Study of the thermodynamics and mass transfer kinetics of two enantiomers on a polymeric imprinted stationary phase

The adsorption isotherms of

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- and

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-phenylalanine anilide (PA) on an

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-phenylalanine anilide imprinted stationary phase have been determined using staircase frontal analysis. An aqueous buffer–organic solvent mixture has been used as mobile phase. The measurements were done at temperatures of 40, 50, 60 and 70°C for sample concentrations ranging between 5·10⁻⁴ to 1 g/l. It was found that the adsorption data fit well to both the Freundlich and the Bi-Langmuir isotherm models. Examination of the best values of the numerical coefficients of the Bi-Langmuir model shows that the site class representing the binding sites with the highest binding energy exhibits a very low saturation capacity for the non-imprinted enantiomer, indicating a high selectivity for the imprinted

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-enantiomer. The low energy site class also shows some selectivity for the

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-enantiomer. Mass transfer rate coefficients were obtained for each single breakthrough curve by using the transport model of chromatography. It was found that the mass transfer coefficient of

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-PA increases very rapidly with the sample concentration while there is only a slight increase for the other enantiomer.