Peptide-based chiral derivatizing reagents in nano-scale liquid chromatography: Effect of the oxidation state of cysteine moiety on enantioseparation of ibuprofen

•Peptides were designed to enhance the chiral separation in nano-scale LC.•The tri-oxidized peptides could assist the separation efficiency of C18 column.•Micro-coupling reaction was used to form the derivatives of peptide with analyte.•Computation simulations shown the hydrogen bonds enhance the separation efficiency.•Chiral separation of ibuprofen in tablets and plasma samples proved workable.