Crystalline MOF nanofilm-based SALDI-MS array for determination of small molecules.

A highly oriented crystalline metal-organic framework (MOF) nanofilm array was prepared and used for surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) for determination of small molecules. The MOF nanofilm was characterized using scanning/transmission electron microscopy, X-ray diffraction, and ultraviolet-visible spectroscopy. Different small molecules (anthracene, n-eicosanoic acid, Rhodamine B) were successfully determined by this MOF nanofilm array with limits of detection (LOD) between 0.1-5 ng·mL-1 and limits of quantification (LOQ) between 1 and 10 ng·mL-1. Compared to previously reported MOF-based SALDI-MS, this array exhibits better reproducibility (3.3-5.2%) and recovery (89-105%). The intensity of the MS peak remains the same after 25 repeated cycles. This indicates good repeatability. This MOF nanofilm-based SALDI-MS array can be used for determination of fatty acid and Rhodamine B in real samples with good recovery (83-106%). Graphical abstract Schematic representation of the principle of crystalline MOFs nanofilm-based SALDI-MS array.