Magnetic solid-phase extraction of Sudan dyes from beverages-coated magnetite/silica materials

In this study, a polydopamine-coated magnetite/silica composite material (Fe₃O₄@SiO₂/PDA) was successfully synthesized and characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). By integrating EM-MSPE with high-performance liquid chromatography (HPLC), a novel EM-MSPE-HPLC method was established for the sensitive and accurate determination of Sudan I-IV dyes. Key experimental parameters, such as adsorbent dosage, pH, inorganic salt concentration, adsorption time, voltage, eluent type, eluent volume, and desorption time, were systematically investigated and optimized. Under optimal conditions, the method demonstrated excellent linearity (R² > 0.999) within a concentration range of 5–1000 μg L⁻¹, with limits of detection (LODs) ranging from 0.11 to 0.17 μg L⁻¹. The recoveries of Sudan dyes in real samples ranged from 89.1 % to 101.9 %, with relative standard deviations (RSDs) between 0.3 % and 3.6 %. Furthermore, the Fe₃O₄@SiO₂/PDA adsorbent exhibited consistent performance over ten consecutive extraction cycles without significant loss in recovery efficiency. These findings demonstrate that the proposed method is accurate, reliable, and reproducible for the simultaneous determination of Sudan dyes in complex beverage matrices, offering a robust analytical approach for food safety applications.