ESR study of Gd3+ and Mn2+ ions sorbed on hydroxyapatite

Adsorption of Gd3+ and Mn2+ into hydroxyapatite (HAP (Ca5(PO4)3(OH)2)) was studied by ESR, ion chromatography and ICP-AES to investigate the U-uptake model. HAP absorbed Gd3+ via a cation exchange reaction and resulted in a signal width of 240 mT. The growth of the thermally stable Gd3+ signal in HAP was also fitted by saturation and diffusion equations. The ESR signals of Gd3+ and Mn2+ were observed overlapping the CO2− signals, however, the dose-response curves of the CO2− signal were similar to that of control HAP.