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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.
[10]: 280–4 Hence, a single experiment can be used to measure the logarithms of the partition coefficient (log P) giving the distribution of molecules that are primarily neutral in charge, as well as the distribution coefficient (log D) of all forms of the molecule over a pH range, e.g., between 2 and 12.
In chromatography substances are separated by partition between a stationary phase and a mobile phase. The analyte is dissolved in the mobile phase, and passes over the stationary phase. Separation occurs because of differing affinities of the analytes for the stationary phase. A distribution constant, K d can be defined as
Nitrilotriacetic acid is commercially available as the free acid and as the sodium salt. It is produced from ammonia , formaldehyde , and sodium cyanide or hydrogen cyanide . Worldwide capacity is estimated at 100 thousand tonnes per year. [ 6 ]
Chromatographic response function, often abbreviated to CRF, is a coefficient which measures the quality of the separation in the result of a chromatography.. The CRF concept have been created during the development of separation optimization, to compare the quality of many simulated or real chromatographic separations.
In liquid chromatography, the mobile phase velocity is taken as the exit velocity, that is, the ratio of the flow rate in ml/second to the cross-sectional area of the ‘column-exit flow path.’ For a packed column, the cross-sectional area of the column exit flow path is usually taken as 0.6 times the cross-sectional area of the column.
A high-performance countercurrent chromatography system. Countercurrent chromatography (CCC, also counter-current chromatography) is a form of liquid–liquid chromatography that uses a liquid stationary phase that is held in place by inertia of the molecules composing the stationary phase accelerating toward the center of a centrifuge due to centripetal force [1] and is used to separate ...
The distribution coefficient (K c which coincides with partition coefficient) of atabrine varied by the composition of the solvent system and the pH of the buffer. In the next article, Craig was inspired by the work of Martin and Synge with partition chromatography to develop an apparatus that would separate compounds based on their ...