Although CPC Scientific created a peptide with 130 amino acids, generally speaking, peptides with more than 30 amino acids can cause issues. Since HPLC is carried out in solution, solubility is one of the most crucial factors to take into account when developing a peptide as it will affect the purity reached. The peptide becomes less soluble as the number of hydrophobic residues increases in the sequence. A few sequences can aggregate as well, which will make manufacturing harder. CPC is available to answer any queries and has designed over 100,000 peptides, so we have plenty of experience.