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Abstract:
Chiral anaesthetics are used in the preponderant majority of clinical surgeries to be progressed under general anaesthesia. These chiral substances are currently applied in racemic mixtures of both enantiomers. Several studies indicated differences in the anaesthetic potential and side actions to human body for the single enantiomers [1]. Hence the development of a separation process for chiral anaesthetics persists a great interest.
To achieve the demanding objective of separating the model anaesthetics Isofluran and Desfluran due to their keen analogy tailor-made glass beads were used for the immobilization of a modified urea bonded γ-Cyclodextrine as reported in [2], forming the base for the intended preparative gas chromatographic separation process.
Initial point for the survey was the synthesis of porous glass beads with full control regarding texture properties, particle size distribution and shaping in a fluidized bed reactor to spherical particles [3]. Alongside physical measurements to investigate the texture properties of the porous glass beads, by mercury intrusion, nitrogen adsorption and microscopic imaging in particular classic chromatographic experiments were used to investigate the characteristic of native glass particles in a gas chromatographic separation process (see Fig. 1). These results led to optimized physical traits of the glass beads, which should be modified for chromatographic separation processes in a next step.
First achievements were made with spherical glass beads featuring different reproducible texture properties. These native glass beads were tested in pulse chromatographic experiments regarding their interactions with Desfluran and Isofluran. The modified γ-Cyclodextrine was immobilized on the most promising samples and completely characterized with all mentioned techniques. The analysis revealed a minor change in texture properties due to selector modification and also the need of further chemical improvement of the surface area of the glass beads. Furthermore, the homogenous dispersion of the selector was approved with IR-microscopy. Based on those results thermodynamic parameters for a modified multi-Langmuir isotherm for both model anaesthetics were estimated. In further studies these data will be used to develop a continues separation process for chiral anaesthetics.
