Ion-pair chromatography on a porous graphitic carbon stationary phase for the analysis of twenty underivatized protein amino acids

The analysis of twenty underivatized protein amino acids has been achieved on porous graphitic carbon packing material (Hypercarb). Five perfluoroalky l carboxylic acids (trifluoroacetic, heptafluorobutyric, nonafluoropentanoi c, tridecafluoroheptanoic and pentadecafluorooctanoic acid) have been studi ed as ion-pairing reagent. Several parameters (equilibration time, quantiti es adsorbed onto the chromatographic support, concentration and nature of t he ion-pairing reagent, as well as temperature effect) have been studied le ading to the complete separation of these compounds in gradient elution mod e. Evaporative light scattering detector has allowed the detection of these non UV-visible absorbent molecules. The chromatographic methodology develo ped can also be easily coupled with pneumatically assisted electrospray mas s spectrometry. (C) 2000 Elsevier Science B.V. All rights reserved.