Jaffa sample

Jaffa sample (M. Jaffe). 1. Test for detection of indican. To the investigated liquid, released from the protein, add an equal amount of concentrated hydrochloric acid, 1-2 ml of chloroform and a few drops of saturated solution of bleach. The tube is closed and its contents carefully mix for 1-2 minutes In the presence of indican the bottom of the chloroform layer is colored in blue. Reaction caused by hydrolytic cleavage of indican in the presence of concentrated hydrochloric acid on indoxyl and acid sulphate potassium, oxidation indoxyl in blue Indigo and the dissolution of the latter in chloroform.
2. Test for detection of creatinine. To 1-2 ml of the investigated liquid (usually urine) add 5-6 drops of 10% solution of caustic soda and 3-4 drops of saturated solution of picric acid. Orange-red color is associated with the formation of tautomer of picrate creatinine.