UiO-66 Metal-Organic Framework-Coated Solid-Phase Microextraction Fiber Coupled with GC–MS for Rapid Trace Determination of Methyl Tert-Butyl Ether

Trace determination of methyl tert-butyl ether (MTBE) is difficult when only small sample volumes are available because this analyte is volatile and can be strongly affected by matrix components during sample preparation. Here, UiO-66-coated solid-phase microextraction (SPME) fibers were prepared on stainless-steel wires using a polydimethylsiloxane (PDMS)-assisted coating procedure and applied to headspace SPME coupled with gas chromatography-mass spectrometry (GC-MS). Five metal–organic frameworks were evaluated under the same extraction conditions. Among them, UiO-66 gave the strongest response for MTBE and produced 2.0–4.4-fold higher peak-area responses than the tested commercial fibers under identical HS-SPME–GC-MS conditions. Density functional theory (DFT) calculations gave the most negative adsorption energy for the UiO-66–MTBE system, supporting the experimental trend. After optimization, the method was linear from 24.4 to 1480 μg/L, with a concentration-based limit of detection of 7.4 μg/L and an absolute amount of 0.074 ng for a 10 μL sample. The relative standard deviation was no higher than 5.45%, and the relative error was within 9.46%. Recoveries in spiked water and soil samples were 86.5%–110.9%. These results indicate that UiO-66-coated SPME fibers can serve as rapid, durable, and efficient extraction devices for trace MTBE analysis.