Direct Solid Analysis of Metal-Organic Frameworks Using Laser-Assisted Micro-Pyrolysis and Flowing Atmospheric-Pressure Afterglow High-Resolution Mass Spectrometry

Metal-organic frameworks (MOFs) are highly porous, organic-inorganic hybrid crystalline materials formed by the fusion of metal ions and organic linkers. MOFs are increasingly used in fields like catalysis, energy and gas storage, sensors, drug delivery, and agriculture, to name a few, due to their large surface area, readily available active sites, structural flexibility, high stability, and easy functionalization. Currently, the chemical characterization of MOFs relies on analytical techniques such as XRD, FTIR spectroscopy, and electron microscopy/EDX. However, most methods are not ideal for monitoring MOFs in applications within complex media due to limitations like matrix effects and spectral overlaps, which require significant sample preparation steps to remove the matrix. Owing to rapid growth in MOF applications, this study focuses on devising a novel approach to chemically characterize MOFs, especially for monitoring them when deployed in complex media applications.
FAPA is a plasma-based ambient mass spectrometry (AMS) desorption/ionization source that requires little to no sample preparation and provides information in real time. Plasma-based AMS techniques excel at small molecule analysis but can be limited when it comes to low vapor pressure analytes (large or tightly bound molecules). On the other hand, coupling LAMP with FAPA HRMS has been demonstrated to facilitate the analysis of large molecular weight analytes, including synthetic polymers and biopolymers. This project aims to develop LAMP FAPA HRMS towards direct solid analysis of MOFs. Preliminary results show successful qualitative analysis of solid MOF components. Variation in MOFs structures, adsorbates, and components with respect to the characteristic ions observed will be discussed.