Integrated in-syringe magnetic sheet solid-phase extraction and dispersive liquid-liquid microextraction for determination of aflatoxins in fresh and moldy breads.

BACKGROUND: Magnetic three-dimensional graphene-based nanoadsorbents have unique characteristics such as large surface area, good thermal and chemical stability, and high adsorption capacity that make them efficient materials in sorbent-based extraction techniques. In this study, four aflatoxins (AFs) were analyzed in bread samples using magnetic three-dimensional graphene as the adsorbent phase in dispersive micro solid-phase extraction.

RESULTS AND CONCLUSIONS: In-syringe magnetic sheet solid-phase extraction based on magnetic three-dimensional graphene in tandem with dispersive liquid-liquid microextraction was used for the extraction and preconcentration of the target AFs. The effect of significant parameters of the method was investigated and the optimum conditions were determined as follows: adsorbent dosage, 20 mg; desorption/disperser solvent (methanol) volume, 700 μL; desorption solvent flow rate, 0.7 mL min-1 ; pH, neutral; salt (NaCl) concentration, 10% (w/v); extraction solvent (chloroform) volume, 250 μL; and centrifugation rate (and time), 4000 rpm (5 min). The limits of detection and quantification were in the ranges 0.043-0.083 and 0.14-0.28 μg kg-1 , respectively. The extraction method was followed by the HPLC technique with fluorescence detection and applied to the determination of the AFs in four different Iranian fresh and moldy bread samples. The relative recoveries were in the range 84-107% with relative standard deviations of 3.9-8.6%. © 2019 Society of Chemical Industry.