Title : Matrix effect in the analysis of paralytic shellfish toxins and tetrodotoxins: Implication for risk assessment
Abstract:
Paralytic Shellfish Toxins (PSTs) and Tetrodotoxins (TTXs) are potent natural neurotoxins with different chemical structures but similar poisoning symptoms and mechanisms of action. They block nerve signal transmission by binding to voltage-gated sodium (Na⁺) channels, leading to nerve and muscle paralysis. PSTs are produced by marine dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium, and accumulate in filter-feeding bivalve molluscs. Originally associated with pufferfish, TTXs are synthesised by symbiotic bacteria such as Pseudoalteromonas and Vibrio, and have recently been detected in gastropods, echinoderms, and other marine organisms. Climate change has altered the geographical distribution of these toxins; notably, TTXs have been reported in European molluscs previously unaffected, raising new concerns for food safety and public health. As part of the risk assessment of human exposure to marine biotoxins, it is pivotal to develop analytical methods that ensure reliable and robust quantitative performance, to provide accurate information on toxins occurrence in food products and support consumer exposure evaluation.
In recent years, several LC-MSMS methods have been developed as alternatives to the official LC-FLD method for PST analysis. One of the main issues is the matrix effect, which is the primary source of error in estimating the toxic equivalents of these substances. The aim of this work was to quantify and evaluate the Matrix Effect % (ME%) on target marine species involved in PST and TTX bioaccumulation. Molluscs, gastropods, and echinoderms were considered, and results showed that quantitative outputs are strongly influenced by ME%. The effect is strictly matrix-dependent due to different composition in terms of proteins, lipids, polysaccharides, and other minor components. This was particularly evident for the most toxic congeners (Saxitoxin, Neosaxitoxin, Decarbamoylsaxitoxin and Gonyautoxin 1 & 4) with ME% values ranging from −80% (ion suppression) to +190% (ion enhancement). In conclusion, a comprehensive understanding and quantification of ME% is crucial for risk assessment. Inadequate control of matrix effects may result in inaccurate quantification of contaminants, compromising exposure assessments and undermining the reliability of public health protections.
