Two suppliers can both quote “curcumin 95%” and be describing chemically different material — because the number depends entirely on what is measured and how. The two variables are total curcuminoids vs pure curcumin and HPLC vs UV. Getting both right on the purchase order is the difference between a defensible label and a costly mismatch at incoming-goods.
Total Curcuminoids vs Pure Curcumin
The first ambiguity is what the 95% counts. Turmeric’s actives are three curcuminoids — curcumin, demethoxycurcumin and bisdemethoxycurcumin. “95%” almost always refers to total curcuminoids (all three), but it is occasionally read as 95% pure curcumin, which is a far more processed, more expensive and chemically narrower material.
Write it explicitly: “NLT 95% total curcuminoids by HPLC.” If you actually need a high-purity single-compound material, say “95% curcumin” and expect a different price and profile.
Why HPLC and UV Disagree
The second ambiguity is the method. The same powder reports a different number depending on the assay:
- HPLC (High-Performance Liquid Chromatography) — physically separates the three curcuminoids and quantifies each against reference standards. It is specific, gives a per-compound breakdown, and produces a chromatogram you can inspect.
- UV-Vis spectrophotometry — measures total absorbance of the coloured fraction at a curcumin wavelength. It is fast and cheap but non-specific: it captures anything that absorbs in that range, so it reads higher than HPLC on the same material.
A “95% by UV” can correspond to a meaningfully lower HPLC number. When comparing quotes, normalise everyone to HPLC before you judge price.
The Three-Curcuminoid Fingerprint
HPLC’s real value is not just the number — it is the fingerprint. A genuine turmeric extract shows three resolved curcuminoid peaks in a natural ratio (curcumin dominant, then demethoxycurcumin, then bisdemethoxycurcumin). This pattern is an authenticity signal:
- All three peaks present in plant-like proportions → consistent with a genuine extract.
- A single sharp peak with the other two largely absent → a red flag for synthetic curcumin substituted for the plant complex.
We cover this failure mode in turmeric adulteration & synthetic curcumin.
How to Read a Turmeric Extract CoA
On a Certificate of Analysis, check these in order:
- What is assayed — “total curcuminoids” (good) vs an unspecified “curcumin”.
- The method — HPLC stated next to the assay, ideally with a chromatogram or per-curcuminoid breakdown.
- The reference — against a curcuminoid standard, with the wavelength/column noted for HPLC.
- Consistency with identity — the same three-curcuminoid profile appearing in the identification test.
Why It Matters Commercially
Beyond authenticity, the method drives money and compliance. Paying for “95%” that is really a UV figure means paying for fewer actual curcuminoids than you think. And a label that states a standardised value your supplier measured by UV, audited later by an HPLC-equipped customer or regulator, is a compliance exposure. Specifying HPLC up front removes both risks. For the full purchasing workflow, see the turmeric extract buyer’s guide.
SV Botanica’s 95% grade is assayed by HPLC for total curcuminoids, with the curcuminoid profile available per batch — so buyers are never left to reconcile a UV headline against an HPLC reality.
Need an HPLC-Assayed Curcumin 95%?
95% total curcuminoids by HPLC · three-curcuminoid fingerprint · per-batch chromatogram on request · samples for qualified buyers