Phosphate buffer ionic strength effect

FIGURE 8 Effect of buffer (ionic) strength on enantioresolution of (a) enantiomers of C6H5C0NHCHRC02H, where R is ( ) -CH2OH, ( ) -CH3 and ( ) -CH3 on the BSA-based CSP, (b) iV-benzoyl alanine on BSA-based CSP, and (c) ketoprofen on avidin CSP with phosphate buffer as the main component of the mobile phases in all of the studies. (From Refs. 28, 32, and 70.)... 

Hemolysis in hypotonic phosphate buffer pH and ionic strength effects Hemolysis in low ionic strength alkaline buffer density gradient centrifugation Homogenization gradient centrifugation... 

Figure 6.9 Effect of CITREM concentration on the molecular and thermodynamic parameters of complex protein-surfactant nanoparticles in aqueous medium (phosphate buffer, pH = 7.2, ionic strength = 0.05 M 20 °C) (a) extent of protein association, k = Mwcomplex/Mwprotem (b) structure-sensitive parameter, p (c) second virial coefficient, A2 (rnolal scale) (d) effective charge, ZE (net number n of moles of negative charges per mole of original sodium caseinate nanoparticles existing at pH = 7.2 (Mw = 4xl06 Da)). The indicated cmc value refers to the pure CITREM solution. Reproduced from Semenova et al. (2007) with permission.

FIGURE 11 The effects of phosphate buffer concentration (ionic strength) on the chiral resolution of (a) rf-ephedrine ( ), /-ephedrine ( ), (/-norephedrine ( ), and /-norephedrine (O) and (b) the dansyl amino acids aspartic acid (A), glutamic acid (O), serine ( ), and phenylalanine (V) on /1-CD columns. (From Refs. 65,70.)... 

The concentration of buffer is also a very important aspect in the optimization of the chiral resolution on these CSPs. It has been reported that an increase in buffer concentration caused a decrease in the retention and selectivity for all amino acids except for the basic amino acids. Therefore, the separation of basic amino acids is possible only with the most concentrated buffers. The buffers of concentrations in the 25-50-mM range were used for the chiral resolutions with some exceptions. In spite of this, few reports are available for the optimization of the chiral resolution by varying the ionic strength of the mobile phase. The effect of ionic strength of phosphate buffer on the chiral resolution of serine was carried out by Gubitz and Jellen [18] and the best resolution was achieved at 0.01 M concentration (Fig. 7). In another study, the concentration of ammonium acetate (0.001-0.01 M) was varied to optimize the chiral resolution of amino acids [19]. The effect of the concentration of ammonium acetate on the chiral resolution of amino... 

Figure 5.2 Effect of ionic strength on the separation of bioactive peptides. Conditions capillary, 375 gm O.D. X 75 /u.m I.D. x 57 cm (50 cm to detector) separation voltage, 30 kV temperature, 30°C buffer, 0.025 M-0.125 M sodium dihydrogen phosphate, pH 2.44. (Reprinted from Ref. 5 with permission.) (1) Bradykinin (BRAD) (2) Angiotensin II(ANG II) (3) Thyrotropin releasing hormone (TRH) (4) Luteinizing hormone releasing hormone (LHRH) (5) Bombesin (BOMB) (6) Leucine enkephalin (LENK) (7) Methionine enkephalin (MENK) (8) Oxytocin (OXYT) (9) Dynorphin (DYNO).

Fig. 14.32. Cyclic voltammogram of coenzyme Q within the bilayer electrode. Phosphate buffer (pH 7.4, ionic strength 0.15), scan rate =100 mV/s. (Reprinted from Y. Xiaoling, J. Cullson, S. Sun and F. M. Hawkridge, Interfacial Electron Transfer Reactions of heme Proteins, Charge and Field Effects in Biosystems, M. J. Allen, S. F. Cleary, and F. M. Hawkridge, eds., vol. 2, p. 87, Plenum, 1989.)...

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