Expt 81 Thin Layer Chromatography TLC
Expt. 8.1 Thin Layer Chromatography (TLC) Analysis of Analgesics
Krista Jinks
CH 211L
Section F
10/27/14
I. Abstract: The objective of this experiment was to analyze analgesic tablets by TLC to determine what analgesics they contain. The analgesics that could be in the tablets included ibuprofen, acetaminophen, aspirin, and caffeine. Through the use of TLC, unknown substance #62 was found to be Bayer Aspirin because it only contained aspirin.
II. Introduction:
1. Briefly describe the process of Thin Layer Chromatography. Make it clear in the discussion what the stationary and mobile phases are and how they work together to effect the mobility of a substance in TLC. This is in general terms, not specifics for this lab.
Thin Layer Chromatography is done by using a thin layer of absorbent material that is attached to a glass layer. The absorbent material is the stationary phase, which is a silica gel. Silica gel allows for particles to bind to. A small amount of the mixture that is being analyzed in applied to the bottom and placed in a pool of solvent and placed into a chamber. The solvent is the mobile phase and it slowly rises up the TLC plate. The components rise with the solvents and they differ in solubility. Some components will rise higher than others so this is how they are separated. (Williamson 164)
2. What problem will ensue if the level of the developing liquid is higher than the applied spot in a TLC analysis?
The applied spots will be washed off because they become submerged in the liquid. (Williamson 164)
3. Explain what the Rf value is and describe its usefulness.
The Rf value is the chromatographic parameter. It is the retention factor that is expressed as a decimal factor. It is the distance the spot travels over the distance the solvent travels. The Rf values are used to determine unknowns and the amount of molecules in a mixture. (Williamson 167)
4. Based on the number and polarity of the functional groups in
Krista Jinks
CH 211L
Section F
10/27/14
I. Abstract: The objective of this experiment was to analyze analgesic tablets by TLC to determine what analgesics they contain. The analgesics that could be in the tablets included ibuprofen, acetaminophen, aspirin, and caffeine. Through the use of TLC, unknown substance #62 was found to be Bayer Aspirin because it only contained aspirin.
II. Introduction:
1. Briefly describe the process of Thin Layer Chromatography. Make it clear in the discussion what the stationary and mobile phases are and how they work together to effect the mobility of a substance in TLC. This is in general terms, not specifics for this lab.
Thin Layer Chromatography is done by using a thin layer of absorbent material that is attached to a glass layer. The absorbent material is the stationary phase, which is a silica gel. Silica gel allows for particles to bind to. A small amount of the mixture that is being analyzed in applied to the bottom and placed in a pool of solvent and placed into a chamber. The solvent is the mobile phase and it slowly rises up the TLC plate. The components rise with the solvents and they differ in solubility. Some components will rise higher than others so this is how they are separated. (Williamson 164)
2. What problem will ensue if the level of the developing liquid is higher than the applied spot in a TLC analysis?
The applied spots will be washed off because they become submerged in the liquid. (Williamson 164)
3. Explain what the Rf value is and describe its usefulness.
The Rf value is the chromatographic parameter. It is the retention factor that is expressed as a decimal factor. It is the distance the spot travels over the distance the solvent travels. The Rf values are used to determine unknowns and the amount of molecules in a mixture. (Williamson 167)
4. Based on the number and polarity of the functional groups in
Cited: Williamson, Kenneth L.; Minard, Robert D.; Masters, Katherine M. Macroscale and Microscale Organic Experiments, 5th ed., selected chapters; Houghton Mifflin Co.; New York, 2007.