Bromophenol blue
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220847226
2008-06-21T22:14:51Z
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{{Chembox new
|ImageFile=BromophenolBlue.svg
|ImageSize=250
|IUPACName=2,6-dibromo-4-[3-(3,5-dibromo-4-hydroxyphenyl)-1,1-dioxo-3-benzo[c]oxathiolyl]phenol
|OtherNames=
|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
| Formula=C<sub>19</sub>H<sub>10</sub>Br<sub>4</sub>O<sub>5</sub>S
| MolarMass=669.9607
| Appearance=
| Density=
| MeltingPt=
| BoilingPt=
| Solubility=
}}
|Section3= {{Chembox Hazards
| MainHazards=
| FlashPt=
| Autoignition=
}}
}}
{{pH_indicator_template|indicator_name=Bromophenol blue|low_pH=3.0|high_pH=4.6|low_pH_color=yellow|high_pH_color=purple}}
'''Bromophenol blue''' (''3',3",5',5"-tetrabromophenolsulfonphthalein'') is an acid-base [[pH indicator|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 [[SDS PAGE|polyacrylamide gel electrophoresis]]. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as [[DNA]] or [[protein]] in a gel; the rate at which it migrates varies according to gel density and [[buffer solution|buffer]] composition, but in a typical 1% [[agarose]] gel in [[TAE buffer]] or [[TBE buffer]], bromophenol blue migrates at the same rate as a DNA fragment of approximately 500 [[base pair]]s. [[Xylene cyanol]] and [[Orange G]] may also be used for this purpose.<ref name="Agarose gel electrophoresis (basic method)">{{cite web |url=http://www.methodbook.net/dna/agarogel.html |title=Agarose gel electrophoresis (basic method) |accessdate=2008-04-07 |format= |work=}}</ref>
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 [[dichromatism|dichromatic colour]].<ref name="pmid17534588">{{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}}</ref>
Bromophenol blue is commonly used in entry-level lab courses to stain proteins in wet-mount slides.<ref name="Protein gel electrophoresis">{{cite web |url=http://genetics.mgh.harvard.edu/szostakweb/protocols/protein_page/index.html |title=PROTEIN GEL ELECTROPHORESIS |accessdate=2008-04-07 |format= |work=}}</ref>
== References==
<references /></div>
[[Category:pH indicators]]
[[Category:Triarylmethane dyes]]
[[de:Bromphenolblau]]
[[fr:Bleu de bromophénol]]
[[it:Blu di bromofenolo]]
[[ja:ブロモフェノールブルー]]
[[pl:Błękit bromofenolowy]]
[[pt:Azul de bromofenol]]
[[vi:Bromophenol xanh]]