Application of Low Background Liquid Scintillation Counting Method to Pharmacy:II. Variation of Endogenous ¹⁴C in Human Urine

Abstract

The intra-day, inter-day and individual variations in endogenous ¹⁴C radioactivity of human urine were studied by use of 5mL urine. The endogenous ¹⁴C radioactivity of human urine is relatively constant(approximately1.5dpm/mL urine). In order to eliminate the effect of endogenous ⁴⁰K it is of the greatest importance to count ¹⁴C signal with the optimal window. Since these variations are relatively small, we can estimate correctly the net ¹⁴C activity from the BG value of the same time zone of the day before dosing.