Weak anion-exchanger

Highly active catalysts have been produced by adsorption of lipases onto macroporous acrylate beads, polypropylene particles and phenol-formaldehyde weak anion exchange resins. Protein is bound, presumably essentially as a monolayer, within the pores of the particles. The large surface area of the particles (10m2 g 1) means that substantial amounts of protein can be adsorbed, and the pores are of sufficient size to allow easy access of reactants to this adsorbed protein. 

The column, designated as TSKgel DEAE-NPR a weak anion exchanger, was 3.5 cm long and 4.6 mm in diameter packed with non-porous resin beads 2.5 ji in diameter. Thus, the maximum efficiency available at the optimum mobile phase velocity would be about 7,000 theoretical plates. The sample was a crude hexokinase product and an... 

Amino -(CHj),NH2 Normal, reversed phase and weak anion exchanger... 

Dizdaroglu, M., Krutzsch, H. C., and Simic, M. G., Separation of angiotensins by high-performance liquid chromatography on a weak anion-exchange bonded phase, Anal. Biochem., 123, 190, 1982. 

NP, WP, P = non polar, weakly polar, polar, respectively SCX, SAX, WAX = strong cation, strong anion, weak anion exchanger, respectively. 

Fig. 3.3d(i) shows the chromatogram of the two acids on a weak anion-exchange column. At the pH used, there will be appreciable amounts of each acid in the unionised form, which probably accounts for the poor shape of the peaks. Addition of an organic solvent to the mobile phase, (ii), greatly decreases the retention and also alters the selectivity. 

A flow injection optical fibre biosensor for choline was also developed55. Choline oxidase (ChOX) was immobilized by physical entrapment in a photo-cross-linkable poly(vinyl alcohol) polymer (PVA-SbQ) after adsorption on weak anion-exchanger beads (DEAE-Sepharose). In this way, the sensing layer was directly created at the surface of the working glassy carbon electrode. The optimization of the reaction conditions and of the physicochemical parameters influencing the FIA biosensor response allows the measurement of choline concentration with a detection limit of 10 pmol. The DEAE-based system also exhibited a good operational stability since 160 repeated measurements of 3 nmol of choline could be performed with a variation coefficient of 4.5%. 

Strata- Primary and secondary amine- Weak anion exchange and Nucleotide phosphates (95)... 

Hence an ion-exchange resin cannot be used at a pH that suppresses the ionization of the group, and weak anion exchange resins, for instance, are only effective over the pH range 2-8. The stronger acids and bases, however, are capable of being used over almost the whole pH range. 

The cinchona alkaloid-based CSPs are actually mixed-mode RP/weak anion-exchange phases and HILICAVAX phases, respectively. The surface layer of these... 

Nogueira, R., Lubda, D., Leitner, A., Bicker, W, Maier, N.M., Lammerhofer, M., and Lindner, W, Silica-based monohthic columns with mixed-mode reversed-phase/weak anion-exchange selectivity principle for high-performance liquid chromatography, J. Sep. ScL, 29, 966, 2006. 

Several research groups, for instance, reported on the generation of weak anion exchanges by reacting the epoxy functionalities with diethylamine [54-57], The resulting diethylaminoethyl monoliths—which are commercially available as CIM (Convective Interaction Media) in disk and column format—have frequently been used for protein and oligonucleotide separation [58] as well as for the purihcation of proteins and plasmid DNA [59-61]. 

Polymethacrylate Weak anion exchanger (tertiary amine) ProSwift WAX Dionex Corporation 50x4.6mm 50x 1 mm Ion exchange chromatography of proteins... 

Separation and purification chromatography has to be applied before the quantitative chromatography. Some purification techniques applied are lEC, such as DEAE-Sephadex A-25 [571], weak anion-exchange column [572,573], strong anion-exchange column (564), cation-exchange column... 

Methylbutanoates and methylbutyl esters are essential flavour compounds in fruit flavours they can be produced biotechnologically as mentioned before. Chowdary et al. [33] have described the production of a fruit-like flavour isoamyl isovalerate by direct esterification of isoamyl alcohol and isovaleric acid in hexane with the help of Mucor miehei lipase immobilised on a weak anion-exchange resin. 

WAX (weak anion exchange). Water only, retention and resolution are modified by pH and ionic strength Ionic compounds. 

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