With 4 carboxylic acids per molecule and one primary amino group, fumonisins may not bind very well to SP Sepharose, a cation exchange resin. They probably bind better to an anion exchange resin such as QAE Sepharose. The pH should be kept high enough to make sure the carboxylic acids are deprotonated. The compound could be eluted with increasing salt, or decreasing pH.

Dear Dr Adam, Thank you very much for your advice.