Quantitative multiclass cyanotoxin analysis by paper spray mass spectrometry

Toxic cyanobacterial blooms are increasing in frequency in many parts of the world, and the toxins they can produce threaten both recreational use and drinking water supplies. Established analytical measurement techniques suffer from either high analysis costs and longer duty cycles, or lower accuracy and precision. Additionally, the chemical diversity of the different classes of cyanotoxins makes analysis by a single technique challenging. We present the development of a rapid multiclass method for cyanotoxin analysis using paper spray mass spectrometry requiring minimal sample preparation. A preliminary paper spray mass spectrometry (PS-MS) method developed on a triple quadrupole mass spectrometer yielded sensitive detection for microcystins, nodularin, and anatoxin with limits of detection below 3 μg/L, but suffered interference between phenylalanine and anatoxin. Subsequent method development using a custom-built PS source and high-resolution MS solved the anatoxin selectivity issue and provided typical detection limits between 0.3 and 1.6 μg/L for 6 microcystins, 2 anatoxins, and nodularin-R. Quantitative results for cyanobacteria culture extracts measured by PS-MS agreed well (typically ± 20 % bias) with results obtained with a reference LC-MS method. The presented methods are promising potential strategies for rapid cyanobacterial toxin screening, and could help address the growing need for rapid and simple techniques for high throughput cyanotoxin monitoring to mitigate exposure and reduce risks.