IV. ANALYTICAL TECHNIQUES

1. Separations and Extractions

SEPARATIONS

  1. List some of the factors to consider when trying to separate a particular compound from a mixture.
  2. What is a "basic" drug?
  3. To what do the terms “cocaine base,” “crack,” "freebase" and “rock” refer to?
  4. List three different general extraction schemes used to separate different classes of drugs.
  5. List three different literature resources when trying to determine solubility of different chemical species.
  6. What is pKa? How does it relate to pH?
  7. What is the general scheme for basic extractions? List some reagents that can be used for such extractions.
  8. What is the general scheme for acidic extractions? List some reagents that can be used for such extractions
  9. What is an "amphoteric" extraction? Why is it more difficult to perform than an acidic or basic extraction?
  10. Some drugs do not have an acid/base or salt form. Explain why these drugs can be extracted using a basic/acidic scheme.
  11. List the general steps when using solid phase extraction (SPE) in drug analysis.
  12. What is a preparative column? What is it used for?
  13. List the general steps for the use of a silica chromatographic column. What situations would require its use? Why are these types of chromatographic columns not routinely used?

EXTRACTION TECHNIQUES

  1. Name an organic solvent generally suitable for the separation of the free base from a salt form for a controlled substance.
  2. Describe the term “solubility”.
  3. Define the following terms: very soluble, freely soluble, soluble, sparingly soluble, slightly soluble, very slightly soluble and practically insoluble.
  4. Describe the term “dry extraction”.
  5. Devise a dry extraction scheme to separate a mixture of cocaine base, cocaine hydrochloride and inositol. Illustrate the separation by a diagram.
  6. Describe the term “liquid-liquid extraction”.
  7. Devise a liquid-liquid extraction scheme to separate a mixture of methamphetamine and phenobarbital. Illustrate the separation by a diagram.
  8. Describe the difference between simple and fractional recrystallization?
  9. The pKa of methamphetamine is 10. When performing an acid-base extraction of methamphetamine using water and hexane, what pH should you adjust the aqueous layer to so that all of the methamphetamine extracts into hexane?
  10. A sample contains the following: 10% procaine HCl, 15% quinine HCl, 15% methapyraline HCl, 7% heroin HCl, 3% heroin base, and 50% lactose. How do you isolate the heroin base?

Last Update June 2018

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