First evidence of MC-HtyR associated to a Plankthothrix rubescens blooming in an Italian lake based on a LC-MS method for routinely analysis of twelve microcystins in freshwaters

摘要

A recent Italian regulatory level for microcystins (MCs) in drinking water was set at 1.0 mu g/L, intended as the sum of all variants that can be determined using commercially available standards. A selective multi-residue method for analyzing twelve variants of MCs (MC-RR, MC-YR, MC-LR, MC-LA, MC-LW, MC-LF, MC-LY, [D-Asp(3)]-MC-RR, [D-Asp(3)]-MC-LR, MC-WR, MC-HiIR, MC-HtyR) in surface and drinking waters was optimized and validated in accordance with the Italian implementation of the Drinking Water Directive 98/83/EC. The proposed method was robust as proved by using nodularin as quality control, with inter-matrices reproducibility better than 17% and matrix effects not significantly dependent among different water samples. LODs were in the range of 0.003-0.030 mu g/L for all the analytes, allowing the quantitative analysis of selected MCs at levels lower than 1/10 of the proposed new Italian parametric values. The method was tailored for the routine analysis of MCs in the frame of risk management related to MCs production during toxic algal blooms.