Development of Analytical Methods for Multiple Phycotoxins in Fish Plasma

Certain harmful algal blooms (HABs) produce phycotoxins, which can be toxic to animals and to humans through seafood consumption. Data are currently lacking regarding the accumulation of phycotoxins in fish species. Quick and reliable methods are needed to assess toxin load in various upper trophic level fish species, both for diagnostics in fish mortality and prevention of human poisoning events. In this study, a method was developed for the extraction and cleanup of phycotoxins from plasma of juvenile sandbar sharks (Carcharhinus plumbeus) using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Three cleanup methods were evaluated by QuEChERS, a dispersive SPE (d-SPE) method, and two national laboratory standards, solid phase extraction (SPE) and Hexane wash. The percent recovery (%R) of each was calculated across 14 different phycotoxins, both hydrophilic and lipophilic. Using generalized linear models, QuEChERS d-SPE %R was found to be similar to the national laboratory standard cleanup methods (SPE and Hexane wash). QuEChERS d-SPE had the highest %R at 100.7 ± 13.5% along with the most time efficient and second most cost-effective cleanup method of those tested. QuEChERS d-SPE was then validated using plasma from two species of bony fishes: Atlantic striped bass (Morone saxatilis) and blue catfish (Ictalurus furcatus) and optimized for all phycotoxins. Averaged across all three species, QuEChERS d-SPE had a %R of 94.8 ± 14.4%. This method provides a nonlethal way of sample collection to set a baseline of phycotoxin exposure in fish and illustrates that differences in sample cleanup between species may be necessary, which can help guide future monitoring, management, and public health efforts.