Determination of multi-class emerging contaminants in sludge and recovery materials from waste water treatment plants: Development of a modified QuEChERS method coupled to LC-MS/MS

Recycling and recovering valuable resources from wastewater treatment plants is an important aspect in circular economy. The safe use of sludge and sludge-related products deriving from wastewater treatment strictly depends on their chemical contamination, especially by emerging pollutants. In this work, an analytical method was developed for the determination of a range of selected compounds, included in a recent European watch-list (macrolides, fluoroquinolones, neonicotinoids, carbamates and estrogens), in recovery materials from innovative pilot systems. Both the instrumental analysis by high-performance liquid chromatography-tandem mass spectrometry and the pre-treatment strategy (quick, easy, cheap, effective, rugged and safe technique) were optimized for the purpose. The final method performance were evaluated, revealing determination coefficients (R2) of 0.993-0.9999 for the matrix-matched calibration curves, good accuracy (recovery 68-104% and matrix effect 70-123%), satisfactory precision (relative standard deviation <20%) and limits of detection and quantitation in the low ng g(-1) levels. Ten different recovery material samples were analyzed, showing contamination by few analytes, mainly antibiotics and estrone; ciprofloxacin and azithromycin were the most abundant compounds (up to 500-600 ng g(-1)). On the contrary, neonicotinoid pesticides were not detected, except for one sample (sample 10, the only compost material). The application of the described method is an essential part of a broader investigation on the suitability and safety of innovative materials coming from waste water treatment plants, in the view of a risk assessment related to their usage.