Paper Chromatography Lab Report

Background: 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.

Depending on the polarity of the components of the mixture, different compounds will travel different distances up the plate. More polar compounds will "stick" to the

The intermolecular forces are pulling the molecules between the stationary phase, the chromatography paper and the mobile phase, the solvent. The molecules of the chromatography paper are trying to pull the molecules to where they are while the molecules of the molecules with them to the top of the paper. 4. Draw a picture of how the chromatography worked. Explain your picture using the following terms: stationary phase, mobile phase and intermolecular forces.

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

(a) (3 pts.) This video discusses 3 different types of chromatography. List each one mentioned, and describe their differences in as much detail as possible (your points earned will be proportional to the level of detail in your discussion). Which one was used in this lab demonstration?

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

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

The first part of this experiment uses thin layer chromatography (TLC) while the second part involves column chromatography

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.

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

When reacted with different subjects or by means of physical separation. Chromatography works through a system of “partitioning compounds between a stationary phase and a moving phase.” This happens when the tubular capillary columns are packed with an inert solid with pores, which supports the “stationary” liquid phase. The solutes then become strongly held by the stationary phase and move slowly into the mobile phase, those who do not “stick” with the stationary phase are the ones that move faster into the mobile phase. In the mobile phase, usually made up of a gas, (nitrogen or helium).

During the first part of the experiment a dot of ink was placed onto chromatography paper to separate the mixture by pigment. This chromatography paper was place so that a portion of the paper below the dot was in water, so that the water could travel up the paper and separate the ink. The paper was suspended using a toothpick that was put through the top of the paper, which was held by the neck of the bottle.

The following procedure dealt with a chromatogram. The materials needed are: a pencil, safety goggles, scissors, chromatography paper strip, capillary tube, spinach plant pigment extract, test tube, cork stopper, graduated cylinder, chromatography solvent (alternative isopropyl alcohol), metric ruler, stopwatch or clock with a secondhand, hook/fashioned paperclip, paper towels, test tube rack, and mortar and pestle. First we obtained a strip of chromatography paper and cut it so it would fit inside a test tube (with it barely touching the bottom of the tube). Also, when touching the strip, touch the sides only. Then we attached (firmly) the top of the strip to a hook (or fashioned paperclip at bottom of the cork stopper). Make sure it fits in the test tube. Next we used the pencil to draw a faint line across the strip two centimeters from the bottom tip of the strip. We placed the cork and strip in place, and we put a mark on the test tube one centimeter below the top of the stopper.

The type of solvent used will determine the extent of separation of each component. The concept that like constituents are attracted to each other and are miscible plays an essential role in determining the migration distances of various components of the mixture. Each component has the option of entering either the mobile or stationary phase and the polarity of the solvent will influence its pathway. For example, a more polar solvent will compete with the polar components for positions on the polar adsorbent and also transport its counterpart along the plate until it finally becomes adsorbed. As a result, the polar components of the mixture will remain in the mobile phase for a longer period

Gel-Filtration Chromatography is a commonly used method used in order purify a protein from a mixture, by means of separations. Different biomolecules differ in size, or their molecular weight. In the gel matrix inside the chromatography column, there are gel beads which are porous to allow certain sized molecules to enter. The molecules that are able to enter the pores of the gel, are held in stationary phase and will elute from the column later on, these are usually smaller, to medium sized molecules. Larger molecules that are not able to fit in the pores will elute out of the column first, they are involved in mobile phase where they just go straight through the column without interacting with the gel beads. Smaller molecules will have a higher elution volume, while the larger molecules will have a lower elution volume. The volume to elute the protein is inversely proportional to the molecules size.