Porous Anion Exchangers

The major anion exchangers for ion chromatography are based on two substrate types macroporous and microporous (or gel type) materials. Microporous resins were formerly popular because of their superior ion-exchange kinetics. However, microporous substrates can be spongy. Columns packed with this material may eventually undergo bed compression leading to reduced column performance. 

The substrate polymer beads used in this work are quite hard and do not swell and shrink when the solvent is changed. A measure of bead hardness is given by the swelling propensity value. This value is obtained by measuring the backpressure of a column with a tetrahydrofuran mobile phase and then with an aqueous 

An SP value of zero indicates nonswelling material. The substrate used in this work had an SP of 0.8. Many PS-DVB resins have SP values well above 1.0. Columns packed with the AN 1 resin have given excellent separations of common anions using a variety of eluents. 

Polymeric resins from Hamilton have been used extensively for anion chromatography. Their PS-DVB anex resins contain trimethylammonium groups. 

PRP XlOO and PRP XI10 have exchange capacities of 0.19 and 0.11 mequiv g respectively. Their RCXIO has a somewhat higher capacity 0.35 mequiv g . All of these have an average pore size of 100 A. Good separations of anions have been obtained with a variety of eluents [9]. However, these resins are quite hydrophobic. For this reason, the eluents often contain -7.5% methanol or -0.1 mM sodium thiocyanate to give better peak shapes. 

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N. Kubota, Y. Konno, K. Saito, K. Sugita, K. Watanabe and T. Sugo, Protein Adsorption and Elution Performances of Modules Consisting of Porous Anion-Exchange Hollow-Fiber Membranes, Maku, 22 (1997) 105. 

K. Sunaga, M. Kim, K. Saito and K. Sugita and T. Sugo, Characteristics of Porous Anion-Exchange Membranes Prepared by Cografting of Glycidyl Methacrylate with Divinyl Benzene, Chem. Mater., in press. 

Pantazaki, A., Baron, M. H., Revault, M. and Vidal-Madjar, C., Characterization of human serum albumin adsorbed on a porous anion-exchange support, J. Colloid Interface Sci., 207, 324, 1998. 

According to a recent publication, the separation of protein and plasmid DNA as well as that of DNA and lipopolysaccharides is possible by displacement chromatography. Linear polyacrylic acid (Os-type, Mw 5100 g/mol) was successfully used as displacer. A particularity was the fact that conventional stationary phase materials based on porous anion exchanger or... 

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... 

Figure 6, High pressure liquid chromatogram of creatine kinase isoenzymes. First peak, MM second peak, BB. Conditions 50 cm X 4.8 mm (i.d.) column with yydac porous layer bead anion exchange mobile phase, step gradient Solvent A, 10 mmol/liter Tris buffer, pH 8.3 solvent B, 10 mmol/liter Tris buffer, pH 7.0,0.5 mol KCl flow rate, 2 ml/min detection, collected fractions assayed (45).

Alpert, A. J. and Regnier, F. E., Preparation of a porous microparticulate anion-exchange chromatography support for proteins, /. Chromatogr., 185, 375,1979. 

Effect of porous structure of the SMC on resolution in chromatography of proteins Theoretical aspects Anion Exchange disks [75]... 

A good general-purpose anion-exchange column for non-suppressed applications is the Hamilton PRP-XlOO column. As the selection of eluents used with this column is quite varied, the reader is referred to Hamilton column literature for specific eluent recommendations. The Hamilton PRP-XlOO column is most likely prepared via chemical modification of a porous polymeric substrate. 

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