A certificate of analysis is a batch-specific summary of test results. It is useful only when the document can be connected to the material in hand and when the analytical method is suitable for the question being asked.
Research use only: This guide concerns laboratory material evaluation. It is not medical advice and does not establish suitability for human or veterinary use.
1. Match the document to the vial
Start with the peptide name, batch or lot number, test date, and quantity or presentation. The lot shown on the COA should match the lot on the product label. A generic document without a batch identifier provides much less traceability.
2. Separate identity from purity
Identity and purity answer different questions. Mass spectrometry may support molecular identity by comparing the observed mass with the expected value. HPLC commonly reports the relative area of the main chromatographic peak. A high HPLC area percentage does not, by itself, prove identity or disclose every possible non-peptide component.
3. Look for method and instrument details
A useful report states the test method, instrument or detector, sample date, and result. For chromatographic testing, look for a chromatogram, retention information, peak table, and clear units. For mass spectrometry, look for the expected and observed mass and the spectrum. The method should be appropriate for its intended analytical purpose.
4. Check who performed the test
Identify the laboratory, report number, analyst or authorization status, and contact information where available. Independent third-party testing can add separation between manufacture and analysis, but the report still needs traceability and a suitable method.
5. Read qualifications and limits
Terms such as “conforms” or “passes” should be tied to a stated specification. Note whether the result is reported as an area percentage, mass fraction, concentration, or another measurement. A COA should not be treated as a complete toxicology, sterility, endotoxin, or clinical-suitability assessment unless those tests are explicitly listed and supported.
A practical COA checklist
- Product and lot match the label
- Testing date and report identifier are present
- Identity and purity are reported separately
- Chromatogram or spectrum is attached where relevant
- Method, units, specification, and result are clear
- Laboratory and authorization details are traceable
Reference
The ICH Q2(R2) guideline explains that an analytical procedure should be demonstrated to be suitable for its intended purpose and discusses characteristics including specificity, accuracy, precision, and range. See the official ICH Q2(R2) guideline.