Challenges in phycotoxin analysis in marine mammal biological matrices

ARREGUI MARINA; D'AGOSTINO, VALERIA C.; DEGRATI MARIANA; TEBBEN JAN; KROCK BERND

Hiroshima

Congreso; 20th International Conference on Harmful Algae; 2023

Marine mammals (MMs) have great potential as sentinel species to assess the effect of harmful algal blooms (HABs) on the marine ecosystem and public health. Despite this, phycotoxin exposure of MMs remains largely unknown worldwide. Moreover, working with MM tissues and fluids is often challenging due to their complex matrices, the limited sample availability, and the lack of standardized protocol for phycotoxin analysis by liquid chromatography coupled to post-column derivatization and fluorescence detection (HPLC-FLD) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Currently, most of the scarce studies published do not accurately assess the matrix effect (ME) and its role in ion suppression or enhancement in LC-MS/MS. Considering all the above, the present study aimed to select suitable extraction methods to minimize MEs. Different clean-up steps were tested, including hexane washing, protein precipitation, and lipid freezing. Most of the latest work has focused on solid phase extraction (SPE), carrying out different types of SPE (normal, reverse and ion exchange phases) and various cartridge sorbents. So far, results show that the ME is highly dependent on the tissue analyzed. Also, the techniques tried have proven inefficient in significantly reducing the ME and achieving good recoveries for the various phycotoxin classes assessed. In the following months, mixed-mode SPE phases and matrix-matched calibration curves for each type of tissue or fluid will be explored to compensate for ME.