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).