CRYOFOCUSING INLET WITH REVERSE FLOW SAMPLE COLLECTION FOR GAS-CHROMATOGRAPHY

An inlet system for high-speed gas chromatography is characterized. Sample is cryofocused in a bare metal capillary tube and released by a fast temperature increase caused by an electric current. The gas flow direction through the capillary tube is reversed after sample collection so that the sample injection onto the capillary column for separation occurs from the downstream end of the metal tube. The system offers narrower initial band widths, elimination of memory effects, and reduced thermal decomposition during reinjection relative to previously described cryofocusing inlet systems. Sample vapor can be collected and cryofocused from any source pressure greater than approximately 20 Torr. A configuration for direct air sampling is described.