Hydrophilic interaction liquid chromatography-tandem mass spectrometry for quantitation of paralytic shellfish toxins: validation and application to reference materials
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Paralytic shellfish toxins (PSTs) are potent neurotoxins produced by marine dinoflagellates that are responsible for paralytic shellfish poisoning (PSP) in humans. This work highlights our ongoing efforts to develop quantitative methods for PSTs using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). Compared with the commonly used method of liquid chromatography with post-column oxidation and fluorescence detection (LC-ox-FLD), HILIC-MS/MS has the potential of being more robust, sensitive and straightforward to operate, and provides unequivocal confirmation of toxin identity. The main driving force for the present work was the need for a complementary method to LC-ox-FLD to assign values to shellfish tissue matrix reference materials for PSTs. Method parameters that were optimized included LC mobile and stationary phases, electrospray ionization (ESI) conditions, and MS/MS detection parameters. The developed method has been used in the detection and identification of a wide range of PSTs including less common analogues and metabolites in a range of shellfish and algal samples. We have assessed the matrix effects of shellfish samples and have evaluated dilution, standard addition and matrix matched calibration as means of mitigating them. Validation on one LC-MS/MS system for nine common PST analogues (GTX1-4, dcGTX2&3, STX, NEO, and dcSTX) was completed using standard addition. The method was then transferred to a more sensitive LC-MS/MS system, expanded to include five more PSTs (C1&2, dcNEO and GTX5&6) and validated using matrix matched calibration. Limits of detection of the validated method ranged between 6 and 280 nmol/kg tissue using standard addition in extracts of blue mussels, with recoveries between 92 and 108%. Finally, this method was used in combination with the AOAC Official Method based on LC-ox-FLD to measure PSTs in a new mussel tissue matrix reference material.
KeywordsHydrophilic interaction liquid chromatography Mass spectrometry Algal toxins Paralytic shellfish poisoning Reference material
The authors acknowledge funding from the Canadian Food Inspection Agency (CFIA) and the UK Food Standards Agency, technical assistance from Nancy Lewis, Ruth Perez, Stephen Chung, Diane Marciniak, Sheila Crain, Tobias Karakach and Elliott Wright. Emanuel Hignutt from the Alaska Department of Environmental Conservation is acknowledged for his support and early adoption of the described methodology. The authors would also like to thank Sciex for supporting the validation work on the QTRAP 5500.
Compliance with ethical standards
The research did not involve human participants or animals.
Conflict of interest
The authors declare that they have no conflict of interest.
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