Two suppliers quote “Bacopa 20%.” One tested it by UV spectrophotometry, the other by HPLC. They are not the same 20% — and treating them as interchangeable is the most common way buyers overpay for, or under-spec, bacopa extract. Here is what each method measures and how to compare quotes on equal terms.
Two Different Questions, Two Different Methods
A bacoside assay can answer one of two different questions, and the method determines which:
- UV / spectrophotometric assay measures the total bacoside-rich saponin fraction by its colour reaction or absorbance. It reads broader and higher, is fast and inexpensive, and is the common trade method for standardised bacopa grades.
- HPLC assay separates and quantifies specific, named bacosides — typically reported as bacoside A or as the sum of defined peaks such as bacopaside II. It reads lower but is compound-specific and far harder to inflate.
Why the Numbers Differ
UV captures everything in the sample that responds to the assay chemistry, including co-extracted saponins and related compounds that are not the target bacosides. HPLC only counts the peaks it can identify and integrate against reference standards. As a result, a material labelled 20% by UV can read materially lower — often in the high single digits to low teens — when re-tested as bacoside A by HPLC. Neither number is “wrong”; they are answers to different questions. The error is comparing a UV figure from one supplier against an HPLC figure from another and concluding one is cheaper.
What “Bacoside A” Actually Means
Adding to the confusion, bacoside A is itself a defined mixture, not a single molecule — classically comprising bacoside A3, bacopaside II, bacopasaponin C and a jujubogenin-isomer glycoside. A rigorous HPLC spec will state which markers are summed. If a CoA says “bacosides by HPLC” without naming the peaks, ask what is being integrated.
Which Method You Should Specify
- Clinical alignment — if your positioning references specific human trials, match the standardisation basis those studies used.
- Label & monograph claims — a defined-profile label or a pharmacopoeial monograph generally calls for HPLC.
- Cost-managed blends — a UV-standardised grade may be entirely appropriate for a multi-herb formula, provided every supplier is quoted on UV.
How to Compare Quotes Apples-to-Apples
Three rules prevent almost every mismatch:
- State the method in your RFQ — “20% bacosides by UV” or “bacoside A by HPLC,” not just “20%.”
- Require the method on the CoA — a percentage without a method is not a specification.
- Normalise before comparing — if one quote is UV and another HPLC, ask both suppliers for the same method before you judge price.
SV Botanica’s Approach
Our stock grades — 20%, 40% and 50% bacosides — are assayed by UV, the standard trade basis, and identified by TLC/HPTLC. On the same herb material we make an HPLC bacoside A test report available per batch, so a buyer who needs a compound-specific profile is never left with the UV number alone. That lets you hold one supplier accountable on both methods rather than reconciling numbers across vendors.
Reading the CoA
On a complete bacopa CoA you should see the botanical name (Bacopa monnieri), the bacoside result with its method, identity by TLC/HPTLC, loss on drying, ash, particle size, heavy metals by ICP-MS and a full microbial panel. If the assay method is missing, treat the percentage as indicative only. For the full document checklist, see the Brahmi extract buyer’s guide.
Need a Defined Bacoside Profile?
UV-standardised 20/40/50% grades · HPLC bacoside A test report per batch · TLC/HPTLC identity · batch-specific CoA