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.
Figure 4 compares the three model predictions for the fractional precipitation of asphaltenes from n-pentane.
In this study, the best fits of average molar mass fractional precipitation were obtained with a "monomer" molar mass of 750 g/mol and with a decreasing probability of self-association for larger aggregates.
Effect of resins on asphaltene self-association and solubility
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.
Aventis obtains United States patent

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