Two‐dimensional gas chromatography for determination of volatile compounds in ambient air

A two‐dimensional gas chromatograph is described for the analysis of volatile compounds. The chromatographic system consists of two separate chromatographs linked together with an interface containing an intermediate trap. The trap is cooled with nitrogen (−150°C) and a cryogradient is created inside the trap enclosure. The sample is reinjected during controlled (chromatographic) conditions, using thermostated air. The sample components are eluted from the trap as narrow symmetrical peaks; the shape and width of the peaks eluted do not noticeably affect the subsequent chromatography. The enrichment of n‐butane in the trap is quantitative in the range 10−10 – 10−5 g.