Electrophoretic mobility sample preparation

Electrokinetic Measurements. Electrophoretic mobilities were measured with a flat-cell apparatus manufactured by Rank Brothers, Cambridge, England. In addition, several mobility values were checked for accuracy with a Zeta Meter, New York. Mobilities were determined with a small volume of the suspension (approximately 25 cc) that had been prepared for the adsorption experiments. The pH of the solution was measured prior to determining the electrophoretic mobilities, which involved measuring the velocities of five to ten particles in each direction. An average value of the mobilities was recorded. Samples containing the flocculated particles were dipped into an ultrasonic bath for approximately one second prior to making the pH and mobility measurements. 

Choosing an internal standard to correct errors due to sample preparation and injection reduced the impact of variability on the final trueness and precision of the developed method. Peak area can be corrected (peak area/migration time) to avoid the migration time drift influence, because of the temperature affecting both electro-osmosis and electrophoretic mobilities as well as buffer electrolysis, adsorption into the capillary wall and so on. 

Experimental. Samples for electrophoretic mobility (EM) measurements were prepared as previously described for the titration experiments except that violent mixing with destruction of carbon agglomerates was desirable here and was promoted with a 5-10 minute treatment of the capped serum bottles in an ultrasonic bath. The indicator was, of course, deleted in the EM sample preparation procedure. Following mixing, a few drops of the mixture was transferred to a 25 ml flask of benzene and given another ultrasonic treatment. This procedure produced a fairly stable colloid suspension of the carbon black which was used to fill the glass-Teflon commercially available EM cell manufactured by Zeta-Meter, Inc. 

In principle, field-enhanced stacking is a technique for the concentration of charged analytes using discontinuous solutions in the capillary. Neutral analytes are not concentrated by this method because they do not have electrophoretic mobility. However, by utilizing charged micelles, an apparent electrophoretic mobility can be imparted to a neutral analyte according to the principles of MEKC. As in conventional field-enhanced sample stacking, sample solutions are prepared in a... 

Introductory conditions for initial MEKC separations of neutral or weakly ionizable analytes are provided in Table 3.1 [4]. The choice of the running solution is rather arbitrary, but a weakly alkaline borate buffer is recommended because the electrophoretic mobility of the borate ion is rather low and, thus, the current can be kept low. The sample solution can be prepared in any solvents provided... 

Debye layer on the analyte backbone, and the frictional force from the surrounding fluid. Therefore, it is not a trivial matter to determine or calculate the electrophoretic mobility of a given protein/peptide a priori from the sequence information. Also, electrophoretic mobilities of many proteins among a given proteome can be similar. Therefore, the CZE is not an ideal technique for separating a very complex protein mixture for sample preparation purposes. 

Gel electrophoresis requires very small sample sizes and can, in theory at least, give complete separation of a mixture of substances. While it cannot be used to determine electrophoretic mobilities, it allows for the separation and identification of components that would be extremely difficult or impossible to separate using other techniques. It is especially applicable to biological systems where sample availability may be a problem. It may even be used as a small-scale preparative procedure. 

Heat Mn(N03)2 with Cr(N03)3 or NH4VO3 such that the atom percent of dopant is around 0.1. Follow the same procedure as above for the preparation of pMn02. Use a fine fraction of the doped samples to measure the electrophoretic mobility at different... 

Electrokinehc measurements [20] are used to access the electrophoretic mobility /tg of the polymer particles and thereby to get information on their charges. Because of the relahvely small parhcle size of 100 to 250 nm, the measurement technique used for polymer dispersions is laser Doppler electrophoresis. Sample preparation and experimental set-up correspond to those of a dynamic light scattering experiment (Sect 3.2.2, Fig. 3-6). The only difference is a pair of electrodes immersed in the sample between which the particles are moved backwards and forwards by an al-ternahng voltage. 

---