Purity is a number. Read the trace.
We rank research peptide vendors on what they can document: an outside lab report, a batch number that matches it, and a stated method. Each ranking shows its working.
See the ranked resultsVendor results
Checked 21 September 2026 from each vendor's public pages. Claims are the vendors'. We did not test any product.
| Rank | Vendor | Documents on file | Purity on file | Method | Reviewer note |
|---|---|---|---|---|---|
| 1 | Peptryn | Outside lab: PassBatch-matched: PassMethod stated: Pass | 99.6 to 99.97% | HPLC-UV-MS | Complete public paperwork for the products we checked.Read the review |
| 2 | Core Power Peptides | Outside lab: PartialBatch-matched: PartialMethod stated: Pass | 99% (sample COA) | HPLC and MS (stated) | Claims full testing but publishes one sample.Read the review |
| 3 | Peptides for Sale | Outside lab: FailBatch-matched: FailMethod stated: Partial | Claims 99%+ | HPLC (claimed on product images) | Purity and testing claims with no documents.Read the review |
Purity on file is the figure a vendor publishes or shows on a certificate. Each review says which. Scoring: pass is 2 points, partial is 1, fail is 0, across the three document checks.
How a vendor earns a peak
The ranking is a checklist. Each criterion is something you can look up in the vendor's own documents.
- An outside lab wrote the report
- A vendor's own bench report shows what the vendor believes. An independent lab report shows what was measured.
- The report names the batch you would receive
- A lab result only counts for the vial in front of you if its batch number matches the label.
- The method is stated
- HPLC shows how much of the sample is the target compound. Mass spectrometry shows whether that compound has the right mass. We record which ones were run.
- The figure is reproducible
- Vendors that publish the raw trace, not just a percentage, let a reader check the number for themselves.
Read the documents yourself
Guides are in preparation. They explain how to check a report and stay out of dosing and health advice.
- What a peptide is, in plain languageIn preparation
- How to read a certificate of analysisIn preparation
- HPLC purity and mass spectrometry: what each one showsIn preparation
- What research-use-only labeling does and does not meanIn preparation
- Storing lyophilized peptides: the research handling basicsIn preparation