Peptide reference · 29-residue GHRH fragment (amidated)
Sermorelin COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a Sermorelin Certificate of Analysis. The theoretical average molecular weight of Sermorelin is 3,357.88 Da and the monoisotopic mass is 3,355.819 Da.
Check a Sermorelin COA nowSermorelin reference data
| Name | Sermorelin |
|---|---|
| Also known as | GRF 1-29 NH2, GHRH (1-29) |
| Type | 29-residue GHRH fragment (amidated) |
| Molecular formula | C149H246N44O42S |
| Average molecular weight | 3,357.88 g/mol (Da) |
| Monoisotopic mass | 3,355.8187 Da |
| Residues | 29 |
| Reference source | PubChem CID 16132413 (formula and mass cross-checked) |
Expected mass spectrometry ions
Electrospray (ESI) mass spectrometers measure mass-to-charge ratio (m/z), so a molecule can show up at several values depending on how many protons it picks up. If a Sermorelin COA lists one of these m/z values instead of the neutral mass, that is still consistent with Sermorelin.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+3H]3+ | 1,119.61 | 1,120.30 |
| [M+4H]4+ | 839.96 | 840.48 |
| [M+5H]5+ | 672.17 | 672.58 |
| [M+6H]6+ | 560.31 | 560.65 |
Calculated from the molecular formula using a proton mass of 1.00728 Da. High-resolution instruments report monoisotopic values. Lower-resolution or deconvoluted results are often closer to the average mass.
What a good Sermorelin COA should show
- Identity by MS: a main mass within about ±1 Da of 3,357.88 (average) or 3,355.82 (monoisotopic), or one of the charge states above, with the spectrum image attached.
- Purity: ≥98% by HPLC (≥99% is excellent), with a chromatogram that shows retention time, peak area and a peak table.
- Traceability: the product name "Sermorelin", a batch/lot number that matches your vial, a test date within the last 12 months, and the name of the testing lab.
- Independence: ideally a third-party lab with a report ID or QR code you can verify.
- Optional extras: net peptide content (actual mg per vial), endotoxin and heavy-metal results.
Sermorelin-specific things to watch
Sermorelin is the native 1-29 fragment of GHRH with a C-terminal amide, about 3357.9 Da. It is only about 10 Da lighter than Mod GRF (1-29), so a low-resolution result can't always tell them apart.
Sermorelin contains a methionine (position 27), which can oxidize. An extra peak at +16 Da in the mass spectrum suggests oxidation; the checker will mention this if your reported mass is about 16 Da high.
Ask whether the lab used high-resolution MS. For peptides this close in mass, a result reported only to the nearest whole Dalton is less convincing.
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.
- CJC-1295 (no DAC): 3,367.90 Da (+10.02 Da)
- Thymosin Alpha-1: 3,108.28 Da (-249.60 Da)
- CJC-1295 (with DAC): 3,647.19 Da (+289.31 Da)
Sources
- PubChem CID 16132413: Sermorelin 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.
Last updated . Written and maintained under our editorial policy. Found an error? See corrections.
Frequently asked questions
What is the molecular weight of Sermorelin?
The average molecular weight of Sermorelin (C149H246N44O42S) is 3,357.88 Da and its monoisotopic mass is 3,355.8187 Da, calculated from the molecular formula and cross-checked against PubChem CID 16132413.
What mass should a Sermorelin COA show?
The mass spectrometry result should be within about ±1 Da of 3,357.88 Da (average) or 3,355.82 Da (monoisotopic), or show a matching charge-state ion such as 1,119.61 m/z.
What HPLC purity is good for Sermorelin?
Most reputable suppliers target 98% or higher HPLC purity for Sermorelin. 99% or higher is excellent. Below 95% is a warning sign.
How can I check a Sermorelin COA for free?
Enter the COA values into the free checker on PeptideCOACheck. It compares the reported mass with the theoretical value for Sermorelin, checks purity, test date, batch number and lab name, and runs a red-flag checklist. Everything stays in your browser.
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.