scholarly journals Considerations and Influencing Parameters in EDS Microanalysis of Biogenic Hydroxyapatite

2020 ◽  
Vol 11 (4) ◽  
pp. 82
Author(s):  
Florin Miculescu ◽  
Cristina Luță ◽  
Andreea Elena Constantinescu ◽  
Andreea Maidaniuc ◽  
Aura-Cătălina Mocanu ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Mechanical Vibration ◽  
Powder Particle Size ◽  
Heat Treated ◽  
Primary Identification ◽  
Acceleration Voltage ◽  
Eds Microanalysis

Calcium phosphates (CPs) used as biomaterials have been intensively studied in recent years. In most studies, the determination of the chemical composition is mandatory. Due to the versatility and possibilities of performing qualitative and quantitative compositional analyses, energy dispersive spectrometry (EDS) is a widely used technique in this regard. The range of calcium phosphates is very diverse, the first method of approximating the type of compound being EDS microanalysis, by assessing the atomic Ca/P ratio. The value of this ratio can be influenced by several factors correlated with instrumental parameters and analysed samples. This article highlights the influence of the electron beam acceleration voltage (1 kV–30 kV) and of the particle size of calcium phosphate powders on the EDS analysis results. The characterised powders were obtained from bovine bones heat-treated at 1200 °C for 2 h, which have been ground and granulometrically sorted by mechanical vibration. The granulometric sorting generated three types of samples, with particle sizes < 20 μm, < 40 μm and < 100 μm, respectively. These were morphologically and dimensionally analysed by scanning electron microscopy (SEM) and compositionally by EDS, after the spectrometer was calibrated with a standard reference material (SRM) from NIST (National Institute of Standards and Technology). The results showed that the adjusting of acceleration voltage and of the powder particle size significantly influences the spectrum profile and the results of EDS analyses, which can lead to an erroneous primary identification of the analysed calcium phosphate type.

scholarly journals Ultrasonic application and spray drying during amorphous calcium phosphate synthesis

2019 ◽  
Vol 8 (4) ◽  
pp. 711-714
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Calcium Phosphate ◽  
Spray Drying ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Calcium Content ◽  
Synthesis Process ◽  
Particle Sizes ◽  
Ultrasound Application

Hydroxyapatite, amorphous calcium phosphates, calcium triphosphate and calcium octaphosphate are the main components present in bones and teeth. Calcium phosphates are easily synthesized, playing an important role in regenerative medicine, being able to be used as bone implants. There are different ways of synthesizing phosphates, the most commonly used being wet chemical method. The objective of this work was to study the influence of the use of ultrasound and spray drying on the synthesis of amorphous calcium phosphate. Two synthetic variants were studied. One without ultrasound application and the other with ultrasound application. The samples obtained were characterized by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy. The particle size by electron microscopy and the calcium content by atomic absorption was determined. The results showed that when spray drying is applied, particle sizes of less than 261 nm are obtained in the samples synthesized without ultrasound application, being less than 59 nm in the samples synthesized with ultrasound application. The statistical analysis by ANOVA showed significant differences between the particle sizes of the samples synthesized without ultrasound application and the samples synthesized by applying ultrasound. In both cases the particles were spherical. The results obtained show that the application of ultrasound during the synthesis process decreases the particle size, increasing the surface area, which favors the spray drying process.

Determination of Phosphate Composition of Stock Food Calcium Phosphate

1963 ◽  
Vol 46 (2) ◽  
pp. 312-315
Author(s):  
D N Bernhart ◽  
W B Chess
Keyword(s):  
Thermal Stability ◽  
Calcium Phosphate ◽  
Water Solubility ◽  
Calcium Phosphates ◽  
Thermal Conversion ◽  
Food Grade ◽  
Stock Food ◽  
Commercial Stock ◽  
Thermal Stability Of

Abstract A method has been developed to determine the phosphate composition of commercial stock food grade calcium phosphates with an over-all accuracy of ± 2% absolute. It is based on the EDTA solubility of all the o-phosphates, water-solubility of monocalcium phosphate, thermal conversion of dicalcium phosphate to pyrophosphate, and thermal stability of tricalcium phosphate. Results are given for both known and commercial samples.

Effect on Drying Conditions on Amorphous Calcium Phosphate

2014 ◽  
Vol 631 ◽  
pp. 99-103 ◽  
Author(s):  
Agnese Brangule ◽  
Kārlis Gross
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Intermediate Phase ◽  
Calcium Phosphates ◽  
Ftir Spectra ◽  
The Body ◽  
Drying Methods ◽  
Dry Conditions ◽  
Drying Conditions

Amorphous calcium phosphate (ACP) plays an important role in the body and can be used as an intermediate phase for forming calcium phosphates. All ACPs are thermodynamically unstable compounds, unless stored in dry conditions or at low temperature (-18oC), and spontaneously undergo transformation to crystalline calcium phosphates (CaP). This work will investigate the influence of drying on the stability of ACP. ACPs powders were prepared by wet synthesis; mixing solution made of Ca (NO3)2∙4H2O and 30% ammonia with (NH4)2HPO4 and (NH4)2CO3 solution at room temperature. The suspension was stirred, filtered and washed several times with deionized water containing ammonia. ACP samples were dried at different conditions and with different drying agents (DA). XRD and FTIR spectra showed poorly crystallinity powders after drying. Some FTIR spectra indicated residual organic compounds from drying. The Rietveld’s method and Schrrer’s relationship estimated the particle size (0.5 – 20 nm) of ACP. Thermogravimetry (TG) revealed that the moisture (7% – 25%) is released upon drying, and the drying agents have no significant effect on. The drying methods are ordered to show which the most effective for removing moisture. By changing the drying conditions, it is a possible to obtain poorly crystalline ACPs with different particle size and moisture content.

scholarly journals Phosphorus retention by granulated apatite: assessing maximum retention capacity, kinetics and retention processes

2021 ◽  
Vol 83 (4) ◽  
pp. 792-802
Author(s):  
Laura Delgado-González ◽  
Bruno Lartiges ◽  
Mathieu Gautier ◽  
Stéphane Troesch ◽  
Pascal Molle
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Calcium Phosphates ◽  
Rate Coefficients ◽  
Phosphorus Retention ◽  
Retention Capacity ◽  
Phosphate Retention ◽  
Granule Surface

Abstract Natural apatites have previously shown a great capacity for phosphate retention from wastewater. However, its fine particle size distribution may lead to a premature clogging of the filter. Accordingly, a granulated apatite product was developed and manufactured in order to control the particle size distribution of the media. Experiments were conducted on laboratory columns to assess their phosphorus retention capacity, to identify the processes involved in phosphorus retention and to evaluate their kinetic rates. The results showed phosphorus retention capacities of 10.5 and 12.4 g PO4-P·kg−1 and kinetic rate coefficients in the range of 0.63 and 0.23 h−1 involving lower values than those found for natural apatites in previous studies. Scanning Electron Microscopy images showed that apatite particles in the granules were embedded in the binder and were not readily accessible to act as seeds for calcium phosphate precipitation. The retention processes differ depending on the supersaturation of the solution with respect to calcium phosphate phases: at low calcium concentrations (69.8 ± 3.9 mg·L−1), hydroxyapatite precipitates fill up the porosity of the binder up to a depth of 100–300 μm from the granule surface; at higher calcium concentrations (112.7 ± 7.4 mg·L−1) precipitation occurs at the granule surface, forming successive layers of hydroxyapatite and carbonated calcium phosphates.

scholarly journals Determination of the Ca/P ratio in calcium phosphates during the precipitation of hydroxyapatite using X-ray diffractometry

2013 ◽  
Vol 7 (2) ◽  
pp. 93-95 ◽  
Author(s):  
Zoltan Zyman ◽  
Dmytro Rokhmistrov ◽  
Kateryna Loza
Keyword(s):  
Phase Composition ◽  
Calcium Phosphate ◽  
Initial Data ◽  
Calcium Phosphates ◽  
Diffraction Method ◽  
Synthesis Time ◽  
X Ray ◽  
Simple Processing ◽  
Wet Synthesis

The applicability of the X-ray powder diffraction method to the determination of phase composition and Ca/P ratio in precipitates during the nitrous wet synthesis of hydroxyapatite (HA) has been shown. The plotted dependences of the phase composition and the Ca/P ratio on the synthesis time can be used as initial data for the development of new and simple processing routes of calcium phosphate ceramics based on HA of any desired composition.

Resorbable Biomaterials Based on Calcium Phosphates: Determination of In Vitro Solubility Applying the ISO 10993-14 (First Experiences)

2005 ◽  
Vol 284-286 ◽  
pp. 485-488 ◽  
Author(s):  
Ute Ploska ◽  
Renate Gildenhaar ◽  
Georg Berger
Keyword(s):  
Calcium Phosphate ◽  
Quantitative Determination ◽  
Degradation Products ◽  
Calcium Phosphates ◽  
Iso Standard ◽  
Medical Products ◽  
Precipitation Reactions ◽  
Working Procedure

To guarantee of the security of ceramic medical products the identification and quantification of the current degradation products is required by the ISO 10993-14 standard. Two methods - the gravimetrical registration of the mass loss and the quantitative determination of the leached ions by spectrometric methods - are planned. When checking the application of the ISO standard to calcium phosphate ceramics that can be used as implant materials a considerable difference in the results obtained with both methods was observed. It seems to be that precipitation reactions are responsible for that situation. To clear up the influence of precipitation reactions on the results the working procedure of the ISO standard was slightly modified. A first interpretation of the results is tried.

Effect of Sintering Temperature on Zinc Substituted Calcium Phosphate Ceramics

2017 ◽  
Vol 890 ◽  
pp. 209-212
Author(s):  
C.M. Mardziah ◽  
Mohamad Firdaus Abdul Wahid ◽  
Koay Mei Hyie ◽  
Nik Rozlin Nik Masdek ◽  
Z. Salleh
Keyword(s):  
Particle Size ◽  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Sintering Temperature ◽  
Calcium Phosphates ◽  
Precipitation Method ◽  
Zinc Ions ◽  
Major Phase ◽  
Calcium Phosphate Ceramics ◽  
Hydroxyapatite Phase

Calcium phosphate ceramics were substituted with several concentrations of zinc ions (0, 5, 10 and 15 mol%) using precipitation method. The effect of sintering temperature at 900 and 1000°C on zinc substituted calcium phosphate ceramics were observed. By increasing the sintering temperature, XRD peaks for zinc substituted calcium phosphate ceramics changed significantly. At sintering temperature of 900°C, hydroxyapatite phase was the major phase in the calcium phosphates containing 0 and 5 mol% zinc. However, at the sintering temperature of 1000°C, hydroxyapatite phase was partly transformed to another phase which was tricalcium phosphate. FESEM observations at sintering temperature of 1000°C exhibit that the particle size of the samples increased with addition of more zinc ions.

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