What mass should a sermorelin COA show?

PubChem lists sermorelin as C149H246N44O42S with an average mass of 3357.9 g/mol and a monoisotopic mass of 3355.82 Da. A certificate should state the expected and the measured value and which kind of mass it used. A value 16 units high points to oxidised Met27, and a value several hundred units lower can mean the chain was cut at Asp3. An exact match is good evidence but, because of the D-Ala2 analogue, not the last word.

How do I know if my sermorelin is real?

Test a sample from your own vial. Mass spectrometry should find 3357.9 g/mol, HPLC gives purity and shows same-mass breakdown products such as beta-Asp3, and an amount test reports milligrams against a reference standard. Because a D-Ala2 analogue shares sermorelin's mass, a chromatographic method shown to separate the two gives the strongest answer. A label or packaging cannot tell you any of this.

Does sermorelin break down in the vial?

It can, at well known sites. Published work on GRF(1-29)NH2 found cleavage and rearrangement at aspartic acid 3 and deamidation at asparagine 8 in aqueous solution, with the peptide most stable at pH 4 to 5. Methionine 27 can also oxidise. Keep vials sealed, cool and dark until sampling, and read a low purity result together with how the vial was stored.

Can sermorelin and CJC-1293 be told apart?

Not by mass. CJC-1293 differs from sermorelin only by having D-alanine at position 2, so the formula and mass are identical. One published doping-control method found the two could not be distinguished by mass, retention time or fragment spectrum. A dedicated chromatographic method, checked against authentic standards of both, is needed to separate them.

Is sermorelin the same as CJC-1295?

No. Both derive from the first 29 residues of human growth hormone-releasing factor, but CJC-1295 carries four substitutions, at positions 2, 8, 15 and 27. A doping-control paper lists CJC-1295 at a monoisotopic mass of 3365.9 Da against 3355.8 Da for sermorelin, a gap of about 10 units that mass spectrometry resolves easily.

One of the 30 compound testing profiles

Sermorelin

Sermorelin is a 29-amino-acid peptide amide (C149H246N44O42S, average mass 3357.9 g/mol); a test should confirm that mass, look for the known breakdown products at Asp3, Asn8 and Met27, and be aware that a D-alanine analogue with the same mass exists.

Sermorelin is the 1-29 amide fragment of human growth hormone-releasing factor, hGRF(1-29)NH2, listed under the name Geref in doping-control work (Knoop et al., Analytical and Bioanalytical Chemistry, 2016).

Test your sermorelin

Identity card

Formula: C149H246N44O42S
Average mass: 3,357.9 g/mol
Monoisotopic mass: 3,355.82 Da
Length: 29 residues
Modifications: C-terminal amide (argininamide); Free N-terminal amine on Tyr1
Also sold as: GRF 1-29, hGRF(1-29)NH2, GHRH (1-29), Geref
Sequence: YADAIFTNSYRKVLGQLSARKLLQDIMSR
Note: PubChem gives an average mass of 3357.9 g/mol and a monoisotopic mass of 3355.8186992 Da, recorded as 3355.82; a doping-control paper lists the monoisotopic mass as 3355.8 Da. The single sulfur in the formula is Met27.

Source: PubChem CID 16132413, Sermorelin, Knoop A et al. Qualitative identification of growth hormone-releasing hormones in human plasma by LC-HRMS/MS. Anal Bioanal Chem. 2016;408(12):3145-53.

Check a certificate's mass against these values with the mass checker, prefilled for Sermorelin.

What usually goes wrong with sermorelin. Documented failure modes, with sources.

Aspartic acid 3: cleavage or rearrangement

Sermorelin's best documented weak point is Asp3. In aqueous solution below about pH 4, GRF(1-29)NH2 is cut at the Asp3-Ala4 bond to give GRF(4-29)NH2; above pH 4 the main route is isomerisation of Asp3 to beta-Asp3, and the peptide is most stable at pH 4 to 5 (Bongers et al., International Journal of Peptide and Protein Research, 1992). The cleavage product is three residues shorter and obvious by mass. The beta-Asp3 isomer has exactly the parent's mass, so only chromatography separates it.

Asparagine 8 deamidation

The same study found faster deamidation of Asn8 at pH 5 and above, giving beta-Asp8 and Asp8 in about a 4:1 ratio, and direct hydrolysis to Asp8 at pH 2 and below (Bongers et al., 1992). In a related GRF analogue at pH 7.4 and 37 degrees C, Asn8 deamidation was the main cause of extensive degradation (Friedman et al., 1991). Deamidation adds only +0.984 Da (Butré et al., Molecules, 2023), so on a 3.36 kDa peptide it takes accurate mass or good separation to see it.

Methionine 27 oxidation

Met27 is sermorelin's only sulfur-containing residue. Methionine is the residue most susceptible to oxidation; the sulfoxide adds 16 Da and the sulfone 32 Da (Butré et al., 2023), both clear in an intact mass spectrum. CJC-1295 has leucine at position 27 instead (Knoop et al., 2016).

A same-mass analogue: D-Ala2

CJC-1293 is GRF(1-29)NH2 with D-alanine in place of L-alanine at position 2, and in a published doping-control method it could not be told apart from sermorelin: identical mass, retention time and product ion spectrum (Thomas et al., Analytical Science Advances, 2022). An earlier paper lists both at a monoisotopic mass of 3355.8 Da (Knoop et al., 2016). A vial of the D-Ala2 analogue, or a mixture, passes a mass-only identity check.

Which tests matter most

LC-MSConfirms 3357.9 g/mol and identifies the GRF(4-29) cleavage product and the Met27 sulfoxide by mass.
HRMSResolves a deamidated Asn8 form, only +0.984 Da from the parent, from intact sermorelin.
HPLC-UVThe only routine way to see same-mass forms: beta-Asp3, beta-Asp8 and a D-Ala2 analogue.
Peptide mappingPlaces a modification at Asp3, Asn8 or Met27 and confirms the sequence differs from CJC-1295 and similar analogues.
Counter-ion contentSermorelin has many basic residues, so counter-ions can be a large share of the powder weight.

Reading sermorelin results

Sermorelin carries arginine at positions 11, 20 and 29, lysine at 12 and 21, and a free N-terminal amine. In synthetic peptides the number of trifluoroacetate counter-ions tracks the number of positive charges, and in one study trifluoroacetate reached up to 35% of total weight (Erckes et al., Pharmaceuticals, 2025). An amount result should be stated as peptide, with counter-ion content beside it. Every amount result also depends on the reference standard, so ask how the laboratory characterised its sermorelin standard.

Public Tested.ph results

No public sermorelin records yet

Each public sermorelin record will appear here with its identity, HPLC purity and measured amount against the label, once the first vial is tested.

FIG 13Amount against the label

Questions about testing sermorelin

What mass should a sermorelin COA show?: PubChem lists sermorelin as C149H246N44O42S with an average mass of 3357.9 g/mol and a monoisotopic mass of 3355.82 Da. A certificate should state the expected and the measured value and which kind of mass it used. A value 16 units high points to oxidised Met27, and a value several hundred units lower can mean the chain was cut at Asp3. An exact match is good evidence but, because of the D-Ala2 analogue, not the last word.
How do I know if my sermorelin is real?: Test a sample from your own vial. Mass spectrometry should find 3357.9 g/mol, HPLC gives purity and shows same-mass breakdown products such as beta-Asp3, and an amount test reports milligrams against a reference standard. Because a D-Ala2 analogue shares sermorelin's mass, a chromatographic method shown to separate the two gives the strongest answer. A label or packaging cannot tell you any of this.
Does sermorelin break down in the vial?: It can, at well known sites. Published work on GRF(1-29)NH2 found cleavage and rearrangement at aspartic acid 3 and deamidation at asparagine 8 in aqueous solution, with the peptide most stable at pH 4 to 5. Methionine 27 can also oxidise. Keep vials sealed, cool and dark until sampling, and read a low purity result together with how the vial was stored.
Can sermorelin and CJC-1293 be told apart?: Not by mass. CJC-1293 differs from sermorelin only by having D-alanine at position 2, so the formula and mass are identical. One published doping-control method found the two could not be distinguished by mass, retention time or fragment spectrum. A dedicated chromatographic method, checked against authentic standards of both, is needed to separate them.
Is sermorelin the same as CJC-1295?: No. Both derive from the first 29 residues of human growth hormone-releasing factor, but CJC-1295 carries four substitutions, at positions 2, 8, 15 and 27. A doping-control paper lists CJC-1295 at a monoisotopic mass of 3365.9 Da against 3355.8 Da for sermorelin, a gap of about 10 units that mass spectrometry resolves easily.

Sources

Knoop A et al. Qualitative identification of growth hormone-releasing hormones in human plasma by LC-HRMS/MS. Anal Bioanal Chem. 2016;408(12):3145-53, Analytical and Bioanalytical Chemistry (PMC)
Bongers J et al. Degradation of aspartic acid and asparagine residues in human growth hormone-releasing factor. Int J Pept Protein Res. 1992;39(4):364-74, PubMed
Friedman AR et al. Degradation of growth hormone releasing factor analogs in neutral aqueous solution is related to deamidation of asparagine residues. Int J Pept Protein Res. 1991, PubMed
Butré CI et al. Interlaboratory Evaluation of a User-Friendly Benchtop Mass Spectrometer. Molecules. 2023;28(6):2855, Molecules (PMC)
Thomas A et al. Probing for peptidic drugs (2-10 kDa) in doping control blood samples. Anal Sci Adv. 2022;3(7-8):235-243, Analytical Science Advances (PMC)
Erckes V et al. Towards a Consensus for the Analysis and Exchange of TFA as a Counterion in Synthetic Peptides. Pharmaceuticals. 2025;18(8):1163, Pharmaceuticals (PMC)
PubChem CID 16132413, Sermorelin, National Library of Medicine

Last reviewed 6 Oct 2026.