[Simultaneous determination of four aflatoxins in Citrus reticulatablanco by ultra performance liquid chromatography coupled with immunomagnetic beads for enrichment and purification].

Immunomagnetic beads (IMBs) were formed by coupling the ProtElut NHS (N-hydroxysuccinimide) magnetic beads and anti-aflatoxins monoclonal antibody. The synthesized IMBs presented uniform size, good magnetic property and specific selectivity. In this work, a novel and facile pretreatment method of sample enrichment and purification based on the IMBs for the determination of aflatoxins (AFs) (AFB1, AFB2, AFG1, AFG2) in Citrus reticulatablanco samples by ultra performance liquid chromatography (UPLC) were developed. The sample was extracted with 20% (v/v) methanol-PBS buffer solution (pH 7.4), followed by a cleanup procedure with the IMBs. The target compounds were eluted using 1 mL methanol. The four afatoxins were separated on an ACQUITY UPLC HSS T3 C18 column (100 mm x 2.1 mm, 1.8 μm) adopting a gradient program within 12 min. The UPLC equipped with a fluorescence detector with a special mercury/xenon lamp was used to detect the aflatoxins. The satisfactory correlation coefficients (r2 > 0.999) of the four aflatoxins were obtained within their respective linear ranges. The limits of detection (S/N = 3) were between 0.013 μg/kg and 0.038 μg/kg, and the limits of quantification (S/N = 10) were between 0.044 μg/kg and 1.2 μg/kg. The recoveries were in the range of 63.9% - 115.0% with the relative standard deviations (RSDs) of 0.4% - 14.2%. The validation results meet the requirements of trace assay. It's indicated that the IMBs were good pretreatment alternatives and the developed method is simple, fast, accurate, and can be applied for the simultaneous determination of the four aflatoxins in Citrus reticulatablanco.