Guide
How to check a GHK-Cu batch: colour, copper ratio, CAS and the COA, line by line
Published October 7, 2026 · Facts checked October 9, 2026
Short answer
A genuine GHK-Cu batch is blue, its COA carries CAS 89030-95-5 and the batch number of the vials you receive, MS confirms the peptide, and its copper content fits its form: the pure 1:1 complex is 15.81 % copper. Divide copper moles by peptide moles and you get the Cu²⁺ : peptide ratio — about 1.0 for a 1:1 batch. HPLC purity alone shows none of this.
1. The header: is this COA about your batch?
- Product name, with an alias you recognise (Copper Tripeptide-1, prezatide copper).
- CAS 89030-95-5. If it says 49557-75-7, the document describes copper-free GHK.
- A batch number that matches your vials or kit, and a test date.
- Who issued it: the supplier's QC or an independent laboratory, named.
Sources: PubChem CID 71587328 · PubChem CID 73587
2. Appearance
GHK-Cu is blue: the colour is the copper(II) bound in the peptide. A white or off-white powder labelled GHK-Cu contains no bound copper.
3. Identity by mass spectrometry
ESI-MS confirms the peptide. It answers 'is this GHK?' — not 'how much copper is bound?'.
4. HPLC purity — and what it is not
HPLC purity is the peptide peak's share of the peptide-related signal. It says nothing about copper, acetate or water, so a 99 % HPLC purity can sit on a powder that is far from 99 % GHK-Cu. Read it next to the content lines.
5. Peptide content, water and acetate
These lines explain what the powder is made of as-is. Peptide salts usually carry acetate and some water, which is why as-is copper and peptide percentages are below the theoretical figures for the pure complex.
6. Copper content and the Cu²⁺ : peptide ratio
Copper by ICP-OES, ICP-MS or AAS gives total copper as a mass percentage. The pure 1:1 complex is 15.81 % copper (63.546 / 401.91); the 2:1 form is 8.56 %.
Ratio = (copper % ÷ 63.546) ÷ (peptide % ÷ 340.38). Illustrative numbers, not a Cupratec batch: 14.0 % copper and 75.0 % peptide give (0.2203) ÷ (0.2203) = 1.00, one copper per peptide. Below 1, part of the peptide carries no copper; above 1, there is more copper than the 1:1 site can hold.
Sources: PubChem CID 165429100 · PubChem CID 9831891 · PubChem CID 73587 · Trapaidze et al., J Biol Inorg Chem 2012
Calculator
Cu²⁺ : peptide ratio from your COA
Enter copper content and peptide content as percentages (0–100).
7. UV-Vis
A broad band near 605–606 nm near neutral pH is the copper(II) in GHK's binding site. A band near 816 nm points to uncomplexed aqua copper; a band near 565 nm means another ligand such as imidazole has joined the copper.
Sources: Bossak-Ahmad et al., Int J Mol Sci 2020 · Ufnalska et al., Inorg Chem 2021
Red flags
- GHK-Cu offered with CAS 49557-75-7.
- A white 'GHK-Cu'.
- No batch number, or one that does not match your vials; one report reused for every batch.
- HPLC purity is the only number on the page.
- Copper far above 15.81 % for a 1:1 batch, or a ratio well away from the form you ordered.
- A 100.0 % result with no method named.
Sources: PubChem CID 71587328 · PubChem CID 73587 · PubChem CID 165429100
What a Cupratec batch COA contains
Each batch of GHK-Cu and AHK-Cu has its own COA with the batch number, reporting HPLC purity, MS identity, bacterial endotoxin and fill. Copper content, the Cu²⁺ : peptide ratio, UV-Vis, water and acetate are available on request and agreed before the quote.
Questions
- How do I know if GHK-Cu is real?
- Check that it is blue, that the COA shows CAS 89030-95-5 and the batch number of your vials, that MS confirms the peptide, and that the copper content and Cu²⁺ : peptide ratio fit the form you ordered (15.81 % copper and a ratio of about 1.0 for the pure 1:1 complex).
- How do I calculate the Cu²⁺ : peptide ratio from a COA?
- Divide the copper percentage by 63.546 and the peptide-content percentage by 340.38 (the molecular weight of GHK), then divide the first result by the second. 1.0 means one copper per peptide.
- Is HPLC purity enough for GHK-Cu?
- No. HPLC purity measures the peptide signal only. Copper content, peptide content and ideally UV-Vis show what share of the powder is the copper complex.
- What copper percentage should GHK-Cu have?
- The pure 1:1 complex is 15.81 % copper and the 2:1 form 8.56 %. Real batches read lower because of acetate and water, so judge copper together with peptide content through the ratio.
References
- PubChem CID 71587328 — prezatide copper (CAS 89030-95-5) — CAS 89030-95-5 belongs to the copper complex; PubChem records it as the singly protonated form, 402.92 g/mol
- PubChem CID 73587 — glycyl-L-histidyl-L-lysine (C14H24N6O4, 340.38) — GHK identity, formula and molecular weight
- PubChem CID 165429100 — GHK copper complex (C14H22CuN6O4, 401.91) — formula and molecular weight of the neutral 1:1 complex
- PubChem CID 9831891 — bisprezatide copper (C28H46CuN12O8, 742.3) — the 2:1 peptide-to-copper record
- Trapaidze et al., J Biol Inorg Chem 2012 — Cu²⁺ binding to DAHK and GHK by ITC — 1:1 stoichiometry; conditional Kd 7.0 × 10⁻¹⁴ M at pH 7.4
- Bossak-Ahmad et al., Int J Mol Sci 2020 — ternary Cu(II) complex with GHK — d–d band of Cu(GHK) at 605–606 nm; aqua copper absorbs near 816 nm
- Ufnalska et al., Inorg Chem 2021 — reduction of Cu(II)GHK by glutathione — Cu(II)GHK d–d band at 606 nm; imidazole adduct at 565 nm; glutathione reduces the complex
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