LC-MS Profiling of DSP Toxins in Shellfish Samples from the 2006 Scottish DSP Monitoring Programme

Background:<BR> Filter feeding bivalve molluscs, such as mussels, can accumulate toxic metabolites produced by marine dinoflagellates (Dinophysis). These toxins can be transferred to humans during consumption of the molluscs, causing DSP. For the purposes of safeguarding public health, regular monitoring for these toxins is carried out around Scotland. The toxins associated with DSP can be divided into three groups based on their chemical structure; (i) the acidic okadaic acid (OA) and its derivatives dinophysistoxins (DTXs), pectenotoxins (PTXs), and yessotoxin (YTX) and its analogues. Other lipid-soluble toxins such as spiroimines [e.g., azaspiracids (AZAs), gymnodimine (GYM) and spirolides (SPXs)] may also be present. The project aims to identify the toxin profiles prevalent around Scotland, to provide data to support the Scottish Monitoring Programme. <P>
Research Approach:<BR> Samples that have been shown to be positive for DSP toxins from the 2006 Scottish Monitoring Programme will be selected for analysis by Liquid Chromatography - Mass Spectrophotometry (LC-MS) to identify the different toxin analogues present. Samples will be selected to attempt to obtain information on the geographical variation of toxin profiles.
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Results and findings:<BR>This research project aimed to determine the concentrations and toxin composition of DSP toxins in selected mussel samples from the Scottish 2006 Diarrhetic Shellfish Poisoning (DSP) monitoring Programme.
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Concentrations (ìg/kg) of lipid soluble toxins were measured in common mussels sampled between 20th June and 18th October 2006. Analogues from four toxin groups; Okadaic Acid (OA), pectenotoxins (PTX), Azaspiracid (AZAs) and spirolides were detected throughout the study period. Toxins belonging to the yessotoxin and gymnodimine groups were not detected in any of the samples analysed.
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Free OA was evident in all but one of the sample extracts analysed with concentrations ranged from 15 to 383 ìg/kg. Free PTX were also detected in a number of samples with levels of the parent PTX2 toxin ranging from <LOQ to 418 ìg/kg. Analogues of AZA were detected in 12 out of the total 33 samples analysed during the course of this study, although the distribution of these toxins was less widespread in comparison to the OA or PTX groups. Overall, concentrations of AZA were found to be <10 ìg/kg. Trace levels (<1.5 ìg/kg) of the parent toxin of desmethyl spirolide C group (SPX1) was evident at three locations around Scotland.
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At three shellfish production sites (Drovinish in Loch Roag, and Clift Sound and Ronas Voe in Shetland), toxin concentrations were examined over the 6-month period of the study to identify possible temporal trends over discrete sampling periods. General trends in toxin profile and levels of contamination were detected in these sites.
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The study highlighted that comprehensive Liquid Chromatography-Mass Spectrometry (LC-MS) analyses has proved to be a robust and a powerful tool to describe the spatial and temporal distributions of lipid-soluble toxin profiles in mussels from selected Scottish shellfish production sites during 2006. Temporal trends of okadaic acid and dinophysistoxins, at selected locations, indicated that these toxins could persist for up to several months.
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This study has given the Agency a valuable insight in to the profiles of lipophillic toxin analogues that were present bivalve molluscs harvested from Scottish waters during 2006. The study has also shown the value of LC-MC as a tool for determining the profiles of these toxins in mussel samples.

<p>Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/&quot; target="_blank">Food Standards Agency Research webpage</a>.