A certificate of analysis (COA) reports the results of defined tests performed on a particular sample or batch. It is useful technical documentation, but it should be interpreted in the context of the method, sampling plan and reporting limits. A COA alone does not prove regulatory approval, sterility, suitability for human use, or that every unit in a shipment was tested.
1. Verify sample and lot identification
Look for a batch or lot identifier, sample description, laboratory or reporting organization, report date, and a link between the tested sample and the material of interest. If that link cannot be confirmed, do not assume the report covers a different vial or lot.
2. Identify what was measured
Different tests answer different questions. An identity test investigates whether a sample is consistent with the expected compound. A chromatographic purity result estimates the fraction represented by selected analytical peaks under specific conditions. A quantitative assay seeks to determine the amount or concentration of an analyte. Those measurements should not be treated as interchangeable.
3. Examine the method
Check which technique was used, such as HPLC or mass spectrometry, and whether the report describes sample preparation, reference standards, calibration, and method validation. A chromatographic area-percent result is not necessarily equivalent to a mass-percent result, and a mass signal does not by itself establish every structural or chemical property.
4. Review units and acceptance criteria
Compare values only when their units, measurement definitions, and methods are compatible. Understand whether a stated specification is a supplier limit, an internal analytical criterion, or a validated requirement. A result that passes one method's acceptance criteria does not establish suitability for an unrelated use.
5. Understand uncertainties and test limitations
Analytical results have measurement uncertainty, detection limits, and scope limitations. A report should be read with attention to what the method can and cannot detect, how sample variability was handled, and whether method performance supports the reported precision.
6. Verify provenance
Where possible, confirm the issuing laboratory's identity and contact information and request the underlying method details or chromatograms when interpretation requires them. Supplier-provided documentation should be identified as such rather than described as independently verified without supporting evidence.
7. Avoid conclusions beyond the data
Purity, identity, sterility, endotoxin, residual solvents, microbial quality and quantitative content are distinct questions that may require separate assays. A single purity number cannot establish all of them. Nor does a COA establish regulatory authorization, clinical efficacy, or safe administration.
Further technical references
- FDA / ICH Q2(R2): Validation of Analytical Procedures — principles used to evaluate whether analytical methods are fit for their stated purposes.
- FDA / ICH Q14: Analytical Procedure Development — approaches to designing scientifically justified analytical methods.
- NIST: Standard Reference Material Definitions — definitions related to reference materials, measurement uncertainty and traceability.
For examples of documentation currently made available by the business, see APEP Biolabs' supplier-provided Certificates of Analysis. These reports should be assessed individually and checked against the relevant lot identifiers. This educational guide does not independently validate those reports.
Verify a report yourself
Watch how to match a vial's lot number to its report and confirm that report on the testing lab's own website, using GHK-Cu as an example. The same steps work for any report on our Certificates of Analysis page.
Vial shown for its lot number; GHK-Cu ships as lyophilized powder.