Characterization electrophoretic mobility

Rowell and co-workers [62-64] have developed an electrophoretic fingerprint to uniquely characterize the properties of charged colloidal particles. They present contour diagrams of the electrophoretic mobility as a function of the suspension pH and specific conductance, pX. These fingerprints illustrate anomalies and specific characteristics of the charged colloidal surface. A more sophisticated electroacoustic measurement provides the particle size distribution and potential in a polydisperse suspension. Not limited to dilute suspensions, in this experiment, one characterizes the sonic waves generated by the motion of particles in an alternating electric field. O Brien and co-workers have an excellent review of this technique [65]. 

Surface active electrolytes produce charged micelles whose effective charge can be measured by electrophoretic mobility [117,156]. The net charge is lower than the degree of aggregation, however, since some of the counterions remain associated with the micelle, presumably as part of a Stem layer (see Section V-3) [157]. Combination of self-diffusion with electrophoretic mobility measurements indicates that a typical micelle of a univalent surfactant contains about 1(X) monomer units and carries a net charge of 50-70. Additional colloidal characterization techniques are applicable to micelles such as ultrafiltration [158]. 

Although the theory of polyelectrolyte dynamics reviewed here provides approximate crossover formulas for the experimentally measured diffusion coefficients, electrophoretic mobility, and viscosity, the validity of the formulas remains to be established. In spite of the success of one unifying conceptual framework to provide valid asymptotic results, in qualitative agreement with experimental facts, it is desirable to establish quantitative validity. This requires (a) gathering of experimental data on well-characterized polyelectrolyte solutions and (b) obtaining the relationships between the various transport coefficients. Such data are not currently available, and experiments of this type are out of fashion. In addition to these experimental challenges, there are many theoretical issues that need further elaboration. A few of these are the following ... 

Outer-sphere adsorption of Pb(ll)EDTA on goethite. Geochim. Cosmochim. Acta 63(19/20) 2957-2969 Bargar, J.R. Reitmeyer, R. Davis, J.A. (1999) Spectroscopic confirmation of uranium(Vl)-carbonato adsorption complexes on hematite. Environ. Sci. Techn. 33 2481-2483 Bargar, J.R. Reitmeyer, R. Lenhart, J.J. Davis, J.A. (2000) Characterization of U(Vl)-car-bonato ternary complexes on hematite EX-AFS and electrophoretic mobility measurements. Geochim. Cosmochim. Acta 64 ... 

CAE employing antibodies or antibody-related substances is currently referred to as immunoaf-hnity capillary electrophoresis (lACE), and is emerging as a powerful tool for the identification and characterization of biomolecules found in low abundance in complex matrices that can be used as biomarkers, which are essential for pharmaceutical and clinical research [166]. Besides the heterogeneous mode utilizing immobilized antibodies as described above, lACE can be performed in homogeneous format where both the analyte and the antibody are in a liquid phase. Two different approaches are available competitive and noncompetitive immunoassay. The noncompetitive immunoassay is performed by incubating the sample with a known excess of a labeled antibody prior to the separation by CE. The labeled antibodies that are bound to the analyte (the immuno-complex) are then separated from the nonbound labeled antibody on the basis of their different electrophoretic mobility. The quantification of the analyte is then performed on the basis of the peak area of the nonbonded antibody. 

The choice of the FFF technique dictates which physicochemical parameters of the analyte govern its retention in the channel FIFFF separates solely by size, SdFFF by both size and density, ThFFF by size and chanical composition, and EIFFF by mass and charge. The dependence of retention on factors other than size can be advantageous in some applications, and different information can be obtained by employing different techniques in combination or in sequence. On the other hand, the properties that can be characterized by FFF include analyte mass, density, volume, diffusion coefficient, charge, electrophoretic mobility, p/ (isoelectric point), molecular weight, and particle diameter. 

Bargar, J. R., Reitmeyer, R Lenhart, J. J. Davis, J. A. 2000. Characterization of U(VI)-carbonato ternary complexes on hematite EXAFS and electrophoretic mobility measurements. Geochimica et Cosmochimica Acta, 64, 2737- 2749. 

Several of the minor proteins of the MFGM have been isolated and partially characterized (Keenan and Dylewski, 1995). A systematic nomenclature has not been developed for the MFGM proteins and most are referred to by their relative electrophoretic mobility on SDS-PAGE and whether or not they are glycoproteins. The proteins of the MFGM represent approximately 1 % of the total proteins in milk. 

The physicochemical characterization of complexes formed between plasmid DNA and products 2 and 3 demonstrates a different behaviour of the new lipid/ DNA complexes, compared to previously described cationic lipids that classically compact DNA and retard DNA in gel electrophoresis. The different nature of the complexes, and especially the unperturbed electrophoretical mobility we have observed, propose them as potential self-assembling systems for gene delivery (Scherman et al., 2001). 

We have tried to specify the influence of different physico-chemical parameters upon the electrophoretic mobility, using model particles such as silica (Aerosil 380 - Degussa) which is characterized by a charge very close to that of natural suspended sediment from Loire and Gironde. 

Characterization of the Polystyrene Latex Samples. The polystyrene, PS, latex samples under investigation were characterized according to particle size, concentration of surface sulphates and electrophoretic mobility, em, in deionized water. The results, Table I, show that all the samples were of similar size with the exception that the Dow latexes were monodisperse while... 

About 20% of the X-chromosomes in American Blacks contain A+. It has about the same enzymatic activity as B+ but has higher electrophoretic mobility because aspartate replaces asparagine due to a A— > G mutation at nucleotide (nt) 376 (65). The G-6-PD deficiency typical of Blacks is A— this has always one amino acid substitution in addition to the mutation which characterizes A+. The most common second mutation in A— is G— > A at nt 202. However, there may be mutations at nt 680 or nt 968 instead. Thus, at the molecular level, there are three A- variants instead of one. On the other hand, a few separately recorded variants were at first erroneously thought to be distinct from A-. In any case, all African deficiency variants are descendants of A+ (66). 

One approach to this problem would be to isolate the intact lectin-receptor molecules from the cell membranes and characterize them. Work in this direction has been initiated in our laboratory, and a method for the isolation of the peanut agglutinin receptor from membranes of neuraminidase-treated human erythrocytes on a column of peanut agglutinin-polyacryl-hydrazido-Sepharose has been developed (21). The amino acid composition, D-glucosamine ancHg-galac-tosamine content, and the electrophoretic mobility on polyacrylamide gel electrophoresis in sodium... 

The movement (migration) of a charged species under the influence of an applied field is characterized by its electrophoretic mobility, fie, which has units of cm2 sec 1 V 1. Mobility is dependent not only on the charge density of the solute (the overall valence and size of the solute molecule), but also on the dielectric constant and viscosity of the electrolyte. Mobility is also strongly dependent on temperature, increasing by approximately 2% for each Kelvin rise in temperature.2 In the presence of electroosmotic flow (Section 4.3.3), the apparent mobility is the sum of the electrophoretic mobility of the analyte, /ze, and the mobility of the electroosmotic flow, /XGO. 

ELECTROPHORETIC MOBILITY The movement of charged particles or molecules (e.g., proteins) when they are placed in an electric field in electrophoresis electrophoresis can be used to separate molecules on the basis of slight differences in charge and is therefore used in the identification and characterization of mutant proteins. 

The distortions induced in the DNA double helix by the interstrand cross-links have been characterized by several techniques. As judged by chemical probes (diethyl pyrocarbonate, hydroxylamine, osmium tetroxide), antibodies to cisplatin-modified poly(dG-dC)-poly(dG-dC), natural (DNase I) and artificial (1,10-phenanthroline-copper complex) nucleases, the cytosine residues are accessible to the solvent, and the distortions are located at the level of the adduct [48-50]. From the electrophoretic mobility of the multimers of double-stranded oligonucleotides containing a single interstrand cross-link [50] it is deduced that the DNA double helix is unwound (79°) and its axis is bent (45°). 

Increased voltage (and the associated gain in electrical field strength E) increases ion migration velocity U and thus separation speed (providing 0 does not increase too severely as a side effect). For many purposes, it is useful to have a convenient parameter to characterize migration velocities independent of E. The electrophoretic mobility p fulfills this role it is defined by... 

Electrophoresis makes use of differences in the electrophoretic mobility of electrically charged particles (biomolecules, micro-organisms etc.) as a means to separate them. For this purpose, a homogeneous, rectified electrical field is used. Thanks to the excellent resolution and mild operating conditions, this is currently the best analytical method for protein separation, purification and characterization. It is also used as a preparative separation method which allows a few grams per hour to be purified. 

Zeta potential was the first, experimentally available value characterizing edl. The potential of the solid particles in the electrolyte solutions may be determined on the basis of one of the four following phenomena microelectrophoresis, streaming potential, sedimentation potential and electroosmosis. The most popular of them and the best described theoretically and methodically is the electrophoresis. Other papers, concerning the electrophoretic mobility, stationary level determination and the theory of the charged particles transportation in the electric field are still published. 

The various latexes were characterized with respect to particle size and size distribution, surface charge and functional group density, and electrophoretic mobility behavior. As observed by transmission electron microscopy all latexes were found highly monodisperse with a uniformity ratio between 1.001 and 1.010, a property due to the short duration of the nucleation period involved in the various radical-initiated heterogeneous polymerization processes. The surface charge density was determined by a colorimetric titration method reported elsewhere [13]. 

To characterize a surface electrokinetically involves the measurement of one of the above electrokinetic effects. With disperse colloidal systems it is practical to measure the particle electrophoretic mobility (induced particle velocity per unit applied electric field strength). However, for a nondisperse system one must measure either an induced streaming potential or an electro-osmosis fluid flow about the surface. 

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