For traditional stationary phases, the main separation mechanism is often single, such as hydrophobic interaction for separating non-polar compounds on reversed-phase packing, and ion-exchange interaction for separating ions on ion-exchange packing.While some complex samples of pharmacology, environment and food are often mixtures of compounds with different properties, such as non-ionic, ionic analytes, which cannot be separated simultaneously on the stationary phase possessing single retention mechanism.Mixed-mode stationary phase can provide the simultaneous separation of mixed species, especially ions and organic compounds.