Sanchez Juan M, Sacks Richard D
Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
J Sep Sci. 2007 May;30(7):1052-60. doi: 10.1002/jssc.200600367.
The performance characteristics of a portable GC instrument requiring no compressed gas supplies and using relatively lightweight transportable components for the analysis of volatile organic components in large-volume air samples are described. To avoid the need for compressed gas tanks, ambient air is used as the carrier gas, and a vacuum pump is used to pull the carrier gas and injected samples through the wall-coated capillary column and a photoionization detector (PID). At-column heating is used eliminating the need for a conventional oven. The fused silica column is wrapped with heater wire and sensor wire so that heating is provided directly at the column. A PID is used since it requires no external gas supplies and has high sensitivity for many compounds of interest in environmental air monitoring. In order to achieve detection limits in the ppb range, an online multibed preconcentrator containing beds of graphitized carbons and carbon molecular sieves is used. After sample collection, the flow direction through the preconcentrator is reversed, and the sample is thermally desorbed directly into the column. Decomposition of sensitive compounds during desorption is greater with air as the carrier gas than with hydrogen.
描述了一种便携式气相色谱仪的性能特点，该仪器无需压缩气体供应，使用相对轻质的可运输部件来分析大量空气样本中的挥发性有机成分。为避免使用压缩气体罐，使用环境空气作为载气，并使用真空泵将载气和注入的样品抽过壁涂毛细管柱和光离子化检测器（PID）。采用柱内加热，无需传统的烘箱。熔融石英柱包裹有加热丝和传感丝，以便直接在柱处提供加热。使用PID是因为它无需外部气体供应，并且对环境空气监测中许多感兴趣的化合物具有高灵敏度。为了实现ppb范围内的检测限，使用了一种在线多床预浓缩器，其包含石墨化碳床和碳分子筛床。样品采集后，通过预浓缩器的流动方向反转，样品直接热解吸进入柱中。与氢气作为载气相比，以空气作为载气时，解吸过程中敏感化合物的分解程度更大。
