A Dual Approach Combining Metal-Organic Frameworks and Commercial Solid-Phase Microextraction Coatings for Monitoring Volatiles in Passion Fruit.

Abstract

This study presents the applicability of a solid-phase microextraction (SPME) coating based on the CIM-80(Al) metal-organic framework (MOF), prepared by in situ solvothermal growth onto braided silver wires, for the untargeted analysis of passion fruit juices. After the characterization of the MOF-coated fiber by Fourier-transform infrared spectroscopy, scanning electron microscopy, and powder X-ray diffraction, it was applied in both headspace (HS)- and direct immersion (DI)- SPME in combination with gas chromatography-mass spectrometry. The studies were carried out in comparison with three commercial SPME fibers. Considering all the fibers studied, up to 52 and 26 compounds were tentatively identified via HS- and DI-SPME, respectively. Besides, all fibers presented adequate reproducibility and similar lifetime, even in the DI mode and despite the sample complexity. In HS-SPME, a total of 25 compounds were tentatively identified with the MOF-coated fiber. From these analytes, 10 compounds (∼42%) were exclusively detected with the MOF-coated fiber. In DI-SPME, 10 compounds were tentatively identified with the MOF-coated fiber, and four of these compounds (∼50%) were exclusively detected with this fiber. Overall, the results indicate that the MOF-coated fiber offers a superior selectivity for heavier, less volatile, and less polar analytes, therefore acting as a complementary tool for commercial coatings when intending metabolomic studies for food analysis. The dual approach with MOF-coated fiber and commercial SPME coatings provides more comprehensive information for food analysis.