Determination of yessotoxins and pectenotoxins in shellfish by capillary electrophoresis-electrospray ionization-mass spectrometry

Abstract

Conditions for the determination of lipophilic marine toxins, such as yessotoxins and pectenotoxins (PTX)-6, were investigated with capillary electrophoresis coupled to mass spectrometry (MS) with an electrospray ionization source. After optimization, a simple and MS compatible alkaline volatile buffer solution of ammonium acetate was selected as background electrolyte, with isopropanol/water (80/20, v/v) sheath liquid modified with ammonium acetate used at the electrospray ionization (ESI) source. Previously to capillary electrophoresis (CE) separations, the application of an on-line sample pre-concentration approach based on field-amplified sample stacking was accomplished to increase sensitivity. As a result, the limits of detection provided by capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) were 0.02 µg ml⁻¹ (0.01 µg g⁻¹), which corresponded to 1.25 pg for yessotoxin and 0.25 µg ml⁻¹ (0.13 µg g⁻¹ and 13.25 pg on capillary) for PTX-6. Accuracy tests showed 97.7% recovery from spiked blank mussel samples that showed no significant matrix influence running under optimal conditions. Intermediate precision was close to 4% relative standard deviation (RSD) for the migration time, and an RSD of 7.5% for peak areas. The method was successfully applied to naturally contaminated seafood samples in which yessotoxins and pectenotoxins-6 were clearly determined. This work demonstrated the potential of CE-ESI-MS to be applied for a sensitive determination of lipophilic toxins from the marine environment as alternative to liquid chromatography-electrospray ionization-single quadrupole mass spectrometry (LC-ESI-MS) for this purpose.

Keywords:

• capillary electrophoresis
• mass spectrometry
• sample stacking
• yessotoxins
• pectenotoxins

Acknowledgements

The authors gratefully acknowledge: Dr Takeshi Yasumoto for providing standards of 45-OHYTX, PTX-6 and shellfish samples naturally contaminated; and Dr Paul McNabb for providing standards of YTX and shellfish samples naturally contaminated for this study. The doctoral fellowship of P. de la Iglesia was from European Union Project Ref.: EU-011-01.