▎ 摘　　要

In this study, the new approach of dispersive micro-solid phase extraction using a magnetic sheet was developed. A circle magnetic sheet (diameter, 25 mm; thickness, 0.4 mm) was perforated and used as a support for fixing and re-collecting three-dimensional magnetic graphene nanoparticles as an adsorbent. The method was coupled with high-performance liquid chromatography-fluorescence detector (HPLC-FLD) and utilized for extraction of aflatoxins (B-1, B-2, G(1), and G(2)). All steps of the extraction procedure including sample loading, sorbent dispersion, and re-collecting, and elution were performed using a syringe. The significant parameters such as adsorbent amount, desorption conditions, flow rates, ionic strength, and pH which influence extraction efficiency was investigated. The linear dynamic range was 0.2-1000 mu g kg(-1), with a coefficient of determinations > 0.9914. The limits of detection and quantification were 0.06-0.1 and 0.20-0.33 mu g kg(-1), respectively. The developed method was applied to the analysis of aflatoxins in real white and moldy bread samples, and the related extraction recoveries of the four aflatoxins were obtained in the range of 59-69% (RSD, 4.4-5.6%).