Precipitation inorganic component

One of the key steps in any isotope dilution analysis concerns the isolation and purification of the diluted activity, plus the measurement of its specific activity. Two techniques are usually preferred for the separation precipitation and solvent extraction. As a purification step, precipitation has the advantage that the precipitate can easily be weighed at the time of separation, thereby allowing a quick determination of the specific activity. The main problem with the use of precipitation techniques involves the occurrence of co-precipitation phenomena, in which unwanted materials are precipitated along with the desired substance, thus altering the sample specific activity. Precipitation techniques are used for the isolation of inorganic components. 

The diblock copolymer micelles can be used to prepare inorganic nanoparticles ranging from 1 to 10 nm in diameter [12,30]. In the so-called microreactor approach, the core block, which is shielded by the shell interacts preferentially with the inorganic molecules in solution causing their precipitation inside the micelles. If the inorganic component was a metal salt, the latter could be reduced to a free metal state by either chemical or temperature treatment. The size of thus obtained metal cluster was controlled by the micelle size depending on the... 

Ferritin consists of a shell of protein subunits surrounding a core of ferric hydroxyphosphate. For some time the inorganic component of ferritin was thought to be attached to the surface of the protein (65). However, the demonstration that ferritin and apoferritin have the same electrophoretic mobilities and are precipitated equally well with horse ferritin antibody (66) together with electron microscopic evidence (67) clearly showed that the iron is concentrated in the middle of the apoferritin protein shell. The iron micelle has a diameter of 70—75 A whilst the protein shell has a diameter of the order of 120 A (67—70, 62). Somewhat lower values are found in dried preparations (71, 72). The micelle contains ferric iron, predominantly as (FeO.OH) but also with some 1—1.5% phosphate (4,50) and it seems that the iron phosphorus ratio is constant for ferritins of different iron content (52). The composition (FeO.OH) g. (FeO.OPOgHg) has been suggested (73, 74). The percentage of iron in the micelle on this basis is 57%. 

Proteins such as rhBMP can be incorporated into calcium phosphate layers when biomimetically co-precipitated with the inorganic components (Liu et al., 2004). For example, rhBMP-2 (0.1-10pgml-1) retains its osseoinductive potential when incorporated into the crystal lattice of hydroxyapatite in a dose-dependent manner as ascertained by protein blot staining and enzyme-linked immunosorbent assay (ELISA). The positive osseogenicity of rhBMP-2 was assessed quantitatively by monitoring ALP activity (see Section 7.10.3.1) on rat BMSCs grown directly on the calcium phosphate coatings. 

The down-hole oil and gas environment is especially challenging. Conditions vary from well to well but usually involve a corrosive, high temperature environment with a multitude of organic and possibly inorganic components in the fluid being removed from the well. During operation of the well, various substances may precipitate on... 

In a parallel study, a biocompatible composite made of sulphonated PSU and HAp was prepared and characterized. The incorporation of HAp was achieved by spontaneous precipitation of HAp at controlled conditions of pH and temperature. The time of the precipitation process was used to regulate the content of inorganic component in the composite. The composite material prepared in this experiment contained 9 wt% of HAp and 91 wt% of polymer. Analysis of the kinetic results of the crystallization process showed that the growth of HAp on the film-shaped composite material followed a polynuclear (nuclei above nuclei) crystal growth mechanism [103],... 

In view of the selective character of many colorimetric reactions, it is important to control the operational procedure so that the colour is specific for the component being determined. This may be achieved by isolating the substance by the ordinary methods of inorganic analysis double precipitation is frequently necessary to avoid errors due to occlusion and co-precipitation. Such methods of chemical separation may be tedious and lengthy and if minute quantities are under consideration, appreciable loss may occur owing to solubility, supersaturation, and peptisation effects. Use may be made of any of the following processes in order to render colour reactions specific and/or to separate the individual substances. 

The inorganic elements in aqueous solution reactions, both acid-base complex formation, precipitation and oxidation/reduction, frequently come rapidly to equilibrium when no more reactions are possible. The implication is that in the environment and in organisms many of their properties cannot change unless circumstances change, for example the introduction of new components. 

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