Home | | Modern Analytical Chemistry | Optimizing Chromatographic Separations Using Column Selectivity to Optimize Resolution

Chapter: Modern Analytical Chemistry: Chromatographic and Electrophoretic Methods

Optimizing Chromatographic Separations Using Column Selectivity to Optimize Resolution

A second approach to improving resolution is to adjust alpha, α. In fact, when α is nearly 1, it usually is not possible to improve resolution by adjusting kB’ or N.

Using Column Selectivity to Optimize Resolution

A second approach to improving resolution is to adjust alpha, α. In fact, when α is nearly 1, it usually is not possible to improve resolution by adjusting kB’ or N. Changes in α often have a more dramatic effect on resolution than kB’. For example, changing α from 1.1 to 1.5 improves resolution by 267%.

A change in α is possible if chromatographic conditions are altered in a man- ner that is more selective for one of the solutes. If a solute participates in a sec- ondary equilibrium reaction in either the stationary or mobile phase, then it may be possible to alter that phase in a way that selectively changes the solute’s capacity fac- tor. For example, Figure 12.13a shows how the pH of an aqueous mobile phase can be used to control the retention times, and thus the capacity factors, for two substi- tuted benzoic acids. The resulting change in α is shown in Figure 12.13b. In gas chromatography, adjustments in α are usually accomplished by changing the sta- tionary phase, whereas changing the composition of the mobile phase is used in liq- uid chromatography.


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
Modern Analytical Chemistry: Chromatographic and Electrophoretic Methods : Optimizing Chromatographic Separations Using Column Selectivity to Optimize Resolution |

Related Topics

Modern Analytical Chemistry: Chromatographic and Electrophoretic Methods


Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.