Thin layer chromatography rf-华强电子网

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First prepare a thin layer plate, that is, uniformly apply the adsorbent on a glass plate of appropriate size, the thickness is less than one millimeter, and then point the sample solution at a distance of 1.5 cm from the bottom edge to form a small point called "origin". Place the thin plate in a glass jar containing the mobile solvent (this solvent is called “expansion solvent” and the glass cylinder is called “expansion groove”). When the solvent spreads along the thin layer to a certain distance above the origin (Generally 10-12 cm), take out the thin layer plate, record the distance from the origin of the solvent expansion front edge to the origin A. Then use the spray coloring reagent or ultraviolet light to illuminate the separated compound. This process is called “display”. Spectrum. Observe and record the distance from the center of the spot. The position of the spot on the thin plate is usually expressed by the ratio of the displacement value (Rf). The Rf value is the distance from the origin of the spot to the origin and the distance from the origin of the solvent unfolding front. Ratio

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Distance from the center of the spot to the origin

Rf=───── ──────

The distance from the solvent front to the origin

The Rf value is a value related to the partition coefficient of a substance in two phases, and therefore, is a constant under certain conditions. Different substances have different Rf values ​​due to the difference in partition coefficients between two phases under specific chromatographic conditions, so that To achieve the purpose of thin layer chromatography separation.