A Certificate of Analysis (COA) accompanies a released batch of reference material and records the analytical results obtained at the time of release. For laboratory teams, the COA is the primary document linking a physical vial to a defined set of measurements.
Batch reference
The batch number is the identifier that ties a vial to its production record. Every vial in a shipment should carry a label matching the batch number on the certificate. If the numbers do not match, stop and query the shipment before use, because the analytical data may belong to a different production lot.
Test date
The test date tells you when the measurements were taken. It is not an expiry date. Analytical results describe the material at the point of release; they say nothing about how the material behaves after prolonged storage or after reconstitution.
Method
The method field states how purity was determined, most commonly reverse-phase HPLC with UV detection. The method matters because purity values obtained under different chromatographic conditions are not directly comparable. When comparing two batches, confirm that the method is the same before drawing conclusions.
Measured purity
Purity is normally reported as the area percentage of the target peak relative to total peak area. It describes the composition of the sample under the stated method. It is not a statement about biological activity, and it does not describe suitability for any application outside laboratory research.
Testing laboratory
Naming the laboratory that performed the analysis allows the result to be traced. Where testing is carried out by an independent facility, the certificate should identify that facility rather than only the supplier.
What a COA does not cover
- Stability over time or after reconstitution
- Microbial or endotoxin content unless explicitly listed
- Suitability for any specific assay or application
- Anything relating to human or animal use
Filing practice
Keep the certificate with the batch record and note the date the vial was first opened. When a study refers back to a specific batch, the certificate is the document that supports the traceability chain.