Studies on azaspiracid biotoxins. III. Instrumental validation for rapid quantification of AZA 1 in complex biological matrices

Azaspiracids are neurotoxins produced by marine algae that have been detected in harvested mussels since 1995. They pose a significant threat to human health through the consumption of contaminated shellfish, and negatively impact the economy of areas where shellfish are harvested and processed. Regulatory agencies are beginning to advocate instrumental assays over traditional mouse bioassay methods. The development and validation of an assay method for AZA 1, the predominant azaspiracid toxin, and the production of a calibration standard and reference material will therefore be vital for quality control in monitoring laboratories worldwide. This report demonstrates a rapid and reproducible liquid chromatography/mass spectrometry (LC/MS) method for separation of all twelve known azaspiracids. Using a triple-quadrupole mass spectrometer, ultra-high sensitivity was obtained at the low-femtogram level injected on-column. At the same time, a linear response of three orders of magnitude was observed. We compared the results with those measured on an ion-trap mass spectrometer. The triple-quadrupole instrument was more sensitive, reliable and reproducible than the ion-trap instrument. The detection limit obtained on the ion-trap mass spectrometer was ten times higher than that obtained on the triple quadrupole. During the study, a new azaspiracid analog (AZA 7c) was discovered.