Selective extraction of 90Sr in urine using 4′4(5)di-tert-butyl dicyclohexano-18-crown-6 ether immobilized on polyacrylamide-coated magnetic nanoparticles

4'4 ''(5 '')di-tert-butyl dicyclohexano-18-crown-6 ether was immobilized onto the surface of iron oxide magnetic nanoparticles coated with divinylbenzene-crosslinked polyacrylamide. The coated magnetic nanoparticles were successful in selectively extracting Sr-90 from human urine samples, as confirmed by the liquid scintillation counting spectra. This method offers excellent repeatability for Sr-90 in urine bioassay, with a relative precision of 8 % when five urine samples collected from different donors were spiked with1.58 Bq of Sr-90 and analyzed.