Simulation of the environmental degradation of diuron (herbicide) using electrochemistry coupled to high resolution mass spectrometry

The environmental degradation of contaminants such as pesticides can hinder the ability of analytical instruments, even high-performance system such as mass spectrometry, to detect and quantify contamination reliably. There is thus a need for developing synthetic approaches that allow the fast identification of contaminants markers that can be later support quantitative analysis. Combining electrochemical cell (EC), liquid chromatography (LC) and electrospray mass spectrometry (MS) (online EC-MS and offline EC-LC-MS) allows the rapid identification of some oxidation products of diuron (DIU) in the absence and in the presence of glutathione. The structural elucidation of DIU oxidation products was based on retention time, m/z ratio in positive mode and fragmentation pattern. Reactions such as hydrolytic dechlorination, hydroxylation, dehydrochlorination, dehydrogenation/hydrogenation, conjugation and dimerization have been successfully mimicked serving applications such as drug metabolism and environmental degradation simulation. The resort to electrochemistry to simulate naturally occurring reaction has been of particular interest for the production of reactive intermediate species. In this study, quinone imines, highly electrophilic chemical intermediates, have been identified as transformation products during the oxidative metabolism of diuron for the first time. The obtained results, supported by theoretical calculations, are useful for predicting and understanding the oxidative DIU degradation pathway. [Display omitted] •Electrochemical behavior of diuron was studied.•Electrochemistry coupled to mass spectrometry (EC-MS) was used as a fast identification of degradation products of diuron.•EC-MS constitutes a fast analytical procedure for the elucidation of reaction pathways.