Retention-optimization strategy for the high-performance liquid chromatographic ion-pair separation of samples containing basic compounds

New trends in reversed-phase liquid chromatographic separations of therapeutic peptides and proteins: Theory and applications

“…The retention of peptides and proteins can be influenced by adding ion-pairing reagents to the mobile phase [37,[45][46][47]. The ion-pairing reagents interact with the ionized groups of the proteins.…”

Methods for the Peptide Synthesis and Analysis

“…In some cases and in order to achieve sharper peaks, triethylamine is added to suppress those interactions. Presence of ion-pair reagents greatly influences the retention time of peptides [253,254]. In RP-HPLC, isocratic elution, step elution, or gradient elution modes can be utilized to purify peptides and proteins.…”

The Column in Liquid Chromatography

“…Generally, the retention of oppositely charged ionic solutes increases with increasing hydrophobicity (increasing chain length) of the pairing ions when used at identical mobile phase concentrations [370][371][372]. Since the mobile phase concentration of the pairing ion and the organic modifier both affect the surface concentration of the pairing ion, these variables should have the greatest effect on solute ion retention, and should be used for adjusting the mobile phase elution strength [374][375][376]. It has been shown that alkylsulfonate pairing ions of different chain length result in identical solute retention at similar surface concentrations [372].…”