Patent US4335086A successfully refreshed from Google Patents.
US4335086A
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US
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Hydroxyapatite and its preparation
Assignee: Individual
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Filing: 1979-07-17
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Granted: 1982-06-15
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Expires: 1999-07-17
Abstract
Abstract Hydroxyapatite is prepared by heating an aqueous suspension of brushite without boiling at a substantially neutral pH. In this way, hydroxyapatite having rosette-shaped crystals can be prepared, having good flow rate when packed in a column or good resolution between elution peaks.
Inventors
- 👤 Michael Spencer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 06:03
CPC Classifications
C; C01; C01B; C01B25/00; C01B25/16; C01B25/26; C01B25/32; C01B25/327
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
103 words
A process for preparing hydroxyapatite, comprising the steps of (a) adding an aqueous solution of CaCl 2 to an excess of sodium phosphate to produce an aqueous suspension of brushite; (b) heating the aqueous suspension of brushite from step (a) at a temperature of between 60° and 95° C. and maintaining the pH of the heated system at from 6 to 7.5 by the addition of alkali to produce hydroxyapatite or a mixture of hydroxyapatite and octacalcium phosphate; and (c) if octacalcium phosphate is present in the product of step (b), converting the octacalcium phosphate to hydroxyapatite by the further addition of alkali.
Claim 2
Dependent Claim
103 words
A process for preparing hydroxyapatite, comprising the steps of (a) adding an aqueous solution of CaCl 2 to an excess of sodium phosphate to produce an aqueous suspension of brushite; (b) heating the aqueous suspension of brushite from step (a) at a temperature of between 60° and 95° C. and maintaining the pH of the heated system at from 6 to 7.5 by the addition of alkali to produce hydroxyapatite or a mixture of hydroxyapatite and octacalcium phosphate; and (c) if octacalcium phosphate is present in the product of step (b), converting the octacalcium phosphate to hydroxyapatite by the further addition of alkali.
Claim 3
Dependent Claim
28 words
A process according to claim 1, wherein the pH of the heated system is maintained at from 7 to 7.5, and the product is free of octacalcium phosphate.
Claim 4
Dependent Claim
19 words
A process according to claim 1 or claim 2 wherein said sodium phosphate is admixed with brushite seed particles.
Claim 5
Dependent Claim
27 words
A process according to claim 1 or claim 2 wherein the aqueous suspension of brushite which is heated in step (b) is essentially free of octacalcium phosphate.
Claim 6
Dependent Claim
17 words
A process according to claim 1 further comprising the additional step of boiling the hydroxyapatite-containing aqueous system.
Claim 7
Dependent Claim
65 words
Essentially pure hydroxyapatite characterised by the capability of allowing a flow rate of from 40 to 80 ml/hour at room temperature in a 9×75 mm bed under a pressure head of 250 mm; a molar Ca/P ratio of from 1.49 to 1.62; a weight-specific binding capacity for bovine serum albumin of at least 30 mg/g; and a tRNA elution peak of at least 0.06 molar.
Claim 8
Dependent Claim
65 words
Essentially pure hydroxyapatite characterised by the capability of allowing a flow rate of from 40 to 80 ml/hour at room temperature in a 9×75 mm bed under a pressure head of 250 mm; a molar Ca/P ratio of from 1.49 to 1.62; a weight-specific binding capacity for bovine serum albumin of at least 30 mg/g; and a tRNA elution peak of at least 0.06 molar.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-06-14 | 1985-12-14 | 1986-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-06-14 | 1989-12-14 | 1990-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-06-14 | 1993-12-14 | 1994-06-15 | $7700.00 | Window Closed / Lapsed |