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Article: Solubility of hydroxyapatite by solid titration at pH 3-4

TitleSolubility of hydroxyapatite by solid titration at pH 3-4
Authors
KeywordsHydroxyapatite
Solid titration
Solubility
Issue Date2007
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/archoralbio
Citation
Archives Of Oral Biology, 2007, v. 52 n. 7, p. 618-624 How to Cite?
AbstractObjectives: The solubility isotherm (S) of hydroxyapatite (HAp) is of fundamental importance to saliva chemistry, dental caries and related contexts. It has previously been shown that the locus of the S[HAp] is substantially lower than is commonly reported, and of different slope, probably due to HAps incongruent dissolution. The aim of the present study was to determine the S[HAp] over a wider pH range and to identify the precipitate formed at equilibrium in HAp solid titration. Methods: The solid titration technique of Leung and Darvell (Leung VW-H, Darvell BW. Calcium-phosphate system in saliva-like media. J Chem Soc Faraday Trans 1991;87(11):1759-64.) was used to investigate the solubility behaviour of HAp at 37.0 ± 0.1 °C in 100 mM aqueous KCl. The pH range studied overlapped that of earlier work from pH 3.6 to 5.2, for a reproducibility check and validation, and extended to pH ∼2.9. XRD and EDX were used to identify the precipitates. SEM and TEM were used to observe the morphology. Results: The previous S[HAp] reported by Chen et al. (Chen Z-F, Darvell BW, Leung VW-H. Hydroxyapatite solubility in simple inorganic solutions. Arch Oral Biol 2004;49(5):359-67.) was reconfirmed. An abrupt change of slope of S[HAp] was detected at pH ∼3.9. No other phase than HAp was found at pH 3.2, 3.6 and 4.1. In particular, brushite (dicalcium phosphate dihydrate) was not detected, even below pH 3.9, where instead calcium-deficient HAp was formed. Conclusion: The solid titration method was reconfirmed as reproducible and to yield HAp from pH 2.9 to 5.2. The expected brushite did not appear, but rather a stable calcium-deficient HAp was consistently formed. The chemistry of calcium phosphates needs to be reevaluated. © 2006 Elsevier Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/143147
ISSN
2015 Impact Factor: 1.733
2015 SCImago Journal Rankings: 0.713
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorPan, HBen_HK
dc.contributor.authorDarvell, BWen_HK
dc.date.accessioned2011-11-02T03:06:37Z-
dc.date.available2011-11-02T03:06:37Z-
dc.date.issued2007en_HK
dc.identifier.citationArchives Of Oral Biology, 2007, v. 52 n. 7, p. 618-624en_HK
dc.identifier.issn0003-9969en_HK
dc.identifier.urihttp://hdl.handle.net/10722/143147-
dc.description.abstractObjectives: The solubility isotherm (S) of hydroxyapatite (HAp) is of fundamental importance to saliva chemistry, dental caries and related contexts. It has previously been shown that the locus of the S[HAp] is substantially lower than is commonly reported, and of different slope, probably due to HAps incongruent dissolution. The aim of the present study was to determine the S[HAp] over a wider pH range and to identify the precipitate formed at equilibrium in HAp solid titration. Methods: The solid titration technique of Leung and Darvell (Leung VW-H, Darvell BW. Calcium-phosphate system in saliva-like media. J Chem Soc Faraday Trans 1991;87(11):1759-64.) was used to investigate the solubility behaviour of HAp at 37.0 ± 0.1 °C in 100 mM aqueous KCl. The pH range studied overlapped that of earlier work from pH 3.6 to 5.2, for a reproducibility check and validation, and extended to pH ∼2.9. XRD and EDX were used to identify the precipitates. SEM and TEM were used to observe the morphology. Results: The previous S[HAp] reported by Chen et al. (Chen Z-F, Darvell BW, Leung VW-H. Hydroxyapatite solubility in simple inorganic solutions. Arch Oral Biol 2004;49(5):359-67.) was reconfirmed. An abrupt change of slope of S[HAp] was detected at pH ∼3.9. No other phase than HAp was found at pH 3.2, 3.6 and 4.1. In particular, brushite (dicalcium phosphate dihydrate) was not detected, even below pH 3.9, where instead calcium-deficient HAp was formed. Conclusion: The solid titration method was reconfirmed as reproducible and to yield HAp from pH 2.9 to 5.2. The expected brushite did not appear, but rather a stable calcium-deficient HAp was consistently formed. The chemistry of calcium phosphates needs to be reevaluated. © 2006 Elsevier Ltd. All rights reserved.en_HK
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/archoralbioen_HK
dc.relation.ispartofArchives of Oral Biologyen_HK
dc.subjectHydroxyapatiteen_HK
dc.subjectSolid titrationen_HK
dc.subjectSolubilityen_HK
dc.titleSolubility of hydroxyapatite by solid titration at pH 3-4en_HK
dc.typeArticleen_HK
dc.identifier.emailPan, HB: haobo@hku.hken_HK
dc.identifier.emailDarvell, BW: b.w.darvell@hku.hken_HK
dc.identifier.authorityPan, HB=rp01564en_HK
dc.identifier.authorityDarvell, BW=rp00007en_HK
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.archoralbio.2006.12.007en_HK
dc.identifier.pmid17240349-
dc.identifier.scopuseid_2-s2.0-34247606617en_HK
dc.identifier.hkuros163524-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-34247606617&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume52en_HK
dc.identifier.issue7en_HK
dc.identifier.spage618en_HK
dc.identifier.epage624en_HK
dc.identifier.isiWOS:000247120700003-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridPan, HB=7403295092en_HK
dc.identifier.scopusauthoridDarvell, BW=7005953926en_HK

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