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Thin-layer chromatography. Thin-layer chromatography (TLC) is a chromatography technique that separates components in non-volatile mixtures. [1] It is performed on a TLC plate made up of a non-reactive solid coated with a thin layer of adsorbent material. [2] This is called the stationary phase. [2] The sample is deposited on the plate, which ...
The mobile phase is dependent on the absorptivity of the stationary phase and the composition of the compound of interest. [5] The compound is first tested with solutions such as diethyl ether , ethanol , dichloromethane , chloroform for normal phase HPTLC, or solutions such as methanol , acetonitrile , and tetrahydrofuran for reverse phase HPTLC.
Chromatography – a physical method of separation that distributes components to separate between two phases, one stationary (stationary phase), the other (the mobile phase) moving in a definite direction. Eluent (sometimes spelled eluant) – the solvent or solvent fixure used in elution chromatography and is synonymous with mobile phase.
The mobile phase composition does not have to remain constant. A separation in which the mobile phase composition is changed during the separation process is described as a gradient elution. [38] [39] For example, a gradient can start at 10% methanol in water, and end at 90% methanol in water after 20 minutes.
Reversed-phase liquid chromatography (RP-LC) is a mode of liquid chromatography in which non-polar stationary phase and polar mobile phases are used for the separation of organic compounds. [1][2][3] The vast majority of separations and analyses using high-performance liquid chromatography (HPLC) in recent years are done using the reversed ...
The eluent is optimized in small scale pretests, often using thin layer chromatography (TLC) with the same stationary phase, using solvents of different polarity until a suitable solvent system is found. Common mobile phase solvents, in order of increasing polarity, include hexane, dichloromethane, ethyl acetate, acetone, and methanol. [3]
The van Deemter equation in chromatography, named for Jan van Deemter, relates the variance per unit length of a separation column to the linear mobile phase velocity by considering physical, kinetic, and thermodynamic properties of a separation. [1] These properties include pathways within the column, diffusion (axial and longitudinal), and ...
The mobile phase strength is varied from a weak eluent composition to a stronger one. Based on linear solvent strength theory (LSST) of gradient elution for reversed phase chromatography, the relationship between retention time, instrumental variables and solute parameters is shown below. [18] t R =t 0 +t D + t 0 /b*ln(b*(k 0-t d /t 0) + 1)