Two ways to measure content
A standardization percentage is only meaningful with its method. The two most common assays for botanical extracts are HPLC and UV — and they don't always measure the same thing.
HPLC — a specific marker
High-Performance Liquid Chromatography separates and quantifies a specific marker compound (e.g. osthole, gingerol, luteolin). It answers: "how much of this exact molecule is in the extract?" Use it when your specification targets a single defined compound.
UV — a compound class
UV-Vis spectrophotometry measures a class of compounds that absorb at a wavelength (e.g. "total flavonoids" calculated against a reference). It answers: "how much of this family is present?" UV figures are typically higher than HPLC figures for the same material because they sum a group, not one molecule.
Why the number differs
A material can read "≥30% total polyphenols (UV)" and "1.5% A-type PACs (HPLC)" at the same time — both are correct, but they measure different things. Comparing a UV percentage from one supplier with an HPLC percentage from another is not an apples-to-apples comparison.
What to confirm
- Which compound or class is measured.
- Which method (HPLC or UV) produced the figure.
- That your supplier and any competing quote use the same method before you compare.
To confirm the assay method behind a specification, request the specification sheet or COA.