Identification and characterization of tebuconazole transformation products in soil by combining suspect screening and molecular typology

Pesticides generate transformation products (TPs) when they are released into the environment. These\r\nTPs may be of ecotoxicological importance. Past studies have demonstrated how difficult it is to predict\r\nthe occurrence of pesticide TPs and their environmental risk. The monitoring approaches mostly used in\r\ncurrent regulatory frameworks target only known ecotoxicologically relevant TPs. Here, we present a\r\nnovel combined approach which identifies and categorizes known and unknown pesticide TPs in soil by\r\ncombining suspect screening time-of-flight mass spectrometry with in silico molecular typology. We\r\nused an empirical and theoretical pesticide TP library for compound identification by both non-target\r\nand target time-of-flight (tandem) mass spectrometry, followed by structural proposition through a\r\nmolecular structure correlation program. In silico molecular typology was then used to group TPs according\r\nto common molecular descriptors and to indirectly elucidate their environmental parameters by\r\nanalogy to known pesticide compounds with similar molecular descriptors. This approach was evaluated\r\nvia the identification of TPs of the triazole fungicide tebuconazole occurring in soil during a field\r\ndissipation study. Overall, 22 empirical and 12 yet unknown TPs were detected, and categorized into\r\nthree groups with defined environmental properties. This approach combining suspect screening timeof-flight\r\nmass spectrometry with molecular typology could be extended to other organic pollutants and\r\nused to rationalize the choice of TPs to be investigated towards a more comprehensive environmental\r\nrisk assessment scheme.