What Is a Certificate of Analysis?
A Certificate of Analysis (COA) is a laboratory document that reports the results of testing performed on a specific batch of peptide. It tells you what is actually in the vial — its identity, purity, and whether it meets quality specifications. Every reputable peptide supplier provides COAs for their products, and understanding how to read one is one of the most important skills for evaluating vendor quality.
Identity: Is It the Right Compound?
The first thing a COA confirms is identity — that the substance is what the label says it is. This is typically verified by mass spectrometry (MS), which measures the molecular weight of the compound.
You want the reported molecular weight to match the known molecular weight of the peptide. For example, BPC-157 has a molecular weight of approximately 1,419.53 g/mol. If the COA reports a mass consistent with this value, the identity is confirmed.
If a COA does not include mass spectrometry data at all, that is a significant red flag — it means the identity of the compound has not been independently verified.
Purity: How Much Is the Actual Compound?
Purity is the number most people look for first, usually expressed as a percentage (e.g., 99.2%). It is typically measured by HPLC (High-Performance Liquid Chromatography).
HPLC works by passing the sample through a column that separates its components. The result is a chromatogram — a graph with peaks. The main peak represents your peptide. Any additional peaks represent impurities. The purity percentage is essentially the proportion of the total that corresponds to the main peak.
For research peptides, a purity of 98% or higher is generally considered high quality. Below 95% warrants scrutiny about the nature of the impurities.
Reading the Chromatogram
Even without deep analytical chemistry knowledge, you can learn a lot from glancing at the HPLC chromatogram:
- One dominant, sharp peak — this is a good sign. It means the sample is overwhelmingly composed of a single compound.
- A clean, flat baseline — the space around the main peak should be relatively flat. A noisy or elevated baseline can indicate multiple low-level impurities.
- Multiple notable peaks — additional peaks of significant size indicate impurities that may warrant concern, depending on their identity and proportion.
Batch Numbers: Traceability
A legitimate COA is tied to a specific batch, identified by a batch or lot number. This number should match the one printed on the vial you received. If the COA has no batch number, or if the batch number does not match your product, the COA may not correspond to your actual product — it could be a generic document reused across batches.
This is one of the simplest and most important checks you can perform: does the batch number on the COA match the batch number on your vial?
Third-Party vs. In-House Testing
COAs can come from the manufacturer's own laboratory (in-house) or from an independent third-party laboratory. Both have value, but third-party testing carries more weight because there is no conflict of interest — the testing lab has no financial stake in the results.
When evaluating a vendor, look for whether they use third-party testing and whether the COA names the testing laboratory. A COA that names a specific independent lab is more credible than one with no lab attribution.
Red Flags to Watch For
- No chromatogram image — a purity claim without the supporting graph is unverifiable. The chromatogram is the evidence; without it, you are taking the number on faith.
- No batch number — a COA without a batch number cannot be tied to your specific product.
- Mismatched batch numbers — if the COA batch number differs from your vial label, the COA may not represent your product.
- No test method listed — a legitimate COA states which analytical methods were used (HPLC, MS, etc.). Results without methodology are not scientifically meaningful.
- Suspiciously round numbers — real analytical results are precise (e.g., 99.23%). A COA that simply says "99%" with no decimal may be fabricated.
- No laboratory attribution — if the COA does not name a testing laboratory, there is no way to verify that the testing actually occurred.
Where to Find COAs
Reputable vendors publish COAs on their website, typically accessible from the product page or a dedicated certificates page. At AminoAxis, every tested batch has its Certificate of Analysis published with the full chromatogram, tied to a specific batch number that matches the vial you receive.
