thin-layer chromatography

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Related to thin-layer chromatography: immunoassay, paper chromatography, column chromatography


a technique for analysis of chemical substances. The term chromatography literally means color writing, and denotes a method by which the substance to be analyzed is poured into a vertical glass tube containing an adsorbent, the various components of the substance moving through the adsorbent at different rates of speed, according to their degree of attraction to it, and producing bands of color at different levels of the adsorption column. The term has been extended to include other methods utilizing the same principle, although no colors are produced in the column. adj., adj chromatograph´ic.

The mobile phase of chromatography refers to the fluid that carries the mixture of substances in the sample through the adsorptive material. The stationary or adsorbent phase refers to the solid material that takes up the particles of the substance passing through it. Kaolin, alumina, silica, and activated charcoal have been used as adsorbing substances or stationary phases.

Classification of chromatographic techniques tends to be confusing because it may be based on the type of stationary phase, the nature of the adsorptive force, the nature of the mobile phase, or the method by which the mobile phase is introduced.

The technique is a valuable tool for the research biochemist and is readily adaptable to investigations conducted in the clinical laboratory. For example, chromatography is used to detect and identify in body fluids certain sugars and amino acids associated with inborn errors of metabolism.
adsorption chromatography that in which the stationary phase is an adsorbent.
affinity chromatography that based on a highly specific biologic interaction such as that between antigen and antibody, enzyme and substrate, or receptor and ligand. Any of these substances, covalently linked to an insoluble support or immobilized in a gel, may serve as the sorbent allowing the interacting substance to be isolated from relatively impure samples; often a 1000-fold purification can be achieved in one step.
column chromatography the technique in which the various solutes of a solution are allowed to travel down a column, the individual components being adsorbed by the stationary phase. The most strongly adsorbed component will remain near the top of the column; the other components will pass to positions farther and farther down the column according to their affinity for the adsorbent. If the individual components are naturally colored, they will form a series of colored bands or zones.

Column chromatography has been employed to separate vitamins, steroids, hormones, and alkaloids and to determine the amounts of these substances in samples of body fluids.
exclusion chromatography that in which the stationary phase is a gel having a closely controlled pore size. Molecules are separated based on molecular size and shape, smaller molecules being temporarily retained in the pores.
gas chromatography a type of automated chromatography in which the mobile phase is an inert gas. Volatile components of the sample are separated in the column and measured by a detector. The method has been applied in the clinical laboratory to separate and quantify steroids, barbiturates, and lipids.
gas-liquid chromatography gas chromatography in which the substances to be separated are moved by an inert gas along a tube filled with a finely divided inert solid coated with a nonvolatile oil; each component migrates at a rate determined by its solubility in oil and its vapor pressure.
gel-filtration chromatography (gel-permeation chromatography) exclusion chromatography.
ion exchange chromatography that utilizing ion exchange resins, to which are coupled either cations or anions that will exchange with other cations or anions in the material passed through their meshwork.
molecular sieve chromatography exclusion chromatography.
paper chromatography a form of chromatography in which a sheet of blotting paper, usually filter paper, is substituted for the adsorption column. After separation of the components as a consequence of their differential migratory velocities, they are stained to make the chromatogram visible. In the clinical laboratory, paper chromatography is employed to detect and identify sugars and amino acids.
partition chromatography a process of separation of solutes utilizing the partition of the solutes between two liquid phases, namely the original solvent and the film of solvent on the adsorption column.
thin-layer chromatography that in which the stationary phase is a thin layer of an adsorbent such as silica gel coated on a flat plate. It is otherwise similar to paper chromatography.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

thin-lay·er chro·ma·tog·ra·phy (TLC),

chromatography through a thin layer of cellulose or similar inert material supported on a glass or plastic plate.
Farlex Partner Medical Dictionary © Farlex 2012

thin-lay·er chro·ma·tog·ra·phy

(TLC) (thin-lā'ĕr krō'mă-tog'ră-fē)
The investigative modality applied through a thin layer of cellulose or similar inert material supported on a glass or plastic plate.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

thin-layer chromatography (TLC)

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Weins, "Theoretical Basis of Thin Layer Chromatography (TLC)," in Quantitative Thin-Layer Chromatography, pp.
Antioxidant screening using thin-layer chromatography Figure 1 shows that hexane-ethanol solvent system exhibited more separation when hexane is in larger amount.
O'Donnell, "Direct analysis of thin-layer chromatography spots by diffuse reflectance Fourier transform infrared spectrometry," Analytical Chemistry, vol.
Jakobs, "Thin-layer chromatography of active compounds from ointments and suppositories followed by direct quantitative analysis by remission," Journal of Chromatog raphy, vol.
Influence of diet on detection of fecal bile acids by thin-layer chromatography. Journal of Wildlife Management, 58:295-299.
The primary instrumental techniques commonly involved in the analysis of bank dye-pack chemicals (i.e., thin-layer chromatography and GC-MS) are widely used not only in forensic laboratories but also in analytical laboratories from various areas of scientific industries (e.g., pharmaceutical, environmental).
When samples make it to the laboratory, one of the oldest and most versatile screening techniques is TLC: thin-layer chromatography. Many of us first experienced thin-layer chromatography in junior-high-school science labs.
Thin-layer chromatography (TLC) is used to monitor the progress of the reaction.
Fat characterisation: Saponification value: Iodine value; Free fatty acid value: Peroxide value: Thin-layer chromatography separation of simple lipids.
Using a gas chromatography-electron capture detector (GC-ECD), a GC-mass spectrometer (GC-MS), GC-microconductivity, thin-layer chromatography, ultraviolet-spot in situ scanning spectrum, and element analysis, we identified PC[B.sub.3] and PC[B.sub.5] as close to Aroclor 1242 and Aroclor 1254, respectively (Wang et al.
Thin-layer chromatography can also be employed to detect saturated hydrocarbons.
The oil-condition monitor can be used in the petroleum and dairy industries as well as for environmental applications...Chemists at SINTEF Applied Chemistry in Norway have formulated a process that combines synthesis, separation, analysis and screening onto a thin-layer chromatography plate that can make entire combinatorial libraries of compounds ready for biological screening in record times...Chemists from Purdue University have designed a Near Infrared Raman Imaging Microscope that uses Raman spectroscopy to analyze the chemical components of a sample in fractions of a second...Using single particles of light to trap atoms, California Institute of Technology researchers have created the atom-cavity microscope, the first microscope ever to show the motion of a single atom...