Analyte solvation-desolvation equilibrium

The analyte solvation-desolvation equilibrium inside the column could be written in the following form ... 

Assuming that solvation-desolvation equilibrium is fast, we can express the overall retention factor of injected analyte as a sum of the retention factor of solvated form multiplied by the solvated fraction (9) and the retention factor of the desolvated form multiplied by the desolvated fraction (1-9), or... 

Expression (4-36) shows that the solvated fraction of the analyte is dependent on the counteranion concentration and desolvation equilibrium parameter. 

Chaotropic Model. If the counteranion concentration is low, some analyte molecules have a disrupted solvation shell, and some do not due to the limited amount of counteranions present at any instant within the mobile phase. If we assume an existence of the equilibrium between solvated and desolvated analyte molecules and counteranions, this mechanism could be described mathematically [151]. 

This equation has three parameters ks is a limiting retention factor for solvated analyte, k s is a limiting retention factor for desolvated analyte, and K is a desolvation parameter [151], The description of the experimental results with function (4-39) is shown in Figure 4-50. Expression (4-39) in principle allows for the calculation of the solvation equilibrium constant from experimental chromatographic data. 

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See also in sourсe #XX -- [ ]

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