Glossary Of HPLC-LC Separation Terms – K

The listing should be helpful to those just starting in HPLC but it also can serve as a refresher for long-time users in the field.

K

k: See retention factor.

k:' An old term that has been replaced by the IUPAC-approved term, retention factor (k).

K: See partition coefficient.

k _A/B : See selectivity coefficient.

K _c : See distribution constant (coefficient).

Kieselguhr: A diatomaceous earth used in column chromatography and also as a sample cleanup media. Only weakly adsorptive, it can be used as a support in liquid–liquid chromatography. Rarely used in HPLC.

Kinetic plot: Kinetic plots are methods to characterize the practical limits of column performance, where theoretical plates (H) and separation impedance (E) are plotted as a function of the pressure-drop limited plate number (N). The kinetic plot retains the information shown in van Deemter plots but completes it with the information on the bed permeability. See Poppe plot .

Knox equation: A modification of the van Deemter equation developed by John Knox in which the A term that represents eddy dispersion multiplied by u¼, where u is the interstitial eluent velocity. Usually written in terms of the dimensionless or reduced plate height (h) and reduced velocity (ν) as h = Aν¼ + B/ν + Cν. See also van Deemter equation.