Supplier checks

Peptide vendor comparison checklist: six checks you can verify

To compare research peptide vendors, use six checks that can be verified on any vendor’s own pages: whether the analytical report can be read before paying, whether the testing laboratory is independent of the seller, which specifications the listing states, whether the vial label carries a lot number that matches the report, the legal name and payment methods, and the return terms. Here is how Pepta Labs answers each one, including where the answer is no.

The check	How to check it on any vendor's page	Pepta Labs answer
01Can you read the analytical report before paying?	Look for a report link or request form on the product page.	Yes, by email on request; the report shows RP-HPLC purity and MS identity for the production run we sourced.
02Is the testing laboratory independent of the seller?	Look for who commissioned the test and who performed it.	Yes. Pepta Labs does not test in-house. Testing is commissioned through the purchasing group; the client field may name the group or source, and supplier-identifying fields are redacted.
03Does the listing state the CAS number, formula, molecular weight and sequence?	Check the specification block on the product page.	Formula, molecular weight and quantity on every product page; CAS number, peptide sequence, PubChem CID and UNII where a verified record exists.
04Does the vial label carry a lot number that matches the report?	Compare the label with the report.	No Vial labels do not. The report covers a sampled production run and is not matched to a number printed on the vial.
05Is the seller a named US business with card payments at checkout?	Check the legal name on the Terms page and the payment methods at checkout.	Pepta Labs LLC, United States. Payment methods are shown at checkout.
06What are the return terms?	Read the returns section of the Terms.	Unopened products in original sealed condition may be returned within 30 days after delivery after obtaining return authorization. A verified damaged, incorrect, or materially nonconforming shipment may be replaced or refunded. See Terms section 9.

Not claimedSterility, endotoxin or LAL, potency, pharmaceutical-grade, cGMP, contaminant-panel or vial fill-quantity testing. The listed quantity is a supplier-stated nominal quantity.

Catalog50 listings, each with the reported HPLC purity on its product page.

Ask for the report How to read and verify a peptide analytical report Testing and documentation Research-use policy

Last reviewed September 16, 2026.