Influencia de las modificaciones estructurales de redes metal-orgánicas en microextracción

Se han llevado a cabo diferentes estrategias sintéticas para la modificación estructural de redes metal-orgánicas de UiO-66. Los materiales sintetizados se han caracterizado por difracción de rayos X en polvo, adsorción de N2 y dispersión dinámica de la luz. Se ha evaluado la influencia de tales modificaciones estructurales del UiO-66 en lo que respecta a su eficacia como sorbente en extracción en fase sólida dispersiva miniaturizada en combinación con cromatografía líquida de alta resolución y detección de diodos en línea, para un grupo de ocho contaminantes orgánicos de naturaleza variada.Different synthetic strategies were used to evaluate the structure modifications of the metal-organic framework UiO-66. The characterization techniques for the assynthesized materials were powder X-ray diffraction, N2 adsorption, and dynamic light scattering. The influence of those UiO-66 structure modifications was evaluated on its efficiency as sorbent in miniaturized dispersive solid-phase extraction combined with high-performance liquid chromatography and diode array detection for the determination of eight organic pollutants

Metal-Organic Frameworks in Green Analytical Chemistry

Metal-organic frameworks (MOFs) are porous hybrid materials composed of metal ions and organic linkers, characterized by their crystallinity and by the highest known surface areas. MOFs structures present accessible cages, tunnels and modifiable pores, together with adequate mechanical and thermal stability. Their outstanding properties have led to their recognition as revolutionary materials in recent years. Analytical chemistry has also benefited from the potential of MOF applications. MOFs succeed as sorbent materials in extraction and microextraction procedures, as sensors, and as stationary or pseudo-stationary phases in chromatographic systems. To date, around 100 different MOFs form part of those analytical applications. This review intends to give an overview on the use of MOFs in analytical chemistry in recent years (2017–2019) within the framework of green analytical chemistry requirements, with a particular emphasis on possible toxicity issues of neat MOFs and trends to ensure green approaches in their preparation

Evolution and current advances in sorbent-based microextraction configurations

This review overviews the main developments achieved in analytical sample preparation regarding the use of solid sorbents as extractants in different sorbent-based miniaturized, micro-scale and microextraction methods. Two main groups are proposed for the classification of the current approaches, based on their operational mode: micro-solid-phase extraction (µ-SPE) and solid-phase microextraction (SPME), while describing their respective main sub-modes: static- and dispersive-µ-SPE, and SPME with fibers and in tube SPME. Furthermore, other important sorbent-based microscale approaches (e.g., stir bar sorptive extraction, stir cake sorptive extraction, stir bar sorptive-dispersive microextraction, and thin film microextraction, among others) are also considered.MJT-R thanks Spanish Ministry of Science and Innovation, for her Juan de la Cierva – formación contract and Aragon Regional Government and the European Social Fund (E07_20R). IP-F thanks the Canary Agency of Research and Innovation (ACIISI), co-funded by the European Social Fund, for her FPI PhD fellowship. VP thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for the project MAT2017-89207-R.Peer reviewe

Influence of Ligand Functionalization of UiO-66-Based Metal-Organic Frameworks When Used as Sorbents in Dispersive Solid-Phase Analytical Microextraction for Different Aqueous Organic Pollutants

Four metal-organic frameworks (MOFs), specifically UiO-66, UiO-66-NH2, UiO-66-NO2, and MIL-53(Al), were synthesized, characterized, and used as sorbents in a dispersive micro-solid phase extraction (D-µSPE) method for the determination of nine pollutants of different nature, including drugs, phenols, polycyclic aromatic hydrocarbons, and personal care products in environmental waters. The D-µSPE method, using these MOFs as sorbents and in combination with high-performance liquid chromatography (HPLC) and diode-array detection (DAD), was optimized. The optimization study pointed out to UiO-66-NO2 as the best MOF to use in the multi-component determination. Furthermore, the utilization of isoreticular MOFs based on UiO-66 with the same topology but different functional groups, and MIL-53(Al) to compare with, allowed us for the first time to evaluate the influence of such functionalization of the ligand with regards to the efficiency of the D-µSPE-HPLC-DAD method. Optimum conditions included: 20 mg of UiO-66-NO2 MOF in 20 mL of the aqueous sample, 3 min of agitation by vortex and 5 min of centrifugation, followed by the use of only 500 µL of acetonitrile as desorption solvent (once the MOF containing analytes was separated), 5 min of vortex and 5 min of centrifugation. The validation of the D-µSPE-HPLC-DAD method showed limits of detection down to 1.5 ng·L−1, average relative recoveries of 107% for a spiked level of 1.50 µg·L−1, and inter-day precision values with relative standard deviations lower than 14%, for the group of pollutants considered