热解吸调制,顶空—毛细管气相色谱法测定二元液系的活度系数

本文采用热解吸调制器作毛细管气相色谱直接顶空进样测定二元液体混合物苯－甲苯和丙酮－氯仿的活度系数。热解吸调制器是在毛细管柱前端的一段短的加热段。调制器段外部镀以一薄层导电膜。所体样品连续不断地流经调制器和毛细管柱。

Determination of Activity Coefficients of Binary Liquids by Headspace-Capillary Gas Chromatography With Thermal Desorption Modulation

Activity coefficients of the binary liquid mixtures, benzene-toluene and acetone-chloroform were determined using thermal desorption modulation for direct headspace sampling into capillary gas chromatograph. The thermal desorption modulator is a short, heated section at the head of the capillary column. The modulator section is coated externally with a thin electrically conductive film. A gaseous headspace sample flows continuously through the modulator and the column. The stationary phase within the modulator momentarily retains sample substances from the headspace sample stream. An electrical current pulse has been applied to the electrically conductive, thin film heats the modulator section and the stationary phase within it, releasing any retained substances as a concentration pulse which flows into the following column. The modulator acts like an automatic and highly reproducible small volume injector for a continuously flowing sample stream. Short term relative standard deviations obtained using this technique are approximately 2%. This precision is better than that obtained using other techniques.