Preparation ion exchange

Compared with conventional type, the tentacle type exhibits a marked increase in selectivity. The results observed for preparative ion exchangers of tentacle type prompted the author to test this structural arrangement of the binding groups also for analytical materials based on porous silica. Figure 12 reveals that the tentacle-specific selectivity is fully preserved when the matrix is changed. 

The free oil can be determined by an ion exchange HPLC technique. A solution of the sample in ethyl alcohol is analysed by high-performance ion exchange chromatography using a specially prepared ion exchange resin stationary phase, ethanol mobile phase, and differential refractive index detection. 

Materials similar to Nation containing immobilized —COO- or —NR3+ groups on a perfluorinated skeleton were also synthesized. These are available in the form of solid membranes or solutions in organic solvents the former can readily be used as solid electrolytes in the so called solid polymer electrolyte (SPE) cells, the latter are suitable for preparing ion-exchange polymeric films on electrodes simply by evaporating the polymer solution in a suitable solvent. 

Some zeolites have the ability to exchange sodium for calcium and thereby function as water softeners by removing Ca2+. After the zeolite has become saturated with Ca2+, it can be renewed by washing it in a concentrated NaCl solution to restore the Na+ ions. Zeolites are also used to prepare ion exchange resins, as molecular sieves and as catalysts. 

Size separation columns need to be long and thin to provide a sufficiently long separating path. Preparative ion exchange and affinity columns should be short and broad to provide a large separating surface. 

Kravtchenko, T. P., Voragen, A. G. J., and Pilnik, W. (1992). Studies on the intermolecular distribution of industrial pectins by means of preparative ion-exchange chromatography. Carbohydr. Polym. 19 115-124. 

As another example, let s consider the chemical reactions that are used to prepare ion exchange resins. These resins are composed of small polymer beads that can be used to exchange one ion for another in aqueous solutions. The polymer that is used in these applications is a cross-linked polystyrene. To make this material, styrene containing a small amount of divinylbenzene is polymerized. Each vinyl group of divinylbenzene can become part of a separate polymer chain, so these groups act as cross-links between chains. The resulting polymer is used in the form of small beads that are completely insoluble in typical solvents. 

As noted in Section VIII, preparative ion-exchange and hydrophobic interaction chromatographic procedures have come to occupy, from practical considerations, central positions in the fractionation of protein mixtures, typically enabling purification factors in the range of 10- to 100-fold.6,364,366... 

Gallant, S., Vunnum, S., and Cramer, S. M. (1996). Optimization of preparative ion-exchange chromatography of proteins-linear gradient separations. /. Chromatogr. 725, 295-314. 

The hydroboration of ( )-baikiain (4,5-dehydro-( )-pipecolinic acid) via its JV-benzyloxycarbonyl methyl ester derivative (134) led, after oxidation and removal of the protecting groups, to 72% trans-5-hydroxy-( + )-pipecolinic acid (136) and 28% (raw.s-4-hydroxy-( + )-pipecolinic acid (135), separable by preparative ion-exchange column chromatography.118... 

Gerberding, S.J. Byers, C.H. Preparative ion-exchange chromatography of proteins from dairy whey. J. Chroma-togr., A 1998, 808 (1-2), 141-151. 

Central nervous system depressants Hypnotics and sedatives Barbiturates in pharmaceutical preparations Ion-exchange Zipax SAX Alkaline (0.01M sodium borate/ 0.03M sodium nitrate) or acid (0.01M acid) mobile phases... 

Sympathomimetics Imidazoline derivatives and their degradation products in the intact form of these drugs or in their pharmaceutical preparations. Ion-exchange Zipax SCX and SAX Aqueous mobile phase buffered at pH 11.4-12.4... 

Many attempts to prepare ion exchange membranes having permselectivity for specific ions and to find electrodialysis methods to achieve such a purpose have been made. In this chapter, studies on the modification of ion exchange membranes and electrodialysis methods to permeate specific ions through the membrane, mainly in electrodialysis, are explained. 

Several peptides with specific properties may be prepared from milk proteins, either in vivo or in vitro some may have commercial potential and can be produced on a relatively large scale by preparative ion-exchange chromatography. 

Homogeneous ion-exchange membranes can also be prepared by the introduction of anionic or cationic moieties into a performed film. Starting with a film makes the membrane preparation rather easy. A typical example for this mode of preparing ion-exchange membranes is the sulfochlorination and amination of polyethylene sheets according to the following reaction scheme [24] ... 

For preparative ion-exchange separations of nucleotides a volatile eluent is desirable and the use of ammonium carbonate and ammonium acetate have been described (Linz, 1983). 

Sulfonation reactions of polystyrene and its copolymers with divinyl benzene are carried out commercially to prepare ion exchange resins. Partial sulfonations of polystyrenes are achieved in the presence of ethers. When more than 50% of the aromatic rings are sulfonated, the polymers become water soluble. At lesser amounts of sulfonation (25-50%), the polymers are solvent soluble. ... 

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