Determination of thermodynamic quantities of enantioseparation of selected chiral weak acids on Chiralpak IG column and its coated analogue

Author: Mariam Maisuradze
Keywords: Enantioseparation, thermodynamic parameters, reversal of enantiomer elution order, coated, covalently immobilized
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The goal of our research was the calculation of thermodynamic parameters of enantioseparation in high-performance liquid chromatography. This can help to predict the suitable analytical conditions for the given compound on given column and to achieve the desired selectivity and enantiomer elution order. Also we compared thermodynamic parameters of conventionally coated and immobilized columns having the same chiral selector. Analysis were performed at different temperatures and in different mobile phases. For analyzed compounds, the difference in adsorption enthalpy and adsorption entropy were calculated using the plot of natural logarithm of the separation factor versus the reciprocal of the absolute temperature. We studied if the enantioseparation mechanism was controlled by enthalpic or entropic term and what was the influence of temperature on retention and separation. For the experiment several acidic compounds were chosen, particularly arylpropionic acid derivatives, which are nonsteroidal anti-inflammatory drugs (NSIDs). They are used as painkillers and antipyretics. It is important to separate their stereoisomers, as frequently only one enantiomer has pharmacological activity and the other is inactive or even toxic.