Upcycled Coffee Waste as Sustainable Sorbents for Monitoring Organophosphorus Pesticides in Environmental Waters

This study presents a solid-phase extraction (SPE) method using upcycled coffee waste, specifically acid-treated spent coffee grounds, as sustainable biosorbents for the LC-MS/MS determination of malathion, disulfoton, and chlorpyrifos in environmental waters. Eight coffee-derived materials produced through distinct chemical and thermal pretreatments were fully characterized by FTIR, SEM, TGA, BET, and zeta potential analyses. Acid-treated spent coffee grounds were identified as the most efficient sorbent and subsequently optimized using a 2^5-1 fractional factorial design. The optimized conditions (conditioning pH 3.0, sample pH 3.0, 25 mg of sorbent, 10 mL of sample, and 0.5 mL of eluent) provided wide linear ranges (5.0-250.0 μg L^-1 for malathion; 25.0-250.0 μg L^-1 for disulfoton and chlorpyrifos), low LOQs (5.0 μg L^-1 for malathion; 25.0 μg L^-1 for disulfoton and chlorpyrifos), recoveries between 85.9 and 109.3%, and precision with CV ≤15%. The method achieved an AGREEPREP score of 0.64, indicating strong alignment with Green Analytical Chemistry principles. Application to real surface and groundwater samples demonstrated its suitability for detecting organophosphorus residues, confirming the analytical performance and practical applicability of coffee-waste-based sorbents for environmental monitoring.