Lithium iodide hydrate

Formic acid (98–100%), acetic acid (96%), and ammonia (25%) were purchased from VWR, Amsterdam, the Netherlands. Acetonitrile (Ultra LC-MS), methanol (Ultra LC-MS), and water (Ultra LC-MS) were purchased from Actu-All, Oss, the Netherlands. Lithium iodide hydrate (98%) and lithium chloride (>99%) were purchased from Sigma-Aldrich, Zwijndrecht, the Netherlands. PlTX (>90%) was purchased from Wako, Osaka, Japan.
Blank shellfish samples used for method validation were collected in 2017 from several shellfish production areas in the Netherlands. Contaminated sample extracts containing pPlTX and OVTXs were a gift from Carmela Dell’aversano, University of Naples Federico II, Napoli, Italy.

The LiI/I₂ solutions were prepared using Lithium Iodide, LiI (Sigma-Aldrich: Lithium Iodide Hydrate, 223816, St. Louis, MO, USA), in Milli-Q Water and were saturated with Iodine, I₂ (Sigma-Aldrich: Iodine, 229695). Nafion 212 (Nafion Store: N212, ion exchange capacity 0.95 to 1.01 meq g ${}^{-1}$ and thickness of 50 $\mathsf{\mu }$ m in dry conditions) was pre-treated as described earlier [36 (link)]. First it was boiled in 3 wt% H₂O₂ for 1 h, washed in boiling in milli-Q water for 10 min, boiled in 0.05 M sulfuric acid for 30 min, and finally rinsed several times in boiling water. After pre-treatment the membranes were stored in 1 M LiCl until use.