Confirmation by LC–MS/MS of azaspiracids in shellfish from the Portuguese north-western coast

Abstract

The search for azaspiracids (AZAs) in shellfish on the Portuguese coast started in 2002, but the presence of these toxins could not be demonstrated until the summer of 2006. Analysis by liquid-chromatography–tandem mass spectrometry (LC–MS/MS) allowed the confirmation of AZA2 as a dominant compound, followed by AZA1, in blue mussel ( Mytilus galloprovincialis), common cockle ( Cerastoderma edule), clams ( Venerupis senegalensis, Ruditapes decussatus), razor clam ( Solen marginatus) and oyster ( Crassostrea spp). Traces of AZA3 were found only in blue mussel. Total levels of AZA1-3 determined in the whole flesh by LC–MS/MS ranged from 1.6 to 6.1 μg/kg. The finding of low levels of AZAs since 2002 suggests a low risk level when compared with the highest risks posed by diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP) toxins. However, the limited number of years studied might generate a misleading conclusion. The contamination with PSP is an example, as no contamination occurred for an extended period of time between 1996 and 2004, despite high levels having occurred outside this period. Thus, there appears overall a moderate likelihood of occurrence of AZAs in the range that may be relevant to consumers.