Wholesome in bulk™ Quercetin Powder
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Bulk Quercetin Powder for Supplement Manufacturing
Quercetin powder is a yellow flavonol powder made from plant sources, most often the flower buds of Sophora japonica (now Styphnolobium japonicum). Suppliers extract rutin from the buds and split off its sugars to give quercetin. It is traded mainly as quercetin dihydrate, with purity measured by HPLC. We supply it in bulk to supplement brands, contract manufacturers, and formulators. You can request testing documents and samples on the quote form.
A defined flavonol with clear identity tests
Quercetin is one named compound, so you can specify it like a fine chemical. The CAS number, the hydrate form, and an HPLC assay tell you what each lot holds. That gives buyers and quality teams a shared basis for comparing suppliers.
Defined chemical identity
Quercetin is C15H10O7, a flavonol with five hydroxyl groups. Identity is confirmed by HPLC retention time against a reference standard, often backed by an infrared or UV spectrum.
Dihydrate or anhydrous
Most bulk quercetin is the dihydrate, which carries two water molecules for each quercetin molecule. Anhydrous quercetin is also traded, and the CAS number on the COA tells you which form you have.
Assay by HPLC
Common grades are NLT 95% and NLT 98% quercetin by HPLC. Ask whether the result is on an as is or anhydrous basis, because water content moves the number.
Botanical starting material
Commercial quercetin usually starts as rutin from Sophora japonica flower buds. Suppliers split the rutin into quercetin and sugars, then purify and dry the powder.
Fine yellow powder
Spec sheets describe a yellow powder that passes an 80 mesh screen. The melting point on published specs is about 305 to 315 °C.
Low water solubility
Quercetin dissolves poorly in water and better in ethanol. It fits capsules and tablets most easily, and drink formats need dispersion work.
Where formulators use quercetin powder
Quercetin fits dry, measured formats where fill weight and particle size are controlled, including:
- Capsules
- Compressed tablets
- Single ingredient powders
- Multiple ingredient capsule blends
- Flavonoid and botanical blends
- Vitamin and mineral blends
- Powdered drink mixes, after dispersion trials
- Private label programs
Plan fill weights from the assay and form on each COA. Dihydrate and anhydrous quercetin are not interchangeable gram for gram, so recalculate your serving math whenever you change forms or suppliers.
What to check before you buy quercetin
Two powders sold as quercetin can differ in hydrate form, assay basis, and starting material. Review these points together, and ask for lot documents before you approve a supplier.
Hydrate form and CAS number
Confirm dihydrate (CAS 6151-25-3) or anhydrous (CAS 117-39-5) on both the specification and the certificate of analysis (COA). The form changes how much quercetin each gram holds.
Assay method and basis
Ask for quercetin by HPLC and whether the result is as is or on an anhydrous basis. A UV result for total flavonoids is a different, broader measure.
Water content
In theory, a dihydrate holds about 10.7% water by weight. Published specs allow about 8.5% to 12.5%, so a result far outside that range is worth a question.
Starting material and solvents
Ask for the plant source and part, usually Sophora japonica flower buds, and the solvents used. Request residual solvent results by GC to USP <467>.
Contaminant limits
Check lead, arsenic, cadmium, and mercury by ICP-MS, plus microbial limits by USP methods. Compare each limit with your own finished product specification.
SDS and shipping class
Some safety data sheets list quercetin under transport hazard class 6.1. Ask for the supplier's SDS so your warehouse and freight forwarder can plan.
Dihydrate math: By molecular weight, quercetin dihydrate is about 89% quercetin and 11% water. So 1,000 mg of dihydrate at full assay holds about 893 mg of quercetin. If your label states quercetin per serving, base it on the COA assay and form, and confirm it with your own finished product testing.
Typical specification for quercetin dihydrate
These values reflect published spec sheets for quercetin dihydrate. Final figures come from the specification sheet and COA for your lot. NLT means not less than, and NMT means not more than.
| Parameter | Specification | Method |
|---|---|---|
| Identity | Quercetin dihydrate, C15H10O7·2H2O, CAS 6151-25-3 | HPLC retention time against a reference standard |
| Botanical source | Sophora japonica L. flower buds, via rutin | Supplier declaration |
| Appearance | Yellow powder | Visual |
| Assay, quercetin | NLT 95.0%, basis stated on the COA | HPLC |
| Water or loss on drying | 8.5% to 12.5% | USP <921> or USP <731> |
| Melting point | 305 to 315 °C | USP <741> |
| Particle size | NLT 95% through 80 mesh | USP <786> |
| Ash | NMT 0.5% | USP <561> |
| Residual solvents | Meets USP <467> | GC |
| Lead | NMT 3.0 ppm | ICP-MS |
| Arsenic | NMT 1.0 ppm | ICP-MS |
| Cadmium | NMT 1.0 ppm | ICP-MS |
| Mercury | NMT 0.1 ppm | ICP-MS |
| Total aerobic count | NMT 1,000 cfu/g | USP <61> or <2021> |
| Yeast and mold | NMT 100 cfu/g | USP <61> or <2021> |
| E. coli and Salmonella | Negative | USP <62> or <2022> |
| Shelf life | 24 months, unopened, in tight light resistant packaging | Stability data |
Quality standards for quercetin
Quercetin dihydrate has a monograph in the European and British Pharmacopoeias, and the USP covers its main starting materials. Together they set clear numbers for assay, water, and related compounds.
Pharmacopoeial quercetin dihydrate
Canada's natural products monograph for quercetin names the Ph. Eur. and BP quercetin dihydrate monograph as an optional quality standard. Australia's TGA compositional guideline sets HPLC assay at 98.0 to 102.0% on the anhydrous basis. It sets water at 9.0 to 12.0%, sulfated ash at NMT 0.2%, and heavy metals at NMT 10 ppm.
Related substances by HPLC
The TGA guideline caps any single related substance at NMT 1.0% and the total at NMT 2.0%, by HPLC. Sophora buds also carry kaempferol and isorhamnetin glycosides, which the USP counts in its flavonol totals. Hydrolysis can carry those flavonols into the finished powder, so a related substances result tells you more than a bare assay.
Monographs for the starting material
USP Japanese Sophora Flower Bud requires 13 to 25% rutin and 0.3 to 1.0% quercetin on the dried basis. The opened flower carries less, at 6.5 to 13% rutin. The Ph. Eur. rutoside trihydrate monograph sets 95.0 to 101.0% on the anhydrous basis and caps quercetin as an impurity at NMT 2.0%.
How identity is confirmed
Identity rests on an HPLC retention time match to a reference standard, backed by an infrared spectrum or TLC. The USP quercetin reference standard is the dihydrate, C15H10O7·2H2O, with a molecular weight of 338.27. DNA methods do not apply to a purified compound. Some COAs also confirm that no free sugars remain, a sign that the sugars split from rutin were washed out.
Contaminant limits to build on
USP <2232> sets component limits of 0.5 µg/g for lead and cadmium, for intakes up to 10 g a day. Published quercetin sheets range from NMT 2 ppm lead down to NMT 0.5 ppm by ICP-MS. Older specs still list total heavy metals at NMT 10 ppm, a group test that does not name each metal.
Sourcing and processing practices for quercetin
Quercetin is made from a plant glycoside in a few chemical steps. Each step leaves a trace that a good specification asks about.
Know the hydrolysis step
Quercetin is commonly made by boiling rutin in dilute hydrochloric or sulfuric acid for 2 to 3 hours. The crude cake is washed with hot water until neutral, then refined with methanol and water. Ask which acid and solvents were used, and request a GC result for methanol under USP <467>.
Know the plant and the country
Rutin for quercetin comes from Japanese pagoda tree buds or from fava d'anta fruit, a Dimorphandra species from Brazil. In Brazil much of that fruit is gathered from wild trees by local communities. Ask for the species, the country, and the harvest model behind your rutin.
State how water is measured
A dihydrate holds about 10.7% water by formula, and the TGA range is 9.0 to 12.0%. Karl Fischer titration measures that crystal water directly. Loss on drying can give a different figure, so write the method next to the limit.
Keep wet steps acidic and short
Heated in water, quercetin breaks down fastest under weakly basic and oxidizing conditions. Protocatechuic acid is one of the breakdown products. Keep any wet granulation or liquid step at neutral or acidic pH, and keep heating time short.
Choose the physical form early
Standard quercetin is a light, fluffy powder, and one COA shows a bulk density of 0.14 g/mL. Granular grades are made to set mesh bands, with NLT 0.40 g/mL bulk density. Choose the form for your press or encapsulator before you qualify a supplier.
Formulator tips for quercetin
Use these points when you set label figures, fill weights, and incoming tests. Most figures below come from pharmacopoeial texts and published supplier sheets.
- State the form on the label and in your test method. Independent labs test quercetin in the form the label names, and some report an unnamed form as anhydrous.
- Convert an anhydrous basis assay before you calculate fill. A lot that reads 98.0% on the anhydrous basis and holds 10.7% water contains about 87.5% quercetin as is.
- Plan capsule fill from bulk density. At 0.14 g/mL, 500 mg of standard powder takes about 3.6 mL; at 0.40 g/mL, a granular grade takes about 1.25 mL. Ask for bulk and tapped density on the COA.
- If you switch from rutin, use molecular weights. Quercetin makes up about 45% of rutin trihydrate by weight (302.24 divided by 665).
- Ask for related substances as well as assay. A 95% assay leaves up to 5% of other material, and an HPLC impurity profile shows what it is.
- Run tablet disintegration early. Quercetin is practically insoluble in water, so test breakup with your binder and disintegrant before you scale up.
- Set an incoming test plan. Run HPLC identity and assay with the basis stated, water by Karl Fischer, and lead and cadmium by ICP-MS on every lot. Add residual methanol by GC for each new supplier or process change.
- Recheck water and assay at the retest date. A shift in water moves the as is assay even when no quercetin has been lost.
Helping shoppers read a quercetin label
Customer service teams hear the same few questions about quercetin labels. These answers stick to what the ingredient is and how it is labeled.
Dihydrate or anhydrous
A label may say quercetin (as quercetin dihydrate) or anhydrous quercetin. The dihydrate carries water inside its crystals, so about 89% of its weight is quercetin. Both describe the same molecule, and the form tells you which number the label uses.
Where it comes from
Quercetin is usually made from rutin taken from the flower buds of the Japanese pagoda tree, Styphnolobium japonicum. Some is made from the fruit of a Brazilian tree called fava d'anta. The finished powder is one purified compound, so labels name quercetin and may add the source.
Independent quality programs
Programs such as the USP Dietary Supplement Verification Program and NSF/ANSI 173 certification check finished products against their labels and contaminant limits. Independent labs measure quercetin by HPLC and compare the result with the form named on the label.
Normal look and home storage
Quercetin is a yellow powder and can leave a yellow mark on hands or surfaces. Keep the bottle tightly closed, away from light, heat, and moisture. The European Pharmacopoeia calls for a light resistant container.
Storage and handling for bulk quercetin
Quercetin stays in spec longest when it is sealed, dry, and away from light. Published specs call for tight, light resistant containers kept away from heat and moisture.
Keep it sealed
Close the inner liner after each use and press out the air. Sealed packaging also keeps the water content of a dihydrate steady.
Keep away from light
Leave the powder in its original opaque packaging, in a cool and dry room. Light and heat can shift color and assay over time.
Control dust
Fine flavonol powders dust easily and stain yellow. Use local dust extraction, gloves, and safety glasses, as the SDS directs.
Rotate stock
Record the lot number and retest date for each bag. Send older lots to production first.
Quercetin buyer FAQ
Quick answers to the questions procurement and quality teams ask most.
What is the difference between quercetin dihydrate and anhydrous quercetin?
Quercetin dihydrate carries two water molecules for each quercetin molecule, while anhydrous quercetin has that water removed. By molecular weight the dihydrate is about 89% quercetin. The two forms have different CAS numbers, so check the COA for the form.
Is quercetin dihydrate the same as dihydroquercetin?
No. Quercetin dihydrate is quercetin with water of crystallization, CAS 6151-25-3. Dihydroquercetin, also called taxifolin, is a different molecule with CAS 480-18-2, so write the full name and CAS number on purchase orders.
Is isoquercetin the same as quercetin?
No. Isoquercetin is quercetin bonded to a single sugar unit, and rutin is quercetin bonded to a unit of two sugars. They are separate ingredients with their own specs, so do not swap them gram for gram.
Which purity grade should I choose?
Most bulk listings offer NLT 95% quercetin by HPLC, and 98% grades are also sold. Choose based on your label target, capsule size, and cost per finished serving. Ask the supplier to state the assay basis.
Does quercetin dissolve in water?
Only slightly. Quercetin dissolves poorly in water and better in ethanol, so in drinks it tends to disperse rather than dissolve. Run suspension and settling trials before you commit to a beverage format.
Is there a pharmacopoeial standard for quercetin?
Yes. The European and British Pharmacopoeias include a quercetin dihydrate monograph, and Canadian regulators cite it as an optional standard. Australia's TGA guideline sets HPLC assay at 98.0 to 102.0% on the anhydrous basis and water at 9.0 to 12.0%.
What documents can I get with an order?
A certificate of analysis (COA) and a specification sheet ship with every order. An allergen statement and a safety data sheet may also be available, depending on the lot in inventory. Contact us to request them.
Can I get a sample before a bulk order?
You can request one by choosing sample options on the quote form. We will confirm availability, size, and timing.
How should I store an opened bag?
Close the liner, press out the air, and keep the bag in a cool, dry place away from light. Use the powder within the shelf life shown on the COA.
Request a quote for bulk quercetin
Tell us the form, grade, quantity, and timing you need. We will reply with current pricing. Select testing documents and sample options on the quote form.
Order QuercetinBulk orders: Choose a pack size above, or use the quote form for larger volumes, testing documents, and sample options. We serve supplement brands, contract manufacturers, product developers, and formulators.
This bulk ingredient is sold for further manufacturing and formulation. The information on this page describes the ingredient and how commercial buyers evaluate it. It is not medical advice. Each finished product brand is responsible for its own labeling and product claims.
