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 Copperbiomolecule complexes in the gas phase. The ternary way Tureek 2007 Mass Spectrometry Reviews Wiley Online Library GHK Cu 50 mg Copper Peptide Research Grade PRG Is Less More? Influence of the Coordination Geometry of Copper(II) Picolinate Chelate Complexes on Metabolic Stability Inorganic Chemistry