Peptide reference · Synthetic tetrapeptide
Epitalon COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a Epitalon Certificate of Analysis. The theoretical average molecular weight of Epitalon is 390.35 Da and the monoisotopic mass is 390.139 Da.
Check a Epitalon COA nowEpitalon reference data
| Name | Epitalon |
|---|---|
| Also known as | Epithalon, Epithalone, AEDG peptide |
| Type | Synthetic tetrapeptide |
| Molecular formula | C14H22N4O9 |
| Average molecular weight | 390.35 g/mol (Da) |
| Monoisotopic mass | 390.1387 Da |
| Residues | 4 |
| Sequence | Ala-Glu-Asp-Gly |
| Reference source | PubChem CID 219042 (formula and mass cross-checked) |
Expected mass spectrometry ions
A Epitalon COA may list one of these m/z values instead of the neutral mass. That is still consistent with Epitalon. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+H]+ | 391.15 | 391.36 |
| [M+2H]2+ | 196.08 | 196.18 |
| [M+3H]3+ | 131.05 | 131.12 |
What else can show up on a Epitalon COA
Masses calculated from Epitalon'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) | 412.12 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) | 428.09 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 504.13 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
| M − 18 (aspartimide) | 372.13 Da | Aspartimide formation at Asp |
Deletion sequences (4): one residue missing
| Signal | Value | What it means |
|---|---|---|
| des-Ala (M − 71.04) | 319.10 Da | Deletion sequence missing one Ala |
| des-Glu (M − 129.04) | 261.10 Da | Deletion sequence missing one Glu |
| des-Asp (M − 115.03) | 275.11 Da | Deletion sequence missing one Asp |
| des-Gly (M − 57.02) | 333.12 Da | Deletion sequence missing one Gly |
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 Epitalon (4 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.
Epitalon-specific things to watch
Epitalon is a four-residue peptide (Ala-Glu-Asp-Gly), about 390.35 Da. It is acidic, so some labs analyze it in negative mode, where you would see [M−H]⁻ near 389.1 m/z rather than [M+H]⁺ near 391.1 m/z.
Its small size means vials are often filled at higher milligram amounts (10 mg or more). Net peptide content testing helps confirm you actually received that amount.
Short peptides like this are easy to make cleanly, so purity under 98% is a stronger warning sign than it would be for a 40-residue peptide.
Epitalon's sequence ends Asp-Gly, the most aspartimide-prone pair in peptide chemistry. A peak 18 Da light (near 372.1 Da) is aspartimide. Iso-aspartate has the same mass, so MS alone can't see it; HPLC may show it as a separate or partly merged peak.
Acidic peptides pick up sodium readily, so [M+Na]+ near 413.1 m/z is common and is an MS artifact. "Epithalon" and "Epitalon" are the same tetrapeptide; neither is Epithalamin, the pineal extract it was modeled on.
Regulatory note, as of November 2, 2026. On October 28, 2026, HHS issued an interim enforcement discretion policy for 503A pharmacy compounding of six peptides: BPC-157, Epitalon, KPV, MOTS-c, Semax and TB-500. It covers single-ingredient preparations made by state-licensed pharmacies and physicians under listed conditions; blends are not covered, and it does not approve these peptides as drugs. For reading a COA, the useful detail is that the policy names specific forms (here, Epitalon), so a COA that states the salt form tells you more than one that does not.
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.
- GHK-Cu: 340.38 Da (-49.97 Da)
- SS-31 (Elamipretide): 639.79 Da (+249.44 Da)
- NAD+: 663.43 Da (+273.08 Da)
Sources
- PubChem CID 219042: Epitalon 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.
- HHS will permit compounding of six peptides ahead of formal rulemaking (RAPS, Oct 29, 2026): Summary of the October 28, 2026 HHS enforcement discretion policy.
- Federal Register public inspection, FR Doc 2026-22192: The policy document itself.
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Frequently asked questions
Is Epithalon the same as Epitalon?
Yes. Same sequence (Ala-Glu-Asp-Gly), same 390.35 Da average mass.
What is the peak near 372 Da on an Epitalon COA?
Aspartimide at the Asp-Gly bond, a common degradation product.
Why does my Epitalon COA list 389 instead of 391?
The lab ran negative mode. 389.1 m/z is [M-H]-.
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.