Two extracts can share a headline percentage and still be different materials.
A botanical extract specification tells you three things: what the material is, how its strength is expressed, and how that figure was measured. If any of the three differs, two offers with the same number on the front page are not offers for the same ingredient.
Here are seven checks to make before you compare suppliers or request a quote, with examples from our own catalogue and technical documents, followed by the short brief that lets a supplier answer precisely.
01 / THE MATERIAL
Which plant, and which part of it?
A specification starts with identity. European medicines guidance on herbal preparations asks first for “a statement of the botanical source, and the type of preparation (e.g. dry or liquid extract)”.1 Root, leaf, seed, bark, fruit and mushroom fruiting body are different starting materials, and one plant can supply more than one of them.
Our catalogue lists the source part and a powder description for every extract. Rhodiola Rosea Extract, for example, is described as a light-brown fine powder made from root. Our documented Bamboo Extract grade is a stem-derived Moso Bamboo powder.
Check: the botanical name, the plant part and the physical description.
02 / THE FIGURE
What does the percentage refer to?
A percentage always refers to something: one named compound, a defined group of compounds, or a substance expressed in a particular chemical form. The headline rarely says which.
Two examples from our documents. “75% bamboo silica”: our documented Bamboo Extract grade specifies silicon dioxide (SiO₂) at ≥75.0%. The percentage refers to silicon dioxide, not to elemental silicon and not to an extract ratio. “3% rosavins and 1% salidroside”: this is one conventional Rhodiola rosea specification. Total rosavins comprises rosavin, rosarin and rosin; salidroside is a separate constituent with its own figure.
Check: which compound or group is being counted, and what the result is expressed as.
03 / THE METHOD
How was the figure measured?
A figure can only be compared with another figure obtained by the same method. A 2023 review by authors from the American Botanical Council and partner organisations explains why: concentrations obtained by spectrophotometry “are often higher than the results from other quantitative methods due to interference from nontarget analytes that absorb at the wavelength of interest”. For milk thistle extract it reports silymarin concentrations of generally between 30% and 65% by HPLC-UV and 65–80% using spectrophotometric tests, and it concludes that declaring the methodology behind a quantitative result “should become standard industry practice”.4
Our cranberry extract shows what a complete statement looks like. It is specified at 30% or more total soluble proanthocyanidins (PACs) by BL-DMAC / UV-Vis, expressed as procyanidin A2 equivalents. The assay uses procyanidin A2 as its reference standard and measures absorbance at 640 nm; it does not establish isolated A-type PAC purity. The bamboo figure above is measured by ICP-OES.
Check: the analytical method and, where it forms part of the assay, the reference standard. Compare these as well as the number.
04 / RATIO OR ASSAY
Is it a ratio, an assay, or both?
An extract ratio and an assay answer different questions. European medicines guidance defines the drug extract ratio (DER) as “the ratio between the quantity of herbal substance used in the manufacture of a herbal preparation and the quantity of herbal preparation obtained”.2 It describes how much plant material went into the extract, not how much of any compound came out. A paper by authors from the United States Pharmacopeia puts it plainly: “Perhaps the most common misconception regarding Plant to Extract ratios is that a higher ratio represents a stronger, and therefore better extract.”5
Two details are worth asking about. The same guidance separates the genuine, or native, extract, meaning the preparation without excipients, from the finished extract with its carrier;2 a ratio quoted for one is not the ratio of the other. And in that guidance “standardised” has a narrow meaning: adjusted to a defined content of constituents with known therapeutic activity.3 On a commercial document, ask what the word is being used to mean.
Some extracts are specified by an assay, some by a ratio and some by both. Our quotation form for Elderberry Extract, for instance, asks for the anthocyanin target and assay method, the preferred extract ratio, and any solubility or carrier requirements.
Check: whether you need a compound level, a ratio or both, and whether a quoted ratio refers to the native extract or to the finished powder.
05 / CARRIER AND FORM
What else is in the powder?
An extract powder may contain a carrier as well as the native extract. The guidance cited above treats carrier substances as excipients that “may be part of herbal preparations”, and it expects excipients in the final extract to be specified.12 A carrier dilutes the native extract, and it changes how the powder behaves in use. Our Bamboo Extract grade contains a maltodextrin carrier and is highly dispersible in water.
Check: any carrier, dispersibility or solubility, and storage requirements. If your formulation needs something different, say so: carrier and solubility modification are among the customisation options we discuss.
06 / THE DOCUMENT
Specification, COA or TDS?
Three documents do three jobs. A product specification describes the stated requirements for a grade: in the words of the European guidance, “a list of tests, references to analytical or biological procedures, and appropriate acceptance criteria”.1 A Certificate of Analysis (COA) reports results for an identified batch; the World Health Organization’s model certificate “lists tests performed on a particular sample with the results obtained and the acceptance criteria applied”.6 A Technical Data Sheet (TDS) provides formulation guidance and does not replace the specification or the batch COA.
Check: ask for the specification of the grade you are evaluating and the COA of the batch on offer, and say which other documents your technical team needs.
07 / YOUR MARKET
Which limits apply where the product will be sold?
Contaminant limits come from the law of the market in which the finished product is sold. For food supplements, the European Union and Great Britain currently set the same maximum levels for three metals: lead 3.0 mg/kg, cadmium 1.0 mg/kg and mercury 0.10 mg/kg, with a higher cadmium level of 3.0 mg/kg for supplements made largely from dried seaweed, products derived from seaweed or dried bivalve molluscs. For supplements containing botanicals they also limit polycyclic aromatic hydrocarbons: 10.0 µg/kg for benzo(a)pyrene and 50.0 µg/kg for the sum of four.78 These levels are set for the supplement as placed on the market, or “as sold”; what they mean for an ingredient depends on how much of it the finished product contains.
Other rules work differently. Pesticide maximum residue levels are set for raw commodities and are applied to processed products, such as extracts, through processing factors.9 The solvents permitted for extraction in food production, and residue limits for certain uses, are listed in law.10 A specification that suits one market or application may not suit another.
Check: state your destination market and intended application at the start, so that the specification and documents can be discussed for it.
WHAT TO SEND
A short brief gets a precise answer
For an accurate quote or sample discussion, send:
- the ingredient, and the plant part if more than one is offered;
- your target specification: the compound and level, the extract ratio, or both;
- the assay method you require, if you have one;
- any carrier, solubility or other technical requirements;
- your estimated quantity;
- your destination market;
- your name, company and contact details.
Specification ranges in our catalogue are references. Feasibility, availability and price are confirmed with your quotation. You can also request a sample for ingredient evaluation and tell us which technical documents you need, such as a specification sheet or Certificate of Analysis; our team confirms sample availability and the documentation available for the selected grade.
Product examples are taken from YOHOLIFE® specifications and technical documents; confirm the selected grade and its batch COA when enquiring. Sources 1 to 3 and 6 were written for medicines and are cited here for their definitions. Legal references were checked on 11 November 2026 and are given for orientation, not as regulatory advice.
