In modern analytical chemistry researchers pursue novel materials to meet analytical challenges such as improvements in sensitivity, selectivity, and detection limit. Metal–organic frameworks (MOFs) are an emerging class of microporous materials, and their unusual properties such as high surface area, good thermal stability, uniform structured nanoscale cavities, and the availability of in-pore functionality and outer-surface modification are attractive for diverse analytical applications. This Account summarizes our research on the analytical applications of MOFs ranging from sampling to chromatographic separation.MOFs have been either directly used or engineered to meet the demands of various analytical applications. Bulk MOFs with microsized crystals are convenient sorbents for direct application to in-field sampling and solid-phase extraction. Quartz tubes packed with MOF-5 have shown excellent stability, adsorption efficiency, and reproducibility for in-field sampling and trapping of atmospheric form...

Metal–Organic Frameworks for Analytical Chemistry: From Sample Collection to Chromatographic Separation

A metal organic framework (MOF) represents a new class of hybrid material built from metal ions with well-defined coordination geometry and organic bridging ligands Over the past few years, MOFs have attracted a great deal of attention due to their intriguing framework architecture, topology, and optical properties MOFs have provided promising perspectives in various research fields, such as catalysis, energy storage, drug-delivery systems, non-linear optics, and gas storage Recently, the application of MOFs was further extended to cover new, interesting fields of sensing toward various target components, including small molecules, solvents, pesticides, explosives, and biological markers In this review, we focus on recent progress achieved in MOF research with respect to general sensing principles and analytical performance This review also discusses future industrial applications in sensing that are of immense research interest

Metal organic frameworks for sensing applications

Magnetic solid-phase extraction (MSPE) is a useful sample preparation technique, enabling the dispersion of solid sorbents in liquid sample matrices followed by the magnetic retrieval of the sorbent. MSPE can be implemented using any kind of magnetic materials independently of their size and shape, and is a powerful tool for the application of micro/nanomaterials for analytical sample preparation. Metal-organic frameworks (MOFs) have emerged recently as highly valuable sorbents for solid-phase extraction (SPE) due to their large surface area, chemical selectivity, and versatility for tuning their chemical composition and pore size. For MSPE applications, MOFs can be magnetized, or used as precursors for the preparation of MOF-derived magnetic porous carbons (MPCs). In this review, we outline and discuss the different approaches for the preparation of magnetic MOFs and their conversion to MPCs. The applications of magnetic MOFs and MPCs as sorbents for MSPE are critically discussed and oriented to the type of MOF used and the extracted analytes. Recent efforts on the automation of MSPE procedures using magnetic MOFs and MPCs are also described.

Magnetic solid-phase extraction using metal-organic frameworks (MOFs) and their derived carbons

Recent advancements in sensing techniques based on functional materials for organophosphate pesticides.

Application of nanomaterials in sample preparation

The metal–organic framework ∞[(La0.9Eu0.1)2(DPA)3(H2O)3] was tested for extraction of pyrimicarb, procymidone, malathion, methyl parathion and α- and β-endosulfan from lettuce, with analysis using GC/MS in SIM mode. Experiments were carried out in triplicate at two fortification levels (0.1 and 0.5 mg/kg), and resulted in recoveries in the range of 78–107%, with RSD values between 1.6 and 8.0% for ∞[(La0.9Eu0.1)2(DPA)3(H2O)3] sorbent. Detection and quantification limits ranged from 0.02 to 0.05 mg/kg and from 0.05 to 0.10 mg/kg, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.05–10.0 μg/mL), with correlation coefficients ranging from 0.9990 to 0.9997. Comparison between ∞[(La0.9Eu0.1)2(DPA)3(H2O)3] and conventional sorbent (silica gel) showed better performance of the ∞[(La0.9Eu0.1)2(DPA)3(H2O)3] polymeric sorbent for all pesticides tested.

Potential of a metal–organic framework as a new material for solid‐phase extraction of pesticides from lettuce (Lactuca sativa), with analysis by gas chromatography‐mass spectrometry

An extraction method based on matrix solid-phase dispersion was developed to determine pirimicarb, methyl parathion, malathion, procymidone, α -endosulfan and β -endosulfan in lettuce using gas chromatography-mass spectrometry. The best results were obtained using 4.0 g of lettuce, 2.0 g of silica as dispersant sorbent, 0.1 g of activated carbon as clean up sorbent and acetonitrile as eluting solvent. The method was validated using lettuce samples fortified with pesticides at six different concentration levels (0.1 to 2.0 mg/kg). Average recoveries (7 replicates) ranged from 50 to 120 %, with relative standard deviations between 0.6 and 8.0 %. Detection and quantification limits for lettuce ranged from 0.01 to 0.02 mg/kg and 0.04 to 0.10 mg/kg, respectively.

Rogério Luiz da Silva

Papers

Potential of a metal–organic framework as a new material for solid‐phase extraction of pesticides from lettuce (Lactuca sativa), with analysis by gas chromatography‐mass spectrometry

Multiresidue determination of carbamate, organochlorine, organophosphorus, and dicarboximide pesticides in lettuce by GC/MS.