Bromothymol Blue

Product : Bromothymol Blue
C.A.S. No. :76-59-5
M.F. : C27H28Br2O5S
M.W. : 624.40gm/mole

Specifications:

Dye Content (by Spectrophotometry) >95%
Transition Range pH 5.8-7.6
Yellow-Blue
Solubility 0.1% (95% EtOH) Clear solution
Absorption maximum (pH 5.8) 1max 430-435nm
Absorption maximum (pH 7.6) 2max 615-618nm
Absorptivity (A1%/1cm at pH 5.8 at 1max) 260-300
Absorptivity (A1%/1cm at pH 7.6 at 2max) 470-520
Loss On Drying (110C) <3%

Product Description:

Bromothymol blue is a large compound with a molecular weight of 625 g/mol. It contains three aromatic benzene rings. The first benzene ring has a thym group attached (the 'thym' part of the name), a sulfur with two oxygen atoms double bonded to it, and another oxygen single bonded to it. The second and third benzene rings each have a bromine (the 'bromo' part of the name), alcohol (the 'ol' suffix), a tert-butyl group, and a methyl group. This 0.1% aqueous bromothymol blue solution (also known as Bromthymol Blue) is a commonly used pH indicator. Bromthymol blue changes color over a pH range from 6.0 (yellow) to 7.6 (blue). It is a good indicator of dissolved carbon dioxide (CO2) and other weakly acidic solutions. Despite its name, bromothymol blue solution may sometimes appear yellow or reddish depending on the pH of the stock water used to prepare this pH indicator solution. Low levels of carbon dioxide or acid in solution with bromothymol blue indicator will appear blue. As the level of carbon dioxide or acid increases, the solution will gradually take on a yellow tint. This makes bromothymol blue ideal for biology experiments to indicate photosynthetic activity (solution turns blue as plants use up carbon dioxide) or respiratory activity (solution turns yellow as carbon dioxide content increases).