QC Lesson 5

• Ash content


  The residue remaining after incineration which usually represents the amount of inorganic matter present as impurity
• Types of ash

  • Total ash
  • Acid-insoluble ash (silica residue)
  • Sulfated ash
• Moisture content


  The varying quantities of water/moisture contained in a drug
• Karl Fischer direct titration


  Based upon the quantitative reaction of water with an anhydrous solution of sulfur dioxide and iodine in the presence of a buffer
• Official methods for moisture content determination

  • Karl Fischer direct titration
  • Karl Fischer residual titration
  • Karl Fischer coulometric titration
  • Azeotropic/toluene distillation
  • Gravimetry (loss on drying)
• Extractive (soluble) content


  The filtered substance that passed through the filter paper
• Crude fiber (insoluble) content


  The residue that remains undissolved after successive treatment with boiling acid and alkali; mainly consists of cellulose
• Types of extractives

  • Alcohol-soluble extractive
  • Diluted alcohol-soluble extractive
  • Water-soluble extractive
  • Hexane-soluble extractive
• Constants of fats, oils, waxes, balsams and resins


  Physical and chemical properties or values that can determine the identity, purity and quality of a substance
• Methods for determining constants

  • Physical methods: Specific gravity, Melting point, Solidification point/congealing point
  • Chemical methods: Acid value, Saponification value, Ester value, Iodine value
• Saponification value


  Number of mg of KOH necessary to neutralize the free acid and to saponify esters contained in 1 g of substance
• Unsaponifiable matter


  Substances present in oils or fats that are not saponified by alkali hydroxides but soluble in ordinary fat solvent
• Iodine value


  Number of g of iodine absorbed under specified conditions by 100 g of a substance
• Volatile oils


  Odorous principles found in plants and animals
• Chemical components of volatile oils

  • Hydrocarbons
  • Alcohols
  • Aldehydes
  • Ketones
  • Phenols
  • Acids
  • Sulfur
• Physical methods for assaying volatile oils

  • Specific gravity
  • Refractive index
  • Optical rotation
• Specific gravity


  Ratio of the weight of oil to the weight of an equal volume of water at 25°C
• Instruments for determining specific gravity

  • Westphal balance
  • Pycnometer
  • Hydrometer
• 269(100)


  269 multiplied by 100
• Special Methods Used in Official Pharmaceutical Analyses
• Volatile Oil Content


  The content of volatile oils in a sample
• Volatile Oils


  Also known as Ethereal oils, essential oils, essences. Odorous principles found in plants and animals.

  • Chemical Components: – Hydrocarbons, Alcohols, Aldehydes, Ketones, Phenols, Acids, Sulfur
• Chemical Components of Volatile Oils

  • Hydrocarbons
  • Alcohols
  • Aldehydes
  • Ketones
  • Phenols
  • Acids
  • Sulfur
• Assay of Volatile Oils


  The analysis and quantification of volatile oils
• Physical Methods for Assaying Volatile Oils

  • Specific gravity
  • Solubility
  • Rotatory power
  • Refractive index
  • Congealing point
• Instruments for measuring specific gravity

  • Westphal Balance
  • Pycnometer
  • Hydrometer
• Classes of Volatile Oils Based on Specific Gravity

  • Oils Lighter than Water (sp gr <1.0)
  • Oils Heavier than Water (sp gr >1.0)
• Oils Lighter than Water

  Usually contains hydrocarbons, alcohols, esters and ketones. Examples: Orange, Caraway, Coriander, Lemon, Turpentine, Rosemary Oils
• Oils Heavier than Water

  Usually contains aldehydes, phenols and phenolic derivatives. Examples: Anise, Cinnamon, Clove and Sassafras Oils
• Solubility


  The solubility/miscibility of volatile oils is determined using organic solvents such as absolute alcohol, chloroform, ether, benzene, carbon disulfide
• Rotatory power


  Also known as optical activity. The ability of a substance to rotate plane polarized light either clockwise or counterclockwise
• Refractive index


  The ratio of the velocity of light in air to the velocity of light in the oil
• Congealing point


  The ability of an oil to solidify. Volatile oils with higher congealing point are more valued.
• Chemical Methods for Assaying Volatile Oils

  • Ester Content
  • Alcohol Content
  • Aldehyde and Ketone Content
  • Phenol Content
  • Volatile Oil in Crude Drugs and Oleoresins
  • Volatile Oil in Spirits
• Ester Content


  Most commonly found as acetates of alcohol. Detects any adulteration and to establish the quality of oils valued for their ester content. Determined by titration with HCl after treatment with alcoholic KOH.
• Alcohol Content


  Most commonly found as borneol and menthol. Assayed by acetylation method.
• Aldehyde and Ketone Content


  Makes use of "cassia flask". Methods of Assay: Bisulfite method, Hydroxylamine method (clove oil).
• Phenol Content


  Also makes use of "cassia flask". When shaken with NaOH solutions diminish in volume as phenol is readily soluble in NaOH.
• Volatile Oil in Crude Drugs and Oleoresins


  Done by steam distillation. Makes use of "clavenger apparatus".
• Volatile Oil in Spirits


  Determined by treatment with an immiscible solvent. Makes use of "babcock bottle".