Thin Layer Chromatography or TLC is a technique used as separation and as an identification technique. There are many forms of chromatography, but one thing that remains constant throughout all of the types of chromatography is that there is a stationary phase and a mobile phase. In the case of TLC the stationary phase is the silica gel on the TLC tray. The mobile phase is the mixture that is being separated. In this lab TLC will be used to compare the polarity of certain mixtures and also to gain a better understanding of what TLC is about.
TLC is performed by taking a TLC plate and using a pencil making a mark where you are going to be placing the drops, the mark and where you put the drop needs to be approximately 1.0 cm from the bottom of the plate. Be sure not to touch the plate as it will change the results of the reading.The TLC plates that were used were a thin sheet of plastic coated in silica gel. A capillary tube was used to place a single drop of Ibuprofen, Acetaminophen, Caffeine, and Aspirin, between or on the marks of the TLC plates. A sample of an unknown compound was placed on the third plate using the same method. The TLC plates were set aside and 7.0 mL of 70% Ethyl Acetate and 3.0 mL of 30% Petroleum Ether was measured out and placed in a small beaker and covered with a watch glass. The remaining amount was taken and placed into three jars making sure that the level of the solvent is just enough to cover the bottom of the jars and not to exceed the pencil mark on the TLC plates. Two plates of the know compounds were placed into two jars and one plate with an unknown compound was placed in the remaining jar. The plates were placed in the jars at a 45º angle and the caps of the jars were loosely placed on top. Being sure not to move or disturb the jars during this process; the solvent was observed as it slowly ran up the TCL plates and when it was approximately a centimeter from the top, the plates were...