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

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 < 12%), lower LODs (0.4-1.0 mu g/kg) and LOQs (1.0-4.0 mu g/kg) than existing methods. In addition, consumption of the adsorbent was reduced, and the MSPE operation is simple and rapid relative to alternatives. These results suggest the proposed method has potential for use in the analysis of lipophilic marine biotoxins in shellfish samples.