- Quinine in solution in dilute sulphuric, acetic, phosphoric or tartaric acids exhibits a strong blue fluorescence which is very marked in extremely dilute solutions. The hydrochloride and other halogen compounds do not give fluorescence in solution.
- Thalleioquin test: Dissolve a small amount of quinine in dilute sulphuric acid and add 1–2 ml of water. Add 2 to 3 drops of bromine water and shake the mixture. On the addition of a drop of strong ammonia an emerald green colour is produced.
- A small quantity of quinine when slightly moistened with glacial acetic acid and heated in an ignition tube shows condensation of blood-red drops on the sides of the tube.
- Erythroquinine test: To a solution of quinine in dilute acetic acid, add 1 to 2 drops of bromine water followed by a drop of 10% solution of potassium ferricyanide. On adding a drop of strong ammonia the solution turns red.
- TLC identification: Apply 5 µl of 1% solution of quinine in methanol on a silica gel G plate along with a similar sample of quinine sulphate reference sample. Develop in a solvent system made up of 40 volumes of toluene, 24 volumes of ether and 10 volumes of diethylamine. Dry the plate at 105°C for 30 min, allow to cool and spray with potassium iodoplatinate solution (50 ml of 5% w/v solution of chloroplatinic acid and 45 ml potassium iodide solution (20%) made up to 100 ml with water). Violet brown-coloured spot, a standard for the test sample well comparable with that of reference sample, is obtained.
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