Comparison of Two Passive Samplers for Hydrophilic and Lipophilic Phycotoxins and Expansion of Analytical Methods for Quantification Using UPLC-MS/MS

The co-occurrence of phycotoxins produced by harmful algal blooms is becoming more frequent. To combat this problem, monitoring programs that can track and quantify a wide range of hydrophilic and lipophilic phycotoxins are required. A 24 h, bench-scale study was conducted to provide an initial comparison of apparent sorption and extraction recovery for 24 freshwater and marine phycotoxins from two passive samplers under controlled artificial seawater conditions. Modifications were made to previously published ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) methods to capture all phycotoxin analytes of interest in two injections. This analytical method was also evaluated alongside extraction methods for a commonly used passive sampler, a solid phase adsorption toxin tracker (SPATT), and a novel passive sampler, the composite integrated passive sampler (CIPS). SPATT contained a lipophilic resin, Diaion® HP20, whereas the CIPS is a continuous sheet with hydrophilic and lipophilic regions aimed at allowing for adsorption across a wider range of phycotoxins. A single-step extraction procedure was tested for both samplers to determine apparent extraction recoveries for all 24 phycotoxins. The CIPS seemed to produce overall higher apparent extraction recoveries of analytes, but the receiving phase generally sorbed less ng of phycotoxin during the experimental period than SPATTs and matrix effects were present. Across all lipophilic and hydrophilic phycotoxins, SPATT sorbed more than 90% of each phycotoxin from the seawater within 24 h, for all but four phycotoxins. The CIPS, however, sorbed less of each, but still more than 50% in artificial seawater for all but three phycotoxins. When considering extraction efficiency, SPATT may be better suited for hydrophilic phycotoxins, while the extraction method for CIPS appeared more efficient for lipophilic compounds, but further investigations are required to investigate potential matrix effects. The utility of the novel CIPS was preliminarily demonstrated in the laboratory, with seemingly relatively improved performance for particular phycotoxin classes (Azaspiracids, Dinophysistoxins/Pectenotoxins, Microcystins, and Brevetoxin) as compared to SPATT. The expanded UPLC methods and CIPS must be trialed in the field next to determine their applicability to monitoring, research, and management. The benchtop work, however, already suggests that users should consider the full range of phycotoxins present at an environmental site and create sampling schemes appropriate for their region given the different sorption and extraction efficiencies of these two samplers.