The Peptide Sourcing Field Guide

1. A COA is the floor, not the ceiling

A Certificate of Analysis is a lab report on identity and purity. It is the most cited trust signal and the easiest to fake. A real COA names the lab, a lot number, a test date, and a result you can tie to the exact product. A PDF with no lab name, no lot, or a date that never changes is decoration, not evidence.

• Match the lot on the COA to the lot on the vial.
• Independent labs confirm a real report number.
• A COA from the seller’s own “lab” tells you little.

2. Read the vendor, not the marketing

Roughly 42% of online peptide products test with content that does not match the label. Provenance matters more than a slick site: a consistent batch-testing history, boring logistics (cold chain, real returns, a physical address), and language that stays educational rather than promising to treat or cure.

3. Red flags that should stop you cold

• “DM for a source.”
• Reused or undated COAs.
• Cure/treatment claims (illegal here, and a tell).
• Prices far below everyone else.
• Nothing you can verify independently.

4. What the 2026 FDA moves changed

The FDA ended compounding discretion for the major GLP-1 drugs and made clear a “research use only” label is not a shield. That is why the legal ground shifted under a lot of familiar sellers, and why several of the biggest are simply gone.

5. Five questions before you trust a source

• Can I tie a third-party COA to this exact lot?
• Who is the lab, and will they confirm the report?
• What is the batch-testing history, not just one report?
• Does the seller make any treatment or cure claim?
• If something is wrong, is there a real person and policy behind it?