Characterization of a solventless injection interface for supercritical fluid chromatography

Abstract

Packed column supercritical fluid chromatography (SFC) is capable of highly efficient separations of drug-like molecules with les solvent consumption than HPLC. However, solute peaks in SFC are susceptible to broadening and distortion due to mismatch between the elution strength and viscosity of the injection solvent and the SFC mobile phase. The magnitude of solvent-induced band broadening increases as the elution strength and viscosity of the sample and mobile phase become more dissimilar and varies with the type of stationary phase used and the nature of the solute injected. A number of researchers have coupled supercritical fluid extraction with supercritical fluid chromatography in an attempt to remove solvent from injected samples, and thereby reduce peak broadening and distortion during SFC chromatography. While solventless injection is effective in overcoming solvent-induced band broadening in SFC, there have been few reports dealing with the optimization of the solvent removal process of this technique. In this work, we describe the influence of temperature, purge time, purging gas flow rate, stationary phase used in the sample precolumn, and injection solvent composition on solvent elimination and solute recovery.