Dynamic pre-concentration of light hydrocarbons at room temperature

A prototype of a dynamic pre-concentration system for light hydrocarbons is designed, established and evaluated. It provides a substitute of cryogenic traps for the focus of light hydrocarbons. The manifold techniques of suitable volume sampling, selective solid-adsorption at ambient temperature, timely valve-switching and back-flushing, quick and complete thermodesorption, and analysis on micropacked column am effectively combined. Examples are given for the analysis of ethane, ethylene and acetylene. A 110 fold of enrichment was obtained with only 11 mi, gas sample. The collection/recovery efficiency is more than 98%, and the error of reproducibility is less than 3% RSD. The method is suitable for on-line field monitoring of micro-gas chromatography for trace analysis of gas samples.