Instrumentation and strategies for high-speed gas chromatography

Abstract

Short lengths of capillary column operated at unusually high carrier-gas velocities are used to separate relatively simple mixtures on a timescale of 20 s or less. Two inlet systems are described which can generate the narrow injection bands needed for these elution times. A cryofocusing inlet using a vacuum-pump-operated gas flow direction control is used for compounds generally less volatile than n-pentane. A low-friction gas valve inlet combined with porous-layer open-tubular columns is used for volatile compounds of low molecular mass. Strategies for high-speed separations including high-speed backflush, backflush with recycle, vacuum-outlet operation and selective detection are described. These techniques are used to increase the operational flexibility and the amount of information that can be obtained using high-speed gas chromatography.