Analytical methodology for challenging persistent, mobile, and toxic substances in vegetal matrices after irrigation with contaminated water

Reusing wastewater for irrigation is proposed as a strategy to address water scarcity. However, the long-term environmental consequences of this practice are still unknown, especially when reclaimed water contains contaminants of emerging concern, such as persistent, mobile, and toxic (PMT) compounds, due to the inefficiency of wastewater treatment plants in removing certain pollutants. As a result, irrigation with contaminated water could lead to their uptake by crops and enter the food chain. While data on the presence of PMTs in environmental samples is starting to emerge, the analysis of certain compounds in vegetable matrices remains unexplored. In this study, an analytical methodology was developed and validated for the determination of 8 PMTs (i.e., benzophenone-3, clarithromycin, imazalil, metformin, sulpiride, terbutryn, tiapride, and tramadol) in escarole, tomatoes, and tomato leaves. The proposed analytical methodology used a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction method prior to mixed-mode liquid chromatography tandem mass spectrometry analysis. Method validation, performed according to SANTE guidelines, presented satisfactory results at studied concentrations (1, 10 and 100 ng·g^-1 for each compound/matrix combination, except for metformin in escarole (50 and 500 ng·g^-1). Recoveries ranged from 70 to 120 %, with a precision of ≤ 20 % for most compounds. Benzophenone-3 and tiapride, for which no isotopically labelled internal standard was available, could be adjusted by applying a correction factor. The limit of quantification was 1 ng·g^-1 for all compounds in the three matrices, except for benzophenone-3 and metformin in both escarole and tomato leaves. The applicability of the method was tested by analysing samples from an experimental greenhouse plot where crops were irrigated with water spiked with the selected PMTs.