Technological advancements and challenges in the analysis of fluoroquinolone antibiotic environmental residues

Fluoroquinolone antibiotics (FQs) are widely used broad-spectrum antimicrobials, and their incomplete metabolism and continuous discharge have led to their frequent detection in surface water, groundwater, wastewater, and aquaculture systems. Although generally present at ng/L-μg/L levels, environmental FQ residues may affect microbial communities, aquatic organisms, and the spread of antimicrobial resistance. Accurate determination of FQs in environmental waters remains challenging because dissolved organic matter, humic substances, metal ions, proteins, surfactants, and suspended particles can influence analyte extraction, recognition, and signal generation. This review summarizes recent advances in analytical approaches for FQs determination, with emphasis on three key stages of the analytical process: molecular recognition, target enrichment, and signal transduction. Conventional chromatographic methods, especially LC-MS/MS, are discussed together with spectroscopic, electrochemical, biological recognition, and molecularly imprinted polymers (MIPs)-based sensing strategies. The roles of sample pretreatment techniques, including SPE, MSPE, DLLME, and MIP-assisted enrichment, are evaluated in relation to enrichment capability, matrix tolerance, and compatibility with subsequent detection. Recent developments in MIP nanocomposites based on metal-organic frameworks, covalent organic frameworks, carbon nanomaterials, quantum dots, and magnetic materials are further discussed, highlighting their potential for integrating selective recognition and signal enhancement. LC-MS/MS remains the preferred approach for reliable trace-level confirmation, while fluorescence, electrochemical, and MIP-based sensors offer opportunities for rapid and field-deployable monitoring. A six-dimensional framework is proposed to evaluate analytical performance beyond detection limits. Future efforts should focus on improving water compatibility, antifouling properties, recognition-site uniformity, and validation under realistic environmental conditions.