Finals

• Gravimetric analysis


  The measurement of the weight of a substance in a sample
• Laws and theories of chemistry in gravimetric analysis


  • Law of Mass Action
  • Reversible Reactions
  • Solubility product principle
  • Common ion Effect
• Gravimetric methods


  • Measurement of the weight of a substance in a sample
  • Calculation of the weight of a substance in a sample from the weight of a chemically equivalent amount of some other substance
• Methods of separation


  • Physical methods
  • Chemical methods
• Physical methods


  • The substance to be measured gravimetrically is separated from other substances composing the sample by physical methods, purify and weigh without chemical change
  • Frequently used in pharmaceutical analysis
• Physical method example


  • The quantity of amobarbital in amobarbital tablets determined by extraction, purifying further by complete removal of solvent, and weight the amobarbital in a sample of the powdered tablets
• Chemical methods


  • Employed when other components of the sample are such that separation by physical means of the substance being measured is not possible or not convenient
  • Convert the substance to a chemically equivalent amount of some other substance which can be separated, purified and weighed
  • Using the known weight relationship between the substance being measured and the substance ultimately weighed
• Chemical method examples


  • The component of the sample being assayed may be precipitated from solution
  • It may be a decomposition product resulting from ignition of a compound
  • It may be deposited on an electrode by electrolysis
• Gravimetric factor (AKA: Chemical factor)


  The molecular weight of the sample proportionate to the molecular weight of residue/precipitate obtained from it
• Special methods of analysis

  • Chemical methods
  • Biological methods
• Chemical methods


  • Ash content
  • Moisture content
  • Crude fiber
  • Extractive
  • Alkaloidal content
• Biological methods


  • Microorganisms
  • Animal/Animal tissues
  • Use specific devices
  • Assays of Digoxin, insulin, heparin
  • Safety
• Ash content


  The residue remaining after incineration, representing naturally occurring and adhering inorganic salts, as well as inorganic matter from adulteration
• The ash or residue yielded by an organic chemical compound is as a rule a measure of the amount of inorganic matter present as impurity
• Approximate temperature equivalents


  • Very dull red heat (500-550°C)
  • Dull red heat (550-700°C)
  • Yellow-Red Heat (800-1000°C)
  • Bright Red Heat (1000-1200°C)
  • White Heat (1200-1600°C)
• Ash standards


  • Total ash
  • Acid-insoluble ash
  • Water soluble ash
• Residue of ignition (AKA: Sulfated ash)


  Used to determine the content of inorganic impurities in an organic substance, by measuring the amount of residual substance not volatilized from a sample when the sample is ignited in the presence of sulfuric acid
• Loss on drying


  Provides means of determining the percentage of test material which is volatilized and driven off, without being destructive to the substance under test
• Methods for water content determination

  • Method I (Titrimetric, Karl Fischer)
  • Method II (Azeotropic Toluene Distillation)
  • Method III (Gravimetric)
• Karl Fischer method


  Most rapid of the official methods, requires only a small sample, specific only for water, widely applicable in determination of the water content of drug products
• Karl Fischer components


  • Iodine, Sulfur dioxide, Pyridine, Anhydrous methanol
• Extractive


  The amount of extractive a drug yields to a given solvent is often an approximate measure of the amount of a certain constituent or group of related constituents the drug contains
• Solvents used for extractives

  • Ether
  • Alcohol
  • Water
  • Hexane
• Crude fiber


  The residue, consisting chiefly of cellulose, that remains undissolved after successive treatment with boiling acid and alkali
• Crude fiber content is important in the examination of species, as commonly used adulterants consist of waste material or refuse material derived from the drugs or spices themselves or from other food products
• Constants of fats, fatty oils, waxes, balsams and resins


  Physical and chemical properties used to determine purity and quality, in conjunction with odor, identity tests, color and taste
• Acid value (AKA: Acid #, Acidity index)


  Measure of the acidity of fats and fixed oils
• Extracted constituents


  • Ether
  • Alcohol
  • Water
  • Hexane
• Crude fiber


  The residue, consisting chiefly of cellulose that remains undissolved after successive treatment with boiling acid and alkali
• Crude fiber


  • Important in the examination of: species - commonly used adulterant consist of waste material or refuse material derived from the drugs or spices themselves of from other food products
• Methods of analysis


  1. Determination of a number of physical and chemical properties

  2. Odor

  3. Special identity test

  4. Color

  5. Taste
• Acid value


  The number of milligrams of potassium hydroxide necessary to neutralize the free acids in 1g of oil, fat, wax, resin balsam or similar organic substance of complex composition
• Ester value


  The number of milligrams of potassium hydroxide required to saponify the esters in 1 g of a fatty or volatile oil, fat, wax, balsam, resin or similar substance
• Saponification value


  The number of milligrams of potassium hydroxide required to neutralize the free acids and saponify the esters contained in 1g of fat, fatty or volatile oil, wax, resin, balsam or other substance of similar composition
• Unsaponifiable matter


  The substances present in oils or fats that are not saponified by addition of alkali hydroxides but are soluble in ordinary fat solvents
• Iodine value


  The number of grams of iodine absorbed under specified conditions by 100g of oil, fat, wax or other substances
• Hydroxyl value


  The number of milligrams of potassium hydroxide equivalent to the hydroxyl content of 1g of the substance
• Acetyl value


  The number of milligrams of potassium hydroxide required to neutralize the acetic acid obtained by the saponification of 1g of acetylated fatty acids
• Important components of official volatile oils

  • Sulfur compounds
  • Aldehydes
  • Hydrocarbons
  • Phenols
  • Alcohols
  • Acids
  • Ketones
• Specific gravity


  Ratio of the weight of the volume of volatile oil to that of an equal volume of pure water when both are determined at 25°C