Davis_Lab 4 TLC Report.docx - Lab 4 Report Thin Layer...

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Lab 4 Report: Thin Layer Chromatography Pre-Lab Chromatography is a laboratory technique that is used to separate and purify mixtures. It utilizes the molecular interactions between the compound with two phases, one stationary and one mobile. The solvent carries the compound through a solid absorbent, usually silica which is very polar. The rate of movement depends on the polarity, hydrogen bonding, and size of the molecules in the mixture which causes the different materials to migrate different distances. More polar components will spend less time in the mobile phase migrating a shorter distance, while less polar compounds will migrate further, effectively separating and/or showing the purity of the material. Diagram of TLC Plate Calculation of R f value R f = distance spot traveled/distance solvent traveled Procedure Prepare a dilute solution of your sample that is neither too dilute or concentrated. Use a pencil to draw spots for the number of lanes you will need to perform a TLC for. Use a TLC plate spotter to spot the diluted sample on the spots you made and visually confirm that there is enough sample on the plate or use a UV light to do so. Place your chosen solvent system into a beaker making sure that the level is below spots, but above the bottom of the plate. Cover the beaker to ensure that the vessel is fully saturated with the solvent. Place the TLC plate evenly into the chamber. Once the plate has fully developed, quickly mark the solvent line and circle where the compounds have moved and calculate the R f values.
Data/Observations Experiment 1: Analgesics TLC Plate Lanes Solvent System Plate 1 A: acetaminophen B: aspirin C: unknown A D: caffeine E: ibuprofen 5% acetic acid Plate 2 A: acetaminophen B: aspirin C: unknown A D: caffeine E: ibuprofen 1:2 ethyl acetate/hexanes Plate 3 A: acetaminophen B: aspirin C: unknown A D: caffeine

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