ИСТИНА

An overview of current trends in the development of ion-exchangers for ion chromatography (IC) will be presented with focus on column efficiency, separation selectivity and expanded areas of practical application. It considers in which direction future stationary phase development might proceed. The significant improvement in IC column efficiency was noted in the last decade with appearance of new IC equipment allowing operation at elevated pressures up to 5000 psi. This resulted in significant progress in production of microparticulated ion-exchangers with particle size of 2-4 micron. Correspondingly separation efficiency exceeded values 120,000 theoretical plates per meter. In terms of new selectivity a more significant overlapping between IC, mixed-mode HPLC and HILIC was noted in the recent years. A significant number of new stationary phases combining various types of interactions have been reported for these chromatographic modes. This caused more attention to investigation of properties of ion-exchangers for the better understanding of separation mechanism and impacts of various types of sorbate-sorbent interactions in separation selectivity observed in these LC modes. The key to the improvement of ion-exchange selectivity is connected with application of new advanced materials and modification of surface chemistry. Comprehensive IC has a proven track record in the determination of inorganic and organic anions and cations, so more recent applications of IC are related to the separation and determination of bio-molecules such as amino acids, carbohydrates, nucleotides, proteins and peptides and pharmaceuticals. 1) P.N. Nesterenko, Expanding the applications of ion chromatography, LC-GC e-books. Applications of ion chromatography, Advanstar, 2015. 2) P.R. Haddad, P.N. Nesterenko, W. Buchberger, Recent developments and emerging directions in ion chromatography, J. Chromatogr. A, 1184 (2008) 456. 3) E.P. Nesterenko, P.N. Nesterenko, D. Connoly, et al., Nano-Particle Modified Stationary Phases for High-Performance Liquid Chromatography, Analyst 138 (2013) 4229.