Thin Layer Chromotography Discussion

Thin Layer Chromatography (TLC) is an extremely useful technique for monitoring reactions. It is also used to determine the proper solvent system for performing separations using column chromatography. TLC uses a stationary phase, usually alumina or silica, that is highly polar (standard) or non-polar (reverse phase), and a mobile phase, some solvent whose polarity you will choose. In 5.301, and in most lab applications, you will use standard phase silica plates. You will apply your reaction mixture in solution to the plate then "run" the plate by allowing a solvent (or combination of solvents) to move up the plate by capillary action.

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

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.

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.

Thin Layer Chromatography (TLC) works in relation to the polarity of chemicals. A plate is first covered with aluminum foil or silica etc. and has solutions of varying polarities placed upon the aluminum foil or silica. When placed in a in a puddle of solvent that moves up the plate, the different inks i.e. the solution will move up the place based on their Rf values. Adherence increases with increasing polarity, so the less polar compounds will be carried farther by the solvent. Eventually the dyes will separate into their compontnets, which can be visibly seen. This is then used to determine who the ink of the unsigned note belonged to along with the pen that it belonged

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.

To determine what is present in the unknown, if the unknown and known substances spotted on the same TLC plate give spots in identical locations and R_f values are the same, then they may be identical. Ultraviolet light (UV) and iodine vapor are two techniques that can be used to visualize the nitroanilines in a developed TLC plate. In the case of UV light, because the absorption of UV light is found in organic functional groups containing chromosomes, such as nitroanilines, this technique can help visualize colorless compounds. In addition, iodine vapor can be absorbed by most organic compounds substances like nitroanilines except alkanes and alkyl halides. Once absorbed, the substance will appear as brown spots on the plate. A TLC plate can

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 isolation and purification of phosphatidylcholine from egg yolk is successfully achieved through aluminum oxide chromatography. The chromatography-purified fractions of PC is concentrated by doing thin layer chromatography. The TLC plate from first two fractions showed indication of PC, which describes the separation is very faster than the typical experiment. Usually fractions 5-9 contains the highly concentrated PC ( Clingman ).The net weight of the PC obtained after all the purification is 1.14grams.The TLC analysis between crude PC and purified PC is compare with standard lyso PC.The purified PC and crude PC has same Rf value but crude PC has additional spots that are not present in purified run. Since the purified PC has one prominent

After this, assuming no complications, the ratio of these compounds is 2.0 to up to 4 or more at 40 weeks. Infants who have a ratio of 2.0 or more rarely develop RDS (Wardelab.com, 2017). It denotes alveolar stability and lung maturity. After extraction, the L:S ratio can be measured using Thin Layer Chromatography (TLC). TLC is a useful technique for separation and identification of a compound(s) when in a mixture. Compounds are separated by their differences in their solubility. There are two phases to separate the mixtures, mobile phase and stationary phase. In this experiment the mobile phase is the solvent which is chloroform:methanol:water in ratio 13:5:0.8 v/v. The stationary phase is the TLC plate, coated with silica gel. When the samples are spotted at the bottom of the TLC plate. It is then placed in a container containing the solvent (mobile phase). The solvent will then move up the TLC plate by capillary action, moving the mixtures at different rates, thereby separating them. When the solvent nearly reaches the top, the TLC plate is removed and the solvent front is

Chromatography is a process commonly used to separate substances in accordance to their differential distribution between what is referred to as a stationary phase and a moving or ‘mobile phase’. There are a variety of different types of chromatography some include; paper chromatography, gas chromatography and high performance liquid chromatography.

Chromatography Investigation Chromatography is a highly regarded technique used to separate the components of a mixture. It is based on the principle that each component possesses a unique affinity for a stationary phase and a mobile phase. The components that are more inclined to enter the mobile phase will migrate further on the chromatogram and distinguish themselves from the other components. The type of solvent used in chromatography is known to directly affect the separation of the mixture. In this experiment, thin-layer and column chromatography will be utilized to separate the numerous chlorophyll and carotenoid pigments of a spinach extract.

However, each is kind is used specifically to amplify certain findings. Hence, the gas chromatography is the most sensitive in detecting compounds of a mixture and is used mostly to analyze organic compounds that can be vaporized without decomposition [Padias pg. 179]. In addition, the column chromatography is a cost efficient way to separate components based on polarity and it is flexible on what is used. The last common type of chromatography, thin layer chromatography, can be used to show how long it takes for a reaction to go from reactants to products over a period of time.

[3] M.G. Dauyvis et al., J Agric. Food Chem., 2002, 50, 1548-52. Role of Ri