An investigation into solid phase adsorption toxin tracking (SPATT) for the detection of domoic acid, the amnesic shellfish poison, in seawater

Previously proposed as a tool to facilitate monitoring of lipophilic shellfish toxins (LSTs), solid-phase adsorption toxin tracking (SPATT) was assessed for its capability to adsorb and recover domoic acid (DA), an amnesic shellfish toxin (AST) responsible for site closures in Scottish waters. SPATT bags containing SP700 resin beads were deployed in Loch Ewe (Scotland) on a weekly basis in conjunction with sampling of phytoplankton and local bivalve shellfish. During four sampling periods throughout summer 2009, an automated water sampler was deployed at Loch Ewe, flushing daily seawater through SPATT cartridges containing SP-700 resin and collecting water samples for phytoplankton identification. SPATT resin samples were extracted and analysed by LC-MS/MS and ELISA. Although no direct correlation could be drawn between the concentration of DA in SPATT extracts and the phytoplankton community present in water samples, significant variations of toxin concentration could be observed between sampling periods. Importantly, the detection of DA in all SPATT cartridges proved that although a limited amount of DA could only be desorbed from the resin after initial adsorption, the quantity recovered was enough to show daily variations of DA concentration in seawater. Results suggest that SPATT cartridges may possibly be used as an early warning tool to inform shellfish farmers of an incoming or declining toxic event and could potentially help better understand AST events.