Ultra-Trace Analysis of Cyanotoxins by Liquid Chromatography Coupled to High-Resolution Mass Spectrometry

Abstract

The increasing frequency of episodes of harmful algal blooms of cyanobacterial origin is a risk to ecosystems and human health. The main human hazard may arise from drinking water supply and recreational water use. For this reason, efficient multiclass analytical methods are needed to assess the level of cyanotoxins in water reservoirs and tackle these problems. This work describes the development of a fast, sensitive, and robust analytical method for multiclass cyanotoxins determination based on dual solid-phase extraction (SPE) procedure using a polymeric cartridge, Oasis HLB (Waters Corporation, Milford, MA, USA), and a graphitized non-porous carbon cartridge, SupelcleanTM ENVI-CarbTM (Sigma-Aldrich, St. Louis, MO, USA), followed by ultra-high-performance liquid chromatography high-resolution mass spectrometry (SPE-UHPLC-HRMS). This method enabled the analysis of cylindrospermopsin, anatoxin-a, nodularin, and seven microcystins (MC-LR, MC-RR, MC-YR, MC-LA, MC-LY, MC-LW, MC-LF). The method limits of detection (MLOD) of the validated approach were between 4 and 150 pg/L. The analytical method was applied to assess the presence of the selected toxins in 21 samples collected in three natural water reservoirs in the Ter River in Catalonia (NE of Spain) used to produce drinking water for Barcelona city (Spain).

Cyanobacteria and their secondary metabolites in three freshwater reservoirs in the United Kingdom

“…Cyanopeptides were extracted and pre-concentrated according to a recently validated method [33]. Briefly, 300 mL of each freshwater sample was sonicated in an ultrasonic bath (30 min, 200 W, 60 Hz) to lyse cells and release intracellular cyanopeptides.…”

“…Concentrations were only reported when the peak area was above the limits of quantification (LOQs) of the respective regression model. Recoveries from the sample preparation procedure were previously assessed for anatoxin-a, cylindrospermopsin, and several microcystins in the range of 50-87% [33]. The analysis sequence spanned 3 days, with a nanopure water-based calibration curve analysed midway through and a matrix-matched calibration curve analysed at the end of the sequence.…”

A data independent acquisition all ion fragmentation mode tool for the suspect screening of natural toxins in surface water

“…Here the tentative candidate microcystin LR was detected with the typical molecular ion at m/z= 995.5545. The doubly charged ion at 498.2822 m/z was also encountered at T r 9.12 min with the typical higher intensity respect to the molecular ion [13] . Finally, the MS/MS spectra revealed the presence of the typical fragment at 135.0803 m/z which is the exact mass of the ADDA fragment part of all the microcystins structure.…”

Multiclass cyanotoxin analysis in reservoir waters: Tandem solid-phase extraction followed by zwitterionic hydrophilic interaction liquid chromatography-mass spectrometry

“…In this manner, it was possible to extract the target cyanotoxins from reservoir water samples by means of a single sample loading step and the use of a single eluent in the elution step. This makes the process much more efficient, in contrast with previous studies where different procedures are employed for each family of cyanotoxins [21,49,50]. Furthermore, this is a novel work as it includes the joint extraction of NPA isomers with other cyanotoxins from different families such as microcystins, nodularin, anatoxin and cylindrospermopsin.…”

“…However, the literature often describes one SPE procedure for each family of cyanotoxins or separate elutions of the cartridges [21,49,50] turning the extraction into a time-consuming and tedious process. To the best of our knowledge, the extraction of a mixture consisting of cyclic peptides and alkaloids in combination with the NPA isomers has not been developed previously.…”