An emergency urine bioassay method for 241Am by extraction chromatography and liquid scintillation counting

An emergency urine bioassay method has been developed for the determination of 241Am in human urine samples. The method is based on extraction chromatographic separation of 241Am from urine on a single DGA (N, N, N', N'-tetraoctyl-diglycolamide) resin column followed by liquid scintillation counting of 241Am. The minimum detectable activity (MDA) for the method was 0.02 Bq. Considering the volume of urine sample (17.2 ml) used by the method; the MDA was 1.3 Bq l-1. Measurement accuracy (relative bias, Br) and repeatability (relative precision, SB) of the method were found to be -3.4 and 8.9%, respectively, when urine samples were spiked with 241Am (20 Bq l-1). Excellent linearity (r2 > 0.999) was established over the range of 2-200 Bq l-1. The method was also found to be robust (SB = 10.2%) against matrix effects from different urine samples. Performance of the rapid bioassay method for accuracy and repeatability were evaluated against the performance criteria for radio-bioassay (ANSI N13.30) and found to be in compliance. Considering the simplicity, excellent analytical figures of merit and fast sample turnaround time (< 1 h), it is a very promising rapid bioassay method for supporting the medical response to an emergency where internal contamination of 241Am is involved. (authors)