extra GPC peak Dialysis tube

[parparak]

I see negative peaks which come out aftre my main peak in the GPC chromatogram ( RI detector) in case of my dialyzed samples but not the non-dialyzed ones. I wonder whether these peaks may stem from dialysis tube? ( cellulose tube, 12 kD)

Thanks in advance

[danko]

What you see is probably the total inclusion volume/disturbance.
The dialyzed sample solution is more different from the mobile phase than the non-dialyzed solution (the dialysis has removed the majority of small molecules from the solution). Actually this is more usual than cases with no negative peak at the total inclusion retention time.

Best Regards