High temperature gas chromatography on narrow bore capillary columns

The use of high‐temperature‐stable, medium polarity glass capillary columns coated with immobilized PS‐090 (a 20 % diphenyl‐substituted, CH 3 O‐terminated polydimethylsiloxane) has made it possible to analyze routinely, and with good separation efficiency, high molecular weight compounds such as triglycerides and free base porphyrins. Cold on‐column injection was used throughout this work to avoid discrimination against involatile compounds, and disposable (fused silica) retention gaps were used to protect the column against contamination with involatile material. On‐column injection into narrow bore glass columns was achieved by using glass‐to‐silica connections to attach wider bore (0.2 mm i.d.) deactivated fused silica tubing to the columns.