The copper peptides have a research literature of their own, centred on skin and hair rather than on the systemic models the rest of the catalogue is studied in. GHK-Cu — the tripeptide glycyl-L-histidyl-L-lysine complexed with copper(II) — was first isolated from human plasma and has been examined for decades in wound-closure, collagen-synthesis and matrix-remodelling models; it is the compound most cosmetic peptide formulations are built on. AHK-Cu is the alanyl-histidyl-lysine analogue, studied principally in hair-follicle models.
A copper peptide certificate carries one figure a plain peptide’s does not: the copper content, reported separately from the peptide content, because the complex is the product and a lot that is short on copper is short on the product. Both are published for every lot here, with purity and the batch code printed on the vial. The blends that include GHK-Cu (GLOW, KLOW) are shelved with the peptides, since they are studied as repair blends rather than cosmetics.
GHK-Cu is distinctly blue in solution and the colour is a rough identity check, not a purity one; the certificate is the purity check. Supplied strictly as laboratory research materials, shipped within Canada.