How to Read a Peptide Certificate of Analysis (COA)

A Certificate of Analysis (COA) is the document that connects a vial in your lab to actual analytical data. It should tell you what the compound is, how pure it is, who tested it, and which batch the results belong to. This guide walks through each part of a typical peptide COA and explains what to look for.

1. Header information: who, what, and when

• Compound name and sequence. The COA should name the peptide and ideally list its amino acid sequence or molecular formula.
• Batch or lot number. This must match the lot number printed on your vial label. A COA without a batch number cannot be tied to the product you received.
• Testing laboratory. A credible COA names the lab that ran the analysis. An unnamed "third-party lab" is much harder to verify.
• Test date. Results should be recent relative to the batch's manufacture.

2. Purity by HPLC

High-performance liquid chromatography (HPLC) separates the components of a sample so each can be measured. Purity is usually reported as the percentage of the total peak area that belongs to the target peptide, for example "Purity: 99.1%". A chromatogram, the graph of peaks, is often attached. A single dominant peak with small minor peaks indicates a clean sample.

Keep in mind that HPLC purity describes how much of the detected material is the target peptide. It does not, on its own, prove the peptide's identity.

3. Identity by mass spectrometry

Mass spectrometry (MS) confirms identity by measuring the molecular mass of the compound. A good COA lists both the theoretical mass, calculated from the sequence, and the observed mass. These values should agree closely. HPLC purity plus MS identity together give a far stronger picture than either test alone.

4. Peptide content and quantity

Purity and quantity are different measurements. A lyophilized peptide powder can also contain water and counter-ions such as acetate or trifluoroacetate (TFA) left over from synthesis. Some COAs report net peptide content or a measured quantity per vial, which tells you how much of the vial's stated amount is the peptide itself.

5. Additional tests

• Endotoxin (LAL test). Measures bacterial endotoxin, which matters for many cell-based research models.
• Sterility. Confirms the absence of microbial growth.
• Appearance and solubility. Basic physical checks, for example "white lyophilized powder".

Red flags

• No batch number, or a batch number that does not match the vial.
• No named laboratory, or a lab that cannot be located.
• Purity reported with no method stated.
• Identical COAs reused across different products or batches.
• No way to independently verify the document.

How Azyrion Labs handles COAs

Every Azyrion Labs compound ships with a batch-specific COA, and each batch can be looked up through our COA Verification portal. Enter the lot number from your vial to view the matching certificate. Learn more about our process on the Quality Standards page.