Dische test

The Dische test, or Dische reaction, is used to distinguish DNA from RNA. It was invented by Zacharias Dische.

Method
Dische's diphenylamine reagent consists of diphenylamine, glacial acetic acid, sulfuric acid, and ethanol.

When heated with DNA, it turns blue in the presence of DNA. A more intense blue color indicates a greater concentration of DNA.

Mechanism
The acid converts deoxyribose to a molecule that binds with diphenylamine to form a blue substance. The reagent does not interact with RNA, so can be used to distinguish DNA from RNA.