Quality test of a mechanical switching valve for two‐dimensional open tubular gas chromatography

Abstract

Abstract A commercially available mechanical micro switching valve has been tested for inertness. The test mixtures used were a modified Grob test and a solution consisting of eight typical aroma compounds, both at the 2‐ng level. Cryogenic focusing of the sample after chromatography including one passage through the valve revealed that irreversible interaction of some test substances with valve components was rather small. A composite main peak of a chromatogram from a fruit juice aroma exhibiting a “mixed odor” was selectively transferred (heart‐cutting) to a second column and resolved into three peaks. GC‐GC/sniffing assigned a minor peak to a substance formerly hidden under the composite peak. Separate heating of the valve during temperature programming of the column was found to be unnecessary.