Organic acids, electrophoretic mobility

Anions and uncharged analytes tend to spend more time in the buffered solution and as a result their movement relates to this. While these are useful generalizations, various factors contribute to the migration order of the analytes. These include the anionic or cationic nature of the surfactant, the influence of electroendosmosis, the properties of the buffer, the contributions of electrostatic versus hydrophobic interactions and the electrophoretic mobility of the native analyte. In addition, organic modifiers, e.g. methanol, acetonitrile and tetrahydrofuran are used to enhance separations and these increase the affinity of the more hydrophobic analytes for the liquid rather than the micellar phase. The effect of chirality of the analyte on its interaction with the micelles is utilized to separate enantiomers that either are already present in a sample or have been chemically produced. Such pre-capillary derivatization has been used to produce chiral amino acids for capillary electrophoresis. An alternative approach to chiral separations is the incorporation of additives such as cyclodextrins in the buffer solution. 

Only a few systematic studies have been carried out on the mechanism of interaction of organic surfactants and macromolecules. Mishra et al. (12) studied the effect of sulfonates (dodecyl), carboxylic acids (oleic and tridecanoic), and amines (dodecyl and dodecyltrimethyl) on the electrophoretic mobility of hydroxyapatite. Vogel et al. (13) studied the release of phosphate and calcium ions during the adsorption of benzene polycarboxylic acids onto apatite. Jurlaanse et al.(14) also observed a similar release of calcium and phosphate ions during the adsorption of polypeptides on dental enamel. Adsorption of polyphosphonate on hydroxyapatite and the associated release of phosphate ions was investigated by Rawls et al. (15). They found that phosphate ions were released into solution in amounts exceeding the quantity of phosphonate adsorbed. 

CE has been applied in the analysis of organic acids (27). The key parameter in these analyses is electrophoretic mobility, which depends on both molecular structure and separation conditions. Therefore, developing chemometrical models to predict the mobilities of ions will relieve analysts of a large number of costly and time-consuming experiments. Two principal methods based on the quantitative relationship between molecular structures and elec-... 

N. from influenza virus has M, 130,000. Most neuraminic acid-containing proteohormones and some enzymes are inactivated by treatment with N. on the other hand, the electrophoretic mobility of many glycoproteins, e.g. plasma proteins, may be altered after treatment with N., but their activity is unaffected. The N. of influenza virus destroys the protective mucus layer of the attacked organ. 

By plotting electrophoretic mobility versus pH as shown in Fig. 10, the p7 of the synthesized dimer was found to be approximately 4.9. The dimer was incorporated into the running buffer of 0.10 M sodium phosphate buffer (pH adjusted between 4.5 and 7.0) at a concentration of 1 mM and amino acids prepared at 1 mg/mL in methanol. Bonding through the primary amine group, loss of polarity, and an additional ionizable group resulted in poor solubility in aqueous solutions. This required the addition of organic modifiers (4% methanol and 8% DMSO) to the aqueous... 

BIO) carried out starch gel electrophoretic studies in 1200 individual placentas and in extracts of seven different organs obtained at autopsy from 14 individuals. The tissues showed different combinations of one or more bands of four distinct and, in some respects, biochemically different, acid phosphatase components. These were designated as A, B, C, and D in order of decreasing anodal mobilities. For example, in the case of heart tissue one individual showed three bands, ABD, whereas the remaining 13 showed a combination of two bands, BD. With regard to kidney tissue, 13 individuals had a combination of ABD, and one individual had a pair, BD. 

For the sake of comparison, the results of the mechanistic model are also given in Table 14.2. To assess the robustness of the models, a 10-fold cross-validation method was used on all data sets (29). The consistency of the results of cross validation for all groups proved the stability and robustness of the models. Figure 14.6 demonstrates the plot of the CART-ANFIS calculated values for the acid mobilities against the experimental values. The high value of R = 0.970 for this plot indicates that the CART-ANFIS model can be considered as a powerful tool for the prediction of the electrophoretic mobihty of organic and sulfonic... 

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