The widespread diatom Pseudo-nitzschia can produce domoic acid (DA). DA is a compound with well described neurotoxic effects on vertebrates including humans known as amnesic shellfish poisoning (ASP) syndrome. It has also been suggested to serve as an organic ligand that binds to iron and copper. By binding these trace elements, DA may increase their solubility and bioavailability. In order to serve this function, DA has to be excreted and reabsorbed by the cells. Only few records of dissolved domoic acid (dDA) concentrations in the ocean exist. To accomplish quantification by ultra performance liquid chromatography (UPLC), samples have to be pre-concentrated and desalted using solid-phase extraction, a procedure commonly applied for dissolved organic matter. Our major goals were to quantify dDA in a basin-wide assessment in the East Atlantic Ocean, to determine extraction efficiencies for complexed and uncomplexed dDA, and to assess whether domoic acid is represented by its molecular formula in direct-infusion high resolution mass spectrometry. Our results showed that dDA was extracted almost quantitatively and occurred ubiquitously in the ocean surface but also in deeper (and older) water, indicating surprisingly high stability in seawater. The maximum concentration measured was 173 pmol L⁻¹ and the average molar dDA carbon yield was 7.7 ppm. Both carbon yield and dDA concentration decreased with increasing water depth. Providing quantification of dDA in the water column, we seek to improve our understanding of toxic bloom dynamics and the mechanistic understanding of DA production.

广泛硅藻拟菱形藻可以产生多摩酸（DA）。DA是一种化合物，对脊椎动物（包括人类）的神经毒性作用广为人知，被称为遗忘性贝类中毒（ASP）综合征。还已经建议将其用作与铁和铜结合的有机配体。通过结合这些微量元素，DA可以增加其溶解度和生物利用度。为了发挥这种功能，DA必须被细胞排泄并重新吸收。仅有很少的海洋中溶解的海藻酸（dDA）浓度的记录。为了通过超高效液相色谱（UPLC）进行定量，必须使用固相萃取对样品进行预浓缩和脱盐，该方法通常用于溶解有机物。我们的主要目标是在东大西洋的全流域评估中量化dDA，以确定复合和非复合dDA的萃取效率，并评估直接注入高分辨率质谱法中吗啡酸是否由其分子式表示。我们的结果表明，dDA几乎是定量提取的，并且普遍存在于海洋表面，但也存在于更深（和更旧）的水中，这表明在海水中的稳定性极高。测得的最大浓度为173 pmol L^-1，并且平均dDA摩尔平均碳产率为7.7 ppm。碳产量和dDA浓度均随水深的增加而降低。通过对水柱中的dDA进行定量分析，我们寻求加深对有毒水华动力学和DA生产机理的了解。