absorption method using LSC. The absorption capacity of CO2 in varying amounts of CO2 absorber Carbo-Sorb E to Permafluor scintillation cocktail volumes is found to be 5.33 ± 0.053 mmol/mL of Carbo-Sorb E. The optimum volume ratio of Carbo-Sorb E to Permafluor scintillation cocktail is found to be 1:1 based on the minimum detection activity (MDA) values. The effect of CO2 loading in the optimized absorption mixture shows that with an increasing CO2 amount (up to saturation) there is an increase in tSIE values which is due to an increase of Compton scattering effect in the CO2 loaded samples. The region of interest (ROI) for 14C measurement is found to be 10–96 keV based on the figure of merit values and the efficiency for detecting 14C is 83.45 % in the optimized ROI window.