Polar solvents for the desorption of a liquid chromatographic precolumn coupled on‐line with a capillary gas chromatograph

Coupling column liquid chromatography and gas chromatography on‐line is becoming more important in analytical chemistry. Especially when large amounts of polar solvents can be introduced into the gas chromatograph without any problem, the technique will offer new possibilities. With a DPTMDS retention gap, evaporation rates and flooded zones of some solvents have been determined. Two modes of operation using partially concurrent solvent evaporation conditions are discussed: (1) injecting a sample via a loop of an LC valve followed by introduction into the gas chromatograph with an LC pump; (2) trace enrichment on a precolumn followed by on‐line desorption with n ‐propanol into the gas chromatograph. Preliminary results for a splitter system, inserted between the retention gap and the analytical column which allows a considerable increase of the evaporation rate are also presented.