How can you easily identify nucleic acids?

1 Answer
Feb 7, 2018

By using the Dishe's diphenylamine test...

Explanation:

Diphenylamine is used to test for nitrates:

https://en.wikipedia.org/wiki/Diphenylamine

However, it can also react with the Deoxyribose sugar component of DNA:

When a sample is boiled with a strong acid, the resulting depurination of any DNA present, and the subsequent dehydration of the 2D-Deoxyribose sugar produces highly reactive ω-hydroxylevulinylaldehyde . (This reaction is not specific for DNA, but for 2-Deoxypentoses.)

In an acidic solution, the ω-hydroxylevulinylaldehyde reacts with diphenylamine to produce a blue-coloured complex that absorbs at 595 nm.

Reaction mechanism:

http://nptel.ac.in/courses/102103047/6#

Result:
https://sites.google.com/a/wrps.net/cns-ontl/cns-2nd-semester-weblinks/unit-7-resources---lab/chemical-tests-to-identify-biomolecules

If RNA is present, the result will turn Green...