Case Study Questions: Questions And Questions On Chromatography

In a test known as solid phase micro-extraction, SPME, a phase-coated fiber that is contained within a syringe is exposed to the sample being tested². In this case, when Jones³ had collected all of the polyacrylate for that particular time of day, she would take the fibers back to the lab in a cooler full of ice. This was to ensure that none of the chemicals escaped from the cloth while in transit to be analyzed. In order to analyze the fibers, the chemicals were extracted by withdrawing the fiber from the needle, the needle is then removed from the sample vial and introduced into the gas chromatography injector⁴. After Jones had analyzed the fibers using Gas Chromatography (GC), she had determined that the major contributors to decomposition were cadaverine, putrescine, skatole, and indole [Figure 1]. Each of these chemicals produce their own distinct odor⁵ and is present at different stages of the decomposition

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.

The three molecules separated because chromatography paper is made of cellulose. Cellulose is polar, therefore ‘like attracts with like’. As the solvent interacts with the paper, it competes for

This is how we separate the different compounds in the mixture because they go at different rates. This process is slightly similar to gel electrophoresis in biology. In the fact that both separate at different speeds. For gel electrophoresis the smaller fragments move faster than the large ones. In adsorption column chromatography, the compound that is more attracted to the liquid phase, the mobile phase, will move faster than the one attracted to the stationary phase.

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.

1. Paper Chromatography is a method used for the separation of colors which are also referred to as colored chemicals/substances or pigments. This method is used for experiments, to identify coloring agents and to separate out a compound into its various components.

In thin layer chromatography a stationary phase, silica gel with a glass backing, is dotted on a pencil drawn

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.

The boiling point of a compound is often related to its polarity (see also polarity chapter). The lower the boiling point is, the higher the vapor pressure of the compound and the shorter retention time usually is because the compound will spent more time in the gas phase. That is one of the main reasons why low boiling solvents (i.e., diethyl ether, dichloromethane) are used as solvents to dissolve the sample. The temperature of the column does not have to be above the boiling point because every compound has a non-zero vapor pressure at any given temperature, even solids. That is the reason why we can smell compounds like camphor (0.065 mmHg/25 oC), isoborneol (0.0035 mmHg/25 oC), naphthalene (0.084 mmHg/25 oC), etc. However, their vapor pressures are low compared to liquids (i.e., water (24 mmHg/25 oC), ethyl acetate (95 mmHg/25 oC), diethyl ether (520 mmHg/25 oC)).

For this experiment, the lab was separated into groups of four. Each member of the group

Introduction Thin-layer chromatography, also known as TLC, is a principle that describes how various compounds travel multiple distances when placed as a thin layer on a plate. TLC is a technique that can be used to determine how many components are in a mixture. TLC can also be used to determine a specific compound in a mixture. After performing TLC, the retention factor (Rf) can be used to determine a specific compound in a mixture. The retention factor (Rf) is During TLC, there is a step called elution.

Thin layer chromatography is the separation of substances using different solvents that run up the TLC plate to find different materials and colors in the sample. Three solvents in this test were one hundred percent acetone, one hundred percent isopropyl, and distilled water. In this test we timed the speed of each solvent and recorded the best color content. PACE Introduction Thin Layer Chromatography is a commonly used experiment in forensics, and is the separation of substances using different solvents. What I want to find out is what the fastest solvent is, but keeps the best color on the TLC plate.

This process relies on heating a solution to separate out the different components. This is done through the fact that each compound has a specific inherent boiling point, a temperature at which a liquid turns into a vapor. These vapors are then passed through a fractioning column. These columns are often filled with glass or plastic beads to aid in the separation process by increasing surface area for condensation. As the the vapor moves through the column, the compounds with higher boiling points condense on the column and return to the solution, where as components with lower boiling points move through the column and collect near the

     In liquid chromatography, the separator is called the column and consists in most cases of a tube filled with porous material called the stationary phase. A liquid, called the mobile phase, flows through the tube between the particles of stationary phase material. A liquid sample is taken from a mixture to be analyzed and introduced to a part of the system that is at elevated pressure. The sample is then transported to a separator by the flow in the system.

Liquid chromatography would be best because of the differing polarities of illicit drugs. A stationary phase will be chosen that has a polarity that will bind to each of the different drugs in slightly different affinity