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E1385 Sigma-Aldrich

Ethidium bromide solution

BioReagent, for molecular biology, 500 μg/mL in H2O

Synonym: 3,8-Diamino-5-ethyl-6-phenylphenanthridinium bromide, EtBr, Homidium bromide

  • CAS Number 1239-45-8

  • Empirical Formula (Hill Notation) C21H20BrN3

  • Molecular Weight 394.31

  •  Beilstein/REAXYS Number 3642536

  •  MDL number MFCD00011724

  •  PubChem Substance ID 24894408



Related Categories Agarose Blends for Electrophoresis, Biochemicals and Reagents, Core Bioreagents, Ethidium Bromide, Fluorescent Probes, Labels, Particles and Stains,
grade   for molecular biology
product line   BioReagent
concentration   500 μg/mL in H2O
suitability   suitable for gel electrophoresis



Ethidium bromide solution has been used to deplete mtDNA to investigate mitochondrial damage signals in autophagy. It has also been used to detect DNA damage using comet assay.

Ethidium bromide (EtBr) is the most commonly used nucleic acid stain for PAGE or agarose gel electrophoresis. The fluorescence of EtBr increases 21-fold upon binding to double-stranded RNA and 25-fold on binding double-stranded DNA so that destaining the background is not necessary with a low stain concentration (10 μg/ml). Ethidium bromide has been used in a number of fluorimetric assays for nucleic acids. It has been shown to bind to single-stranded DNA (although not as strongly) and triple-stranded DNA. Because of its ability to bind to DNA, EtBr is an inhibitor of DNA polymerase.


5 mL in glass bottle

Biochem/physiol Actions

Ethidium bromide intercalates double-stranded DNA and RNA and acts as a frameshift mutagen. It can also be used in conjunction with acridine orange to differentiate between viable, apoptotic and necrotic cells.


For staining a gel after electrophoresis, dilute a sample of the stock solution to 0.5 μg/ml with water and incubate the gel for 15-30 min. Destaining is usually not needed but can be carried out in water for 15 min if decreased background is necessary. The DNA bands can then be detected on a UV light box (254 nm wavelength). Ethidium bromide can also be incorporated into the gel and running buffer at 0.5 μg/ml and visualized immediately after electrophoresis.

Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 


Certificate of Analysis


Certificate of Origin

Protocols & Articles


Ethidium Bromide

Synonyms: 3,8-Diamino-5-ethyl-6-phenylphenanthridinium bromide; 2,7-Diamino-10-ethyl-9-phenylphenanthridinium bromide; Homidium Bromide; Dromilac; EtBr
Keywords: Absorption, Electrophoresis, Gel electrophoresis, Melting, Molecular biology, Veterinary

Peer-Reviewed Papers


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Z361569 Extractor for Ethidium Bromide Decontamination, includes storage cap and adhesive label For EtBr removal from solutions
57610-U Rezorian A161 Cartridge, size 1 mL For EtBr removal from solutions
01494 Nancy-520, suitable for RT-PCR, ≥97.0% (HPCE) Less mutagenic alternative to EtBr
E7637 Ethidium bromide, BioReagent, for molecular biology, powder

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