Determination of yessotoxins and pectenotoxins in shellfish by capillary electrophoresis-electrospray ionization-mass spectrometry.
Résumé
Conditions for the determination of lipophilic marine toxins, such as yessotoxins and pectenotoxins-6 were investigated with capillary electrophoresis coupled to mass spectrometry with an electrospray ionization source. After optimization, a simple and MS compatible alkaline volatile buffer solution of ammonium acetate was selected as background electrolyte, while a sheath liquid consisted in isopropanol/water (80/20, v/v) modified with ammonium acetate was used at the ESI source. Previously to CE separations, the application of an on-line sample preconcentration approach based on field-amplified sample stacking was accomplished to increase the sensitivity. As a result, the limits of detection provided by 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% of recovery from spiked blank mussel samples which revealed no significant matrix influence running under optimal conditions. Intermediate precision was close to 4% RSD for migration time while 7.5% was obtained for peak areas. The method was successfully applied to naturally contaminated seafood samples, in which yessotoxins and pectenotoxins-6 were clearly determined. Thus, this work demonstrates the potential of CE-ESI-MS to be applied for a sensitive determination of lipophilic toxins from the marine environment as alternative to LC-ESI-MS for this purpose.
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