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 50 mg Copper Peptide Research Grade PRG The copper(II) binding tripeptide GHK, a valuable crystallization and phasing tag for macromolecular crystallography GHK Cu as a multifunctional copper peptide: synthesis routes, process engineering and emerging applications Systems Microbiology and Biomanufacturing Springer Nature Link Theoretical study of copper binding to GHK peptide ScienceDirect GHK Cu 50mg Copper Peptide Research Spartan Peptides