Quantification and profiling of lipophilic marine toxins in microalgae by UHPLC coupled to high-resolution orbitrap mass spectrometry

Through global shipping and trade, mankind has inadvertently spread marine organisms to such an extent that many are now considered cosmopolitan. Further aggravated by changes in the foodweb structure (overfishing), eutrophication and climate change, this has led to a substantial increase in the occurrence of harmful algal blooms (HABs). Next to the large potential for environmental damage, these recurring events have become a global public health concern as many species produce potent marine toxins that may lead to shellfish poisoning. To ensure food safety, the mouse bioassay has long been used to screen seafood for the presence of these toxins. Due to ethical concerns, however, this test is now being replaced by alternative chemical analyses. In our first study, we presented a liquid chromatography method that screens marine shellfish meat for the presence of lipophilic marine toxins. Here, we developed a HPLC-MS method to detect marine toxins at the source: the phytoplankton community.

Scientific abstract

During the last decade, a significant increase in the occurrence of harmful algal blooms (HABs), linked to repetitive cases of shellfish contamination has become a public health concern and therefore, accurate methods to detect marine toxins in different matrices are required. In this study, we developed a method for profiling lipophilic marine microalgal toxins based on ultra-high-performance liquid chromatography coupled to high-resolution Orbitrap mass spectrometry (UHPLC-HR-Orbitrap MS). Extraction of selected toxins (okadaic acid (OA), dinophysistoxin-1 (DTX-1), pectenotoxin-2 (PTX-2), azaspiracid-1 (AZA-1), yessotoxin (YTX) and 13-desmethyl spirolide C (SPX-1)) was optimized using a Plackett-Burman design. Three key algal species, i.e., Prorocentrum lima, Protoceratium reticulatum and Alexandrium ostenfeldii were used to test the extraction efficiency of OA, YTXs and SPXs, respectively. Prorocentrum micans, fortified with certified reference solutions, was used for recovery studies. The quantitative and confirmatory performance of the method was evaluated according to CD 2002/657/EC. Limits of detection and quantification ranged between 0.006 and 0.050 ng mL-1 and 0.018 to 0.227 ng mL-1, respectively. The intra-laboratory reproducibility ranged from 6.8 to 11.7 %, repeatability from 6.41 to 11.5 % and mean corrected recoveries from 81.9 to 119.6 %. In addition, algae cultures were retrospectively screened for analogues and metabolites through a homemade database. Using the ToxID software programme, 18 toxin derivates were detected in the extract of three toxin producing microalgae species. In conclusion, the generic extraction and full-scan HRMS approach offers an excellent quantitative performance and simultaneously allows to profile analogues and metabolites of marine toxins in microalgae.

Full reference (link)

Orellana, G.M., Van Meuleboek, L., Van Vooren, S., De Rijcke, M., Vandegehuchte, M., Janssen, C.R., Vanhaecke L. 2015. Quantification and profiling of lipophilic marine toxins in microalgae by UHPLC coupled to high-resolution orbitrap mass spectrometry. Analytical and Bioanalytical Chemistry, accepted article.