Chemistry of inorganic compounds – Phosphorus or compound thereof – Oxygen containing
Patent
1986-07-30
1987-12-08
Heller, Gregory A.
Chemistry of inorganic compounds
Phosphorus or compound thereof
Oxygen containing
423305, 423309, 423311, C01B 1516, C01B 2526
Patent
active
047117699
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a calcium-phosphorus-apatite, a process for preparing the same, and a chromatographic packing material consisting of the same. More specifically, the present invention relates to a process for preparing a calcium-phosphorus-apatite having a controlled Ca/P ratio according to a method involving fast thermal decomposition of atomized solution.
The calcium-phosphorus-apatite of the present invention provides a spherical hydroxyapatite suitable as a packing material for high-performance liquid chromatography and an apatite of submicrons in size, suitable as a powder of raw material for bioceramics.
BACKGROUND ART
Calcium-phosphorus-apatites have a peculiar performance as adsorbents for biopolymers, fluorine ions, heavy metal ions, etc. They have recently been regarded as useful as a chromatographic packing material for separation of proteins and enzymes with utilization of bioaffinities thereof. They have also attracted attention as substances capable of being used in bioceramic materials for artificial bones and teeth.
Processes for preparation of these apatites have been known for a long time. According to a rough classification, however, the following processes can be exemplified.
(1) Processes involving direct precipitation with ions in an aqueous solution, which are called wet synthesis processes.
A. Tiselius et al. developed a hydroxyapatite preparation technique according to the wet precipitation reaction process [Arch. Biochem. Biophys. 65, 132-155 (1956)]. Moreno et al. presented the conditions for synthesis of a hydroxyapatite with a Ca/P ratio of 1.67 [E. C. Moreno et al., J. Res. Natl. Bur. Stand. 72 A(6), 773-82 (1968)]. The results of an experiment following the above-mentioned conditions by Larsen et al. were reported [S. Larsen et al., Experientia 27 (4), 483-85 (1971)].
In these wet synthesis processes, it is difficult to consistently obtain a precipitate having a composition with the ratio of formulation, due to a very large number of factors, including the kinds and concentrations of raw material salts, the procedure and rate of mixing, and the pH adjustment in the step of mixing an aqueous solution of a calcium salt with an aqueous solution of a phosphorus compound to form the precipitate according to a direct ionic reaction for crystallization into an apatite. Therefore, a serious difficulty is encountered in controlling the atomic ratio Ca/P of calcium and phosphorus and the physicochemical properties of the formed powder with good repeatability. Moreover, many steps involving filtration, washing, drying, and pulverization of the precipitate are needed together with many apparatuses therefor, and the operations require much skill, thus presenting a number of difficulties.
(2) Processes involving a solid diffusion reaction, which are called dry synthesis processes.
These processes are suitable for synthesis of hydroxyapatite having a stoichiometrical composition, which is hard to prepare according to any process as mentioned in (1). Fowler synthesized hydroxyapatites of alkaline earth metal according to a solid reaction of a calcium, strontium, or barium salt of pyrophosphoric acid or carboxylic acid [B. O. Fowler, Inorg. Chem. 13 (1), 207-14 (1974)]. Since the reaction according to the dry synthesis process must be continued at high temperature for a long period of time, however, large energy is disadvantageously consumed. Further, a difficulty in obtaining a homogeneous composition ensues from the solid-solid reaction.
(3) Processes involving a high pressure reaction, which are called hydrothermal synthesis processes, and which are performed mainly for the purpose of obtaining large crystals.
Problems such as use of expensive apparatus and complicated operations are involved in these hydrothermal processes because the reaction is performed under high pressure.
Columns packed with hydroxyapatite have recently been marketed. This has enabled biopolymers of 10.sup.5 daltons or more to be separated and purified, which was previously imposs
REFERENCES:
patent: 3023083 (1962-02-01), Rodis et al.
patent: 4481175 (1984-11-01), Iino et al.
Inoue Senya
Ono Akira
Heller Gregory A.
Kanto Kagaku Kabushiki Kaisha
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