HIGH-TEMPERATURE VAPORIZING CHAMBERS FOR LARGE-VOLUME GC INJECTIONS AND ONLINE LC-GC

The suitability of some chambers for sample evaporation at high input flow rates (>100 mu l/min) was studied by visual experiments, The cham bers were at temperatures far above the solvent boiling point in order to achieve the heat transfer required, Shooting liquid owing to viole nt evaporation, flooding of the chamber as a result of cooling, and ex cessively high vapor pressure causing backflow into the gas supply sys tem were found to be the limiting factors, Fused silica capillaries in to which a piece of wire or polyimide-free fused silica capillary had been inserted were found to be suitable for the vaporization of ''easy '' solvents, such as alkanes (up to some 1.7 ml/min), bur packed beds were required to achieve favorable evaporation of dichloromethane or m ethanol/water (up to some 800 and 300 mu l/min, respectively).