# AZA Toxin Profiles by LC-HRMS in Shellfish from Šibenik Bay: AZA-2 Predominant Analog

## TL;DR

This study identifies AZA-2 as the main toxin in shellfish from Šibenik Bay and detects several other azaspiracid analogs, including a potential new one, highlighting the need for expanded monitoring.

## Contribution

The first comprehensive analysis of azaspiracid analogs in Adriatic Sea shellfish using high-resolution mass spectrometry.

## Key findings

- AZA-2 was the predominant analog detected in shellfish samples from Šibenik Bay.
- A potentially new azaspiracid analog (m/z 884.4928) was identified with structural similarity to AZA-19.
- Multiple toxic analogs were detected, suggesting current monitoring programs may be insufficient.

## Abstract

Azaspiracids (AZAs) are marine polyether biotoxins produced by dinoflagellates that accumulate in filter-feeding organisms and pose a threat to human health and seafood safety. This study presents the first comprehensive analysis of azaspiracid analogs in shellfish from the Adriatic Sea with the use of high-resolution mass spectrometry. AZA-2 was quantified in samples collected from Šibenik Bay between January and May 2024, with the highest concentrations observed in early January. In addition to AZA-2, several known analogs (AZA-6, AZA-9, AZA-10, AZA-19, AZA-41, and AZA-43) and a potentially new analog (m/z 884.4928) were also detected. The fragmentation patterns of this new analog indicate a structural similarity to AZA-19 with a possible double bond modification. Potential pitfalls regarding the misinterpretation of spectra derived from molecules containing 13C atoms were recognized and addressed. The presence of multiple analogs, some of which have high toxic potential, suggests that regulatory practice should consider including more than three analogs in the monitoring program.