Chromatography Lab Report

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Because most substances are colorless, the separation caused by thin-layer chromatography can go unnoticed until the compound is visualized. If fluorescent plates are used, the number and distance traveled of compounds can be seen by illuminating the plate with ultraviolet light (Saferstein, 2011). The materials on the plate will appear as bright spots on a dark background, where they can then be circled with pencil. For molecules that are not activated by UV light, the chemical stain iodine proves effective for visualization. Treated plates are placed in a jar with iodine crystals, staining all organic compounds brown (UC Davis Chemistry Department, 2013). While simplicity and cost-effectiveness lend themselves to the popularity of thin-layer …show more content…
Similar to capillary action chromatography, components of varying polarities will travel down the column at different rates; because molecules belonging to the same compound will travel together, the compounds are separated into distinct bands of colors within the glass column, as evident in Figure 3 (UC Boulder, 2015). If the solvent moves down the column by air pressure instead of gravity, it is known as flash chromatography. Column chromatography was the brainchild of Russian botanist Mikhail Tswett, who was able to separate plant pigments using glass columns filled with calcium carbonate (New World Encyclopedia, 2013). Then in 1978, Clark Still introduced a modification to column chromatography that was faster and more efficient than gravity-fed chromatography, claiming it could be "done in a flash" (UC Boulder, 2015). It differs from the conventional technique because it uses 10-15 psi from an attached air pump to drive the solvent through the column, allowing separation that used to take days to be made in hours (New World Encyclopedia,