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II. SERVACEL^® Cellulose Ion Exchangers

In contrast to the above mentioned resin based exchangers, cellulose ion exchangers have a very loose hydrophilic network (no pores) with well separated charged groups. Ionic macro(bio)molecules are adsorbed to only a few sites which can be desorbed selectively under extremely mild conditions with high recoveries. pH stability is excellent between 3 an 12.

In order to provide greater stability and pressure resistance, the cellulose matrix can be produced in "regenerated" microcrystalline form. Here, the  particles are microgranular and the amorphous (fibrous) part of the cellulose fibers is largely removed.

Compared to fibrous material, microgranular exchangers are structurally more reproducible, allow a more dense packing, have faster kinetics and higher capacity. Fibrous exchangers have much higher flow rates under standardized conditions of pressure and column dimensions; on the other hand, the resolving power is much lower: to obtain a comparable separation result as with microgranular material, a column of more than double  the length will be necessary.

CM and DEAE types are the most frequently used cellulose ion exchanger.

CM Cellulose is a cation exchanger (acidic type): Cellulose is derivatized with CarboxyMethyl-chloride. The resulting weakly acidic high capacity exchanger is used for the separation of neutral and basic proteins and peptides (below their isoelectric point).

DEAE Cellulose is an Anion exchanger (basic type): DiEthylAminoEthyl-groups are covalently bound to the cellulose hydroxylic groups.  The anion exchanger can be applied for the chromatography of proteins with neutral or acidic isoelectric points (IP): separation must occur above their IP, which can easily be determined by isoelectric focusing electrophoresis (IEF). Serum components, enzymes, peptides, polysaccharides, RNA-types, viruses, lipids, and ribosomes have been separated. DEAE-cellulose is also suitable for purification of nucleic acids.
SERVACEL^® CM 52 and DEAE 52 are microgranular and supplied in pre-swollen form to facilitate handling: they are ready-to-use after equilibration with the selected buffer system. They do not require the time consuming "precycling" procedure (washing with acid resp. alkali), which is necessary for dry cellulose ion exchangers , to swell the material in a reproducible manner and release the full capacity.