Essay about TLC Analysis of Analgesic Drugs

1307 Words Feb 18th, 2014 6 Pages
January 24, 2013
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.
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Due to the appearance of the spots on each plate, a preliminary assumption of the components in each medication was determined. It was concluded, by strictly looking at the spots and their colors, that Anacin’s component was caffeine, Bufferin’s component was between aspirin and salicyclamide, Excedrin’s components were caffeine and acetaminophen, and Tylenol’s component was acetaminophen.
The appearance of the spots under the UV illumination was not enough to determine the specific components in each over-the-counter drug, so the Rf values were evaluated to further conclude the experiment. The Rf value is the ratio of distance travelled by the solute to the distance travelled by the solvent front.2 According to table 2 and table 3, a comparison can be made between the Rf values. Anacin’s component is caffeine, Bufferin’s component is salicylamide, Excedrin’s component’s are caffeine and acetaminophen, and Tylenol’s component is acetaminophen. These results, as compared to the those of the UV illumination, are similar, except for Bufferin. In the UV illumination, it was hard to determine which spot was closest to the that of Bufferin when comparing it to the reference plate because aspirin and salicylamide appeared to be very similar in distance. After the Rf values were determined, it was easier to see that Bufferin’s component (table2 and table 3) was salicylamide due to fact that they shared the same Rf value, 0.86 cm. While looking at the TLC

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