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Photocatalytic degradation of phenyl‐urea herbicides chlortoluron and chloroxuron: characterization of the by‐products by liquid chromatography coupled to electrospray ionization tandem mass spectrometry
Author(s) -
Amorisco A.,
Losito I.,
Carbonara T.,
Palmisano F.,
Zambonin P.G.
Publication year - 2006
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2472
Subject(s) - chemistry , electrospray ionization , electrospray , tandem mass spectrometry , mass spectrometry , chromatography , high performance liquid chromatography
The first stages of the photocatalytic degradation of the compounds chlortoluron [3‐(3‐chloro‐4‐methylphenyl)‐1,1‐dimethylurea] and chloroxuron [3‐[4‐(4‐chlorophenoxy)phenyl]‐1,1‐dimethylurea], belonging to the class of phenyl‐urea herbicides, were investigated using high‐performance liquid chromatography (HPLC) coupled to electrospray ionization ion trap tandem mass spectrometry (ESI‐IT‐MS/MS). Degradation was accomplished under solar radiation, using TiO 2 embedded into a polyvinylidene fluoride (PVDF) transparent matrix as a heterogeneous photocatalyst. Aliquots of the chlorinated herbicide solutions were withdrawn at different times and subjected to gradient elution, reversed‐phase HPLC separations, specifically optimized to obtain the highest resolution between peaks related to the herbicide degradation by‐products. The latter were then investigated using MS detection; in particular, MS/MS measurements were made and structural information was obtained from the interpretation of fragmentation data. Several by‐products were identified; the most important ones are hydroxylated compounds arising from the interaction between the two chlorinated herbicides and OH radicals generated at the TiO 2 surface under irradiation. Other by‐products were generated by slightly different processes, namely demethylation, dearylation and dechlorination, eventually followed by interaction with OH radicals. Copyright © 2006 John Wiley & Sons, Ltd.