Simultaneous determination of four aflatoxins using dispersive micro solid phase extraction with magnetic bimetallic MOFs composite as a sorbent and high-performance liquid chromatography with fluorescence detection

Aflatoxins (AFs) are known as a class of food-contaminating organic compounds, and determining them with appropriate methods is vital for human health. Therefore, a dispersive micro solid phase extraction method was presented as a green sample preparation procedure to extract and preconcentrate aflatoxin B1 (AF-B1), aflatoxin B2 (AF-B2), aflatoxin G1 (AF-G1), and aflatoxin G2 (AF-G2) in spiked real water and rice samples before determining them by high-performance liquid chromatography with fluorescence detection. Firstly, a bimetallic metal–organic framework (Bimetallic-MOF), amine-functionalized Cu/Ni bimetallic-MOF, was synthesized by hydrothermal technique as a sorbent component. Then, the sorbent was magnetized using Fe3O4 nanoparticles by the sol–gel method. The ability of the sorbent to extract AFs was compared with the sorbent component. Affective parameters in the method were evaluated using an experimental design strategy. Under the optimum extraction conditions, the linear ranges of AF-B1, AF-B2, AF-G1, and AF-G2 were 0.15–77.6, 0.04–64.8, 0.15–79.2, and 0.11–69.5 ng mL−1 with R2 higher than 0.9938, respectively. The limits of detection and limits of quantitation of the method to determine AFs were in the ranges of 0.1–0.04 and 0.04–0.15 ng mL−1, respectively. Intra-day and inter-day RSDs for triplicate measurement of AFs at three concentrations of 0.2, 2.0, and 20.0 ng mL−1 were lower than 3.9 and 4.4 %. Pre-concentration factors for determining AFs at a concentration of 5.0 ng mL−1 were between 596 and 637. The recoveries and RSDs for analyzing spiked real water and rice samples were in the range of 92.0–97.8 % and 4.1–7.6 %, respectively, indicating the method has the appropriate ability as a sample preparation and determination method for determining of AFs.