Bridging the gap between gas and liquid chromatography

The rapid and complete baseline separation of both volatile (C₅ to C₁₆ alkanes in gasoline or terpenes in plant extracts) and non-volatile (>C₂₀ alkanes) organic compounds was achieved by combining (1) low-density fluid chromatography (LDFC) using carbon dioxide at elevated temperature (>90°C) and low pressure (1500psi) designed to increase the retention of the most volatile compounds and (2) high-vacuum technology (<10^-4Torr) in order to preserve the maximum efficiency of short analytical columns (3.0mm×150mm packed with 1.8μm fully porous HSS-SB-C₁₈ particles) when used in LDFC. The volatile compounds are eluted first under isobaric conditions (1500psi) in less than a minute followed by a linear gradient of the column back pressure (from 1500 to 3500psi in 5min) for the elution of the non-volatile compounds up to C₄₀. The experimental results demonstrate that LDFC performed with short 3.0mm i.d. columns packed with sub-2μm particles and placed under adiabatic conditions enables the analysts to deliver a single, fast, and high-resolution separation of both volatile and non-volatile compounds.