Paper chromatography is a method for testing the purity of compounds and identifying substances. It is relatively quick and requires small quantities of material. The 5 thumbnail images summarize the content of the video. Click an image to see the image gallery.
Initially the spots are completely adsorbed onto surface of the stationary phase. As the liquid level rises and meets the spots, the sample partially dissolves in the mobile phase and travels up the plate with it. Different substances will travel different distances along the plate. The distance that a substance will travel depends on how strongly it adsorbs to the stationary phase versus how much it dissolves in the mobile phase. The more a substance adsorbs, the less it dissolves and the less it moves along the plate such as the first purple spot. The less a substance adsorbs, the more it dissolves and the farther it travels such as the yellow spot. In this manner, a mixture of substances may be separated such as the middle sample, which was composed of the yellow and purple substances originally.
Paper chromatography is one method for testing the purity of compounds and identifying substances. Paper chromatography is a useful technique because it is relatively quick and requires small quantities of material.
Separations in paper chromatography involve the same principles as those in thin layer chromatography. In paper chromatography, like thin layer chromatography, substances are distributed between a stationary phase and a mobile phase. The stationary phase is usually a piece of high quality filter paper. The mobile phase is a developing solution that travels up the stationary phase, carrying the samples with it. Components of the sample will separate readily according to how strongly they adsorb on the stationary phase versus how readily they dissolve in the mobile phase.
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