สารบัญ

        Gentian                                       1 part      
        Ethanol (70 Per Cent)                   5 parts     
        Prepare by a suitable procedure (Appendix 7.18).

Description  Yellowish brown or reddish brown liquid; taste, bitter.

Identification  Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
     Standard solution  Dissolve 5 mg of hyperoside, and 5 mg of phenazone in 10 mL of methanol.
     Test solution  Use Gentian Tincture.
     Adsorbent  Silica gel F254.
     Mobile phase  Water, anhydrous formic acid and ethyl formate (4:8:88).
     Application  Apply 20 µL each of Standard solution and the tincture as 10-mm bands.
     Development and drying  Allow the solvent front to ascend 8 cm above the line of application in an unsaturated tank.  Dry the developed plate in air.
     Detection A  Examine the plate under ultraviolet light (254 nm).
     Results A  When examined under ultraviolet light (254 nm), the test solution shows a prominent quenching band due to gentiopicroside in the lower third of the chromatogram, corresponding in R_f to the quenching band of hyperoside shown by the standard solution.  There is also a weak quenching band due to amarogentin in the middle and a prominent quenching band in the upper third of the chromatogram.
A quenching band of phenazone obtained from the standard solution appears also in the upper third with R_f value between that of amarogentin and of the prominent quenching band from the test solution
     Detection B   Spray the plate with a 10 per cent w/v solution of potassium hydroxide in methanol and then spray with a freshly prepared 0.2 per cent w/v solution of fast blue B salt in a mixture of equal volumes of anhydrous ethanol and water.  Examine the plate under visible light.
     Results B   When examined under visible light, the test solution shows a weak light brown band due to gentiopicroside in the lower third of the chromatogram, corresponding in R_f to the brownish red band due to hyperoside shown by the standard solution.  A violet-red band due to amarogentin and a dark violet band of higher R_f value in the upper third of the chromatogram are present.

Ethanol content  62 to 67 per cent v/v (Method II, Appendix 6.5).

Dry residue  Not more than 5 per cent w/w.  Introduce rapidly 3.0 g of the Gentian Tincture in a flat-bottomed dish, about 50 mm in diameter and about 360 mm deep.  Evaporate to dryness on a water-bath and dry at 105° for 3 hours.  Allow to cool in a desiccator over self-indicating silica gel and weigh.

Other requirements  Complies with the requirements described under “Tinctures” (Appendix 1.16).