This Cogent Bidentate C18 "Semi-Preparative", HPLC Column is made with 4um, 100A, Cogent TYPE-C™ Silica, and this silica hydride based stationary phase provides excellent Selectivity, Faster Equilibration and Very Robust Column Lifetimes.Chosen for Purification or "Prep" of Hydrophobic Molecules, Metabolites, and other Analytes with amine groups when a large volume of sample is desired to be collected.A specialized HPLC System is required for columns this size.