Determination of rare earth elements, uranium and thorium in apatite minerals by inductively coupled plasma-mass spectrometry

Determination and distribution of 18 elements such as rare earth elements (REE), uranium and thorium in apatite minerals were examined using inductively coupled plasma-mass spectrometry. The sample solution (1 mg/ml) which were prepared with hot concentrated nitric acid were directly injected into the plasma. REE, uranium and thorium contents in the apatite were determined by a calibration curve method. However,the intensity of thorium decreased by calcium phosphate in macro-component. Therefore, thorium was separated from these calcium phosphate by solvent extraction with 0.1 mol/dm(3) 3-Phenyl-4-benzoyl-5-isoxazolone-DIBK system. DIBK phase was evaporated by heating, dried and ashed with concentrated nitric and perchloric acids. After allowing cooling, 0.1 mol/dm(3) nitric acids was added to dissolve any precipitate. The REE,uranium and thorium content in apatite minerals from USA, China and Jordan were found to be (0.24 similar to 172), (9.69 similar to 111), (0.7 similar to 7.95) ppm, respectively. It was found that lanthanoid in apatite minerals following the Oddo and Harkins law.