Recent development in charged stationary phases for ion exchange chromatography and mixed-mode chromatography.

Ion exchange chromatography (IEC) and mixed-mode chromatography are highly effective for the separation of polar and ionic compounds, including inorganic ions, proteins, peptides, pharmaceuticals, nucleotides, and organic acids, owing to their unique ion exchange or mixed-mode retention mechanisms. As the core component of chromatographic system, the stationary phase directly determines separation selectivity and column efficiency. Therefore, the rational design and development of novel stationary phases remain a focal in modern separation science. In response to the increasing complexity of sample matrices, recent advances have driven the evolution of high‑performance IEC stationary phases that are shifting from a single ion exchange mechanism toward sophisticated multifunctional designs. To better elucidate the critical structure-performance relationships governing the chromatographic behavior, this review provides a comprehensive overview of the evolution of substrates and surface modification strategies (e.g., click chemistry, controlled radical polymerization, and hyperbranched modification) employed in preparing of modern stationary phases over the past decade. Furthermore, this review concludes with a critical discussion of the current challenges and future development trends of chromatographic packing materials.