GHK-Cu is the copper complex of glycine-histidine-lysine, a tripeptide usually listed in cosmetic ingredient catalogues as Copper Tripeptide-1. Its registry number is CAS 89030-95-5, its molecular formula C14H21CuN6O4 and its molecular weight 400.91. It is supplied as a blue powder, and that colour is a useful first check: the free peptide GHK is a different substance with a different registry number. One condition matters before any comparison: identifiers describe what a material is, while the release limits that bind both parties are the ones on the signed batch COA.
Which number belongs to which substance?
CAS 89030-95-5 identifies the copper complex. CAS 49557-75-7 identifies free GHK, the tripeptide without copper. We have seen both numbers used on pages headed GHK-Cu, so we ask buyers to put the number into the enquiry rather than relying on the product title. If a quotation arrives with 49557-75-7 on a blue powder described as a copper complex, the document and the description disagree and should be reconciled before a sample is ordered.
What does molecular weight tell you about a quotation?
It gives you a reproducible cross-check. C14H21CuN6O4 at 400.91 implies that one millimole of the complex is about 0.401 g. Suppose a formulation brief calls for 0.05 mmol in a 100 g laboratory batch: that is roughly 20 mg of the complex. If a supplier's suggested inclusion of 2 g is being compared against that brief, the two figures differ by a factor of 100. These are illustrative arithmetic, not a specification or a suggested inclusion rate; the point is that a buyer who can do the conversion will notice a unit error before it reaches a batch record.
Why do we ask which method produced the number?
Because identity and assay are method-dependent. HPLC with a stated column, gradient, wavelength and integration rule is a different measurement from an LC-MS identity trace. Ask for both: the LC-MS or MS trace against the theoretical value, and the assay method with its calculation basis. Two offers are only comparable once the method and the basis match.
What should be on the check sheet?
Check: registry number, sequence, molecular formula and weight, appearance, copper complex confirmation, solubility in the intended matrix, storage and the document list. What to confirm: which of these are stated on the batch COA, which method supports each result, and which limits are agreed before a sample ships. Our own quick-spec block follows exactly this order.
Which documents should travel with the sample?
Ask for the COA, MSDS, TDS and any analytical report your destination market requires, and have the document list written into the quotation. A sample approved against one method should be re-ordered against the same method.
What should you avoid assuming?
Do not assume that a catalogue purity figure, a two-year shelf life, a minimum order or a certificate badge applies to your order. Those are supplier-specific commitments. We state them per order, not in the catalogue, and we do not describe finished-product performance.
References
[1] CAS Common Chemistry, entries 89030-95-5 and 49557-75-7. [2] INCI naming convention, Personal Care Products Council. [3] General practice for peptide identity confirmation by mass spectrometry and chromatographic assay.
Request the documentation
See our GHK-Cu product page for the full 15-item identifier block, then email sales@yaxbio.com to request a COA, a sample or a bulk quotation.