- Bromophenol blue
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ImageFile=BromophenolBlue.svg
ImageSize=250
IUPACName=2,6-dibromo-4- [3-(3,5-dibromo-4-hydroxyphenyl)-1,1-dioxo-3-benzo [c] oxathiolyl] phenol
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Section1= Chembox Identifiers
CASNo=115-39-9
PubChem=8272
SMILES=C1=CC=C2C(=C1)C(OS2(=O)=O)(C3=CC(=C(C(=C3)Br)O)Br)C4=CC(=C(C(=C4)Br)O)Br
Section2= Chembox Properties
C=19|H=10|Br=4|O=5|S=1
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Section3= Chembox Hazards
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Autoignition=Bromophenol blue ("3',3",5',5"-tetrabromophenolsulfonphthalein") is an acid-base indicator whose useful range as an indicator lies between
pH 3.0 and 4.6. It changes from yellow at pH 3.0 to purple at pH 4.6; this reaction is reversible.Bromophenol blue is also used as a color marker to monitor the process of
agarose gel electrophoresis and polyacrylamide gel electrophoresis. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction asDNA orprotein in a gel; the rate at which it migrates varies according to gel density and buffer composition, but in a typical 1%agarose gel inTAE buffer orTBE buffer , bromophenol blue migrates at the same rate as a DNA fragment of approximately 500base pair s.Xylene cyanol andOrange G may also be used for this purpose.cite web |url=http://www.methodbook.net/dna/agarogel.html |title=Agarose gel electrophoresis (basic method) |accessdate=2008-04-07 |format= |work=]The bromophenol blue is also used as a dye. At neutral pH, the dye absorbs red light most strongly and transmits blue light. Solutions of the dye therefore are blue. At low pH, the dye absorbs ultraviolet and blue light most strongly and appears yellow in solution. In solution at pH 3.6 (in the middle of the transition range of this pH indicator) obtained by dissolution in water without any pH adjustment, bromophenol blue has a characteristic green red color. This phenomenon is called dichromatic colour.cite journal |author=Kreft S, Kreft M |title=Physicochemical and physiological basis of dichromatic colour |journal=Naturwissenschaften |volume=94 |issue=11 |pages=935–9 |year=2007 |pmid=17534588 |doi=10.1007/s00114-007-0272-9]
Bromophenol blue is commonly used in entry-level lab courses to stain proteins in wet-mount slides.cite web |url=http://genetics.mgh.harvard.edu/szostakweb/protocols/protein_page/index.html |title=PROTEIN GEL ELECTROPHORESIS |accessdate=2008-04-07 |format= |work=]
References
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