Identification of the organic compounds in surface water: Suspect screening using liquid chromatography high-resolution mass spectrometry and in silico toxicity evaluation

Abstract

The suspect screening approach was used to investigate the presence of organic compounds in Lake Guaíba – Brazil based on Liquid Chromatography coupled to Quadrupole-Time of Flight mass spectrometry (LC-QTOF-MS). The library suspect screening consisted of 1450 compounds, which was selected based on the presence of commercially available pesticides (which are not part of the ordinances), pharmaceuticals, drugs of abuse, and their main metabolites. Out of these 1450 compounds, 16 were identified with a suspect screening method in sixty-nine samples carried out for two years in the Lake. The most frequently detected compounds were venlafaxine and its metabolites; desmethylvenlafaxine, benzoylecgonine and its metabolites; cocaine; CGA 321113 (trifloxystrobin metabolite); 4-amino-antipyrine; and quinclorac. Principal Component Analysis (PCA) was used as an exploratory multivariate investigation of data on the detected compounds, and samples were tagged according to site, month, and year of collection to identify temporal and spatial patterns. Results obtained from in silico QSAR models evince the need of performing risk assessment of suspect compounds, for many compounds were found to be mutagenic, toxicant, carcinogenic, and non-readily biodegradable.