Peptide reference · Synthetic hexapeptide (contains non-standard residues)
GHRP-2 COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a GHRP-2 Certificate of Analysis. The theoretical average molecular weight of GHRP-2 is 817.97 Da and the monoisotopic mass is 817.428 Da.
Check a GHRP-2 COA nowGHRP-2 reference data
| Name | GHRP-2 |
|---|---|
| Also known as | Pralmorelin, KP-102 |
| Type | Synthetic hexapeptide (contains non-standard residues) |
| Molecular formula | C45H55N9O6 |
| Average molecular weight | 817.97 g/mol (Da) |
| Monoisotopic mass | 817.4275 Da |
| Residues | 6 |
| Sequence | D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH₂ |
| Reference source | PubChem CID 6918245 (formula and mass cross-checked) |
Expected mass spectrometry ions
A GHRP-2 COA may list one of these m/z values instead of the neutral mass. That is still consistent with GHRP-2. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+H]+ | 818.43 | 818.98 |
| [M+2H]2+ | 409.72 | 409.99 |
| [M+3H]3+ | 273.48 | 273.66 |
What else can show up on a GHRP-2 COA
Masses calculated from GHRP-2'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) | 839.41 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) | 855.38 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 931.42 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
| M + 16 (oxidation) | 833.42 Da | Oxidation of Trp |
| M + 0.98 (free acid) | 818.41 Da | C-terminal amide hydrolysed or free-acid synthesis error |
Deletion sequences (5): one residue missing
| Signal | Value | What it means |
|---|---|---|
| des-Ala (M − 71.04) | 746.39 Da | Deletion sequence missing one Ala |
| des-2Nal (M − 197.08) | 620.34 Da | Deletion sequence missing one 2Nal |
| des-Trp (M − 186.08) | 631.35 Da | Deletion sequence missing one Trp |
| des-Phe (M − 147.07) | 670.36 Da | Deletion sequence missing one Phe |
| des-Lys (M − 128.09) | 689.33 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-2 (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-2-specific things to watch
GHRP-2 (pralmorelin) is a six-residue amidated peptide with D-2-naphthylalanine, about 818.0 Da.
It is often sold alongside GHRP-6 and hexarelin. Their masses (818, 873 and 887 Da) are distinct enough that any competent MS result clearly identifies which one you have.
Expect [M+H]⁺ near 818.4 m/z and [M+2H]²⁺ near 409.7 m/z.
GHRP-2 has one tryptophan, so a +16 Da peak (near 833.4 Da monoisotopic) signals oxidation. A free C-terminal acid instead of the amide is only 0.98 Da heavier and needs high-resolution MS to see.
It shares its D-2-naphthylalanine, D-phenylalanine and amidated lysine with ipamorelin, but is about 106 Da heavier (818.0 vs 711.9 Da). A deletion of D-2-Nal gives about 620.3 Da.
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 6918245: GHRP-2 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
Is pralmorelin the same as GHRP-2?
Yes. Pralmorelin is the generic name for GHRP-2, about 818.0 Da average.
What does a GHRP-2 peak near 833 Da mean?
Oxidized tryptophan (+16 Da).
How is GHRP-2 different from ipamorelin by mass?
GHRP-2 is about 818.0 Da and ipamorelin about 711.9 Da, roughly 106 Da apart.
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.