What mass should an ipamorelin COA show?

PubChem lists ipamorelin as C38H49N9O5 with an average mass of 711.9 g/mol and a monoisotopic mass of 711.39 Da. The certificate should show the expected and measured values and say which kind of mass it compared. A measured value near 818 points to GHRP-2 and one near 873 to GHRP-6, both related peptides with different structures.

How do I know if my ipamorelin is real?

Test a sample from your batch. Mass spectrometry confirms the 711.9 mass and rules out related GHRP peptides, but a version with one residue of the wrong hand has the same mass and passes. HPLC against an authentic reference shows purity and whether the D-residues are correct. An amount test then reports milligrams of peptide. A seller's certificate for another batch confirms none of this.

Is ipamorelin acetate the same as ipamorelin?

It is the same peptide with acetate counter-ions, which add weight. Ipamorelin acetate is the form named by the US FDA. The difference matters when you compare an amount with the label: a 5 mg label might mean 5 mg of salt or 5 mg of peptide. Ask the report to state which basis it used.

Does the amide at the end of ipamorelin matter for testing?

Yes. Ipamorelin ends in lysinamide, an amide rather than a free acid. A free-acid version is a different molecule, but it differs in mass by under one unit, the same +0.984 Da shift seen when an amide side chain deamidates (Butré et al., 2023). A low-resolution mass check can miss that, so accurate mass or a chromatographic comparison with a reference is needed.

One of the 30 compound testing profiles

Ipamorelin

Ipamorelin is a 5-amino-acid peptide, Aib-His-D-2Nal-D-Phe-Lys-NH2 (C38H49N9O5, average mass 711.9 g/mol), built from three non-standard residues; a test should confirm that mass, check the two D-residues have not flipped, and make sure the vial is not a related GHRP peptide.

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue, described by its developers as a GHRP-receptor agonist (Raun et al., European Journal of Endocrinology, 1998).

Test your ipamorelin

Identity card

Formula: C38H49N9O5
Average mass: 711.9 g/mol
Monoisotopic mass: 711.39 Da
Length: 5 residues
Modifications: Aib (alpha-aminoisobutyric acid, 2-methylalanine) at position 1; 3-(2-naphthyl)-D-alanine (D-2Nal) at position 3; D-phenylalanine at position 4; C-terminal amide (lysinamide)
Also sold as: Ipa
Sequence: Aib-His-D-2Nal-D-Phe-Lys-NH2
Note: PubChem gives an average mass of 711.9 g/mol and a monoisotopic mass of 711.38566570 Da, recorded as 711.39. Its one-letter string is XHXFK, because two residues have no standard letter; the three-letter form above is PubChem's condensed notation and matches the sequence published by the developers.

Source: PubChem CID 9831659, Ipamorelin, Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61.

Compare the mass printed on a certificate with the values above. The mass checker explains charge states and which mass a lab usually reports.

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

Two D-residues that can flip

Positions 3 and 4 of ipamorelin are D-amino acids (PubChem). A building block of the wrong hand, or racemisation during synthesis, gives a diastereomer, a recognised class of peptide impurity (D'Hondt et al., 2014). A diastereomer has the same formula and mass, so a mass spectrometer reports it as a pass; only a chromatographic method that separates stereoisomers shows it. The US FDA notes that ipamorelin acetate contains unnatural amino acids that add to the complexity of peptide characterisation (FDA, bulk substances with safety risks).

Histidine at position 2

Histidine has historically been a notoriously racemisation-prone residue in Fmoc peptide synthesis, particularly with base-mediated or slow couplings (Behrendt et al., Journal of Peptide Science, 2016). That adds a third stereocentre where a same-mass impurity can arise. For ipamorelin the main analytical risk is therefore the right mass in the wrong shape, which is why a well resolved HPLC method compared against an authentic reference standard matters as much as the mass result. If the laboratory has no such standard, the report should say so.

A related GHRP sold under the ipamorelin name

Ipamorelin was identified within a series of compounds lacking the central Ala-Trp dipeptide of GHRP-1, and its developers compared it directly with GHRP-2 and GHRP-6 (Raun et al., 1998). These relatives have different masses: PubChem lists GHRP-2 (pralmorelin) at 818.0 g/mol (PubChem CID 6918245) and GHRP-6 at 873.0 g/mol (PubChem CID 4345065), against 711.9 for ipamorelin. One mass measurement tells them apart.

Acetate, trifluoroacetate and peptide content

The US FDA names the substance as ipamorelin acetate, a salt form. The N-terminal amine, histidine and lysine can each carry a counter-ion, and in synthetic peptides the number of trifluoroacetate counter-ions tracks the number of positive charges, reaching up to 35% of the weight of the peptide salts in one study (Erckes et al., Pharmaceuticals, 2025). On a 711.9 g/mol peptide, that is a real gap between weight of powder and weight of peptide.

What we check in Ipamorelin. Silent, with captions.

Which tests matter most

LC-MSConfirms 711.9 g/mol and rules out GHRP-2 (818.0) or GHRP-6 (873.0) in an ipamorelin vial.
HPLC-UVThe only test here that can show a diastereomer, the main risk for a peptide with two D-residues and a racemisation-prone histidine.
Counter-ion contentSeparates acetate or trifluoroacetate from peptide so the amount is stated as ipamorelin, not salt.
Amino acid analysisConfirms composition and peptide content, provided the method can quantify the non-standard Aib and 2-naphthylalanine residues.

Reading ipamorelin results

Labels commonly read 2, 5 or 10 mg. An amount test reports milligrams of ipamorelin against a reference standard and should say whether the figure is for the peptide or for ipamorelin acetate. The net peptide content lesson explains the difference, and the content calculator estimates how much of a label amount is the target peptide.

Public Tested.ph results

No public ipamorelin records yet

Each public ipamorelin 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 ipamorelin

What mass should an ipamorelin COA show?: PubChem lists ipamorelin as C38H49N9O5 with an average mass of 711.9 g/mol and a monoisotopic mass of 711.39 Da. The certificate should show the expected and measured values and say which kind of mass it compared. A measured value near 818 points to GHRP-2 and one near 873 to GHRP-6, both related peptides with different structures.
How do I know if my ipamorelin is real?: Test a sample from your batch. Mass spectrometry confirms the 711.9 mass and rules out related GHRP peptides, but a version with one residue of the wrong hand has the same mass and passes. HPLC against an authentic reference shows purity and whether the D-residues are correct. An amount test then reports milligrams of peptide. A seller's certificate for another batch confirms none of this.
Is ipamorelin acetate the same as ipamorelin?: It is the same peptide with acetate counter-ions, which add weight. Ipamorelin acetate is the form named by the US FDA. The difference matters when you compare an amount with the label: a 5 mg label might mean 5 mg of salt or 5 mg of peptide. Ask the report to state which basis it used.
Does the amide at the end of ipamorelin matter for testing?: Yes. Ipamorelin ends in lysinamide, an amide rather than a free acid. A free-acid version is a different molecule, but it differs in mass by under one unit, the same +0.984 Da shift seen when an amide side chain deamidates (Butré et al., 2023). A low-resolution mass check can miss that, so accurate mass or a chromatographic comparison with a reference is needed.

Sources

Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-61, PubMed
Certain bulk drug substances for use in compounding that may present significant safety risks, US Food and Drug Administration
D'Hondt M et al. Related impurities in peptide medicines. J Pharm Biomed Anal. 2014;101:2-30, PubMed
Behrendt R, White P, Offer J. Advances in Fmoc solid-phase peptide synthesis. J Pept Sci. 2016;22(1):4-27, Journal of Peptide Science (PMC)
PubChem CID 6918245, Pralmorelin (GHRP-2), National Library of Medicine
PubChem CID 4345065, GHRP-6, National Library of Medicine
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)
Butré CI et al. Interlaboratory Evaluation of a User-Friendly Benchtop Mass Spectrometer. Molecules. 2023;28(6):2855, Molecules (PMC)

Last reviewed 6 Oct 2026.