Paracelsus Medical University Salzburg
Question
Asked 6th Jun, 2015
What is the original color of bromothymol blue (BTB)?
BTB reagent as pH indicator in my laboratory is red to yellow, while the pH color range for BTB is yellow, green, to bluish (acid to base). So, what's the original color of BTB? Because I suspected the one in my laboratory has expired.
Thank you.
All Answers (3)
Dear Nur Shabrina,
not really an expert with this (assuming from the text that you ask about the "natural color of the dye powder" you are in possession for your experiment?) I only have a German source and a company website (from China)(http://www.moneidechem.com/product/prodetail-49038.html) that the natural dye stuff is kind of <pink>/<peachblow> / Appearance: Pale pinkish purple or red crystalline powder.
Sources/References:
I also would like to cite & provide a pdf (attached) containing specific info from
© Conn's Biological Stains, A Handbook of Dyes, Stains and Fluorochromes for use in Biology and Medicine (HOROBIN RW & KIERNAN JA, eds) 10th Ed. © BIOS Science. Publ. (Oxford,UK) 2002 and other sources.
Best wishes and regards,
Wolfgang
South Valley University
Dear Nur Shabrina,
I worked a little bit with BTB in the lab. BTB has three colours according to pH (yellow, blue green and deep blue) in acidic, neutral and basic respectively. so you can just prepare three solutions with three pH like 4, 7 and 9 and you can test your BTB if it givess the same coloures as I mentioned before I think it will ok and you can use it, but, if it doesn't, you have to change it
Best regards
Mahmoud
King Abdulaziz University
BTB is a weak acid and it is almost red in color. However, when it reacts with acidic solution then it turns into yellow color and blue color after reacting with alkaline solution. At neutral pH (7.0) it shows bluish green color. You can find the witness at the attached image of different solutions.
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