Extraction aflatoxins from cereals using agerogel @ COF composite and evaluating ultraviolet and microwave...

A dispersive solid-phase extraction method was proposed for the extraction of aflatoxins (B1, B2, G1, and G2) from cereal samples. A covalent-organic framework and graphene aerogel composite were evaluated for their capacity to extract and preconcentrate aflatoxins in the microextraction method. In the proposed method, aflatoxins were extracted with deionized water and acetonitrile (9:1, v/v), aflatoxins were adsorbed to a small amount (10 mg) of the sorbent, desorbed with a low volume of acetonitrile, and determined by high performance liquid chromatography-fluorescence detection. The extraction conditions including the type and amount of adsorbent, stirring conditions, concentration of NaCl, pH, and the type and volume of elution solvent optimized using a "one-variable-at-a-time" strategy. Under these optimized conditions, aflatoxins were effectively extracted from the cereal samples. Good linearity was obtained with correlation coefficients (r²) of 0.999, 0.996, 0.999, and 0.987 for aflatoxins B₁, B₂, G₁, and G₂, respectively. The detection limits for aflatoxins B₁, B₂, G₁, and G₂ were 0.014, 0.009, 0.021, and 0.012 μg/kg, respectively and the quantitation limits were 0.047, 0.032, 0.064, and 0.04 μg/kg respectively. The extraction recoveries of the analytes ranged from 41.7 to 52.6% using the developed method. The relative standard deviations for intra (n = 6) and inter-day (n = 6) precisions for aflatoxins at two concentration levels (2 and 5 μg/kg) were ≤ 8.3% and ≤ 10.2%, respectively. These results indicate that the suggested extraction protocol combined with the detection system can be applied for the sensitive analysis of trace amounts of aflatoxins in food samples.