Question

What is the pH range of Bromophenol blue?

(a) 3.0 – 4.6

(b) 8.0 – 10.0

(c) 5 – 8

(d) 6.4 – 8.0

I had been asked this question in a job interview.

My doubt is from Isolation and Screening of Industrially Important Microbes topic in division The Isolation, Preservation and Improvement of Industrial Microorganisms of Fermentation Technology

Answer 1

Correct choice is (a) 3.0 – 4.6

Easy explanation: The pH range of Bromophenol blue is 3.0 – 4.6. It changes from yellow at pH 3.0 to blue-violet at pH 4.6. It works best in this range and is also used as a tracking dye in Agarose-Gel Electrophoresis.