Fluorinated HPLC Phases — Looking Beyond C18 for Reversed-Phase HPLC
Reversed-phase high performance liquid chromatography (HPLC) is one of the most utilized forms of chromatography (1). The C8 and C18 stationary phases are the most widely used for reversed-phase HPLC. However, analysts occasionally encounter difficult separations for which selectivity, ruggedness, or reproducibility are not obtained easily using traditional C8 and C18 phases. These separations might require the use of novel or selective phases that interact with analytes in a manner different than C8 or C18 phases (2). These types of stationary phases separate compounds based upon selective stationary phase interactions such as steric recognition charge transfer or ?–? interactions (3). One class of selective or novel phases that have been used for a variety of separations are fluorinated phases (4). These fluorinated phases have provided an alternative and complementary separation for many analytes performed on C8 or C18 columns. Fluorinated phases can provide different elution orders, leading to..