| Abstract | Rationale: anatoxins (ATXs) are a potent class of cyanobacterial neurotoxins that are increasingly problematic in drinking water reservoirs and recreational water bodies worldwide. Because of their high polarity and low molecular weight, analysis of ATXs is challenging and they can be considered underreported compared with other classes of cyanobacterial toxins. Improved screening methods are therefore needed to effectively assess their occurrence and concentrations in the environment.
Methods: a rapid screening method was developed for ATXs in cyanobacteria using direct analysis in real time – high resolution mass spectrometry (DART–HRMS), requiring < 2 min per sample for triplicate analysis. The developed method was evaluated for its quantitative capabilities, applied to the screening of 30 cyanobacteria culture samples for the presence of anatoxin‐a, homoanatoxin‐a and dihydroanatoxin‐a, and compared with a more typical liquid chromatography–HRMS method.
Results: excellent linearity was observed in the analysis of a matrix‐matched calibration curve by DART–HRMS, with ionization suppression of about 50% and relative standard deviations between replicate analyses of approximately 30%. Limits of detection for both anatoxin‐a and homoanatoxin‐a were estimated as 1 ng/mL. Excellent agreement was observed between DART‐HRMS and LC/HRMS with all ATX‐producing cultures correctly identified and only one false positive culture by DART‐HRMS.
Conclusions: DART‐HRMS shows excellent promise for the rapid, quantitative screening of ATXs in cyanobacteria and could be expanded in the future to include the analysis of field samples and drinking water, as well as additional ATX analogues. |
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