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Description
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Colourless, hexagonal or needle-like crystals, or infused masses or a crystalline powder; has a pleasant peppermint-like odour
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Solubility
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Very soluble in ethanol (95%) and in ether; freely soluble in light liquid paraffin, in glacial acetic acid and in volatile oils, slightly soluble in water
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Identification
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-
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Identification 'A'
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The spectrum of sample should be concordant with spectrum of standard
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Identification 'B'
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The colour should changes to violet (Distinction from thymol)
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Identification 'C'
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The principal peak in the chromatogram obtained with the test solution corresponds to the peak in the chromatogram obtained with the reference solution
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Appearance of solution
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The solution is not more opalescent than opalescence standard OS4, and not more intensely coloured than reference solution RS6
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Acidity
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The solution should be yellow
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Specific optical rotation
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For (-)-menthol -49.0° to -51.0°,For (± )-menthol -2.0 °to +2.0°
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Congealing range of (± )menthol
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27.0° to 28.0°
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Melting range of (-)-menthol
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41.0° to 44.0°
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Related Substances
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-
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Isomethanol
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NMT 0.5%
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Single maximum impurity
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NMT 0.3%
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Total impurities
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NMT 2.0%
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Readily oxidisable substances in (+) menthol
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The purple colour of potassium permanganate should be apparent after 5 minutes
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Residue on evaporation
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NMT 0.05%
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Assay
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NLT 98.0% and NMT 102.0%
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