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 GHK Cu Engage Peptides GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link China Copper Peptide(GHK Cu) CAS:89030 95 5 Manufacturers Free Sample Alfa Chemical RCSB PDB 6QUG: GHK tagged MBP Nup98(1 29)