Separation of underivatized small peptides on a porous graphitic carbon column by ion-pair chromatography and evaporative light scattering detection

Separations of small peptides (di-, tri- and tetrapeptides) using ion-pair chromatography and evaporative light scattering detection have been investigated with a porous graphitic carbon stationary phase, Hypercarb(R). Five perfluorinated carboxylic acids (trifluoroacetic (TFA), pentafluoropropanoic (PFPA), heptafluorobutanoic (HFBA), nonafluoropentanoic (NFPA) and tridecafluoroheptanoic (TDFHA) acids) have been evaluated as ion-pairing agents. Influence of the percentage of organic modifier, concentration, and chain length of the ion-pairing agent on the retention factors, k, has been examined. Equilibration times were also studied. Separations of dipeptides or tri- and tetrapeptides are presented using HFBA and NFPA at 20 mM and TDFHA at 2.5 mM.