How to Read a Certificate of Analysis

Reading a Certificate of Analysis does not require a laboratory background to understand the basic structure. The goal is to connect the document to the specific batch and understand what the reported tests actually tell you.

1. Start with the lot number

The lot or batch number is one of the first things to check. A useful COA should identify the batch to which its results apply.

2. Check the testing date

Testing dates provide context and help distinguish current batch documentation from older records.

3. Look at identity testing

Identity testing is intended to provide evidence about what material was analyzed. Depending on the laboratory and compound, methods can include mass spectrometry or other analytical techniques.

4. Review purity or assay results

Purity results describe the measured proportion attributed to the target compound under the stated analytical method. Read the reported value together with the method and specification rather than treating a percentage as a standalone guarantee of research suitability.

5. Look for additional QC testing

Some research COAs include additional tests, such as endotoxin screening or other quality-control panels. Interpret those results according to the stated method and acceptance criteria.

6. Identify the laboratory

Laboratory information can help establish who performed the testing and what accreditation or analytical capability is represented on the document.

A practical COA checklist

• Does the lot number match?
• Is the testing date clear?
• Is the identity method identified?
• Is the purity or assay result reported?
• Are additional QC results listed?
• Is the testing laboratory identified?

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