Cellulosic ion exchange resins

Sensors based on the above reaction scheme have been developed for Al3+, Zn2+, Cu2+, Ca2+, Pb2+, Hg2"1", K+, Li+, etc. A polycation, protamine sensor has also been developed using 2/7/-dichlorofluorescein octadecyl ester (DCFOE) doped in polymer membranes. However, most of these sensors are pH dependent due to the pH dependence of the cation complexation reactions. The cation ion indicators can be immobilized on any solid support, such as silica, cellulose, ion-exchange resin, porous glass, sol-gel, or entrapped in polymer membranes. 

Since the reaction has been reviewed recently (12) only a few additional facts will be mentioned. Many optically active cyanohydrins can be prepared (33) with e.e. s of 84 to 100% by the use of the flavopnotein D-oxynitrilase adsorbed on special (34) cellulose ion-exchange resins. Although the enzyme is stable, permitting the use of a continuously operating column, naturally only one enantiomer, usually the R isomer, is produced in excess. This (reversible) enzyme-catalyzed reaction is very rapid (34). Nonenzymic catalysts, such as the cinchona alkaloids, permit either enantiomer to be prepared in excess. 

Acculose. [Accurate Chem. Scientific] Cellulose ion exchange resins for research laboratory. 

Diethylaminoethyl cellulose ion exchange resin, weakly basic food purification... 

A more direct synthesis was then devised in which the required metal, as a suitable salt or complex in solution, is reacted with either an anionic or cationic cellulose ion exchange resin. The metal-cellulose material was then charred and activated as before to give a dispersion of metal particles in a porous carbon matrix. The method has the immediate advantage of extending the range of metals which can be incorporated to include those more electropositive than copper eg nickel. 

Thin-layer chromatography (TLC) Silica, cellulose, ion-exchange resin, controlled porosity solid Liquid Planar Adsorption (partition, ion-exchange, exclusion)... 

Although the interest in, and application of layer chromatography has historically resulted from the development of PC, it was soon replaced by thin-layer chromatography (TLC). In PC, only one stationary phase matrix is available (cellulose), at variance to TLC (silica, polyamide, ion-exchange resins, cellulose). Using a silica-gel plate, separation of a sample can be accomplished in approximately 1 h as compared with many hours on paper. The plate size is much smaller than the necessary paper size. Also, more samples can be spotted... 

Epoxy resin (Tufnol, Bakelite, Epophen) Styrene divinylbenzene ion exchange resins Reillex HPQ anion exchange resin Phenol/formaldehyde cation exchange resin Polyurethane Cellulose (as tissues)... 

Ion-exchange resins are cross-linked polymers which are typically polystyrene, cellulose or agarose based. Polystyrene is hydrophobic in nature and useful for inorganic ions and small molecules while cellulose and agarose are hydrophilic and more useful for the larger, biologically important molecules, e.g. proteins and nucleic acids, which either would be adversely affected by a hydrophobic environment or could not gain access to the small pore structure. 

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