Abstract: There are only two ways to increase the amount of sample that can be purified by preparative reversed phase high performance liquid chromatography (Prep-RP-HPLC) in a single run: (1) The traditional approach is to use a bigger column (greater amount of stationary phase); and (2) Use displacement chromatography which uses the stationary phase more effectively. This invention describes a unique Prep-RP-HPLC technique that uses a C-18/C-8 derivatized silica coated with a hydrophobic quaternary ammonium salt or quaternary phosphonium salt to result in 7 to 12 fold increase in sample loading (of the crude mixture of organic compounds including synthetic crude peptides) in contrast to the conventional Prep-RP-HPLC technique. This increase in sample loading capacity and output is due to the additional surrogate stationary phase characteristic of the C-18/C8 bound quaternary salt. The quaternary surfactant is bound to the C-18/C-8 chains and silanols of the stationary phase.