PhD Scientific Days 2024

Poster Session B - Pharmaceutical Sciences and Health Technologies 1.

Chemo-and eanatioselective reversed-phase HPLC analysis of dexketoprofen. Fine-tuning enantioselectivity through hysteretic behavior and temperature-dependent enantiomer elution order on polysaccharide chiral stationary phases

Text of the abstract

In the pharmaceutical industry the chiral switch strategy involves the redevelopment of a chiral drug that has already been approved as a racemate, with emphasis on developing and marketing the eutomer. This imposes many challenges on the analytical field. New, fast, environment friendly analytical methods should be developed in the shortest time possible. In the field of chiral analytics high performance liquid chromatography applying a chiral stationary phase is considered the gold standard. However, these HPLC method developments are still working on a trial-and-error way. This requires many expensive chiral columns and the excessive use of toxic mobile phases. Our goal was to achieve the separation of dexketoprofen, R-ketoprofen and some organic impurities of dexketoprofen. After screening the separation capability of four polysaccharide columns (Lux Amylose-1, Lux Amylose-2, Lux Cellulose-1 and Lux Cellulose-2) in polar organic and in reversed-phase modes, appropriate enantioseparation was observed only on the Lux Amylose-2 column in an acidified acetonitrile/water mixture. A full factorial design was used for further method optimization and the ratio of the organic compound in the mobile phase, the column temperature, the amount of acidic additive in the eluent, the flow rate was determined. The optimized chromatographic parameters are as follows, Lux Amylose-2 column, acetonitrile:water:acetic acid 50:50:0.1 (v/v%), 20°C, 1 mL/min flow. Using this method a baseline separation for the two enantiomers and 3 other organic impurities were achieved. The method was then validated according to ICH guidelines to be able to quantify 0.1% impurity. Using the optimized method 3 different commercially available drugs were tested. We studied the various chromatographic effects in details. The change of column temperature from 10 to 55°C resulted in the reversal of enantiomeric elution order. The other phenomena was the hysteresis on the amylose-based selectors, which to date was only observed in polar organic mode. Interestingly an expressed hysteresis was observable using reversed phase eluent mixtures.