PhD Scientific Days 2023

Pharmaceutical Sciences - Posters F

The study of hysteresis using high performance liquid chromatography on polysaccharide type stationary phases

Text of the abstract

The farmacological properties of enantiomers may differ. With more enantiopure drugs ont he market new, better, faster chiral analitical methods should be developed. A lot chiral HPLC stationary phases are available on the market, most of them are polysaccharide types. In our study 7 of these type of column were tested in polar organic mode (PO) and reversed phase (RP). In PO mode we use neat acetonitrile (ACN), or neat alcohol such as methanol (MeOH), ethanol (EtOH) or 2-propanol (IPA). In PO mode the mixture of the eluents were not yet fully investigated. Németh et al. described the hysteresis phenomena first on polysaccharide stationary phases using MeOH-IPA mobile phase mixtures [1]. The hysteresis phenomena is one where chromatographic parameteres such as selectivity and retention factor are dependent on the preconditioning of the column. As mixtures we investigated MeOH-IPA and some alcohol-ACN mixtures. We used 4 ftalimide and 5 oxazolidinone analouges to study the effect of eluent mixtures and hysteresis on polysaccharide type stationary phases.
Investigating the enantiomers of ketoprofen we could investigate the hysteresis also in reverse phase mode using ACN-water mixtures . This indicates the further use of the hysteresis phenomena in chiral HPLC separations.
Regarding our measurments on amylose type stationary phases eluent mixtures can fine tune the chiral separation, in some cases the use of mistures can change the enantiomeric elution order. This creates new possibilities for chiral HPLC separations. On amylose type columns we investigated the hysteresis phenomena.
We can assume that using eluent mixtures different comformations of the chiral stationary phases have higher stability and that causes the change in enantiorecognition. We may assume that the change of the conformations are due to the change in the H-bonds which fixes the higher order structure of the stationary phase and this change in the secondary bonds are caused by the use of eluent mixtures. It is important to note that we did not investigated the hysteresis phenomena on cellulose type chiral stationary phases.
1. Horváth, S. and G. Németh, G.: J. Chrom. A, 2018. 1568: p. 149-159.