Environmental persistence of fluoroquinolones: Reverse-phase high-performance liquid chromatography-based...

Fluoroquinolone (FQ) antibiotics persist in the environment, posing risks to ecosystems and public health through antimicrobial resistance and bioaccumulation. Effective analytical methods are essential for monitoring these residues and enforcing regulations to limit antibiotic pollution.

This study developed validated reversed-phase high-performance liquid chromatography (RP-HPLC) approaches for the simultaneous detection of five FQs: norfloxacin (NFX), levofloxacin (LFX), enrofloxacin (ENR), ofloxacin (OFX), and ciprofloxacin (CFX). Two chromatographic methods were required due to structural similarities between LFX and OFX. Method I, using an Eclipse Plus phenyl hexyl column, produced retention times of 5.2 min for NFX, 5.7 min for LFX, and 7.9 min for ENR. Method II, utilizing a YMC C18 column, yielded retention times of 8.9 min for OFX and 10.7 min for CFX. Both methods demonstrated high selectivity, specificity, linearity (R ² > 0.998), and precision (relative standard deviation (RSD) < 2 %), with Photodiode Array (PDA) detection at 280 nm. Validation followed International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2R2 guidelines. Environmental samples from West Bengal, including water, soil, chicken muscle, and fish skin, were processed using solid-phase extraction. Residues of all five FQs were detected, ranging from 0.1 to 1.4 μg g^-1. Ofloxacin and CFX were more frequently found in animal-derived samples, whereas NFX and ENR were predominant in water and soil.

The validated RP-HPLC methods provide robust tools for monitoring FQ residues in diverse matrices. The widespread contamination observed highlights the urgent need for stronger surveillance, stricter regulatory enforcement, and comprehensive risk assessment to mitigate antimicrobial resistance and protect public health. © 2026 Society of Chemical Industry.