Incorporation of carbon nanotubes in a silica HPLC column to enhance the chromatographic separation of peptides: Theoretical and practical aspects

Abstract

The retention mechanism of a series of peptides on a single-wall carbon nanotube (SWCNT) stationary phase inside an HPLC column was investigated over a wide range of mobile phase compositions. While the similar size C18 column exhibited an efficiency of 11.5 μm, the SWCNT column increased the efficiency, i.e. 7.10 μm at a flow rate of 0.8 mL/min, and significantly affected the separation quality of the peptides. The values of enthalpy (ΔH) and entropy (ΔS(*)) of transfer of the peptides from the mobile to the SWCNT stationary phase were determined. The method studied each factor, i.e. ACN fraction x in the ACN/water mixture and column temperature. The changes in retention factor, ΔH and ΔS(*) as a function of the ACN fraction in the mobile phase were examined. These variations are explained using the organization of ACN in clusters in the ACN/water mixture and on the steric and electronic forces implied in the retention process. The information obtained in this work makes this SWCNT stationary phase useful for peptide research and demonstrated the role of ACN to improve the separation quality.

Nanomaterials as tools in chromatographic methods

“…For instance, the separation of peptides has been studied by incorporating SWCNTs in a silica LC column [52]. The efficiency of this column, given by the height equivalent to a theoretical plate (HETP) was 7.10 µm, whereas a similar size C 18 column in the same experimental chromatographic conditions afforded a HETP value of 11.5 µm.…”

Less common applications of monoliths: V. Monolithic scaffolds modified with nanostructures for chromatographic separations and tissue engineering

“…Recently, MWNT bearing hydroxyl groups were assembled layer‐by‐layer onto micrometer‐sized silica beads to form MWNT/silica composites and used as a stationary phase for the separation of a variety of aromatic compounds []. Shortened SWNT derivatized with amine functionalities were covalently attached to the aminopropyl silica in a pre‐packed column using a glutaraldehyde linker []. This CNT stationary phase was used for the separation of polychlorinated biphenyl isomers, terpenes, and peptides.…”

“…Conditions: columns, 50 mm × 4.6 mm id, 3.5 μm particle size; mobile phase, 5% acetonitrile/95% water; flow rate, 0.8 mL/min; temperature, 55°C. Reproduced with permission from Andre et al [].…”

An HPLC chromatographic framework to analyze the β-cyclodextrin/solute complexation mechanism using a carbon nanotube stationary phase

“…Speltini et al [7] gave an exhaustive overview of the most significative results so far attained in the application of carbon nanotubes, fullerenes and nanodiamonds as chromatographic separation media. In the last few years, our laboratory developed novel HPLC stationary phases based on nanomaterials [8,9]. The retention mechanism of small molecules on such support is not yet fully explained due to the complexity of the different interactions.…”