Stability and Recovery of Palytoxin and Ovatoxin‑a

Palytoxin and ovatoxins belong to a class of marine toxins identified in soft corals and microalgae, Palythoa spp. and Ostreopsis spp., respectively. Several documented events have resulted in human exposure to aerosolized toxins that led to significant respiratory distress. It has been reported that processing of samples containing palytoxin and ovatoxin during analysis can lead to significant analyte recovery issues due to a variety of parameters. In this study, systematically designed experiments, monitored by LC-MS/MS, were used to evaluate palytoxin and ovatoxin-a stability and recovery, and the effects of pH, solvent composition, and vial contact surface. Significant losses of palytoxin and ovatoxin-a were observed when drying highly aqueous solutions in glass, which were reduced with the use of a polypropylene contact surface and the addition of bovine serum albumin and phosphate-buffered saline. The results showed that palytoxin analogues should be maintained in solutions containing greater than 50% organic solvent, such as methanol, and in a pH range of 5-8 in order to minimize losses or degradation. The recovery of ovatoxin-a was lower than for palytoxin in several experiments, indicating that the structural differences between these analogues may affect solubility or stability. This work provides insight into palytoxin and ovatoxin-a handling, and will help improve analytical measurements, handling during toxicology studies, and minimize losses during isolation protocols for the development of reference materials.