home
site map appendix about course read first lab manual
read first
site map read first about course lab manual appendix

Lab I

Lab II

Lab III

Lab IV

Lab V

Lab VI

Lab VII

Lab VIII

Lab IX

Lab X

Lab XI

Lab XII

 

Lab I: TLC Analysis of Analgesic Drugs

Pre-lab Work

Reading Assignment:

  1. Safety, Laboratory Glassware, & The Laboratory Notebook:
    'Read First' Section & Mohrig
    --Techniques 1-3, pp. 1-33 2nd edition or pp. 1-28 3rd edition.
  2. Thin-Layer Chromatography
    Mohrig, 2nd edition, Technique 15, pp.177-189 or 3rd edition, Techniques 17, pp. 221-235 and Appendix

Pre-lab Questions:
(Please turn in the answers to these questions when you arrive to your first lab.)

  1. Have you taken the Safety Quiz on the "CHEM-Safety Quiz" Sakai site? (If not, please do so before our 2nd lab.)
  2. What are the TWO pieces of personal protective equipment that you will where during all of our labs?
  3. How many TLC plates will you develop and how many lanes will each of your TLC plates have on it?
  4. What's the purpose of the UV lamp in this lab?
  5. Where will you dispose of your TLC plates and any eluting solvent when finished with your lab?


Experimental Work

Objectives:

  • To resolve mixtures of unknown commercial painkillers using TLC.
  • To identify the individual components of each unknown mixture and to identify the unknown commercial painkillers.

Safety Notes

Ethyl acetate, ethanol, and glacial acetic acid are flammable and volatile. Solvents must be used in the hoods and TLC plates should be prepared and developed in the hoods.

Silica gel plates must not be thrown in the trash. Give them to your lab instructor when you have finished with them.

UV light is harmful to your eyes. Do not look at the UV lamps and do not aim them at your neighbors.


Experimental Procedure
Obtain a lab coat from your instructor and write your name on it. Take note from your Instructor on where you will be storing your lab coat for the course.

Perform the procedure for Thin Layer Chromatography as described in the Appendix.

Table 1: Commercial painkillers and their components

Printable Table1

 

Components of Commercial Painkillers (Standards)

Acetaminophen

Aspirin

Caffeine

Ibuprofen

Anacin

 

X

X

 

Bufferin

 

X

 

 

Excedrin (extra-strength)

X

X

X

 

Tylenol

X

 

 

 

Motrin

 

 

 

X

Molecular Structure

of

the compounds

 

 

 

 

Waste disposal and Clean-up

  1. Dispose of used microcapillary tubes in the glass disposal box.
  2. Discard used TLC plates in the silical gel solid waste container in the Waste Hood.
  3. The used filter paper wick should be allowed to dry in the hood, and disposed of with other solid waste.
  4. Dispose of excess eluting solvent in the flammables (acetone) waste container.
  5. Rinse your developing chamber with acetone from a wash bottle. Dispose of the acetone wash in the waste bottle and return the beaker to the appropriate tote.


Post-lab Questions:

(Please turn in the answers to these questions when you arrive at your NEXT lab.)

  1. Draw the structures for each of the three analgesics and caffeine, using ChemDraw. (Complete Table 1)
  2. What were the unknown commercial painkillers and what are the individual components in each?
  3. Explain how you used all of your lab data (Rf values, iodine stains, and appearence under UV) to help you identify your unknown analgesics.
  4. Using ONLY the information of how the individual components of the painkillers were separated on the TLC plate, what do you know about the various compounds and how they differ in polarity from the most polar compound to the least polar compound?
  5. Discuss any unexpected results in your experiment and state what you would do differently to improve your results.