Pyridine-based Anion Exchangers

[Phraldo]

Does anyone know of a commercially available really weak anion exchanger? I want to purify or enrich a polyanionic (-5 charge), relatively high molecular weight compound by exchange onto a resin at about pH 5 followed by wash-out of unretained or weakly retained impurities, then strip the concentrated product off by upward adjustment of pH to "neutralize" exchange capacity of the support, BUT the compound is unstable above pH8.5 (so DEAE is out). It seems to me that a pyridine-based exchanger would be ideal for this purpose. I have not been able to find this type of exchanger except for Amberlite IR-4B but it has been discontinued.

[SIELC_Tech]

What anionic groups do you have: phosphates, sulphates or carboxylic acids? If it is carboxylic acid what is pKa of acidic groups? Are you looking into SPE columns or HPLC?
We have anion-exchange mixed mode phase with pKa of 7.

regards,

Vlad

[Phraldo]

Thanks for your prompt response to my inquiry. The ionic groups are aromatic sulfonates. I only need a low resolution (high capacity) column in essentially SPE mode. The support should be compatible with mixed aqueous organic solvents (MeOH or acetonitrile). Compound molecular weight is about 3000. What support would you recommend?

[SIELC_Tech]

Phraldo,

We are working on sulfonated surfactants with various number of acidic groups. It is a complex mixture of isomers. We were able to group them in "bundles".
Please contact me via email to discuss (you can call us if you want to talk about this application):

http://www.sielc.com/AboutUs_ContactUs.html

regards,

Vlad