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Related Experiment Video

Updated: Jun 28, 2026

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera

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Published on: December 27, 2018

Primary photoproducts and half-lives.

J Burhenne¹, M Ludwig, P Nikoloudis

¹Department of Ecological Chemistry and Ecotoxicology, University of Kassel, Nordbahnhofstrasse 1a, D-37213, Witzenhausen, Germany.

Environmental Science and Pollution Research International

|January 1, 1997

Summary

Photolytic decomposition of fluoroquinolone antibiotics in water occurs rapidly, with half-lives ranging from minutes to hours. This process alters the piperazine ring and leads to partial mineralization, forming new degradation products.

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Area of Science:

Environmental Chemistry
Photochemistry
Pharmaceutical Science

Background:

Fluoroquinolone antibiotics are widely used, leading to their presence in aquatic environments.
Understanding the environmental fate of these pharmaceuticals is crucial for assessing ecological risks.

Purpose of the Study:

To investigate the photolytic degradation kinetics of four fluoroquinolone carboxylic acids in pure water.
To identify and characterize the photoproducts formed during irradiation.
To estimate the environmental half-life of enrofloxacin.

Main Methods:

Photolytic decomposition experiments using a xenon lamp (200 W/m²).
Analysis of degradation products using High-Performance Liquid Chromatography (HPLC), Mass Spectrometry (MS), Gas Chromatography-Mass Spectrometry (GC/MS), and Proton Nuclear Magnetic Resonance (¹H-NMR).
Calculation of environmental half-life using the GCSOLAR program.

Main Results:

Half-lives in pure water ranged from 20.6 minutes (danofloxacin) to 105.9 minutes (norfloxacin).
Photodegradation primarily involved alterations to the piperazine ring.
Photomineralization of ¹⁴C-labeled enrofloxacin yielded 26.4% ¹⁴CO₂.
Environmental half-life of enrofloxacin varied from 1.8 to 55.4 hours based on season and latitude.

Conclusions:

Fluoroquinolone carboxylic acids undergo relatively rapid photolytic decomposition in aquatic systems.
The degradation pathway involves structural modifications, particularly of the piperazine ring.
Photodegradation contributes to the environmental attenuation of these antibiotics, but transformation products require further study.