Peptide reference · Synthetic hexapeptide
GHRP-6 COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a GHRP-6 Certificate of Analysis. The theoretical average molecular weight of GHRP-6 is 873.01 Da and the monoisotopic mass is 872.445 Da.
Check a GHRP-6 COA nowGHRP-6 reference data
| Name | GHRP-6 |
|---|---|
| Also known as | Growth Hormone Releasing Hexapeptide |
| Type | Synthetic hexapeptide |
| Molecular formula | C46H56N12O6 |
| Average molecular weight | 873.01 g/mol (Da) |
| Monoisotopic mass | 872.4446 Da |
| Residues | 6 |
| Sequence | His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂ |
| Reference source | PubChem CID 4345065 (formula and mass cross-checked) |
Expected mass spectrometry ions
A GHRP-6 COA may list one of these m/z values instead of the neutral mass. That is still consistent with GHRP-6. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+H]+ | 873.45 | 874.02 |
| [M+2H]2+ | 437.23 | 437.51 |
| [M+3H]3+ | 291.82 | 292.01 |
What else can show up on a GHRP-6 COA
Masses calculated from GHRP-6'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) | 894.43 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) | 910.40 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 986.44 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
| M + 16 (oxidation) | 888.44 Da | Oxidation of Trp |
| M + 32 (double oxidation) | 904.43 Da | Two oxidations, or one Met to sulfone / one Trp to N-formylkynurenine |
| M + 0.98 (free acid) | 873.43 Da | C-terminal amide hydrolysed or free-acid synthesis error |
Deletion sequences (5): one residue missing
| Signal | Value | What it means |
|---|---|---|
| des-His (M − 137.06) | 735.39 Da | Deletion sequence missing one His |
| des-Trp (M − 186.08) | 686.37 Da | Deletion sequence missing one Trp |
| des-Ala (M − 71.04) | 801.41 Da | Deletion sequence missing one Ala |
| des-Phe (M − 147.07) | 725.38 Da | Deletion sequence missing one Phe |
| des-Lys (M − 128.09) | 744.35 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 GHRP-6 (6 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.
GHRP-6-specific things to watch
GHRP-6 is a six-residue amidated peptide, about 873.0 Da, with two tryptophans.
Tryptophan can oxidize (+16 Da, +32 Da), so a main peak shifted upward by 16 Da is a sign of degraded material.
Expect [M+H]⁺ near 873.5 m/z and [M+2H]²⁺ near 437.2 m/z.
With two tryptophans, GHRP-6 can show both single (+16 Da, near 888.4 Da monoisotopic) and double (+32 Da, near 904.4 Da) oxidation. Losing the N-terminal histidine gives about 735.4 Da.
Losing one of GHRP-6's tryptophans leaves a 686.4 Da fragment, the same mass you'd get from hexarelin missing its 2-methyl-tryptophan. Go by the main peak (873.0 vs 887.0 Da) to tell the products apart.
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.
Sources
- PubChem CID 4345065: GHRP-6 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 does 437.2 m/z mean on a GHRP-6 COA?
The [M+2H]2+ ion of the 872.4 Da (monoisotopic) molecule.
What does a GHRP-6 peak near 904 Da mean?
Both tryptophans oxidized, or one tryptophan converted to N-formylkynurenine. Either way it's a sign of degraded material.
How do I tell GHRP-6 from hexarelin on a COA?
By the main mass: about 873.0 Da for GHRP-6 versus 887.0 Da for hexarelin.
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.