Development of Sensitive and Selective Methods for Identifcation of Marine Toxins by Liquid Chromatography Tandem Mass Spectrometry

Importance of the Topic

Marine toxins such as diarrhetic shellfish poisoning (DSP) compounds, ciguatoxins (CFP) and tetrodotoxin (TTX) pose significant public health risks when accumulating in seafood. Sensitive and selective instrumental methods are essential to replace animal bioassays, ensure accurate quantitation at low concentration levels, and support regulatory monitoring worldwide.

Study Objectives and Overview

This work aimed to establish robust LC-MS/MS conditions for simultaneous identification of five representative marine toxins: okadaic acid (OA), dinophysistoxins DTX1 and DTX2, ciguatoxin CTX3C, and tetrodotoxin (TTX). The goal was to optimize chromatographic separation, mass spectrometric detection and sample cleanup to achieve ppb-level sensitivity and clear selectivity.

Methodology and Instrumentation

• Instrumentation: Shimadzu UHPLC Nexera X2 coupled to LCMS-8050 triple quadrupole with heated electrospray ionization and MRM detection.
• Chromatographic Columns: Multi-mode ODS (Scherzo SM-C18), reversed-phase ODS (L-column2 ODS) and HILIC (InertSustain Amide PEEK) for TTX.
• Mobile Phases: Aqueous formic acid/ammonium formate buffers and acetonitrile gradients under acidic and neutral conditions.
• Sample Preparation: Solid-phase extraction using ISOLUTE® C18(EC) and EVOLUTE® EXPRESS ABN for toxin cleanup prior to analysis.

Main Results and Discussion

Multi-mode ODS chromatography provided baseline separation for all five toxins with limits of detection in the 0.01–0.5 ppb range. HILIC mode yielded improved retention and peak shape for hydrophilic TTX. Optimized MRM transitions captured characteristic protonated, deprotonated and sodium-adduct ions. SPE pretreatment delivered recoveries of 66–83% for OA and DTX1, demonstrating effective cleanup.

Benefits and Practical Applications

• Achieved low-ppb detection limits across diverse toxin classes, surpassing traditional bioassays.
• Simultaneous analysis of lipophilic and hydrophilic toxins streamlines laboratory workflows.
• Method adaptability supports routine QA/QC and regulatory compliance in seafood safety.

Future Trends and Applications

Expanding the scope to additional shellfish toxins and integrating automated SPE cleanup will enhance throughput. Ongoing matrix effect evaluation and method standardization are expected to facilitate broader international adoption of LC-MS/MS toxin monitoring.

Conclusion

The combined use of multi-mode reversed-phase and HILIC separations with targeted SPE cleanup and MRM-based MS/MS delivers a robust, sensitive and selective platform for comprehensive marine toxin surveillance, advancing food safety practices.

References

Analytical methods referenced: AOAC 2005.06 and 2011.02; CODEX STAN 292-2008; Shimadzu LCMS-8050 and Nexera X2 instrument documentation.