How to spot a fake peptide COA: nine checks for altered or borrowed lab reports

Analytical surveys of peptide products bought online show how far documents and contents can drift apart. Belgium's national public laboratory for medicines and consumer safety (then WIV-ISP, now Sciensano) screened the ten falsified peptide products it encountered most often, bought from three suspected illegal internet pharmacies, and reported high variation in content per unit, purities between 5% and 75% for cysteine-containing peptides, and arsenic and lead contamination (Janvier et al., Talanta 2018).

A 2024 test-purchase study of semaglutide vials bought from online sellers outside the licensed supply chain measured purities of 7.7% to 14.37%, against the 99% printed on the labels, and detected endotoxin in every vial (Ashraf et al., J Med Internet Res 2024). A Polish medicines laboratory identified an unlisted glycine analogue of GHRP-2 (a heptapeptide of 874.02 Da) in a seized vial by high-resolution LC-MS/MS (Popławska and Błażewicz, Drug Test Anal 2019), a reminder that the molecule inside can differ from the one on the label.

None of these products came with an honest certificate. The lesson for any lab is that a COA is a claim to verify, not a result to accept.

Work through these in order. The first one settles most cases, and each later check catches a different kind of problem.

1. Confirm with the issuing lab: open the lab's own website (not a link inside the PDF), enter the report ID or scan the QR code, or email the lab. Some lab portals search by the client the report was issued to, so ask the seller which name to search under.
2. Match the lot: the lot or batch number on the report must match the vial. A single report reused across lots documents one sample, not yours.
3. Read the client field: a report issued to a different brand may be genuine for that brand's sample and still say nothing about this seller's material.
4. Look for the chromatogram: a purity percentage should come with a trace and a peak table. Integrated areas should add up to about 100%, and the main peak's retention time should be plausible for the method listed.
5. Compare chromatograms across reports: an identical baseline, noise pattern and peak shape on reports for different compounds or lots means the image was reused.
6. Check identity by mass: the observed mass, or the [M+zH]z+ ions, should match the theoretical mass for the sequence. Use the expected m/z calculator to see which ions to expect.
7. Find the measured quantity: a measured mg per vial is a result; a label claim repeated on the report is not.
8. Check the lab's accreditation scope: an ISO/IEC 17025 certificate is issued by an accreditation body (A2LA, ANAB and others signed up to the ILAC arrangement) and lists the specific methods covered. Look the lab up on the body's directory and confirm the method on the report is in scope.
9. Inspect the document itself: mixed fonts, numbers that sit off the table grid, or text that can be selected on top of an image are signs of editing. Compare against another report from the same lab.

Patterns across a catalog matter as much as any single PDF. Be cautious when a seller shows the same report for every lot, will not say which lab tested the material, publishes purity figures with no method, hides the client field on every report, or cannot produce a report for the lot actually shipped.

A seller that publishes lot-level reports with lab report IDs, says which ones the lab has confirmed and which are pending, and answers questions about methods is giving you something you can check.

Every published lot report is listed in the open COA dataset with its lab, accession number, test date, methods, purity and measured quantity, as a table and as CSV and JSON files. Where the issuing lab hosts a public lookup, the product page links to it; where the lab has not yet confirmed a report publicly, the page says lab confirmation is pending rather than implying it. You can look up any lot by the number printed on the vial.

Apply the same nine checks to our reports as to anyone else's.