Home / Peptide COA Guide
A certificate of analysis is only useful if you know what it proves and what it leaves out. This guide walks through each test and the red flags to check before you buy.
A certificate of analysis (COA) is a lab report for one specific lot of product. It lists each test that was run, the method used, the specification the result had to meet, and the actual result. A COA describes the lot it names and nothing else, so the first check is always whether the lot number matches your vials.
| Field | Why it matters |
|---|---|
| Product and lot number | Ties the report to the vials in your hand |
| Testing laboratory | Name, address and accreditation of the lab that ran the tests |
| Test date | Shows the testing is recent and lot specific |
| Method for each test | HPLC, mass spectrometry, USP chapters; a result with no method is not verifiable |
| Specification | The pass range the result had to meet |
| Result and pass or fail | The measured value, not just a checkmark |
| Signature or approval | Who reviewed and released the report |
Identity confirms the vial contains the stated peptide, usually by HPLC retention time against a reference standard or by mass spectrometry.
Assay or potency measures how much peptide is in the vial compared with the label claim. This is the test that catches underfilled vials, and it matters more to most buyers than a purity percentage.
Purity (chromatographic purity by HPLC) reports what share of the peptide content is the target peptide rather than related impurities. A high purity number says nothing about how much peptide is in the vial.
Bacterial endotoxin testing, under USP <85>, checks for endotoxins from bacterial cell walls. Sterility testing, under USP <71> or a validated rapid method, checks for microbial growth in the finished vial.
An in-house COA is produced by the same company that made the product. A third-party COA comes from an independent laboratory. Both have a place: API manufacturers normally test their own material. For finished product, an independent lab with ISO/IEC 17025 accreditation is the stronger evidence, and you can look the accreditation up with the accrediting body, such as A2LA.
Every lot of finished product is tested by an independent US laboratory for identity and assay by HPLC, bacterial endotoxin per USP <85>, and sterility, and ships with its certificate of analysis. The API arrives with its manufacturer’s certificate of analysis, so testing covers two stages. Request a sample COA for any product when you book a call.
Certificate of analysis. It is a lab report showing the tests run on one specific lot of product and the results.
Assay. Purity tells you what share of the peptide content is the target peptide; assay tells you how much peptide is actually in the vial compared with the label. A vial can be high purity and still underfilled.
It is issued by an independent laboratory that did not make the product. Look for the lab name, address and ISO/IEC 17025 accreditation.
Yes. A COA describes one lot. If a supplier sends the same COA for different lots, it does not describe the product you received.
Book a call and our team will confirm availability and walk you through wholesale pricing.
Research brands, distributors and licensed medical practices. All information is kept strictly confidential.