Principal Component Analysis Evaluation of Seven Commercial Ionic Liquid Capillary GC Columns

Introduction

Ionic liquids are organic salts utilized for various industrial applications. Their unique and tunable physicochemical properties are unlike any other solvent. They typically remain liquid over wide temperature ranges, and tend to exhibit low melting points, good thermal stability, negligible vapor pressure, and high viscosity. These properties also make them ideal candidates as stationary phases for gas chromatography (GC). In fact, a quick literature search reveals a great deal of development aimed at preparing columns using ionic liquid stationary phases.

While monocationic ionic liquids can be employed for industrial applications, it was discovered that dicationic and polycationic ionic liquids make suitable GC stationary phases.¹ Currently, there are seven different commercialized capillary GC columns which use ionic liquid stationary phases. Their main advantage is that they offer different separation properties compared to columns prepared with polysiloxane polymer and polyethylene glycol stationary phases. They also exhibit lower column bleed, higher thermal stability, greater resistance to damage from moisture and oxygen, and longer life time when compared to columns of similar polarity.