In silico ecotoxicity assessment of photoinduced imidacloprid degradation using HPLC–HRMS, QSAR and ecotoxicity equivalents

Abstract Background Imidacloprid is among the most widely used insecticides and today found in surface ground water worldwide. It has been registered EU watchlist for monitoring. To prevent imidacloprid from entering bodies, advanced oxidation processes (AOP) have intensely researched. Photo-irradiation proved one of efficient methods to degrade eliminate anthropogenic micropollutants waters. The ecotoxicity assessment photoinduced degradation transformation products especially absence reference standards still heavily explored. Results In this study, UVA UVC irradiation combination with titanium dioxide P25 as photocatalyst were investigated their degrading eliminating effects effectiveness on imidacloprid. Humic acid was natural organic matter additive. High-performance liquid chromatography coupled high-resolution mass spectrometry allowed identify monitor its intermediates yielding seven new structures concentration–time ( c–t ) profiles. correlation application radical scavengers helped distinguish between direct indirect hydroxyl radical-induced mechanisms. identification hydroxylated indicated pathway, which could be suppressed by addition a scavenger. fragments pointed towards absorption-induced degradation. Two degradations traced back mechanism, whereas all other followed mechanism. identified compounds assessed quantitative structure–activity relationship (QSAR) analysis. Most predicted less ecotoxic. Ecotoxicity equivalents (ETEs) introduced allowing classified ranking an overall hazardous potential irradiated solution at given moment. Generally, number substituents inversely correlated ecotoxicity. From c-t curves, time-dependent ETE profiles established. Conclusions Structure elucidation chromatography–high-resolution specific achieved through QSAR hazard ranked based ETEs. profile suitable reflect effect duration allow estimate time required ecotoxicity, may relevant applications wastewater treatment plants.