Split-flow electroextraction with in-situ matrix cleanup for analysis of shellfish toxins.

The analysis of lipophilic shellfish toxins (LSTs) in foods is severely hampered by matrix interference and laborious sample preparation. To address these issues, we developed a split-flow in-situ matrix cleanup electroextraction (SF/ISMC-EE) method coupled with LC-MS/MS. This approach tackles two major limitations in electric field-assisted sample preparation (EFASP): bubble formation and difficulty of direct extraction from complex solid matrices. SF/ISMC-EE uses a multi-channel split-flow design to suppress bubbles, enabling high-voltage rapid enrichment (300 s). Chitosan-mediated in-situ cleanup releases analytes and blocks impurity co-extraction, eliminating need for matrix-matched calibration. The "electric field + cleanup materials" strategy allows direct electroextraction from solid/semi-solid foods, integrating extraction, cleanup, and enrichment. As the first EFASP method applied to LST analysis, it was validated with certified reference materials and real samples, demonstrating high accuracy, precision, and low detection limits meeting EU regulations. This work provides a robust and efficient tool for food safety monitoring.