A certificate of analysis is the single most useful document a research-supply company can put in front of you. It is also one of the easiest documents to misunderstand, and unfortunately, one of the easiest to abuse. This guide walks through what a COA actually tells you, field by field, and what should make you skeptical.
What a COA is, and who should issue it
A certificate of analysis is a report describing the laboratory testing performed on a specific production lot of a material. The key word is specific: a proper COA is tied to one lot, identified by a lot number, and describes that lot only.
The certificate should come from an independent third-party laboratory, not from the seller's own bench. Independence matters because the lab has no stake in the result. Reputable analytical labs publish a way to verify their certificates, typically a searchable accession number or a QR code that resolves on the lab's own site.
The fields that matter
- Lot number. The anchor of the whole document. It should match the lot printed on the vial in your hand. No lot number, no traceability.
- Identity. Confirmation that the material is what the label says it is, usually established by mass spectrometry. Purity without identity is meaningless; a vial can be 99% pure something else.
- Purity and method. A percentage is only as good as the method behind it. Look for chromatography (HPLC or UPLC) coupled with detection such as UV and mass spectrometry (LC-MS). A purity claim with no stated method is a claim, not a result.
- Net peptide content. The measured amount of peptide in the vial versus the label claim. A 10 mg label with a measured content near 10 mg tells you the fill is honest. This is a separate question from purity, and good certificates report both.
- Appearance. A simple physical description, such as white lyophilized powder, that should match what you receive.
- Dates and signature. Received and reported dates place the analysis in time. A signing chemist puts a person behind the result.
Red flags worth taking seriously
- No lot number. A certificate that cannot be tied to a batch cannot be tied to your vial.
- Recycled certificates. One old COA reused across months of inventory. If every product page shows the same certificate from a year ago, the testing program is decorative.
- Unverifiable documents. If the issuing lab has no way to confirm the certificate, treat it as marketing material.
- Purity with no method. "99.9% pure" with no chromatogram, no method, and no lab name behind it is a number someone typed.
- Numbers that never vary. Real batches vary. A catalog where every compound is exactly 99.9% should invite questions, not confidence.
Why batch-specific testing matters
Peptide synthesis is a batch process. Two lots of the same compound, made months apart, can differ in purity profile, water content, and net fill. A supplier that tests each production lot, and publishes the certificate next to the lot number, is showing you the state of the material you will actually receive, not the best batch they ever made.
This is the standard we hold ourselves to: every lot we sell is listed in our public COA ledger with its testing status, and lots awaiting certification are labeled as pending rather than dressed up. When you evaluate any supplier, ours included, ask the same question of every document: does this certificate describe the vial in front of me?
All products sold by Revoryn Labs are intended for laboratory and in-vitro research use only. They are not for human or veterinary use.
For laboratory and in-vitro research use only. Not for human or veterinary use. See our research-use disclaimer.
