This study exploits the increase in chromatographic retention that accrues from benzoyl derivatization of primary amines as a tool to increase sequence coverage in tryptic peptide mapping. N-hydroxysuccinamide sulfonyl benzoate quantitatively derivatizes primary amines of peptides. Introduction of the hydrophobic benzoyl moiety into peptides increased retention of peptides during reversed-phase chromatography (RPC), particularly in the case of smaller hydrophilic peptides. Short chain (1-6 amino acids) tryptic fragments of model proteins lysozyme, myoglobin, and cytochrome c derivatized with N-hydroxysuccinamide sulfonyl benzoate eluted in the linear acetonitrile gradient. Application of benzoyl derivatization was further extended to achieve complete sequence coverage of a therapeutic protein, recombinant human growth hormone, and in detection of single amino acid polymorphism.