Automated Gas Chromatographic System for Rapid Analysis of the Atmospheric Trace Gases Methane, Carbon Dioxide, and Nitrous Oxide

To study the fluxes of the radiative active trace gases CH{sub 4}, CO{sub 2}, and N{sub 2}O, a gas sampling and analytical device was developed. It is a useful tool for accurate gas sampling in the field and enables the subsequent fully automated analysis of the gas samples in the laboratory. The computer-controlled analytical system consists of a gas chromatograph equipped with a flame ionization detector (FID), an electron capture detector (ECD), and a pressure-controlled autosampler for 64 sample containers. The system automates sample injection, the analysis of CH{sub 4}, CO{sub 2}, and N{sub 2}O in each sample and the subsequent evacuation of the sample containers. It is equipped with a second alternative sample inlet for manual syringe injection. This inlet is suitable for analyzing small volumes of gas samples (3 mL). The gas sampling system for use in the field consists of evacuated sample bottles (100 mL) with Teflon cocks combined with a small battery-driven field sampler with a pressure sensor. This device enables an on-site control of the vacuum integrity of the sample bottles during sampling and purging of the dead volumes between the sampler induction pipe and the sample container. 11 refs., 4 figs.