How to Read a Peptide Certificate of Analysis (COA)

What a COA is

A Certificate of Analysis is a lab report tied to one specific production batch. It documents what was tested, how, by whom and with what result. A COA only means something if its batch number matches the number printed on your vial.

The key fields

Most peptide COAs share the same core fields:

• Batch / lot number — must match your vial label exactly.
• Product name and amount per vial — for example, 10 mg.
• HPLC purity — the share of the sample that is the target peptide, shown as a percentage. Research-grade material is commonly reported at 98% or higher.
• Mass spectrometry (MS) — confirms identity by checking the measured molecular mass against the peptide's expected mass.
• Test date and testing laboratory — who ran the analysis and when.

HPLC purity vs. identity

HPLC tells you how pure a sample is, but not on its own what it is. Mass spectrometry confirms identity. A trustworthy COA reports both: a high purity number for the wrong molecule is still the wrong molecule.

Red flags

Be cautious when you see any of the following:

• No batch number, or one that doesn't match your vial.
• The same COA reused for many different batches.
• No testing lab named, or no test date.
• Purity reported without a chromatogram or method details.
• A supplier that only shares COAs by private request.

How DenaLab handles COAs

Every DenaLab lot has its batch results published on our Verify page. Enter the batch number from your vial to see the matching purity, test date and lab, and view the full report.