Evaluation of new superficially porous particles with carbon core and nanodiamond-polymer shell for proteins...

A new superficially porous material possessing a carbon core and nanodiamond-polymer shell and pore size of 180Å was evaluated for the analysis of large proteins. Because the stationary phase on this new support contains a certain amount of protonated amino groups within the shell structure, the resulting retention mechanism is most probably a mix between reversed phase and anion exchange. However, under the applied conditions (0.1-0.5% TFA in the mobile phase), it seemed that the main retention mechanism for proteins was hydrophobic interaction with the C18 alkylchains on this carbon based material. In this study, we demonstrated that there was no need to increase mobile phase temperature, as the peak capacity was not modified considerably between 30 and 80°C for model proteins. Thus, the risk of thermal on-column degradation or denaturation of large proteins is not relevant. Another important difference compared to silica-based materials is that this carbon-based column requires larger amount of TFA, comprised between 0.2 and 0.5%. Finally, it is important to mention that selectivity between closely related proteins (oxidized, native and reduced forms of Interferon α-2A variants) could be changed mostly through mobile phase temperature.