Migrating component

The anions, which are not involved in the reaction v = 0, should not move in the steady state [i.e., in Eq. (4.17), J = 0]. This implies that the diffusional component of their flux to the surface should be fully compensated by a migration component away from the surface (Fig. 4.3). 

A chromatogram obtained under the above condition showed that with increasing concentration of ethyl acetate, the composition of migrating components becomes increasingly rich in MA content. Quantitatively speaking, the reference samples with ST mole % higher than 50 to 100 (PST) were characterized by different jRf values from zero to unity. Under this development condition it was also affirmed that the Rf values were almost independent of molecular weight. 

According to (1.3b), the nonconvectional electro-diffusion flux component j. is a superposition of the following two terms. The first is the diffusional Fick s component proportional to the concentration gradient VC. The second is the migrational component, proportional to the product of the ionic concentration Cj and the electric force —ZiFV

proportionality factor. Einstein s equality (1.3c) relates ionic mobility to diffusivity >. ... 

A solution of L-fucose (4.92 g, 30 mmol) in anhydrous DMF (50 mL) was stirred with a desiccant (Drierite or Sikkon, 1 g) at 0°C (ice bath), and 2-methaxypropene (2.16 g, 30 mmol) was added followed by p-toluenesulfonic acid (-20 ing). After 1 h at 0°C, an additional stoichiometric amount of reagent (2.16 g) was added, and stirring was continued for 2 h at 0°C. Sodium carbonate (-5 g) was added, and the mixture was stirred further 1 h at room temperature. The solids were filtered off, and the filtrate was evaporated under diminished pressure at 40°C to a syrup that contained (TLC, ethyl acetate) one major product plus minor, fast-migrating components. Rapid chromatography of the product on a column of silica gel gave pure, crystalline 3,4-O-isopropylidene-L-fucopyranose 31 yield 3.7 g (-60%) mp 110-111°C, [ ]D -90 - -70° (24 h, equil. e 0.2, water). 

Concerning the migration component of the overall flux, in line withEq. (1.136), for a z z electrolyte it is given in terms of charge per area and time as... 

In EK injection, sample introduction is usually biased. However, the sample can be introduced to a microchip in a non-biased manner, as long as the electric voltage was applied for a sufficient time so that the slowest migrating component has passed the intersection and entered the analyte waste channel. Accordingly, the sample composition at the intersection is representative of that in the original sample, though it is not the case somewhere downstream in the waste channel [107,340]. 

Where cF.o is the initial concentration of the migrating component in the simulant. In contrast to Eq. (10-2) the partition coefficient K plays an important role here, where the sorption of component into the polymer is proportional to KPP... 

Figure 2 Schematic illustration of electropherograms typical for the four main modes of CZE listed in Table 1. The conditions are stated on charts a to d for each mode A, arheic CZE B, co-directional CZE C, counterdirectional CZE, when the neutral tracer migrates slower than any of the charged sample components D, counterdirectional CZE with the neutral tracer being the fastest-migrating component.

To increase the speed of ion flow, a relatively large electric field is used (greater than, for example, that used in the CPC method, described below). Under these conditions, we can neglect the diffusion and convection components of current compared to the migration component. Then the density of current j + due to cations with number n, is ... 

Synthesis of /x-chain only was first found in tissue culture lines grown from human lymphoma cells (Tl). The patient later described (B3) is just like a typical case of Bence Jones only myelomatosis, with amyloidosis, except that a fast-migrating component reacting only with anti- was also found. This was not visible on serum electrophoresis. It might just represent a ghost of memory of the IgM type of immunoglobulin the original plasma cell precursor should have made. 

Here too, the distribution was found to occur in a double peak. This is clearly shown by the graph in Fig. 13 where there appears to be a more loosely bound, rapidly migrating component as well as a tightly bound component on the surface of the basalt "fissure." Thus the same effect is seen in two dimensions with basalt that was seen in three dimensions with Los Alamos tuff. 

The relative contributions of diffusion and migration to the flux of a species (and of the flux of that species to the total current) differ at a given time for different locations in solution. Near the electrode, an electroactive substance is, in general, transported by both processes. The flux of an electroactive substance at the electrode surface controls the rate of reaction and, therefore, the faradaic current flowing in the external circuit (see Section 1.3.2). That current can be separated into diffusion and migration currents reflecting the diffusive and migrational components to the flux of the electroactive species at the surface ... 

For many electrochemical systems, the mathematical treatments are simplified if the migrational component to the flux of the electroactive substance is made negligible. We discuss in this section the conditions under which that approximation holds. The topic is discussed in greater depth in references 7-10. 

Detection of the migrating components is important and can be either selective or universal depending upon the detector used. The response of the detector to each component is plotted as an electropherogram. The order of elution in the classic CE set-up is positive... 

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