Key takeaways
- Purity depends on the analytical method.
- Identity and purity are separate claims.
- High reported purity does not establish sterility, potency, or clinical suitability.
Read the method before the percentage
A percentage without a named method, chromatogram, sample link, and acceptance criteria lacks essential context. Different methods answer different questions.
Four questions, four answers
Identity asks what it is. Purity asks what else is detected. Assay or content asks how much target material is present. Sterility asks whether viable microorganisms are detected under a defined test.
Evidence, in proportion
What the evidence shows—and what it does not.
What it shows
- Chromatographic methods can estimate relative detected components under stated conditions.
What it does not show
- Every possible impurity or contaminant.
- That a sample is safe for human or animal use.
The PONY takeaway
Purity depends on the analytical method. The remaining context determines how far that fact can travel.
Frequently asked
Common questions
Is HPLC enough to prove identity?+
Not by itself in every context. Orthogonal methods such as mass spectrometry may contribute separate identity evidence.
Can a purity result prove sterility?+
No. Sterility requires a separate validated test and sampling plan.
Primary references
Sources
- FDA — Q7A GMP Guidance for APIs
Guidance on specifications, analytical procedures, and COAs.
This page is educational and does not provide medical or veterinary advice. Discussion of research does not imply approval, safety, or suitability for individual use.