Direct introduction of aqueous eluents for on–line coupled liquid chromatography–capillary gas chromatography

The on‐line introduction of relatively large volumes of reversed‐phase (aqueous) eluents into a capillary GC column without severe distortion of components eluting at temperatures close to the solvent boiling point is described. The technique, which utilizes an uncoated inlet (retention gap), is based on complete evaporation of the solvent prior to reaching the stationary phase and introduction of components with a dispersion equivalent to that given by a micro‐LC system. Studies of the evaporation within the retention gap, accomplished by introduction of a nonvolatile dye and visual examination of the resulting band patterns, indicated minimum retention gap lengths necessary to prevent liquid solvent from reaching the capillary GC column when aqueous eluents are used. The determination of N‐Serve' (2‐chloro‐6‐[trichloro methyl]pyridine) in corn extract is described.