Extraction of aflatoxins by using mesoporous silica (type UVM-7), and their quantitation by HPLC-MS

A solid-phase extraction procedure has been developed by using a sorbent derived from UVM-7 mesoporous silica. The sorbent was applied to the extraction of aflatoxins B₁, B₂, G₁ and G₂ from tea samples followed by HPLC with mass spectrometric detection. The sorbent was characterized by transmission electron microscopy, nuclear magnetic resonance, X-ray diffraction and nitrogen adsorption-desorption. UVM-7 is found to be the best solid phase. The amount of solid-phase, type and volume of eluent, pH value and ionic strength and breakthrough volume were optimized. Following the recommended procedure, recoveries between 96.0 and 98.2% were achieved, with RSD values of <5.1%, and the limits of detection are in the range from 0.14 to 0.7 μg·kg^-1. The material is reusable. The method was applied to the analysis of real tea samples. A low matrix effect is found, and recoveries are >88%. The results were compared with those obtained by immunoaffinity columns as a reference method. Only low concentrations of aflatoxin G₂ were found in some samples, and results obtained with both methods are shown to be statistically sound and comparable. Graphical abstractSchematic representation of a mesoporous silica sorbent (type UVM-7) for the extraction of aflatoxins (AF) from tea by solid-phase extraction (SPE), and its determination by liquid chromatography. The morphology of the material allows to retain the analytes very well.