Reversed-phase/weak anion exchange magnetic mesoporous microspheres for removal of matrix effects in lipophilic marine biotoxins analysis by ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry

Abstract Magnetic solid-phase extraction (MSPE), using a new reversed-phase/weak anion exchange mix-mode mesoporous magnetic SiO2 adsorbent, was assessed as an approach for reducing matrix effects in the analysis of six lipophilic marine biotoxins in shellfish using ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The adsorbent showed greater adsorption capacity and selectivity for the analytes and, thus, the MSPE microspheres reduced the matrix effects significantly in the subsequent analysis. In the UPLC-MS/MS analysis, precursor and product ions of the analytes were monitored quantitatively and qualitatively using multiple reaction monitoring and product ion confirmation modes. The proposed method exhibited a linear correlation of 0.9980–0.9991 in the working range for azaspiracids (2.0–200.0 ng/mL) and okadaic acid and its derivatives dinophysistoxins (4.0–200.0 ng/mL) with satisfactory recoveries (82.8–118.6%, RSD