A rapid bioassay method for the determination of 90Sr in human urine sample

A rapid bioassay method has been developed for the determination of 90Sr in human urine samples. The method is based on on-cartridge decolorisation of urine sample, separation of 90Y from 90Sr on an anion exchange resin column and by determination of 90Sr using a liquid scintillation analyser (LSA). Separation of 90Y from 90Sr was achieved through selective complexation of yttrium with phosphate and subsequent retention of the anionic yttrium phosphate species on anion exchange resin. A total recovery of 97 ± 2% was obtained for strontium with three washes. The minimum detectable activity for the method was 0.2 Bq or 40 Bq l-1. Measurement accuracy (relative bias, Br) and repeatability (relative precision, SB) of the method for the determination of 90Sr were found to be -1 and 4.7%, respectively. Excellent linearity (r2 > 0.999) was established over an activity range from 3.25 x 102 to 3.25 x 104 Bq l-1. The method was also found to be very robust (SB < 5%) against the matrix effect from different urine samples. Performance of the rapid bioassay method for sensitivity, accuracy and repeatability evaluated against the performance criteria for radio-bioassay (ANSI N13.30) was found to be in compliant. Considering the simplicity, excellent analytical figures of merit, fast sample turnaround time (< 1 h) and cost efficiency (< 30 USD per sample) of the developed method, it is very promising as a rapid bioassay method for supporting the medical response to an emergency where internal contamination of 90Sr is involved. (authors)