Automated Gas Sampling System for Laboratory Analysis of CH₄ and N₂O†

Analyzing the flux of CH4 and N2O from soil is labor intensive when conventional hand injection techniques are utilized in gas chromatography. An automated gas sampling system was designed and assembled from a prototype developed at the National Soil Tilth Laboratory in Ames, IA. The sampler was evaluated for accuracy and precision when attached to a VarianFootnote1 3700 gas chromatograph configured with flame ionization and electron capture detectors. The automated gas sampling system is easy to operate and provides acceptable results (standards ranging from 1.0–5.0 ppmv CH4 and 0.342–2.0 ppmv N2O had coefficients of variation ranging from 1.7–5.6%) while providing an economical approach for analyzing large numbers of gas samples with minimal labor and equipment cost. 1Mention of commercial products in this paper is solely to provide specific information for the reader. It does not constitute endorsement by the USDA's Agricultural Research Service or the University of Nebraska's Agricultural Research Division over other products that may be suitable. †This paper is a joint contribution of the U.S. Department of Agriculture and University of Nebraska-Lincoln. Published as Journal Series Number 13107.