Organic Chemistry 333L, section 03M LaboratoryPost-LabThin Layer Chromatography of Analgesics (TLC)By: Cameron Kahn8 October 2013TA: James Collie1 | P a g eResults:The thin layer of chromatography paper (TLC) was measured to be a length of 9cm from top to bottom. The solvent front was measured to be 7.0cm from bottom to the point at which it stoppedmoving up. The baseline was measured to be 1cm from the bottom of the paper. The four analgesics used in this experiment were; Aspirin (acetylsalicylic acid), Acetaminophen, Ibuprofen, caffeine, and the unknown “A” sample. The two phases in this experiment were stationary (adsorbent which was silica gel) and mobile phase (solvent which was comprised of 95% ethyl acetate and 5% acetic acid) (Handy). The mobile phase of Aspirin was 5.75cm with anRf value of 0.821. The mobile phase of Acetaminophen was measured at 4.50cm with the Rf value of 0.643. The mobile phase of Ibuprofen was 1.40cm with an Rf value of 0.20. The mobile phase of caffeine was 6.50cm with an Rf value of 0.929. Lastly, the mobile phase of sample “unknown A” was measured to be 4.40cm with an Rf value of 0.629. From comparing the Rf values of each solutions being tested, the unknown sample had similar Rf value of Aspirin. Observations:The TLC plate had a white front with a clear plastic backing. The adsorbent on the TLC plate was the white front which was presumed to be either silica gel or alumina on the basis that the two are the most commonly used adsorbents on any TLC plates (UC Boulder). The solvent used in the experiment was clear. The initial colors noticed from each drop of solution on the TLC paper were as follows: Aspirin was clear, Acetaminophen was a faint/light yellow hue, Ibuprofenwas clear with no noticeable color, Caffeine was white in color, and Unknown “A” was a faint/light yellow. A strong odor from the ether was noticed with no smell coming from the TLC paper. While performing the experiment one could see the TLC place become moist but he/she could not see the compounds. Once the TLC plate was exposed to UV light, the distance the compounds traveled could be observed. The solutions tested presented themselves as light brownto dark brown spots.Calculations:CompoundsRf=distancetraveld by compounddistancetraveled by solvent*measured in centimeters *no units for RfAspirin5.757.0=0.8214 RfAcetaminophen4.507.0=0.6428 RfCaffeine6.507.0=0.9286 Rf2 | P a g eIbuprofen1.407.0=0.20 RfUnknown4.407.0=0.6286 RfConclusions:This experiment was very fast and uneventful. The experiment showed how TLC works which isto say that the solvent and tested solutions will travel up the adsorbent layer on the TLC plate through capillary action. The results from the differential partitioning between the compounds can be used to determine the response factor for each compound being tested. There are many uses of TLC which includes: determining the number of compounds in a mixture, determining good solvent systems for column chromatography, identifying substances, monitoring progress of reactions, and monitoring purification processes (Handy). Acetaminophen and the unknown had similar Rf value around 0.64. From this, he/she could assume that the unknown is Acetaminophen. If two substances give identical Rf values using the same solvent systems locations, then it is possible that the two substances are identical. It is also very possible that two different substances could give relatively similar Rf values, but not identical[ CITATION Geo121\l 1033 ]. Since the unknown and Acetaminophen share very similar Rf values, it is safe to say the unknown is Acetaminophen. An important piece of information to remember is that there is a limit of detection when using TLC to identify substances; there is no guarantee that a single spot corresponds to a single substance. Sources of error could have come from not apply a top to the beaker to cuts the experiment off from the outside atmosphere. The atmosphere can change how the compounds travel up the adsorbent which in turn affects the Rf values. Also human error occurred when measuring the distance traveled; when deciding on the measurement, one could have “eye balled” the distance rather than using a ruler with centimeters.IR-spectroscopy:No IR-analysis was done. Included is a picture that identifies each part of the experiment.3 | P a g eLeast polar compound Most Polar compoundIbuprofen Aspirin Acetaminophen CaffeineReferences: 1. Ali, George Handy and Salman. Chemistry 333 & 334 laboratory Manual Experiemnts inOrganic Chemistry Fall 2012 - 2013. Montgomery, Al: QDE Press, Fall 2012.2. "Thin Layer Chromatography (TLC)." Thin Layer Chromatography (TLC). CU Boulder, n.d. Web. 06 Oct. 2013.3. Millar, Sarah. "Tips and Tricks for the Lab: Column Choices." Chemistry Views. N.p., 03 July 2012. Web. 06 Oct. 2013. (figure1)4 | P a g eFigure