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Aqueous chlorination of sulfamethazine and sulfamethoxypyridazine: Kinetics and transformation products identification
Author(s) -
Nassar Rania,
Rifai Ahmad,
Trivella Aurélien,
Mazellier Patrick,
Mokh Samia,
AlIskandarani Mohamad
Publication year - 2018
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.4191
Subject(s) - chemistry , chlorine , ultrapure water , aqueous solution , reactivity (psychology) , sulfonamide , reaction rate constant , chromatography , environmental chemistry , tandem mass spectrometry , mass spectrometry , kinetics , organic chemistry , chemical engineering , medicine , physics , alternative medicine , pathology , quantum mechanics , engineering
Sulfonamides (SNs) are synthetic antimicrobial agents. These substances are continually introduced into the environment, and they may spread and maintain bacterial resistance in the different compartments. The chlorination of 2 SNs, namely, sulfamethazine (SMT) and sulfamethoxypyridazine (SMP), was investigated to study their reactivity with chlorine at typical concentrations for water treatment conditions. Experiments conducted in purified water show an acceleration of SMT and SMP degradation of a factor 1.5 by comparison to drinking water matrix. This difference is due to pH variation and competitive reactions between SNs and mineral and organic compounds, with chlorine in drinking water. In the presence of an excess of chlorine (6.7 μmol·L −1 ) in ultrapure water at pH 7.2, second‐order degradation rate constants were equal to 4.5 × 10 2 M −1 ·s −1 and 5.2 × 10 2 M −1 ·s −1 for SMT and SMP, respectively. The structures of transformation products were investigated by liquid chromatography tandem mass spectrometry analyses with equimolar concentrations between chlorine and SNs. SO 2 elimination, cyclization, and electrophilic substitutions were the main pathways of by‐products formation. Moreover, the toxicity of the proposed structures was predicted by using toxicity estimation software tool program. The results indicated that most by‐products may present developmental toxicity.