High temperature injection and vaporization system for gas chromatography

A gas chromatograph injection system for injecting a measured sample of fluid from a relatively low temperature sample stream into a relatively high temperature vaporization zone through which a carrier gas is flowing comprising a sample block having inlet and outlet ports for the sample stream and a sample flow channel portion therebetween, a tubular closed end syringe member having an aperture in the side thereof immediately adjacent its closed end and a plunger selectively movable toward and away from said closed end to draw fluid samples of a predetermined volume into said syringe through said aperture, packing and guiding means in said sample block to guide the movement of said tubular syringe member on opposite sides of said sample flow channel and prevent leakage, means for partially withdrawing said plunger while said syringe aperture is in the flow channel to collect a measured volume of sample, means to move said syringe and withdrawn plunger together into said vaporization zone, means to force said plunger toward said closed end to expel all of said measured sample into said vaporization zone, means to return said syringe and plunger to its original position, means to heat said vaporization zone to a temperature of at least 450.degree. F., means to fixedly mount said vaporization zone closely adjacent to and in closed communication with said sample block and in axial alignment with the path of movement of said syringe member while insulating it so that when the temperature of all surface areas in the vaporization zone which contact the sample vapor is greater than 450.degree. F. the temperature in the sample block will not exceed about 400.degree. F., said vaporization zone being contained within an enlarged cross-sectioned portion of a heat conductive member, said member being joined to said sample block by a portion of reduced cross-section, and thermal insulation means surrounding said member along a portion thereof which is intermediate said portion of enlarged cross-section and said sample block.