[silentelysium]

I'm currently synthesising a 34 amino acid polypeptide on Wang linker-PV/DVB resin and the first peptide I synthesised had a lot of impurities. The crude yield was adequate but the purified protein was very low. I also noticed there was a lot of by products or fragments from the synthesis (as shown on mass spec). I'm thinking the high amount of by product maybe due to the resin (PS-DVB) and opted to use a PEG-PS resin.It may also be my protocol:

0.1mmol scale
Fmoc-AA: 4 aq.
HBTU: 4 eq
DIPEA: 10 eq.
Using 20% piperidine

Is the resin really the problem or how I synthesis my peptide? If you have any suggestions, is there a reference to it?

Thanks very much!