Sample Vapor Introduction Techniques for Use with Cryofocusing GC Inlet Systems

Two techniques are presented for introducing sample vapor into a capillary metal cold trap tube used as an inlet system for high-speed gas chromatography. In both techniques, the amount of sample vapor introduced is controlled without the use of mechanical valves or sample loops in the sample flow path. If the sample vapor can be introduced continuously at a pressure greater than the required inlet pressure of the separation column, thermal modulation of the metal trap tube can be used to control sample introduction. No mechanical components are required in this system. If the sample vapor pressure is less than the required inlet pressure, a vacuum pump is required to pull the sample into the trap tube. Although a valve is required for this system, the valve is not in the sample flow path. This system can be used for sample introduction from an atmospheric pressure source. Both systems can obtain relative standard deviation values of ±1–3%.