Caracterització de sistemes de partició cromatogràfics per a la subrogació de procesos de biopartició

Resumen

The determination of biological properties usually implies expensive and complex procedures which sometimes require the use of living beings, a practice ethically questionable. Thus, the use of physicochemical systems that emulate biopartitioning processes would allow the estimation of biological properties in a faster and automated way avoiding in vivo testing. In the present work, chromatographic and biopartitioning systems characterized in previous works through a same model (the solvation parameter model (SPM)) have been compiled, adding the new developed and characterized systems in the present study. Then, all the systems have been compared using the normalized coeficients resulting from their characterization through the SPM. Finally, correlations between the biological property of interest and the logarithm of the retention factor determined in the best surrogating chromatographic system have been established. The results have shown that toxicity to aquatic species, skin partition, and the octanol-water partition systems can be surrogated employing chromatographic systems based on reserved-phase liquid chromatography and electrokinetic chromatography. Moreover, since there is a lack of studies regarding ionizable solutes, the feasibility of this methodology to estimate biopartitioning properties for ionized compounds have also been evaluated. Particularly, in the present work, the estimation of the octanol-water distribution coefficient of ionized acid-base substances has been studied. With this aim, retention factor-pH profiles have been established for a set of monoprotic acids and bases. To obtain accurate retention factors, the surfactant used to prepare the microemulsion and the ionized solute have the same charge, and a viscosity correction factor has been used. Then, the retention factor of acid-base compounds has been correlated to log Po/w at several degrees of ionization. Results point out that accurate estimations of the parameter can be achieved up to a 99% of ionization. Finally, in order to look for new chromatographic systems presenting different selectivities from those reported to the present, an in-house styrene-co-divinylbenzene monolithic capillary column has been developed and characterized for the separation of a mixture of proteins by ion-pairing gradient reversed-phase liquid chromatography.