Modeling of the influence of the modifier concentration on the retention process in NP-HPLC

The adsorption model for an accurate prediction of the analyte retention in the normal - phase liquid chromatography with a binary mobile phase has been proposed. This model was derived using a thermody-namically consistent modified competitive Langmuir isotherm. The performance of the proposed equation was compared with two retention models reported in literature. All models were verified for different NP-LC systems by use of three criteria: the sum of squared differences between the experimental and theoretical data, approximation of the standard deviation and the Fisher test.