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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 ...
A faster flow rate of the eluent minimizes the time required to run a column and thereby minimizes diffusion, resulting in a better separation. However, the maximum flow rate is limited because a finite time is required for the analyte to equilibrate between the stationary phase and mobile phase, see Van Deemter's equation.
Retardation factor. In chromatography, the retardation factor (R) is the fraction of an analyte in the mobile phase of a chromatographic system. [1] In planar chromatography in particular, the retardation factor RF is defined as the ratio of the distance traveled by the center of a spot to the distance traveled by the solvent front. [2]
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 ...
Bartel Leendert van der Waerden. Jan Jozef van Deemter (31 March 1918 – 10 October 2004) was a Dutch physicist and engineer known for the Van Deemter equation in chromatography. [1] [2] [3] He obtained his doctorate in physics from the University of Amsterdam in June of 1950. Starting in 1947 he began work for Royal Dutch Shell as a ...
Two-dimensional chromatography. Two-dimensional chromatography is a type of chromatographic technique in which the injected sample is separated by passing through two different separation stages. Two different chromatographic columns are connected in sequence, and the effluent from the first system is transferred onto the second column. [1]
The distribution constant (or partition ratio) (K D) is the equilibrium constant for the distribution of an analyte in two immiscible solvents. [1] [2] [3]In chromatography, for a particular solvent, it is equal to the ratio of its molar concentration in the stationary phase to its molar concentration in the mobile phase, also approximating the ratio of the solubility of the solvent in each phase.
Displacement chromatography. Displacement chromatography is a chromatography technique in which a sample is placed onto the head of the column [n 1] and is then displaced by a solute that is more strongly sorbed than the components of the original mixture. The result is that the components are resolved into consecutive "rectangular" zones of ...