Thin Layer Chromotography Discussion

Adsorption chromatography occurs when “one substance form[s] some sort of bonds to the surface of another one”, creating intermolecular forces between the two substances (Chemguide). For thin layer chromatography, the components of the mixture are adsorbed onto the stationary phase that covers the plate (Chemguide). The more polar a substance is, the more strongly adsorbed it is (Chemguide) and the strong intermolecular forces then result in a slower rate of migration with respect to the moving phase. As the solvent touches the TLC plate, the solute (mixture) is allowed to move up the TLC plate

In the beginning of this experiment, our TA added water, salt, and 75/25 hexane/acetone to spinach leaves to a blender and blended the mixture to assume equal amounts for each group and to avoid erros if each student had to do the blending. The addition of the water to the mixture allowed the it to separate into a distinct organic layer after being run in a centrifuge, which was available to be collected at the top of the centrifuge. Salt reduces solubility, which will force the organic parts of the mixture (the desired pigments for example) to separate into the organic layer at the top. Lastly, 75/25 hexane/acetone is added because this is a moderately polar solvent and will useful for both the non-polar and polar pigments present within the spinach leaves. A mixed solution of hexanes and acetone must be used because acetone is very polar, while hexane in very non-polar, and the spinach leaves contain both non-polar and polar pigments in them that are important in the extraction and for further analysis. The mixture was placed in the centrifuge so the solids in the mixture (mostly cellulose) could be separated from the liquids into separate distinct layers for further extraction and testing. In the tube, the organic substances separated into the top layer, whereas the water layer remains at the bottom of the tube below the solid layer made up of mainly cellulose.

The stationary phase will absorb or slow down different components of the tested solution to different degrees creating layers as the components of the solution are separated. Chromatography was invented by the Russian botanist, Mikhail Tsvet. Chemists use this process to identify unknown substances by separating them into the different molecules that make them up.

Chromatography is a fairly simple process. First, you put a dot of ink(or in our case, the M&M food dye) near the bottom of some chromotography paper (also known as filter paper), and then hang the paper vertically with its lower edge (the one closest to the spot of dye) dipped in a solvent (In our case, the sodium chloride solution). Capillary action forces the solvent to travel up the paper, where it meets and dissolves the ink. The dissolved ink (which is the mobile phase) slowly travels up the paper (the stationary phase) and separates out into its different elements. Another way of describing it is to think of the liquid as an adhesive-like liquids, some of which stick more to the solid and can travel more slowly than others. This is

First, dichloromethane was the least polar solvent, so it barely moved up the plate. Hence, the spots on the TLC plate stayed at almost the same place they were spotted on, and separation did not occur. As a result, the retention factor (Rf) values for these components were too small. In addition, the second solvent, methanol, was the most polar solvent out of the three, and the solvent moved up the plate too quickly. This resulted in the components moving up the plate based on the solvent's polarity instead of their own, and a smear of all components at the solvent front was observed. Hence, the Rf values could not be determined. Lastly, ethyl acetate, a moderately polar solvent, moved up the plate with moderate speed. This gave the components time to move up the plate according to their polarity, and the Rf values could be used to identify the unknown compound. According to the TLC method with ethyl acetate solvent, the unknown compound had the same Rf value with acetanilide (Rf = 0.40). As a result, the unknown compound was identified as

On a thin chromatography plate, five spots were placed ( as shown in table 2) and the plate was developed using chloroform/methanol. This was later visualized with dragendorff’s reagent under the UV light. All separated components were observed, identified and recorded.

Thin Layer Chromatography (TLC) Plating: This is a common method that is used to monitor the progress of a reaction and determine when it is complete. In our

Chromatography is used to separate mixture of chemicals to figure out what compound are present in the chemical, the chemical that are suitable to separate is by chromatography that include inks, dyes and colouring agents in foods. The experiment is carried out on paper where you put a spot of the chemical near the bottom of a chromatography piece of paper and the paper is in a solvent which is usually water. When the solvent (water) soaks up the paper it carries the chemical up with it. Different components of mixtures will move at a different rate as other, some would move faster or slower than others which separates the mixtures from each other. They all have a stationary phase that is a solid or a liquid supported on a solid. A mobile phase is a liquid or a gas.

Thin Layer Chromatography (TLC) is one of the oldest chromatographic techniques used for the identification of compounds and for determination of the presence of trace impurities.

Figure 1: Photo of Thin-Layer Chromatography using a beaker to hold the solvent. Photo by: Emily Olsen

Goal: The first goal of today’s laboratory is to separate components of spinach dyes using different eluants. The four eluants will be using are ethanol, chloroform, 9:1 petroleum ether : ethanol, and petroleum ether. The second goal of the lab is to separate fluorine and fluorenone by column chromatography. Thin layer chromatography (TLC) was used to measure the polarity and separate the components in the mixtures. TLC was chosen because of its simplicity, high sensitivity, and speedy separation. For each part of the lab, we measured the retention factor on the TLC plate. To measure the retention factor, we used the formula:

The chromatography process works by differences in polarity of the compounds present. Organic molecules will bind to fine particles of the silica gel by intermolecular forces. Non polar compounds such as aromatic compounds bind to the silica gel via weak van der Waals forces. Polar compounds will bind to the silica gel more strongly via dipole-dipole interactions, hydrogen bonding. When examining TLC plates the following general rules will apply: The role of the solvent is to move the compound through the solid media. A non-polar solvent will dissolve non-polar compounds. The non-polar compound will move most rapidly through the solid media with the solvent. A polar compound is more tightly bound by the silica gel via stronger intermolecular

Thin layer chromatography can be used as a physical method to segregate compounds from natural sources. E.g. Spinach leaves are visibly green, but consist of a variety of components that have more colour than others. This experimental procedure uses compounds from spinach leaves that are exposed to chromatography, TLC plate to indicate the different pigments

Chromatography is a separation technique in which the mixture to be separated is dissolved in a solvent and the resulting solution, often called the mobile phase, is then passed through or over another material, the stationary phase. The separation of the original mixture depends on how strongly each component is attracted to the stationary phase. Substances that are attracted strongly to the stationary phase will be retarded and not move alone with the mobile phase. Weakly attracted substances will move more rapidly with the mobile phase.

The word chromatography, which is gotten from two Greek words actually signifying "shading composing", was instituted toward the start of this century when the system was initially used to isolated hued segments of plant takes off. Today, the name is somewhat deceptive, in light of the fact that most types of chromatography don 't rely on upon shading. A few sorts of chromatography are generally utilized, among which are paper chromatography, slender layer chromatography or TLC, fluid chromatography, gas chromatography, and superior fluid chromatography or HPLC. Chromatography is useful to the point that some structure can be found in most logical research centers the world over. For instance, in measurable science wrongdoing research centers, the FBI keeps up a library of chromatograms of inks that are utilized industrially. In the first case in which chromatography of inks were utilized, a man in Miami distorted travel and cost vouchers. Notwithstanding, the ink pen he utilized had ink that wasn 't accessible monetarily until 3 years after the outings had occurred. The hypothesis behind chromatography is to permit a blend of diverse chemicals to be conveyed or divided between a stationary stage and a portable stage (eluent or dissolvable). The versatile stage may be a fluid or a gas; the stationary stage is ordinarily a strong. As the portable stage streams over the stationary stage, the parts in the blend are conveyed along. The more solvent a part is in the