| Two solid phase extraction (SPE) systems based on novel magnetic nanoparticles (MNP) were tested for selective extraction of 90Sr for emergency radiobioassay. Poly-2-Acrylamido-2-methylpropane sulfonic acid (p-AMPS) coated MNPs were used to extract 90Sr from urine, which was eluted with 200 mM phosphate for measurement by liquid scintillation counting. The linear dynamic range was 12 Bq/L to 600 Bq/L with an overall recovery of 87% ± 10% and minimal detectable amount of 4.9 Bq/L ± 0.5 Bq/L. A 3% error with an average relative bias of 12% was found. The extraction time is 45 minutes per batch of 9 samples. The second SPE system was 4'4'5 di-tert-butyl-cyclohexano-18-crown-6 immobilized to the surface of p-acrylamide coated MNPs for the extraction of 90Sr in urine. Trapping efficiency of 90Sr was found to be 101% ± 5%. The elution efficiency using EDTA was found to be 87% ± 8%. |
