Explain Why TLC Is Used To Separate Non-Volatile Mixtures

Introductory Questions Define SPE and explain the role of each of the steps used to prepare the SPE cartridge for the isolation of the analyte. Solid phase extraction (SPE) is an extraction method that uses a liquid and solid phase to isolate a single analyte or a specific type of analyte from a solution. It is usually used to clean up a sample before using a chromatographic or other analytical method to quantify the amount of analyte(s) in the sample.

A thin-layer plate is prepared by coating a glass plate with a thin film of a granular material, usually silica gel or aluminium oxide. This granular material serves as the solid stationary phase and is usually held in place on the plate with a binding agent such as plaster of Paris. If the sample to be analysed is a solid, it must first be dissolved in a suitable solvent and a few microliters of the solution spotted with a capillary tube onto the granular surface near the lower edge of the plate. A liquid sample may be applied directly to the plate in the same manner. The plate is then placed upright into a closed chamber that contains a selected liquid, with care that the liquid does not touch the sample

CER Labs 2-3 Figure 1. Friedel-Crafts Acylation. Claim: An acetyl group was efficiently introduced to ferrocene by Friedel-Crafts Acylation (Figure 1). We isolated our crude yield while comparing 2 purification techniques: column chromatography and recrystallization. TLC, NMR, and IR spectroscopy were used throughout the process to identify ferrocene and acetylferrocene in addition to evaluating the levels of purity.

Introduction: The objective of this experiment was to use a spectrophotometer to calculate the absorbance wavelength for the commercial dyes that were given. Light is composed of tiny particles that are called photons, just like matter is composed of tiny particles called atoms. Using the spectrophotometer you can see that different dyes absorb at different wavelengths. With all of the experimentation done the concentration, absorbance and the max wavelengths should be found. Figure 1: Schematic of a single beam UV spectrophotometer Materials: There was an array of materials needed to complete this experiment.

Introduction Chromatography is the technique of separating of mixtures based on their intermolecular forces. It separates according to their adsorption differences. Intermolecular forces make molecules bind on the solid surfaces; this process is referred to as the absorption. A molecule undergoes desorption process when it moves from the solid surface into the solution. The different rates between desorption and adsorption are applied in the chromatography methods for separation of mixtures.

A titration is the precise addition of a solution from a buret into an accurately measured volume of a sample solution. A titrant is the solution in the buret that is used for the titration, and the volume of the solution is known. The titrants used in this lab were 0.1M hydrochloric acid and 0.1M sodium hydroxide (the reactions can be seen in figure 4). A Bronsted-Lowry acid is a compound that donates a proton. A Bronsted-Lowry base is a compound that accepts a proton.

Photogate sensor is capable in measuring a very accurate speed so we can fix the speed of the rotation by using photogate sensor in our experiment. The sensor has an infrared LED emitter on one arm and a photo transistor on the other arm. As the mass passes the photogate sensor , it will block the infrared beam that is exist between the infrared LED emitter and photogate sensor. The timing of beam blocking will determine the speed of the rotation. It operates based on Pendulum-Timing process where the timing begins when the photogate is first interrupted and the timing continues until it is interrupted for the second time which will result in the period of rotation.

The contact angle of the film was measured with distilled water under room temperature. 2.10 Crosslink density () and average molecular weight between two crosslinks (Mc) Crosslink density () and average molecular weight between two crosslinks (Mc) were determined by the equilibrium swelling method according to the Flory-Rehner equation (Eq. 1). Toluene was chosen as a solvent for the calculations. Mc =-(ƥpVsØ1/3)/(ln(1-Ø)+ Ø+ƛØ2) (1) where Vs is the molar volume of the solvent, ƥp is the density of the polymer and Ø is the volume fraction of the polymer in the swollen state.

Laser provide intense and unidirectional ray of light. Laser light is monochromatic. Wavelength of light is determined by amount of energy released when electron drops to lower orbit. Light is coherent; all the photons have same wave fronts that launch to unison. Laser light has tight beam and is strong and concentrated.

After this light is sufficiently filtered, the remaining ‘wanted’ wavelength of light is projected into a photomultiplier, which is an instrument that can collect, amplify and then finally measure the amount of light that was detected. The detected light is then displayed and compared directly to the calibration curve (on the output device). From this comparison, scientist can relate the light reading detected from the unknown and can then determine the concentration of the solution as absorbance is always proportionately equal to concentration of the metal atoms within the solution. (meaning that the absorbance will always increase relative to higher