Springer Online Journal Archives 1860-2000
Summary High-resolution31P NMR spectroscopy is shown to be a potentially valuable new method for monitoring the spontaneous precipitation of calcium phosphates from metastable supersaturated solutions. An apparatus capable of pH-statting the sample in a spinning 20 mm NMR sample tube is briefly described. The spontaneous precipitation of dicalcium phosphate dihydrate, CaHPO4· 2H2O, pH-statted at pH 5, is characterized by a base-uptake curve which follows the decrease in the intensity of the solution31P resonance. The precipitation of amorphous calcium phosphate at neutral pH, which exhibited an induction period of ∼ 10 min, was also studied. No evidence of NMR peaks from transient clusters or the initial colloidal solid phase has been seen.
Type of Medium: