Calcium-phosphorus ratio solution

Depending on the calcium/ phosphorus (Ca/P) molar ratio and solubility of the compound, it is possible to obtain numerous calcium phosphates of different composition. Molar Ca/P ratio and solubility are connected with the pH of the solution. Majority of materials of this class are resorbable and dissolve when inserted in a physical environment. Calcimn phosphates that are most frequently used in the biomaterial field are demonstrated in Table 1 (Dorozhkin, 2009c El Kady, 2009 Shi, 2006). 

Figure 9 shows several TPD spectra of mass 31 (P) at different exposure times to calcium phosphate solution (55). Phosphorus desorption from alumina riiows broad features from 450-700 K, the residual salt peak at 980 K, and a high tenq>erature feature, vAach occurs between 1400 and 1560 K. Variation in the tenq>erature associated with the high tenq)erature desorption feature may be a result of variations in heating rate or thermocouple placement. Unlike the titania spectra, the large feature at 1200 K is absent. In addition, at least one new feature can be observed at approximately 450-700 K Figure 9b shows the corre onding calcium and potassium desorption features. The ratio of calcium and potassium ions to pho horus is conq)arable, but for longer exposures, this ratio decreases dramatically. For a 30 hr. e q>osure, the calcium and potassium to phosphorus ratios drop to less than 1% of the solution concentration. Integration of several phosphorus desorption ectra provide the data for an adsorption isotherm shown in Figure 8. Onset of rapid uptake of pho hate is observed between 20-25 hr.

Standard solution (containing tin or titanium for barium and calcium, zirconium for phosphorus, and nickel for zinc) is poured into an X-ray cell. Total net counts (peak intensity— background) for each element and its respective internal standard are collected at their appropriate wavelengths. The ratios between elemental and internal standard counts are calculated and converted into barium, calcium, phosphorus, or zinc concentrations, or a combination thereof, from calibration curves. 

When the solution contained calcium and phosphorus the Ca/HEDP molar ratio measured on the sample surface was between 0.4 and 0.8. In the case of a Ca/HEDP = 3 molar ratio in the solution (Fig. 9-44), an increased amount of adsorbed HEDP was observed. 

In the UK, it is recommended that infants who are not breast fed are fed modified milks until at least 6 months of age. These contain less solute, protein, sodium, calcium and phosphorus than cows milk. The Codex Alimentarius lays down international standards for infant feeds Some modified milks are based on demineralised whey and milk to reduce the protein content and change the whey casein ratio examples are given in Table 1. This provides an amino acid composition more closely resembling that of human milk but does not overcome the problem that beta-lactoglobulin and other cows milk proteins are introduced and the anti-infective factors provided by human milk are absent. 

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