Effect of organic modifier

Fig. 2-14. The effect of organic modifier on retention, selectivity and resolution of methionine on teicoplanin CSP (250 x 4.6 mm). The flow rate was 1.0 mL min at ambient temperature (23 °C).

Table 2-6. The effects of organic modifier on the separation of amino acids on teicoplanin CSP.a ...

Comparison of the Effect of Organic Modifiers on Analytes with log P — 3... 

Figure 4.5 Effect of organic modifier on peptide retention. Synthetic octapeptides of the structure described in Figure 4.1 were separated by gradient elution on an octyl column using aqueous-organic systems containing a constant TFA concentration of 0.1%. (Reproduced from D. Guo, C.T. Mant, A.K. Taneja, J.M.R. Parker, and R.S. Hodges, J. Chro-matogr., 359 499 [1986]. With permission from Elsevier Science.)...

FIGURE 1.6 Effect of organic modifier (methanol) percentage in the elnent on the retention factors (a) and observed enantioselectivities (b) of Af-(2,4-dinitrophenyl)-a-(2-chlorobenzyl)-proline employing an 0-9-[(2,6-diisopropylphenyl)carbamoyl]quinine-based CSP. Experimental conditions Elnent, ammonium acetate buffer-methanol (total ionic strength = 25 mM pHj, = 6.5), methanol content varied between 60 and 90%, while ionic strength and apparent pH were kept constant temperature, 40 C flow rate, 0.8 mLmin . (Reproduced from A. Peter et al., J. Sep. ScL, 26 1125 (2003). With permission.)... 

FIGURE 4 The effect of organic modifier content on retention factor (Ink) in CEC. (Reproduced with permission from reference 13.)... 

A Ahmed, DK Lloyd. Effect of organic modifiers on retention and enantiomeric separations by capillary electrophoresis with human serum albumin as a chiral selector in solution. J Chromatogr A 766 237—244, 1997. 

On the other hand, Bhattacharya et al. have reported the plasticization effect of organically modified layered silicates on dynamic mechanical properties [13]. In this work, nanocomposites of SBR have been prepared using various nanofillers like modified and unmodified montmorillonite, SP, hectorite etc. It has been observed that the Tg shifts to lower temperature in all the nanocomposites, except for systems from hectorite and NA. This is due to the fact that clay layers form capillaries parallel to each other as they become oriented in a particular direction. Due to wall slippage of the unattached polymer through these capillaries, the Tg is lowered, which could be even more in the absence of organo-modifiers [13]. A similar type of plasticization effect is also noted in the case of the low... 

TABLE 3 Effect of Organic Modifiers and Sulfuric Acid on the Chiral Resolution of Leucine and Phenylglycine... 

Figure 5.7 presents a guide to choosing the CSP best fitted to the racemate structure. Optimization strategies for various CSPs, including the effect of organic modifier and eluent pH on enantioselectivity, have been reported [289-2921. 

Nucleosil 100-3-C18 (3 pm) Effect of organic modifier on EOF and retention of solutes... 

Effect of Organic Modifier on Basic Analyte pA Shift... 

M. Salo, H. Vuorela, and J. Halmekoski, Effect of organic modifier on the retention of retinoids in reversed-phase liquid chromatography, Chromatographia 36 (1993), 147-151. 

The effect of organic modifiers. The effect of organic mobile-phase modifiers on retention and stereoselectivity of abscisic acid enantiomers has also been examined using methanol, ethanol, and 2-propanol (91). The results of this study indicate that hydrophobic interactions are involved in the retention, but not the stereochemical resolution of the solutes. Miwa and co-workers (91) have also postulated that hydrophobic and hydrogenbonding interactions are important in the retention of basic compounds. 

Figure 8.19. Four chromatograms illustrating the effect of organic modifier in MPB, showing the selectivity effect of several impurities.

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