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From left to right solutions of 0.1 M HCl, 3 buffer solutions of pH 3.78, 3 of pH 4.00, 3 of pH 4.62 and NaOH 0.1 M after adding different amounts of bromocresol green (more in darker solutions) In aqueous solution , bromocresol green will ionize to give the monoanionic form (yellow), that further deprotonates at higher pH to give the dianionic ...
Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a dye of the triphenylmethane family (triarylmethane dyes) and a pH indicator. It is colored yellow below pH 5.2, and violet above pH 6.8. In its cyclic sulfonate ester form, it has a pK a value of 6.3, and is usually prepared as a 0.04% aqueous solution. [1]
DTM plate on the right showing color change after two days' growth; Microsporum canis Dermatophyte test medium (DTM) is a specialized agar used in medical mycology. [1] [2] It is based on Sabouraud's dextrose agar with added cycloheximide to inhibit saprotrophic growth, antibiotic to inhibit bacterial growth, and phenol red a pH indicator.
As CO 2 is absorbed from the breath into the solution, carbonic acid forms and change the solution color from green to yellow. Thus, BTB is commonly used in science classes to demonstrate that the more that muscles are used, the greater the CO 2 output.
Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered ...
This is sometimes called green hemolysis because of the color change in the agar. Other synonymous terms are incomplete hemolysis and partial hemolysis . Alpha-hemolysis is caused by the bacteria's production of hydrogen peroxide , which oxidizes hemoglobin and produces the green oxidized derivative methemoglobin .
Agar plates may also be indicator plates, in which the organisms are not selected based on growth, but are instead distinguished by a color change in some colonies, typically caused by the action of an enzyme on some compound added to the medium. [6] The plates are incubated for 12 hours up to several days, depending on the test that is performed.
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.