http://www.bio-rad.com/webroot/web/pdf/ps/literature/biopharm_article.pdf

Article Affinity purification of IgM using a novel synthetic ligand

Article Comparison of mono Q, superose-6, and ABx fast protein liqui...

Dear Doctor Al-saadi,

thank you so much for your reply and the attached articles.

I will have a look at at them.

In the meantime I found a review that presents a very nice overview about IgM purification techniques, their advantages and disadvantages:

Article Immunoglobulin-M purification - Challenges and perspectives

I would also recommend looking up IgM Capture Select (you can just type it in the google and check what comes up) and thiophilic adsorbtion chromatography.