Chromatography precipitation

Degenhardt, U.H. et ah. Centrifugal precipitation chromatography a novel chromatographic system for fractionation of polymeric pigments from black tea and red wine, J. Agric. Food Chem., 49, 1730, 2001. 

Fractionation by means of precipitation chromatography was suggested by Baker and Williams95. The method has been reviewed recently96,97. Numerous applications to copolymer investigation have been reported 98 -107). 

After a product is recovered or isolated, it may need to be purified further. The purification can be accomplished by numerous methods such as precipitation, chromatography, electrophoresis, and ultrafiltration. 

Another powerful method combines gel permeation chromatography with gradient elution-precipitation chromatography [20,21]. Simultaneously determining the breadths of both the molecular weight and compositional distributions can provide insights into structure-property relationships and the control of the polymerization process. 

Mori S (1996) Characterization of styrene-acrylonitrile copolymers by size exclusion chromatography/stepwise gradient elution-liquid precipitation chromatography. Int J Polym Anal Charact 2 185-92. 

Liquid-liquid extraction, precipitation, chromatography, activated carbon... 

Reduction in viral infectivity occurs by inactivation of virus or by removal of virus particles. During removal steps, virus is not inactivated but is separated from the protein of interest using methods such as precipitation, chromatography, or filtration. For example, during an ethanol precipitation step, ethanol is added to a suspension to precipitate unwanted contaminating proteins and viruses. The ethanol-containing suspension is then centrifuged so that the contaminants in the precipitated paste fraction can be separated from the product in the effluent fraction. 

Paderina, F. P., Ol shanova, K. M., Morozova, M. N. Concentration of chromium and lead from highly dilute solutions by precipitation-chromatography. Nor. Metody Khim. Anal. Mater. No. 2, 63 (1971) C. A. 77,13 634z (1972)... 

Aleskovskaya, V. N., Aleskovskii, V. B. Determination of microamounts of certain cations by peak precipitation-chromatography on paper impregnated with slightly soluble diethyl-dithiocarbamates. 2h. AnaL Khim. 25, 243 (1970) Ref. C. A. 75, 10 423m (1970)... 

Kokk, K. Y., Aleskovskii, V. B. Determination of copper in micro amounts of cadmium selenide by paper precipitation-chromatography. Izo. Vysshikh. Uchebn. Zavedenii, Khim. i Khim. TeknoL 7, 564 (1964) C. A. 62, 3 392f (1965)... 

Figure 2 illustrates serum protein separation by centrifugal precipitation chromatography the chromatographic tracing of the elution curve in Fig. 2a and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of separated fractions in Fig. 2b. In this example, lOOmL of normal human serum (pooled) was diluted to 1 mL and introduced into the separation channel. The experiment was initiated by filling both upper and lower channel with 75% AS solution followed by sample...

Fig. 2 Separation of human serum proteins by centrifugal precipitation chromatography (a) Elution curve (b) SDS-PAGE analysis of separated fractions.

Y. Ito, Centrifugal precipitation chromatography applied to fractionation of proteins with ammonium sulfate, J. Liquid Chromatogr. Related Technol. 22(18) 2825 (1999). 

Y. Ito, Centrifugal precipitation chromatography Principle, apparatus, and optimization of key parameters for protein fractionation by ammonium sulfate precipitation, Anal. Biochem. 277 143 (2000). 

Several useful CCC systems have been developed from these centrifuge schemes. The nonplanetary scheme has been used for toroidal coil CCC [3,4], centrifugal precipitation chromatography [5], and on-line apheresis in the blood bank [6,7]. The nonsynchronous scheme has been applied to partition of cells with polymer phase systems and also to cell elutriation with physiological solutions [8,9]. The type J synchronous scheme is further developed into a highly efficient CCC system called high-speed CCC (HSCCC) [10]. 

Spain, J. D. Precipitation Chromatography. Diffusion and Precipitation of Metal Sulfides on Agar Gel Columns. Analytic. Chem. 32, 1622 (1960). 

Elements of Group VI suitable eluents and the migration behaviour of selenate and selenite ions was brought out, and a method for the clear separation of the ions by the technique of precipitation chromatography described. 

Separation of free immunoreactant from reactants immobilized on plastic is achieved simply by decanting, aspirating or retrieving the solution, in contrast to the often cumbersome techniques used in other systems (precipitation, chromatography, centrifugation, nonspecific adsorption on charcoal, talc or dextran). This simplicity has a direct, positive effect on the reproducibility and sensitivity of the assay. 

The target material for irradiation must be pure and preferably monoiso-topic or at least enriched isotopically to avoid the production of extraneous radionuclides. Radionuclides are separated from the target material by appropriate chemical methods such as solvent extraction, precipitation, chromatography, ion exchange, and distillation. Cyclotron-produced radionuclides are typically neutron deficient and, therefore, decay by / + emission or electron capture. Also, the radionuclides, which are different from the target nuclides, do not contain any stable (or cold ) atoms and are called carrier-free. Another term for these preparations is no-carrier-added (NCA), because no cold atoms have been intentionally added to the preparations. 

Crystallisation, precipitation, chromatography, and electrophoresis belong to this category of separatory methods. 

Since these examples are for research-laboratory work, economic concerns such as solvent recovery, reuse, or cost are not considered. Solvents such as acetonitrile or tetrahydrofuran have some immiscibility properties that are quite useful in laboratory work. However, economic costs would likely prevent their use in a commercial process. The goal in each example is to end up with a solvent extract that can easily be vacuum-concentrated and used in final purification steps (i.e., crystallization, precipitation, chromatography). 

Interesting results can also be obtained by the combination of steric exclusion with other physicochemical processes like selective complexation [31], selective precipitation [29], electrophoresis [32] or immunophoresis, as the selective complex-ing agent can serve the individually added substance and also the eluent itself [33]. The combination of gel chromatography with precipitation chromatography is called zone precipitation [29]. 

Precipitation chromatography, as proposed by Baker and Williams and improved in our laboratory, has a systematic error caused by the nonuniformity of the fractions. This error can be eliminated if the fraction nonuniformity is determined by a special kind of mixing experiment. Another interfering effect which is produced in anionic polymerizates by traces of impurities can be eliminated by testing the BW fractions by GPC. Exactly determined molecular weight distribution functions of samples which are synthesized under well defined kinetic conditions provide much information about elementary reactions of the polymerization process. This is demonstrated by some examples of the anionic polymerization of styrene and methyl methacrylate. 

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