Applications of metal organic frameworks in dispersive micro solid phase extraction (D-μ-SPE)

Metal-organic frameworks (MOFs) are a fascinating family of crystalline porous materials made up of metal clusters and organic linkers. In comparison with other porous materials, MOFs have unique characteristics including high surface area, homogeneous open cavities, and permanent high porosity with variable shapes and sizes. For these reasons, MOFs have recently been explored as sorbents in sample preparation by solid-phase extraction (SPE). However, SPE requires large amounts of sorbents and suffers from limited contact surfaces with analytes, which compromises extraction recovery and efficiency. Dispersive SPE (D-SPE) overcomes these limitations by dispersing the sorbents into the sample, which in turn increases contact with the analytes. Miniaturization of the microextraction procedure, particularly the amount of sorbent reduces the amount consumed of the organic solvent and shorten the time required to attain the equilibrium state. This may explain the reported high efficiency and applicability of MOFs in dispersive micro SPE (D-µ-SPE). This method retains all the advantages of solid phase extraction while also being simpler, faster, cheaper, and, in some cases, more effective in comparison with D-SPE. Besides, D-µ-SPE requires smaller amounts of the sorbents which reduces the overall cost, and the amount of waste generated from the analytical process. In this review, we discuss the applications of MOFs in D-µ-SPE of various analytes including pharmaceuticals, pesticides, organic dyes from miscellaneous matrices including water samples, biological samples and food samples.

Potential Utility of Metal-Organic Framework-Based Platform for Sensing Pesticides

The progress in modern agricultural practices could not have been realized without the large-scale contribution of assorted pesticides (e.g., organophosphates and nonorganophosphates). Precise tracking of these chemicals has become very important for safeguarding the environment and food resources owing to their very high toxicity. Hence, the development of sensitive and convenient sensors for the on-site detection of pesticides is imperative to overcome practical limitations encountered in conventional methodologies, which require skilled manpower at the expense of high cost and low portability. In this regard, the role of novel, advanced functional materials such as metal-organic frameworks (MOFs) has drawn great interest as an alternative for conventional sensory systems because of their numerous advantages over other nanomaterials. This review was organized to address the recent advances in applications of MOFs for sensing various pesticides because of their tailorable optical and electrical characteristics. It also provides in-depth comparison of the performance of MOFs with other nanomaterial sensing platforms. Further, we discuss the present challenges (e.g., potential bias due to instability under certain conditions, variations in the diffusion rate of the pesticide, chemical interferences, and the precise measurement of luminesce quenching) in developing robust and sensitive sensors by using tailored porosity, functionalities, and better framework stability.

Mg2+ incorporated Co-based MOF precursors for hierarchical CNT-containing porous carbons with ORR activity

The light and abundant Mg²⁺ was introduced as a heteroatom into a Co-MOF to synthesize a series of Mg-Co bimetallic MOFs, further acting as excellent precursors for hierarchically CNTs-containing nanoporous carbons.