Magnetic solid-phase extraction of Sudan dyes from beverage using polydopamine-coated magnetite/silica materials

Abstract In this work, a kind of polydopamine-coated magnetite/silica material (Fe3O4@SiO2/PDA) as adsorbents was successfully synthesized and characterized by FT-IR, XRD, and XPS. Based on the above-mentioned adsorbents, a rapid, simple, and efficacious electromagnet-magnetic solid phase extraction (EM-MSPE) was reported and applied to the extraction and determination of Sudan dyes (Sudan I, Sudan II, Sudan III, and Sudan IV included) in the beverage samples. Meanwhile, four Sudanese dyes were separated and determined by high-performance liquid chromatography (HPLC). Significant parameters including adsorbent dosage, pH, inorganic salt concentration, adsorption time, voltage, type, eluent volume and desorption time were investigated and optimized. A good linearity (R2>0.999) with linear range of 5-1000 μg L-1 and the limit of detection (LOD) in the range of 0.11-0.17 μg L-1 were obtained under the optimum experimental conditions. The recoveries of Sudan dyes ranged from 89.1%-101.9%, with the relative standard deviation (RSD) ranging from 0.3% to 3.6% in the analysis of real samples and there was no significant decrease in the extraction recoveries of Sudan dyes after ten uses of Fe3O4@SiO2/PDA. These results illustrated that the present method is effective and accurate with excellent reproducibility for the Sudan dyes in the beverage samples.