Identity, purity, and quantity are separate analytical questions. Treating them as interchangeable can lead to incorrect conclusions when reviewing a certificate of analysis for a research-use-only material.
Identity: what material was detected?
Identity testing evaluates whether the analytical characteristics of a sample are consistent with the named material. Laboratories may use mass spectrometry, chromatography, reference standards, or a combination of techniques. An identity result does not automatically establish how much material is present or whether the sample is free from every possible contaminant.
Purity: what proportion of the measured sample is the target?
Purity is commonly reported from a chromatographic method as the relative proportion of a target peak under the stated test conditions. The percentage must be read with the method, chromatogram, integration approach, and laboratory comments. A high purity percentage is not the same thing as verified vial quantity, sterility, endotoxin status, or suitability for any use outside qualified research.
Quantity or content: how much material was measured?
Quantity testing addresses the measured amount of material. The reported result may depend on the method, units, sample preparation, water content, counterions, or other stated assumptions. Researchers should compare the measured quantity with the nominal label quantity and review any uncertainty or limitations provided by the laboratory.
Additional tests answer additional questions
Sterility, endotoxin, residual solvents, microbial limits, and elemental impurities are not proven by an identity or purity test. Each requires an appropriate method and a result tied to the same sample or lot. Do not infer an unreported result from a different measurement.
How to review a report responsibly
- Match the material name and lot identifier.
- Identify every test method actually performed.
- Read the result, units, specifications, and comments together.
- Separate identity, purity, and quantity conclusions.
- Confirm that the complete report is available.
- Ask for clarification when the lot or result cannot be verified.
Transition Biotech documentation
Review available batch documents in the Transition Biotech COA Library. For the full batch-matching process, read How to Verify a Peptide COA and Batch Match. Researchers can also browse the research-use catalog and the Research Resources hub.
Research Use Only. This educational material is intended for qualified laboratory and analytical settings. It is not medical advice, dosing guidance, or a representation of suitability for human or veterinary use.
