FIRST DETERMINATION OF CYLINDROSPERMOPSIN IN DRINKING WATER CHAIN OF VICO LAKE WITH SPE-LC-MS/MS

The incidence of cyanobacterial harmful algal blooms (CHABs) is increasing in Italy and worldwide. Cyanotoxins cause a substantial amount of human and animal poisoning from exposures in drinking-source and potable waters. Cylindrospermopsin (CYN) is a hepatotoxin and nephrotoxic cyanobacterial produced by Cylindrospermopsis raciborskii and other cyanobacteria such as Umezakia natans, Aphanizomenon ovalisporum and Raphidiopsis curvata; it is also considered a potential carcinogen. Cylindrospermopsin in an alkaloid compound characterized by with a guanidico tricyclic group combined with hydroxymethyl-uracil. This study describes the first occurrence of cylindrospermopsin during a serious bloom of cyanobacterium Aphanizomenon ovalisporum with maximum algal density exceeding 3.5 million cells/L observed since the beginning of 2010 in Vico Lake (Lazio, Italy). The water of this lake was even used for human consumption, so it was necessary started a monitoring activity for the identification and the quantification of the cyanobacteria presents in the water and the cianotoxins eventually produced. The samples of raw, treated and drinking water from Vico Lake were monthly collected over a seven years-period with simultaneous determination of cyanotoxins concentration and algal population. An analytical protocol based on solid phase extraction followed by detection with liquid chromatography–tandem mass spectrometry (SPE-LC-MS/MS) has been employed and optimized for the determination of the cylindrospermopsin in the water samples. For determination of cylindrospermopsin, chromatographic gradient was employed, using acetonitrile (component A) and water (component B) as mobile phases, both containing 10 mM formic acid, by using a Dionex Ultimate 3000 HPLC system (Dionex Corporation, Sunnyvale, CA, USA) equipped with a Zorbax SB-Aq (4,6 mm ID x 150 mm, 5 μm, Agilent). MS analyses were carried out using an API 3000 triple-quadrupole mass spectrometer (Applied Biosystem) operating in positive ionization mode and Multiple Reaction Monitoring acquisition. That method was proved to be robust and very sensitive, with LOD of 0,001 μg/L. Cylindrospermopsin was sporadically observed through the entire drinking water chain, in raw, treated and distributed water from Vico basin, with maximum concentration of 0.552, 0.187 and 0.167 μg/L respectively.