How to read a certificate of analysis
Premius Pharmacy
A certificate of analysis (CoA) is the document that lets you judge a batch without taking it on trust. It should accompany every lot we ship, and it is worth knowing which parts carry real information and which parts are boilerplate.
Identity
The CoA states what the material is meant to be and how that was confirmed. For a peptide, expect a mass consistent with the expected molecular formula, usually from mass spectrometry. If the reported mass does not match the sequence you expected, nothing else on the page matters.
Purity
Purity is reported as a percentage, normally from HPLC (high-performance liquid chromatography). Look at the method, not only the number: a purity figure means little without the column, gradient and detection wavelength that produced it. A figure quoted to two decimals from a method nobody can inspect is marketing, not analysis.
The chromatogram
The trace should show a single dominant peak with the impurities resolved around it. Use it to confirm that the purity percentage describes what you can actually see in the method. If the trace is missing, a shoulder is ignored, or the baseline is not flat, the percentage is worth less than it appears.
Method and instrumentation
- The analytical method named (for example, reverse-phase HPLC)
- The detector and wavelength used
- The reference standard the run was calibrated against
- The date of analysis and the batch identifier
Matching the certificate to your vial
The batch number on the certificate must match the batch number on the vial you received. A certificate proves what one lot contained; it says nothing about a vial from a different lot. This is why we publish a certificate per batch rather than one generic document.
What a certificate is not
A certificate of analysis is a laboratory document. It describes identity and purity for a specific batch; it is not a statement about any use outside the laboratory. Our compounds are supplied for laboratory research use only.
Every certificate we publish is listed on the lab test results page, and the batch you receive can be matched to its certificate by lot number. To go a level deeper into the purity figure itself, read HPLC purity explained.