[Kaladiscope]

Hi Colleagues,

I am having some troubles in order to isolated my peptide, which it has incorporated a PEG derivative in one of the side chain. The problem is that the reaction partner (PEG-compound) its overconcentrated (300 eq) and my peptide is just only 50 micrograms, which make impossible to see anything in the UV chromatogram and then make impossible to collect any peak in the HPLC preparative. I tried several times but I didn't have any success. Therefore I was thinking in other strategies. Liquid-liquid extraction would be an idea. But since both are really polar compounds (both have PEG and PEG is really well soluble in water or any polar solvent) I don't think that this is a good idea.

Any suggestion?