AUTOMATED GAS SAMPLING SYSTEM FOR LABORATORY ANALYSIS OF CH\u3csub\u3e4\u3c/sub\u3e AND N\u3csub\u3e2\u3c/sub\u3eO

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 Varian 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