One-pot pH adjustment, derivatization, and extraction using a multi-functional magnetic adsorbent for analysis of furfural compounds in foods

Furfural compounds are important markers of thermal processing in foods and herbal products. However, their analysis in complex samples presents substantial challenges due to matrix interferences and limited detectability. This study introduces a multi-functional magnetic adsorbent synthesized via one-pot grinding, integrating pH adjustment, derivatization, and extraction into a single step. The adsorbent releases citric acid and 2,4-dinitrophenylhydrazine upon dispersion, leading to a pH decrease (∼2.5) and a light-yellow color change, which confirms the initiation of pH adjustment and derivatization. Meanwhile, magnetite nanoparticles (Fe 3 O 4 ) and hydroxylated multi-walled carbon nanotubes self-assemble to extract analytes. Combined with liquid chromatography–ultraviolet analysis, the method achieved satisfactory linearity (0.05–5 μg/mL, R 2  > 0.992), low limits of detection (8.0–13.7 ng/mL), and high recoveries (87.7–99.4%) with relative standard deviations ≤12.1%. It was successfully applied to diverse samples, including teas, juices, coffees, and herbal liquids. Optimization confirmed a 50% ethanol content, a 3 mL sample volume, and 30 min incubation at 30 °C. This strategy integrates derivatization, pH adjustment, and extraction into a self-activated platform suitable for automated operation. It simplifies workflows, improves reproducibility, and shows strong potential for high-throughput food safety and quality monitoring.