Your copper peptide product should be this exact blue. If it isn't, you already have your answer. GHK Cu is blue because of coordination chemistry, not dye. The Cu ion at the center Theoretical study of copper binding to GHK peptide ScienceDirect Coordination geometry of the copper(II) peptide core obtained by QM MM Download Scientific Diagram Buy GHK Cu 50mg & 100mg Copper Tripeptide Koi Peptides Theoretical study of copper binding to GHK peptide ScienceDirect