Explain Why TLC Is Used To Separate Non-Volatile Mixtures

1066 Words5 Pages
TLC is a technique used to separate non-volatile mixtures [188]. It is performed on a sheet of glass, plastic or aluminium foil coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide or cellulose. This layer of adsorbent is known as the stationary phase. After the sample has been applied on the plate, the solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. To quantify the results, the distance traveled by the substance is divided by the total distance traveled by the mobile phase. This ratio is called the retention factor (Rf). TLC can be used to identify the compounds present in a given mixture and determine the purity of a substance. For the accurate quantitative analysis, the…show more content…
An FTIR spectrometer simultaneously collects high spectral resolution data over a wide spectral range. FT-IR spectrometry was developed in order to overcome the limitations encountered with dispersive instruments. A solution was developed which employed a very simple optical device called an interferometer. The interferometer produces a unique type of signal which has all of the infrared frequencies “encoded” into it. The signal can be measured very quickly. The time element per sample is reduced to a matter of a few seconds rather than several minutes. Most interferometers employ a beamsplitter which takes the incoming infrared beam and divides it into two optical beams. One beam reflects off of a flat mirror which is fixed in place. The other beam reflects off of a flat mirror which allows this mirror to move a very short distance (typically a few millimeters) away from the beamsplitter. The two beams reflect off of their respective mirrors and are recombined when they meet back at the beamsplitter. Because the path that one beam travels is a fixed length and the other is constantly changing as its mirror moves, the signal which exits the interferometer as the result of two beams “interfering” with each other. The resulting signal is called an interferogram. As the interferogram is measured, all frequencies are being measured simultaneously. The use of the interferometer results in extremely fast measurements. Because the analyst requires a frequency spectrum (a plot of the intensity at each individual frequency) in order to make identification, the measured interferogram signal cannot be interpreted directly. This can be accomplished via a well-known mathematical technique called the Fourier transformation. This transformation is performed by the computer which presents the user with the desired spectral information for analysis [194]. The instrumental

More about Explain Why TLC Is Used To Separate Non-Volatile Mixtures

Open Document