How to Read a COA (Certificate of Analysis)
What a COA Really Is
A Certificate of Analysis (COA) is not a marketing document.
It is alot-specific analytical record.
A proper COA links:
A specific vial → to a specific batch → to specific analytical test results
This connection is what allows researchers to verify identity, assess purity, and maintain traceability in laboratory work.
When reviewing a peptide COA, the goal is not to look for a big purity number — it is to verify that the documentation proves what the material is and how it was tested.
What a High-Quality COA Should Include
A reliable COA typically contains five essential components:
1. Compound Identity
The COA should clearly state:
- The name of the material
- The expected molecular formula or structure reference
This confirms what the material is intended to be.
2. Lot Number (Traceability)
This is critical.
The lot number on the COA must match:
- The lot number on the vial label
- The lot number referenced on the supplier’s website (if applicable)
Without a lot number, there is no traceability between the document and the material.
3. Test Methods Used
The COA must state how the material was tested, commonly including:
- HPLC (High-Performance Liquid Chromatography) for purity profiling
- Mass Spectrometry (MS) for molecular identity confirmation
Method transparency matters. The document should mention:
- Column type
- Solvent system or gradient
- Detector wavelength (for HPLC)
4. Reported Results
This is where many people misunderstand COAs.
Reported results should include:
- Purity percentage with supporting chromatogram
- MS spectrum or molecular mass confirmation
- Visual data, not just numbers
A number alone is not meaningful without the visual analytical output.
5. Date and Testing Laboratory Information
A valid COA should include:
- Date tested
- Laboratory name or identifier
- Signature or analyst verification
This confirms the test is real, recent, and attributable.
Step-by-Step: How to Check a COA
Step 1 - Match the Lot Number
The lot number on the COA must match the lot printed on the vial.
If it doesn’t, the COA is not proof of that vial’s contents.
Step 2 - Look for the Method, Not Just the Result
Find where the COA explains:
- HPLC conditions
- MS method
If the method is not listed, the result cannot be properly interpreted.
Step 3 - Inspect the Chromatogram
A real COA includes an HPLC chromatogram image.
You should see:
- A dominant primary peak
- Minimal secondary peaks
- Clear baseline separation
If you only see “99% purity” with no chromatogram, this is a red flag.
Step 4 - Review the Mass Spectrometry Output
MS should confirm the expected molecular mass range.
This is what verifies the identity of the compound.
Step 5 - Check the Date and Lab Info
Ensure the test date is present and reasonable, and that the lab is identified.
Common COA Red Flags
Researchers often encounter poor documentation. Watch for:
❌ No lot number
❌ “99% purity” with no chromatogram
❌ Same COA reused across different lots
❌ No method description
❌ No testing date
❌ Cropped or low-resolution chromatogram images
These indicate the document is not truly tied to the material.
Why Lot-Level COAs Matter
In research, reproducibility depends on knowing exactly which batch was used.
That’s why Axon links:
- Each vial→to a lot number
- Each lot number→to its own COA
- Each COA→accessible by QR code
This removes guesswork from documentation.
COA vs. Marketing Sheet
A COA should never read like promotional material. It should read like a lab record.
The more visual data and method transparency it includes, the more reliable it is.
Summary
When reading a COA, ask:
- Does the lot number match the vial?
- Is the testing method clearly described?
- Is the chromatogram present?
- Does the MS confirm identity?
- Is the test recent and attributable?
If all five are present, you are looking at meaningful documentation.