COLUMN AND THIN LAYER CHROMATOGRAPHY
Maria Janine B. Abarientos, Kuia B. Allarde, Aliana Keshia P. Andino Mary Viadelle E. Andrada and Nina Marian Robelea G. Ang
Organic Chemistry Laboratory
In this experiment, the techniques column and thin layer chromatography was used to separate and determine the purity of the colored components of siling labuyo and malunggay leaves. The results obtained relied on differential solubilities and adsorptivities of the components to be separated with respect to the mobile and stationary phases, wherein the stationary phase/s are silica gel and silica gel G, while the mobile phase/s are the extracts on different solvent system.
This experiment aims to make the students capable of separating the colored components of siling labuyo and malunggay leaves using column chromatography. Determine the purity of the components using the thin layer chromatography (TLC). Measure the Rf values of the colored components in TLC.
Chromatography is the most orient laboratory technique that deals with separation of homogenous and free of interferences mixtures and identification of compounds. Also, it is essential for analyzing complex compounds. The said method is separated into two phases namely stationary and mobile; it is based on differential partitioning. The mobile phase carries the solutes through the stationary phase. This can be either liquid or gas. The stationary phase is the part of the chromatographic system though which the mobile phase flows. This can be either solid or liquid that may be immobilized or absorbed on a solid. There are various types of chromatography – solid-liquid (column, thin layer), liquid-liquid (paper, high-performance liquid), and gas-liquid (vapor-phase) methods. Results may vary on the speed rate of constituents, which can be measured through the Rf values. Chromatography may be classified as preparative or analytical. Preparative Chromatography resembles purification and often for further usage. While Analytical Chromatography, it usually deals with smaller amounts of constituents and relative proportions of analytes measuring.
Column Chromatography is a method in which the stationary bed is within a tube. It is normally used as a purification technique for it isolates desired compounds from a mixture. Analyzing mixtures through this method is applied to the top of the column. The liquid solvent or the eluent is passed through the column with air pressure or by gravity. Equilibrium is achieved between the solute adsorbed on the adsorbent and the eluting solvent flowing down through the column. Various components have different reactivity rates within the stationary and mobile phase hence resulting to different degrees of separation. The distinctive eluates may be collected as soon as the solvent drips through the column. Column chromatography is divided into two categories depending on the flowing movement of the solvent through the column. It is classified as Gravity Column Chromatography, when the solvent flow down in the tube and it is caused by gravity or it is called percolation. If the solvent flowed through an outside force or positive air pressure then it is called flash chromatography. Thin Layer Chromatography (TLC) is a well-oriented and not costly technique, which is used for purity purposes of synthesized compounds and for the indication of extent progress of the reactions involved in the constituents. In this method, a small amount of a solution of the mixture is placed on a TLC plate with a thin layer of silica gel or alumina covered on a plastic sheet and this constitutes the stationary phase. The said sheet shall be deposited in a small amount containing solvent chamber, which is the mobile phase. The capillary tubes serve as the solvent path to move up and also determine the rate of deposited substances. Each deposited component has a different distance moved and seems to...
References: Bayquen A. et.al.(2009).Laboratory Manual in Organic Chemistry.Quezon City: C&E Publishing Inc.do.edu/hndbksupport/ochemlabtech.html 2003
Chemistry http://www.wpi.edu/Academics/Depts/Chemistry/Courses/General/tlc.html AUG 31 2011
Chromatography http://en.wikipedia.org/wiki/Chromatography AUG 31 2011
Chromatography http://www.chemguide.co.uk/analysis/chromatography.html AUG 31 2011
TLC (Thin Layer Chromatography) http://orgchem.colorado.edu/hndbksupport/TLC/TLC.html AUG 31 2011
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