Saxitoxin (PSP) Rapid Test Kit for Shellfish – Lateral Flow

Saxitoxins (STXs) are naturally occurring alkaloids produced by some marine dinoflagellates and by strains of various species of freshwater cyanobacteria. Saxitoxin is one of the prevalent paralytic shellfish toxins (PSTs). It belongs to a family of potent neurotoxins with a molecular weight around 300 Da. Saxitoxin and its derivatives are alkaloids composed of a tetrahydropurine ring system with a highly polar guanidinium group. Due to their significant toxicity, saxitoxins are closely monitored in marine environments where they can accumulate in the food chain during harmful algal blooms (HABs). The regulatory limit for PSP toxins in shellfish is 800 µg saxitoxin-dihydrochloride equivalents per kg of shellfish meat (80 µg per 100 g), used by the US FDA and the EU. The kit responds most strongly to saxitoxin. In development testing, neosaxitoxin (neoSTX), GTX5 and GTX6 gave no consistent response; gonyautoxins GTX2/3, and to a lesser extent GTX1/4, gave a partial response in one of two experiments. A result below 800 ppb therefore does not rule out total PSP toxicity above the limit. Positive screens should be confirmed by ELISA, HPLC or another conventional method.