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Identification of Pharmaceuticals in The Aquatic Environment Using HPLC-ESI-Q-TOF-MS and Elimination of Erythromycin Through Photo-Induced Degradation
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Nitrate-induced photodegradation of atenolol in aqueous solution: kinetics, toxicity and degradation pathways

Yuefei Ji1, Chao Zeng, Corinne Ferronato

  • 1State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, PR China.

Chemosphere
|April 14, 2012
PubMed

Insights

The photodegradation of atenolol (ATL) in natural waters is enhanced by nitrate ions, with hydroxyl radicals playing a key role. This process effectively reduces ATL toxicity, although complete mineralization is not achieved.

Area of Science:

  • Environmental Chemistry
  • Photochemistry
  • Ecotoxicology

Background:

  • Beta-blockers like atenolol (ATL) are frequently detected in natural waters due to widespread use.
  • Understanding the environmental fate and transformation of pharmaceuticals is crucial for water quality assessment.

Purpose of the Study:

  • To investigate the photolysis behavior of atenolol (ATL) in the presence of nitrate ions.
  • To identify the photodegradation products of ATL and evaluate their toxicity.
  • To elucidate the role of nitrate ions and other water constituents in ATL photodegradation.

Main Methods:

  • Simulated solar irradiation experiments were conducted to study ATL photodegradation kinetics.
  • Hydroxyl radical's role was assessed using isopropanol as a molecular probe.
  • Photodegradation products were identified using solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS).
  • Toxicity of phototransformation products was evaluated using Daphnia magna.

Main Results:

  • ATL photodegradation followed pseudo-first-order kinetics and was significantly enhanced by increasing nitrate concentrations.
  • Hydroxyl radical was identified as the primary reactive species in the photolysis process.
  • Bicarbonate and humic substances influenced ATL photodegradation rates through pH effects and light attenuation/radical scavenging.
  • While ATL transformation reached 72% in 240 min, total organic carbon (TOC) reduction was only 10%, indicating intermediate product formation.
  • Identified photoproducts showed reduced toxicity to Daphnia magna compared to the parent compound.

Conclusions:

  • Nitrate-induced photodegradation is an effective pathway for atenolol removal and toxicity reduction in natural waters.
  • The photodegradation process leads to the formation of intermediate products rather than complete mineralization.
  • Environmental factors such as pH, bicarbonate, and humic substances modulate the efficiency of ATL photodegradation.

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