Peptide reference · 16-residue modified hGH fragment with a disulfide bond
AOD-9604 COA check: molecular weight, formula and what to look for
Use these reference values to check the identity result on a AOD-9604 Certificate of Analysis. The theoretical average molecular weight of AOD-9604 is 1,815.08 Da and the monoisotopic mass is 1,813.860 Da.
Check a AOD-9604 COA nowAOD-9604 reference data
| Name | AOD-9604 |
|---|---|
| Also known as | Tyr-hGH Fragment 177-191, AOD9604 |
| Type | 16-residue modified hGH fragment with a disulfide bond |
| Molecular formula | C78H123N23O23S2 |
| Average molecular weight | 1,815.08 g/mol (Da) |
| Monoisotopic mass | 1,813.8604 Da |
| Residues | 16 |
| Reference source | PubChem CID 71300630 (formula and mass cross-checked) |
Expected mass spectrometry ions
A AOD-9604 COA may list one of these m/z values instead of the neutral mass. That is still consistent with AOD-9604. How charge states work.
| Ion | m/z (monoisotopic) | m/z (average) |
|---|---|---|
| [M+H]+ | 1,814.87 | 1,816.09 |
| [M+2H]2+ | 907.94 | 908.55 |
| [M+3H]3+ | 605.63 | 606.03 |
| [M+4H]4+ | 454.47 | 454.78 |
What else can show up on a AOD-9604 COA
Masses calculated from AOD-9604's formula 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) | 1,835.84 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) | 1,851.82 Da | Potassium adduct: an MS artifact. The [M+K]+ ion itself is at M + 38.96 |
| TFA adduct (M + 113.99) | 1,927.85 Da | Trifluoroacetic acid from purification seen as an adduct; residual TFA salt is real vial content |
| M + 0.98 (deamidation) | 1,814.84 Da | Asn/Gln deamidation; overlaps the natural isotope peak, needs high-resolution MS |
| M + 2 (reduced) | 1,815.88 Da | Disulfide not formed / reduced form |
Deletion sequences (9): one residue missing
| Signal | Value | What it means |
|---|---|---|
| des-Tyr (M − 163.06) | 1,650.80 Da | Deletion sequence missing one Tyr |
| des-Leu/Ile (M − 113.08) | 1,700.78 Da | Deletion sequence missing one Leu/Ile |
| des-Arg (M − 156.10) | 1,657.76 Da | Deletion sequence missing one Arg |
| des-Val (M − 99.07) | 1,714.79 Da | Deletion sequence missing one Val |
| des-Gln (M − 128.06) | 1,685.80 Da | Deletion sequence missing one Gln |
| des-Ser (M − 87.03) | 1,726.83 Da | Deletion sequence missing one Ser |
| des-Glu (M − 129.04) | 1,684.82 Da | Deletion sequence missing one Glu |
| des-Gly (M − 57.02) | 1,756.84 Da | Deletion sequence missing one Gly |
| des-Phe (M − 147.07) | 1,666.79 Da | Deletion sequence missing one Phe |
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.
For AOD-9604, 98% or higher HPLC purity is the usual research-grade benchmark. The full checklist is in how to read a peptide COA.
AOD-9604-specific things to watch
AOD-9604 is the 177-191 fragment of human growth hormone with an added N-terminal tyrosine, cyclized by a disulfide bond between its two cysteines. Reference mass is about 1815.1 Da.
If the disulfide is not formed (the reduced, open form), the mass is about 2 Da higher. A result around 1817 Da can indicate incomplete oxidation; check whether that figure was measured or is just the theoretical value a vendor quotes for the open form.
Native hGH 176-191 has phenylalanine where AOD-9604 has its added tyrosine, so the natural fragment is about 16 Da lighter (near 1,799.1 Da with the disulfide formed). The 15-residue hGH 177-191 on its own is about 163 Da lighter (near 1,651.9 Da). Vendors sometimes sell the tyrosine version as "HGH Fragment 176-191", so go by the mass on the COA, not the product name.
AOD-9604's two cysteines are meant to form one internal disulfide bond. If they bond between two molecules instead of within one, you get a dimer of about 3,630.2 Da (average), an impurity. That dimer's 2+ and 4+ ions land on the same m/z values as the normal molecule's 1+ and 2+ ions, so an m/z list alone can't reveal it. Odd charge states (a 3+ ion near 1,210.3 m/z), half-unit isotope spacing or the HPLC trace can.
Its charge states sit near 907.9 (2+) and 605.6 (3+) m/z. Products labeled "HGH Fragment 176-191" are sometimes the same tyrosine-containing molecule, listed near 1,817.1 Da in its open form. A COA near 1,799 to 1,801 Da points instead to the native phenylalanine fragment.
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.
- MOTS-c: 2,174.59 Da (+359.51 Da)
- BPC-157: 1,419.54 Da (-395.54 Da)
- Kisspeptin-10: 1,302.44 Da (-512.64 Da)
Sources
- PubChem CID 71300630: AOD-9604 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 does 907.9 m/z mean on an AOD-9604 COA?
The [M+2H]2+ ion of the 1,813.9 Da (monoisotopic) molecule.
How do I tell AOD-9604 from HGH Fragment 176-191?
By mass. AOD-9604 carries a tyrosine at its N-terminus and is about 1,815.1 Da with its disulfide formed, or 1,817.1 Da open. Native hGH 176-191 has phenylalanine there and is about 16 Da lighter (near 1,799.1 Da, or 1,801.1 Da open). Some products sold as "Fragment 176-191" are actually the tyrosine version.
What does an AOD-9604 peak near 3,630 Da mean?
Two molecules joined by disulfide bonds between them rather than within each one (a dimer). It's an impurity, and it can hide behind the normal molecule's m/z values.
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.