Murexide Test in Paper Chromatography

Abstract

MICHEL1 found that the purines on a moist filter paper, when treated with chlorine gas for 3 min., dried at 80–90° C. and left in an ammonia atmosphere for a few minutes form compounds which are detectable by their fluorescence in ultra-violet light. A true murexide test, with development of a pink coloration, can be carried out without using chlorine directly, by lightly spraying the paper first with a 10 per cent solution of chloramine T (B.P.) and then with N hydrochloric acid, followed by heating it in a steam-oven (96–98° C.) until there is no smell of chlorine. The dried paper is then passed slowly over the open mouth of a bottle of concentrated ammonia and heated in the steam-oven for 5–10 min., when the purines will show up as pink spots. It is sometimes necessary to repeat the ammonia treatment and subsequent heating to make the spot visible. Morgan2 used chloramine T as an oxidizing agent for detection of caffeine in the conventional way by the murexide test.