---
title: "How do you use PubChem to check a research peptide? | Sable Peptides"
description: "How a buyer or lab can use a PubChem compound record (CID, formula, molecular weight, synonyms) to check a research peptide listing, where PubChem falls short for peptides, and worked examples from the catalogue."
canonical: https://www.sablepeptides.co.uk/guides/pubchem-records-for-research-peptides-how-to-use-them
dateModified: 2026-10-16
publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

# 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)](https://pubmed.ncbi.nlm.nih.gov/36305812/); [PubChem (NCBI)](https://pubchem.ncbi.nlm.nih.gov/)

## 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](https://pubchem.ncbi.nlm.nih.gov/compound/9941957); [PubChem CID 9831659: Ipamorelin](https://pubchem.ncbi.nlm.nih.gov/compound/9831659); [PubChem CID 11765600: Selank](https://pubchem.ncbi.nlm.nih.gov/compound/11765600)

## 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

-   [Molecular weights compared](/guides/research-peptide-molecular-weights-compared)
-   [Names and synonyms](/guides/research-peptide-names-codes-and-synonyms)
-   [Thymalin vs Vesugen](/guides/thymalin-and-vesugen-extract-vs-defined-peptide)
-   [Reference library](/ref)

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