Calcium strontium phosphate

Leroux L, Lacout JL (2001a) Synthesis of calcium-strontium phosphate fluor-hydroxylapatites by neutralisation. Phosph Sulf Sil Rel Elements 173 27-38 Leroux L, Lacout JL (2001b) Preparation of calcium strontium hydroxylapatites by a new route involving calcium phosphate cements. J Mater Res 16 171-178... 

Admixture incompatibilities - Magnesium sulfate in solution may result in a precipitate formation when mixed with solutions containing Alcohol (in high concentrations) alkali carbonates and bicarbonates alkali hydroxides arsenates barium calcium clindamycin phosphate heavy metals hydrocortisone sodium succinate phosphates polymyxin B sulfate procaine hydrochloride salicylates strontium tartrates. 

Among condensed phosphate systems with polyvalent cations, the very complicated calcium salts have been much studied and a great number of compounds have been detected, often with several modifications (5, 27, 28, 34, 54, 79, 186, 137, 191, 198, 204, 211, 276, 805, 830). In this system special interest attaches to the occurrence of crystalline cross-linked phosphates (see Section V) and of calcium pentaphosphate, CayiPsOis (see Section IV,D,/). The end-product obtained by heating Ca(H2P04)2 in the free atmosphere is the high-molecular calcium polyphosphate, which crystallizes in several forms. The condensed strontium phosphates (246, 805) are similarly complicated and cannot readily be made the subject of a brief review. 

Calcium Multiple physiologic actions through regulation of multiple enzymatic pathways Strontium suppresses bone resorption and increases bone formation, calcium and phosphate required for bone mineralization Osteoporosis, osteomalacia, deficiencies in calcium or phosphate Ectopic calcification... 

This is by far the most frequently encountered interference in AAS. Basically, a chemical interference can be defined as anything that prevents or suppresses the formation of ground state atoms in the flame. A common example is the interference produced by aluminium, silicon and phosphorus in the determination of magnesium, calcium, strontium, barium and many other metals. This is due to the formation of aluminates, silicates and phosphates which, in many instances, are refractory in the analytical flame being used. 

The tri-calcium, barium, and strontium phosphates are members of an isostructural series M3(P04)2, where M = Ca, Ba, Sr, etc. The minerals formed by Ca are very important in bioceramics, and because Ba and Sr are fission products (i.e., formed as by-products in nuclear reactions), apatite minerals play a major role in their stabilization for disposal (see Chapter 17). Within these common structures, however, calcium phosphate goes through several phase changes at different temperatures. These phases are labeled as (3, a, a, etc. The reader is referred to Refs. [1,2] for details. 

Plasma Concentrations of Calcium and Phosphate Although the mean response to changes in plasma cedcium is a chemge in the secretion of peuathyroid hormone, the activity of calcidiol 1-hydroxyleise in kidney slices is decreased directly by high concentrations of cedcium in the incubation medium. Cedcium heis no direct effect on the activity of calcidiol 24-hydroxylase under these conditions. Strontium and cadmium edso inhibit ctdcidiol 1-hydroxylase. 

Sol-gel methods are used to prepare a heterogeneous, nanometer composite of calcium zirconium phosphate and strontium zirconium phosphate, Cao.sSro.sZrsOn. In this composite, individual domains both expand and contract upon heating, leading to a material with virtually zero thermal expansion over the range 0-500 °C. 

Characteristic Unit Zinc aiuminum molybdenum phosphate Zinc calcium strontium aluminum phosphate silicate... 

Several papers deal with magnesium determination in blood and urine. Willis (WIO) analyzed serum in the air-acetylene flame and found no effect from the presence of sodium, potassium, calcium, or phosphate, but states that an enhancement was seen in serum diluted with water only, probably due to serum proteins. This interference was controlled by addition of strontium or EDTA. Sensitivities were the same in the eoal gas-air and air-acetylene flame, indicating complete atomization of magnesium. In urine (W13) no interference was encountered and determinations were performed on samples directly diluted with water. 

The strontium preconcentration by coprecipitation of calcium and strontium phosphates requires magnetic stirrers with heating plate and a centrifuge collecting the precipitate. A drying cabinet is used to gently dry the precipitate of calcium and strontium phosphates. 1220 Quantulus counter is routinely used for the determination of low-level radioactivities. 

The sample is mixed and heated to 80-90 °C on a magnetic stirrer. Then precipitation of calcium and strontium phosphates in alkaline medium (pH = 8 - 9) is performed by adding concentrated ammonium hydroxide. Precipitate is allowed to settle for at least 2 hours to one night. Then the supernatant is discarded. The precipitate is collected in a centrifuge tube and rinsed with alkalized water. Precipitate is dried in a warm atmosphere at 80°C. 

In the case of milk, direct application of the nitric acid separation to a solution of the ash usually gives low strontium yields. The calcium, strontium and barium are therefore concentrated by an initial phosphate precipitation. The mixed phosphates are then dissolved in an acid and the general procedure continued from that point. 

In the mouth, mineralization is controlled partly by proteins such as statherin from the salivary gland, which maintains a supersaturation of calcium and phosphate in the mouth. The basic mineral in tooth enamel is hydroxyapatite, in which it is possible to substitute Sr(II) for Ca(II), and F for OH isomorphously, hence the use of strontium and fluoride salts in toothpastes, said to confer extra strength to the enamel and antibacterial properties. 

By use of releasing agents Considering the reaction M-X-i-R = R- Xh-M, it becomes evident that an excess of the releasing agent (R) will lead to an enhanced concentration of the required gaseous metal atoms (M) which will be of special significance if the product R-X is a stable compormd. Hence in the determination of calcium in presence of phosphate the addition of excess of strontium chloride to the test solution will lead to the formation of strontium phosphate and the calcium can then be determined in an acetylene-air flame without any interference due to phosphate. Also addition of EDTA to a calcium solution before analysis may increase the sensitivity of the subsequent flame spectrophotometric determination which may be due to the formation of an EDTA complex of calcium which is readily dissociated in the flame. 

Inorganic anodic and mixed Cl present water-soluble salts of ammonium, alkali (sodium, potassium), alkaline-earth (calcium, strontium, magnesium, barium) and other (zinc, lead) metals containing active anions in their molecules (nitrates, nitrites, chromates, carbonates, phosphates, molybdates, silicates). ... 

No. 7 Zinc Phosphate. See Zinc phosphate No. 8 White] No. 9 NCS] No. 9 White] No. 10 White. See Calcium monocarbonate No. 11 Strontium Phosphate. See Strontium phosphate... 

Synonyms Phosphoric acid, strontium salt Strontium orthophosphate Empirical H3O4P xSr Properties M.w. 711.34 Toxicology TDLo (oral, rat, 6 wks continuous) 50,400 mg(Sr)/kg may cause wt. loss, changes in calcium/phosphorus Uses Corrosion-inhibiting pigment Trade Name Synonyms No. 11 Strontium Phosphate [Nichem]... 

Inorganic inhibitors incorporated into coatings include borate, chromate, molybdate, phosphate, phosphite, or silicate, typically as anticorrosive pigments (salts) of the metals aluminum, barium, calcium, strontium, or zinc. It should be noted that many of the inorganic inhibitors are anions and are, therefore, candidates for incorporation as dopant anions into CP coatings for controlled release. 

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