Any suggestion on what size exclusion column I should use for separation of a small molecule (~400 Da) and a ball-shaped molecule (~2000 Da)? I tried TSK-Gel super SW 2000 4.6x30cm, 4u, 120A column. It didn't work. The lower side cut-off of this column is 1000 Da for dextrans and 5000 Da for globular proteins. As the 2000 Da molecule I have to separate is ball-shaped, the column didn't work well for this separation.

Could somebody who has experience with small molecule size exclusion give me a suggestion?

Thanks.