A Certificate of Analysis tells you what’s actually in the vial.
It’s the only document that connects the marketing copy on a product page to the chemistry inside the bottle you receive. If you can’t read it, you can’t verify what you bought. If you don’t verify what you bought, your results aren’t reproducible.
This is a field guide. Every field that should be on a peptide COA, what it means, and what to do when something is missing or wrong.
Why the COA exists
Peptide synthesis is a controlled chemical process, but it’s not deterministic. Each batch is slightly different. Purity varies. Impurities vary. Salt content varies. Net peptide content varies.
The COA is the manufacturer’s and the testing laboratory’s record of what that specific batch actually came out to be. It is not a marketing document. It’s a measurement record. The right way to read it is the way you’d read a lab notebook: trust the data, verify the source.
What should be on every peptide COA
The fields below are the minimum for a defensible certificate.
1. Compound name and structure
The full name of the peptide. Not an abbreviation only. Many peptides have similar abbreviations that refer to entirely different compounds. The certificate should also reference the molecular formula and molecular weight.
2. Lot or batch number
A unique identifier for the synthesis batch. This number should be printed on the vial label. If the lot number on the vial doesn’t match the lot number on the certificate, the certificate is for a different batch. That’s the most common failure mode in low-quality suppliers.
3. Test date
When the analysis was performed. A COA from 2019 attached to a vial sold in 2026 is a red flag. Either the inventory has been sitting for years (stability question) or the certificate has been recycled (integrity question).
4. Analytical methods used
The actual instruments and protocols used to generate the results. For peptides, the standard suite is:
- HPLC with UV detection. Measures purity by separating the compound from impurities. Reports a chromatogram and a percent purity.
- Mass spectrometry (MS). Confirms identity by measuring the molecular weight. Reports the observed mass against the theoretical mass.
- Optional: Endotoxin testing (USP <85> LAL assay) for batches intended for sensitive applications.
- Optional: Net content / water content via Karl Fischer or similar.
5. Purity result
Usually reported as a percentage, with the analytical method specified. “99.1% by HPLC” is meaningful. “99%+” without a method is not.
6. Identity confirmation
The observed mass from mass spectrometry, compared to the theoretical mass for the named compound. They should match within a small error margin. If the masses don’t match, the compound on the certificate is not the compound you ordered.
7. Testing laboratory name and signature
The name of the laboratory that performed the analysis. Not just “in-house QC.” A named, addressable, third-party analytical laboratory whose reputation depends on accurate testing.
8. Verifiable certificate ID
A code, serial number, or search ID that lets you look up the certificate on the testing laboratory’s own website or database. This is the difference between a certificate you have to trust and a certificate you can verify.
How to verify a COA in three minutes
- Check the lot number. Read the lot number off the vial. Confirm it matches the lot number printed on the certificate.
- Check the testing laboratory. The lab named on the certificate should be a real, addressable, independent analytical laboratory. Search them. Confirm they exist.
- Verify on the lab’s own database. Take the certificate ID from the COA and search it on the testing laboratory’s website. If the certificate appears in the lab’s own records, it’s real. If it doesn’t, the certificate was generated somewhere else.
That third step is the one most researchers skip and most fake certificates fail. The supplier can produce a beautiful PDF. The testing laboratory cannot.
ANKR Lab certificates are issued by Freedom Diagnostics and searchable at FreedomDiagnosticsTesting.com using the search code on the certificate. See an example by browsing any product page in the catalog.
COA red flags
- No analytical method specified. “99% pure” without HPLC means nothing.
- No mass spectrometry data. Purity without identity is purity of an unknown compound.
- No testing laboratory name. Just a logo, just “QC,” or “in-house testing.”
- No lot number, or a generic batch like “BATCH-001.”
- Same certificate attached to multiple unrelated products.
- Test date older than the manufacturing date on the vial. The certificate predates the product.
- Certificate verifiable only through the supplier, not the lab.
What a clean COA looks like
A clean peptide COA fits on one or two pages. It has the testing laboratory’s letterhead, a clear compound name, the lot number, the test date, every analytical method used, the chromatogram from HPLC, the mass spec output, the percent purity, the identity confirmation, the certificate ID, and a signature or seal.
The reader should be able to look at it and know exactly what was measured, how, when, and by whom. No marketing language. No hand-waving. No “trust us.”
Frequently asked
What is HPLC and why is it on a peptide COA?
HPLC stands for High Performance Liquid Chromatography. It’s an analytical method that separates the components of a mixture so they can be measured individually. For peptides, HPLC with UV detection is the standard method for measuring purity. The chromatogram on the COA shows the separated peaks, and the percent purity is calculated from the area of the main peak relative to the total.
What is mass spectrometry on a peptide COA?
Mass spectrometry measures the mass of a molecule. For a peptide, it confirms identity by comparing the observed mass to the theoretical mass calculated from the peptide’s sequence. A peptide that’s 99% pure but has the wrong mass is 99% pure of the wrong compound.
What is endotoxin testing on a peptide COA?
Endotoxin testing measures bacterial endotoxin contamination using the LAL (Limulus Amebocyte Lysate) assay, typically reported in endotoxin units per milligram or per milliliter. USP <85> is the pharmaceutical standard. ANKR’s flagship batches are tested to a pharmaceutical-grade endotoxin standard.
How do I verify that a peptide COA is authentic?
Authentic peptide COAs are issued by named analytical laboratories and verifiable through the laboratory’s own records. The most reliable verification is to take the certificate ID and search it on the testing laboratory’s database, not the supplier’s website. If the certificate exists in the lab’s own system, it’s real.
Should every batch of peptide have its own COA?
Yes. Each batch is a separate synthesis with its own purity profile, and each batch should have a Certificate of Analysis specific to that lot. Reusing a single COA across multiple batches is a serious quality control failure.
See it in practice
If you want to see what a properly published COA looks like in production, every product on the ANKR catalog has its certificate linked from the product page. The full description of how our testing works is at /testing/.