C60 and C70 HPLC retention reversal study using organic modifiers

Area of Science:

• Analytical Chemistry
• Physical Chemistry

Background:

• Fullerene molecules C60 and C70 present unique challenges for separation science.
• Reversed-phase liquid chromatography (RPLC) is a key technique for analyzing nonpolar compounds.

Purpose of the Study:

• To apply a novel equation for modeling weak polar solute retention to fullerene separation.
• To investigate the influence of organic modifiers on fullerene solvation and elution behavior.

Main Methods:

• Utilized a previously established RPLC model to calculate fullerene solvation energies.
• Examined organic modifier/water mobile phases with varying alcohol chain lengths (methanol to pentanol).
• Analyzed enthalpy-entropy compensation and Gibbs free energy changes in solvent exchange processes.

Main Results:

• Enthalpy-entropy compensation indicated consistent fullerene-stationary phase interactions.
• Calculated solvation energies revealed dependence on organic modifier structure.
• Identified two linear correlations governing solvent exchange energetics.
• Observed a reversal in elution order for C60 and C70 with different organic modifiers.

Conclusions:

• The mobile phase composition significantly impacts selectivity for nonpolar solutes like fullerenes.
• A reversal in elution order for C60 and C70 was confirmed when transitioning from methanol to longer-chain alcohols.
• The study highlights the dominance of mobile phase effects in RPLC selectivity for fullerenes.