低碳烃的常温动态预浓缩方法

Dynamic Pre-concentration of Light Hydrocarbons at Room Temperature

设计了一种常温动态预浓缩方法，用于低沸点气体样品的富集。该方法使用对样品有中等保留强度的吸附剂作为浓缩柱，配以反吹和快速升温技术，实现了对沸点≥－１０３℃样品的常温动态富集和升温快速脱附。整个过程不间断连续完成，从进样至脱附只需几分钟，能以较小的进样量获得较高的浓缩倍数。本文以Ｃ２样品为例进行了实验，在进样量１１ ｍＬ时，得到浓缩倍数≥１００，回收率＞９８％，重复误差≤３％（ＲＳＤ）。该装置适配微型色谱仪，用于痕量分析。本方法同样适用于常规色谱仪。该方法操作简便、可靠性高，可用于环境样品和特殊场合的现场样品的富集和分析，替代了低温冷阱富集的传统方法。

A prototype of a dynamic pre-concentation 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-sdsorption at ambient temperature, timely valve-switching and back-flushing, quick and complete thermodesorption, and analysis on micropacked column are effectively combined. Examples are given for the analysis of ethane, ethylene and acetylene. A 110 fold of enrichment was obtaind with only 11 mL 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 anslysis of gas samples.