RESUMO
Objective:To improve the analytical method of radionuclide 14C, and estimate the internal dose caused by 14C to human, in order to protect the health of workers and the public in workplaces involving potential 14C exposure. Methods:Urine samples were pretreated by wet oxidation. In the analysis, potassium persulfate was used as an oxidant to decompose urea into carbon dioxide, which was absorbed by 1 mol/L sodium hydroxide, and the absorption solution was converted into calcium carbonate precipitation. After calcium carbonate powder was prepared into sample source by suspension method, the low background liquid scintillation counter was applied to measure the radioactivity, which can be used for calculating the result.Results:The reaction time optimized by using carbamide as carrier was 1 h. For 80 ml urine, the amount of potassium persulfate used was 10 g. The method recovery rate reached about 100%. Four real urine samples were tested using the optimized method, and the result of activity concentration 14C was 0.32, 0.60, 0.86 and 0.74 Bq/L, respectively. Conclusions:The optimized method had good stability, high accuracy and stable experimental result, which could meet the needs of routine radiological detection. The establishment of a quantitative method for 14C in urine sample has improved the methodological system for 14C monitoring.