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Adsorption isotherms; Liquid chromatography; Nonlinear frequency response; Harmonic analysis; Higher-order frequency response functions; Numerical analysis
Abstract:
A method for determination of single solute adsorption isotherms based on the analysis of the nonlinear frequency response of a chromatographic column is developed theoretically. In order to demonstrate this method, the frequency response of a chromatographic column is simulated for the periodical inlet concentration changes (sine waveform) around several steady-state concentrations. The frequency response functions (FRFs) up to the third order are calculated from the inlet and outlet concentration changes, which are analyzed using the fast Fourier transform. Afterwards the coefficients of an adsorption isotherm are estimated from the low frequency asymptotes of the FRFs and their derivatives. The obtained coefficients compare well with those used for simulations. Also discussed are some aspects that might affect the accuracy of the suggested method when it is applied to the analysis of experimental data, e.g. influence of velocity fluctuations, noise and size of the analyzed data sample.
Copyright © 2007 Elsevier Ltd. All rights reserved. [accessed 2013 November 26th]
