Finals Exam

• Ash


  The inorganic residue remaining after the water and organic matter have been removed by heating in the presence of oxidizing agents, which provides a measure of the total amount of minerals within a food
• Analytical techniques for determining ash content


  • Based on the fact that minerals can be distinguished from other food components in some measurable way
  • Minerals are not destroyed by heating and have low volatility compared to other food components
• Main types of analytical procedures to determine ash content


  • Dry ashing
  • Wet ashing
  • Low temperature plasma dry ashing
• Inorganic matter


  Chemical compounds that contain no carbon (C)
• Modus operandi


  A particular way or method of doing something, especially one that is characteristic or well-established
• Acid-insoluble ash


  The part of total ash which is insoluble in diluted hydrochloric acid
• Purposes of determining official ash values


  • To detect and check adulteration with exhausted drugs
  • To detect and check absence of other parts of the plant
  • To detect and check adulteration with material containing either starch or stone cells
  • To ensure the absence of an abnormal proportion of extraneous mineral matter
• Residue on ignition


  Ignition to dull redness to determine the ash content of chemicals
• Negligible


  A quantity not exceeding 500 mcg
• Loss on ignition


  Provides a means of determining the percentage of test material which is volatilized and driven off under the specified conditions
• Methods for determining water content


  • Gravimetric (for drugs containing no constituents volatile at 105°C)
  • Gravimetric (for drugs containing ether-soluble constituents volatile at 105°C)
  • Azeotropic method (USP) or moisture method by toluene distillation (NF)
  • Titrimetric (Karl Fischer)
  • Dew point
  • Electrolytic hygrometric

  
• The careful control of temperature is the most important analytical factor to regulate in making ash determinations
• Temperature equivalents in an electric furnace


  • Very dull-red heat = 500-550°C
  • Dull-red heat = 550-700°C
  • Bright-red heat = 800-1000°C
  • Yellow-red heat = 1000-1200°C
  • White heat = 1200-1600°C
• Substances with ash limits
• Substances with acid-insoluble ash limits
• The importance of determining ash content is to detect and check adulteration, absence of other plant parts, and the presence of extraneous mineral matter
• The significance of determining water content is to provide a means of quantifying the volatile components in a sample
• Volatile oils are the odorous principles found in various plant parts
• Volatile oils


  Also called ethereal oils or essential oils, they represent the "essences" or the odorous constituents of plants
• Components of volatile oils


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


  The ratio of the density of a substance to the density of a standard, usually water for a liquid or solid, and air for a gas
• Adulteration


  The action of making something poorer in quality by the addition of another substance
• Extraneous


  Irrelevant or unrelated to the subject being dealt with
• Methods of general application for volatile oil analysis


  • Specific gravity
  • Rotary power
  • Refractive index
  • Congealing temperature
  • Distillation range
  • Fractional distillation
  • Solubility
• Assay for ester content


  1. Esters + alc. KOH (saponification) → free alcohol and potassium salt

  2. Ester value must be determined
• Assay for alcohol content

  Free alcohols + acetic anhydride (boil) → acetates
• Fractional Distillation


  • Separation of various components
  • Detection of adulteration

  
• Solubility


  Soluble in organic solvents: absolute alcohol, ether, chloroform, benzene, carbon disulfide
• Assay for Ester Content


  • Mostly the acetates of alcoholic volatile oils such as borneol, geraniol, menthol or citronellol
  • Esters + alc. KOH (saponification) → free alcohol and potassium salt
  • Ester value must be determined
  • Serves to detect adulteration and to establish the quality of oils valued for their ester content
• Assay for Alcohol Content


  • Reagent: acetic anhydride/anhydrous sodium acetate
  • Free alcohols + acetic anhydride (boil) → acetates
  • Using acetylization flask
• Assay for Aldehyde Content


  • Bisulfite method: Addition of 5% sodium bisulfite sol. → product dissolves in water → nonaldehyde content as water-insoluble layer
  • Hydroxylamine method: Titration process, addition of hydroxylamine HCl sol.
• Assay for Ketone Content


  • Only caraway oil and spearmint oil
  • Same with Assay for Aldehyde Content
  • Ketone content dissolves in the aqueous layer
• Assay for Phenol Content


  • Phenols + NaOH → decrease in volume
  • Phenol constituents are readily soluble in alkali
• Volatile oils are important to check and maintain quality
• General application of volatile oils


  • Not provided
• Determining aldehyde content


  1. Bisulfite method: Addition of 5% sodium bisulfite sol. → product dissolves in water → nonaldehyde content as water-insoluble layer

  2. Hydroxylamine method: Titration process, addition of hydroxylamine HCl sol.
• Determining phenol content


  1. Phenols + NaOH → decrease in volume

  2. Phenol constituents are readily soluble in alkali