Molekula
Fluorescein
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 2000 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Fluorescein is a fluorescent dye used in biological staining, medical diagnostics, and environmental tracing. It also serves as an adsorption indicator in silver nitrate titrations, a colorant for cosmetics and household cleaners, and a forensic reagent for detecting trace blood. It exhibits strong green fluorescence when excited by blue light. Available with CAS number 2321-07-5, molecular formula C20H12O5, and molecular weight 332.31 g/mol. Store at 2 to 8 °C. Signal word: Warning. Molekula supplies Fluorescein from research to bulk quantities with full documentation and ISO 9001:2015 traceability.
Example image for illustration only. Other packaging and pack sizes are available.
Pricing & pack sizes
These pack sizes aren't a limit. Molekula manufactures, sources and repacks to order — if you need 500 kg and only see 1 kg listed, . We quote from grams to multi-tonne.
Need a different size? Add the nearest pack and change the size in your basket — we price it at the same rate per unit.
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100 g — £30.90 per pack ex VAT · £37.08 inc. VAT
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500 g — £62.30 per pack ex VAT · £74.76 inc. VAT
Need a different quantity or pack?
Tell us how much you need and when — drums, IBCs, sacks or a one-off bulk lot. We'll manufacture or source it and come back with a price.
Prices exclude VAT/sales tax and shipping.
Specifications
| Property | Value |
|---|---|
| Appearance | Orange/ red crystalline powder |
| Loss on Drying | ≤5.0% |
| Specific Absorbance (E 1%/1cm) | 2400 - 2600 |
| Wavelength of maximum absorption (0.1N NaOH) | 490 - 492nm |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | 2 to 8 °C |
| Acidity | Acid |
Literature values
Published physical properties of the substance, not batch specifications.
| Property | Value |
|---|---|
| Appearance | Red, orthorhombic prisms |
| Melting Point | 315 °C (decomposes) |
| Water Solubility | 50 mg/L at 20 °C |
| Solubility (other solvents) | Slightly soluble in ethanol, diethyl ether; very soluble in acetone; soluble in pyridine, methanol |
Source: PubChem CID 16850 (HSDB)
Identification
| Property | Value |
|---|---|
| SKU | 36797905 |
| CAS Number | 2321-07-5 |
| IUPAC Name | 3',6'-dihydroxyspiro[2-benzofuran-3,9'-xanthene]-1-one |
| EC Number | 219-031-8 |
| Molecular Formula | C20H12O5 |
| Molecular Weight | 332.31 |
| Exact Mass | 332.0685 |
| SMILES | C1=CC=C2C(=C1)C(=O)OC23C4=C(C=C(C=C4)O)OC5=C3C=CC(=C5)O |
| InChIKey | GNBHRKFJIUUOQI-UHFFFAOYSA-N |
| InChI | InChI=1S/C20H12O5/c21-11-5-7-15-17(9-11)24-18-10-12(22)6-8-16(18)20(15)14-4-2-1-3-13(14)19(23)25-20/h1-10,21-22H |
| PubChem CID | 16850 |
| REACH Code | Y113 |
| TSCA Listed | Yes |
| HTS Code | 3212.90.00.50 |
| Tariff Code | 3212900000 |
Safety & GHS
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Health Hazard
GHS07
Hazard statements
- H319 Causes serious eye irritation
Precautionary statements
- P264 Wash thoroughly after handling
- P280 Wear protective gloves/protective clothing/eye protection/face protection
- P305+351+338 IF IN EYES: Rinse with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing
- P337+313 If eye irritation persists get medical advice/attention
Documents
Safety Data Sheets (SDS)
Available in English, French, German, Italian, Portuguese, Spanish.
Certificate of Analysis (CoA) by batch
Enter a lot or batch number to retrieve the CoA for that specific batch. We can generate one from spec data if no PDF is on file.
Synonyms
- 3,6-Fluorandiol
- 3',6'-Dihydroxyfluoran
- D and C Yellow No. 7
- D&C Yellow No. 7
- Fluorescein acid
- Fluoresceine
- Japan Yellow 201
- Resorcinolphthalein
- Solvent Yellow 94
- Yellow fluorescein
Frequently asked questions
What is fluorescein used for?
Fluorescein is commonly used as a fluorescent dye in biological staining, medical imaging, and environmental tracing applications.
What is the chemical formula and molecular weight of fluorescein?
The formula is C20H12O5 with a molecular weight of 332.31 g/mol.
How should fluorescein be stored?
Fluorescein should be stored at 2 to 8 °C, protected from light and moisture.
What grade of fluorescein is available?
Molekula supplies fluorescein in analytical grade, suitable for laboratory and research use.
Can Molekula supply fluorescein in bulk?
Yes, Molekula can supply fluorescein in bulk quantities—please contact our sales team for pricing and availability.
What documentation comes with a fluorescein order?
Each order includes a Certificate of Analysis (CoA) and safety data sheet (SDS) with the shipment.
Ready to order or need a custom pack?
Tell us the product, grade, and quantity — Molekula usually responds within one working day with pricing and lead time.