Cation exchange polymer particles have been synthesized for urinalysis to monitor levels of strontium-90 (Sr-90) exposure in humans. Two techniques were utilized in the incorporation of a Sr2+ selective chelating agent, di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6). The ion imprinting technique involved entrapment of DtBuCH18C6 during the formation of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) polymer particles. In the surface immobilization technique, adsorption of DtBuCH18C6 onto the surface of AMPS polymer particles was assisted by a molecular modifier. Ethylene glycol dimethacrylate (EGDMA) and divinylbenzene (DVB) were evaluated as cross-linking agents to provide better support for DtBuCH18C6. These polymer particles were characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Radiometric binding assays demonstrated that surface immobilization, in comparison to matrix imprinting, achieved greater Sr2+ uptake. Application of the surface immobilized particles in urinalysis was successful, attaining 86 +/- 2% Sr-90 uptake at pH 9. (C) 2012 Elsevier Ltd. All rights reserved.