Temperature dependence of Separation of Ketoprofen enantiomers using amylose tris(3,5-dimethylphenylcarbamate) coated on silica gel as stationary phase in High-Performance Liquid Chromatography

Author: Giorgi Kobidze
Keywords: Enantiomers, Thermodinamic parameters, temperature influence
Annotation:

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 at the same stationary phase with 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. In order to calculate termodinamic parameters this experiment was conducted on different temperature. As the results of this study have shown temperature significantly affects chiral recognition pattern of polysaccharide phenylcarbamates. The question is if the change of chiral recognition pattern is caused by any chemical or structural change in the chiral selector, chiral analyte, both of them or is the results of enthalpy-entropy compensation. In order to get some idea on this regard, the enantioseparation of ketoprofen was recorded on Lux Amylose-1 column in the temperature range 10-70°C when increasing the column temperature with 5° increments and afterwards, when cooling the same column with the same increments down to 10°C. 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.