Analysis and characterization of arsenosugars in edible algae

Abstract

This review critically examines the analytical techniques employed for the characterization and speciation of arsenosugars (AsSug) in edible algae, emphasizing their environmental, biological, and regulatory implications. Techniques for processing, extraction, clean-up, separation, and detection are analysed, showcasing their roles in overcoming the complex challenges of analysing arsenosugars in diverse algal matrices. Arsenosugars exhibit significant variability in their functional groups (OH, SO3, SO4, and PO4) and total arsenic (tAs) distribution, influenced by species type and environmental factors. Brown algae show the highest arsenic concentrations (15.3–150 mg/kg), followed by red (2.2–48 mg/kg) and green algae (0.32–28.4 mg/kg), with arsenosugars constituting a substantial fraction of total arsenic across all groups. Processing methods, such as freeze-drying and grinding, are essential for sample homogenization and enhancing extraction efficiency, particularly for cell-wall-bound arsenosugars. Extraction techniques like microwave-assisted and ultrasound-assisted methods are widely used, employing solvents such as MeOH-H2O mixtures and nitric acid to achieve high recoveries. Clean-up processes, including filtration and solid-phase extraction (SPE), ensure the removal of matrix interferences and improve analyte isolation. High-performance liquid chromatography (HPLC) emerges as key separation technique, while inductively coupled plasma mass spectrometry (ICP-MS) remains the preferred detection method for its precision and sensitivity. Despite these advancements, challenges persist due to matrix effects, the lack of certified reference materials (CRM), and limited analytical quality control frameworks. The review underscores the importance of refining these techniques and integrating analytical quality control measures to ensure reproducible results. Public health and regulatory implications are crucial, with certain algal species exceeding recommended inorganic arsenic thresholds. So harmonized standards and improved methodologies are essential to ensure the safe consumption of edible algae globally.