You can try sephadex column

If they have different MW

Or you can try column of fine silica if they are not phenolics

In addition of the comments above, usually, if we have only a small amount of samples we did TLC preparative (also HPLC preparative). Maybe you can try search in the Camag TLC data base the best TLC conditions, who knows you can find nicer method. Best regards

http://www.camag.com/en/tlc_hptlc/customer_magazine_cbs/ccbs_database.cfm

Dear Drs.

thanks for your suggestions.

I tried sephadex but they elute together, probably they have very close Mwt.

i'll try the other suggestions if I can find the facilities.

thank you so much