Determination of Boscalid and Pyraclostrobin Fungicides from Strawberries in Accordance with Green Analytical Chemistry Strategies

A green variant of the mini-QuEChERS procedure was developed for the extraction of boscalid and pyraclostrobin from strawberries, these pesticides being commonly used for spraying strawberry plants. To enhance the greenness and overall environmental sustainability of the extraction method, the selection of green extraction solvent, testing of custom-made clean-up sorbents and miniaturization of the extraction procedure were studied. N-amyl acetate as a green reagent was selected as the extraction solvent. Carbonaceous sorbents made from furniture manufacture waste were prepared by pyrolyzation and proposed as a green alternative to traditionally used graphitized carbon black in the dispersive solid phase extraction clean-up step of the mini-QuEChERS procedure. The green mini-QuEChERS procedure was combined with GC-MS analysis and the method was validated. The limit of detection and quantification were 0.58 μg/kg and 1.75 μg/kg for boscalid and 4.60 μg/kg and 13.8 μg/kg for pyraclostrobin, respectively. The extraction recoveries ranged from 75% to 92%. Repeatability, expressed as the relative standard deviation was 13% and 6% for boscalid and pyraclostrobin at 25 μg/kg, 6% and 4% for boscalid and pyraclostrobin at 125 μg/kg, and 9% and 11% for boscalid and pyraclostrobin at 250 μg/kg. Within-laboratory reproducibility ranged from 4% to 12% at the three concentration levels. The analytical greenness of the method was evaluated by AGREE (0.56), Analytical EcoScale Assessment (87 points, excellent green analysis) and Complex MoGAPI (80 points). The developed and validated method was used for determination of boscalid and pyraclostrobin residues in local strawberries samples.