Genoa 2005 outbreak: determination of putative palytoxin in mediterranean Ostreopsis ovata by a new LC/MS method

During Summer 2005, symptoms of rhinorrea, cough, fever, bronchoconstriction with mild dyspnea were observed in about 200 people exposed to marine aerosols on the beach of Genoa (Italy). The toxic outbreak was correlated with the co-occurrence of an unusual proliferation of the tropical microalga Ostreopsis ovata. Some Ostreopsis strains are proven to produce analogues of palytoxin. Thus, the need arose to develop an analytical method for detecting palytoxin in order to investigate whether the O. ovata blooming during the Genoa event was producing the toxin. A new LC/MS method for palytoxin was set up on a turbo ionspray (TSI)- triple quadrupole MS instrument operating in selected ion monitoring (SIM) and multiple reaction monitoring (MRM) acquisition modes (positive ions). The minimum detection levels for matrix-free toxin on-column, which were estimated to be 17 pg (3.4 ng/mL) and 29 pg (5.8 ng/mL) in MRM and SIM mode, respectively, make the method suitable for monitoring program. Application of the method to the analysis of a plankton sample collected along Genoa coasts during the toxic event, demonstrated for the first time the presence of a putative palytoxin in Italian waters and pointed to this toxin as the causative agent of the Genoa outbreak.