A systematic review of separation/preconcentration and detection techniques for speciation analysis of arsenic and selenium in water

The speciation of arsenic and selenium in aquatic environments has garnered significant research attention owing to the critical relationship between elemental speciation and both toxicity profiles and bioavailability mechanisms. Over the past two decades, substantial progress has been achieved in developing advanced analytical methodologies for speciation analysis, particularly addressing the challenges posed by arsenic's pronounced toxicity and selenium's dual biological roles. This review systematically examines the separation/preconcentration techniques and detection strategies employed in various aqueous matrices, including riverine systems, lacustrine environments, marine waters, and surface water bodies. A comprehensive evaluation of pretreatment technologies reveals that the matrix complexity and ultra-trace concentration requirements continue to drive methodological innovations, with particular emphasis on solid-phase extraction and chromatographic separation techniques. Analytical advancements are critically assessed through comparative analysis of spectroscopic detection methods (e.g., ICP-MS, AAS, AFS) coupled with separation modalities (e.g., HPLC, IC, MSPE). Critical validation parameters—including detection limits, recovery rates, precision, and enrichment factors—were systematically summarized alongside methodological characteristics such as typical separation media, key devices employed. Studies have shown that although some new pretreatment and detection technologies have emerged, hyphenated techniques still remain the mainstream in speciation analysis research. The review concludes with evidence-based recommendations for method selection guided by sample matrix characteristics and target speciation requirements while highlighting the imperative for continued innovation in achieving species-specific detection at environmentally relevant concentrations.