A botanical supplement's first quality question is whether the plant in the bottle is the plant on the label. Establishing that is harder than it sounds once the plant has been processed.
Visual identification stops at the powder
Whole or cut plant material can be identified by trained examiners using macroscopic and microscopic features such as cell structure, hairs and crystal formations.
Once material is milled to a fine powder, many of those features are destroyed, and once it is extracted into a concentrate, essentially none survive.
Adulteration therefore concentrates at the processed end of the supply chain, where the physical evidence that would expose substitution has already been removed.
Chemical fingerprinting identifies compounds, not species
Chromatographic methods separate a sample's constituents and compare the resulting pattern against a reference for the expected species.
The weakness is that a marker compound may occur in related species, and a determined adulterator can add the marker to a cheaper base material to reproduce the expected peak.
Natural variation compounds the problem, since the same species grown in different soils, seasons or regions produces genuinely different chemical profiles.
DNA methods answer a different question
Genetic barcoding compares a short DNA sequence against reference databases and can distinguish species that chemical methods confuse.
Extraction and heat degrade DNA, so a highly refined extract may contain no amplifiable genetic material even when it was made entirely from the correct plant.
A failed DNA test on an extract therefore does not demonstrate adulteration, which is why the method suits raw material verification better than finished product testing.
Reference standards are the underlying constraint
Every method depends on comparison against an authenticated reference, and the reference must itself be verified back to a correctly identified specimen.
Pharmacopoeial organizations publish monographs specifying which tests apply to which botanical and what results constitute identity, providing a common standard across laboratories.
Where no monograph exists, laboratories work from published literature and their own references, which is why results on less common botanicals can differ between testing houses.
What this means at the shelf
Certification marks from independent testing organizations indicate that identity and contaminant testing occurred, though the specific tests performed vary by program.
Botanicals carry pharmacological activity, which is why identity matters at all, and anyone taking prescribed medication or managing a liver or kidney condition should raise a botanical product with a pharmacist or physician before use.