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.