Trends of microextraction methods for opioids in complex samples

The growing global opioid crisis, evidenced by a 90% surge in overdose deaths between 2013 and 2017 and >130 fatalities reported daily in the U.S., underscores the pressing need for advanced detection methods. Opioids, including natural alkaloids (e.g., morphine), semi-synthetic derivatives (e.g., oxycodone), and synthetic analogs (e.g., fentanyl), pose significant public health risks due to their rampant misuse. This review highlights cutting-edge microextraction technologies, specifically liquid-phase microextraction (LPME) and solid-phase microextraction (SPME), which aim to effectively address these limitations. Recent innovations in LPME include surfactant-assisted single-drop microextraction and hollow fiber LPME with amine-functionalized mesoporous foam. These techniques achieve high recovery rates while significantly minimizing solvent use. Furthermore, deep eutectic solvents and ionic liquids (e.g., [C₈MIM][PF₆]) have emerged as environmentally friendly alternatives, enhancing selectivity and enrichment factors. For SPME, advancements such as molecularly imprinted polymers and graphene oxide nanosheets offer exceptional specificity and reusability, with high recoveries. Novel materials, such as electrochemically co-deposited sol-gel/Cu nanocomposite fibers and magnetic materials, further enhance operational efficiency and reduce processing time. These developments enhance analytical precision and adhere to the principles of green chemistry, facilitating scalable and high-throughput detection of opioids in complex matrices. Future research should focus on integrating these technologies with portable analytical platforms for practical applications. Thin-film microextraction devices can be directly coupled with handheld mass spectrometers or miniaturized GC-MS systems. This integration enables rapid, on-site detection of opioids in forensic or clinical settings. Moreover, microextraction sorbents could be incorporated into paper-based lateral flow assay devices, allowing simple, cost-effective, and disposable field testing for opioid residues.