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Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid.
Hence, a pH indicator is a chemical detector for hydronium ions (H 3 O +) ... Bromothymol blue: yellow 6.0 7.6 blue Phenol red: yellow 6.4 8.0 red Neutral red: red 6.8
A universal indicator is usually composed of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue. [5] The colours that indicate the pH of a solution, after adding a universal indicator, are:
Bromophenol is also used as a colour 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 as DNA or protein in a gel; the rate at which it migrates varies according to gel density and buffer composition, but in a typical 1% agarose gel in ...
Phenolphthalein's common use is as an indicator in acid-base titrations. It also serves as a component of universal indicator, together with methyl red, bromothymol blue, and thymol blue. [3] Phenolphthalein adopts different forms in aqueous solution depending on the pH of the solution.
Bacteria are inoculated on a medium containing sodium citrate and a pH indicator such as bromothymol blue. The medium also contains inorganic ammonium salts, which are utilized as sole source of nitrogen. Use of citrate involves the enzyme citrate lyase, which breaks down citrate to oxaloacetate and acetate.
The increase in pH then causes color change in the bromothymol blue indicator, turning it blue. Under neutral conditions the medium remains a green color. The color change to blue is useful because growth on Simmons' citrate agar is often limited and would be hard to observe if it were not for the color change.
The agar contains citrate and ammonium ions (nitrogen source) and bromothymol blue (BTB) as a pH indicator. [2] Bromothymol blue was added in order to reduce false positives. The citrate agar is green before inoculation, and turns blue, because of BTB as a positive test indicator, meaning citrate is utilized.
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