Ion Exchange Chromatography (IEC) Beads

Note: bead size is 50-150 μ for all ion exchange products; also, agarose concentration is either 4% (A-4B) or 6% (A- 6B) as indicated.

Reference Brand Name & Price BioScience Bead Equivalent (code) Settled Bead Volume Catalog Number BioScience Bead Price Target Application(s)
Sigma DCL-6B-100 DEAE Agarose A-6B-CL-OR; R= Diethylaminoethyl; (DEAE) Anion exchange
$60/50 ml 50 ml DEAE-A-0601-0050 $42.00
$100/100 ml 100 ml DEAE-A-0601-0100 $70.00
$325/500 ml 500 ml DEAE-A-0601-0500 $228.00
> 500 ml Inquire Inquire
Sigma CCL-6B-100-CL; Carboxymethyl Agarose A-6B-CL-OR;
R = OCH2CO2Na ; Sodium Carboxymethyl (NaCM)
Cation exchange
$67/50 ml 50 ml NaCM-A-0601-0050 $47.00
$112/100ml 100 ml NaCM-A-0601-0100 $78.00
$353/500ml 500 ml NaCM-A-0601-0500 $247.00
> 500 ml Inquire Inquire
No commercial counterpart Crosslinked Na/Ca Alginate; poly-mannuronic-guluronic acids linked B-(1-->4) Cation exchange
50 ml LG-0301-0050 $47.00
100 ml LG-0601-0100 $78.00
500 ml LG-0301-0500 $247.00
>500 Inquire Inquire
Sigma A-1018; CNBr-attached L-arginine to 6% Agarose A-6B-CL-OR;
R = CH2CH2NH-Arginine ; (Arg)
Zwitterionic bead
$157/5ml 5 ml Arg-A-0601-0005 $110.00
$522/25 ml 25 ml Arg-A-0601-0025 $365.00
> 25 ml Inquire Inquire
Sigma S-1799; SP-Sepharose® C-4MB-CL-OR; R=OSO3Na;
C= carrageenan ; (NaCgn)
10 ml C-0401-0010 $40.00 Cation exchange; also virus and protein interaction
50 ml C-0401-0050 $70.00
$154/100ml 100 ml C-0401-0100 $108.00
$518/500ml 500 ml C-0401-0500 $363.00
> 500 ml Inquire Inquire
See Also :
Anionic wax hydrophobic beads
Cationic wax hydrophobic beads

A=Agarose; 4 or 6 = % Agarose in gel bead; CL=crosslinked; R= ether-linked substituent or derivative; CM = carboxymethyl

EC Theory & Practice

Biological materials generally contain functional groups or moieties that can have either a net positive or net negative charge depending on the pH of the medium in which they’re present. Proteins, for example, consist of amino acids (AA’s) which are either basic, acidic or neutral. Most proteins therefore typically have a pH at which the postively charged AA’s are balanced by the negative AA’s and hence the protein is “isoelectric” or has reached its isoelectric point (pI) at that pH.

IEC is predicated on the fact that opposite charges attract and negative charges repel one another. Thus, to give a protein a net positive charge one could lower the pH below pH 7 so that basic amino acids having terminal amines or similar basic moieties would become protonated and hence positively charged. Lowering the pH below 7 would also push the equilibrium of acidic AA’s and their free carboxyl groups toward the protonated carboxylic acid-as opposed to the ionized form that would predominate at higher pH’s. Similarly, raising the pH above the pKb of the basic amino acids would render them unprotonated and hence neutral while making all the acidic AA’s ionized and hence negative charges.

When separating a mixture of proteins, one chooses a pH which will SELECTIVELY render a charge (either positve or negative) on their target protein which is OPPOSITE to that of the bead matrix they’ve chosen to do the separation. As a result, the target protein is either selectively retained on the bead matrix (ie. column) or is adequately separated from all other mixture components based on relative affinity for the IEC matrix. Achieving such separation allows for collection of the target protein free of other components in the original mixture.

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