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 90Sr from human urine samples, as confirmed by the liquid scintillation counting spectra. This method offers excellent repeatability for 90Sr in urine bioassay, with a relative precision of 8 % when five urine samples collected from different donors were spiked with1.58 Bq of 90Sr and analyzed.