Analysis of fluoroquinolone antibiotics in sediments: Optimization of extraction and cleanup of sediment samples for analysis of fluoroquinolones

Abstract

Fluoroquinolone antibiotics (FQs) are emerging environmental contaminants of significant concern due to their extensive use, persistence, and potential to promote antimicrobial resistance. Their strong adsorption to solid matrices, particularly sediments, makes these compartments long-term reservoirs, necessitating robust and efficient analytical methods for accurate monitoring. This work aimed to develop and optimize a complete analytical workflow for the extraction, cleanup, and quantification of multiple FQs in complex sediment samples. T o achieve the necessary sensitivity and selectivity for trace-level environmental analysis, the core chromatographic method initially developed was transferred to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform. Concurrently, a multi-cycle Ultrasonic-Assisted Extraction (UAE) protocol was developed, incorporating a buffered solvent system and a tandem solid-phase extraction (SPE) cleanup, to overcome the strong analyte-matrix interactions and significantly improve recovery efficiency. The final optimized method was rigorously validated and subsequently applied to the analysis of surface sediment samples collected from the Ave River in Portugal. The results demonstrate that the finalized UAE-SPE-LC-MS/MS method provides a robust, sensitive, and reliable workflow for quantifying trace levels of FQs in environmental sediments. The successful application to real samples confirmed the presence of target antibiotics in the collected sediments, validating the method's effectiveness for environmental monitoring. This work establishes a standardized and optimized protocol for the determination of FQs residues in sediment matrices, providing a valuable tool for improved environmental risk assessment.