Quantification of Multi-class Cyanopeptides in Swiss Lakes with Automated Extraction, Enrichment and Analysis by Online-SPE HPLC-HRMS/MS

Abstract

The frequency and intensity of cyanobacterial blooms continue to increase in freshwater systems across the globe. Cyanobacteria can release toxins and several bioactive secondary metabolites and analytical methods are needed to effectively assess their concentrations in surface waters. Since blooms can evolve rapidly in parts of a lake, high resolution of spatial and temporal sampling increases the complexity of monitoring efforts. Here, we present the validation of an automated, online-solid phase extraction (SPE) high performance liquid chromatography (HPLC)-high resolution tandem mass spectrometry (HRMS/MS) method. This online-SPE HPLC-HRMS/MS method enables quantitative monitoring of surface waters for 17 cyanobacterial peptides (cyanopeptides), spanning 5 distinct cyanopeptide classes, including: microcystins, anabaenopeptins, nodularins, cyclamides and cyanopeptolins. The method can quantify these cyanopeptides in the low ng/L-range with high accuracy (85-116%) and low relative matrix effects (<25%). We demonstrated its application to Swiss lake waters (Zürichsee, Hallwilersee, Greifensee), which also highlighted the value of adding cyanopeptides beyond common microcystins when monitoring surface waters for cyanobacteria.