Peptryn
Rank 1 of 4. Documentation score 6 of 6.
Complete public paperwork for the products we checked.
A direct link, not an affiliate link. This vendor does not change what we say about it.
What the documents show
Publishes a COA library of 16 certificates. Each entry lists a lot number, a purity figure and an endotoxin or identity result.
Source: peptryn.com/coa/Names its testing lab, MZ Biolabs, and links each COA to a report hosted on the lab's own site. The Retatrutide 10mg COA lists HPLC-UV-MS, 99.62% purity and a negative endotoxin result. The report link loaded when we tested it.
Source: peptryn.com/coa/retatrutide-10mg/Sells retatrutide directly, in 10mg, 30mg and 60mg sizes, $130 to $320. Among the first three vendors we reviewed it was the only one stocking retatrutide. American Peptides, added on 8 October 2026, also lists it. A second lot, 30mg at 99.32% purity with identity confirmed by mass spectrometry, is published alongside the 10mg one above.
Source: peptryn.com/product/retatrutide-peptide/Says you can scan the QR code on the vial, or search the printed batch number on its lab results page.
Source: peptryn.com/lab-results/Says each batch is tested in-house, then verified by an independent US laboratory before it ships.
Source: peptryn.com/
What we could not confirm
Two COAs list an identity result instead of an endotoxin result, so the tests are not identical across products.
The library listing shows no test dates. The one date we found sits inside the report link (24 June 2026).
We did not read the full lab reports or contact MZ Biolabs, so we have not confirmed the lab issued them.
How we scored this
The score adds three checks, each worth 0 to 2 points: whether an outside lab wrote the report (see reading a certificate of analysis), whether it names the batch you would receive (see spotting a fake COA), and whether the method is stated (see HPLC and mass spectrometry). The full rules are on our methodology page.
Details
- Lab named
- MZ Biolabs
- Method
- HPLC-UV-MS
- Purity
- The site claims 99%+ purity. The three COAs we read show 99.62%, 99.78% and 99.97%.
- Company
- Peptryn, 867 N 2nd St, El Cajon, CA 92021
- Affiliate program
- 20% commission per referred sale
- Checked
- 29 September 2026, from the vendor's public pages
These are the vendor's claims and our observations. We have not tested any product. Research peptides are sold for laboratory research only and are not for human consumption.