Grapefruit peel activated carbon for multi-analyte microextraction in water analysis through rotating disk sorptive extraction

In the realm of green analytical chemistry, there is growing interest in sorbent phases derived from natural materials like grapefruit peels as promising alternatives to commercial sorbent phases. Initially, the effectiveness of grapefruit peels in their natural state was compared to activated carbons treated with activating agents as a sorbent phase in rotating disk sorptive extraction (RDSE). The conditions for synthesizing activated carbon were optimized by adjusting the activating agent variables, proportions, and temperatures to obtain an efficient material for extracting ethylparaben (EP), propylparaben (PP), ibuprofen (Ibu), triclosan (TCS), bisphenol A (BPA), and 17-α-ethinylestradiol (EE2) using rotating disk sorption extraction technique from aqueous samples. The optimal conditions were determined to be activation with ZnCl₂ at a 1:1.2 ratio (material: activating reagent) and carbonization at 400 °C (AC400(Z1.2)). Characterization revealed a hydrophilic microporous material with a large surface area and aromatic structure, confirming its potential as a sorbent phase for aqueous sample preparation. The application of AC400(Z1.2) sorbent phase in RDSE in river water confirmed its effectiveness, revealing EP, PP, Ibu, TCS, and BPA in concentrations ranging from 0.18 to 2.8 µg l^-1, with EE2 concentration below the limit of detection. Reusability studies demonstrate that this material can be reused for the simultaneous extraction of analytes in at least two consecutive extractions without requiring additional treatment between extractions. This material proves to be an economical and bio-based alternative to commercial sorbent phases. Finally, its application in RDSE was evaluated using green analytical chemistry metrics (AGREEprep and BAGI), resulting in a methodology with a low environmental impact.