How to read a certificate of analysis

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A certificate of analysis (COA) is a laboratory's written report on a specific sample. It is the single most useful document a research supplier can publish, and also the one most often misread. This guide walks through the parts of a typical certificate and what to check.

What a certificate is, and is not

A COA reports what a laboratory observed when it analyzed one sample using stated methods. It is evidence about that sample. It is not a general statement about a product name, and it is not a warranty about other material that happens to share the name.

Three consequences follow:

1. A certificate tells you about the sample that was tested, not about every vial sold under the same name.
2. A certificate for a different product or strength than the one on your vial tells you about a different material.
3. A summary figure lifted from a certificate onto a product page has lost the context that makes it meaningful.

The parts of a certificate

Header and identification

The header identifies the laboratory, the client who submitted the sample, and the sample itself. Look for:

• Laboratory name and contact details. An independent, third-party laboratory should be identifiable and contactable.
• Report or certificate number. Unique to this document.
• Sample description. The product and strength should match the label on your vial.
• Dates. When the sample was received and when the report was issued.

Methods

Each result should name the analytical method used to obtain it. Common methods on peptide certificates include high-performance liquid chromatography (HPLC) for purity and mass spectrometry (MS) for identity. The method section tells you how a number was produced, which is what makes the number interpretable.

Results and acceptance criteria

Results are usually presented in a table with, for each test, the specification or acceptance criterion and the observed value. Read them together: a result only means something relative to the criterion it was measured against.

Signatures and authorization

A certificate is normally signed or electronically authorized by the analyst and a reviewer. This is the laboratory taking responsibility for the content.

Checking a certificate against a vial

When a certificate is published on this site, it is linked from the compound it describes. To check it:

1. Confirm the product and strength on the certificate match your vial label.
2. Confirm the issuing laboratory and the report date.
3. Read the method used for each result before reading the result itself.

If any of these do not line up, treat the certificate as not applying to your vial and ask.

Terminology

Term	Meaning
Sample	The portion of material actually submitted to the laboratory.
Purity	The proportion of the sample that is the stated material, as measured by the stated method.
Identity	Confirmation that the material is what it is labeled as, typically by mass.
Acceptance criterion	The range or limit a result is compared against.

Further reading

The Quality & Testing page describes how Red Fern moves material from receipt to release and when certificates are published.