Peptide reference · Copper complex of the tripeptide GHK
GHK-Cu COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a GHK-Cu Certificate of Analysis. The theoretical average molecular weight of GHK-Cu is 340.38 Da and the monoisotopic mass is 340.186 Da.
Check a GHK-Cu COA nowGHK-Cu reference data
| Name | GHK-Cu |
|---|---|
| Also known as | Copper tripeptide-1, Prezatide copper, Glycyl-L-histidyl-L-lysine copper |
| Type | Copper complex of the tripeptide GHK |
| Molecular formula | C14H24N6O4 |
| Average molecular weight | 340.38 g/mol (Da) |
| Monoisotopic mass | 340.1859 Da |
| Residues | 3 |
| Sequence | Gly-His-Lys (complexed with Cu²⁺) |
| Reference source | PubChem CID 73587 (GHK); CID 71587328 (prezatide copper) (formula and mass cross-checked) |
Also accepted: GHK copper complex, cationic form (prezatide copper): C14H23CuN6O4, 402.92 Da average / 402.108 Da monoisotopic.
The primary reference mass is the free GHK peptide (340.38 Da), because copper often dissociates during analysis. A mass near 401–403 Da indicates the intact copper complex and is also acceptable.
Expected mass spectrometry ions
A GHK-Cu COA may list one of these m/z values instead of the neutral mass. That is still consistent with GHK-Cu. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+H]+ | 341.19 | 341.39 |
| [M+2H]2+ | 171.10 | 171.20 |
| [M+3H]3+ | 114.40 | 114.47 |
What else can show up on a GHK-Cu COA
Masses calculated from GHK-Cu's formula and sequence for the adducts, degradation products and synthesis impurities a lab report can show. A match tells you what the extra peak probably is.
| Signal | Value | What it means |
|---|---|---|
| Na adduct, deconvoluted (M + 21.98) | 362.17 Da | Sodium adduct: an MS artifact, not a separate impurity. The [M+Na]+ ion itself is at M + 22.99 |
| K adduct, deconvoluted (M + 37.96) | 378.14 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 454.18 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
Deletion sequences (3): one residue missing
| Signal | Value | What it means |
|---|---|---|
| des-Gly (M − 57.02) | 283.16 Da | Deletion sequence missing one Gly |
| des-His (M − 137.06) | 203.13 Da | Deletion sequence missing one His |
| des-Lys (M − 128.09) | 212.09 Da | Deletion sequence missing one Lys |
Adduct rows are deconvoluted masses (the shift seen against [M+H]+); the singly charged [M+Na]+ ion itself sits at M + 22.99. Deletion masses alone can't say which copy of a repeated residue is missing.
Short peptides like GHK-Cu (3 residues) are easy to make cleanly, so 98% HPLC purity should be the floor, not the goal. The full checklist is in how to read a peptide COA.
GHK-Cu-specific things to watch
GHK-Cu is a complex of the tripeptide Gly-His-Lys with a copper(II) ion. Depending on the ionization method and how the lab reports it, the mass spectrum may show the free GHK peptide (about 340.4 Da) or the copper-bound species (about 401–403 Da). Both are consistent with genuine GHK-Cu.
A well-made GHK-Cu powder is distinctly blue. A COA should identify the copper content or confirm the complex, not just the peptide. A white powder sold as GHK-Cu deserves a question to the vendor.
Because it is only three residues, HPLC purity for GHK-Cu is usually very high (99%+). A purity figure in the low 90s is a meaningful warning for such a simple molecule.
Compounds with similar mass
If a COA's mass is off, compare it with these neighbors. A match to one of them can point to a mislabeled product.
- Epitalon: 390.35 Da (+49.97 Da)
- SS-31 (Elamipretide): 639.79 Da (+299.41 Da)
- NAD+: 663.43 Da (+323.05 Da)
Sources
- PubChem CID 73587 (GHK); CID 71587328 (prezatide copper): GHK-Cu formula and reference mass.
- CIAAW: Standard atomic weights: Used to calculate average molecular weights.
- NIST CODATA: proton mass: Used to convert m/z charge states to neutral mass.
- PeptideCOACheck methodology: How the checker's thresholds work.
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Frequently asked questions
What is the molecular weight of GHK-Cu?
The average molecular weight of GHK-Cu (C14H24N6O4) is 340.38 Da and its monoisotopic mass is 340.1859 Da, calculated from the molecular formula and cross-checked against PubChem CID 73587 (GHK); CID 71587328 (prezatide copper).
What other masses can show up on a GHK-Cu COA?
Besides the main peak, a GHK-Cu COA can show a sodium adduct (deconvoluted mass near 362.17 Da). The table on this page lists every expected variant with its mass.
For laboratory research use only. This page describes analytical chemistry data. It is not medical advice and makes no claim about effects in humans or animals.