Miniaturized and modified QuEChERS method with mesostructured silica as clean-up sorbent for pyrrolizidine alkaloids determination in aromatic herbs

Abstract

This work proposes the miniaturization and modification of the QuEChERS strategy using different large pore mesostructured silicas, non-modified and modified with amino groups (NH₂), as dispersive clean-up sorbents for multi-component extraction of 21 pyrrolizidine alkaloids from different aromatic herbs, combined with ultra-high performance liquid chromatography coupled to tandem mass spectrometry analysis. The procedure was miniaturized by reducing the amounts of sample (0.2 g), solvents (2 mL), clean-up sorbents (25 mg sorbent + 150 mg MgSO₄) and partitioning salts (0.65 g) employed. Best results were achieved using mesostructured silicas (LP-MS-NH₂) than conventional PSA. The method was validated (overall recoveries 73-105%) and applied to the analysis of 17 samples. All the samples were contaminated with PAs (average concentration 262 µg/Kg). Thyme and basil samples were the most contaminated, whereas rosemary was the least. Lasiocarpine, senecivernine N-oxide and europine N-oxide were the main PAs that contributed to their contamination.

Keywords: Aromatic herbs; Food safety; Mesostructured silicas; Pyrrolizidine alkaloids; UHPLC-MS/MS; µ-QuEChERS.