This study investigates the use of both BEH C18 and CSH™ C18 columns for preparative peptide separations. BEH C18 is an organo-silica C18 stationary phase, based on ethylene bridged hybrid (BEH) technology, and is noted for its robustness and pH stability. Charged Surface Hybrid (CSH) C18 is an evolution of BEH C18 as it is modified to contain a low level positive surface charge under acidic conditions. The following data demonstrates that each of these stationary phases is amenable to high mass load peptide separations with both TFA- and HOAc-modified mobile phases. The following results also show that both BEH C18 and CSH C18 can yield narrower target peaks at high mass loads with optimized HOAc mobile phases than those containing 0.1% TFA.