TLC Analysis of Analgesic Drugs
Introduction:
The purpose of this lab was to determine the composition of four different over-the-counter drugs (Anacin, Bufferin, Excedrin, and Tylenol). These compositions were determined by using the method of thin-layer chromatography (TLC) of the four over-the-counter drugs, which were then compared to four different components of drugs (acetaminophen, aspirin, caffeine, and salicylamide).
Experiment Scheme1:
Figure 1. Structure formulas1
Under an open flame in the hood, 12 capillary micropipettes were made. Two silica TLC plates were obtained, along with a development chamber. Each plate was prepared and labeled appropriately with a lead pencil. The first plate was spotted with acetaminophen, aspirin, caffeine, salicyclamide, and reference. The second plate was spotted with Anacin, Bufferin, Excedrin, Tylenol, and reference. The development chamber was then brought to the hood where 0.05% glacial acetic acid in ethyl acetate was poured into the chamber. The first plate was placed in the chamber until the solvent was approximately 0.5cm from reaching the top. Once dry, the plate was placed under the UV light to observe the differences in the over-the-counter drugs. A circle was drawn around each dot that formed so a measurement could be taken to help determine the Rf value. The same steps were taken with the second plate as were done with the first. After all observations and measurements were taken the two plates were both plates were placed in a chamber with iodine crystals and then was heated with body heat from the hands until the formation of dots was noticeable. Both plates were taken out and observed to find similarities and differences.
Data:
Name
Formula
MW
(g/mol)
Amount
Moles
State
Density
(g/cm3)
Melting Point (°C)
Boiling Point (°C)
Theo. Yield
Hazards
Acetaminophen
C8H9NO2
151.17
______
_____
Liq.
1.2639
169
>500
____
References: 1. Rxlist the internet drug index. (2012, February 15). Retrieved from http://www.rxlist.com on January 26, 2013 2. Radke, K., Stolzenberg, G. “Organic Chemistry: Laboratory Manual”, 3rd ed. Cengage Learning. N.D. 2009