Improved cryotrap/injector for fast gas chromatography.

摘要

Peltier devices for chilling metal capillary cryotrap tubes in high-speed gas chromatography are designed to replace nitrogen gas chilled by liquid nitrogen as cryotrap chillers. In the design, special emphasis is placed on meeting requirements for rapid injection, low trap temperatures, rapid cool down after injection, analyte retention, size, and power consumption. In 20 min a minimum of -40°C can be reached using single-stage coolers and -67°C using multistage coolers. When traps are ballistically heated by capacitive discharges, maximum trap temperatures are 296°C in single-stage coolers and 484°C in multistage coolers. Thermal recovery after heating requires about 5 s for single-stage coolers and 20 s for multistage coolers. Single-stage devices require ca. 2500 W for operation, while multistage devices only require ca. 100 W. With a multistage cooling arrangement, n-heptane bleeds from the trap, while higher-boiling alkanes are retained. Good quantitation is observed for a series of alkanes n-octane through n-duodecane.