Application of new N- and S-doped amorphous carbon in D-μSPE and its combination with deep eutectic solvent-based DLLME for the extraction of some mycotoxins from soymilk

Abstract

A new amorphous carbon-based dispersive micro solid-phase extraction method was developed for the extraction and preconcentration of several mycotoxins from soymilk samples. The extracted analytes were concentrated by a deep eutectic solvent-based dispersive liquid–liquid microextraction method, and then, quantified by a high-performance liquid chromatography-fluorescence detector. The sorbent was prepared from β-cyclodextrin and methionine under mild conditions. The sorbent was doped by N and S, which improved its physicochemical properties. The optimization and validation of the method were performed using the “one-variable-at-a-time” method and International Council Harmonization guideline, respectively. Under the optimal conditions, low limits of detection and quantifications in the ranges of 0.08–0.56 and 0.27–1.9 ng L⁻¹ were obtained, respectively. Also, intra- (n = 6) and inter-day (n = 6) precisions showed an acceptable repeatability of the present work as they were in the ranges of 3.9–6.2 and 4.6–8.9% at a concentration of 3 ng L⁻¹ of each analyte, respectively. Finally, the proposed method was performed on different soymilk samples marketed in Tabriz city, and aflatoxin B₁ was found in all samples. One soymilk was contaminated by ochratoxin A.