Fractional Precipitation

fractional precipitation

[¦frak·shən·əl prə‚sip·ə′tā·shən]
(analytical chemistry)
Method for separating elements or compounds with similar solubilities by a series of analytical precipitations, each one improving the purity of the desired element.

Fractional Precipitation

 

a method of separating a mixture of substances by means of their gradual precipitation from a solution. The possibility of quantitative separation of a mixture depends on the ratio of the original concentrations of compounds being precipitated and on the values of their solubility product. Coprecipitation of a more soluble compound with a less soluble one is possible in the process of fractional precipitation. The methods of fractional precipitation, which are generally used for separation of mixtures of substances that are close in terms of chemical properties and solubility, are extremely labor-intensive.

REFERENCE

Kolthoff, I. M., and E. B. Sandell. Kolichestvennyi analiz, 3rd ed. Moscow-Leningrad, 1948. (Translated from English.)
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As expected, the fractional precipitation decreases as the proportion of resins increases.
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Aventis Behring GmbH (Marburg, Germany) has patented a process for the preparation in pure form of the protease activating blood clotting factor VII and/or its proenzyme by the use of a chromatography separation processes and/or fractional precipitation. The process used may include adsorption on calcium phosphate/hydroxyapatite, a hydrophobic matrix, a chelate matrix, a matrix on which heparin or a substance related to heparin, such as heparin sulfate or dextran sulfate, is immobilized, or a matrix that is coated with an immobilized monoclonal or polyclonal antibody directed against the protein to be isolated, or F(ab) or F(ab).sub.2 fragments of antibodies directed against the protein to be isolated.
Aventis obtains United States patent

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