MUSCAT CHEMICAL TAG::
Dragendorff's reagent is a color reagent to detect alkaloids in a test sample or as a stain for chromatography plates.DR is a solution of potassium bismuth iodide composing of basic bismuth nitrate (Bi(NO₃)₃), tartaric acid, and potassium iodide (KI), and when contact with alkaloids DR produces an orange or orange red precipitate.
Dragendorff's reagent is prepared by mixing a concentrated solution of potassium iodide with a solution of bismuth subnitrate in a diluted acid as a low pH is mandatory for this reagent.
The Dragendorff reagent has two solutions. One is bismuth nitrate in acetic acid. This is followed by a sodium nitrate solution. Alkaloids are indicated by a reddish-brown deposit.