Abstract
Ultra-performance hydrophilic interaction liquid chromatography tandem mass spectrometry system (UP-HILIC–MS/MS) was used in multi-toxin analysis of paralytic shellfish toxins (PSTs) and tetrodotoxins (TTXs) in sample matrices from bivalve molluscan species commercially produced for human consumption in Sweden. The method validation includes 17 toxins of which GTX6 and two TTX analogues, TTX and 4,9-anhydroTTX, were previously not analyzed together with hydrophilic PSTs. 11-deoxyTTX was monitored qualitatively with a non-certified reference standard. The performance of the method was evaluated for selectivity, repeatability, and linearity by analyzing spiked samples which generated linear calibration curves across the concentration ranges used (R2 > 0.99). The in-house reproducibility (RSD) was satisfactory including the LOD and LOQ for both PST and TTX toxins being far below their regulatory action limits. The major advantage of the method is that it allows direct confirmation of the toxin identity and specific toxin quantification using a derivatization-free approach. Unlike the PST-chemical methods used in routine regulatory monitoring until now for food control, the UP-HILIC-MS/MS approach enables the calibration set-up for each of the toxin analogs separately, thereby providing the essential flexibility and specificity in analysis of this challenging group of toxins. The method is suitable to implement in food monitoring for PSTs and TTXs in bivalves, and can serve as a fast and cost-efficient screening method. However, positive samples would, for regulatory reasons still need to be confirmed using the AOAC official method (2005.06).
Highlights
Marine biotoxins, such as paralytic shellfish toxins (PSTs) and tetrodotoxins (TTXs), accumulate in bivalve mollusks during their filter feeding in marine environment where other marine species responsible for generation of these toxins are present
The most common bivalve species commercially produced in Sweden, blue mussels (Mytilus edulis), (Ostreabivalve edulis),species and cockles (Cerastoderma edule) were used as three(Mytilus representative
The TTX was included in a multi-toxin UP-HILIC-MS/MS method together with the PST group of toxins and, with the support of the previously published thorough method development for PST using HILIC, here presented as a tool qualified to include in the official monitoring of bivalves in the European food control
Summary
Marine biotoxins, such as paralytic shellfish toxins (PSTs) and tetrodotoxins (TTXs), accumulate in bivalve mollusks (e.g., mussels and oysters) during their filter feeding in marine environment where other marine species responsible for generation of these toxins are present (phytoplankton [1] or marineToxins 2020, 12, 452; doi:10.3390/toxins12070452 www.mdpi.com/journal/toxinsToxins 2020, 12, 452 bacteria in symbiosis with other organisms [2,3,4,5,6]). The changing climate with longer periods of elevated temperatures in combination with the presence of nutrients create the conditions for new events in the marine environment These changes can be linked to proliferation of phytoplankton (harmful algae blooms, HABs) [17,18,19] resulting in occurrence of previously known toxins at new places as well as occurrence of new analogs and variants of marine biotoxins [20,21,22,23]. Such emerging toxins pose serious hazard for public health and destabilizes the aqua culture of bivalves
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