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 50mg Copper Tripeptide Research Compound 99% N2 (N Glycyl L histidyl) L lysinato(2 )]copper 89030 95 5 wiki GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link