Effects of Buffer

Antonenko et al. [540] considered pH gradients forming in the UWL under bulk solution iso-pH conditions. They elegantly expanded on the buffer effect model and made it more general by considering multicomponent buffer mixtures. Direct measurements of the pH gradients (using wire-coated micro-pH electrodes) near the membrane-water interface were described. 

A 10 mM ionic strength universal buffer mixture, consisting of Good zwitterio-nic buffers, [174] and other components (but free of phosphate and boric acid), is used in the pION apparatus [116,556], The 5-pKa mixture produces a linear response to the addition of base titrant in the pH 3-10 interval, as indicated in Fig. 7.53. The robotic system uses the universal buffer solution for all applications, automatically adjusting the pH with the addition of a standardized KOH solution. The robotic system uses a built-in titrator to standardize the pH mapping operation. 

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TABLE 4.4 Effect of Buffer Composition on Mass Recovery of Proteins from TSK-GEL G3000SW< ... 

Rej. R. and Vanderlinde, R. E. Effects of buffers on asperate aminotransferase activity and association of the enzyme with pyridoxal phosphate. Clin. Chem. (1975), 21, 1585-1591. 

The chemistry of hydrothermal solutions from midoceanic ridges has been reasonably explained by the effect of buffering by alteration minerals (Seyfried, 1987 Bemdt et al., 1989). Therefore, it might be worth explaining the chemical composition of hydrothermal solutions from back-arc basins in terms of chemical equilibrium between hydrothermal solutions and alteration minerals. 

Grossman, R D., Wilson, K. J., Petrie, G., and Lauer, H. H., Effect of buffer pH and peptide composition on the selectivity of peptide separations by capillary zone electrophoresis, Anal. Biochem., 173, 265, 1988. 

In preformulation one task is to establish the stability of the drug substance in both solid and dissolved state. In the latter case it is important, with small samples of drug substance, to assess (a) the effect of buffer type, (b) the effect of buffer concentration, (c) the effect of pH in a practical range, (d) the effect of temperature, and (e) the kinetic salt effect. 

G. M. Phillips and B. T. Palermo, Physical form as a determinant of effect of buffered acetylsalicylate... 

KG Mooney, MA Mintun, KJ Himmelstein, VJ Stella. Dissolution kinetics of carboxylic acids II Effect of buffers. J Pharm Sci 70 22-32, 1981. 

AK Mitra, TJ Mikkelson. (1982). Ophthalmic solution buffer systems. I. The effect of buffer concentration on the ocular absorption of pilocarpine. Int J Pharm 10 219-229. 

TABLE 14.4 Effect of Buffer Formulation the on Recovery of Protein from FFPE Lysozyme Tissue Surrogates... 

Specific-ion electrodes are expensive, temperamental and seem to have a depressingly short life when exposed to aqueous surfactants. They are also not sensitive to some mechanistically interesting ions. Other methods do not have these shortcomings, but they too are not applicable to all ions. Most workers have followed the approach developed by Romsted who noted that counterions bind specifically to ionic micelles, and that qualitatively the binding parallels that to ion exchange resins (Romsted 1977, 1984). In considering the development of Romsted s ideas it will be useful to note that many micellar reactions involving hydrophilic ions are carried out in solutions which contain a mixture of anions for example, there will be the chemically inert counterion of the surfactant plus the added reactive ion. Competition between these ions for the micelle is of key importance and merits detailed consideration. In some cases the solution also contains buffers and the effect of buffer ions has to be considered (Quina et al., 1980). 

Table 1. Effect of buffer concentration c on thickness of the electrical double layer 6 [33]...

Figure 3. Effect of buffer concentration on aldrin epoxidation by midge homogenate (mean of 2 experiments)...

Levis KA, Lane ME and Corrigan OI (2003) Effect of Buffer Media Composition on the Solubility and Effective Permeability Coefficient of Ibuprofen. Int J Pharm 253 pp 49-59. 

Manipulation of buffer pH or use of additives can easily vary separation selectivity. In contrast to gel electrophoresis, a single capillary can be used to evaluate the effect of buffer composition or pH on resolution. In CZE the capillary is simply filled with a fresh electrolyte of the chosen composition between analyses. 

Some aspirin products are sold in buffered form. Infer the reasoning behind this practice. Is there clinical evidence to support it To find out, go to the web site above and click on Web Links. Conduct further research to investigate whether there is more recent evidence either in support of or disproving the effectiveness of buffering aspirin. 

Williamson, D.H. Knighton, W.B. Grimsrud, E.P. Effect of Buffer Gas Alterations on the Thermal Electron Attachment and Detachment Reactions of Azu-lene by Pulsed High Pressure Mass Spectrometry. Int. J. Mass Spectrom. 2000, 795/796,481-489. 

Effects of buffer composition on electroosmotic flow in capillary electrophoresis. /. Microcol. Sep. 2, 176-180. 

FIGURE 32 Effects of buffer salt concentration. (Note Baseline deflections as indicated by the arrows.)... 

Fig. 10.1 Effect of buffer composition on the ESI-FTICR-MS spectrum of myoglobin. The spectrum in (a) was acquired from a solution containing 2 pM myoglobin in 50% MeOH, 49% H2O, and 1% HOAc. Peaks corresponding to apomyoglobin and free heme dominate the spectrum. The spectrum in (b) was acquired from a solution...

Several AFM studies examined the effect of buffer conditions on the formation of motifs with DNA molecules. For instance, it has been foimd that the multivalent cations induce the condensation of DNA molecules into higher ordered structures, including toroids and rods [122], More specifically, Zn and Mg ions induce the formation of DNA kinked and perfect circles, respectively [123] (Fig. 16). Also, higher concentrations of spermidine induce the formation of complex flower-shaped structures with single crossover points [122] and increased concentrations of ethanol lead to complex and looped structures [ 124] (Fig. 17). 

The Henderson-Hasselbalch equation may be employed in calculations relating to the properties and effects of buffer solutions (see Box 4.8). 

The rate of a general acid-catalyzed reaction is equal to 2ha ha[HA] multiplied by some function of the substrate concentration(s) where [HA] is the general acid concentration and A ha is the corresponding catalytic rate constant. Experimentally, general acid catalysis can be distinguished from specihc acid catalysis by analysis of the effect of buffer concentration on the overall reaction rate. See also Specific Acid Catalysis Catalysis General Base Catalysis... 

Experimentally, general base catalysis can be distinguished from specific base catalysis by analysis of the effect of buffer concentration on the overall reaction rate. See also Specific Base Catalysis Catalysis General Acid Catalysis... 

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