counterion

Peptide Purity Testing: Why 99% Differs on a Tripeptide and a 44-mer

At 99% per coupling a tripeptide comes off the resin 98% correct and a 44-residue chain comes off at 65%. What had to be removed, why deletion sequences are the hardest impurity to separate, and the trifluoroacetate counterion that is in the vial and not on the paperwork.