Comprehensive profiling of arsenosugars in algae using UHPLC-HRMS and UHPLC-IMS-Q-TOF

Arsenic is a ubiquitous environmental contaminant, and its toxicological impact is highly dependent on its speciation. In marine edible algae, increasingly consumed for their nutritional value, arsenosugars (As-Sugars) constitute the major arsenic forms. Despite their generally low toxicity, their uncertain long-term effects make accurate identification essential. We developed an analytical workflow combining ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). Both Q-Orbitrap and IMS-Q-TOF systems were employed, operating in positive and negative electrospray ionization (ESI) modes. Using a zwitterionic hydrophilic interaction liquid chromatography (HILIC-Z) column, we achieved effective separation of the target compounds and subsequently performed detailed HRMS and MS/MS analyses. This approach enabled the structural annotation of four key As-Sugars (Gly-Sug, PO₄-Sug, SO₃-Sug, and SO₄-Sug) on the basis of accurate mass measurements and diagnostic fragmentation patterns. Notably, we report for the first time the collision cross-section (CCS) values of these As-Sugars, providing an additional orthogonal parameter that strengthens their confirmation.