Modified semi-rotating cryogenic modulator for comprehensive two-dimensional gas chromatography.

A previously constructed semi-rotating cryogenic modulator was modified for comprehensive two-dimensional gas chromatography (GCxGC). The retention time repeatability was improved by replacing the modulator control program unit with a new system. Peak widths obtained with the modified modulator were comparable with those obtained with the previous modulator and other modulator types. The modulator was easy to construct and it can be installed in any commercial GC system. The constructed GCxGC-FID system and data obtained by gas chromatography-mass spectrometry (GC-MS) were used for identification of unknowns in forest aerosol samples.