Analytical strategies for sample preparation using novel materials

Abstract

Sample preparation is the stage of the analytical procedure that deals with the extraction of the target compounds from a sample and includes the elimination of the interferences coming from the sample matrix, thus ensuring the compatibility with the analytical instrument while improving the selectivity and sensitivity of the entire method. Given the complexity of the samples, the trace concentrations at which analytes are present in the samples, and the importance of incorporating the Green Chemistry principles in the analytical process, the development of microextraction techniques and the incorporation of new materials have been demanding research lines within analytical sample preparation to address these challenges. Among the outstanding materials described that can meet green requirements and exhibit successful analytical performance in sample preparation, ionic liquids (ILs) and metal-organic frameworks (MOFs) must be highlighted. ILs are molten salts formed by the combination of bulky organic cations and organic or inorganic anions. They present melting points lower than 100 °C and, depending on the moieties selected and the incorporation of specific functional groups in their structure, they can exhibit specific characteristics. Therefore, it is possible to prepare several interesting derivatives, such as polymeric ionic liquids (PILs) and IL-based surfactants. MOFs are crystalline materials composed of metallic clusters and organic linkers connected by coordination bonds. They are mainly characterized by their high surface area and tunability, which allows designing MOFs with specific topologies by selecting the adequate components and synthetic conditions. These characteristics make MOFs potential materials to host target compounds. In this Doctoral Thesis, ILs and MOFs were designed, synthesized and incorporated in a wide variety of challenging analytical applications using microextraction techniques. Among the existing techniques, dispersive liquid-liquid microextraction (DLLME) and solid-phase microextraction (SPME) were selected due to their simplicity, fastness, and high preconcentration ability.