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Phosphate Dihydrate (phosphate + dihydrate)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Determination of neutral carbohydrates by CZE with direct UV detection

ELECTROPHORESIS, Issue 17 2007
Stella Rovio
Abstract A new CZE method relying on in-capillary reaction and direct UV detection at the wavelength 270,nm is presented for the simultaneous separation of the neutral carbohydrates xylitol, D -(,)-mannitol, sucrose, D -(+)-fucose, D -(+)-cellobiose, D -(+)-galactose, D -(+)-glucose, L -rhamnose, D -(+)-mannose, D -(,)-arabinose, D -(+)-xylose, and D -(,)-ribose. The alkaline electrolyte solution was prepared of 130,mM sodium hydroxide and 36,mM disodium hydrogen phosphate dihydrate. Separation of the sample mixture was achieved within 35,min. Calibration plots were linear in the range of 0.05,3,mM. Reproducibility of migration times was between 0.3 and 1.1%, and the detection limits for the analytes were 0.02 and 0.05,mM. The optimized method was applied for the determination of neutral monosaccharides in lemon, pineapple, and orange juices and a cognac sample. The methodology is fast since no other sample preparation except dilution is required. [source]

Evaluation of a rotary tablet press simulator as a tool for the characterization of compaction properties of pharmaceutical products

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2010
F. Michaut
Abstract The Stylcam 100R, a rotary press simulator, was designed to simulate speed profiles of rotary tablet presses. Such a simulator was qualified by numerous laboratories and, actually, its ability to be used for studying the behaviour of powders under pressure should be examined. Then, the purpose of this work was to investigate the performances of the Stylcam 100R for characterizing the compaction behaviour and the tabletting properties of pharmaceutical powders. The compressibility of three pharmaceutical excipients (microcrystalline cellulose, dicalcium phosphate dihydrate and ,-lactose monohydrate) was studied. Four compression speeds were used on the compaction simulator. Force,displacement cycles were associated with two energy parameters, the specific total energy (Estot) and the specific expansion energy (Esexp). The mean yield pressure was calculated from Heckel's plots obtained with the in-die method. The diametral tensile strength of compacts was measured in order to evaluate mechanical properties. To evaluate the accuracy of all these parameters, a comparative study was carried out on an eccentric instrumented press. The values of energy parameters and tensile strengths of tablets are close between the eccentric press and the compaction simulator, whatever the compression speed on the latter. The mean yield pressure values obtained using the two presses are different. Finally, the Stylcam 100R seems to be a good tool for characterising tabletting properties of powders, except for the Heckel's model probably due to an unadapted equation of deformation and a lack of accuracy of the displacement transducers. Future improvements should allow correcting these two points. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2874,2885, 2010 [source]

Monetite (CaHPO4) Synthesis in Ethanol at Room Temperature

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009
A. Cuneyt Tas
A straightforward process was developed to synthesize monetite (CaHPO4, dicalcium phosphate anhydrous) powders at room temperature (21°±1°C) in ethanol solutions. The process reported here constitutes an alternative to well-publicized monetite synthesis procedures based on the dehydration of brushite (CaHPO4·2H2O, dicalcium phosphate dihydrate) powders either in acidic, hot (70°,95°C) aqueous solutions or in drying ovens (200°,225°C). Submicrometer monetite powders were synthesized in ethanol (ethyl alcohol) solutions containing small aliquots of concentrated H3PO4 (orthophosphoric acid, 85%). Precipitated CaCO3 (calcium carbonate, calcite form) powders with submicrometer particles were simply stirred in the above solutions in glass bottles for 3 h. The starting Ca/P molar ratio in the synthesis bottles was 0.50. Monetite powders obtained with a stacked-nanosheets particle texture did not contain any unreacted CaCO3. Monetite powders were also found to have the ability to completely transform into apatitic (apatite-like) calcium phosphate powders when soaked in calcium-containing saline solutions (i.e., 142 mM Na+, 5 mM K+, and 50 mM Ca2+ in water) for 6 days at 37°C. [source]

Improvement of Mechanical Properties of Self Setting Calcium Phosphate Bone Cements Mixed With Different Metal Oxides

MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 12 2003
U. Gbureck
Calciumphosphat Zemente; Metalloxide; Mechanische Eigenschaften Abstract Calcium phosphate cements (CPC), based on multicomponent powder mixtures of calcium orthophosphates with medium particle sizes in the region of 1 - 20 ,m, set isothermally in an aqueous environment to form hydroxyapatite (HA). HA cement reactants include tetracalcium phosphate (TTCP), tricalcium phosphate (TCP), dicalcium phosphate anhydrate (DCPA), dicalcium phosphate dihydrate (DCPD), monocalcium phosphate (MCPA) or octacalcium phosphate (OCP). The aim of this study was to improve the mechanical performance of TTCP / DCPA cement by adding several metal oxides to tetracalcium phosphate during the fabrication process. Cements based on tetracalcium phosphate mixed with silica or titanium oxide showed significant increases in compressive strength, approximately 80 - 100 MPa, whilst no change in the mechanical behavior of CPC was observed if zirconia was added. X-ray diffraction measurement confirmed the setting reaction of doped cements was similar to that of pure CPC. Low crystalline HA was found to be the main constituant of set cement; additional phases, such as calcium titanate or calcium zirconate, were not involved in the reaction. A mechanical reinforcement effect was thought to result from changes in the thermodynamic or kinetic solubilities of doped tetracalcium phosphates, this would lead to slower HA crystal formation and a more cross-linked cement structure. Verbesserung der mechanischen Eigenschaften von Calciumphosphat-Zementen durch Modifikation mit verschiedenen Metalloxiden Calciumphosphat-Zemente, CPC, bestehen aus Pulvermischungen verschiedener Calcium orthophophate, beispielsweise Tetracalciumphosphat (TTCP), Tricalciumphosphat (TCP), Dicalciumphosphatanhydrid (DCPA), Dicalciumphosphatdihydrat (DCPD), Monocalcium phosphatanhydrid (MCPA) oder Octacalciumphosphat (OCP) mit durchschnittlichen Partikelgrößen im Bereich von 1 , 20 ,m. Die Zemente binden in wässriger Umgebung isotherm zu Hydroxylapatit ab. Das Ziel dieser Arbeit war die Verbesserung materialspezifischer Eigenschaften , wie die mechanische Festigkeit - eines TTCP / DCPA-Zementes durch die Verwendung von Metalloxiden im Syntheseprozess von Tetracalciumphosphat. Zemente, die aus mit Silicium- oder Titandioxid versetzten Tetracalciumphosphaten hergestellt wurden, zeigten eine deutliche Steigerung der Druckfestigkeit auf Werte von 80 , 100 MPa, während im Falle von Zirkoniumdioxid keine Änderung der mechanischen Stabilität erreicht werden konnte. Röntgendiffraktometrische Untersuchungen ergaben, dass die Abbindereaktion dieser Zemente ähnlich der eines reinen TTCP / DCPA-Zements verläuft. Jeweiliges Hauptprodukt war niedrigkristalliner Hydroxylapatit, die im Herstellungsprozess von Tetracalciumphosphat entstandenen Nebenprodukte Calciumtitanat bzw. ,zirkonat waren nicht an der Abbindereaktion beteiligt. Ein Grund für die Steigerung der mechanischen Stabilität ist offensichtlich die Veränderung der kinetischen und thermodynamischen Löslichkeit der synthetisierten Tetracalciumphosphate, die zu einer langsameren Abbindereaktion und somit einer besseren Vernetzung in der Hydroxylapatitstruktur führt. [source]