RPB
Guide 04

Reading a Certificate of Analysis

A Certificate of Analysis (CoA) is a lab report on one batch. Read well, it tells you a lot. Read uncritically, it tells you what someone wanted you to believe.

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Draft content — pending editorial and medical review.
Before you start
  • The and the vial it belongs to
  • The lot (batch) number from the vial label
  • The compound’s profile, for its expected molecular weight
When you upload a CoA to your vial log, we remove company names and logos before storing it.

Line by line

  1. Lot number

    Should match the number on your vial exactly. A for a different lot tells you nothing about yours.

  2. Test date

    A recent date matters. A report years older than the vial is a warning sign.

  3. Identity (mass spectrometry)

    Confirms the molecule has the expected molecular weight. Compare it to the value on the profile.

  4. Purity (HPLC)

    The share of the sample that is the target peptide, often reported as a percentage. It does not say what the rest is.

  5. Endotoxin

    Bacterial fragments that can cause fever and inflammation, reported in EU/mg. Many reports leave it out; that absence is information.

    A purity figure says nothing about . They are separate tests.

  6. Testing lab

    An independent lab is more meaningful than an in-house one. A report with no lab named can’t be checked.

What a CoA can’t tell you

It can’t tell you how the vial was stored after testing, whether the report is genuine, or whether the amount in your vial matches the label. It describes one sample of one batch on one day.

Common mistakes

Trusting a high purity number alone. 99% pure still leaves impurities unnamed.
Not matching the lot. A generic is not evidence about your vial.
Ignoring missing tests. No result means endotoxin wasn’t tested, not that it is absent.