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 Peptide Research Spartan Peptides GHK Cu Copper Tripeptide 1 Research Reagent GHK Cu 50mg PeptideX Research Is Less More? Influence of the Coordination Geometry of Copper(II) Picolinate Chelate Complexes on Metabolic Stability Inorganic Chemistry Theoretical study of copper binding to GHK peptide ScienceDirect