Otimização das condições de imobilização de poli(glicidoximetilsiloxano) sobre silica no preparo de fase estacionária polar para CLAE

Abstract

Despite the wide field of application, liquid chromatography without reverse phase mode presents limitations in the division of some classes of compounds, especially the highly polar ones, by branch of low retention in conventional stationary phases, such as C8 and C18 chemically bonded. Aiming to circumvent this limitation, this work presents the development of a stationary phase with polar characteristics to obtain a selective polar material. The stationary phase was prepared from the thermal immobilization of the poly(glycidoxypropylmethylsiloxane), PGPMS, onto silica particles, where the glycidyloxy group provided as desired characteristics for the material. A preparation of the Si stationary phase (PGPMS) was optimized using a factorial design and characterized physicochemically and chromatographically. Compatibility with results of the physical-chemical characterization obtained by infrared spectroscopy, 29Si nuclear magnetic resonance and elemental analysis, was designed to determine: (i) a presence of the PGPMS in the phase through characteristic bands in the infrared spectrum, which the was even quantified by elemental analysis in terms of %C and that PGPMS was chemically immobilized on the silanol silanol groups. A morphological characterization was performed by scanning electron microscopy and porous surface area analysis, showing the silica support immobilized with the polymer maintained as pore characteristics and high surface area in the form of spherical particles of the silica support. The heat treatment of PGPMS on silica was optimized, resulting in optimum temperature and immobilization times of 90°C for 12 h, respectively, in terms of the amount of immobilized polymer as well as the performance of separation. As chromatographic analyzes performed from the separation of standard testers mixtures resulted in typical separations of the reversed phase modality with good stability of the polymer layer on the silica, keeping them fixed as retention property of the products after the continuous use of the material in the separation of the mixtures. In the study of the Si phase retention good (PGPMS), background observations, safety measures, safety measures, guarantees of the presence of the glycidyloxy group, may be suitable for separating mixtures of content that are not normally retained in stationary phases reverse.