Biochar from sewage sludge as a sustainable and green dispersive solid phase adsorbent in the clean-up of QuEChERS extracts: First application to the LC–MS/MS analysis of contaminants of emerging concern in edible crop samples

Biochar from pyrolysis of sewage sludge (SS-BC) was tested for the first time as dispersive solid-phase extraction (d-SPE) sorbent in the clean-up of QuEChERS extracts of rocket, tomato, and strawberry for the analysis of a wide group of contaminants of emerging concern, which included 23 analytes belonging to the classes of pharmaceutical compounds (PhCs), perfluorinated alkyl substances (PFASs), and sunscreen agents (SAs). The SS-BC was compared for its clean-up efficiency with graphitized carbon black (GCB) and styrene-divinylbenzene copolymer (SDVB), evaluating recovery efficiency (R) in matrix-free experiments, matrix effect (ME) reduction and apparent recovery (AR%). SS-BC at 10 mg/mL of extract showed high ME removals for all target analytes, but variable recoveries (R% = 67 ± 36), inversely and strongly correlated with the number of aromatic rings and directly correlated with the size and hydrophobicity of the molecule. BC was effective as d-SPE sorbent for the QuEChERS analysis of PFAS (AR% = 96 %–136 %, depending on the crop analysed), while for the simultaneous analysis of both non-aromatic and aromatic analytes better results were obtained by properly mixing SS-BC with SDVB. The proposed QuEChERS extraction and clean-up approach was compared for its environmental greenness with previously published methods, showing the highest score (0.53 vs. 0.35–0.47). Based on the results obtained, SSBC represents a sustainable and cost-effective bio-based material that can replace GCB as d-SPE sorbent for the analysis of a wide variety of emerging contaminants, covering a broad range of physicochemical properties (e.g., Log D at pH = 7 in the range − 2–6.8) in various pigmented crop extracts.