A novel green μSPE platform based on magnetic Fe₃O₄-activated carbon and deep eutectic solvents for ultrasensitive determination of rhodamine B in aqueous and food matrices.

Abstract

A novel and green magnetic solid-phase microextraction (μSPE) method was developed using a Fe₃O₄-activated carbon (Fe₃O₄-AC) composite combined with hydrophilic deep eutectic solvents (DES) for the efficient extraction of Rhodamine B (RhB) from aqueous and food matrices. The Fe₃O₄-AC served as both sorbent and dispersant, enabling rapid magnetic recovery. The composite was synthesized and characterized using FTIR, XRD, XPS, SEM, SEM mapping, TEM, and EDX, confirming the successful incorporation of magnetic nanoparticles and the structural integrity. Additionally, the deep eutectic solvent (DES) was characterized through FTIR and 1H NMR spectroscopy. Key extraction parameters were optimized to enhance performance. Spectrophotometric quantification revealed excellent linearity (9.7-990.0 μg/L, R2 = 0.9992), low LOD (3.2 μg/L), and RSDs below 3 %. Recovery rates ranged from 98.66 % to 103.33 % in spiked water samples and 97 % to 99 % in food matrices. This μSPE-DES platform offers high sensitivity, operational simplicity, and cost-effectiveness, aligning well with green chemistry principles and demonstrating strong potential for trace-level analysis of synthetic dyes in complex matrices.