Development of high sensitivity and separation detection method for ciguatoxin analogues by LC/MS

Importance of the Topic

Ciguatera fish poisoning is a widespread food safety concern driven by trace levels of ciguatoxin analogues produced by marine dinoflagellates. As neurotoxic polyether compounds, these toxins can cause severe illness even at sub microgram per kilogram concentrations. Regulatory bodies recommend control limits as low as 0.01 micrograms per kilogram equivalent of CTX1B. High sensitivity analytical techniques are essential to ensure seafood safety and support public health monitoring.

Objectives and Study Overview

This work aimed to develop a highly sensitive and selective liquid chromatography tandem mass spectrometry method for nine ciguatoxin analogues. The study optimized mobile phase formulation with alkali metal additives to enhance ionization, evaluated collision energies for key adducts, and validated performance metrics including limits of quantification, reproducibility, and accuracy.

Instrumentation

• UHPLC system: Nexera X3 UHPLC
• Mass spectrometer: LCMS-8060NX triple quadrupole MS

Methodology and Instrumentation

The UHPLC separation employed a reverse-phase column with gradient elution using ammonium formate buffer and organic solvents. Trace amounts of sodium or lithium salts were added to the mobile phase to promote formation of [M+Na]+ or [M+Li]+ adducts. MS/MS detection was set to multiple reaction monitoring of adduct ions with optimized collision energies determined for each toxin analogue.

Main Results and Discussion

• Formation of lithium adducts improved signal-to-noise and sensitivity compared to sodium or ammonium adducts for several analogues.
• Optimized collision energies produced robust MRM transitions with linear calibration curves over low nanogram per milliliter ranges.
• Limits of quantification ranged from 0.0004 to 0.0012 micrograms per kilogram when extracting 5 grams of tissue.
• Chromatographic separation was enhanced using Li-added mobile phases, resolving closely eluting isomers and epimers.

Benefits and Practical Applications

This method enables routine screening of ciguatoxins at regulatory threshold levels using general-purpose LC-MS/MS platforms. It supports food safety laboratories conducting quality control of seafood and research on toxin distribution in marine ecosystems.

Future Trends and Potential Uses

Advances may include application of high-resolution mass spectrometry for structural elucidation of novel ciguatoxin variants, integration with automated sample preparation workflows, and adaptation to on-site toxin monitoring kits. Emerging bioinformatic tools can streamline data analysis and cross‐laboratory standardization.

Conclusion

The developed LC/MS/MS method with lithium and sodium cationization achieves sensitivity beyond regulatory requirements for nine ciguatoxin analogues. It delivers reliable quantification, improved separation, and broad applicability on common analytical platforms.

Reference

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5 Oshiro N Mar Sci Eng 2023 11 242