Diphenylamine test

Monica: Don’t we use the diphenylamine test, Dr. Brown?

Dr. Brown: You are right, Monica that this test indicates the presence of one of the biomolecules, but not protein.

You: DNA can be specifically detected using the Dische diphenylamine reagent. The deoxyribose moiety of DNA is converted to a molecule that binds with diphenylamine to form a blue color, which is proportional to the concentration of DNA. The diphenylamine test is thus a quantitative test for DNA. Here, I can show you the image I took when we carried out this lab in class.

[Experimental procedure: Obtain three test tubes and add 0.1-2 ml of DNA solution to #1 and to #2, and add 0.1-2 ml of water to #3. Then add 2 ml diphenylamine reagent to each, place in a boiling water bath for ten minutes. Observe for a light blue color forming.]

Website: https://socratic.org/questions/how-can-you-easily-identify-nucleic-acids

Dr. Brown: Well-done! So, let’s re-think the right test to detect protein. You remember a useful video as well and decide to watch it and help you visualize this test.