Principles of Multidimensional Liquid Chromatography as Applied to Polymer Analysis

2 PRINCIPLES OF MULTIDIMENSIONAL LIQUID CHROMATOGRAPHY AS APPLIED TO POLYMER ANALYSIS 

Every chromatographic process is controlled by the equilibrium distribution of the solute between the mobile and stationary phases. The retention volume V describing the volume of mobile phase that is required to elute the analyte from the column, is given by Equation 17.4  

AG is always negative, and the decrease in free energy can be due to adsorption effects (change in AH) or entropic interactions (change in AS). AS is always operating when the polymer chain cannot occupy all possible conformations in a pore (confined space) due to the limited size of the pore relative to the size of the macromolecule. In a real 

In an ideal SEC experiment, enthalpic effects are not operating (AH = 0) and, thus, AEac equals 1. Accordingly, the distribution coefficient of ideal SEC is only a function of AS, and Kd is given by Equation 17.7  

In a real LC system, the distribution coefficient is a function of the entropic and enthalpic terms. Therefore, the retention volume is described by Equation 17.8 (Pasch and Trathnigg, 1998)  

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