Abstract
Spirulina (Arthrospira spp.) and klamath (Aphanizomenon flos-aquae) are widely consumed cyanobacteria-based food supplements valued for their nutritional and health-promoting properties. However, these products are susceptible to contamination by cyanotoxins, which are potent toxins produced by co-occurring cyanobacteria that may pose health risks to consumers. In this study, we applied an integrated targeted and suspect screening approach to comprehensively assess the presence of cyanotoxins in commercial spirulina- and klamath-based food supplements. Targeted analysis was performed using UHPLC-QqQ under dynamic multiple reaction-monitoring conditions optimized for the determination of twelve cyclic peptide cyanotoxins. Suspect screening was conducted using high-resolution mass spectrometry (HRMS) with a Q-Orbitrap analyser, applying a specific workflow to detect additional related compounds lacking analytical standards. The method enabled the detection and identification of multiple cyanotoxins, including microcystins, nodularin, and anabaenopeptins. The combination of targeted and suspect workflows allowed for a broader coverage of potential related cyanotoxins. Several cyanotoxins were detected in a klamath-based supplement, with high concentrations of microcystin-RR, while additional variants were identified through suspect screening. These findings highlight the need for routine monitoring and stricter regulatory oversight of cyanobacteria-based supplements to ensure consumer safety.