Characterization of a highly stable mixed‐mode reversed‐phase/weak anion‐exchange stationary phase based on hybrid organic/inorganic particles
Thomas H. Walter, Bonnie A. Alden, Jessica Field, Nicole L. Lawrence, Donna L. Osterman, Amit Patel, Maureen A. DeLoffi
Abstract
Abstract We have characterized Atlantis ethylene‐bridged hybrid C 18 anion‐exchange, a mixed‐mode reversed‐phase/weak anion‐exchange stationary phase designed to give greater retention for anions (e.g., ionized acids) compared to conventional reversed‐phase materials. The retention and selectivity of this stationary phase were compared to that of three benchmark materials, using a mixture of six polar compounds that includes an acid, two bases, and three neutrals. The compatibility of the ethylene‐bridged hybrid C 18 anion‐exchange material with 100% aqueous mobile phases was also evaluated. We investigated the batch‐to‐batch reproducibility of the ethylene‐bridged hybrid C 18 anion‐exchange stationary phase for 27 batches across three different particle sizes (1.7, 2.5, and 5 μm) and found it to be comparable to that of one of the most reproducible C 18 stationary phases. We also characterized the acid and base stability of the ethylene‐bridged hybrid C 18 anion‐exchange stationary phase and the results show it to be usable over a wide pH range, from 2 to 10. The extended upper pH limit relative to silica‐based reversed‐phase/weak anion‐exchange materials is enabled by the use of ethylene‐bridged hybrid organic/inorganic particles. The improved base stability allows Atlantis ethylene‐bridged hybrid C 18 anion‐exchange to be used with a wider range of mobile phase pH values, opening up a greater range of selectivity options.