สารบัญ

Thai name  น้ำมันโกฐจุฬารส (NAMMAN KOT CHULA ROT)

Category  Counter-irritant; expectorant; pharmaceutic aid.

        Eucalyptus Oil is obtained by steam distillation and rectification from the fresh leaves or the fresh terminal branchlets of various species of Eucalyptus globulus Labill., E. polybractea R.T. Baker, and E. smithii R.T. Baker (Family Myrtaceae).  It contains not less than
70.0 per cent w/w and not more than 95.0 per cent w/w of cineole, C₁₀H₁₈O.

Origin of plant  Eucalyptus Oil-yielding plant is native to Australia.

Constituents  Eucalyptus Oil contains cineole (eucalyptol), camphene, p-cymene, -pinene, -terpineol, γ-terpinene, camphene, etc.

Description  Odour aromatic, reminiscent of eucalyptus leaves; taste, pungent, camphoraceous, followed by a cold sensation.

Other relevant information  Eucalyptus oil  should not be administered internally to children or patients with gastro-intestinal tract inflammation, gall bladder disease, or impaired liver function.

Packaging and storage  Eucalyptus Oil shall be kept in well-filled, tightly closed containers, protected from light, and stored at a temperature not exceeding 25°.

Identification  Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
     Standard solution  Dissolve 20 µL of a-terpineol and 50 µL of cineole in toluene and dilute to 5 mL with toluene.
     Test solution  Dissolve 100 mg of the sample in toluene and dilute to 10 mL with the same solvent.
     Adsorbent  Silica gel G (TLC or HPTLC plate).
     Mobile phase  Ethyl acetate and toluene (10:90).
     Application  Apply 10 µL (or 2 µL) each of Standard solution and Test solution as 10-mm (or 6-mm) bands.
     Development and drying  Allow the solvent front to ascend 15 cm (or 6 cm) above the line of application.  Dry the developed plate in air.
     Detection  Spray the plate with anisaldehyde TS, heat at 100° for 5 minutes, and examine in daylight.
     Results  When examined in daylight, the test solution shows an intense violet brown band due to 1,8-cineole in the middle of the chromatogram, corresponding in colour and R_f to the bands shown by the standard solution.

Solubility test  Soluble, at 20°, in 5 volumes of ethanol (70 per cent).

Relative density  0.906 to 0.927 (Appendix 4.9).

Refractive index  1.458 to 1.470, at 20° (Appendix 4.7).

Optical rotation  0° to +10° (Appendix 4.8).

Assay  Carry out the determination as described in the “Gas Chromatography” (Appendix 3.4).
     Internal standard preparation  Dissolve 1 volume of anisole in 250 volumes of hexane.
     Standard preparation  Weigh accurately about 100 mg of Cineole RS and dissolve in 25.0 mL of hexane.  Pipette 5.0 mL of this solution, add 5.0 mL of Internal standard preparation and add hexane to 100.0 mL.
     Assay preparation  Weigh accurately about 100 mg of Eucalyptus Oil and dissolve in 25.0 mL of hexane. Pipette 5.0 mL of this solution, add 5.0 mL of Internal standard preparation and add hexane to 100.0 mL.
     System suitability preparation  Dissolve sufficient quantities of cineole and limonene in hexane to obtain a solution containing about 200 µg per mL each.
    Chromatographic system
          DETECTOR  Flame ionization.
          COLUMN  A glass column (5 m × 3 mm), packed with a 10 per cent w/w of alkylene glycol phthalate ester on silanized diatomaceous support (150 to 180 µm).
          TEMPERATURE
                Column 120°  
                Injection port 120°
                Detector 120°
          CARRIER GAS  Nitrogen.
          FLOW RATE  Adjust so that the retention time of cineole is about 11 minutes.
    System suitability
           Sample  System suitability preparation and Standard preparation.
     Suitability requirements
          RESOLUTION Not less than 1.5 between cineole and limonene peaks.
          RELATIVE STANDARD DEVIATION  The relative standard deviation is not more than 2.0 per cent for the cineole peak.  
     Procedure  Separately inject equal volumes (about
2 µL) of Standard preparation and Assay preparation into the chromatograph, record the chromatograms, and measure the areas of cineole and anisole peaks.  Calculate the area ratios of cineole to anisole peaks.
     Calculation Calculate the content of C₁₀H₁₈O in the portion of Eucalyptus Oil taken, using the declared content of C₁₀H₁₈O in Cineole RS.