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bromothymol blue
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Bromothymol bule

Bromothymol bule

Bromothymol bule


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), such as managing the pH of pools and fish tanks. A common use is for measuring the presence of carbonic acid in a liquid. It is typically sold in solid form as the sodium salt of the acid indicator.

Grade:AR Grade

Purity(column chromatography-spectrophotometer):90% min

CAS Number :76-59-5

EC Number :200-971-2

Molecular Formula:C27H28Br2O5S

Technical Requirements:


Bromothymol bule

Appearance Purple or Pink Powder
PH Range  6.0 - 7.6, yellow to blue
Ignition Residue (w/%) 0.2% max
Absorption extinction/279-285 nm, methanol ≥9000
extinction/326-332 nm, methanol ≥8000


Bromothymol Blue (BTB) is a pH indicator (pKa approx. 7.1) that is used as a biological slide vital stain to define cell walls or nuclei under the microscope.
BTB is also a component of several bacterial growth and detection substrates such as cystine lactose electrolyte deficient (CLED/BROLACIN);
polymyxin pyruvate egg yolk mannitol bromothymol blue (PEMBA) and MacConkey agar.
Bromothymol blue may be used for observing photosynthetic activities, or as a respiratory indicator (turns yellow as CO2 is added).
It may also be used in the laboratory as a biological slide stain. At this point, it is already blue, and a few drops are used on a water slide. The cover slip is placed on top of the water droplet and the specimen in it, with the blue coloring mixed in.[clarification needed] It is sometimes used to define cell walls or nuclei under the microscope.
Bromothymol is used in obstetrics for detecting premature rupture of membranes. Amniotic fluid typically has a pH > 7.2, bromothymol will therefore turn blue when brought in contact with fluid leaking from the amnion. As vaginal pH normally is acidic, the blue color indicates the presence of amniotic fluid. The test may be false-positive in the presence of other alkaline substances such as blood or semen, or in the presence of bacterial vaginosis.

Packing:25g/bottle or according to your requirement.

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