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Duc Chau TA-Alexander Holter Chem 237-517 Thin Layer Chromatography Results and Discussion Results For this lab experiment, Thin Layer Chromatography techniques were used to identify the active ingredients in commercial analgesic. The common analgesic that was chosen for this lab named Excedrin Tension. Firstly, 75%- Ethyl Acetate to 25% Hexane solvent was poured into the TLC chamber. Secondly, a small amount of Anacin was poured into a 50-mL beaker in addition of mixing with 4mL of methanol. TA then gave two TLC plates to perform the experiment. A dash line was drawn for both TLC plates above the solvent from TLC chamber to indicate the starting point. After dotting all the six analgesics and the given common analgesic on both TLC plates. Both TLC plates were then transferred into the TLC chamber facing back to back with cap closed to let the solvents ascend. After about 10-15 minutes of waiting, two TLC plates were taken out from the chamber and got immediately marked the solvent font before it faded away. The two TLC plates were taken into the UV lamp to observe its activity. The Rf values were then measured and recorded in the table below. The analgesic was assigned for this lab experiment was Anacin.

Table 1 Six Common Analgesic

S1

S2

S3

Naproxen

Ibuprofen

Acetaminophen Caffeine

and Caffeine

S4

S5

S6

Ibuprofen

Aspirin

Table 2 Rf values from in-lab

Anacin

S1

S2

S3

S4

S5

S6

Rf=0.12 cm,

Rf=0.91 cm

Rf=0.09 cm

Rf= 0.78 cm

Rf=0.12 cm

Rf- 0.39 cm

Rf= 0.22 cm

0.65 cm, 0.12

Rf=0.86 cm

Rf= 0.66 cm

cm, 0.68 cm Rf2= 0.09 cm, 0.61 cm, 0.09 cm, 0.64 cm

The data that were recorded in-lab were then get compared to data on Ecampus to different solvent. The results are shown below. Table 3 Anacin of Ethyl Acetate on Ecampus

Anacin

S1

S2

S3

S4

S5

S6

Rf=0.17 cm,

Rf=0.17 cm

Rf=0.41 cm

Rf= 0.13 cm

Rf=0.22 cm

Rf- 0.61 cm

Rf= 0.12

0.41 cm, 0.13 cm, 0.68 cm Rf2= 0.13 cm, 0.48 cm, 0.14 cm, 0.49 cm

Rf=0.64 cm

Table 4 Compounds identify on Ecampus

S1

S2

S3

Naproxen

Acetaminophen Ibuprofen and

S4

S5

S6

Aspirin

Ibuprofen

Caffeine

Caffeine Discussions Comparing data that were done in-lab to data were given on Ecampus, one can assumed that 75% Ethyl Acetate-25% Hexane is the best solvent at separating the standards analgesic. This is most likely due to being an intermediate polarity so that it can still drag the solute down the plate while letting the separate according to their compound activities and reactiveness. On the contrary, Hexane was too nonpolar, so it could not attract the analgesic down the plates as the analgesic did not move from their starting line except for Naproxen. While Ethyl Acetate was able to drag the analgesic down the TLC, but it did not separate some of the compounds. It is due to Ethyl Acetate being a polar compounds, so it only move polar compounds off the starting point while leaving non-polar compounds behind, Therefore, the best solvent is 75% Ethyl Acetate to 25% Hexane is the best solvent as it moves both polar and non-polar compounds off the starting point. Furthermore, judging from looking at the Rf values from Ethyl Acetate, some of them are higher than 75% Ethyl Acetate-25% Hexane. However, when looking at the TLC plates of Ethyl Acetate, there was only one double dots, which was Ibuprofen and Caffeine. This is due being polar molecules attracts polar molecules. Finally, the active ingredients in Anacin were found to be Caffeine and Aspirin. This is due to having similar Rf values calculated. Aspirin has Rf of 0.66 cm which is nearly identical to

one of the Rf of Anacin, 0.65 cm. Addition, Caffeine Rf was calculated to be 0.12 cm which is identical to the first Rf value calculated for Anacin, 0.12 cm. Furthermore, a mixture of Caffeine and Ibuprofen Rf values were also calculated and Caffeine’s Rf value also matched with the third Anacin Rf value, 0.09 cm.

Errors As always, there are always errors in every lab. For this experiment, sources of errors come from spotting because there some that was dotted too much, and some are not enough hence some strange looking dots on TLC plates. This could affect the travel distance and Rf, of course, would get affected by this. Secondly, the data were not correct written in order because they did not match with data on Ecampus as far as S1, S2, etc. concerns. In conclusion, TLC is a useful technique when trying to find out the identity of the compound and separating compounds. It is also to see polarity of compounds. Overall, the lab was successful because all the TLC techniques were used correctly and was able to see compound separation under UV light despite some mistakes that could potentially cost the data for the lab....