ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Autofluorescence-based monitoring of ofloxacin and norfloxacin in tap and river waters from Senegal

Abdourahmane Khonté, Diène Diégane Thiaré, Jean Pierre Bakhoum, Diégane Sarr, Ndeye Arame Diop, Pape Abdoulaye Diaw, Atanasse Coly, and Philippe Giamarchi

Laboratoire Matériaux, Electrochimie et Photochimie Analytique, Université A. Diop de Bambey (UADB), Bambey, Sénégal

E-mail: philippe.giamarchi@univ-brest.fr

Received: 1 December 2025  Accepted: 9 May 2026

Abstract:

This study aims to assess the feasibility of conducting online screening for antibiotic residues in natural waters. Two analytical methods are studied and compared: the classical fluorescence determination after sampling and transportation to the laboratory (FLUO), and an automatic on-site monitoring fluorescence system (AUTOFLUO), applied for the first time to antibiotics. We focus on two widely used molecules in Senegal, ofloxacin (OFX) and norfloxacin (NFX), and assess their toxicity to aquatic flora and fauna. We conduct physicochemical studies on the two antibiotics to determine characteristic excitation and emission wavelengths and fluorescence lifetimes, and then assess the influence of pH and solvent. Then, calibration curves were established under optimal analytical conditions: maximum excitation wavelengths of 275 nm for OFX and 287 nm for NFX; maximum emission bands of 502 nm and 435 nm, respectively; and an optimal pH of 4. The FLUO method yielded an LOD value of 1.55 ng mL⁻¹ for OFX and a value of 0.58 ng mL⁻¹ for NFX. The AUTOFLUO method yielded lower LOD values, specifically 0.07 ng mL⁻¹ for OFX and 0.03 ng mL⁻¹ for NFX. The more sensitive AUTOFLUO method was employed using the standard addition procedure to analyse both antibiotics in tap water and river waters from Senegal. The results demonstrate that the AUTOFLUO method is accurate, sensitive, reproducible, and repeatable, making it an effective solution for monitoring antibiotics in natural waters.

Graphical abstract

Keywords: Fluoroquinolones; Ofloxacin; Norfloxacin; Fluorescence; Autofluorescence; Surface water; Senegal; Surface water and tap water analysis

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-05036-5

Chemical Papers 80 (9) 10677–10689 (2026)