Chromatography separates the components of a mixture. TLC (Thin-Layer Chromatography), Column Chromatography, Gas Chromatography, and High Performance Liquid Chromatography are different variations, but they all rely on a mobile phase (gas, solvent) and a stationary phase. These phases are chosen so that each solute has a high affinity for one and a low affinity for the other and therefore can be separated. TLC plates are prepared by putting a spot of the dissolved solute onto the stationary phase which is on the plate. Then it is developed by standing the plate in a beaker that has a bit of solvent in the bottom. By capillary action, the solvent rises and wets the plate, separating the components of the mixture, which can be compared by how far they travelled along the plate (the Rf value). The relative polarities of the solvent and solutes generally determine Rf.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.