46955 Sigma-Aldrich


for fluorescence, free acid

Synonym: Acid Yellow 73

  • CAS Number 2321-07-5

  • Empirical Formula (Hill Notation) C20H12O5

  • Molecular Weight 332.31

  •  Colour Index Number 45350

  •  Beilstein/REAXYS Number 94324

  •  EC Number 219-031-8

  •  MDL number MFCD00005050

  •  PubChem Substance ID 329757275

  •  NACRES NA.32



Related Categories Adsorption Indicators, Analytical Reagents, Analytical/Chromatography, Biochemicals and Reagents, Detection,
Quality Level   100
grade   for fluorescence
application(s)   titration: suitable
fluorescence   λex 490 nm; λem 514 nm in 0.1 M Tris pH 8.0
suitability   suitable for fluorescence
storage temp.   room temp
SMILES string   Oc1ccc2c(Oc3cc(O)ccc3C24OC(=O)c5ccccc45)c1
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
Gene Information   human ... PTPN1(5770), PTPRF(5792)


General description

Fluorescein dye is the most commonly used fluorescent probe. It is used to stain epithelial defects and analyse the integrity of corneal epithelium. Fluorescein is used in the diagnosis of corneal perforation. Oral or intravenous fluorescein is used in fluorescein angiography to detect diabetic retinopathy and choroidal neovascular membrane.


Fluorescein has been used:
• in the permeability assay of Caco-2 cells
• to test its suitability to serve as lifetime fluorescence standards
• as a fluorophore for the fast recovery of fluorescence peaks and fluorophore concentration in the presence of hemoglobin
• as a fluorescent probe in oxygen radical absorbance capacity (ORAC) assay

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

Please Enter a Lot Number

Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
What is Product 46955,Fluorescein, soluble in?
According to the chemicals encyclopedia published by the Royal Society of Chemistry : 13th Edition, Fluorescein is soluble in hot alcohol and glacial acetic acid. Also, it is soluble in alkali hydroxides or carbonates. This product is insoluble in water, benzene, chloroform and ether.
How should Product 46955, Fluorescein, be stored?
We recommend storing this product at room temperature.
What is the dye content of Product 46955, Fluorescein?
According to our supplier, the dye content of pure Fluorescein is a minimum of 90%. We do not test the purity of this product since it is not one of our specifications.
How do I find price and availability?
There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 or view local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
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Protocols & Articles


Fluorescence Quenching Microscopy: Imaging Two-Dimensional Materials

Alane Lim and Jiaxing Huang* Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA *Email:
Keywords: Chemical vapor deposition, Deposition, Diffraction, Materials Science, Microscopy, Optical microscopy, Scanning electron microscopy, Solvents, Spectroscopy, Spin coating

Peer-Reviewed Papers


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