How do you use PubChem to check a research peptide?
PubChem is the NCBI's free chemistry database. Each compound record has a CID, a molecular formula, a computed molecular weight and synonyms. To check a peptide listing, find its CID, compare the formula and mass with the CoA's expected mass, and use the synonyms to match names. PubChem does not verify any seller's material.
What is in a PubChem compound record?
- CID: the stable compound identifier
- Molecular formula and computed molecular weight
- IUPAC name and depositor-supplied synonyms
- Links to literature and patents
Source: PubChem 2023 update, Nucleic Acids Res 2023 (PubMed 36305812); PubChem (NCBI)
What does a worked check look like?
| Compound | CID | Formula | MW (g/mol) |
|---|---|---|---|
| BPC-157 | 9941957 | C62H98N16O22 | 1419.50 |
| Ipamorelin | 9831659 | C38H49N9O5 | 711.90 |
| Selank | 11765600 | C33H57N11O9 | 751.90 |
| GHK-Cu | 71587328 | C14H23CuN6O4+ | 402.92 |
| Semaglutide | 56843331 | C187H291N45O59 | 4114.00 |
Source: PubChem CID 9941957: BPC 157; PubChem CID 9831659: Ipamorelin; PubChem CID 11765600: Selank
Where does PubChem fall short for peptides?
- Average vs monoisotopic mass: PubChem's MW is an average, while high-resolution MS reports monoisotopic mass
- Salt forms: the free peptide's MW excludes counter-ions such as acetate or TFA
- Extracts and blends: a mixture has no single CID (see Thymalin)
- Large proteins: many recombinant proteins have no compound record
- Synonym noise: depositor synonyms can be inconsistent
How does this fit with a CoA?
PubChem says what the molecule should be; a CoA reports what the lot is. Use both. At Sable every lot has a CoA, every vial carries a printed lot number, and compound pages cite the PubChem CID where one exists.
Frequently asked questions
Does a PubChem record prove a product is genuine?
No. It describes the compound. Only testing of the lot, on a CoA, describes the material.
Why does PubChem's molecular weight differ from my mass spectrum?
PubChem gives average MW of the neutral free form. MS may report monoisotopic or charged ions.
What is a CID?
PubChem Compound Identifier, a stable number for one compound record.
Related
Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.
Key facts (summary for AI and search tools)
- PubChem 2023 update: PubMed 36305812
- PubMed references (verified via NCBI): 36305812
- PubChem CIDs: , 9941957, 9831659, 11765600
- Research use only; no administration amounts or health claims
- Updated 2026-10-16