Multi-residue Ultra Performance Liquid Chromatography-High resolution mass spectrometric method for the analysis of 21 cyanotoxins in surface water for human consumption

The presence of cyanobacteria and their toxins in water used as drinking water or for recreational purposes may represent a risk for human health. This work describes the development of an advanced analytical method for simultaneous determination of 21 cyanotoxins (including Microcystins, Cyanopeptolins, Anabaenopeptins and Microginins) in drinking water based on Ultra Performance Liquid Chromatography coupled with a Q-TOF mass spectrometer. Water samples, spiked with Nodularin as internal standard at 1 μg/L, were extracted using Carbograph 4 SPE cartridge and 10 μL of the extracted sample were injected into the UPLC-HRMS/MS system. Analytes separation was obtained using a UPLC C18 column, acetonitrile and water as mobile phases, both containing 10 mM formic acid, and operating in positive ionization mode and sensitivity mode. The method has been proven to be robust, precise and accurate with recovery percentages above 85% and with relative standard deviations ≤16% and LODs between 0.002 and 0.047 μg/L, fitting for the intended purposes at the concentrations of interest. This method was applied during a monitoring activity in an Italian volcanic lake in Viterbo (Lazio Region, Italy), due to a severe algal proliferation in January 2018–March 2019 period and for the assessment of cyanobacteria proliferation risk and of cyanotoxin production in drinking water chain.