Kohlrausch regulating function and other conservation laws in electrophoresis

Abstract

The Kohlrausch regulating function (KRF) is a conservation law (conservation function), which is held in electrophoresis and which enables calculation of the so-called adjusted concentrations of constituents. The KRF is not the only conservation function and, depending on the complexity of the electrophoretic system, other conservation laws may be obeyed having a broader range of applicability. The conservation laws are tightly related to system eigenmobilities and system zones (system peaks). In principle, no system eigenmobility is exactly zero, but in most practical cases at least one system's eigenmobility is close to zero. The existence of the close-to-zero eigenmobility inherently points to the existence of a conservation function and a system zone which is stationary. The stationary system zone is called injection zone, stagnant zone, water peak, or solvent dip. Electrophoretic (electromigration) systems can be divided into two types: (i) conservation systems, in which the absolute value of at least one system eigenmobility is close to zero and where at least one conservation law is obeyed and (ii) nonconservation systems, where no system eigenmobility is close to zero and no conservation law is obeyed. The paper reviews work dealing with conservation functions in electromigration, derives some "historical" conservation functions in a new way, derives several conservation functions for systems of multivalent electrolytes, and discusses electrophoretic systems that have nonconservation behavior. In some typical instances, the conservation functions are simulated by means of a dynamic simulation tool and depicted graphically.

Dynamic computer simulations of electrophoresis: A versatile research and teaching tool

“…The simulation data reveal buffer, pH and conductivity changes at the locations of the two migrating samples, at the location of the initial sample pulse (demarcated by dotted lines) and on the cathodic side of the initial sample pulse. The regulating function at the location of the sampling compartment (1.0503 Vsmol/m 5 ) is shown to have a different value compared with that on either side (0.9917 Vsmol/m 5 ) and its gradients after 4 min of current flow are somewhat broader than those of the original buffer distribution (demarcated by the vertical dotted lines) [122][123][124]. No change is predicted at the locations of the migrating samples.…”

“…A total of six (total of nÀ1 with n being the number of ampholytes) migrating boundaries are initially formed on both sides, a stage in which 2nÀ1 zones are present as is shown for the 0.4 min time point [163]. [124]) and electric field strength (E) profiles. The two inserts depict the small omega value deviations across the two boundaries bracketing the mixed sample zone.…”

“…They output the current density, resistance or voltage and the net flow (GENTRANS only) as functions of time. The distributions of the electric field strength can be calculated from the current density and conductivity data and the profiles of the electrophoretic regulating functions can be determined with the concentration and mobility data [123,124].…”

“…The various zone properties for the 0. 9B) and at the stationary, diffusing boundaries at the locations of the initial boundaries between the sample and the buffers (marked with vertical dotted lines) [2,3,123,124]. Once the mixed sample zone has left the sampling compartment (around 0.3 min), the aniline and b-alanine zones at its rear side become adjusted to the omega value of the leader when migrating across the location of the original cathodic boundary between sample and leader (at 2 cm; see 0.3 and 0.4 min time points of panel A).…”

“…progressively broadening) electrophoretic boundaries that are produced between strong and weak electrolytes upon current flow [2,3,46,64,126,127,139] (for examples see Figs. 4-6 and 8-12), was used to discover and understand new types of migrating boundaries [140][141][142][143], provided insight into the regulation principles associated with current flow [2,3,46,123,124,127,144] , which is a strong acid with a mobility equal to that of the buffer additive and which was sampled together with the neutral analytes. S and I refer to the anionically migrating system peak and the location of the initial sample compartment, respectively.…”