Simultaneous separation of inorganic cations and anions by ion chromatography using strong anionic/zwitterionic mixed micelles as the stationary phase

Mixed micelles obtained by mixing SDS (sodium dodecylsulfate) with Zwittergent-3-14 (N-tetradecyl-N, N-dimethyl- 3-ammonio 1-propanesulfonate) are used as a dynamic stationary phase for the simultaneous ion chromatography of inorganic cations and anions. Analyte cations are separated by the negative charges in the SDS based upon ion-exchange interactions while analyte anions are separated by both the positive and negative charges in Zwittergent-3-14 based upon simultaneous electrostatic attraction/repulsion interactions. The ratio of SDS/Zwittergent-3-14, which constitutes the stationary phase is an important factor in the determination of the retention times and elution orders of the analyte ions. The investigation of the mechanisms involved and the practical applications are discussed in this paper.