Desenvolvimento de uma fase estacionária baseada na imobilização de um polímero fluorado sobre sílica aluminizada para separação de compostos polares

Abstract

Nowadays, liquid chromatography is the most comprehensive analytical technique for the quantification of organic compounds. However, their analyzes produce a large volume of toxic residues due to the use of highly organic mobile phase, especially for polar compounds. Furthermore, polar compounds show poor retention in traditional stationary phases, C8 or C18 chemically bonded, restricting some applications of liquid chromatography. An alternative to overcome these limitations has been the use of immobilized pre-synthesized polymers on an inorganic support, resulting in a finely adjusted selectivity according to the polymer structure, in addition to higher chemical stability. The preparation of moderately polar stationary phases using water-rich mobile phases for the separation of polar compounds has been the object of studies by different researchers. In this work, we prepared stationary phases by self-immobilization of poly(methyl-3,3,3-trifluoropropylsiloxane) (PMTFS) on an aluminized silica support. The stationary phases were self-immobilized for 180 days and were periodically chromatographically analyzed. In this study, the retention properties and the polymeraluminized silica interaction were evaluated for the useful and stable stationary phase preparation. Physicochemical characterizations indicated that the SiAl(PMTFS) particles were spherical and free of agglomerations even after the incorporation of alumina particles and the self-immobilization of PMTFS. The immobilization of PMTFS on aluminized silica support was confirmed by infrared spectroscopy through signals attributed to the stretching C-F bonds between 1210 and 1449 cm-1. SiAl(PMTFS) phase showed high stability under alkaline conditions using a lab-made protocol, which can be associated with the aluminized silica support. The chromatographic characterization of the SiAl(PMTFS) phase was performed by the separation of test mixtures using consolidated protocols. These separations confirmed that the SiAl(PMTFS) phase acts in a reversed-phase mode but requiring water-rich mobile phases for the separation of polar compounds. Therefore, the SiAl(PMTFS) phase presents good chemical stability and also presents the potential to separate polar compounds, generating less toxic organic residues.