Identification of by-products formed during the oxidative transformation of phenylurea pesticides

The goal of this study was to identify the by-products that form during the oxidative degradation of five phenylurea pesticides. Four advanced oxidation processes were used including photolysis, ozonation, heterogeneous photocatalysis, and the combination of photolysis with ozonation. After concentrating the by-products using solid phase extraction, our samples were analyzed by mass spectrometry. We have managed to identify the main products for each pesticide and process, from which we could determine that the main reactions during the application of AOPs were the dehalogenisation and hydroxylation of the aromatic ring, as well as the terminal demethylation and the oxidation of the methyl groups