A sample can produce a clean analytical trace without being the intended chemical. Conversely, the intended chemical can be present in a mixture containing substantial impurities. Identity and purity therefore belong in separate fields in a research-material review.

FDA's specifications guidance distinguishes tests and acceptance criteria used to characterize drug substances and products. Its broader lesson for readers is that one attractive number cannot stand in for a complete description of quality. FDA Q6A specifications and acceptance criteria

Ask what each measurement can resolve

An identity method should distinguish the intended material from plausible alternatives. A purity method evaluates components visible under that method's conditions. The instrument, separation and detector influence what is observed. A reported percentage is meaningful only with the method and the calculation that produced it.

Different methods can provide complementary evidence. That does not mean more tests are always better. The useful question is whether the test set addresses the likely ways the material could be incorrect for the experiment. A specialist may need to consider sequence-related variants, chemical modifications or other confounding components.

Avoid turning analytical quality into clinical safety

Even strong identity and purity evidence does not establish biological activity, sterility, absence of endotoxin or suitability for administration to people. Those are distinct claims. A research experiment may also be sensitive to an impurity that would be invisible in a general purity headline.

An AXON review should state the measured property, method and uncertainty in plain language. “The report supports the assigned identity using the listed method” is more informative than a broad quality label. If the method cannot resolve a relevant alternative, identify that gap and seek analytical review. No claim about a named supplier or a human-use product follows from this general framework.