Sermorelin is a 29-residue peptide with a modification at one end that is easy to miss on a certificate and expensive to get wrong. This page covers what the vial should contain, the two or three figures worth checking before you accept it, and what we supply in the USA.
What is sermorelin?
Sermorelin is GHRH(1–29) with a C-terminal amide — the first twenty-nine residues of human growth-hormone-releasing hormone, ending in an amide rather than a free acid. It is the reference analog in its class, which is why it appears so often as a comparator in published work rather than as the subject of it. Sermorelin: GHRH(1-29) and the reference analog covers the sequence, the cleavage site that dominates its stability behaviour, and why the amide is not optional.
The C-terminal amide is the thing to verify
An amide and a free acid differ by roughly one dalton. That is a small number on a large molecule and it is entirely visible on a mass spectrum — but only if the certificate reports a measured mass to a resolution that can distinguish them, and only if you compare it against the mass calculated for the amide rather than the acid.
This is the single most common way to receive something that is not sermorelin while holding a certificate that looks fine. The free-acid form is a different compound, it is cheaper to make, and on a low-resolution spectrum it is nearly indistinguishable. Ask for the measured mass and the calculated mass side by side, and check which form the calculation was done for.
The other masses worth knowing
Three common modifications each shift the mass by a predictable amount, and each announces itself as a peak at a known offset:
- Deamidation of an asparagine or glutamine adds 0.98 Da. Sermorelin contains both residue types, so this is a real degradation route rather than a theoretical one.
- Oxidation of a methionine adds 16 Da. It is the most visible sign that a vial has been stored badly or handled in air.
- Truncation — a missing residue — removes that residue’s mass. Deletion and truncation sequences are the characteristic failure of solid-phase synthesis, and they are the impurities a purity figure is mostly counting. Deletion, truncation and oxidation impurities covers what each one looks like on a chromatogram.
Reading the purity figure
Purity on a peptide certificate is an area percentage from HPLC: the main peak divided by the total area recorded. Check the detection wavelength before you read the number. Analysis at 214 nm or 220 nm detects the peptide bond, so every peptidic impurity appears. Analysis at 280 nm detects only aromatic residues — sermorelin does contain tyrosine, so it is not invisible at that wavelength, but the impurities that lack tyrosine largely are. A 280 nm figure on any peptide flatters the result.
What a third-party peptide test actually measures goes through the whole document, and why two certificates disagree explains why the same vial can return different figures at two laboratories without either being wrong.
What the milligram figure on the label means
It refers to the mass of material in the vial, which is peptide plus counter-ion plus residual water. For a 29-residue peptide with several basic sites, the counter-ion contribution is not trivial — TFA and acetate counter-ions covers what changes between the two salt forms and why the same peptide weighs differently in each. Residual water is measured by Karl Fischer titration rather than assumed, and is commonly a few percent.
The figure that accounts for both is net peptide content, determined by amino acid analysis or nitrogen determination. It is usually absent from a certificate. A vial can honestly be 98% pure and 78% peptide at the same time; net peptide content explained sets out how those two numbers coexist.
Storage and handling
Lyophilized sermorelin is hygroscopic and the deamidation and oxidation routes above are both accelerated by moisture, air and warmth. Bring vials to room temperature before opening so that condensation does not form on cold solid, close them promptly, and keep them dark. Light, oxygen and temperature covers the mechanisms; weighing lyophilized peptides covers why a balance reading climbs while you are taking it.
Where a vial will be entered more than once, aliquoting and vial entry covers how to limit the number of times material is exposed, and choosing a reconstitution solvent covers the solvent decision.
What a certificate does not establish
Identity and purity testing says nothing about sterility, nothing about endotoxin, and nothing about suitability for use in a person or an animal. Those require separate tests that are not part of routine peptide characterisation. Endotoxin, sterility and the limits of research grade covers what research grade does and does not mean.
Buying sermorelin in the USA
We ship domestically across the United States, so orders do not cross a border. Carrier and service are selected at checkout — USPS, UPS or FedEx, regular or express — orders are dispatched within one business day, and typical transit is two to five days depending on destination.
Every report we hold is published in full on the certificates of analysis page, reproduced as the laboratory issued it rather than condensed into a percentage. Certificates are not shipped with orders; a vial is matched to its certificate by cap and crimp colour against the photographs on the report. Checks to run when a shipment arrives covers what to look at before the vial goes into storage.
Sizes we supply
- Sermorelin 5 mg — the smaller vial. Worth choosing where a protocol is still being developed and a vial will be opened repeatedly, since fewer entries means less cumulative moisture uptake.
- Sermorelin 10 mg — better cost per milligram once the working quantity is settled.
Related material in the same class, where a comparison is the point of the work: tesamorelin, CJC-1295 (no DAC) and ipamorelin. The differences between the stabilised analogs are covered in tesamorelin as a stabilised GHRH analog and CJC-1295 with and without DAC, and the modifications that change a peptide’s half-life in general are covered in peptide half-life and analog modifications.
All material is supplied for laboratory research use only. It is not a drug, not a supplement, and not for use in humans or animals.
