I have synthesized a seven amino acid sequence having a C-terminal amide Phe-Aib-Leu-Ala-Aib-Leu-Phe-NH2 by Rink amide resin. I have got the mass spectrometry done and somehow the peptide didn't form. When I tried to do the cleavage by 10% TFA in DCM in absence of any scavenger I got a pink color solution. Then I have performed the global deprotection in 95% TFA, 2.5% H20 and 2.5% Triisopropylsilane. And then evaporation of TFA, lyophilizing it in H2O, precipitating in ice-cold ether. What can be the problem in terms of synthesis procedure?

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